Fluid–structure interaction models of the mitral valve: function in normal and pathological states

Successful mitral valve repair is dependent upon a full understanding of normal and abnormal mitral valve anatomy and function. Computational analysis is one such method that can be applied to simulate mitral valve function in order to analyse the roles of individual components and evaluate proposed surgical repair. We developed the first three-dimensional finite element computer model of the mitral valve including leaflets and chordae tendineae; however, one critical aspect that has been missing until the last few years was the evaluation of fluid flow, as coupled to the function of the mitral valve structure. We present here our latest results for normal function and specific pathological changes using a fluid–structure interaction model. Normal valve function was first assessed, followed by pathological material changes in collagen fibre volume fraction, fibre stiffness, fibre splay and isotropic stiffness. Leaflet and chordal stress and strain and papillary muscle force were determined. In addition, transmitral flow, time to leaflet closure and heart valve sound were assessed. Model predictions in the normal state agreed well with a wide range of available in vivo and in vitro data. Further, pathological material changes that preserved the anisotropy of the valve leaflets were found to preserve valve function. By contrast, material changes that altered the anisotropy of the valve were found to profoundly alter valve function. The addition of blood flow and an experimentally driven microstructural description of mitral tissue represent significant advances in computational studies of the mitral valve, which allow further insight to be gained. This work is another building block in the foundation of a computational framework to aid in the refinement and development of a truly non-invasive diagnostic evaluation of the mitral valve. Ultimately, it represents the basis for simulation of surgical repair of pathological valves in a clinical and educational setting.

Download Full-text

Fluid-Structure Interaction Simulation of the Edge-to-Edge Repair of the Mitral Valve in Functional and Degenerative States

ASME 2012 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2012-80288 ◽

2012 ◽

Author(s):

K. D. Lau ◽

G. Burriesci ◽

V. Díaz-Zuccarini

Keyword(s):

Mitral Valve ◽

Fluid Structure Interaction ◽

Mitral Valve Regurgitation ◽

Fluid Structure ◽

Explicit Finite Element ◽

Structure Interaction ◽

Modelling Techniques ◽

Induced Stresses ◽

Annular Dilation ◽

Ventricular Filling

The most common dysfunction of the mitral valve (MV) is mitral valve regurgitation (MVR) which accounts for approximately 70% of native MV dysfunction [1]. During closure, abnormal amounts of retrograde flow enter the left atrium altering ventricular haemodynamics, an issue which can lead to cardiac related pathologies. MVR is caused by a variety of different mechanisms which are either degenerative (myxomatous degeneration) or functional (annular dilation or papillary muscle displacement) [2]. Correction of MVR is performed by repairing existing valve anatomy or replacement with a prosthetic substitute, however repair is preferred as mortality rates are reduced (2.0% against 6.1% for replacement) along with other valve related complications [3]. A common and popular method of repair is the edge-to-edge repair (ETER), which aims to correct MVR by surgically connecting the regurgitant region through reducing the inter-leaflet distance. Although MV function is improved in systole, induced stresses are significantly increased in diastole where the MV is typically in a low state of stress. In order to assess the effect of this technique in diastole, where the dynamics of both the MV and ventricular filling are disrupted it is required to use fluid-structure interaction (FSI) modelling techniques. Here a FSI model of the of the MV has been described, using this model the resulting induced stresses from the ETER in both functional and degenerative states of the MV have been simulated and assessed using the explicit finite element code LS-DYNA.

Download Full-text

Free Vibration and Thermal Fluid Structure Interaction Simulation of Functionally Graded Pipe by Modeling As Layered Structure

JSME 2020 Conference on Leading Edge Manufacturing/Materials and Processing ◽

10.1115/lemp2020-8506 ◽

2020 ◽

Author(s):

Ziyi Su ◽

Kazuaki Inaba ◽

Amit Karmakar ◽

Apurba Das

Keyword(s):

