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1
Krapp, Andreas, Ulrich Schiefele, Klaus Peter Wild, and Adolf Winteler. "Der „Fragebogen zum Studieninteresse" (FSI)." Universität Potsdam, 1993. http://opus.kobv.de/ubp/volltexte/2009/3360/.
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Die vorliegende Arbeit berichtet über die Entwicklung des „Fragebogen zum Studieninteresse" (FSI) und seine testtheoretische Überprüfung. An der Untersuchung nahmen 298 Studenten verschiedener Studiengänge teil. Ausgehend von einer 27 Items umfassenden Version verblieben aufgrund von Faktorenanalyse und Rasch- Skalierung 18 Items, die eine eindimensionale Skala bilden. Die interne Konsistenz (Alpha) des revidierten FSI beträgt .90, die Test-Retest-Reliabilität .67 (Zeitspanne: 2 Jahre). Zur Prüfung der Validität des revidierten FSI wurde eine Reihe weiterer Variablen erhoben (z.B. intrinsische motivationale Orientierung, Tätigkeitszentrierung, Extraversion, Verwendung von Lernstrategien, Studienleistung). Die Ergebnisse zeigen, daß der FSI in ausreichendem Maße konvergente, diskriminante und kriteriumsbezogene Validität besitzt.This article reports the development of the "Study Interest Questionnaire" (SIQ). A total of 298 university students took part in a study that was designed to test the reliability and validity of the SIQ. The original version of the SIQ included 27 items. On the basis of factor and Rasch analyses we obtained a unidimensional version consisting of 18 items. The revised version of the SIQ showed considerable internal consistency (Alpha = .90) and test-retest reliability (.67; time lag: 2 years). In order to test the convergent, discriminant, concurrent, and predictive validity of the SIQ, a number of additional variables were assessed (e.g., intrinsic motivational orientation, extraversión, use of learning strategies, achievement). The results confirm that the SIQ is a sufficiently valid instrument.
2
Bergmann-Paulsen, Jonas. "FSI-analysis of a Francis turbine." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for energi- og prosessteknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-19081.
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Sediment erosion in Francis turbines is a big problem in hydropower plants in and around the Himalayas. The sediment composition in the rivers contains high levels of the hard mineral quarts. When the sediments enter the turbine they cause erosive damage to exposed parts such as covers, guide vanes and runner. The sediment concentration is at its highest during the monsoon period. During this period some turbines are stopped when the sediment consentration reaches certain levels to reduce the damage. Jhimruk power plant in the mid-western part of Nepal is a good example of how the sediment erosion affects the operation of a power plant. During the monsoon period the turbines can be eroded to an almost unrepairable state. The turbines have to go through substantial annually maintenance. A result of this is reduced power output and high maintenance costs. It is therefore of interest to design a new Francis turbine that can better withstand the sediment erosion. A cooperation project between Kathmandu University and The Norwegian University of Science and Technology was started as a part of the RenewableNepal project which aims to develop and start manufacturing of erosion resistant Francis turbines.A parameter study of different blade designs have been performed to find a more erosion resistant design. In this thesis FSI analyses have been performed on three different designs to verify their structural integrity. The designs transfers the hydraulic energy from the water to the blade in different sections. The results showed a stress distribution which coincided with the energy transfer along the blade. The reference design was analyzed with two different blade thickness. For all the designs the stress was relatively low compared to the criteria for hydraulic turbines.
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De, La Peña-Cortes Jesus Ernesto. "Development of fluid-solid interaction (FSI)." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/development-of-fluidsolid-interaction-fsi(b22b29e2-0349-44a9-ab18-eeb0717d18c8).html.
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This work extends a previously developed finite-volume overset-grid fluid flow solver to enable the characterisation of rigid-body-fluid interaction problems. To this end, several essential components have been developed and blended together. The inherent time-dependent nature of fluid-solid interaction problems is captured through the laminar transient incompressible Navier-Stokes equations for the fluid, and the Euler-Newton equations for rigid-body motion. First and second order accurate time discretisation schemes have been implemented for the former, whereas second and third order accurate time discretisation schemes have been made available for the latter. Without doubt the main advantage the overset-grid method offers regarding moving entities is the avoidance of the time consuming grid regeneration step, and the resulting grid distortion that can often cause numerical stability problems in the solution of the flow equations. Instead, body movement is achieved by the relative motion of a body fitted grid over a suitable background mesh. In this case, the governing equations of fluid flow are formulated using a Lagrangian, Eulerian, or hybrid flow description via the Arbitrary Lagrangian-Eulerian method. This entails the need to guarantee that mesh motion shall not disturb the flow field. With this in mind, the space conservation law has been hard-coded. The compliance of the space conservation law has the added benefit of preventing spurious mass sources from appearing due to mesh deformation. In this work, two-way fluid-solid interaction problems are solved via a partitioned approach. Coupling is achieved by implementing a Picard iteration algorithm. This allows for flexible degree of coupling specificationby the user. Furthermore, if strong coupling is desired, three variants of interface under-relaxation can be chosen to mitigate stability issues and to accelerate convergence. These include fixed, or two variants of Aitkenâs adaptive under-relaxation factors. The software also allows to solve for one-way fluid-solid interaction problems in which the motion of the solid is prescribed. Verification of the core individual components of the software is carried out through the powerful method of manufactured solutions (MMS). This purely mathematically based exercise provides a picture of the order of accuracy of the implementation, and serves as a filter for coding errors which can be virtually impossible to detect by other means. Three instances of one-way fluid-solid interaction cases are compared with simulation results either from the literature, or from the OpenFOAM package. These include: flow within a piston cylinder assembly, flow induced by two oscillating cylinders, and flow induced by two rectangular plates exhibiting general planar motion. Three cases pertaining to the class of two-way fluid-interaction problems are presented. The flow generated by the free fall of a cylinder under the action of gravity is computed with the aid of an intermediate âmotion trackingâ grid. The solution is compared with the one obtained using a vorticity based particle solver for validation purposes. Transverse vortex induced vibrations (VIV) of a circular cylinder immersed in a fluid, and subject to a stream are compared with experimental data. Finally, the fluttering motion of a rectangular plate under different scenarios is analysed.
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Fortelný, Zdeněk. "Optimalizace energetického zásobování FSI - areál Technická 2." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-227960.
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The subject of this diploma thesis is the optimalization of energetic supply of FME- Technická 2, Brno. The supply optimalization is thematically connected to Ing. Jan Kučera´s diploma thesis. The project is divided into several parts. One part is focused on general clarification of the term cogeneration and possible pertinent technologies. The contemporary state and energetic needs of area are analyzed in the second practical part of the thesis. Remaining chapters are focused on comparison and economical analysis of the proposed modules. The conclusion is devoted to the overall effect of selected modules on energetic consumption in the object.
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Andersson, Christoffer, and Daniel Ahl. "Fluid Structure Interaction: Evaluation of two coupling techniques." Thesis, Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-16050.
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This thesis concerns one of the upcoming and well discussed subjects withincalculations these days, namely how to perform an analysis of the interactionbetween fluid and structure, called FSI (Fluid Structure Interaction). In the report,evaluations of two different methods of simulating FSI are done. These are knownas Practical FSI (P-FSI) and Direct Coupled FSI (DC-FSI). The methods aredeveloped by Acusim in cooperation with Simulia and the softwares used areAbaqus and AcuSolve.The first part of the thesis is dedicated to explain the general theory and thegoverning equations for FSI. After the general explanation a more delimitatedexplanation regarding P-FSI and DC-FSI are given. After this we show how tosetup and perform the couplings regarding which parameters that need to bedefined and how to perform the analyses using Abaqus and AcuSolve.The last section of the thesis covers the evaluation process. We started withevaluating the methods against a benchmark problem where we compared thecalculation time and accuracy regarding displacements and frequencies. The nextthing we evaluated was how different numbers of modes used in the P-FSIcoupling affects the result. The last thing we evaluated was the robustness of themethods using different mass densities of the structure and different time-stepsizes.The result of the evaluation regarding the criteria: accuracy, calculation time androbustness showed that the P-FSI method is the most efficient method comparedto DC-FSI regarding FSI problems when the structural response is linear.
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Snashall, Nicole Jane. "Alglat for modules over FSI rings and reflexivity." Thesis, University of Leicester, 1990. http://hdl.handle.net/2381/34570.
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For a bimodule RMDelta where R and Delta are rings with unity, alglat RMDelta is the ring of all Delta-endomorphisms of M leaving invariant every R-submodule of M. The bimodule is said to be reflexive if the elements of alglat RMDelta are precisely the left scalar multiplications by elements of R. For most of the thesis Delta = R, a commutative ring with unity. However, in the early work, some results on the general structure of alglat are obtained, and in particular, Theorem 1.9 shows that it is an inverse limit. The next section of the thesis is concerned with reflexivity, and considers rings R for which all non-torsion or all finitely generated R-modules are reflexive. Theorem 3.4 gives eight equivalent conditions on an h-local domain R to the assertion that every finitely generated R-module is reflexive, that is R is scalar-reflexive. A local version of this property is introduced, and it is shown in Theorem 2.17 that a locally scalar-reflexive ring is scalar-reflexive. The remainder of this thesis considers alglat for all modules over an FSI ring. The local FSI rings are precisely the almost maximal valuation rings, and this is the first case to be settled. More details are then given of the structure of FSI rings and related rings. A completion is introduced in 6.4 to enable alglat to be determined for certain torsion modules over an indecomposable FSI ring. Theorem 7.3, in summarising the work of the last two chapters of the thesis, gives a complete characterisation of alglat for all modules over an FSI ring.
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Chitrakar, Sailesh. "FSI analysis of Francis turbines exposed to sediment erosion." Thesis, KTH, Kraft- och värmeteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-133298.
