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Magneto-fluid-structure interaction issues for vibrating rigid bodies in conducting fluids: The numerical and the analytical approaches

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COMPUTERS & structureS 2018年 210卷 41-57页

作者： Li, Ming-Jian Zhang, Nian-Mei Ni, Ming-Jiu Univ Chinese Acad Sci Sch Engn Sci Beijing 101408 Peoples R China

To study the magneto-fluid-structure interaction (MFSI) problems for rigid bodies and conducting fluids, a numerical method and an analytical approach have been carried out. The numerical scheme is based on a partitioned arbitrary Lagrangian-Eulerian framework, and is suitable for viscous, incompressible magneto-fluid-structure interaction simulation, A displacement prediction-pressure stabilization scheme has been established to enhance the stability and efficiency. Meanwhile, a consistent and conservative scheme for deforming configurations has been developed. This method can numerically ensure the divergence-free condition of the current density, and can conserve the momentum from the Lorentz forces after grids update. The analytical approach has considered a vibrating cylinder surrounded by confined fluids in a magnetic field. By assuming a small amplitude and a low magnetic Reynolds number, the analytical solution can describe the temporal and spatial distribution of the fluid fields, the electromagnetic fields, and the solid motion. These solutions are also suitable for general fluid-structure interaction (FSI) problems. Comparative results suggest good agreement between the two methods developed in this paper. Nonlinear effects of the magnetic fields were presented and discussed based on the numerical results. These cases are based on careful validations, and can hopefully be used for future verification and validation work. (C) 2018 Elsevier Ltd. All rights reserved.

关键词： fluid-structure interaction Benchmark case Analytical solution MHD Magneto-fluid-structure interaction

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A numerical study of the effect of fluid-structure interaction on transient natural convection in an air-filled square cavity

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INTERNATIONAL JOURNAL OF THERMAL SCIENCES 2018年 128卷 1-14页

作者： Raisi, A. Arvin, I. Shahrekord Univ Engn Fac POB 115 Shahrekord Iran Shahrekord Univ Engn Fac Mech Engn POB 115 Shahrekord Iran

The present study aims to investigate the transient natural convection in an air-filled square cavity based on the effects of fluid-structure interaction (FSI). The Prandtl number of air is assumed to be 0.71. A thin deformable baffle is horizontally located in the center of the cavity and the top wall of the cavity is also elastic. The horizontal walls are completely insulated. Initially, the cavity is set at T-c temperature, then the left side wall temperature is raised to T-h. The arbitrary Lagrangian-Eulerian approach is implemented to study the flow field in the presented model. The fluid field equations are discretized by Galerkin finite element method. Further, the dimensionless equations of flexible parts of the cavity are solved using the Newton-Raphson method. The study examines the effects of Rayleigh number and baffle length on flow and temperature fields, heat transfer rate and deformation of elastic parts of the cavity. The results show that an increase in the Rayleigh number enhances the natural convection and increases the elastic parts deformations. Finally, the increase of baffle length has different effects on thermal performance of cavity depending on the Rayleigh number and rigidness or flexibility of the system.

关键词： fluid-structure interaction Square cavity Transient natural convection Elastic baffle

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A unified continuum and variational multiscale formulation for fluids, solids, and fluid-structure interaction

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COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING 2018年第Aug.1期337卷 549-597页

作者： Liu, Ju Marsden, Alison L. Stanford Univ Dept Pediat Cardiol Bioengn Clark Ctr E1-3318 Campus Dr Stanford CA 94305 USA Stanford Univ Inst Computat & Math Engn Clark Ctr E1-3318 Campus Dr Stanford CA 94305 USA

