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fluid-structure interaction of patient-specific Circle of Willis with aneurysm: Investigation of hemodynamic parameters

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BIO-MEDICAL MATERIALS AND ENGINEERING 2018年第3期29卷 357-368页

作者： Jahed, Mahsa Ghalichi, Farzan Farhoudi, Mehdi Sahand Univ Technol Dept Biomed Engn Div Biomech Tabriz Iran Tabriz Univ Med Sci Neurosci Res Ctr Tabriz Iran

BACKGROUND: Circle of Willis (COW) is a network of cerebral artery which continually supplies the brain with blood. Any disturbance in this supply will result in trauma or even death. One of these damages is known as brain Aneurysm. Clinical methods for diagnosing aneurysm can only measure blood velocity;while, in order to understand the causes of these occurrences it is necessary to have information about the amount of pressure and wall shear stress, which is possible through computational models. OBJECTIVE: In this study purpose is achieving exact information of hemodynamic blood flow in COW with an aneurysm and investigation of effective factors on growth and rupture of aneurysm. METHODS: Here, realistic three-dimensional models have been produced from angiography images. Considering fluid-structure interaction have been simulated by the ANSYS. CFX software. RESULTS: Hemodynamic Studying of the COW and intra-aneurysm showed that the WSS and wall tension in the neck of aneurysms for case A are 129.5 Pa, and 12.2 kPa and for case B they are 53.3 Pa and 56.2 kPa, and more than their fundus, thus neck of aneurysm is prone to rupture. CONCLUSION: This study showed that the distribution of parameters was dependent on the geometry of the COW, and maximum values are seen in areas prone to aneurysm formation.

关键词： Aneurysm Circle of Willis computational fluid dynamic fluid-structure interaction

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fluid-structure interaction analysis of 3-D rectangular tanks by a variationally coupled BEM-FEM and comparison with test results

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EARTHQUAKE ENGINEERING & STRUCTURAL DYNAMICS 1998年第2期27卷 109-124页

作者： Koh, HM Kim, JK Park, JH Seoul Natl Univ Dept Civil Engn Seoul South Korea

A variationally coupled BEM-FEM is developed which can be used to analyse dynamic response, including free-surface sloshing motion, of 3-D rectangular liquid storage tanks subjected to horizontal ground excitation. The tank structure is modelled by the finite element method and the fluid region by the indirect boundary element method. By minimizing a single Lagrange function defined for the entire system, the governing equation with symmetric coefficient matrices is obtained. To verify the newly developed method, the analysis results are compared with the shaking-table test data of a 3-D rectangular tank model and with the solutions by the direct BEM-FEM. Analytical studies are conducted on the dynamic behaviour of 3-D rectangular tanks using the method developed. In particular, the characteristics of the sloshing response, the effect of the rigidity of adjacent walls on the dynamic response of the tanks and the orthogonal effects are investigated. (C) 1998 John Wiley & Sons, Ltd.

关键词： fluid-structure interaction rectangular tank sloshing indirect BEM-FEM

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fluid-structure interaction analysis of heat exchanger with torsional flow in the shell side

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JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY 2022年第1期36卷 479-489页

作者： Gu, Xin Wang, Guan Zhang, Qianxin Chen, Cheng Li, Ning Chen, Weijie Zhengzhou Univ Key Lab Proc Heat Transfer & Energy Saving Henan Zhengzhou 450002 Peoples R China

Based on the theory of fluid-structure interaction (FSI), the flow characteristics and mechanical properties of torsional flow heat exchanger (TFHX) and cross torsional flow heat exchanger (CTFHX) were numerically studied. The simulation results were compared with the experimental results to verify the reliability of the numerical simulation. The results show that the pressure drop of CTFHX decrease is 30.31-32.56 % lower than that of TFHX, and the heat transfer coefficient is found to lower by 16.8-18.5 %, but the comprehensive performance h/Delta P is increased by 14.8-17.9 %. There is also a higher stress around the baffle holes, and the influence of temperature load on stress is much greater than that of pressure load. Moreover, the linearization results of hazardous locations show that CTFHX has greater stress. This study provides theoretical guidance for the structural optimization and equipment maintenance of heat exchanger.