Free Vibration ◽

Layered Structure ◽

Volume Fraction ◽

Fluid Structure Interaction ◽

Functionally Graded ◽

Fluid Structure ◽

Structure Interaction ◽

Layered Model ◽

Piping Systems ◽

Complex Phenomena

Abstract Functionally graded materials (FGMs) are advanced class of composite materials which can be used as the thermal barrier to protect inner components from the outside high temperature environment. In FGMs, the volume fraction of each constituent can be tailored made across the thickness for desired applications. In this work, the simulation of FGMs in pipes is considered. Despite the wide application of pipes in machinery, those pipes would suffer from many safety problems, such as thermal stress, cavitation, fracture etc. Application of FGMs to the piping systems could lead to some new solutions accounting for safety measures and higher service life. However, the complex phenomena within the fluid structure interaction are hard to describe with the theoretical solution. The visualization of results from simulation will be helpful in understanding the distribution of kinds of physical quantities within the concerned model. For the simulation, FGMs are modeled as the layered structure in the standard finite element method (FEM) package based on FGM constituent law. The free vibration of the FG pipe is simulated and the accuracy of layered model is verified by numerical calculations. Further, based on the layered model, conjugate heat transfer simulations in a heat exchanger with FGMs are conducted.

Download Full-text

Mitral valve dynamics in structural and fluid–structure interaction models

Medical Engineering & Physics ◽

10.1016/j.medengphy.2010.07.008 ◽

2010 ◽

Vol 32 (9) ◽

pp. 1057-1064 ◽

Cited By ~ 67

Author(s):

K.D. Lau ◽

V. Diaz ◽

P. Scambler ◽

G. Burriesci

Keyword(s):

Mitral Valve ◽

Fluid Structure Interaction ◽

Fluid Structure ◽

Interaction Models ◽

Structure Interaction ◽

Valve Dynamics

Download Full-text

Image-based fluid–structure interaction model of the human mitral valve

Computers & Fluids ◽

10.1016/j.compfluid.2012.10.025 ◽

2013 ◽

Vol 71 ◽

pp. 417-425 ◽

Cited By ~ 31

Author(s):

Xingshuang Ma ◽

Hao Gao ◽

Boyce E. Griffith ◽

Colin Berry ◽

Xiaoyu Luo

Keyword(s):

Mitral Valve ◽

Fluid Structure Interaction ◽

Interaction Model ◽

Fluid Structure ◽

Structure Interaction

Download Full-text

Analysis of Gas-Liquid Cylindrical Cyclone Separator With Inlet Modifications Using Fluid–Structure Interaction

Journal of Energy Resources Technology ◽

10.1115/1.4044762 ◽

2019 ◽

Vol 142 (4) ◽

Author(s):

Srinivas Swaroop Kolla ◽

Ram S. Mohan ◽

Ovadia Shoham

Keyword(s):

Case Studies ◽

Slug Flow ◽

Structural Integrity ◽

Fluid Structure Interaction ◽

Attractive Alternative ◽

Inlet Section ◽

Fluid Structure ◽

Structure Interaction ◽

Wide Range ◽

Cylindrical Cyclone

Abstract The gas-liquid cylindrical cyclone (GLCC©, The University of Tulsa, 1994) is a simple, compact, and low-cost separator, which provides an economically attractive alternative to conventional gravity-based separators over a wide range of applications. The GLCC© inlet section design is a key parameter, which is crucial for its performance and proper operation. An in-depth evaluation of specific design modifications and their effect on safety and structural robustness are carried out in this study using finite element analysis (FEA). Fluid–structure interaction (FSI) analysis is also carried out using the results of computational fluid dynamics (CFD) aimed at investigating the effect of fluid flow on the inlet section structural integrity. The selected design modifications are based on feasibility of GLCC© manufacturing and assembly for field applications. Different case studies incorporating sustained GLCC© internal pressure, dead weight loading, forces generated because of slug flow and high temperatures are analyzed and presented in this paper. The concept of holes cut out in baffle has been effective with no stresses or deformation in the baffle area. FSI simulation of slug flow has proved that FEA direct loading case studies are far more conservative.