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Sediment erosion is one of the key challenges in hydraulic turbines from a design and maintenanceperspective in Himalayas and Andes. Past research works have shown that the optimization of theFrancis turbine runner blade shapes can decrease erosion by a signicant amount. This study conductedas a Master's Thesis has taken the proposed designs from past works and conducted a CFDanalysis on a single passage of a Francis runner blade to choose an optimized design in terms of erosionand eciency. Structural analyses have been performed on the selected design through one-way andtwo-way FSI to compare the structural integrity of the designs.Two types of cases have been considered in this thesis work to dene the boundary condition of thestructural model. In the rst case, a runner blade is considered to have no in uence of the joint andother stier components. In the second case, a sector of the whole runner has been modeled withnecessary boundary conditions. Both one-way and two-way FSI have been performed on the casesfor the designs. Mesh independent studies have been performed for the designs, but only for the rstcase, whereas in the second case, a ne mesh has been used to make the analysis appropriate.The loads have been imported into the structural domain from the uid on the interfaces for one-wayFSI. In the case of two-way FSI, the Multi-Field Solver (MFX) supported by ANSYS has been usedto solve the coupled eld analysis. A fully coupled FSI in ANSYS works by writing an input le inthe structural solver containing the information about the interfaces in the structural domain, whichis imported in the uid solver. The interaction between the two domains is dened in ANSYS-CFX,including the mesh deformation and solver setups. The results have been post-processed in CFX-Post,where the results from both the elds are included. It has been found that the structural integrity ofthe optimized design is better than the reference design in terms of the maximum stress induced inthe runner. The two-way FSI analysis has been found as an inevitable part of the numerical analysis.However, with the advancement of the computational capability in the future, there could be a greatscope in the research eld to carry out a fully-coupled transient simulation for the whole runner toget a more accurate solution.
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CARO, DIAZ FREDDY SANTIAGO. "ANALYSIS OF FLUID STRUCTURE-INTERACTION (FSI) PROBLEMS IN ANSYS." Thesis, Faculty of Engineering and Information Technologies. School of Aerospace, Mechanical & Mechatronic Engineering, 2015. https://hdl.handle.net/2123/30023.
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The Fluid-Structure Interaction problems occur in many natural phenomena and man-made engineering systems, this fact has promoted the research in this area. The research in this field of study is implementing two different methodologies. The first one is the use of commercial programs that have developed FSI capabilities such as Ansys or ADINA. The second methodology is the development of computational codes to solve specific problems of FSI analysis. This Project in particular focuses in the evaluation of Ansys-Fluent to perform FSI simulations. Two aeroelastic cases were simulated in Ansys, they were: the delta wing, and the Onera M6 wing. The delta wing simulation is subsonic and its structure is a simple flat plate made out of aluminum. The Onera M6 wing simulation is transonic and its structure has multiple components that are made out of an orthotropic material. The FSI simulations of the delta wing were validated through comparison with experimental data reported in literature. A turbulence analysis and a mesh independence analysis were carried out as well. The validation showed a limited capability to replicate the results that were obtained in the experiment. The FSI simulations of the Onera M6 wing were validated through comparison with a simulation that was carried out in Patran-Nastran. In addition, a computational fluid dynamics (CFD) simulation in steady state was performed in Ansys in order to establish the bases of the configuration that was implemented in the FSI simulations in Ansys. The validation showed that Ansys-Fluent is able to reproduce the results obtained in Patran-Nastran.
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Klapal, Tomáš. "Matematický model univerzální stanice v laboratoři VUT FSI OFI." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-228177.
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This diploma thesis deals with project and experimental verification of mathematical model of experimental circuit for measuring turbine in laboratory of Kaplan Department of Fluids Engineering FME BUT in Brno. Pressure and flow characteristics were modeled based on data measured on general-purpose experimental circuit. Possibilities of the circuit control, mainly by by-pass, were also taken into account. Characteristic curves should serve for preliminery design of the test circuit set up for the turbine model measurements.
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De, Villiers Anna Magdalena. "A patient-specific FSI model for vascular access in haemodialysis." Doctoral thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/24441.
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This research forms part of an interdisciplinary project that aims to improve the understanding of haemodynamics and vascular mechanics in arteriovenous shunting. To achieve the high flow rates that enable patients with renal disease to receive haemodialysis, a fistula is created between an artery and a vein. The patency rate of fistulas, especially those located in the upper arm, is low. The approach adopted here makes use of new magnetic resonance image (MRI) technology and computational modelling of blood flow, with a view to improving therapeutic strategies of disease requiring vascular interventions. This thesis presents the construction and development of a 3D finite element model of the fluid-structure interaction in a brachial–cephalic patient–specific fistula. An overview of the mathematical models that describe the vessel wall and fluid behaviour as well their interaction with each other is given. An Arbitrary Lagrangian- Eulerian (ALE) framework is used together with a transversely isotropic hyperelastic constitutive model for the vessel walls, while blood flow is modelled as a Newtonian fluid. A three-element Windkessel model is used to allow the fluid to move through the outlets of the computational domain without causing non–physical reflections. Flow data acquired from MRI is used to prescribe the flow at the inlet. The parameters of the Windkessel-model at the two outlets are calibrated to resemble the flow acquired from the 2D MRI. The model is validated against the flow patterns acquired from the 4D MRI. The flow patterns of the blood, and stress present in the vessel are investigated. Of special significance are the flow and wall shear stress at the anastomosis. An area of very high velocity in the anastomosis is followed by an area of recirculation and low velocity. The propagation of pressure waves and their reflection at the anastomosis are studied. Areas that are subjected to low wall shear stress, high oscillatory wall shear stress or flow circulation are identified as areas where intimal hyperplasia may develop. The flow results from the simulation show good qualitative agreement with the MRI data.
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Cox, Jonathan T. J. "ATLAS FSI retroflectors and inner detector B-field calibration study." Thesis, University of Oxford, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.558441.
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The start of data taking at the Large Hadron Collider should make a new frontier in particle physics accessible for the first time. The ATLAS experiment has been designed to take advantage of this opportunity to complete the standard model, whilst having the maximum possible sensitivity to the new physics. The alignment accuracy of the Silicon tracking detectors will be vital if ATLAS is to contribute optimally to precision and discovery physics. In response to this difficult challenge, a novel laser alignment system that can precisely measure 842 lengths between grid nodes attached to the detector support structure has been developed. Each of the lengths is monitored remotely via interferometry and this thesis reports on the punched corner cube retroreflectors that form the end nodes of each interferometer grid line. The development of a process to successfully manufacture, and to ensure the finished quality of, approximately 700 retroreflectors is reported. Optical surface profileometry of retroreflector surfaces has been used to investigate the flatness and angles between reflecting faces. A detailed optical simulation has modelled the observed features in the diffraction patterns from a variety of real retroreflectors. Additionally a method to calibrate B-field scale factors, for the solenoid tracking volume, based on Z-boson decay products is reported. The algorithm is able to retrieve applied changes to the magnetic field in 7]-binned regions of the tracking volume. The stability of the calibration algorithm is tested for 50'000 Z ~ f.1+ 11- decays.
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Danzinger, Victor Andreas [Verfasser]. "Charakteristika und Klassifikation der funktionellen Schulterinstabilität (FSI) / Victor Andreas Danzinger." Berlin : Medizinische Fakultät Charité - Universitätsmedizin Berlin, 2020. http://d-nb.info/121807695X/34.
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Pazdera, Igor. "Úprava parkovacích míst v areálu VUT FSI, Technická 2, Brno." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-228427.
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Diploma thesis is concerned with problems of parking places in VUT FSI area, Technická 2, Brno. In introduction there are explained methods of parking, sorting and orientation proportions of vehicles. Then there are explained basic requirements for parking areas according to valid norms and rules. In this task there is analyzed original and actual status of parking. Before separating suggestions is finished calculation of required number of parking places. Solution of whole problems around parking places is in three projects. Results are compared in conclusion.
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Krittian, Sebastian Benedikt Sylvester. "Modellierung der kardialen Strömung-Struktur-Wechselwirkung : Implicit coupling for KaHMo FSI /." Karlsruhe : Lehrstuhl und Institut für Strömungslehre, Universität Karlsruhe (TH), 2009. http://opac.nebis.ch/cgi-bin/showAbstract.pl?sys=000252248.
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Buchschmid, Martin [Verfasser]. "ITM-Based FSI-Models for Rooms with Absorptive Boundaries / Martin Buchschmid." Aachen : Shaker, 2012. http://d-nb.info/106904797X/34.
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Kara, Mustafa Can. "Fluid-structure interaction (FSI) of flow past elastically supported rigid structures." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/51931.
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Fluid-structure interaction (FSI) is an important physical phenomenon in many applications and across various disciplines including aerospace, civil and bio-engineering. In civil engineering, applications include the design of wind turbines, pipelines, suspension bridges and offshore platforms. Ocean structures such as drilling risers, mooring lines, cables, undersea piping and tension-leg platforms can be subject to strong ocean currents, and such structures may suffer from Vortex-Induced Vibrations (VIV's), where vortex shedding of the flow interacts with the structural properties, leading to large amplitude vibrations in both in-line and cross-flow directions. Over the past years, many experimental and numerical studies have been conducted to comprehend the underlying physical mechanisms. However, to date there is still limited understanding of the effect of oscillatory interactions between fluid flow and structural behavior though such interactions can cause large deformations. This research proposes a mathematical framework to accurately predict FSI for elastically supported rigid structures. The numerical method developed solves the Navier-Stokes (NS) equations for the fluid and the Equation of Motion (EOM) for the structure. The proposed method employs Finite Differences (FD) on Cartesian grids together with an improved, efficient and oscillation-free Immersed Boundary Method (IBM), the accuracy of which is verified for several test cases of increasing complexity. A variety of two and three dimensional FSI simulations are performed to demonstrate the accuracy and applicability of the method. In particular, forced and a free vibration of a rigid cylinder including Vortex-Induced Vibration (VIV) of an elastically supported cylinder are presented and compared with reference simulations and experiments. Then, the interference between two cylinders in tandem arrangement at two different spacing is investigated. In terms of VIV, three different scenarios were studied for each cylinder arrangement to compare resonance regime to a single cylinder. Finally, the IBM is implemented into a three-dimensional Large-Eddy Simulation (LES) method and two high Reynolds number (Re) flows are studied for a stationary and transversely oscillating cylinder. The robustness, accuracy and applicability of the method for high Re number flow is demonstrated by comparing the turbulence statistics of the two cases and discussing differences in the mean and instantaneous flows.
