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A partitioned framework for coupling LBM and FEM through an implicit IBM allowing non-conforming time-steps: Application to fluid-structure interaction in biomechanics

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JOURNAL OF COMPUTATIONAL PHYSICS 2022年 449卷 110786-110786页

作者： Li, Zhe Oger, Guillaume Le Touze, David Ecole Cent Nantes ECN LHEEA Res Dept Nantes France CNRS Nantes France

This paper presents a partitioned framework for the numerical simulation of fluid-structure interactions by coupling the lattice Boltzmann method (LBM) and the finite element method (FEM). The two numerical methods LBM and FEM are coupled with an implicit immersed boundary method (IBM) in a strong way, which ensures exactly the no-slip condition and the continuities of velocity and stress at the fluid-solid interface and each instant in time. In the proposed partitioned coupling procedure, the coupling system of equations are first established and then condensed to the interface. By solving the condensed coupling system of equations, the interface force field is obtained and sent to both solvers to accomplish time integrations in each sub-domain. In addition, two strategies based on linear interpolation in time are proposed to handle the cases with non-conforming time-steps in the fluid and solid sub-domains. Through several 2D and 3D numerical test-cases on the mechanical heart valve, the fluid-induced vibration of a deformable solid beam, the flapping flag, the proposed coupling framework is validated with good agreements with references. Finally, a test-case on the interaction between the blood flow and the aortic valve is carried out, showing the applicability of the present framework in realistic biomechanical applications. (C) 2021 Elsevier Inc. All rights reserved.

关键词： Strong partitioned coupling Lattice Boltzmann method Finite element method Implicit immersed boundary method fluid-structure interaction Non-conforming time-steps

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A block-based adaptive particle refinement SPH method for fluid-structure interaction problems

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COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING 2022年 399卷 1页

作者： Gao, Tianrun Qiu, Huihe Fu, Lin Hong Kong Univ Sci & Technol Dept Mech & Aerosp Engn Kowloon Clear Water Bay Hong Kong Peoples R China Hong Kong Univ Sci & Technol Dept Math Kowloon Clear Water Bay Hong Kong Peoples R China Hong Kong Univ Sci & Technol Shenzhen Res Inst Shenzhen Peoples R China

The multi-resolution method, e.g., the Adaptive Particle Refinement (APR) method, has been developed to increase the local particle resolution and therefore the solution quality within a pre-defined refinement zone instead of using a globally uniform resolution for Smoothed Particle Hydrodynamics (SPH). However, sometimes, the targeted zone of interest can be varying, and the corresponding topology is very complex, thus the conventional APR method is not able to track these characteristics adaptively. In this study, a novel Block-based Adaptive Particle Refinement (BAPR) method is developed, which is able to provide the necessary local refinement flexibly for any targeted characteristic, and track it adaptively. In BAPR, the so-called activation status of the block array defines the refinement regions, where the transition and activated zones are determined accordingly. A regularization method for the generated particles in the newly activated blocks is developed to render an isotropic distribution of these new particles. The proposed method has been deployed for simulating fluid-structure interaction

关键词： Smoothed particle hydrodynamics fluid-structure interaction Multi -resolution method Adaptive refinement method

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Modeling and simulation of thin-walled piezoelectric energy harvesters immersed in flow using monolithic fluid-structure interaction

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FINITE ELEMENTS IN ANALYSIS AND DESIGN 2022年 206卷

作者： Shang, Lan Hoareau, Christophe Zilian, Andreas Univ Luxembourg Dept Engn Esch Sur Alzette Luxembourg Lab Mecan Struct & Syst Couples LMSSC Conservatoire Natl arts & Metiers Cnam Paris France

A monolithic numerical scheme for fluid-structure interaction with special interest in thin-walled piezoelectric energy harvesters driven by fluid is proposed. Employing a beam/shell model for the thin-walled structure in this particular application creates a FSI problem in which an (n-1)-dimensional structure is embedded in an n dimensional fluid flow. This choice induces a strongly discontinuous pressure field along the moving fluid-solid interface. We overcome this challenge within a continuous finite element framework by a splitting-fluid-domain approach. The governing equations of the multiphysics problem are solved in a simultaneous fashion in order to reliably capture the main dynamic characteristics of the strongly-coupled system that involves a large deformation piezoelectric composite structure, an integrated electric circuit and an incompressible viscous fluid. The monolithic solution scheme is based on the weighted residuals method, with the boundary-fitted finite element method used for the discretization in space, and the generalized-? method for discretization in time. The proposed framework is evaluated against reference data of two popular FSI benchmark problems. Two additional numerical examples of flow-driven thin-walled piezoelectric energy harvesters demonstrate the feasibility of the framework to predict controlled cyclic response and limit-cycle oscillations and thus the power output in typical operational states of this class of energy harvesting devices.

