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Artykuły w czasopismach na temat "Strongly coupled fluid-structure interaction model"
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Vierendeels, J., K. Dumont i P. R. Verdonck. "A partitioned strongly coupled fluid-structure interaction method to model heart valve dynamics". Journal of Computational and Applied Mathematics 215, nr 2 (czerwiec 2008): 602–9. http://dx.doi.org/10.1016/j.cam.2006.04.067.
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Suliman, Ridhwaan, i Oliver Oxtoby. "A Quadratic Elasticity Formulation for Dynamic Interacting Structures in Flow". MATEC Web of Conferences 347 (2021): 00033. http://dx.doi.org/10.1051/matecconf/202134700033.
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The deformation of slender elastic structures due to the motion of surrounding fluid is a common multiphysics problem encountered in many applications. In this work we detail the development of a numerical model capable of solving such strongly-coupled fluid-structure interaction problems, and analyse the dynamic behaviour of multiple interacting bodies under fluid loading. In most fluid-structure interaction problems the deformation of slender elastic bodies is significant and cannot be described by a purely linear analysis. We present a new formulation to model these larger displacements. By extending the standard modal analysis technique for linear structural analysis, the governing equations and boundary conditions are updated to account for non-linear terms and a new modal formulation with quadratic modes is derived. The quadratic modal approach is tested on standard benchmark problems of increasing complexity and compared with analytical and full non-linear numerical solutions. An analysis of the dynamic interactions between multiple finite plates in various configurations under fluid loading, as well as the effects of the spacing between the structures, is also conducted. Numerical results are compared with theoretical and experimental approaches. The inverted hydrodynamic drafting effect of elastic bodies in an in-line configuration can be confirmed from our numerical simulations.
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Girfoglio, Michele, Annalisa Quaini i Gianluigi Rozza. "Fluid-structure interaction simulations with a LES filtering approach in solids4Foam". Communications in Applied and Industrial Mathematics 12, nr 1 (1.01.2021): 13–28. http://dx.doi.org/10.2478/caim-2021-0002.
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Abstract The goal of this paper is to test solids4Foam, the fluid-structure interaction (FSI) toolbox developed for foam-extend (a branch of OpenFOAM), and assess its flexibility in handling more complex flows. For this purpose, we consider the interaction of an incompressible fluid described by a Leray model with a hyperelastic structure modeled as a Saint Venant-Kirchho material. We focus on a strongly coupled, partitioned fluid-structure interaction (FSI) solver in a finite volume environment, combined with an arbitrary Lagrangian-Eulerian approach to deal with the motion of the fluid domain. For the implementation of the Leray model, which features a nonlinear differential low-pass filter, we adopt a three-step algorithm called Evolve-Filter-Relax. We validate our approach against numerical data available in the literature for the 3D cross flow past a cantilever beam at Reynolds number 100 and 400.
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MANGANO, G., G. MIELE i V. PETTORINO. "COUPLED QUINTESSENCE AND THE COINCIDENCE PROBLEM". Modern Physics Letters A 18, nr 12 (20.04.2003): 831–42. http://dx.doi.org/10.1142/s0217732303009940.
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We consider a model of interacting cosmological constant/quintessence, where dark matter and dark energy behave as, respectively, two coexisting phases of a fluid, a thermally excited Bose component and a condensate, respectively. In a simple phenomenological model for the dark components interaction we find that their energy density evolution is strongly coupled during the universe evolution. This feature provides a possible way out for the coincidence problem affecting many quintessence models.
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Joosten, M. M., W. G. Dettmer i D. Perić. "Analysis of the block Gauss-Seidel solution procedure for a strongly coupled model problem with reference to fluid-structure interaction". International Journal for Numerical Methods in Engineering 78, nr 7 (14.05.2009): 757–78. http://dx.doi.org/10.1002/nme.2503.
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Tiwari, Sanat, Vikram Dharodi, Amita Das, Predhiman Kaw i Abhijit Sen. "Kelvin-Helmholtz instability in dusty plasma medium: Fluid and particle approach". Journal of Plasma Physics 80, nr 6 (14.07.2014): 817–23. http://dx.doi.org/10.1017/s0022377814000397.
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The Kelvin-Helmholtz (KH) instability is studied in a two dimensional strongly coupled dusty plasma medium using a fluid approach as well as through a molecular dynamic (MD) simulation. For the fluid description the generalized hydrodynamic (GH) model which treats the strongly coupled dusty plasma as a visco-elastic fluid is adopted. For the MD studies the ensemble of particles are assumed to interact through a Yukawa potential. Both the approaches predict a stabilization of the KH growth rate with an increase in the strong coupling parameter. The present study also delineates the temporal evolution and the interaction of transverse shear waves with the collective dynamics of the dusty plasma medium within the framework of both these approaches.
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Haq, Mazhar Ul, Zhao Gang, Zhuang Zhi Sun i S. M. Aftab. "Force Analysis of IPMC Actuated Fin and Wing Assembly of a Micro Scanning Device through Two-Way Fluid Structure Interaction Approach". International Journal of Engineering Research in Africa 21 (grudzień 2015): 19–32. http://dx.doi.org/10.4028/www.scientific.net/jera.21.19.
