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Artykuły w czasopismach na temat "Loosely coupled fluid-structure interaction model"
1
Sackmann, E. "Molecular and global structure and dynamics of membranes and lipid bilayers". Canadian Journal of Physics 68, nr 9 (1.09.1990): 999–1012. http://dx.doi.org/10.1139/p90-142.
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The cell plasma is a composite type of material that is made up of a two-dimensional liquid crystal (lipid–protein bilayer) to which a macromolecular network (the cytoskeleton) is loosely coupled. The latter may be approximately two dimensional as in the case of the erythrocytes or may extend throughout the whole cell cytoplasm. Owing to this combination of two states of matter, the membrane combines the dynamics and flexibility of a fluid with the mechanical stability of a solid. Owing to its low dimensionality, the local structure of the bilayer or the global shape of cells may be most effectively controlled and modulated by biochemical signals such as macromolecular adsorption. The present contribution deals with comparative studies of the local and global dynamic properties of biological and artificial membranes. In the first part the question of the physical basis of selective lipid–protein interaction mechanisms is addressed and the outstanding viscoelastic properties of plasma membranes and their role for local instabilities shape fluctuations of cells and the cell–substrate interaction are described. The second part deals with the molecular architecture and dynamics of composite membranes prepared by combining monomeric and macromolecular lipids. These model membranes open new possibilities to mimick complex mechanical processes of cell plasma membranes and to prepare low-dimensionality macromolecular solutions and gels. Finally, the use of such compound systems by nature to prepare the semipermeable protective layers of plant leaves, the so-called cuticle, is discussed. In analogy to plasma membranes, the local transport properties are modulated by variation of the liquid-crystalline state of the monomeric waxes.
2
Maurice, Pauline, Neville Hogan i Dagmar Sternad. "Predictability, force, and (anti)resonance in complex object control". Journal of Neurophysiology 120, nr 2 (1.08.2018): 765–80. http://dx.doi.org/10.1152/jn.00918.2017.
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Manipulation of complex objects as in tool use is ubiquitous and has given humans an evolutionary advantage. This study examined the strategies humans choose when manipulating an object with underactuated internal dynamics, such as a cup of coffee. The dynamics of the object renders the temporal evolution complex, possibly even chaotic, and difficult to predict. A cart-and-pendulum model, loosely mimicking coffee sloshing in a cup, was implemented in a virtual environment with a haptic interface. Participants rhythmically manipulated the virtual cup containing a rolling ball; they could choose the oscillation frequency, whereas the amplitude was prescribed. Three hypotheses were tested: 1) humans decrease interaction forces between hand and object; 2) humans increase the predictability of the object dynamics; and 3) humans exploit the resonances of the coupled object-hand system. Analysis revealed that humans chose either a high-frequency strategy with antiphase cup-and-ball movements or a low-frequency strategy with in-phase cup-and-ball movements. Counter to hypothesis 1, they did not decrease interaction force; instead, they increased the predictability of the interaction dynamics, quantified by mutual information, supporting hypothesis 2. To address hypothesis 3, frequency analysis of the coupled hand-object system revealed two resonance frequencies separated by an antiresonance frequency. The low-frequency strategy exploited one resonance, whereas the high-frequency strategy afforded more choice, consistent with the frequency response of the coupled system; both strategies avoided the antiresonance. Hence, humans did not prioritize small interaction forces but rather strategies that rendered interactions predictable. These findings highlight that physical interactions with complex objects pose control challenges not present in unconstrained movements. NEW & NOTEWORTHY Daily actions involve manipulation of complex nonrigid objects, which present a challenge since humans have no direct control of the whole object. We used a virtual-reality experiment and simulations of a cart-and-pendulum system coupled to hand movements with impedance to analyze the manipulation of this underactuated object. We showed that participants developed strategies that increased the predictability of the object behavior by exploiting the resonance structure of the object but did not minimize the hand-object interaction force.
3
Guidoboni, Giovanna, Roland Glowinski, Nicola Cavallini i Suncica Canic. "Stable loosely-coupled-type algorithm for fluid–structure interaction in blood flow". Journal of Computational Physics 228, nr 18 (październik 2009): 6916–37. http://dx.doi.org/10.1016/j.jcp.2009.06.007.
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Bukač, M. "A loosely-coupled scheme for the interaction between a fluid, elastic structure and poroelastic material". Journal of Computational Physics 313 (maj 2016): 377–99. http://dx.doi.org/10.1016/j.jcp.2016.02.051.