关键词： fluid-structure interaction Stress analysis Thermal hydraulic performance Torsional flow

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fluid-structure interaction of a rolling restrained body of revolution at high angles of attack

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PHYSICS OF fluidS 2017年第3期29卷 1-13页

作者： Degani, D. Ishay, M. Gottlieb, O. Technion Israel Inst Technol Dept Mech Engn IL-32000 Haifa Israel

The current work investigates numerically rolling instabilities of a free-to-roll slender rigid-body of revolution placed in a wind tunnel at a high angle of attack. The resistance to the roll moment is represented by a linear torsion spring and equivalent linear damping representing friction in the bearings of a simulated wind tunnel model. The body is subjected to a three-dimensional, compressible, laminar flow. The full Navier-Stokes equations are solved using the second-order implicit finite difference Beam-Warming scheme, adapted to a curvilinear coordinate system, whereas the coupled structural second order equation of motion for roll is solved by a fourth-order Runge-Kutta method. The body consists of a 3.5-diameter tangent ogive forebody with a 7.0-diameter long cylindrical afterbody extending aft of the nose-body junction to x/D = 10.5. We describe in detail the investigation of three angles of attack 20 degrees, 40 degrees, and 65 degrees, at a Reynolds number of 30 000 (based on body diameter) and a Mach number of 0.2. Three distinct configurations are investigated as follows: a fixed body, a free-to-roll body with a weak torsion spring, and a free-to-roll body with a strong torsion spring. For each angle of attack the free-to-roll configuration portrays a distinct and different behavior pattern, including bi-stable limit-cycle oscillations. The bifurcation structure incorporates both large and small amplitude periodic roll oscillations where the latter lose their periodicity with increasing stiffness of the restraining spring culminating with distinct quasiperiodic oscillations. We note that removal of an applied upstream disturbance for a restrained body does not change the magnitude or complexity of the oscillations or of the flow patterns along the body. Depending on structure characteristics and flow conditions even a small rolling moment coefficient at the relatively low angle of attack of 20 degrees may lead to large amplitude resonant roll oscilla

关键词： PROPERTIES of fluids fluid-structure interaction NAVIER-Stokes equations EQUATIONS in fluid mechanics

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fluid-structure interaction of a pulsatile flow with an aortic valve model: A combined experimental and numerical study

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INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2018年第4期34卷 e2945-e2945页

作者： Siguenza, Julien Pott, Desiree Mendez, Simon Sonntag, Simon J. Kaufmann, Tim A. S. Steinseifer, Ulrich Nicoud, Franck Univ Montpellier CNRS IMAG Montpellier France Rhein Westfal TH Aachen Inst Appl Med Engn Helmholtz Inst Dept Cardiovasc Engn Aachen Germany Sim&Cure Cap Gamma 1682 Rue Valsiere F-34790 Grabels France

The complex fluid-structure interaction problem associated with the flow of blood through a heart valve with flexible leaflets is investigated both experimentally and numerically. In the experimental test rig, a pulse duplicator generates a pulsatile flow through a biomimetic rigid aortic root where a model of aortic valve with polymer flexible leaflets is implanted. High-speed recordings of the leaflets motion and particle image velocimetry measurements were performed together to investigate the valve kinematics and the dynamics of the flow. Large eddy simulations of the same configuration, based on a variant of the immersed boundary method, are also presented. A massively parallel unstructured finite-volume flow solver is coupled with a finite-element solid mechanics solver to predict the fluid-structure interaction between the unsteady flow and the valve. Detailed analysis of the dynamics of opening and closure of the valve are conducted, showing a good quantitative agreement between the experiment and the simulation regarding the global behavior, in spite of some differences regarding the individual dynamics of the valve leaflets. A multicycle analysis (over more than 20 cycles) enables to characterize the generation of turbulence downstream of the valve, showing similar flow features between the experiment and the simulation. The flow transitions to turbulence after peak systole, when the flow starts to decelerate. Fluctuations are observed in the wake of the valve, with maximum amplitude observed at the commissure side of the aorta. Overall, a very promising experiment-vs-simulation comparison is shown, demonstrating the potential of the numerical method.