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Encarnação, Paulo Victor Hauck da. "FSI: uma infraestrutura de apoio ao projeto FrameNet utilizando web semântica." Universidade Federal de Juiz de Fora (UFJF), 2014. https://repositorio.ufjf.br/jspui/handle/ufjf/4830.
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O projeto FrameNet é um projeto desenvolvido pelo International Computer Science Institute (ICSI) em Berkeley, com o objetivo de documentar frames da língua inglesa baseando-se no conceito de frames semânticos da Inteligência Computacional. Sendo também estendido para outras línguas, como, por exemplo, o Projeto FrameNet-Br, de senvolvido na Universidade Federal de Juiz de Fora, que tem como foco a documentação dos frames linguísticos em português do Brasil. O recurso lexical construído pelo Frame Net pode ser utilizado em diversas aplicações de Processamento de Linguagem Natural, como traduções, sumarização, dentre outras. A utilização de tecnologias de web semân tica, como ontologias e dados ligados podem trazer diversos benefícios que colaboram com o compartilhamento das informações, principalmente considerando a possibilidade de uso de mecanismos de inferência para validação dos dados e obtenção de novas informações. Além disso, o uso de anotações semânticas em serviços Web também é considerado uma tecnologia promissora para facilitar a integração de recursos computacionais na web, ser vindo como mecanismo para facilitar a interação entre ferramentas de software. Estas anotações permitem que ferramentas possam compreender a estrutura dos serviços e como executá-los de maneira automática Desta forma, considerando as vantagens apresentadas por estas tecnologias, é possível associa-las de maneira a criar uma infraestrutura que permita a utilização de recursos lexicais em conjunto com recursos da web semântica para facilitar a compreensão e busca por informações em um dado domínio. Neste trabalho foi especificada uma infraestrutura baseada em serviços, que busca aliar as tecnologias da web semântica aos dados da base do projeto FrameNet, a partir da hipótese de que a aplicação de tecnologias como ontologias, dados ligados, e anotações em serviços Web podem contribuir com a construção e reuso de recursos lexicais baseados na semântica de frames, sendo estas contribuições tanto voltadas para a confiabilidade dos dados, quanto para o enriquecimento das informações mantidas pela base lexical.
The FrameNet project is developed by the International Computer Sciences Institute (ICSI) in Berkeley, with the goal of documenting frames of the English language based on the concept of semantic frames of Computational Inteligence. The FrameNet has been well translated for other languages, such as the FrameNet-BR Project, developed at the Universidade Federal de Juiz de Fora (UFJF), which focus on the documentation of lin guistic frames in Portuguese from Brazil. The lexical resource built by FrameNet can be used in many applications of natural language processing, such translations, summariza tion, among others. The use of semantic web technologies, such ontologies and linked data can bring many benefits that contribute to the sharing of information, specially con sidering the possibility of the use of inference mechanisms to validate data and retrieve new information. The use of semantic annotations for Web services is also considered a promising technology to facilitate the integration of computational resource on the web, serving as mechanism to facilitate interaction between software tools. These annotations allow tools understand the structure of services and how to execute them automatically. Thus, considering the advantages presented by these technologies, it is possible to asso ciate them in order to create an infrastructure that enables the use of lexical resources in conjunction with semantic web resources to facilitate understanding and search for information in a given domain. In this work was specified a service-based infrastructure that seeks to combine the technologies of semantic web to the database of the FrameNet project, considering the hypothesis that the application of technologies such as ontologies, linked data, and annotations in Web services can contribute to the construction and reuse of lexical resources based on semantic frames, and these contributions are both related to the reliability of data, and for the enrichment of the his information kept by lexical base.
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Rojo, Berroeta Maximiliano Adolfo Simón. "Sensibilidad de Resultados de Simulaciones no FSI de Modelos de Aneurismas Cerebrales." Tesis, Universidad de Chile, 2008. http://repositorio.uchile.cl/handle/2250/104916.
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El presente trabajo de título forma parte del proyecto FONDECYT Flow Dynamics
and Arterial Wall Interaction in Realistic Cerebral Aneurysm Models. El objetivo general
del trabajo es mejorar la descripción de la mecánica de sólidos en aneurismas cerebrales
hecho hasta la fecha en el proyecto, a través de un análisis de sensibilidad de los resultados
de simulaciones numéricas sin interacción fluido-estructura (No FSI), modificando
parámetros mecánicos y geométricos. El desafío que representa en el área de la
Biomecánica el análisis de esta enfermedad motiva a aportar al entendimiento de su
evolución y con ello, a la posible prevención de las complicaciones asociadas a la
formación, crecimiento y posible ruptura de estas dilataciones anormales de la pared
arterial.
Mediante programas de diseño gráfico y la implementación de las metodologías
realizadas en trabajos previos al presente, se reconstruyeron nueve casos reales de
pacientes, entregados por el Instituto de Neurocirugía Asenjo, y se realizaron simulaciones
numéricas con el programa computacional ADINA® (Automatic Dynamic Incremental
Nonlinear Analysis), analizando los esfuerzos y deformaciones dados por la forma de la
geometría, los valores de presión interna del pulso sanguíneo y externa intracraneal, y por
el espesor y modelo de material utilizado en la pared arterial y en el aneurisma.
Los resultados muestran que, al considerar una geometría con espesor variable entre
arteria y aneurisma, no sólo se obtiene una distribución de esfuerzos diferente en
comparación a la simulación con espesor constante de aneurisma, sino también los valores
de esfuerzos y deformaciones alcanzados disminuyen en hasta un 76% en el aneurisma,
debido a la presencia de una arteria más gruesa, que además opone resistencia al
desplazamiento de la geometría. Por otro lado, al utilizar un modelo de material
diferenciado en las dos zonas principales de la geometría, se obtienen diferencias menores
al 6% en los resultados, al comparar con simulaciones que consideran la presencia de un
modelo único de aneurisma.
Se concluye entonces que las condiciones de simulación que describen de manera
más realista la situación estudiada, incluyen el uso del espesor adecuado en cada zona de la
geometría, siendo suficiente para una descripción rápida y acertada el uso de un modelo
hiper-elástico de aneurisma (o incluso su aproximación elástica) único en toda la geometría.
Se logró cuantificar además, el efecto de otras variables y decisiones al momento de
simular, en el estado de esfuerzos y deformaciones de las geometrías analizadas.
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Bacciaglia, Antonio <1993>. "Advanced voxel-based CAD modelling for FSI simulations for automotive structures design." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2022. http://amsdottorato.unibo.it/10181/1/Antonio_Bacciaglia_thesis.pdf.
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Additive Manufacturing (AM) is nowadays considered an important alternative to traditional manufacturing processes. AM technology shows several advantages in literature as design flexibility, and its use increases in automotive, aerospace and biomedical applications. As a systematic literature review suggests, AM is sometimes coupled with voxelization, mainly for representation and simulation purposes. Voxelization can be defined as a volumetric representation technique based on the model’s discretization with hexahedral elements, as occurs with pixels in the 2D image. Voxels are used to simplify geometric representation, store intricated details of the interior and speed-up geometric and algebraic manipulation. Compared to boundary representation used in common CAD software, voxel’s inherent advantages are magnified in specific applications such as lattice or topologically structures for visualization or simulation purposes. Those structures can only be manufactured with AM employment due to their complex topology. After an accurate review of the existent literature, this project aims to exploit the potential of the voxelization algorithm to develop optimized Design for Additive Manufacturing (DfAM) tools. The final aim is to manipulate and support mechanical simulations of lightweight and optimized structures that should be ready to be manufactured with AM with particular attention to automotive applications. A voxel-based methodology is developed for efficient structural simulation of lattice structures. Moreover, thanks to an optimized smoothing algorithm specific for voxel-based geometries, a topological optimized and voxelized structure can be transformed into a surface triangulated mesh file ready for the AM process. Moreover, a modified panel code is developed for simple CFD simulations using the voxels as a discretization unit to understand the fluid-dynamics performances of industrial components for preliminary aerodynamic performance evaluation. The developed design tools and methodologies perfectly fit the automotive industry’s needs to accelerate and increase the efficiency of the design workflow from the conceptual idea to the final product.
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Kim, Hyunsoon. "Coupled Adjoint-based Sensitivity Analysis using a FSI Method in Time Spectral Form." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/94132.