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Gigante, Giacomo, i Christian Vergara. "On the Choice of Interface Parameters in Robin–Robin Loosely Coupled Schemes for Fluid–Structure Interaction". Fluids 6, nr 6 (8.06.2021): 213. http://dx.doi.org/10.3390/fluids6060213.
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We consider two loosely coupled schemes for the solution of the fluid–structure interaction problem in the presence of large added mass effect. In particular, we introduce the Robin–Robin and Robin–Neumann explicit schemes where suitable interface conditions of Robin type are used. For the estimate of interface Robin parameters which guarantee stability of the numerical solution, we propose a new strategy based on the optimization of the reduction factor of the corresponding strongly coupled (implicit) scheme, by means of the optimized Schwarz method. To check the suitability of our proposals, we show numerical results both in an ideal cylindrical domain and in a real human carotid. Our results showed the effectiveness of our proposal for the calibration of interface parameters, which leads to stable results and shows how the explicit solution tends to the implicit one for decreasing values of the time discretization parameter.
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Benaroya, Haym, i Rene D. Gabbai. "Modelling vortex-induced fluid–structure interaction". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 366, nr 1868 (5.11.2007): 1231–74. http://dx.doi.org/10.1098/rsta.2007.2130.
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The principal goal of this research is developing physics-based, reduced-order, analytical models of nonlinear fluid–structure interactions associated with offshore structures. Our primary focus is to generalize the Hamilton's variational framework so that systems of flow-oscillator equations can be derived from first principles. This is an extension of earlier work that led to a single energy equation describing the fluid–structure interaction. It is demonstrated here that flow-oscillator models are a subclass of the general, physical-based framework. A flow-oscillator model is a reduced-order mechanical model, generally comprising two mechanical oscillators, one modelling the structural oscillation and the other a nonlinear oscillator representing the fluid behaviour coupled to the structural motion. Reduced-order analytical model development continues to be carried out using a Hamilton's principle-based variational approach. This provides flexibility in the long run for generalizing the modelling paradigm to complex, three-dimensional problems with multiple degrees of freedom, although such extension is very difficult. As both experimental and analytical capabilities advance, the critical research path to developing and implementing fluid–structure interaction models entails formulating generalized equations of motion, as a superset of the flow-oscillator models; and developing experimentally derived, semi-analytical functions to describe key terms in the governing equations of motion. The developed variational approach yields a system of governing equations. This will allow modelling of multiple d.f. systems. The extensions derived generalize the Hamilton's variational formulation for such problems. The Navier–Stokes equations are derived and coupled to the structural oscillator. This general model has been shown to be a superset of the flow-oscillator model. Based on different assumptions, one can derive a variety of flow-oscillator models.
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Gao, Hao, Liuyang Feng, Nan Qi, Colin Berry, Boyce E. Griffith i Xiaoyu Luo. "A coupled mitral valve—left ventricle model with fluid–structure interaction". Medical Engineering & Physics 47 (wrzesień 2017): 128–36. http://dx.doi.org/10.1016/j.medengphy.2017.06.042.
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PEGORARO, M., F. A. A. GOMES i P. R. NOVAK. "Study of modal analysis based on fluid-structure interaction". Revista IBRACON de Estruturas e Materiais 11, nr 6 (grudzień 2018): 1391–417. http://dx.doi.org/10.1590/s1983-41952018000600012.
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Abstract In this work, a coupled fluid-structure problem is approached, comparing the result with the modal analysis of a structure. The objective of this work is to analyze the physical phenomenon of fluid-structure interaction of a flexible structure. For this, the coupled problem solved using an Arbitrary Lagrangean-Eulerian (ALE) approach. As support for solving the mathematical equations of coupled problem, ANSYS® physical analysis software was used. An experimental modal analysis, using the Rational Fractional Polynomial method was developed for a small scale steel structure, and the result of this was compared with the result obtained from the model simulated in the software. Their vibration modes and natural frequencies obtained by numerical modeling were validated experimentally. Whit the numerical modeling of the modal analysis of a structure experimentally validated, attempted to analyze the dynamic behavior of the structure when it is subjected to a load due to a fluid-flow through a coupled fluid-structure problem. The results presented in this work show that the structure subjected to loads due to the fluid-flow, moves according to its vibration modes.
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Gigante, Giacomo, i Christian Vergara. "On the stability of a loosely-coupled scheme based on a Robin interface condition for fluid-structure interaction". Computers & Mathematics with Applications 96 (sierpień 2021): 109–19. http://dx.doi.org/10.1016/j.camwa.2021.05.012.