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In this paper, a methodology is presented to perform force analysis of wing and fin assembly of a micro fish like device through strongly coupled two-way fluid structure interaction approach. The scanning device operates underwater and is towed by a surface vessel through a tow cable. Device fins are actuated by ionic polymer metal composite (IPMC) actuators, an EAP actuator. Fins act as riser, depressor and stabiliser against roll motion of the device. During tow, wing and fin assembly of the device come under hydrodynamic forces. These forces are influenced by fin displacement under IPMC actuation and wing's angle of attack for same towing conditions. To fully investigate wing and fin assembly performance, we must consider the interaction between their structure and fluid (water) and model the coupling mechanism accurately for fluid structure interaction (FSI) analysis. To obtain an accurate prediction to the hydrodynamic forces on wing and fin assembly of the device, it is necessary to conduct dynamic analysis of the surrounding fluid by computational fluid dynamics (CFD). A numerical simulation of three dimensional model of the assembly is performed in ANSYS WORKBENCH by coupling transient structural and Fluid Flow (CFX) analysis systems. The objectives of this study are as follows: 1) To build an accurate three-dimensional CFD model of the wing and IPMC actuated fin 2) To quantify the lift and drag forces acting on the wing and their corresponding coefficients 3) To demonstrate the influence of wing's angle of attack and fin displacement on generation of lift and drag forces. The presented methodology is also applicable to self-propelled micro robots.
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Alharbi, A., I. Ballai, V. Fedun i G. Verth. "Slow magnetoacoustic waves in gravitationally stratified two-fluid plasmas in strongly ionized limit". Monthly Notices of the Royal Astronomical Society 501, nr 2 (12.12.2020): 1940–50. http://dx.doi.org/10.1093/mnras/staa3835.
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ABSTRACT The plasma dynamics at frequencies comparable with collisional frequency between various species has to be described in multifluid framework, where collisional interaction between particles is an important ingredient. In our study, we will assume that charged particles are strongly coupled, meaning that they form a single fluid that interacts with neutrals, therefore we will employ a two-fluid model. Here, we aim to investigate the evolutionary equation of slow sausage waves propagating in a gravitationally stratified flux tube in the two-fluid solar atmosphere in a strongly ionized limit using an initial value analysis. Due to the collisional interaction between massive particles (ions and neutrals), the governing equations are coupled. Solutions are sought in the strongly ionized limit and the density ratio between neutrals and charged particles is a small parameter. This limit is relevant to the upper part of the chromosphere. Our results show that slow sausage waves associated with charged particles propagate such that their possible frequency is affected by a cut-off due to the gravitational stratification. In contrast, for neutral acoustic waves the cut-off value applies on their wavelength and only small wavelength waves are able to propagate. Slow modes associated with neutrals are driven by the collisional coupling with ions.
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Collis, J., D. L. Brown, M. E. Hubbard i R. D. O’Dea. "Effective equations governing an active poroelastic medium". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 473, nr 2198 (luty 2017): 20160755. http://dx.doi.org/10.1098/rspa.2016.0755.
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In this work, we consider the spatial homogenization of a coupled transport and fluid–structure interaction model, to the end of deriving a system of effective equations describing the flow, elastic deformation and transport in an active poroelastic medium. The ‘active’ nature of the material results from a morphoelastic response to a chemical stimulant, in which the growth time scale is strongly separated from other elastic time scales. The resulting effective model is broadly relevant to the study of biological tissue growth, geophysical flows (e.g. swelling in coals and clays) and a wide range of industrial applications (e.g. absorbant hygiene products). The key contribution of this work is the derivation of a system of homogenized partial differential equations describing macroscale growth, coupled to transport of solute, that explicitly incorporates details of the structure and dynamics of the microscopic system, and, moreover, admits finite growth and deformation at the pore scale. The resulting macroscale model comprises a Biot-type system, augmented with additional terms pertaining to growth, coupled to an advection–reaction–diffusion equation. The resultant system of effective equations is then compared with other recent models under a selection of appropriate simplifying asymptotic limits.
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MUKHERJEE, SWARNAVA, SHANMUKH SARODE, CHINMAYEE MUJUMDAR, LIZHI SHANG i ANDREA VACCA. "EFFECT OF DYNAMIC COUPLING ON THE PERFORMANCE OF PISTON PUMP LUBRICATING INTERFACES". MM Science Journal 2022, nr 3 (27.09.2022): 5783–90. http://dx.doi.org/10.17973/mmsj.2022_10_2022075.
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The energy efficiency and durability performance of axial piston machines are strongly affected by the tribological behavior of their lubricating interfaces. State-of-the-art approaches typically study these interface in isolation, neglecting possible reciprocal interactions between such interfaces. This paper presents an investigation of the mutual interaction between the piston/cylinder interface and the slipper/swashplate interface of a commercial axial piston pump. The proposed model can predict distributive fluid behavior in the lubricating gaps considering the effects of dynamics of the solid bodies, compressibility, mixed lubrication, elastic deformation, and cavitation. The dynamic coupling between the piston and the slipper is achieved by modeling the friction between the piston ball and slipper socket based on the force balance and the relative motion between the two bodies. The efficiencies predicted by this coupled model are compared to the ones obtained through the more established approach of solving the lubricating interfaces independently. The simulation results demonstrate the influence of the coupled physics on the lubricating interface performance, confirming the necessity of considering couple dynamics in lubricating interface numerical modeling.
Rozprawy doktorskie na temat "Strongly coupled fluid-structure interaction model"
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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.
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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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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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König, Marcel [Verfasser], i Alexander [Akademischer Betreuer] Düster. "Partitioned solution strategies for strongly-coupled fluid-structure interaction problems in maritime applications / Marcel König ; Betreuer: Alexander Düster". Hamburg : Universitätsbibliothek der Technischen Universität Hamburg-Harburg, 2018. http://d-nb.info/1165650630/34.
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(9746363), Thomas Ransegnola. "A Strongly Coupled Simulation Model of Positive Displacement Machines for Design and Optimization". Thesis, 2020.