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A time spectral and coupled adjoint based sensitivity analysis of rotor blade is carried out in this study. The time spectral method is an efficient technique to solve unsteady periodic problems by transforming unsteady equation of motion to a steady state one. Due to the availability of the governing equations in the steady form, the steady form of the adjoint equations can be applied for the sensitivity analysis of the coupled fluid-structure system. An expensive computational time and memory requirement for the unsteady adjoint sensitivity analysis is thus avoided. A coupled analysis of fluid, structural, and flight dynamics is carried out through a CFD/CSD/CA coupling procedure that combines FSI analysis with enforced trim condition. Coupled sensitivity analysis results and their validations are presented and compared with aerodynamics only sensitivity analysis results. The fluid-structure coupled adjoint based sensitivity analysis will be applied to the shape optimization of a rotor blade in the future work. Minimization of required power is the objective of the optimization problem with constraints on thrust and drag of the rotor. The bump functions are considered as the design variables. Rotor blade shape changes are obtained by using the bump function on the surface of the airfoil sections along the span.Doctor of Philosophy
The work in this dissertation is motivated by the reducing the computational cost at the early design stage with guaranteed accuracy. In the research, the author proposes that the goal can be achieve through coupled adjoint based sensitivity analysis using a fluid structure interaction in time spectral form. Adjoint based sensitivity analysis is very efficient for solving design problems with a large number of design variables. The time spectral approach is used to overcome inefficient calculation of rotor flows by expressing flow and structural state variables as Fourier series with small number of harmonics. The accuracy and the efficiency of flow solver are examined by simulating UH-60A forward flight condition. A significant reduction in the computational cost is achieved by its Fourier series form of the periodic time response and the assumption of periodic steady state. A good agreement between time accurate and time spectral analysis is noted for the high speed forward flight condition of UH-60A configuration. Prediction from both methods also agree quite well with the experimental data. The adjoint based sensitivity analysis results are compared with the finite difference sensitivity analysis results. Even with presence of small discrepancies, these two results show a good agreement to each other. Coupled sensitivity analysis includes not only the effect of fluid state changes but also the contribution of structural deformation.
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Lindstam, Stefan [Verfasser]. "Das FSI Führungsstilinventar und das Integrative Führungsmodell : Universität Mannheim - Fakultät für Sozialwissenschaften / Stefan Lindstam." Berlin : epubli GmbH, 2015. http://www.epubli.de/.
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Novák, Lukáš. "Návrh technologie výroby zadané součásti pro podmínky školní dílny ÚST FSI VUT v Brně." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230986.
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Diploma thesis deals with design and implementation of manufacturing technology of a part which was given by company Frentech Aerospace s.r.o. Manufacturing technology is prepared for conditions of workshop of Department of Machining FME Brno UT (laboratory C2). Acquired knowledges are used for design of innovative manufacturing technology with cutting tools from company Pramet Tools, s.r.o. Manufacturing technologies of gained part are designed for alloy blank EN AW 6082. Technical-economical assessment of all manufacturing technologies is part of this thesis. Both of manufacturing technologies designed for laboratory C2 are assessed together and manufacturing technology given by company Frentech Aerospace s.r.o. is assessed alone due to using different blank material.
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Feilhauer, Michal. "Řešení dynamické odezvy vodohospodářských konstrukcí v interakci s kapalinou." Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-355595.
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Behaviour prediction of hydraulic steel structures with the view to surrounding influences in various design dispositions is a fundamental condition for operational reliability assessment of the analyzed construction. Reliable characteristics of construction behaviour defined by the specification of its movement within changes caused by time and environmental influences is of great importance. In currently used engineering mechanics formulation it concerns setting the response of the defined construction or its part to the given time variable mechanic load. Required response values, which are necessary for evaluation terminal dispositions of capacity and usability of the construction, are trans-location and tension, or values thence derived. Calculation is basic means for response prediction of construction. The thesis presented deals with complex multi-physical behaviour problems of water supply constructions in fluid structure interaction. There are presented various approaches to calculations of static and dynamic qualities of constructions. These approaches are divided into so called “direct method”, which is based on direct connection between two physical fields and the calculation is performed by the method of final elements, and so called “indirect method” , which is based on connection of two physical fields by means of various interfaces, which are described in this thesis. In case of indirect method, the calculation of running liquid is performed by the method of final volumes and the construction calculation is performed by the method of final elements. Within the scope of this thesis, static and dynamic responses of water supply constructions have been solved with the use of the above mentioned approaches. The results of the calculations in the scope of this thesis have been compared with the findings of performed experiments. The final part of the thesis describes the results and generalized findings gathered from the tasks by various approaches.
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Keyhan, Hooman. "Fluid structure interaction (FSI) based wind load modeling for dynamic analysis of overhead transmission lines." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=114457.
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Electricity is a crucial form of energy in our societies, and transmission lines are key elements to ensure the reliability of electric power grids. Continuity of service is the main preoccupation of electric utilities, and this continuity may be disrupted by a large variety of sources and accidents. Transmission lines, by their intrinsic topology, remain the grid components that are the most exposed to climatic sources of disruption.The most common and important source of dynamic loads on transmission lines results from wind effects on the towers and conductors. Conductors are particularly sensitive to wind effects as they are long and relatively flexible (compared to their supports) and are literally wind-catching structures in the power grid infrastructure. In cold climates, wind and ice have compounding effects on lines and give rise to the most severe design loading conditions. Therefore, accurate prediction of the wind pressure on overhead conductors is essential to conduct a reliable assessment of the line response, in terms of both electrical clearances and conductor loads transferred to supports. Spatial randomness of wind loads on overhead lines has already been addressed by stochastic analysis methods and is now taken into account in design with the use of so-called span factors. Further gains in wind load accuracy can be obtained by examining the physics of wind effects on conductors, in both non-iced and iced conditions, with improved predictions of lift and drag forces determined from fluid-structure interaction (FSI) analysis.The traditional design method to apply wind load on transmission lines is to convert the design wind speed to a static pressure through Bernoulli's equation where the pressure is proportional to the air density and the squared wind speed. In this approach the fluid-structure interaction of wind and line components is ignored: wind is considered as a quasi-static load on conductors and supports, while special instability effects due to particular wind conditions such as vortex shedding (Aeolian vibrations) and flutter (cable galloping) are accounted for separately with specific mitigation solutions if necessary.In gusty wind conditions with high turbulence intensity, conductors may experience large horizontal displacements that affect their surrounding wind flow. A physically accurate wind load evaluation on conductors is possible by computational wind-structure interaction analysis. To date, largely due to its high computational cost and the lack of experimental data to validate computational models, an advanced fluid-structure analysis framework for wind-cable interaction has not been developed. In this study a new approach based on FSI analysis to evaluate equivalent wind loads on conductors is developed. The first step in such an approach is accurate evaluation of wind pressure on conductor. For this purpose the FSI analysis is carried out in two dimensions where the detailed bare and iced conductor section geometry and surrounding air flow are modeled, considering a given incident wind speed. The conductor cross section is assumed to be supported on flexible supports to study the interaction between the conductor motion and the air flow. FSI analysis yields both the fluid and structure response. Of particular interest is the wind pressure field on the conductor section, which allows the computation of the resultant drag and lift forces. This process is repeated for several cross sections along the span and the resulting forces provide the effective span wise wind load distribution on the conductor. This wind loading is then used as input in a separate 3-D computational nonlinear dynamic analysis model to predict the line response. This dynamic analysis of the line section can be detailed to represent very realistic line sections including conductors, suspension links and supporting towers.Nos sociétés sont fortement dépendantes de l'électricité, et il ne fait pas de doute que la fonctionnalité des lignes de transport est déterminante pour assurer la fiabilité des réseaux électriques modernes. En effet, la continuité de l'approvisionnement en électricité reste la préoccupation majeure de toutes les compagnies d'électricité, et cette continuité du service peut être compromise par une multitude d'incidents ou d'accidents sur l'ensemble du réseau. Parmi toutes les sources possibles de charges dynamiques sollicitant les lignes de transport, celles provenant des effets du vent sur les pylônes et les conducteurs restent les plus fréquentes. Les conducteurs de lignes sont particulièrement vulnérables aux effets du vent car les portées sont longues et flexibles (comparé aux pylônes) et leur présence physique dans le réseau en font des structures exposées à toutes les intempéries qui peuvent survenir sur le territoire couvert. Cette vulnérabilité est encore plus grande dans les climats nordiques où les effets combinés du givrage atmosphérique et du vent créent des scénarios de charges de conception parmi les plus critiques et donc susceptibles de contrôler la conception finale des lignes. Il nous apparaît donc essentiel de comprendre la dynamique des fluides des effets du vent pour prédire avec réalisme et un degré de précision raisonnable la pression du vent exercée sur les conducteurs. Une meilleure évaluation des charges dues au vent permettrait par le fait même des prédictions plus réalistes de la réponse des lignes aux charges de vent, non seulement en terme de déplacements et dégagements électriques mais aussi en terme des charges nettes transférées aux pylônes par les conducteurs. La nature aléatoire des effets du vent sur les conducteurs a déjà fait l'objet de nombreuses études scientifiques et les méthodes d'analyse stochastique modernes permettent de cerner la question : les méthodes de conception simplifiées qui sont suggérées dans les normes et guides tiennent compte de ces effets en utilisant un coefficient de portée global qui ajuste à la baisse les efforts calculés au pylône sous des charges supposées synchrones et uniformes le long des conducteurs. Cette recherche ne concerne pas cet aspect de la question. Nous croyons que des gains de précision appréciables dans la prédiction des charges de vent sur les lignes sont possibles par une meilleure modélisation de la physique des effets du vent sur les conducteurs, dans les conditions givrées ou non, en utilisant les techniques d'analyse qui tiennent compte des interactions dynamiques fluide-structure. Ces interactions sont ignorées dans les méthodes d'analyse conventionnelles qui consistent simplement à calculer une pression statique proportionnelle à la vitesse carrée du fluide selon l'équation classique de Bernoulli. Bien sûr, les concepteurs ne négligent pas la considération des vibrations éoliennes ou du galop des conducteurs, mais ces phénomènes sont traités séparément et n'influencent pas le calcul des charges sur les pylônes. Dans cette recherche, nous nous intéressons aux conditions de vent de rafale avec grande turbulence qui caractérisent les tempêtes de vent. Ces vents forts et turbulents créent de grands déplacements des conducteurs qui modifient les conditions d'écoulement d'air. Une évaluation plus précise de ces conditions est possible par analyse computationnelle des interactions vent-conducteur.Les bases théoriques de la physique des phénomènes en présence sont connues mais aucun cadre d'application numérique n'a été proposé jusqu'à maintenant, en partie à cause des coûts numériques élevés mais aussi dû au manque de données expérimentales pouvant valider ces modèles computationnels.Nous avons développé un tel cadre d'analyse computationnelle dans cette recherche et l'avons illustré dans un cycle complet, du calcul des charges au calcul de la réponse d'une section de ligne, avec plusieurs exemples pratiques à chacune des étapes de développement
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Mahadevan, Sankar. "Developing a Vehicle Hydroplaning Simulation using Abaqus and CarSim." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/79699.