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Boilevin-Kayl, Ludovic, Miguel A. Fernández i Jean-Frédéric Gerbeau. "A Loosely Coupled Scheme for Fictitious Domain Approximations of Fluid-Structure Interaction Problems with Immersed Thin-Walled Structures". SIAM Journal on Scientific Computing 41, nr 2 (styczeń 2019): B351—B374. http://dx.doi.org/10.1137/18m1192779.
Pełny tekst źródłaRozprawy doktorskie na temat "Loosely coupled fluid-structure interaction model"
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Smith, Joshua Gabriel. "Loosely Coupled Hypersonic Airflow Simulation over a Thermally Deforming Panel with Applications for a POD Reduced Order Model". Miami University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=miami1501161884638821.
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Akgul, Mehmet. "Static Aeroelastic Analysis Of A Generic Slender Missile Using A Loosely Coupled Fluid Structure Interaction Method". Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614139/index.pdf.
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In this thesis, a loosely coupled Fluid-Structure Interaction (FSI) analysis method is developed for the solution of steady state missile/rocket aeroelastic problems. FLUENT is used as the Computational Fluid Dynamics (CFD) tool to solve Euler equations whereas ANSYS is used as the Computational Structural Dynamics (CSD) tool to solve linear structural problem. The use of two different solvers requires exchanging data between fluid and structure domains at each iteration step. Kriging interpolation method is employed for the data transfer between non-coincident fluid and structure grids. For mesh deformation FLUENT&rsquos built-in spring based smoothing approach is utilized. The study is mainly divided into two parts. In the first part static aeroelastic analysis for AGARD 445.6 wing is conducted and the results are compared with the reference studies. Deformation and pressure coefficient results are compared with reference both of which are in good agreement. In the second part, to investigate possible effects of aeroelasticity on rocket and missile configurations, static aeroelastic analysis for a canard controlled generic slender missile which is similar to a conventional 2.75&rdquo
rocket geometry is conducted and results of the analysis for elastic missile are compared with the rigid case. It is seen that the lift force produced by canards and tails lessen due to deformations, stability characteristics of the missile decreases significantly and center of pressure location changes due to the deformations in the control surfaces.
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Miller, Samuel C. "Fluid-Structure Interaction of a Variable Camber Compliant Wing". University of Dayton / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1428575972.
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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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Boilevin-Kayl, Ludovic. "Modeling and numerical simulation of implantable cardiovascular devices". Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS039.
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Cette thèse, réalisée dans le cadre du projet Mivana, est consacrée à la modélisation et à la simulation numérique de dispositifs cardiaques implantables. Ce projet est mené par les start-up Kephalios et Epygon, concepteurs de solutions chirurgicales non invasives pour le traitement de la régurgitation mitrale. La conception et la simulation de tels dispositifs nécessitent des méthodes numériques efficaces et précises capables de calculer correctement l’hémodynamique cardiaque. C’est le but principal de cette thèse. Dans la première partie, nous décrivons le système cardiovasculaire et les valves cardiaques avant de présenter quelques éléments de théorie concernant la modélisation mathématique de l’hémodynamique cardiaque. En fonction du degré de complexité adopté pour la modélisation des feuillets de la valve, deux approches sont identifiées : le modèle de surfaces résistives immergées et le modèle complet d’interaction fluide-structure. Dans la deuxième partie, nous étudions la première approche qui consiste à combiner une modélisation réduite de la dynamique des valves avec un découplage cinématique de l’hémodynamique cardiaque et de l’électromécanique. Nous l’enrichissons de données physiologiques externes pour la simulation correcte des phases isovolumétriques, pierres angulaires du battement cardiaque, permettant d’obtenir un modèle relativement précis qui évite la complexité des problèmes entièrement couplés. Ensuite, une série d’essais numériques sur des géométries 3D physiologiques, impliquant la régurgitation mitrale et plusieurs configurations de valves immergées, illustre la performance du modèle proposé. Dans la troisième et dernière partie, des modèles complets d’interaction fluide-structure sont considérés. Ce type de modélisation est nécessaire pour étudier des problèmes plus complexes où la précédente approche n’est plus satisfaisante, comme par exemple le prolapsus de la valve mitrale ou la fermeture d’une valve mécanique. D’un point de vue numérique, le développement de méthodes précises et efficaces est indispensable pour pouvoir simuler de tels cas physiologiques. Nous considérons alors une étude numérique complète dans laquelle plusieurs méthodes de maillages non compatibles sont comparées. Puis, nous présentons un nouveau schéma de couplage explicite dans le cadre d’une méthode de type domaine fictif pour lequel la stabilité inconditionnelle au sens de la norme en énergie est démontrée. Plusieurs exemples numériques en 2D sont proposés afin d’illustrer les propriétés et les performances de ce