关键词： aortic valve fluid-structure interaction flexible leaflets immersed boundary method large eddy simulation multi-cycle analysis particle image velocimetry turbulence unstructured fluid solver

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fluid-structure interaction analysis of bioprosthetic heart valves: significance of arterial wall deformation

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COMPUTATIONAL MECHANICS 2014年第4期54卷 1055-1071页

作者： Hsu, Ming-Chen Kamensky, David Bazilevs, Yuri Sacks, Michael S. Hughes, Thomas J. R. Iowa State Univ Dept Mech Engn Ames IA 50011 USA Univ Texas Austin Inst Computat Engn & Sci Austin TX 78712 USA Univ Calif San Diego Dept Struct Engn La Jolla CA 92093 USA

We propose a framework that combines variational immersed-boundary and arbitrary Lagrangian-Eulerian methods for fluid-structure interaction (FSI) simulation of a bioprosthetic heart valve implanted in an artery that is allowed to deform in the model. We find that the variational immersed-boundary method for FSI remains robust and effective for heart valve analysis when the background fluid mesh undergoes deformations corresponding to the expansion and contraction of the elastic artery. Furthermore, the computations presented in this work show that the arterial wall deformation contributes significantly to the realism of the simulation results, leading to flow rates and valve motions that more closely resemble those observed in practice.

关键词： fluid-structure interaction Bioprosthetic heart valve Variational immersed-boundary method Arbitrary Lagrangian-Eulerian formulation Isogeometric analysis Arterial wall deformation

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fluid-structure interaction simulation of floating structures interacting with complex, large-scale ocean waves and atmospheric turbulence with application to floating offshore wind turbines

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JOURNAL OF COMPUTATIONAL PHYSICS 2018年 355卷 144-175页

作者： Calderer, Antoni Guo, Xin Shen, Lian Sotiropoulos, Fotis Univ Minnesota St Anthony Falls Lab 2 Third Ave SE Minneapolis MN 55414 USA Univ Minnesota Dept Mech Engn 111 Church St SE Minneapolis MN 55455 USA SUNY Stony Brook Coll Engn & Appl Sci Dept Civil Engn Stony Brook NY 11794 USA

We develop a numerical method for simulating coupled interactions of complex floating structures with large-scale ocean waves and atmospheric turbulence. We employ an efficient large-scale model to develop offshore wind and wave environmental conditions, which are then incorporated into a high resolution two-phase flow solver with fluid-structure interaction (FSI). The large-scale wind-wave interaction model is based on a two-fluid dynamically-coupled approach that employs a high-order spectral method for simulating the water motion and a viscous solver with undulatory boundaries for the air motion. The two-phase flow FSI solver is based on the level set method and is capable of simulating the coupled dynamic interaction of arbitrarily complex bodies with airflow and waves. The large-scale wave field solver is coupled with the near-field FSI solver with a one-way coupling approach by feeding into the latter waves via a pressure-forcing method combined with the level set method. We validate the model for both simple wave trains and three-dimensional directional waves and compare the results with experimental and theoretical solutions. Finally, we demonstrate the capabilities of the new computational framework by carrying out large-eddy simulation of a floating offshore wind turbine interacting with realistic ocean wind and waves. (c) 2017 Elsevier Inc. All rights reserved.

关键词： fluid-structure interaction Two-phase free surface flow Large-eddy simulation Level set method Wind Wave

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fluid-structure interaction simulation of calcified aortic valve stenosis

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MATHEMATICAL BIOSCIENCES AND ENGINEERING 2022年第12期19卷 13172-13192页

作者： Cai, Li Hao, Yu Ma, Pengfei Zhu, Guangyu Luo, Xiaoyu Gao, Hao Northwestern Polytech Univ Sch Math & Stat Xian 710129 Peoples R China NPU UoG Int Cooperat Lab Computat & Applicat Card Xian 710129 Peoples R China Xian Key Lab Sci Computat & Appl Stat Xian 710129 Peoples R China Xi An Jiao Tong Univ Sch Energy & Power Engn Xian 710049 Peoples R China Univ Glasgow Sch Math & Stat Glasgow G12 8QQ Lanark Scotland

Calcified aortic valve stenosis (CAVS) is caused by calcium buildup and tissue thickening that impede the blood flow from left ventricle (IN) to aorta. In recent years, CAVS has become one of the most common cardiovascular diseases. Therefore, it is necessary to study the mechanics of aortic valve (AV) caused by calcification. In this paper, based on a previous idealized AV model, the hybrid immersed boundary/finite element method (IB/FE) is used to study AV dynamics and hemodynamic performance under normal and calcified conditions. The computational CAVS model is realized by dividing the AV leaflets into a calcified region and a healthy region, and each is described by a specific constitutive equation. Our results show that calcification can significantly affect 1W dynamics. For example, the elasticity and mobility of the leaflets decrease due to calcification, leading to a smaller opening area with a high forward jet flow across the valve. The calcified valve also experiences an increase in local stress and strain. The increased loading due to AV stenosis further leads to a significant increase in left ventricular energy loss and transvalvular pressure gradients. The model predicted hemodynamic parameters are in general consistent with the risk classification of AV stenosis in the clinic. Therefore, mathematical models of AV with calcification have the potential to deepen our understanding of AV stenosis-induced ventricular dysfunction and facilitate the development of computational engineering-assisted medical diagnosis in AV related diseases.