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Tires are the most influential component of the vehicle as they constitute the only contact between the vehicle and the road and have to generate and transmit forces necessary for the driver to control the vehicle. Hydroplaning is a phenomenon which occurs when a layer of water builds up between the tires of a vehicle and the road surface which leads to loss of traction that prevents the vehicle from responding to control inputs such as steering, braking or acceleration.
It has become an extremely important factor in the automotive and tire industry to study the factors affecting vehicle hydroplaning. Nearly 10-20% of road fatalities are caused by lack of traction on wet surfaces. The tire tread pattern, load, inflation pressure, slip and camber angles influence hydroplaning to a great extent. Finite Element Analysis, although computationally expensive, provides an excellent way to study such Fluid Structure Interactions (FSI) between the tire-water-road surfaces. Abaqus FSI CEL approach has been used to study tire traction with various vehicle configurations.
The tire force data obtained from the Finite Element simulations is used to develop a full vehicle hydroplaning model by integrating the relevant outputs with the commercially available vehicle dynamics simulation software, CarSim.Master of Science
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Miranda, Ramos Diego Alexander. "Estudio numérico de diferentes modelos de pared en aneurismas cerebrales." Tesis, Universidad de Chile, 2017. http://repositorio.uchile.cl/handle/2250/148539.
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Ingeniero Civil MecánicoEn el presente trabajo de título se estudia el comportamiento de aneurismas cerebrales, el cual es una patología provocada por el debilitamiento de las paredes en los vasos sanguíneos generando un estiramiento de la estructura con riesgo de ruptura. El objetivo principal de este trabajo consiste en el estudio comparativo a través de simulaciones computacionales FSI (Fluid Solid Interaction) con acople completo de 4 modelos de pared arteriales, 3 hiperlasticos (Valencia, Toth, Costalat) y uno elástico (Valencia Lineal), en 2 geometrías con aneurismas del tipo lateral y 2 terminales. Las variables estudiadas son la presión, los WSS (esfuerzos de corte), deformación y esfuerzos de Von Mises. Para esto se utiliza los software comerciales Ansys-Fluent y Ansys-Estructural. Los principales resultados mostraron que el modelo de Toth y Valencia Lineal tienen un comportamiento muy similar para las variables de estudio, mientras que Costalat y Valencia tienden a parecerse en menor medida. Con respecto a la presión, no se encontraron grandes diferencias entre los autores, comportándose de forma muy similar entre todos, tanto en magnitud como en comportamiento. La concentración de WSS se ubican en las mismas zonas para los 4 autores, difiriendo en magnitud, siendo Costalat el con mayores valores y Toth el con menores. Además, se observa que en las geometrías saculares estos tienden a concentrarse en el sector del cuello, mientras en los terminales a las salidos de los aneurismas. Las mayores deformaciones para todos los autores son siempre en el sector de los aneurismas, cambiando en magnitud para los diferentes modelos. Se obtiene que Toth es el autor con mayores deformaciones en promedio y Costalat el de menores. También se observa que los aneurismas laterales tienen en promedio un 55\% más de deformación que los terminales. Los esfuerzos de Von Mises son los que presentan mayores diferencias entre los autores, llegando incluso a valores de un 40\% entre ellos para los esfuerzos máximos, aunque ninguno supera los limites de ruptura. Costalat es el de mayores valores, mientras Toth el de menores. No se encuentran diferencias significativas entre las distintas geometrías. Por otro lado, se estudia el comportamiento de las simulaciones en general al dejar la pared rígida y con simulaciones FSI con acople en una dirección entre los programas. Resultando que tanto los WSS como los esfuerzos de Von Mises difieren significativamente en comparación a la simulación FSI con acople total. Finalmente, se concluye que para las variables de deformación, WSS y esfuerzos de Von Mises los distintos modelos de pared presentan comportamientos distintos para las simulaciones, mientras que para la presión no hay mayores diferencias.
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Bernardi, Giacomo. "Feasibility Study of a 3D CFD Solution for FSI Investigations on NREL 5MW Wind Turbine Blade." Thesis, KTH, Kraft- och värmeteknologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-159690.
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With the increase in length of wind turbine blades flutter is becoming a potential design constrain, hence the interest in computational tools for fluid-structure interaction studies. The general approach to this problem makes use of simplified aerodynamic computational tools. Scope of this work is to investigate the outcomes of a 3D CFD simulation of a complete wind turbine blade, both in terms of numerical results and computational cost. The model studied is a 5MW theoretical wind turbine from NREL. The simulation was performed with ANSYS-CFX, with different volume mesh and turbulence model, in steady-state and transient mode. The convergence history and computational time was analyzed, and the pressure distribution was compared to a high fidelity numerical result of the same blade. All the model studied were about two orders of magnitude lighter than the reference in computation time, while showing comparable results in most of the cases. The results were affected more by turbulence model than mesh density, and some turbulence models did not converge to a solution. In general seems possible to obtain good results from a complete 3D CFD simulation while keeping the computational cost reasonably low. Attention should be paid to mesh quality.
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Leger, Timothy James. "Development of an Unsteady Aeroelastic Solver for the Analysis of Modern Turbomachinery Designs." Wright State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=wright1283588070.
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Snyder, Troy Alan. "On Hydrodynamic Lubrication using Perturbed Reynolds equation and CFD-FSI: Static and Dynamic Characteristics of Compliant Marine Bearings." University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron157552061871739.
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Nunez, Ramirez Jorge. "A multi time-step partitioned approach for the coupling of SPH and FE methods for nonlinear FSI problems." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEI040/document.
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Dans le cadre de ce travail, une technique non-intrusive est proposée pour coupler la méthode Smoothed Particle Hydrodynamics (SPH) à la méthode des Eléments Finis afin de résoudre numériquement des problèmes dynamiques et non-linéaires d’interaction fluide-structure en permettant l’utilisation des pas de temps différents dans les deux domaines de calcul (fluide et solide). Ces développements sont motivés par le besoin de simuler numériquement des phénomènes rapides et très non-linéaires qui prennent en compte des impacts en se servant des intégrateurs temporels explicites dans chaque sous-domaine de calcul (Newmark explicite pour le solide et Runge-Kutta 2 pour le fluide). De ce fait, le pas de temps de stabilité est limité par des caractéristiques intrinsèques au modèle numérique du phénomène étudié et en conséquence, il devient important de pouvoir intégrer chaque sous-domaine numérique avec un pas de temps proche de son pas de temps de stabilité. Pour permettre d’utiliser un pas de temps proche du pas de temps de stabilité pour chaque sous-domaine, des méthodes de décomposition de domaines dual-Schur sont implémentées et validées pour des cas en 1-D, 2-D, et 3-D. Des simulations numériques d’impacts de cailloux sur des aubes des turbines hydrauliques sont aussi effectue´es afin de prédire le dommage que cet évènement peut engendrerA method to couple smoothed particle hydrodynamics and finite elements methods for nonlinear transient fluid–structure interaction simulations by adopting different time-steps depending on the fluid or solid sub-domains is proposed. These developments were motivated by the need to simulate highly non-linear and sudden phenomena that take into acount solid impacts and hence require the use of explicit time integrators on both sub-domains (explicit Newmark for the solid and Runge–Kutta 2 for the fluid). However, due to critical time-step required for the stability of the explicit time integrators in, it becomes important to be able to integrate each sub-domain with a different time-step while respecting the features that a previously developed mono time-step coupling algorithm offered. For this matter, a dual-Schur decomposition method originally proposed for structural dynamics was considered, allowing to couple time integrators of the Newmark family with different time-steps with the use of Lagrange multipliers
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Holder, Justin. "Fluid Structure Interaction in Compressible Flows." University of Cincinnati / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin159584692691518.
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Conger, Michael Anthony. "Validation of CFD-MBD FSI for high-gidelity simulations of full-scale WAM-V sea-trials with suspended payload." Thesis, University of Iowa, 2015. https://ir.uiowa.edu/etd/1960.
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High-fidelity CFD-MBD FSI (Computational Fluid Dynamics - Multi Body Dynamics Fluid-Structure Interaction) code development and validation by full-scale experiments is presented, for a novel hull form, WAM-V (Wave Adaptive Modular Vessel). FSI validation experiments include cylinder drop with suspended mass and 33 ft WAM-V sea-trials. Calm water and single-wave sea-trails were with the original suspension, while the rough-water testing was with a second generation suspension. CFDShip-Iowa is used as CFD solver, and is coupled to Matlab Simulink MBD models for cylinder drop and second generation WAM-V suspension. For 1DOF cylinder drop, CFD verification and validation (V&V) studies are carried out including grid and time-step convergence. CFD-MBD results for 2DOF cylinder drop show that 2-way coupling is required to capture coupled physics. Overall, 2-way results are validated with an overall average error value of E=5.6%DR for 2DOF cylinder drop. For WAM-V in calm water, CFD-MBD 2-way results for relative pod angle are validated with E=14.2%DR. For single-wave, CFD-MBD results show that 2-way coupling significantly improves the prediction of the peak amplitude in pontoon motions, while the trough amplitudes in suspension motions are under-predicted. The current CFD-MBD 2-way results for single-wave are validated with E=17%DR. For rough-water, simulations are carried out in regular head waves representative of the irregular seas. CFD-MBD 2-way results are validation with E=23%D for statistical values and the Fourier analysis results, which is reasonable given the differences between simulation waves and experiments.