Download Full-text

FLUID STRUCTURE INTERACTION SIMULATION TO IMPROVE EVALUATION OF MITRAL VALVE REPAIR

Journal of the American College of Cardiology ◽

10.1016/s0735-1097(18)32518-x ◽

2018 ◽

Vol 71 (11) ◽

pp. A1977

Author(s):

Vijay Govindarajan ◽

Hyunggun Kim ◽

Krishnan Chandran ◽

David McPherson

Keyword(s):

Mitral Valve ◽

Mitral Valve Repair ◽

Fluid Structure Interaction ◽

Valve Repair ◽

Fluid Structure ◽

Structure Interaction ◽

Interaction Simulation

Download Full-text

Fluid - Structure Interaction Modeling of Elastohydrodynamically Lubricated Line Contacts

Journal of Tribology ◽

10.1115/1.4049260 ◽

2020 ◽

pp. 1-39

Author(s):

Kushagra Singh ◽

Farshid Sadeghi ◽

Thomas Russell ◽

Steven J. Lorenz ◽

Wyatt L. Peterson ◽

...

Keyword(s):

Reynolds Equation ◽

Stokes Equations ◽

Flow Behavior ◽

Fluid Structure Interaction ◽

Simulation Software ◽

Fluid Structure ◽

Structure Interaction ◽

Elastic Plastic ◽

Wide Range ◽

Line Contacts

Abstract This paper presents a partitioned fluid-structure interaction (FSI) solver to model elastohydrodynamic lubrication (EHL) of line contacts. The FSI model was constructed using the multiphysics simulation software ANSYS wherein an iterative implicit coupling scheme is implemented to facilitate the interaction between fluid and solid components. The model employs a finite volume method (FVM) based computational fluid dynamics (CFD) solver to determine the lubricant flow behavior using the Navier-Stokes equations. Additionally, the finite element method (FEM) is utilized to model the structural response of the solid. Fluid cavitation, compressibility, non-Newtonian lubricant rheology, load balance algorithm and dynamic meshing were incorporated in the FSI model. The pressure and film thickness results obtained from the model are presented for a wide range of loads, speeds, slide to roll ratios (SRR), surface dent, material properties (elastic plastic), etc. The model presents a detailed understanding of EHL contacts by removing any assumptions relative to the Reynolds equation. It provides the (i) two-dimensional variation of pressure, velocity, viscosity etc. in the fluid, and (ii) stress, elastic/plastic strain in the solid, simultaneously. The FSI model is robust, easy to implement and computationally efficient. It provides an effective approach to solve sophisticated EHL problems. The FSI model was used to investigate the effects of surface dents, plasticity and material inclusions under heavily loaded lubricated line contacts as can be found in gears and rolling element bearings. The results from the model exhibit excellent corroboration with published results based on the Reynolds equation solvers.

Download Full-text

Comparison of Fluid Structure Interaction Capabilities in Finite Volume and Finite Element Based Codes

Volume 12: Mechanics of Solids, Structures, and Fluids ◽

10.1115/imece2020-23082 ◽

2020 ◽

Author(s):

Qiyue Lu ◽

Alfonso Santiago ◽

Seid Koric ◽

Paula Cordoba

Keyword(s):

Finite Element ◽

Finite Volume ◽

Fluid Structure Interaction ◽

Arbitrary Lagrangian Eulerian ◽

Fluid Structure ◽

Ale Method ◽

Structure Interaction ◽

Commercial Code ◽

Wide Range ◽

Volume Method

Abstract Fluid-Structure Interaction (FSI) simulations have applications to a wide range of engineering areas. One popular technique to solve FSI problems is the Arbitrary Lagrangian-Eulerian (ALE) method. Both academic and industry communities developed codes to implement the ALE method. One of them is Alya, a Finite Element Method (FEM) based code developed in Barcelona Supercomputing Center (BSC). By analyzing the application on a simplified artery case and compared to another commercial code, which is Finite Volume Method (FVM) based, this paper discusses the mathematical background of the solver for domains, and carries out verification work on Alya’s FSI capability. The results show that while both codes provide comparable FSI results, Alya has exhibited better robustness due to its Subgrid Scale (SGS) technique for stabilization of convective term and the subsequent numerical treatments. Thus this code opens the door for more extensive use of higher fidelity finite element based FSI methods in future.

Download Full-text