schéma. Enfin, cette méthode est finalement utilisée pour la simulation numérique 2D et 3D de dispositifs cardiovasculaires implantables dans un modèle complet d’interaction fluide-structureThis thesis, taking place in the context of the Mivana project, is devoted to the modeling and to the numerical simulation of implantable cardiovascular devices. This project is led by the start-up companies Kephalios and Epygon, conceptors of minimally invasive surgical solutions for the treatment of mitral regurgitation. The design and the simulation of such devices call for efficient and accurate numerical methods able to correctly compute cardiac hemodynamics. This is the main purpose of this thesis. In the first part, we describe the cardiovascular system and the cardiac valves before presenting some standard material for the mathematical modeling of cardiac hemodynamics. Based on the degree of complexity adopted for the modeling of the valve leaflets, two approaches are identified: the resistive immersed surfaces model and the complete fluidstructure interaction model. In the second part, we investigate the first approach which consists in combining a reduced modeling of the valves dynamics with a kinematic uncoupling of cardiac hemodynamics and electromechanics. We enhance it with external physiological data for the correct simulation of isovolumetric phases, cornerstones of the heartbeat, resulting in a relatively accurate model which avoids the complexity of fully coupled problems. Then, a series of numerical tests on 3D physiological geometries, involving mitral regurgitation and several configurations of immersed valves, illustrates the performance of the proposed model. In the third and final part, complete fluid-structure interaction models are considered. This type of modeling is necessary when investigating more complex problems where the previous approach is no longer satisfactory, such as mitral valve prolapse or the closing of a mechanical valve. From the numerical point of view, the development of accurate and efficient methods is mandatory to be able to compute such physiological cases. We then consider a complete numerical study in which several unfitted meshes methods are compared. Next, we present a new explicit coupling scheme in the context of the fictitious domain method for which the unconditional stability in the energy norm is proved. Several 2D numerical examples are provided to illustrate the properties and the performance of this scheme. Last, this method is finally used for 2D and 3D numerical simulation of implantable cardiovascular devices in a complete fluid-structure interaction framework
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Kumaresan, D. "Non-linear Vibration of Beam Immersed in Fluid". Thesis, 2018. https://etd.iisc.ac.in/handle/2005/5341.
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In space launch vehicles with liquid propulsion system, various sub-systems like gas bottles, anti-slosh baffles and fluid lines are placed inside the propellant tanks which become partially filled over time during flight. In this context, the dynamic response of a structure immersed in a fluid becomes complex as the force exerted by the fluid on the structure during vibration is very sever. Several theoretical models have been reported in literature to solve this type of fluid-structure interaction problems. However, the selection of a suitable model depends on the realistic physical condition and the numerical accuracy with which the solution has to be analyzed. The theoretical models considered here are based on (1) a loosely coupled fluid-structure interaction model, (2) a strongly coupled fluid-structure interaction model with large deformation and (3) a phenomenological fluid-structure interaction model, all of them including the effect of large deformation. The commercial code ANSYS CFX is used to study the first two models. Computational performance and accuracy aspects are discussed in detail with reference to experimental measurements. In order to apply the detailed understandings further in efficient simulation study, particularly those requiring iterative design optimization of the structural system, it is desired to have a much faster computational speed of simulation without compromising on the numerical accuracy. Model order reduction with phenomenology based mathematical models is one such approach considered further. A phenomenological fluid-structure interaction model is formulated and implemented in a new code. Data generated from an experimental study of internal fluid conveying a beam immersed partially in an external fluid environment is used to fit phenomenological model parameters. In this the problem is sub-divided into two parts. In the first part, a database is generated for the inertial force and the drag forces induced on the beam by the external fluid, and a parametric relationship is incorporated in the phenomenological model. Next a blind transient simulation of this phenomenological model is carried out with base excitation. Simulation results are compared with the experimental results which are found to be in good agreement. Potential application of the developed approach is discussed
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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 źródłaCzęści książek na temat "Loosely 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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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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Tambo, Torben, i Lars Bækgaard. "Transitioning to Government Shared Services Centres". W Public Affairs and Administration, 419–48. IGI Global, 2015. http://dx.doi.org/10.4018/978-1-4666-8358-7.ch019.