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Buchschmid, Martin [Verfasser], Gerhard H. [Akademischer Betreuer] Müller, Harry [Akademischer Betreuer] Grundmann, and Peter [Akademischer Betreuer] Rentrop. "ITM-Based FSI-Models for Rooms with Absorptive Boundaries / Martin Buchschmid. Gutachter: Harry Grundmann ; Peter Rentrop. Betreuer: Gerhard H. Müller." München : Universitätsbibliothek der TU München, 2011. http://d-nb.info/1019588004/34.
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Van, Zyl Marilize. "Prediction of flow-induced vibration in shell-and-tube heat exchangers." Diss., University of Pretoria, 2004. http://hdl.handle.net/2263/28055.
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Please read the abstract (Summary) in the 00front part of this documentDissertation (M Eng (Mechanical Engineering))--University of Pretoria, 2006.
Mechanical and Aeronautical Engineering
unrestricted
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Javadzadegan, Ashkan. "Computational fluid dynamics modelling of atherosclerotic coronary arteries and abdominal aortic aneurysms." Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/11735.
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This thesis aimed to use three-dimensional quantitative coronary angiography (3D-QCA), computational fluid dynamics (CFD), fluid-structure interaction (FSI) and particle image velocimetry (PIV) techniques in idealised and realistic coronary artery models based on data from patients in order to investigate the relation between haemodynamic forces and lesion morphology. The first aim was to assess the effect of lesion severity and eccentricity on important haemodynamic factors including flow recirculation and shear stress using CFD and PIV. The results showed that the extent of flow recirculation is much more sensitive to mild changes in the severity of intermediate stenoses than is peak shear. The second aim was to find the correlation between fractional flow reserve (FFR), a gold standard to measure the functional significance of coronary stenoses, lesion eccentricity and vessel distensibility using 3D-QCA and FSI methods. The results demonstrated that the coronary arteries with similar lesion morphology but different vessel distensibility are likely to experience different FFR. The third aim was to explore the impact of degree of freedom of coronary arteries on important haemodynamic factors. The results showed that modelling of coronary arteries as rigid vessels could result in treating a non-significant lesion as significant because the rigidity assumption overestimates the amount of flow abnormalities in coronary arteries. Overall, the greater the degree of freedom of movement, the lower the maximum wall shear stress (WSS) and the smaller the area of low WSS. Last but not least, the effect of spiral flow on haemodynamic parameters in an elastic model of abdominal aortic aneurysm (AAA) was investigated. The results demonstrated that neglecting the spiral effects of flow in the modelling of AAAs can result in overestimation of wall stress and the artery wall expansion rate.
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Jurina, Marek. "Aerodynamická analýza poddajného křídla kluzáku." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-377517.
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This thesis deals with determination of effect of wing flexibility on load distribution. FSI analysis using modal superposition was used for determination of effect of wing flexibility. Analysis was verified by analytic calculation. Differences of load distribution, between rigid and flexible wing, was determined for the selected flight regimes. Change of the bending moment was up to 3,9 %. Thesis shows importance of including effect of wing flexibility for sailplane design.
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Eltvik, Mette. "Sediment erosion in Francis turbines." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for energi- og prosessteknikk, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-22755.
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Sediment erosion is a major challenge for run-of-river power plants, especially during flood periods. Due to the high content of hard minerals such as quartz and feldspar carried in the river, substantial damage is observed on the turbine components. Material is gradually removed, thus the efficiency of the turbine decreases and the operating time of the turbine reduces. Hydro power plants situated in areas with high sediment concentration suffer under hard conditions, where turbine components could be worn out after only a short period of three months. This short life expectation causes trouble for energy production since the replacement of new turbine parts is a time consuming and costly procedure. It is desirable to design a Francis runner which will withstand sediment erosion better than the traditional designs. The literature states that an expression for erosion is velocity to the power of three. By reducing the relative velocities in the runner by 10%, the erosion will decrease almost 30%. The objective is to improve the design of a Francis turbine which operates in rivers with high sediment concentration, by looking at the design parameters in order to reduce erosion wear. A Francis turbine design tool was developed to accomplish the parameter study. In the search for an optimized Francis runner, several design proposals were compared against a reference design by evaluating the turbine’s performance. The hydraulic flow conditions and the prediction of erosion on the turbine components are simulated by analyzing the models with a Computational Fluid Dynamic (CFD) tool. A Fluid Structure Interaction (FSI) analysis ensures that the structural integrity of the design is within a desired value. Results from this research show that it is feasible to design a runner with an extended lifetime, without affecting the main dimensions and hydraulic efficiency.
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Ledermann, Molina Darren Andrés. "Modelación de Aneurismas Cerebrales: Simulación Fluidodinámica y Estructural." Tesis, Universidad de Chile, 2007. http://www.repositorio.uchile.cl/handle/2250/104692.
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Suliman, Ridhwaan. "Development of parallel strongly coupled hybrid fluid-structure interaction technology involving thin geometrically non-linear structures." Diss., University of Pretoria, 2012. http://hdl.handle.net/2263/24288.
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This work details the development of a computational tool that can accurately model strongly-coupled fluid-structure-interaction (FSI) problems, with a particular focus on thin-walled structures undergoing large, geometrically non-linear deformations, which has a major interest in, amongst others, the aerospace and biomedical industries. The first part of this work investigates improving the efficiency with which a stable and robust in-house code, Elemental, models thin structures undergoing dynamic fluid-induced bending deformations. Variations of the existing finite volume formulation as well as linear and higher-order finite element formulations are implemented. The governing equations for the solid domain are formulated in a total Lagrangian or undeformed conguration and large geometrically non-linear deformations are accounted for. The set of equations is solved via a single-step Jacobi iterative scheme which is implemented such as to ensure a matrix-free and robust solution. Second-order accurate temporal discretisation is achieved via dual-timestepping, with both consistent and lumped mass matrices and with a Jacobi pseudo-time iteration method employed for solution purposes. The matrix-free approach makes the scheme particularly well-suited for distributed memory parallel hardware architectures. Three key outcomes, not well documented in literature, are highlighted: the issue of shear locking or sensitivity to element aspect ratio, which is a common problem with the linear Q4 finite element formulation when subjected to bending, is evaluated on the finite volume formulations; a rigorous comparison of finite element vs. finite volume methods on geometrically non-linear structures is done; a higher-order finite volume solid mechanics procedure is developed and evaluated. The second part of this work is concerned with fluid-structure interaction (FSI) modelling. It considers the implementation and coupling of a higher order finite element structural solver with the existing finite volume fluid-flow solver in Elemental. To the author’s knowledge, this is the first instance in which a strongly-coupled hybrid finite element–finite volume FSI formulation is developed. The coupling between the fluid and structural components with non-matching nodes is rigorously assessed. A new partitioned fluid-solid interface coupling methodology is also developed, which ensures stable partitioned solution for strongly-coupled problems without any additional computational overhead. The solver is parallelised for distributed memory parallel hardware architectures. The developed technology is successfully validated through rigorous temporal and mesh independent studies of representative two-dimensional strongly-coupled large-displacement FSI test problems for which analytical or benchmark solutions exist.Dissertation (MEng)--University of Pretoria, 2012.
Mechanical and Aeronautical Engineering
unrestricted
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Freiwald, Michal. "Výpočtové modelování interakce proudící krve s trubicí tepny s ateromem." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-443763.
Full textAbstract:
Předložená diplomová práce se zabývá interakcí mezi proudící krví a krční tepnou, obsahující aterosklerotický plat, za pomoci konečnoprvkové fluid-structure interaction analýzy. První část práce obsahuje souhrn teoretických poznatků, sestávající z kardiovaskulárního systému, cév, souvisejících konstitutivních modelů, reologie krve a úvodu do teorie proudění. Dále je v práci obsažen stručný souhrn současného poznání výpočtového modelování v této oblasti, s důrazem na strukturní a fluid-structure interaction analýzy v oblasti krční tepny, a na použité konstitutivní modely. Experimentální část se soustředí na tvorbu zjednodušeného modelu krční tepny, obsahující aterosklerotický plat, a na tvorbu odpovídajícího modelu krve. Oba modely poté společně vstupují do fluid-structure interaction analýzy, která si klade za cíl pochopit důsledky pulzujícího toku krve na stěnu tepny a na růst aterosklerotického plátu; primárními zkoumanými veličinami jsou první hlavní napětí na stěně tepny, celková deformace stěny tepny, časově zprůměrovaná hodnota smykového napětí na stěně tepny a oscilační smykový index. Všechny výsledky jsou porovnány napříč několika typy analýz, tak aby bylo možné zhodnotit rozdíly a důsledky zvoleného přístupu. Součástí práce je také zjednodušená parametrická studie, která porovnává vliv rostoucího procenta stenózy na vyhodnocované veličiny. V poslední částí práce jsou zhodnoceny výsledky, její limitace a další možnosti výzkumu v této oblasti.