We develop a unified continuum modeling framework using the Gibbs free energy as the thermodynamic potential. This framework naturally leads to a pressure primitive variable formulation for the continuum body, which is well-behaved in both compressible and incompressible regimes. Our derivation also provides a rational justification of the isochoric-volumetric additive split of free energies in nonlinear elasticity. The variational multiscale analysis is performed for the continuum model to construct a foundation for numerical discretization. We first consider the continuum body instantiated as a hyperelastic material and develop a variational multiscale formulation for the hyper-elastodynamic problem. The generalized-a method is applied for temporal discretization. A segregated algorithm for the nonlinear solver, based on the original idea introduced in Scovazzi et al. (2016), is carefully analyzed. Second, we apply the new formulation to construct a novel unified formulation for fluid-solid coupled problems. The variational multiscale formulation is utilized for spatial discretization in both fluid and solid subdomains. The generalized-alpha method is applied for the whole continuum body, and optimal high-frequency dissipation is achieved in both fluid and solid subproblems. A new predictor multi-corrector algorithm is developed based on the segregated algorithm. The efficacy of the new formulations is examined in several benchmark problems. The results indicate that the proposed modeling and numerical methodologies constitute a promising technology for biomedical and engineering applications, particularly those necessitating incompressible models. (C) 2018 Elsevier B.V. All rights reserved.

关键词： Nonlinear continuum mechanics Incompressible solids Gibbs free energy Variational multiscale method Generalized-alpha method fluid-structure interaction

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A family of position- and orientation-independent embedded boundary methods for viscous flow and fluid-structure interaction problems

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JOURNAL OF COMPUTATIONAL PHYSICS 2018年 365卷 74-104页

作者： Huang, Daniel Z. De Santis, Dante Farhat, Charbel Stanford Univ Inst Computat & Math Engn Stanford CA 94305 USA Stanford Univ Dept Aeronaut & Astronaut Stanford CA 94305 USA Stanford Univ Dept Mech Engn Stanford CA 94305 USA Nucl Res & Consultancy Grp Westerduinweg 3 NL-1755LE Petten Netherlands

The Finite Volume method with Exact two-material Riemann Problems (FIVER) is both a computational framework for multi-material flows characterized by large density jumps, and an Embedded Boundary Method (EBM) for computational fluid dynamics and highly nonlinear fluid-structure interaction (FSI) problems. This paper deals with the EBM aspect of FIVER. For FSI problems, this EBM has already demonstrated the ability to address viscous effects along wall boundaries, and large deformations and topological changes of such boundaries. However, like for most EBMs - also known as immersed boundary methods - the performance of FIVER in the vicinity of a wall boundary can be sensitive with respect to the position and orientation of this boundary relative to the embedding mesh. This is mainly due to ill-conditioning issues that arise when an embedded interface becomes too close to a node of the embedding mesh, which may lead to spurious oscillations in the computed solution gradients at the wall boundary. This paper resolves these issues by introducing an alternative definition of the active/inactive status of a mesh node that leads to the removal of all sources of potential ill-conditioning from all spatial approximations performed by FIVER in the vicinity of a fluid-structure interface. It also makes two additional contributions. The first one is a new procedure for constructing the fluid-structure half Riemann problem underlying the semi-discretization by FIVER of the convective fluxes. This procedure eliminates one extrapolation from the conventional treatment of the wall boundary conditions and replaces it by an interpolation, which improves robustness. The second contribution is a post-processing algorithm for computing quantities of interest at the wall that achieves smoothness in the computed solution and its gradients. Lessons learned from these enhancements and contributions that are triggered by the new definition of the status of a mesh node are then generalized an

关键词： Compressible flows Embedded boundary method Finite volume method fluid-structure interaction Immersed boundary method Turbulent flows

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Thermal analysis of the dentine tubule under hot and cold stimuli using fluid-structure interaction simulation

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BIOMECHANICS AND MODELING IN MECHANOBIOLOGY 2018年第6期17卷 1599-1610页

作者： Gholampour, Seifollah Jalali, Amin Islamic Azad Univ North Tehran Branch Dept Biomed Engn POB *** Tehran Iran