关键词： fluid-structure interaction Monolithic coupling Thin-walled piezoelectric structure Energy harvester Pressure discontinuity

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A strongly coupled immersed boundary method for fluid-structure interaction that mimics the efficiency of stationary body methods

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JOURNAL OF COMPUTATIONAL PHYSICS 2022年 454卷 1页

作者： Nair, Nirmal J. Goza, Andres Univ Illinois Dept Aerosp Engn Urbana IL 61801 USA

Strongly coupled immersed boundary (IB) methods solve the nonlinear fluid and structural equations of motion simultaneously for strongly enforcing the no-slip constraint on the body. Handling this constraint requires solving several large dimensional systems that scale by the number of grid points in the flow domain even though the nonlinear constraints scale only by the small number of points used to represent the fluid-structure interface. These costly large scale operations for determining only a small number of unknowns at the interface creates a bottleneck to efficiently time-advancing strongly coupled IB methods. In this manuscript, we present a remedy for this bottleneck that is motivated by the efficient strategy employed in stationary-body IB methods while preserving the favorable stability properties of strongly coupled algorithms-we precompute a matrix that encapsulates the large dimensional system so that the prohibitive large scale operations need not be performed at every time step. This precomputation process yields a modified system of small-dimensional constraint equations that is solved at minimal computational cost while time advancing the equations. We also present a parallel implementation that scales favorably across multiple processors. The accuracy, computational efficiency and scalability of our approach are demonstrated on several two dimensional flow problems. Although the demonstration problems consist of a combination of rigid and torsionally mounted bodies, the formulation is derived in a more general setting involving an arbitrary number of rigid, torsionally mounted, and continuously deformable bodies. (C) 2021 Elsevier Inc. All rights reserved.

关键词： Immersed boundary fluid-structure interaction Strongly coupled Non-stationary bodies Parallel IB

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A Wind Tunnel Setup for fluid-structure interaction Measurements Using Optical Methods

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SENSORS 2022年第13期22卷 5014-5014页

作者： Nietiedt, Simon Wester, Tom T. B. Langidis, Apostolos Kroeger, Lars Rofallski, Robin Goering, Martina Kuhn, Martin Guelker, Gerd Luhmann, Thomas Jade Univ Appl Sci Inst Appl Photogrammetry & Geoinformat IAPG Ofener Str 16-19 D-26121 Oldenburg Germany Carl von Ossietzky Univ Oldenburg ForWind Inst Phys Kupkersweg 70 D-26129 Oldenburg Germany

The design of rotor blades is based on information about aerodynamic phenomena. An important one is fluid-structure interaction (FSI) which describes the interaction between a flexible object (rotor blade) and the surrounding fluid (wind). However, the acquisition of FSI is complex, and only a few practical concepts are known. This paper presents a measurement setup to acquire real information about the FSI of rotating wind turbines in wind tunnel experiments. The setup consists of two optical measurement systems to simultaneously record fluid (PIV system) and deformation (photogrammetry system) information in one global coordinate system. Techniques to combine both systems temporally and spatially are discussed in this paper. Furthermore, the successful application is shown by several experiments. Here, different wind conditions are applied. The experiments show that the new setup can acquire high-quality area-based information about fluid and deformation.

关键词： dynamic metrology photogrammetry PIV wind tunnel fluid-structure interaction wind turbine

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Numerical study on aeroelastic behavior of spoiler on low-rise building based on fluid-structure interaction method

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JOURNAL OF BUILDING ENGINEERING 2022年 59卷

作者： Gan, Shi Li, Gang Dong, Zhiqian Li, Hongnan Zhao, Mi Dalian Univ Technol Fac Infrastruct Engn Dalian 116024 Liaoning Peoples R China Beijing Univ Technol Key Lab Urban Secur & Disaster Engn Minist Educ Beijing 100124 Peoples R China

Technical mitigation devices have been demonstrated to be efficient for decreasing the peak and mean wind pressures on the roof systems of low-rise buildings through disrupting vortex for-mation. Previous investigations have regarded mitigation devices as rigid bodies and neglected aeroelastic behavior. However, the relatively large uplift force induces small-stiffness mitigation devices vibration and introduces a considerable aeroelastic effect. These effects might result in an increase in negative wind pressure on the building roof and the aeroelastic instability problems of mitigation devices. Therefore, the current study conducted two-way fluid-structure interaction (FSI) numerical simulation for a low-rise flat-roof building with mitigation devices (metal and polymer spoilers) to investigate the influence of the aeroelastic effect of spoiler on the wind pressure on the building roof. The large eddy simulation (LES) method and the finite element analysis (FEA) model are used to solve the flow field and the structural responses of the spoiler, respectively. The computational model and method are verified by comparing the calculation results with previous experimental results and benchmark computational tests. The dynamic response of spoiler, the flow instabilities and the wind pressure on the building roof are analyzed. The influence mechanism of the spoiler vibration on the flow field over the building, the wind pressure on the building roof and the uplift force on the spoiler were revealed considering the influencing factors, including the vibrational amplitude of spoiler and the wind direction. The results show that the aeroelastic effect of spoiler increases the negative wind pressure on the roof, and the larger the vibrational amplitude of spoiler is, the more the negative wind pressure in-creases. The negative wind pressure on the eave also increases with increasing wind direction angle. The main reason for this phenomenon is that the spoiler vibration incr