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Positive displacement machines are used in a wide variety of applications, ranging from fluid power where they act as a transmission of power, to lubrication and fluid transport. As the core of the fluid system responsible for mechanical--hydraulic energy conversion, the efficiencies of these units are a major driver of the total efficiency of the system. Furthermore, the durability of these units is a strong decider in the useful life of the system in which they operate.
The key challenge in designing these units comes from understanding their working principles and designing their lubricating interfaces, which must simultaneously perform a load carrying and sealing function as the unit operates. While most of the physical phenomena relevant to these machines have been studied previously in some capacity, the significance of their mutual interactions has not. For this reason, the importance of these mutual interactions is a fundamental question in these machines that this thesis answers for the first time. In analysis of two different machine types, it is confirmed that mutual interactions of both physical phenomena and neighboring fluid domains of the unit contribute significantly to the overall performance of the machine. Namely, these analyses demonstrate load sharing owing to mutual interactions on average of 20% and as high as 50%, and mutual flow interactions of at least 10%.
In this thesis, the behavior of the thin films of fluid in the lubricating interfaces of the units, the bodies that make up these films, and the volumes which interface with them will be considered. The resulting coupled problem requires a model that can consider the effects of motion of all floating bodies on all films and volumes, and collect the resulting loads applied by the fluid as it responds. This will require a novel 6 degree of freedom dynamics model including the inertia of the bodies and the transient pressure and shear loads of all interfaces of the body and the fluid domain.
During operation, fluid cavitation and aeration can occur in both the displacement chambers of the machine and its lubricating interfaces. To capture this, a novel cavitation algorithm is developed in this thesis, which considers the release of bubbles due to both gas trapped within the fluid and vaporization of the operating fluid in localized low pressure regions of the films. In the absence of cavitation, this model will also be used to find the pressures and flows over the film, communicating this information with the remainder of the fluid domain.
Due to the high pressures that form in these units, the bodies deform. The resulting deformation changes the shape of the films and therefore its pressure distribution. This coupled effect will be captured in one of two ways, the first relying on existing geometric information of the unit, and the other using a novel analytical approach that is developed to avoid this necessity. In either case, the added damping due to the shear of the materials will be considered for the first time. Additionally in regions of low gap height, mixed lubrication occurs and the effects of the surface asperities of the floating bodies cannot be neglected. Accurate modeling of this condition is necessary to predict wear that leads to failure in these units. This work will then develop a novel implementation for mixed lubrication modeling that is directly integrated into the cavitation modeling approach.
Finally, effort is made to maintain a generic tools, such that the model can be applied to any positive displacement machine. This thesis will present the first toolbox of its kind, which accounts for all the mentioned aspects in such a way that they can be captured for any machine. Using both multithreaded and sequential implementations, the tool will be capable of fully utilizing a machine on which it is run for both low latency (design) and high throughput (optimization) applications respectively. In order to make these applications feasible, the various modules of the tool will be strongly coupled using asynchronous time stepping. This approach is made possible with the development of a novel impedance tensor of the mixed universal Reynolds equation, and shows marked improvements in simulation time by requiring at most 50% of the simulation time of existing approaches.
In the present thesis, the developed tool will be validated using experimental data collected from 3 fundamentally different machines. Individual advancements of the tool will also be verified in isolation with comparison to the state of the art and commercial software in the relevant fields. As a demonstration of the use of the tool for design, detailed analysis of the displacing actions and lubricating interfaces of these same units will be performed. These validations demonstrate the ability of the tool to predict machine efficiencies with error averaging around 1% over all operating conditions for multiple machine types, and capture transient behavior of the units. To demonstrate the utility as a virtual optimization tool, design of a complete external gear machine design will be performed. This demonstration will start from only analytical parameters, and will track a route to a complete prototype.
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Habbal, Feras. "The Optimal Transportation Meshfree Method for General Fluid Flows and Strongly Coupled Fluid-Structure Interaction Problems". Thesis, 2009. https://thesis.library.caltech.edu/5220/2/FH_cit_thesis_FH_2.pdf.
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This thesis develops a novel meshfree numerical method for simulating general fluid flows. Drawing from concepts in optimal mass transport theory and in combination with the notion of material point sampling and meshfree interpolation, the optimal transport meshfree (OTM) method provides a rigorous mathematical framework for numerically simulating three-dimensional general fluid flows with general, and possibly moving boundaries (as in fluid-structure interaction simulations). Specifically, the proposed OTM method generalizes the Benamou-Brenier differential formulation of optimal mass transportation problems which leads to a multi-field variational characterization of general fluid flows including viscosity, equations of state and general geometries and boundary conditions. With the use of material point sampling in conjunction with local max-entropy shape functions, the OTM method leads to a meshfree formulation bearing a number of salient features. Compared with other meshfree methods that face significant challenges to enforce essential boundary conditions as well as couple to other methods, such as the finite element method, the OTM method provides a new paradigm in meshfree methods. The OTM method is numerically validated by simulating the classical Riemann benchmark example for Euler flow. Furthermore, in order to highlight the ability of the OTM to simulate Navier-Stokes flows within general, moving three-dimensional domains, and naturally couple with finite elements, an illustrative strongly coupled FSI example is simulated. This illustrative FSI example, consisting of a gas-inflated sphere impacting the ground, is simulated as a toy model of the final phase of NASA's landing scheme devised for Mars missions, where a network of airbags are deployed to dissipate the energy of impact.
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Buczkowski, Daniel. "Coupled fluid-structure interaction numerical model of the shock absorber valve". Rozprawa doktorska, 2021. https://repolis.bg.polsl.pl/dlibra/docmetadata?showContent=true&id=72843.