The objective of this study is to compare the thermal stress changes in the tooth microstructures and the hydrodynamic changes of the dental fluid under hot and cold stimuli. The dimension of the microstructures of eleven cats' teeth was measured by scanning electron microscopy, and the changes in thermal stress during cold and hot stimulation were calculated by 3D fluid-structure interaction modeling. Evaluation of results, following data validation, indicated that the maximum velocities in cold and hot stimuli were -410.2 +/- 17.6 and +205.1 +/- 8.7 mu m/s, respectively. The corresponding data for maximum thermal stress were -20.27 +/- 0.79 and +10.13 +/- 0.24cmHg, respectively. The thermal stress caused by cold stimulus could influence almost 2.9 times faster than that caused by hot stimulus, and the durability of the thermal stress caused by hot stimulus was 71% greater than that by cold stimulus under similar conditions. The maximum stress was on the tip of the odontoblast, while the stress in lateral walls of the odontoblast and terminal fibril was very weak. There is hence a higher possibility of pain transmission with activation of stress-sensitive ion channels at the tip of the odontoblast. The maximum thermal stress resulted from the cold stimulus is double that produced by the hot stimulus. There is a higher possibility of pain transmission in the lateral walls of the odontoblast and terminal fibril by releasing mediators during the cold stimulation than the hot stimulation. These two reasons can be associated with a greater pain sensation due to intake of cold liquids.

关键词： Hydrodynamic theory Odontoblastic transduction theory Intensity of thermal stress fluid-structure interaction Scanning electron microscopy

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Dynamic characteristics identification of two graphite bricks in molten salt reactor considering fluid-structure interaction

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NUCLEAR ENGINEERING AND DESIGN 2018年 335卷 409-416页

作者： Zhong, Yang Yang, Xiong Ding, Dong Zou, Yang Tsang, D. K. L. Chinese Acad Sci Shanghai Inst Appl Phys Dept Nucl Reactor Mat & Engn Shanghai 201800 Peoples R China Univ Chinese Acad Sci Beijing 100049 Peoples R China

Graphite core plays a very important role in thorium molten salt reactor (TMSR) served as a reflector, a moderator as well as a structural material. The whole graphite core is submerged in molten salt during operation and consists of a large number of graphite bricks interconnected with keys and dowels. The molten salt as a fluid will affect the dynamic behavior of the graphite core. This phenomenon is called fluid-structure interaction (FSI). In order to maintain the integrity of the graphite core under a seismic event, it is essential to predict dynamic characteristics of the graphite bricks affected by FSI. In this paper a 1/4 scaled-down test model derived from similarity analysis will be presented. The nonlinear response of the graphite brick under the excitation of the sinusoidal harmonic is regarded as a single degree of freedom system. The dynamic characteristics of added mass and added damping can be obtained by fitting the time history of models' displacement subjected to simple harmonic motion. The experimental results shown that the added mass and the added damping are strongly dependent on the gap size between two bricks. Furthermore, a three-dimensional finite element model has been derived for the dynamic analysis of two graphite bricks with molten salt and the modelling parameters are obtained from the experiment. We found that the results from the numerical method are in good agreement with the experiment.

关键词： Nuclear graphite fluid-structure interaction Added mass Added damping ABAQUS

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An eccentric 3-D fluid-structure interaction model for investigating the effects of rod parallel offset on reciprocating-seal performance

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TRIBOLOGY INTERNATIONAL 2018年 128卷 279-290页

作者： Peng, Chao Guo, Shengrong Ouyang, Xiaoping Zhou, Qinghe Yang, Huayong Zhejiang Univ State Key Lab Fluid Power & Mechatron Syst Zheda Rd 38 Hangzhou 310027 Zhejiang Peoples R China Aviat Key Lab Sci & Technol Aero Electromech Syst Shuige Rd 33 Nanjing 211106 Jiangsu Peoples R China

The rod parallel offset ruins the axial symmetry of reciprocating seals, making the traditional 2-D model inappropriate for quantitative analysis. We propose an eccentric 3-D fluid-structure interaction (FSI) model, comprising the parallel-offset and mixed-lubrication sub-models to investigate the influence of parallel offset on the seal's micro- and macro-performance. Details of the sealing zone, friction and leakage features are analyzed for an O-ring seal at different eccentric distances, system pressures and velocities. Comparisons between the friction characteristics in the mixed-lubrication and dry conditions are also implemented in this paper.