关键词： fluid-structure interaction aortic valve calcification hybrid immersed boundary/finite element method

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fluid-structure interaction of a large ice sheet in waves

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OCEAN ENGINEERING 2019年 182卷 102-111页

作者： Huang, Luofeng Ren, Kang Li, Minghao Tukovic, Zeljko Cardiff, Philip Thomas, Giles UCL Dept Mech Engn London England Chalmers Univ Technol Dept Mech & Maritime Sci Gothenburg Sweden Univ Zagreb Fac Mech Engn & Naval Architecture Zagreb Croatia Univ Coll Dublin Sch Mech & Mat Engn Dublin Ireland

With global warming, the ice-covered areas in the Arctic are being transformed into open water. This provides increased impetuses for extensive maritime activities and attracts research interests in sea ice modelling. In the polar region, ice sheets can be several kilometres long and subjected to the effects of ocean waves. As its thickness to length ratio is very small, the wave response of such a large ice sheet, known as its hydroelastic response, is dominated by an elastic deformation rather than rigid body motions. In the past 25 years, sea ice hydroelasticity has been widely studied by theoretical models;however, recent experiments indicate that the ideal assumptions used for these theoretical models can cause considerable inaccuracies. This work proposes a numerical approach based on OpenFOAM to simulate the hydroelastic wave-ice interaction, with the Navier-Stokes equations describing the fluid domain, the St. Venant Kirchhoff solid model governing the ice deformation and a coupling scheme to achieve the fluid-structure interaction. Following validation against experiments, the proposed model has been shown capable of capturing phenomena that have not been included in current theoretical models. In particular, the developed model shows the capability to predict overwash, which is a ubiquitous polar phenomenon reported to be a key gap. The present model has the potential to be used to study wave-ice behaviours and the coupled wave-ice effect on marine structures.

关键词： fluid-structure interaction Hydroelasticity Sea ice Ocean surface wave Overwash OpenFOAM

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fluid-structure interaction analysis of buoyancy-driven fluid and heat transfer through an enclosure with a flexible thin partition

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INTERNATIONAL JOURNAL OF NUMERICAL METHODS FOR HEAT & fluid FLOW 2018年第9期28卷 2072-2088页

作者： Zargartalebi, H. Ghalambaz, M. Chamkha, A. Pop, Ioan Nezhad, Amir Sanati Univ Calgary Ctr Bioengn Res & Educ Dept Mech & Mfg Engn Calgary AB Canada Islamic Azad Univ Dept Mech Engn Dezful Iran Prince Mohammad Bin Fahd Univ Dept Mech Engn Al Khobar Saudi Arabia Amer Univ Ras Al Khaimah RAK Res & Innovat Ctr Ras Al Khaymah U Arab Emirates Babes Bolyai Univ Dept Appl Math Cluj Napoca Romania

Purpose A numerical model of an unsteady laminar free convection flow and heat transfer is studied in a cavity that comprises a vertical flexible thin partition. Design/methodology/approach The left and right vertical boundaries are isothermal, while the horizontal boundaries are insulated. Moreover, the thin partition, placed in the geometric centerline of the enclosure, is considered to be hyper elastic and diathermal. Galerkin finite-element methods, the system of partial differential equations along with the appropriate boundary conditions are transformed to a weak form through the fluid-structure interaction and solved numerically. Findings The heat transfer characteristics of the enclosure with rigid and flexible partitions are compared. The effect of Rayleigh number and Young's modulus on the maximum nondimensional stress and final deformed shape of the membrane is addressed. Originality/value Incorporation of vertical thin flexible membrane in middle of a cavity has numerous industrial applications, and it could noticeably affect the heat and mass transfer in the enclosure.

关键词： fluid-structure interaction Flexible thin partition Lagrangian-Eulerian formulation Unsteady free convection

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