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Buczkowski, Daniel. "Coupled fluid-structure interaction numerical model of the shock absorber valve". Rozprawa doktorska, 2021. https://delibra.bg.polsl.pl/dlibra/docmetadata?showContent=true&id=72843.
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Nitti, Alessandro. "Development of a multiphysics solver for complex coupled problems involving thin shells: fluid-structure-electrophysiology interaction". Doctoral thesis, 2021. http://hdl.handle.net/11589/213838.
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The present work is devoted to the development of a multiphysics solver for simulating two
classes of coupled problems.
A computational framework is designed to accurately predict the elastic response of thin shells
undergoing large displacements induced by local hydrodynamic forces, as well as to resolve the
complex fluid pattern arising from its interaction with an incompressible fluid. Within the context
of partitioned algorithms, two different approaches are employed for the fluid and structural
domain. The fluid motion is resolved with a pressure projection method on a Cartesian structured
grid. The immersed shell is modeled by means of a NURBS surface, and the elastic response is
obtained from a displacement-based Isogeometric Analysis relying on the Kirchhoff-Love theory.
The two solvers exchange data through a direct-forcing Immersed Boundary approach, where the
interpolation/spreading of the variables between Lagrangian and Eulerian grids is implemented
with a Moving Least Squares approximation, which has proven to be very eective for moving
boundaries. In this scenario, the isoparametric paradigm is exploited to perform an adaptive collocation
of the Lagrangian markers, decoupling the local grid density of fluid and shell domains
and reducing the computational expense. The convergence rate of the method is verified by refinement
analyses, segregating the Eulerian/Lagrangian refinement, which confirms the expected
scheme accuracy in space and time. The effectiveness of the method is then verified against
different test–cases of engineering and biologic inspiration, involving fundamentally different
physical and numerical conditions, namely: i) a flapping flag, ii) an inverted flag, iii) a clamped
plate, iv) a buoyant seaweed in a free stream. Both strong and loose coupling approaches are
implemented to handle different fluid-to-structure density ratios, providing accurate results.
In second instance, we propose an IGA approximation of the system of equations describing
the propagation of an electrophysiologic stimulus over a thin cardiac tissue with the subsequent
muscle contraction. The underlying method relies on the monodomain model for the electrical
sub-problem. This requires the solution of a reaction-diffusion equation over a surface in
the three-dimensional space. Exploiting the benefits of the high-order NURBS basis functions
within a curvilinear framework, the method is found to reproduce complex excitation patterns
with a limited number of degrees of freedom. Furthermore, the curvilinear description of the
diusion term provides a flexible and easy-to-implement approach for general surfaces.
The electrophysiological stimulus is converted into a mechanical load by means of the wellestablished
active strain approach. The multiplicative decomposition of the deformation gradient
tensor is grafted into the classical finite elasticity weak formulation, providing the necessary tensor
expressions in curvilinear coordinates. The expressions derived provides what is needed to
implement the active strain approach in standard finite-element solvers without resorting to dedicated
formulations. Such a formulation is valid for general three-dimensional geometries and
isotropic hyperelastic materials. The formulation is then restricted to Kirchhoff-Love shells by means of the static condensation of the material tensor. The purely elastic response of the structure
is investigated with simple static test-cases of thin shells undergoing different active strain
patterns. Eventually, various numerical tests performed with a staggered scheme illustrate that
the coupled electromechanical model can capture the excitation-contraction mechanism over thin
tissue and reproduce complex curvature variations.
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I-ChenTsai i 蔡宜真. "Numerical Simulation of 2-D Fluid-Structure Interaction with Tightly Coupled Solver and Establishment of the Mooring Model". Thesis, 2019. http://ndltd.ncl.edu.tw/handle/dc3kuh.
Pełny tekst źródłaKsiążki na temat "Strongly coupled fluid-structure interaction model"
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Wang, Bin. Intraseasonal Modulation of the Indian Summer Monsoon. Oxford University Press, 2018. http://dx.doi.org/10.1093/acrefore/9780190228620.013.616.
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The strongest Indian summer monsoon (ISM) on the planet features prolonged clustered spells of wet and dry conditions often lasting for two to three weeks, known as active and break monsoons. The active and break monsoons are attributed to a quasi-periodic intraseasonal oscillation (ISO), which is an extremely important form of the ISM variability bridging weather and climate variation. The ISO over India is part of the ISO in global tropics. The latter is one of the most important meteorological phenomena discovered during the 20th century (Madden & Julian, 1971, 1972). The extreme dry and wet events are regulated by the boreal summer ISO (BSISO). The BSISO over Indian monsoon region consists of northward propagating 30–60 day and westward propagating 10–20 day modes. The “clustering” of synoptic activity was separately modulated by both the 30–60 day and 10–20 day BSISO modes in approximately equal amounts. The clustering is particularly strong when the enhancement effect from both modes acts in concert. The northward propagation of BSISO is primarily originated from the easterly vertical shear (increasing easterly winds with height) of the monsoon flows, which by interacting with the BSISO convective system can generate boundary layer convergence to the north of the convective system that promotes its northward movement. The BSISO-ocean interaction through wind-evaporation feedback and cloud-radiation feedback can also contribute to the northward propagation of BSISO from the equator. The 10–20 day oscillation is primarily produced by convectively coupled Rossby waves modified by the monsoon mean flows. Using coupled general circulation models (GCMs) for ISO prediction is an important advance in subseasonal forecasts. The major modes of ISO over Indian monsoon region are potentially predictable up to 40–45 days as estimated by multiple GCM ensemble hindcast experiments. The current dynamical models’ prediction skills for the large initial amplitude cases are approximately 20–25 days, but the prediction of developing BSISO disturbance is much more difficult than the prediction of the mature BSISO disturbances. This article provides a synthesis of our current knowledge on the observed spatial and temporal structure of the ISO over India and the important physical processes through which the BSISO regulates the ISM active-break cycles and severe weather events. Our present capability and shortcomings in simulating and predicting the monsoon ISO and outstanding issues are also discussed.