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Fisch, Rupert Johannes [Verfasser], Kai-Uwe [Akademischer Betreuer] Bletzinger, Riccardo [Akademischer Betreuer] Rossi, and Fabian [Akademischer Betreuer] Duddeck. "Code Verification of Partitioned FSI Environments for Lightweight Structures / Rupert Johannes Fisch. Gutachter: Riccardo Rossi ; Fabian Duddeck ; Kai-Uwe Bletzinger. Betreuer: Kai-Uwe Bletzinger." München : Universitätsbibliothek der TU München, 2014. http://d-nb.info/1062701119/34.
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Fisch, Rupert [Verfasser], Kai-Uwe [Akademischer Betreuer] Bletzinger, Riccardo [Akademischer Betreuer] Rossi, and Fabian [Akademischer Betreuer] Duddeck. "Code Verification of Partitioned FSI Environments for Lightweight Structures / Rupert Johannes Fisch. Gutachter: Riccardo Rossi ; Fabian Duddeck ; Kai-Uwe Bletzinger. Betreuer: Kai-Uwe Bletzinger." München : Universitätsbibliothek der TU München, 2014. http://nbn-resolving.de/urn:nbn:de:bvb:91-diss-20141115-1222442-0-1.
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Pons, Cots Ramon Maria. "Computational analysis of fluid dynamics at the asceding thoracic aorta in Marfan syndrome patients." Doctoral thesis, Universitat Ramon Llull, 2020. http://hdl.handle.net/10803/669234.
Full textAbstract:
Els aneurismes aòrtics són una dilatació progressiva i irreversible de la paret aòrtica, que pot causar la ruptura o dissecció dels vasos, el que resulta en una pèrdua catastròfica de sang que condueix a la mort. El tractament farmacològic inicial se centra en aturar el creixement per prevenir la ruptura, però requereix una reparació invasiva oberta o una reparació endovascular en pacients en risc. El maneig del pacient i l'estratificació de risc després del diagnòstic són crítics, especialment en l'aorta ascendent, ja que actualment no hi ha tractaments endovasculars disponibles. Segons les directrius actuals, el diàmetre aòrtic màxim és l'únic criteri geomètric o fluidodinàmic específic del pacient acceptat com a predictor clínic del risc de ruptura. No obstant això, l'anormal fluidodinàmica en l'aorta ascendent s'ha reportat àmpliament com una possible font d'aneurismes aòrtics i la seva comprensió podria millorar l'avaluació del risc del pacient.
En aquest estudi, es va avaluar la fluidodinàmica en aortes de controls sans i pacients amb síndrome de Marfan. Per fer això, hem comparat el rendiment de les simulacions de dinàmica de fluids computacional i d'interacció fluid-estructura utilitzant imatges clíniques com a condicions específiques del pacient. També hem dissenyat un sistema in vitro que podria exposar les cèl·lules endotelials aòrtiques humanes a un entorn fluidodinàmic que imita el de les simulacions aòrtiques.
L'estudi ha revelat, en pacients Marfan, que considerà l'elasticitat de la paret en les simulacions és essencial per obtenir amb precisió els valors fluidodinàmics que tenen el potencial d'estratificar aquests pacients. En aquest sentit, les simulacions d'interacció fluid-estructura han superat la fluidodinàmica computacional clàssica a un cost computacional moderat. Com a resultat d'aquest estudi, un paràmetre adimensional, la relació d'esforç tallant, ha determinat el seu potencial com a marcador de progressió d'aneurisma en pacients amb Marfan.Los aneurismas aórticos son una dilatación progresiva e irreversible de la pared aórtica, que puede causar la ruptura o disección de los vasos, lo que resulta en una pérdida catastrófica de sangre que conduce a la muerte. El tratamiento farmacológico inicial se centra en detener el crecimiento para prevenir la ruptura, pero se requiere una reparación invasiva abierta o una reparación endovascular en pacientes en riesgo. El manejo del paciente y la estratificación del riesgo después del diagnóstico son críticos, especialmente en la aorta ascendente, ya que actualmente no hay tratamientos endovasculares disponibles. Según las directrices actuales, el diámetro aórtico máximo es el único criterio geométrico o fluidodinámico específico del paciente aceptado como predictor clínico del riesgo de ruptura. Sin embargo, la anormal fluidodinámica en la aorta ascendente se ha reportado ampliamente como una posible fuente de aneurismas aórticos y su comprensión podría mejorar la evaluación del riesgo del paciente. En este estudio, se evaluó la fluidodinámica en aortas de controles sanos y pacientes con síndrome de Marfan. Para hacer esto, hemos comparado el rendimiento de las simulaciones de dinámica de fluidos computacional y de interacción fluido-estructura utilizando imágenes clínicas como condiciones específicas del paciente. También hemos diseñado un sistema in vitro que podría exponer las células endoteliales aórticas humanas a un entorno fluidodinámico que imita el de las simulaciones aórticas. El estudio ha revelado, en pacientes Marfan, que considerar la elasticidad de la pared en las simulaciones es esencial para obtener con precisión los valores dinámicos de los fluidos que tienen el potencial de estratificar a estos pacientes. En este sentido, las simulaciones de interacción fluido-estructura han superado la fluidodinámica computacional clásica a un costo computacional moderado. Como resultado de este estudio, un parámetro adimensional, la relación de esfuerzo cortante, ha demostrado su potencial como marcador de progresión de aneurisma en pacientes con Marfan.
Aortic aneurysms are a progressive and irreversible dilation of the aortic wall, which can lead to vessel rupture or dissection, resulting in catastrophic blood loss leading to death. Initial pharmacological treatment is focused on growth arrest to prevent rupture, but invasive open repair or endovascular repair are required in patients at risk. Patient management and risk stratification after diagnosis are critical, especially in the ascending aorta since no endovascular treatments are currently available. According to current guidelines, maximum aortic diameter is the only patient-specific geometrical or fluidodynamic criterion accepted as clinical rupture risk predictor. However, abnormal fluid dynamics at the ascending aorta have been widely reported as potential origin of aortic aneurysms and their understanding could improve the risk assessment of patients. In this study, the fluid dynamics of aortae from healthy controls and patients with Marfan syndrome have been evaluated. To do so, we have compared the performance of computational fluid dynamics and fluid-structure interaction simulations using clinical imaging as patient-specific inputs. We have also designed an in vitro system that could expose human aortic endothelial cells to a fluidodynamic environment that mimics that of aortic simulations. The study has revealed, in Marfan patients, that considering the wall elasticity in simulations is critical to derive precisely fluid dynamic values that hold the potential to stratify such patients. In this sense, fluid-structure interaction simulations have outperformed classic computational fluid dynamics at a moderate computational cost. As a result of this study, a dimensionless parameter, the shear stress ratio, has shown its potential as marker of aneurysm progression in Marfan patients.
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Figueroa, Venegas Hernán Alejandro. "Análisis de Sensibilidad en Simulaciones de Aneurismas Cerebrales Considerando Interacción Fluido Estructura." Tesis, Universidad de Chile, 2008. http://repositorio.uchile.cl/handle/2250/104987.
Full textAbstract:
El presente trabajo de título forma parte del proyecto FONDECYT Flow Dynamics and
Arterial Wall Interaction in Realistic Cerebral Aneurysm Models. El principal objetivo de
este trabajo es optimizar la metodología de simulación de la mecánica de aneurismas
cerebrales desarrollada en trabajos anteriores [4],[5] en los siguientes sentidos: crear una
metodología de reconstrucción para dotar a las geometrías de espesor variable y cuantificar
la sensibilidad de los resultados al variar el modelo constitutivo del material de la pared
arterial, la cantidad de sifones de la vasculatura precedente al aneurisma, la condición de
salida del flujo y el espesor de la pared. El primer objetivo se logró en colaboración con Rojo
[2]. Para cumplir el segundo objetivo, se seleccionó uno de los nueve casos reconstruidos en
este trabajo de título y se realizaron tres simulaciones estructurales puras, tres simulaciones
CFD puras y cinco simulaciones FSI con el programa ADINA 8.3®.
Mediante las simulaciones se pudo hallar la proporción en que diferían los resultados
al variar los parámetros mecánicos antes mencionados. Se concluyó que la utilización de
un modelo elástico equivalente es suficientemente buena aproximación para simular la
mecánica de la pared arterial. Por otro lado, se concluyó que los resultados fluidodinámicos
están fuertemente influenciados por la creación de flujo secundario producto de la curvatura
de la vasculatura precedente al aneurisma. Al realizar las simulaciones, se debe considerar
al menos un sifón suficientemente curvo en la geometría.
Los resultados de las simulaciones FSI indican que las diferencias más grandes que
se producen al variar cualquier parámetro se hallan en el sólido, de hecho los resultados
fluidodinámicos, en su gran mayoría, no superan el 10 %. Por otro lado, el parámetro que
genera mayor sensibilidad en los resultados es el espesor de la pared. Esta variable produce
diferencias cercanas al 60% en el sólido, mientras que la variación de la condición de
presión o la elasticidad de la pared, tan sólo producen diferencias del orden del 30 %.
Se concluyó que la simulación más precisa desarrollada es la FSI que considera
modelo de pared elástica Seshaiyer equivalente, presión normal a la salida y espesor
de pared variable. En general, bajo esta metodología los esfuerzos y deformaciones son
sobreestimados, mientras que el esfuerzo de corte en la pared es subestimado, lo cual la
convierte en una prueba conservadora del riesgo de ruptura.
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Mudrich, Jaime. "Development of a Coupling Model for Fluid-Structure Interaction using the Mesh-free Finite Element Method and the Lattice Boltzmann Method." FIU Digital Commons, 2013. http://digitalcommons.fiu.edu/etd/964.
Full textAbstract:
In the presented thesis work, the meshfree method with distance fields was coupled with the lattice Boltzmann method to obtain solutions of fluid-structure interaction problems. The thesis work involved development and implementation of numerical algorithms, data structure, and software. Numerical and computational properties of the coupling algorithm combining the meshfree method with distance fields and the lattice Boltzmann method were investigated. Convergence and accuracy of the methodology was validated by analytical solutions.