关键词： Reciprocating seal Parallel offset Eccentric fluid-structure interaction

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Non-body-fitted fluid-structure interaction: Divergence-conforming B-splines, fully-implicit dynamics, and variational formulation

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JOURNAL OF COMPUTATIONAL PHYSICS 2018年 374卷 625-653页

作者： Casquero, Hugo Zhang, Yongjie Jessica Bona-Casas, Carles Dalcin, Lisandro Gomez, Hector Carnegie Mellon Univ Dept Mech Engn Pittsburgh PA 15213 USA Univ Illes Balears Dept Fis Palma De Mallorca 07122 Spain Univ Illes Balears IAC3 Palma De Mallorca 07122 Spain King Abdullah Univ Sci & Technol Extreme Comp Res Ctr Thuwal 23955 Saudi Arabia Purdue Univ Sch Mech Engn W Lafayette IN 47907 USA

Immersed boundary (IB) methods deal with incompressible visco-elastic solids interacting with incompressible viscous fluids. A long-standing issue of IB methods is the challenge of accurately imposing the incompressibility constraint at the discrete level. We present the divergence-conforming immersed boundary (DCIB) method to tackle this issue. The DCIB method leads to completely negligible incompressibility errors at the Eulerian level and various orders of magnitude of increased accuracy at the Lagrangian level compared to other IB methods. Furthermore, second-order convergence of the incompressibility error at the Lagrangian level is obtained as the discretization is refined. In the DCIB method, the Eulerian velocity-pressure pair is discretized using divergence-conforming B-splines, leading to inf-sup stable and pointwise divergence-free Eulerian solutions. The Lagrangian displacement is discretized using non-uniform rational B-splines, which enables to robustly handle large mesh distortions. The data transfer needed between the Eulerian and Lagrangian descriptions is performed at the quadrature level using the same spline basis functions that define the computational meshes. This conduces to a fully variational formulation, sharp treatment of the fluid-solid interface, and a 0.5 increase in the convergence rate of the Eulerian velocity and the Lagrangian displacement measured in L-2 norm in comparison with using discretized Dirac delta functions for the data transfer. By combining the generalized-alpha method and a block-iterative solution strategy, the DCIB method results in a fully-implicit discretization, which enables to take larger time steps. Various two- and three-dimensional problems are solved to show all the aforementioned properties of the DCIB method along with mesh-independence studies, verification of the numerical method by comparison with the literature, and measurement of convergence rates. (C) 2018 Elsevier Inc. All rights reserved.

关键词： fluid-structure interaction Immersed boundary method Incompressibility Isogeometric analysis Divergence-conforming B-splines Divergence-conforming immersed boundary method

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Stochastic dynamic analysis of marine risers considering fluid-structure interaction and system uncertainties

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ENGINEERING structureS 2019年 198卷 109507-000页

作者： Ni, Pinghe Li, Jun Hao, Hong Xia, Yong Du, Xiuli Beijing Univ Technol Minist Educ Key Lab Urban Secur & Disaster Engn Beijing Peoples R China Curtin Univ Sch Civil & Mech Engn Ctr Infrastruct Monitoring & Protect Kent St Bentley WA 6102 Australia Guangzhou Univ Sch Civil Engn Guangzhou 510006 Guangdong Peoples R China Hong Kong Polytech Univ Dept Civil & Environm Engn Hung Hom Kowloon Hong Kong Peoples R China