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Goswami, B. N., i Soumi Chakravorty. Dynamics of the Indian Summer Monsoon Climate. Oxford University Press, 2017. http://dx.doi.org/10.1093/acrefore/9780190228620.013.613.
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Lifeline for about one-sixth of the world’s population in the subcontinent, the Indian summer monsoon (ISM) is an integral part of the annual cycle of the winds (reversal of winds with seasons), coupled with a strong annual cycle of precipitation (wet summer and dry winter). For over a century, high socioeconomic impacts of ISM rainfall (ISMR) in the region have driven scientists to attempt to predict the year-to-year variations of ISM rainfall. A remarkably stable phenomenon, making its appearance every year without fail, the ISM climate exhibits a rather small year-to-year variation (the standard deviation of the seasonal mean being 10% of the long-term mean), but it has proven to be an extremely challenging system to predict. Even the most skillful, sophisticated models are barely useful with skill significantly below the potential limit on predictability. Understanding what drives the mean ISM climate and its variability on different timescales is, therefore, critical to advancing skills in predicting the monsoon. A conceptual ISM model helps explain what maintains not only the mean ISM but also its variability on interannual and longer timescales.The annual ISM precipitation cycle can be described as a manifestation of the seasonal migration of the intertropical convergence zone (ITCZ) or the zonally oriented cloud (rain) band characterized by a sudden “onset.” The other important feature of ISM is the deep overturning meridional (regional Hadley circulation) that is associated with it, driven primarily by the latent heat release associated with the ISM (ITCZ) precipitation. The dynamics of the monsoon climate, therefore, is an extension of the dynamics of the ITCZ. The classical land–sea surface temperature gradient model of ISM may explain the seasonal reversal of the surface winds, but it fails to explain the onset and the deep vertical structure of the ISM circulation. While the surface temperature over land cools after the onset, reversing the north–south surface temperature gradient and making it inadequate to sustain the monsoon after onset, it is the tropospheric temperature gradient that becomes positive at the time of onset and remains strongly positive thereafter, maintaining the monsoon. The change in sign of the tropospheric temperature (TT) gradient is dynamically responsible for a symmetric instability, leading to the onset and subsequent northward progression of the ITCZ. The unified ISM model in terms of the TT gradient provides a platform to understand the drivers of ISM variability by identifying processes that affect TT in the north and the south and influence the gradient.The predictability of the seasonal mean ISM is limited by interactions of the annual cycle and higher frequency monsoon variability within the season. The monsoon intraseasonal oscillation (MISO) has a seminal role in influencing the seasonal mean and its interannual variability. While ISM climate on long timescales (e.g., multimillennium) largely follows the solar forcing, on shorter timescales the ISM variability is governed by the internal dynamics arising from ocean–atmosphere–land interactions, regional as well as remote, together with teleconnections with other climate modes. Also important is the role of anthropogenic forcing, such as the greenhouse gases and aerosols versus the natural multidecadal variability in the context of the recent six-decade long decreasing trend of ISM rainfall.
Części książek na temat "Strongly coupled fluid-structure interaction model"
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Franci, Alessandro. "Industrial Application: PFEM Analysis Model of NPP Severe Accident". W Unified Lagrangian Formulation for Fluid and Solid Mechanics, Fluid-Structure Interaction and Coupled Thermal Problems Using the PFEM, 187–206. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-45662-1_6.
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Martin, Katharina, Dennis Daub, Burkard Esser, Ali Gülhan i Stefanie Reese. "Numerical Modelling of Fluid-Structure Interaction for Thermal Buckling in Hypersonic Flow". W Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 341–55. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-53847-7_22.
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Abstract Experiments have shown that a high-enthalpy flow field might lead under certain mechanical constraints to buckling effects and plastic deformation. The panel buckling into the flow changes the flow field causing locally increased heating which in turn affects the panel deformation. The temperature increase due to aerothermal heating in the hypersonic flow causes the metallic panel to buckle into the flow. To investigate these phenomena numerically, a thermomechanical simulation of a fluid-structure interaction (FSI) model for thermal buckling is presented. The FSI simulation is set up in a staggered scheme and split into a thermal solid, a mechanical solid and a fluid computation. The structural solver Abaqus and the fluid solver TAU from the German Aerospace Center (DLR) are coupled within the FSI code ifls developed at the Institute of Aircraft Design and Lightweight Structures (IFL) at TU Braunschweig. The FSI setup focuses on the choice of an equilibrium iteration method, the time integration and the data transfer between grids. To model the complex material behaviour of the structure, a viscoplastic material model with linear isotropic hardening and thermal expansion including material parameters, which are nonlinearly dependent on temperature, is used.
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Semba, Kouichi. "Emerging Ultrastrong Coupling Between Light and Matter Observed in Circuit Quantum Electrodynamics". W International Symposium on Mathematics, Quantum Theory, and Cryptography, 7–8. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-5191-8_3.
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Abstract The strength of the coupling between an atom and a single electromagnetic field mode is defined as the ratio of the vacuum Rabi frequency to the Larmor frequency, and is determined by a small dimensionless physical constant, the fine structure constant $$\alpha =Z_{vac} / 2R_{K}$$. On the other hand, the quantum circuit including Josephson junctions behaving as artificial atoms and it can be coupled to the electromagnetic field with arbitrary strength (Devoret et al. 2007). Therefore, the circuit quantum electrodynamics (circuit QED) is extremely suitable for studying much stronger light-matter interaction.