The research was focused on fluid-structure interaction solutions in complex, mesh-resistant domains as both the lattice Boltzmann method and the meshfree method with distance fields are particularly adept in these situations. Furthermore, the fluid solution provided by the lattice Boltzmann method is massively scalable, allowing extensive use of cutting edge parallel computing resources to accelerate this phase of the solution process. The meshfree method with distance fields allows for exact satisfaction of boundary conditions making it possible to exactly capture the effects of the fluid field on the solid structure.
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Araya, Aburto Sebastián Andrés. "Simulación de la Hemodinámica en Modelos de Aneurismas Cerebrales Incluyendo la Interacción Fluido-Estructura." Tesis, Universidad de Chile, 2008. http://www.repositorio.uchile.cl/handle/2250/104872.
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Boqvist, Emil. "Investigation of a swing check valve using CFD." Thesis, Linköpings universitet, Mekanisk värmeteori och strömningslära, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-110751.
Full textAbstract:
This master’s thesis is made to increase the understanding of the dynamic characteristics of a typical large swing check valve used in a system that transports pressurized water to a reactor tank.3D FSI-simulations are performed for a number of transients in order to study the dynamic characteristics their dependence of the deceleration rate. The purpose is to find information about the dynamics that could be used in a future improvement of a 1D-model.Steady state simulations are performed for angles in the whole spectrum. Seven transient FSI-simulations with different constantly decelerating flows from 630 kg/s2 (6.7 m/s2) to 40 320 kg/s2 (430 m/s2) have been performed. The pressure on the disc caused by the hydraulic torque is integrated and the corresponding torque contribution, together with the weight torque, is used in the second law of motion to calculate the movement of the disc throughout the transients.Steady state simulations yield the pressure drop over the valve, which could be compared with field measurements in order to validate the CFD-simulations. Comparison of the pressure distribution on the disc for the steady state and transient simulations shows the importance of taking the disc angular velocity into account when modelling in 1D. Correlations between the angle, angular velocity, torque and mass flow are obtained from the transient FSI-simulations. Torque coefficients according to (Li & Liou, Vol. 125) are also brought out from the simulated transients, but in order to create a model in line with this approach further simulations have to be performed. A prediction of the pressure rise that occurs when a swing check valve closes in backward flow according to the Joukowsky equation is brought out and gives an idea of the loadings that the system has to be able to handle.
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Mowat, Andrew Gavin Bradford. "Modelling of non-linear aeroelastic systems using a strongly coupled fluid-structure-interaction methodology." Diss., University of Pretoria, 2011. http://hdl.handle.net/2263/30521.
Full textAbstract:
The purpose of this study was to develop a robust fluid-structure-interaction (FSI) technology that can accurately model non-linear flutter responses for sub- and transonic fluid flow. The Euler equation set governs the fluid domain, which was spatially discretised by a vertex-centred edge-based finite volume method. A dual-timestepping method was employed for the purpose of temporal discretisation. Three upwind schemes were compared in terms of accuracy, efficiency and robustness, viz. Roe, HLLC (Harten-Lax-Van Leer with contact) and AUSM+-up Advection Up-stream Splitting Method). For this purpose, a second order unstructured MUSCL (Monotonic Upstream-centred Scheme for Conservation Laws) scheme, with van Albada limiter, was employed. The non-linear solid domain was resolved by a quadratic modal reduced order model (ROM), which was compared to a semi-analytical and linear modal ROM. The ROM equations were solved by a fourth order Runge-Kutta method. The fluid and solid were strongly coupled in a partitioned fashion with the information being passed at solver sub-iteration level. The developed FSI technology was verified and validated by applying it to test cases found in literature. It was demonstrated that accurate results may be obtained, with the HLLC upwind scheme offering the best balance between accuracy and robustness. Further, the quadratic ROM offered significantly improved accuracy when compared to the linear method.Dissertation (MEng)--University of Pretoria, 2011.
Mechanical and Aeronautical Engineering
unrestricted
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Carvalho, Jeane Batista de [UNESP]. "Estudo numérico hemodinâmico de um aneurisma na vizinhança de uma bifurcação arterial tridimensional." Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/150730.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Nas últimas décadas, há uma crescente preocupação em mensurar os parâmetros dinâmicos do sangue, dadas as imensas perdas de vidas por doenças cardiovasculares sendo, muitas delas, por aneurismas. A formação e desenvolvimento de um aneurisma é, predominantemente, degenerativo e provém de uma complexa interação entre os efeitos biológicos da parede arterial, os estímulos de escoamento e tensões provenientes da hemodinâmica. A tensão cisalhante na parede e o cíclico campo de pressão são um dos principais fatores responsáveis pela formação e crescimento de um aneurisma. Logo, há a necessidade de se conhecer os campos de velocidades e pressão além das tensões cisalhantes e efetivas na parede. Uma análise numérica é mais promissora que uma experimental. Uma análise experimental in-vivo possui impasses éticos e morais, sem contar a necessidade de um grande investimento. Outra vantagem de um estudo numérico é a disponibilidade de softwares livres de extração de tomografias que permite a extração da geometria sem a necessidade de um método invasivo que ocorreria em estudo experimental in vivo. Portanto com o auxílio de simulações numéricas (Ansys®), considerando o efeito multi-física de interação fluido estrutura (FSI) pela metodologia de elementos e volumes finitos foi possível verificar o efeito dos fatores que levam a formação e crescimento de aneurisma na aorta abdominal. Os aneurismas estudados foram modelos geométricos e reais sendo um dos reais obtidos através de imagens DICOM.
In recent decades, there is growing concern in measuring the dynamic parameters of the blood, given the immense loss of life from cardiovascular disease in human history, including, aneurysms. The formation and development of an aneurysm is predominantly degenerative and results from a complex interaction between the biological effects of the arterial wall and the flow and stress effects from hemodynamics. The stress in the wall and in the cyclic field of pressure is one of the main factors for the formation and growth of an aneurysm that degenerates until its rupture. Therefore, it is necessary to know the velocity and pressure fields as well as the shear stress and effective stress on the wall. A numerical analysis is more promising than an experimental one since an in-vivo experimental analysis has ethical and moral impasses, not counting the need for a large investment. Another advantage of a numerical study is the availability of free softwares for tomography analysis that allows the extraction of the geometry without the need for an invasive method that would occur in an in vivo experimental study. Therefore, with the aid of numerical simulations (Ansys®), considering the multi-physical effect of fluid structure interaction (FSI) by the methodology of finite elements and finite volumes it was possible to verify the effect of factors that lead to the formation and growth of abdominal aortic aneurysm. The studied aneurysms came from geometric models and from real examples, being one of the real ones obtained through DICOM images.
CNPq: 131153/2015-3
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Carvalho, Jeane Batista de. "Estudo numérico hemodinâmico de um aneurisma na vizinhança de uma bifurcação arterial tridimensional /." Ilha Solteira, 2017. http://hdl.handle.net/11449/150730.
Full textAbstract:
Orientador: João Batista Campos SilvaResumo: Nas últimas décadas, há uma crescente preocupação em mensurar os parâmetros dinâmicos do sangue, dadas as imensas perdas de vidas por doenças cardiovasculares sendo, muitas delas, por aneurismas. A formação e desenvolvimento de um aneurisma é, predominantemente, degenerativo e provém de uma complexa interação entre os efeitos biológicos da parede arterial, os estímulos de escoamento e tensões provenientes da hemodinâmica. A tensão cisalhante na parede e o cíclico campo de pressão são um dos principais fatores responsáveis pela formação e crescimento de um aneurisma. Logo, há a necessidade de se conhecer os campos de velocidades e pressão além das tensões cisalhantes e efetivas na parede. Uma análise numérica é mais promissora que uma experimental. Uma análise experimental in-vivo possui impasses éticos e morais, sem contar a necessidade de um grande investimento. Outra vantagem de um estudo numérico é a disponibilidade de softwares livres de extração de tomografias que permite a extração da geometria sem a necessidade de um método invasivo que ocorreria em estudo experimental in vivo. Portanto com o auxílio de simulações numéricas (Ansys®), considerando o efeito multi-física de interação fluido estrutura (FSI) pela metodologia de elementos e volumes finitos foi possível verificar o efeito dos fatores que levam a formação e crescimento de aneurisma na aorta abdominal. Os aneurismas estudados foram modelos geométricos e reais sendo um dos reais obtidos através de imagens DICOM... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: In recent decades, there is growing concern in measuring the dynamic parameters of the blood, given the immense loss of life from cardiovascular disease in human history, including, aneurysms. The formation and development of an aneurysm is predominantly degenerative and results from a complex interaction between the biological effects of the arterial wall and the flow and stress effects from hemodynamics. The stress in the wall and in the cyclic field of pressure is one of the main factors for the formation and growth of an aneurysm that degenerates until its rupture. Therefore, it is necessary to know the velocity and pressure fields as well as the shear stress and effective stress on the wall. A numerical analysis is more promising than an experimental one since an in-vivo experimental analysis has ethical and moral impasses, not counting the need for a large investment. Another advantage of a numerical study is the availability of free softwares for tomography analysis that allows the extraction of the geometry without the need for an invasive method that would occur in an in vivo experimental study. Therefore, with the aid of numerical simulations (Ansys®), considering the multi-physical effect of fluid structure interaction (FSI) by the methodology of finite elements and finite volumes it was possible to verify the effect of factors that lead to the formation and growth of abdominal aortic aneurysm. The studied aneurysms came from geometric models and from real examples... (Complete abstract click electronic access below)
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