3D Fluid-Structure Interaction Simulation of Aortic Valves Using a Unified Continuum ALE FEM Model

Abstract

Due to advances in medical imaging, computational fluid dynamics algorithms and high performance computing, computer simulation is developing into an important tool for understanding the relationship between cardiovascular diseases and intraventricular blood flow. The field of cardiac flow simulation is challenging and highly interdisciplinary. We apply a computational framework for automated solutions of partial differential equations using Finite Element Methods where any mathematical description directly can be translated to code. This allows us to develop a cardiac model where specific properties of the heart such as fluid-structure interaction of the aortic valve can be added in a modular way without extensive efforts. In previous work, we simulated the blood flow in the left ventricle of the heart. In this paper, we extend this model by placing prototypes of both a native and a mechanical aortic valve in the outflow region of the left ventricle. Numerical simulation of the blood flow in the vicinity of the valve offers the possibility to improve the treatment of aortic valve diseases as aortic stenosis (narrowing of the valve opening) or regurgitation (leaking) and to optimize the design of prosthetic heart valves in a controlled and specific way. The fluid-structure interaction and contact problem are formulated in a unified continuum model using the conservation laws for mass and momentum and a phase function. The discretization is based on an Arbitrary Lagrangian-Eulerian space-time finite element method with streamline diffusion stabilization, and it is implemented in the open source software Unicorn which shows near optimal scaling up to thousands of cores. Computational results are presented to demonstrate the capability of our framework.

Augmented resistive immersed surfaces valve model for the simulation of cardiac hemodynamics with isovolumetric phases

“…The earliest three-dimensional models and simulations of cardiac valves FSI date back to the beginning of this century, [7][8][9][10] and since then, the topic has seen a surge of interest in the literature. [11][12][13][14][15][16][17] In most of these studies, computational cost is recognized as a key difficulty, often related to the efficiency of the FSI coupling strategy, the treatment of solid contact, or the (fitted or unfitted) nature of the spatial discretization. Unfitted mesh methods, such as the immersed boundary 10,11,18 and the fictitious domain 7,8,13 methods, are generally preferred to the more traditional fitted mesh approaches 16,17 (based on an arbitrary Lagrangian-Eulerian [ALE] formalism).…”

Fluid–Structure Interaction Models of Bioprosthetic Heart Valve Dynamics in an Experimental Pulse Duplicator

“…Accounting for coupling between the flexible valve leaflets and the fluid flow is crucial in studying the e↵ect of vortices in the aortic sinuses, predicting fluid-induced shear stress on the leaflets, and assessing valve performance by quantifying the valve orifice area and regurgitation [9]. A widely used approach to simulating cardiovascular FSI is the arbitrary Lagrangian-Eulerian (ALE) method [10,11], which uses body-conforming meshes for the fluid and solid. ALE methods have realized limited success in simulating the dynamics of heart valves to date, however, because of the substantial challenges posed by dynamically generating geometrically conforming discretizations of thin structures that undergo substantial motion [10,11].…”

Computational investigation of hemodynamics in hardshell venous reservoirs: A comparative study

“…Computational investigation of the blood flow in artificial organs and biomedical devices such as heart pumps in various designs has equally attracted attention . A further field where CFD approaches have been extensively utilized comprises design engineering and performance monitoring of heart valves …”

“…[12][13][14][15] A further field where CFD approaches have been extensively utilized comprises design engineering and performance monitoring of heart valves. [16][17][18][19] One of the early CFD analyses of oxygenators (including the membrane and the hardshell reservoir) is due to Gage et al, 20 who investigated a commercial membrane oxygenator computationally and experimentally, with emphasis on the pressure drop. A Newtonian behavior for the blood was assumed, along with the assumption of a laminar flow.…”