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Topinka, Lukáš, Radomír Pruša, Rostislav Huzlík i Joachim Regel. "Definition of a Non-contact Induction Heating of a Cutting Tool as a Substitute for the Process Heat for the Verification of a Thermal Simulation Model". W Lecture Notes in Production Engineering, 333–44. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-34486-2_24.
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AbstractDuring metal machining, a large amount of heat is generated in the cutting zone, which has a negative impact on machining accuracy due to the thermal expansion of the materials. To reduce the temperature in the cutting zone, liquid coolants are used which increase the costs and can have a negative impact on the environment. This problem is being studied using Computational Fluid Dynamics (CFD) to better understand the behavior of the coolant flow in the cutting zone, which will allow optimization of the use of liquid coolants and the development of a correction method for thermal errors, resulting in more accurate machining with reduced resource and environmental footprints. However, due to the complexity of multiphase CFD simulations, the simulation model must be simplified as much as possible. This is particularly important for the process heat generation, as combining flow simulation of coolant flow around the rotating cutting tool with structural simulation of the milling process, including chip formation, would require excessive computational power. In following paper an alternative method of tool heating by electromagnetic induction is presented and the measurement dependencies required to determine the heat flux induced into the cutting tool are described. This can be further applied as a boundary condition for the numerical simulation as a verification method for the coupled Fluid-Structure Interaction FSI simulation model of the thermally induced deformations of the cutting tool and its holder.
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Hosseinzadeh, Saeed, i Kristjan Tabri. "Numerical Investigation of Hydroelastic Response of a Three-Dimensional Deformable Hydrofoil". W Progress in Marine Science and Technology. IOS Press, 2020. http://dx.doi.org/10.3233/pmst200029.
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The present study is concerned with the numerical simulation of Fluid-Structure Interaction (FSI) on a deformable three-dimensional hydrofoil in a turbulent flow. The aim of this work is to develop a strongly coupled two-way fluid-structure interaction methodology with a sufficiently high spatial accuracy to examine the effect of turbulent and cavitating flow on the hydroelastic response of a flexible hydrofoil. A 3-D cantilevered hydrofoil with two degrees-of-freedom is considered to simulate the plunging and pitching motion at the foil tip due to bending and twisting deformation. The defined problem is numerically investigated by coupled Finite Volume Method (FVM) and Finite Element Method (FEM) under a two-way coupling method. In order to find a better understanding of the dynamic FSI response and stability of flexible lifting bodies, the fluid flow is modeled in the different turbulence models and cavitation conditions. The flow-induced deformation and elastic response of both rigid and flexible hydrofoils at various angles of attack are studied. The effect of three-dimension body, pressure coefficient at different locations of the hydrofoil, leading-edge and trailing-edge deformation are presented and the results show that because of elastic deformation, the angle of attack increases and it lead to higher lift and drag coefficients. In addition, the deformations are generally limited by stall condition and because of unsteady vortex shedding, the post-stall condition should be considered in FSI simulation of deformable hydrofoil. To evaluate the accuracy of the numerical model, the present results are compared and validated against published experimental data and showed good agreement.
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König, Marcel. "4 Coupled Problems". W Partitioned Solution Strategies for Strongly-Coupled Fluid-Structure Interaction Problems in Maritime Applications, 42–97. VDI Verlag, 2018. http://dx.doi.org/10.51202/9783186351180-42.
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König, Marcel. "2 Fluid Problems". W Partitioned Solution Strategies for Strongly-Coupled Fluid-Structure Interaction Problems in Maritime Applications, 5–24. VDI Verlag, 2018. http://dx.doi.org/10.51202/9783186351180-5.
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König, Marcel. "1 Introduction". W Partitioned Solution Strategies for Strongly-Coupled Fluid-Structure Interaction Problems in Maritime Applications, 1–4. VDI Verlag, 2018. http://dx.doi.org/10.51202/9783186351180-1.
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König, Marcel. "6 Benchmark Problems". W Partitioned Solution Strategies for Strongly-Coupled Fluid-Structure Interaction Problems in Maritime Applications, 158–217. VDI Verlag, 2018. http://dx.doi.org/10.51202/9783186351180-158.
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König, Marcel. "7 Advanced Applications". W Partitioned Solution Strategies for Strongly-Coupled Fluid-Structure Interaction Problems in Maritime Applications, 218–40. VDI Verlag, 2018. http://dx.doi.org/10.51202/9783186351180-218.
Pełny tekst źródłaStreszczenia konferencji na temat "Strongly coupled fluid-structure interaction model"
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Lombardi, Matteo, Massimiliano Cremonesi, Andrea Giampieri, Nicola Parolini i Alfio Quarteroni. "A Strongly Coupled Fluid-Structure Interaction Model for Wind-Sail Simulation". W High Performance Yacht Design. RINA, 2012. http://dx.doi.org/10.3940/rina.hpyd.2012.24.
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Gangadharan, Manoj Kumar, i Sriram Venkatachalam. "A Hybrid Numerical Model to Address Fluid Elastic Structure Interaction". W ASME 2016 35th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/omae2016-54161.