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Services are fundamental to the provisioning of business activities. Enterprise Architecture (EA) is maintaining the relationship between strategy, business, and technology. A clear definition and agreed understanding of services is critical to realising information technology artefacts. Services, however, tend to be more complex than the mere act of interaction or working processes, and should be seen out of the cultural, organisational, and managerial factors surrounding them. This chapter uses a service model consisting of execution, context, and intention with an underlying claim that all three elements must be present to make services meaningful. EA must be seen in the light of this. This chapter addresses the issues related to combined transformation of organisations, service systems, and consequently, EA. The transformation changes loosely coupled, distributed organisations into Shared Service Centres (SSCs). A case study of a far-reaching SSC transformation from Denmark is presented where eGovernment services are moved from local government level into a national SSC structure referred to as Udbetaling Danmark (lit. PayDK). Major findings include: (1) When eGovernment reaches a certain level of maturity, it dissolves its original reason and no longer follows a progressive maturity model. Instead, it leads to a more radical reorganisation emphasising operational efficiency. (2) Development and management of complexities and uncertainties in governmental administrative services are closely associated with the development of eGovernment through ongoing refinement of EA and service frameworks. (3) The policy-driven reshaping of governmental services, originally themselves being SSCs, can lead to iterative SSC formations, each seeking to establish a professional logic of its own. (4) The systemic perception connected to EA and service science provides valuable insight into service transformation before, during, and after the transformation. This chapter aims at a deeper understanding and discussion of services in developing eGovernment policies and architectures, but findings are readily applicable in general business environments.
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Tambo, Torben, i Lars Bækgaard. "Transitioning to Government Shared Services Centres". W Advances in Business Information Systems and Analytics, 361–91. IGI Global, 2014. http://dx.doi.org/10.4018/978-1-4666-4518-9.ch011.
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Services are fundamental to the provisioning of business activities. Enterprise Architecture (EA) is maintaining the relationship between strategy, business, and technology. A clear definition and agreed understanding of services is critical to realising information technology artefacts. Services, however, tend to be more complex than the mere act of interaction or working processes, and should be seen out of the cultural, organisational, and managerial factors surrounding them. This chapter uses a service model consisting of execution, context, and intention with an underlying claim that all three elements must be present to make services meaningful. EA must be seen in the light of this. This chapter addresses the issues related to combined transformation of organisations, service systems, and consequently, EA. The transformation changes loosely coupled, distributed organisations into Shared Service Centres (SSCs). A case study of a far-reaching SSC transformation from Denmark is presented where eGovernment services are moved from local government level into a national SSC structure referred to as Udbetaling Danmark (lit. PayDK). Major findings include: (1) When eGovernment reaches a certain level of maturity, it dissolves its original reason and no longer follows a progressive maturity model. Instead, it leads to a more radical reorganisation emphasising operational efficiency. (2) Development and management of complexities and uncertainties in governmental administrative services are closely associated with the development of eGovernment through ongoing refinement of EA and service frameworks. (3) The policy-driven reshaping of governmental services, originally themselves being SSCs, can lead to iterative SSC formations, each seeking to establish a professional logic of its own. (4) The systemic perception connected to EA and service science provides valuable insight into service transformation before, during, and after the transformation. This chapter aims at a deeper understanding and discussion of services in developing eGovernment policies and architectures, but findings are readily applicable in general business environments.
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Lu, Xinggan, Kun Jiang, Shenshen Cheng i Hao Wang. "A Fluid-Structure Coupling Method to Predict the Interior Ballistic Characteristic of Gas Generator with Complex Structures". W Advances in Transdisciplinary Engineering. IOS Press, 2022. http://dx.doi.org/10.3233/atde220070.
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For gas generators based on pyrotechnic technology, as the structure becomes more complex, the internal ballistic characteristic is no longer just related to the flow field generated by propellant combustion. The fluid-structure interaction in the system plays an important role. In order to accurately predict the internal ballistic characteristic of the gas generator, a mathematical model of coupling the flow field generated by propellant combustion and the structural evolution in the system is established. The interior ballistic model is utilized to calculate the flow field generated by propellant combustion, and the finite element method is applied to simulate the structural evolution. The flow field and the structural evolution are coupled through a user subroutine interface in ABAQUS. The accuracy of the coupled model is verified by experiment, and the precision of the traditional classical interior ballistic model is compared with that of the coupled model. The results show that the pressure prediction error of the traditional classical interior ballistic model is more than 46% for gas generators with complex structures. While the coupling model is in great agreement with the experiment, and the error of pressure prediction is less than 5.0%.