关键词： Low-rise buildings Wind pressure Mitigation device fluid-structure interaction Aeroelastic behavior

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Component quantification of aortic blood flow energy loss using computational fluid-structure interaction hemodynamics

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COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2022年 221卷 106826-106826页

作者： Qiao, Yonghui Luo, Kun Fan, Jianren Zhejiang Univ State Key Lab Clean Energy Utilizat 38 Zheda Rd Hangzhou 310027 Peoples R China Zhejiang Univ Shanghai Inst Adv Study Shanghai Peoples R China

Background and objectives: The aorta serves as the main tube of the human blood circulation system. Energy loss (EL) occurs when blood flows through the aorta and there may be a potential correlation between EL and aortic diseases. However, the components of blood flow EL are still not fully understood. This study aims to quantitatively reveal the EL components in healthy and diseased aortas. Methods: We construct an idealized healthy aorta and three idealized representative diseased aortas: aortic aneurysm, coarctation of the aorta, and aortic dissection. Computational hemodynamic studies are carried out by using the fluid-structure interaction simulation framework. Results: Four kinds of EL components: viscous friction, turbulence dissipation, wall deformation, and local lesion are firstly acquired in healthy and diseased aortas based on the high-resolution blood flow information. Viscous friction contributes most to the EL (45.69%-57.22%). EL caused by the deformation of the aortic wall ranks second (15.18%-33.12%). The proportions of turbulence dissipation and local lesion depend on individual geometric characteristics. Besides, the buffering efficiency of the healthy and diseased aorta is about 80%. Conclusions: This study quantitatively reports the components of blood flow EL in healthy and diseased aortas, the finding may provide novel insights into the pathogenesis of aortic diseases. (C) 2022 Published by Elsevier B.V.

关键词： Computational hemodynamics Energy loss Viscosity friction Turbulence dissipation fluid-structure interaction

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Coupling of the meshless finite volume particle method and the finite element method for fluid-structure interaction with thin elastic structures

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EUROPEAN JOURNAL OF MECHANICS B-fluidS 2022年 92卷 117-131页

作者： McLoone, Maryrose Quinlan, Nathan J. Natl Univ Ireland Galway Sch Engn Mech Engn Galway Ireland

A novel fluid-structure interaction (FSI) scheme is developed in this article, with the meshless finite volume particle method (FVPM) for fluid dynamics and the finite element (FE) solver FEBio for solid mechanics. Like smoothed particle hydrodynamics (SPH), FVPM is based on compactly supported particle kernels, but kernels are interpreted as a partitioning of volume, leading to a scheme with properties of both SPH and classical finite volume methods. Particle methods are advantageous for fluid modelling in FSI of highly deformable structures, as the particles can conform to the dynamic geometry of the fluid-structure interface. In FVPM, in particular, particles are rigorously truncated by boundaries, and the novel FSI scheme incorporates a sharp interface between the fluid and solid. A new method is described which avoids the possibility of unphysical communication between fluid particles separated by a thin structure. The method proposed here ensures that particles interact with the correct neighbour particles and boundaries, regardless of the particle overlap with the thin structure, allowing for particle size that can be chosen independently of structure thickness. The new method is validated for a hydrostatic water column on an elastic plate, a dam-break with elastic gate, a dam-break with a downstream elastic wall, and a 2-D model of a heart valve leaflet. In the latter two cases, the structure thickness is less than the particle diameter by a factor of up to 16. The results agree well with experimental data from the literature for fluid velocity field and solid deformation. Where quantitative data is available, the numerical results converge with decreasing particle size.(c) 2021 Elsevier Masson SAS. All rights reserved.

关键词： Finite volume particle method Particle method Meshless method fluid-structure interaction Thin structure Finite element method

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A FULL THREE-DIMENSIONAL TRANSIENT fluid-structure interaction MODEL FOR THE DYNAMIC CHARACTERISTICS PREDICTIONS OF BUMP-TYPE GAS FOIL JOURNAL BEARINGS

A FULL THREE-DIMENSIONAL TRANSIENT FLUID-STRUCTURE INTERACTI...