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Hydroelasticity is an important problem in the field of ocean engineering. It can be noted from most of the works published as well as theories proposed earlier that this particular problem was addressed based on the time independent/ frequency domain approach. In this paper, we propose a novel numerical method to address the fluid-structure interaction problem in time domain simulations. The hybrid numerical model proposed earlier for hydro-elasticity (Sriram and Ma, 2012) as well as for breaking waves (Sriram et al 2014) has been extended to study the problem of breaking wave-elastic structure interaction. The method involves strong coupling of Fully Nonlinear Potential Flow Theory (FNPT) and Navier Stokes (NS) equation using a moving overlapping zone in space and Runge kutta 2nd order with a predictor corrector scheme in time. The fluid structure interaction is achieved by a near strongly coupled partitioned procedure. The simulation was performed using Finite Element method (FEM) in the FNPT domain, Particle based method (Improved Meshless Local Petrov Galerkin based on Rankine source, IMPLG_R) in the NS domain and FEM for the structural dynamics part. The advantage of using this approach is due to high computational efficiency. The method has been applied to study the interaction between breaking waves and elastic wall.
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Gaul, Lothar. "Acoustic Fluid-Structure Interaction". W ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-63601.
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The vibration behavior of ships is noticeably influenced by the surrounding water, which represents a fluid of high density. In this case, the feedback of the fluid pressure onto the structure cannot be neglected and a strong coupling scheme between the fluid domain and the structural domain is necessary. In this work, fast boundary element methods are used to model the semi-infinite fluid domain with the free water surface. Two approaches are compared: A symmetric mixed formulation is applied where a part of the water surface is discretized. The second approach is a formulation with a special half-space fundamental solution, which allows the exact representation of the Dirichlet boundary condition on the free water surface without its discretization. Furthermore, the influence of the compressibility of the water is investigated by comparing the solutions of the Helmholtz and the Laplace equation. The ship itself is modeled with the finite element method. A binary interface to the commercial finite element package ANSYS is used to import the mass matrix and the stiffness matrix. The coupled problems are formulated using Schur complements. To solve the resulting system of equations, a combination of a direct solver for the finite element matrix and a preconditioned GMRES for the overall Schur complement is chosen. The applicability of the approach is demonstrated using a realistic model problem.
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Ebna Hai, Bhuiyan Shameem Mahmood, Markus Bause i Paul Kuberry. "Finite Element Approximation of the Extended Fluid-Structure Interaction (eXFSI) Problem". W ASME 2016 Fluids Engineering Division Summer Meeting collocated with the ASME 2016 Heat Transfer Summer Conference and the ASME 2016 14th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/fedsm2016-7506.
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This contribution is the second part of three papers on Adaptive Multigrid Methods for the eXtended Fluid-Structure Interaction (eXFSI) Problem, where we introduce a monolithic variational formulation and solution techniques. To the best of our knowledge, such a model is new in the literature. This model is used to design an on-line structural health monitoring (SHM) system in order to determine the coupled acoustic and elastic wave propagation in moving domains and optimum locations for SHM sensors. In a monolithic nonlinear fluid-structure interaction (FSI), the fluid and structure models are formulated in different coordinate systems. This makes the FSI setup of a common variational description difficult and challenging. This article presents the state-of-the-art in the finite element approximation of FSI problem based on monolithic variational formulation in the well-established arbitrary Lagrangian Eulerian (ALE) framework. This research focuses on the newly developed mathematical model of a new FSI problem, which is referred to as extended Fluid-Structure Interaction (eXFSI) problem in the ALE framework. The eXFSI is a strongly coupled problem of typical FSI with a coupled wave propagation problem on the fluid-solid interface (WpFSI). The WpFSI is a strongly coupled problem of acoustic and elastic wave equations, where wave propagation problems automatically adopts the boundary conditions from the FSI problem at each time step. The ALE approach provides a simple but powerful procedure to couple solid deformations with fluid flows by a monolithic solution algorithm. In such a setting, the fluid problems are transformed to a fixed reference configuration by the ALE mapping. The goal of this work is the development of concepts for the efficient numerical solution of eXFSI problem, the analysis of various fluid-solid mesh motion techniques and comparison of different second-order time-stepping schemes. This work consists of the investigation of different time stepping scheme formulations for a nonlinear FSI problem coupling the acoustic/elastic wave propagation on the fluid-structure interface. Temporal discretization is based on finite differences and is formulated as a one step-θ scheme, from which we can consider the following particular cases: the implicit Euler, Crank-Nicolson, shifted Crank-Nicolson and the Fractional-Step-θ schemes. The nonlinear problem is solved with a Newton-like method where the discretization is done with a Galerkin finite element scheme. The implementation is accomplished via the software library package DOpElib based on the deal.II finite element library for the computation of different eXFSI configurations.
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Katagiri, Kengo, Absei Krdey, Sota Yamamoto i Marie Oshima. "Strong Coupled Fluid-Structure Interaction Simulation of Cerebrovascular System Using Multi-Scale Model". W ASME 2012 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/sbc2012-80415.
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Cerebrovascular disorder such as subarachnoid hemorrhage is the number 3 cause of death in Japan [1]. Initiation and growth of those diseases depend on hemodynamic factors such as Wall Shear Stress (WSS) or blood pressure induced by blood flow [2]. Therefore the information on the magnitude and the distribution of WSS is important to predict the consequences.
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Barabas, Botond, Friedrich-Karl Benra, Nico Petry i Dieter Brillert. "Experimental Damping Behavior of Strongly Coupled Structure and Acoustic Modes of a Rotating Disk With Side Cavities". W ASME Turbo Expo 2021: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/gt2021-58782.