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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.
Streszczenia konferencji na temat "Loosely coupled fluid-structure interaction model"
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Moghaddaszade-Kermani, Ahmad, Peter Oshkai i Afzal Suleman. "Fluid-Structure Interaction Simulation of Blood Flow Inside a Diseased Left Ventricle With Obstructive Hypertrophic Cardiomyopathy in Early Systole". W ASME 2009 Fluids Engineering Division Summer Meeting. ASMEDC, 2009. http://dx.doi.org/10.1115/fedsm2009-78381.
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Mitral-Septal contact has been proven to be the cause of obstruction in the left ventricle with hypertrophic cardiomyopathy (HC). This paper presents a study on the fluid mechanics of obstruction using two-way loosely coupled fluid-structure interaction (FSI) methodology. A parametric model for the geometry of the diseased left ventricular cavity, myocardium and mitral valve has been developed, using the dimensions extracted from magnetic resonance images. The three-element Windkessel model [1] was modified for HC and solved to introduce pressure boundary condition to the aortic aperture in the systolic phase. The FSI algorithm starts at the beginning of systolic phase by applying the left ventricular pressure to the internal surface of the myocardium to contract the muscle. The displacements of the myocardium and mitral leaflets were calculated using the nonlinear finite element hyperelastic model [2] and subsequently transferred to the fluid domain. The fluid mesh was moved accordingly and the Navier-Stokes equations were solved in the laminar regime with the new mesh using the finite volume method. In the next time step, the left ventricular pressure was increased to contract the muscle further and the same procedure was repeated for the fluid solution. The results show that blood flow jet applies a drag force to the mitral leaflets which in turn causes the leaflet to deform toward the septum thus creating a narrow passage and possible obstruction.
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Moffatt, Stuart, i Li He. "Blade Forced Response Prediction for Industrial Gas Turbines: Part 1 — Methodologies". W ASME Turbo Expo 2003, collocated with the 2003 International Joint Power Generation Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/gt2003-38640.
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Forming the first part of a two-part paper, the methodology of an efficient frequency-domain approach for predicting the forced response of turbomachinery blades is presented. The capability and computational efficiency of the method are demonstrated in Part Two with a three-stage transonic compressor case. Interaction between fluid and structure is dealt with in a loosely coupled manner, based on the assumption of linear aerodynamic damping and negligible frequency shift. The Finite Element (FE) package ANSYS is used to provide the mode shape and natural frequency of a particular mode, which is interpolated onto the CFD mesh. The linearised unsteady Navier-Stokes equations are solved in the frequency domain using a single-passage approach to provide aerodynamic excitation and damping forces. Two methods of obtaining the single degree-of-freedom forced response solution are demonstrated: the Modal Reduction Technique, solving the modal forced response equation in modal space; and a new Energy Method, an alternative method allowing calculations to be performed directly and simply in physical space. Both methods are demonstrated in a preliminary case study of the NASA R67 transonic fan blade with excitation of the 1st torsion mode due to a hypothetical inlet distortion.
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Ducoin, Antoine, Yin Lu Young i Jean-Franc¸ois Sigrist. "Hydroelastic Responses of a Flexible Hydrofoil in Turbulent, Cavitating 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-icnmm2010-30310.
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The objective of this work is to develop and validate a robust method to simulate the hydroelastic responses of flexible hydrofoil in turbulent, cavitating flow. A two degrees-of-freedom (2-DOF) model is used to simulate the plunging and pitching motion at the foil tip due to bending and twisting deformation of a 3-D cantilevered hydrofoil. The 2-DOF model is loosely coupled with the commercial computational fluid dynamics (CFD) solver STAR-CCM+ to efficiently simulate the fluid-structure interaction (FSI) responses of a cantilevered, rectangular hydrofoil. The numerical predictions are compared with experimental measurements for cases with and without cavitation. The experimental studies were conducted in the cavitation tunnel at the French Naval Academy (IRENav), France. Only quasi-steady cases with Reynolds number (Re) of 750,000 are shown in this paper. In general, the numerical results agree well with the experimental measurements and observations. The results show that elastic deformation of the POM polyacetate (flexible) hydrofoil lead to increases in the angle of attack, which resulted in higher lift and drag coefficients, lower lift to drag ratio, and longer cavities compared to the stainless steel (rigid) hydrofoil. Whereas only stable cavitation cases are considered in this paper, significant interaction effects were observed during experiments for cases with unstable cavitation due to interations between the foil natural frequencies and the cavity shedding frequencies. Transient analysis of the FSI responses of 3-D elastic hydrofoils in turbulent, cavitating flow is currently under work.