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ASME Turbomachinery Technical Conference and Exposition (Turbo Expo) on Collaborate, Innovate and Empower - Propulsion and Power for a Sustainable Future

作者： Li, Zhuocong Li, Zhigang Li, Jun Xi An Jiao Tong Univ Inst Turbomachinery Xian 710049 Peoples R China

ISBN: (纸本)9780791887059

Oil-lubricated bearings are used in most present-day rotating machinery due to their high load capacity. This bearing, however, requires a complicated lubrication system which significantly increases the operating cost of the equipment. Moreover, the problem of the heat generation of lubricated oil after a long time of operation cannot be ignored, especially in high-speed turbomachinery. As for oil-free turbomachinery, the gas-lubricated bearing is regarded as a revolutionary technology to support the rotor. Bump-type gas foil bearing (bump-type GFB) is one of the most widely used gas-lubricated bearings, due to its high speed, low wear, no pollution, high temperature and pressure resistance and other excellent properties. As one of the critical components in the rotor system of a rotating machinery, bump-type GFBs can provide not only the static load capacity but also the dynamic gas film response forces, significantly affecting the dynamic stability performance of the rotor system. Therefore, an accurate and efficient dynamic characteristics prediction method for bump-type GFBs is crucial for the industrial safe operation of the rotating machinery system. This paper focuses on the assessment and validation of a novel numerical method for the dynamic coefficients prediction of bump-type gas foil journal bearings (bump-type GFJBs). To predict the dynamic characteristics of bump-type GFJBs, in this paper, a novel full three-dimensional (3D) transient fluidstructure coupled numerical method was proposed, based on the finite element analysis (FEA) and the computational fluid dynamics (CFD). In order to improve computational efficiency and conform more to the bearing actual situations, a multiple-frequency elliptical-orbit rotor whirling model for arbitrary eccentric positions was proposed to define the rotor whirling motion, based on the mesh deformation techniques. The present full 3D transient CFD/FEA method was validated by the published experimental data of the dyn

关键词： bump-type gas foil journal bearings fluid-structure interaction multiple-frequency elliptical-orbit rotor whirling model eccentricity ratio dynamic characteristics

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Stroke risk evaluation for patients with atrial fibrillation: Insights from left atrial appendage with fluid-structure interaction analysis

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COMPUTERS IN BIOLOGY AND MEDICINE 2022年 148卷 105897-105897页

作者： Fang, Runxin Wang, Zidun Zhao, Xie Wang, Jun Li, Yang Zhang, Yanjuan Chen, Qiang Wang, Jiaqiu Liu, Quanjun Chen, Minglong Li, Zhiyong Southeast Univ Sch Biol Sci & Med Engn Nanjing 210096 Peoples R China Nanjing Med Univ Affiliated Hosp 1 Nanjing 210029 Peoples R China Nanjing Univ Med Sch Affiliated Hosp Nanjing Drum Tower Hosp Nanjing 210008 Peoples R China Southeast Univ Zhongda Hosp Affiliated Hosp Nanjing 210009 Peoples R China Queensland Univ Technol QUT Sch Mech Med & Proc Engn Brisbane Qld 4001 Australia

The majority of cardioembolic strokes in patients with non-valvular atrial fibrillation (NVAF) are resulted from clot formation in the left atrial appendage (LAA). Current stroke risk stratification is based on the overall risks estimated from demographic and clinical profiles but not on individual anatomy or physiology. We aim to explore the differences in LAA morphological and hemodynamic parameters by comparing patients with and without a stroke history. Thirty-nine patients with persistent NVAF were included. Of these, 17 patients without a stroke history (non-stroke group) were compared with 22 patients with a history of stroke (stroke group). Their LAA geometric models were first reconstructed, and the morphological parameters were then measured. Furthermore, their LAA hemodynamic parameters were calculated by fluid-structure interaction analysis. Moreover, particle residual rates (PRR) and blood renewal rates (BRR) analyses were also employed to characterize the thrombogenesis dynamics. The results showed that compared to the non-stroke group, the stroke group had significant smaller LAA tortuosity and LAA orifice area, and significantly lower LAA orifice velocities (0.16 +/- 0.10 vs 0.15 +/- 0.06 cm/s;p = 0.044), but higher PRR (14.58 +/- 9.43 vs 9.25 +/- 4.67;p = 0.040) and BRR (52.41 +/- 18.11 vs 38.36 +/- 24.07;p = 0.044). These LAA morphological and hemodynamic parameters may be used to assess stroke risk in patients with NVAF.

关键词： Atrial fibrillation Stroke risk Left atrial appendage Morphology Hemodynamics fluid-structure interaction

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