Stochastic dynamic analysis of offshore structures considering both fluid-structure interaction and system uncertainties is a challenging research task. This paper proposes a novel method to evaluate the statistical characteristics of offshore structural responses with consideration of uncertainties in the fluid and structure. The fluid behavior is simulated by a finite number of particles with particle finite element method (PFEM), and the dynamic behavior of the offshore structure is modelled with finite element method (FEM). A PFEM-FEM scheme is used to model the fluid-structure interaction. To evaluate the statistical characteristics, spectral representations method is used for uncertainty propagation. The output of fluid particles position/pressure, structural vibration, etc. are represented by using polynomial chaos (PC) expansion, and their coefficients are obtained from the least squares method. Statistical characteristics of the responses, such as mean value and variance, can be evaluated with the obtained PC coefficients. Three numerical examples are studied in this paper. The first example is a simple structural model, which is used to demonstrate the convergence and accuracy of the uncertainty analysis method. The second example is a benchmark dam break problem. Statistical characteristics of the fluid particles position due to uncertainties in the mass density are evaluated. Numerical results are verified with experimental data and observations. In the third example, PFEM-FEM scheme is used to conduct fluid- structure interaction analysis. The marine riser structure is modelled with beam elements. In the fluid domain, PFEM is used. Uncertainties in both the fluid domain and structural domain are considered. Results demonstrate that the proposed approach can be used to evaluate the statistical characteristics of responses in the fluid-structure interaction analysis accurately and efficiently.

关键词： Polynomial chaos expansion Particle finite element method fluid-structure interaction Uncertainty analysis Stochastic Non-intrusive method

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A framework for designing patient-specific bioprosthetic heart valves using immersogeometric fluid-structure interaction analysis

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INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2018年第4期34卷 e2938-e2938页

作者： Xu, Fei Morganti, Simone Zakerzadeh, Rana Kamensky, David Auricchio, Ferdinando Reali, Alessandro Hughes, Thomas J. R. Sacks, Michael S. Hsu, Ming-Chen Iowa State Univ Dept Mech Engn Black Engn 2025 Ames IA 50011 USA Univ Pavia Dept Elect Comp & Biomed Engn Via Ferrata 3 I-27100 Pavia Italy Univ Texas Austin Ctr Cardiovasc Simulat Inst Computat Engn & Sci 201 East 24th StStop C0200 Austin TX 78712 USA Univ Calif San Diego Dept Struct Engn 9500 Gilman DrMail Code 0085 La Jolla CA 92093 USA Univ Pavia Dept Civil Engn & Architecture Via Ferrata 3 I-27100 Pavia Italy

Numerous studies have suggested that medical image derived computational mechanics models could be developed to reduce mortality and morbidity due to cardiovascular diseases by allowing for patient-specific surgical planning and customized medical device design. In this work, we present a novel framework for designing prosthetic heart valves using a parametric design platform and immersogeometric fluid-structure interaction (FSI) analysis. We parameterize the leaflet geometry using several key design parameters. This allows for generating various perturbations of the leaflet design for the patient-specific aortic root reconstructed from the medical image data. Each design is analyzed using our hybrid arbitrary Lagrangian-Eulerian/immersogeometric FSI methodology, which allows us to efficiently simulate the coupling of the deforming aortic root, the parametrically designed prosthetic valves, and the surrounding blood flow under physiological conditions. A parametric study is performed to investigate the influence of the geometry on heart valve performance, indicated by the effective orifice area and the coaptation area. Finally, the FSI simulation result of a design that balances effective orifice area and coaptation area reasonably well is compared with patient-specific phase contrast magnetic resonance imaging data to demonstrate the qualitative similarity of the flow patterns in the ascending aorta.

关键词： bioprosthetic heart valves fluid-structure interaction immersogeometric analysis isogeometric analysis parametric design patient specific

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