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Hassan, Marwan. "Simulation of Fluidelastic Vibrations of Heat Exchanger Tubes With Loose Supports". W ASME 2006 Pressure Vessels and Piping/ICPVT-11 Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/pvp2006-icpvt-11-93899.
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Fluidelastic instability is regarded as the most complex and destructive flow excitation mechanism in heat exchanger tube arrays subjected to cross fluid flow. Several attempts have been made for modelling fluidelastic instability in tube arrays in order to predict the stability threshold. However, fretting wear prediction requires a nonlinear computation of the tube dynamics in which proper modelling of the fluid forcing function is essential. In this paper, a time domain simulation of fluidelastic instability is presented for a single flexible tube in an otherwise rigid array subjected to cross fluid flow. The model is based on the unsteady flow theory proposed by Lever and Weaver [1] and Yetisir and Weaver [2]. The developed model has been implemented in INDAP (Incremental Nonlinear Dynamic Analysis Program), an in-house finite element code. Numerical investigations were performed for two linear tube-array geometries and compared with published experimental data. A reasonable agreement between the numerical simulation and the experimental results was obtained. The fluidelastic force model was also coupled with a tube/support interaction model. The developed numerical model was utilized to study a loosely-supported cantilever tube subjected to air flow. Tube-to-support clearance, random excitation level, and flow velocity were then varied. The results indicated that the loose support has a stabilizing effect on the tube response. Both rms impact force and normal work rate increased as a result of increasing the flow velocity or the support radial clearance. Contact ratio exhibited a sharp increase at a flow velocity higher than the instability threshold of the first unsupported mode. In addition, an interesting behaviour has been observed, namely the change of tube’s equilibrium position due to fluid forces. This causes a single-sided impact. At a higher turbulence level, double-sided impact conditions were dominant. The influence of these dynamic regimes on the tube/support parameters was also addressed.
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Kanitz, Manuela, i Juergen Grabe. "Influence of Suction Dredging on the Failure Mechanism of Sandy Submarine Slopes: Revisited With a Coupled Numerical Approach". W ASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/omae2019-95151.
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Abstract The installation of shallow foundation systems for offshore wind turbines like gravity foundations requires the excavation of the weak top soil of the seabed to place the structure on more stable ground. This excavation can be done through suction dredging resulting in a pit. Different slope angles of this pit can be realized using this technique. As the failure mechanisms of artificial submarine slopes using suction dredging are barely investigated, relatively small final slope angles of max. 10 degree are reached to guarantee stability. Nevertheless, small-scale experiments show that submarine slopes with overcritical slope inclinations can be stable for a while when prepared with suction dredging. Steeper inclinations would significantly reduce the disturbance of the marine fauna and the amount of sand to be removed and therefore meet both economic and ecological interests. The investigations of the failure mechanism in the submarine slope during suction dredging are carried out with a coupled Euler-Lagrange approach, namely the combination of the Computational Fluid Dynamics (CFD) and the Discrete Element Method (DEM). This method enables the computation of particle-particle as well as the fluid-particle interaction forces and hence their influence on the investigated submarine slope behavior. The calculations are carried out with the open source software package CFDEM® coupling, which combines the discrete element code LIGGGHTS® with CFD solvers based on OpenFOAM®. Additionally, small scale model tests of suction dredging of sandy submarine slopes are carried out. The displacement of the soil grains is monitored with a high-speed camera. To take into account effects of contractancy and dilatancy, a loosely and a densely packed sand are investigated and the influence of the packing density on the failure mechanism is evaluated. The experimentally gained results will be compared to the numerical ones to evaluate the capability of the coupled CFD-DEM method to depict the failure behavior of submarine slopes during suction dredging.
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Jaiman, Rajeev, Philippe Geubelle, Eric Loth i Xiangmin Jiao. "Stable and Accurate Loosely-Coupled Scheme for Unsteady Fluid-Structure Interaction". W 45th AIAA Aerospace Sciences Meeting and Exhibit. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2007. http://dx.doi.org/10.2514/6.2007-334.
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Seeley, Charles, Sunil Patil, Andy Madden, Stuart Connell, Gwenael Hauet i Laith Zori. "Hydro Francis Runner Stability and Forced Response Calculations". W ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-90456.