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Abstract High cycle fatigue is a continuous research topic within the turbomachine community. One field of the investigations is the fluid-structure interaction of 2-D impellers, which can be simplified as disks with their surrounding side cavities. In modern machines the pressure ratios tend to increase along with pressure fluctuations and the excitation potential on the impellers. The vibrational interactions between side cavities, filled with high pressure fluid, and the disk structure play an important role in machine design. However, they are not fully understood, yet. Vibrations at frequencies that have been uncritical at lower pressure levels could become critical at higher pressure levels. Additionally, coupling effects between fluid and structure are becoming stronger at higher fluid densities. For a safe and reliable design, the excitation and the damping mechanism of coupled modes has to be better understood. This paper summarizes the test rig setup and focuses on one of the main findings of an extensive experimental research project, which investigated the fluid-structure interaction of a disk with side cavities, at the University of Duisburg-Essen. The focus lays on the damping behavior of strongly coupled acoustic and structure modes. Measurement results gathered at the aeroacoustic test rig are presented. The results show the influence of fluid pressure variations on the damping behavior of acoustic modes. Therefore, the response functions of some selected acoustic modes are evaluated with the half-width method. Compared to the weakly coupled structure mode, the damping of the strongly coupled structure mode is some orders higher at atmospheric pressure conditions. The damping ratio decreases with an increasing pressure level, however still remains some orders higher, than the damping of weakly coupled structure modes.
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Seeley, Charles E., Stan Weaver i Brian Rush. "Fluid-Structure Interaction Model of a Synthetic Jet Using Coupled Computational Fluid Dynamics and Finite Elements". W ASME 2012 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/smasis2012-8197.
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Synthetic jets offer new capabilities for localized active cooling of electronics due to their compact size, low cost and substantial cooling effectiveness. The design of devices to create synthetic jets and optimize active cooling performance is challenging due to the strong, two way, fluid-structure interaction (FSI) between the working fluid and the flexible structure that moves the fluid driven with piezoelectric actuators. Previous modeling efforts relied on lumped parameter approaches or electrical analogs. Although computationally less intensive, these approaches may not be accurate in all regions of the design space of interest and trade off fidelity for ease of use. In this effort, a 3D finite element model of the structure is coupled with a 3D computational fluid dynamics model of the fluid to explore the viability of such an approach. The motion of the structure moves the fluid grid, and the fluid feeds back pressure forces onto the structure that are required to converge at each iteration. Transient response of the deflection, pressure and exit velocity will be presented. Validation of the FSI model with experimental data for the frequency response of these quantities will also be presented.
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Gomes, Jorge Pereira, i Hermann Lienhart. "Fluid-Structure Interaction Exciting Mechanisms of Flexible Structures in Uniform Flows". W ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting collocated with 8th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2010. http://dx.doi.org/10.1115/fedsm-icnmm2010-30948.
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The oscillation of a structure immersed on a flow can become self-excited as a result of different fluid-structure interaction mechanisms. To identify the self-exciting mechanisms and to understand the influence of the physical parameters on the different exciting processes, the two-dimensional free swivelling movement of flexible structure models were investigated in both laminar and turbulent uniform flows. The coupled fluid and structure movement was characterized using a particle image velocimetry (PIV) system complemented by a time-phase detector to obtain accurate time-phase resolved measurements of the flow velocity field and structure deformation. The experimental tests proved that the self-exciting mechanisms are strongly dependent on the approaching flow velocity. For the velocity range tested, a sequence of clearly defined movement-induced excitation (MIE) and instability-induced excitation (IIE) of the model was observed on increasing the velocity of the incoming flow. In this contribution, the results for one specific structure configuration are presented.
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Pantano-Rubino, Carlos, Kostas Karagiozis, Ramji Kamakoti i Fehmi Cirak. "Computational Fluid-Structure Interaction of DGB Parachutes in Compressible Fluid Flow". W ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting collocated with 8th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2010. http://dx.doi.org/10.1115/fedsm-icnmm2010-30898.
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This paper describes large-scale simulations of compressible flows over a supersonic disk-gap-band parachute system. An adaptive mesh refinement method is used to resolve the coupled fluid-structure model. The fluid model employs large-eddy simulation to describe the turbulent wakes appearing upstream and downstream of the parachute canopy and the structural model employed a thin-shell finite element solver that allows large canopy deformations by using subdivision finite elements. The fluid-structure interaction is described by a variant of the Ghost-Fluid method. The simulation was carried out at Mach number 1.96 where strong nonlinear coupling between the system of bow shocks, turbulent wake and canopy is observed. It was found that the canopy oscillations were characterized by a breathing type motion due to the strong interaction of the turbulent wake and bow shock upstream of the flexible canopy.
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Kallinderis, Yannis, i Hyung Taek Ahn. "Strongly Coupled Fluid-Structure Interactions via a New Navier-Stokes Method for Prediction of Vortex-Induced Vibrations". W ASME 2005 24th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2005. http://dx.doi.org/10.1115/omae2005-67352.
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Numerical prediction of vortex-induced vibrations requires employment of the unsteady Navier-Stokes equations. Current Navier-Stokes solvers are quite expensive for three-dimensional flow-structure applications. Acceptance of Computational Fluid Dynamics as a design tool for the offshore industry requires improvements to current CFD methods in order to address the following important issues: (i) stability and computation cost of the numerical simulation process, (ii) restriction on the size of the allowable time-step due to the coupling of the flow and structure solution processes, (iii) excessive number of computational elements for 3-D applications, and (iv) accuracy and computational cost of turbulence models used for high Reynolds number flow. The above four problems are addressed via a new numerical method which employs strong coupling between the flow and the structure solutions. Special coupling is also employed between the Reynolds-averaged Navier-Stokes equations and the Spalart-Allmaras turbulence model. An element-type independent spatial discretization scheme is also presented which can handle general hybrid meshes consisting of hexahedra, prisms, pyramids, and tetrahedral.