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Abstract Hydroelectric power generation accounts for 7% of the total world electric energy production. Francis turbines are often employed in large-scale hydro projects and represent 60% of the total installed base. Outputs up to 800 MW are available and efficiencies of 95% are common. Cost, performance, and design cycle time are factors that continue to drive new designs as well as retrofits. This motivates the development of more sophisticated analysis tools to better assess runner performance earlier in the design phase. The focus of this paper is to demonstrate high fidelity and time-efficient runner damping and forced response calculations based on one-way fluid-structure interaction (FSI) using loosely coupled commercial finite element analysis (FEA) and computational fluid dynamics (CFD) codes. The runner damping is evaluated based on the work done by the fluid on the runner. The calculation of the work first involves determining the runner mode shapes and natural frequencies using a cyclic symmetric FEA model with structural elements to represent the runner hardware, and acoustic fluid elements to represent the mass loading effect of the fluid. The mode shapes are then used in a transient CFD calculation to determine the damping which represents the work done by the fluid on the runner. Positive damping represents stability from flutter perspective while negative damping represents unstable operating conditions. A transient CFD calculation was performed on a runner to obtain engine order forcing function from upstream stationary vanes. This unsteady forcing function was mapped to the FEA model. Care is taken to account for the proper inter-blade phase angle on the cyclic symmetric model. The hydraulic damping from flutter calculations was also provided as input to the forced response. The forced response is then determined using this equivalent proportional damping and modal superposition of the FEA model that includes both the structural and acoustic elements. Results of the developed analysis procedure are presented based on the Tokke runner, that has been the basis of several studies through the Norwegian HydroPower Center. Unique features of the workflow and modeling approaches are discussed in detail. Benefits and challenges for both the FEA model and the CFD model are discussed. The importance of the hydraulic damping, that is traditionally ignored in previous analysis is discussed as well. No validation data is available for the forced response, so this paper is focused on the methodology for the calculations.
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Vasanthakumar, Parthasarathy, i Paul-Benjamin Ebel. "Forced Response Analysis of a Transonic Fan". W ASME Turbo Expo 2012: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/gt2012-69867.
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The forced response of turbomachinery blades is a primary source of high cycle fatigue (HCF) failure. This paper deals with the computational prediction of blade forced response of a transonic fan stage that consists of a highly loaded rotor along with a tandem stator. In the case of a transonic fan, the forced response of the rotor due to the downstream stator assumes significance because of the transonic flow field. The objective of the present work is to determine the forced response of the rotor induced as a result of the unsteady flow field due to the downstream stator vanes. Three dimensional, Navier-Stokes flow solver TRACE is used to numerically analyse the forced response of the fan. A total of 11 resonant crossings as identified in the Campbell diagram are examined and the corresponding modeshapes are obtained from finite element modal analysis. The interaction between fluid and structure is dealt with in a loosely coupled manner based on the assumption of linear aerodynamic damping. The aerodynamic forcing is obtained by a nonlinear unsteady Navier-Stokes computation and the aerodynamic damping is obtained by a time-linearized Navier-Stokes computation. The forced response solution is obtained by the energy method allowing calculations to be performed directly in physical space. Using the modal forcing and damping, the forced response amplitude can be directly computed at the resonance crossings. For forced response solution, the equilibrium amplitude is reached when the work done on the blade by the external forcing function is equal to the work done by the system damping (aerodynamic and structural) force. A comprehensive analysis of unsteady aerodynamic forces on the rotor blade surface as a result of forced response of a highly loaded transonic fan is carried out. In addition, the correspondence between the location of high stress zones identified from the finite element analysis and the regions of high modal force identified from the CFD analysis is also discussed.
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Debrabandere, F., B. Tartinville, Ch Hirsch i G. Coussement. "Fluid-Structure Interaction Using a Modal Approach". W ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/gt2011-45692.
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A new method for Fluid-Structure Interaction (FSI) predictions is here introduced, based on a Reduced-Order Model (ROM) for the structure, described by its mode shapes and natural frequencies. A linear structure is assumed as well as Rayleigh damping. A two-way coupling between the fluid and the structure is ensured by a loosely-coupling staggered approach: the aerodynamic loads computed by the flow solver are used to determine the deformations from the modal equations, which are sent back to the flow solver. The method is firstly applied to a clamped beam oscillating under the effect of von Karman vortices. The results are compared to a full-order model. Then a flutter application is considered on the AGARD wing 445.6. Finally, the modal approach is applied to the aeroelastic behavior of an axial compressor stage. The influence of passing rotor blade wakes on the downstream stator blades is investigated.
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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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