Jma Marco Stijnen

Finite-element-based computational methods for cardiovascular fluid-structure interaction

In this paper a combined arbitrary Lagrange-Euler fictitious domain (ALE-FD) method for fluid-structure interaction problems in cardiovascular biomechanics is derived in terms of a weighted residual finite-element formulation. For both fluid flow of blood and solid mechanics of vascular tissue, the performance of tetrahedral and hexahedral Crouzeix-Raviart elements are evaluated. Comparable convergence results are found, although for the test cases considered the hexahedral elements are more accurate. The possibilities that are offered by the ALE-FD method are illustrated by means of a simulation of valve dynamics in a simplified left ventricular flow model.

Validation of a fluid-structure interaction model of a heart valve using the dynamic mesh method in fluent

Simulations of coupled problems such as fluid–structure interaction (FSI) are becoming more and more important for engineering purposes. This is particularly true when modeling the aortic valve, where the FSI between the blood and the valve determines the valve movement and the valvular hemodynamics. Nevertheless only a few studies are focusing on the opening and closing behavior during the ejection phase (systole). In this paper, we present the validation of a FSI model using the dynamic mesh method of Fluent for the two-dimensional (2D) simulation of mechanical heart valves during the ejection phase of the cardiac cycle. The FSI model is successfully validated by comparing simulation results to experimental data obtained from in vitro studies using a CCD camera.

Computational analysis of ventricular valve–valve interaction: Influence of flow conditions

Apart from dependence on the heart muscle contractility, the pumping efficiency of the heart depends on the functioning of its valves. Valve functionality, expressed as 1 minus the ratio between regurgitant and stroke volume, is the result of the motion of the valve depending on local flow phenomena. In this work, the relation between flow conditions and valve functionality was studied by means of a parameter study of the flow and valve dynamics in a two-dimensional computational model of the left ventricle with two rigid valves. It was found that valve functionality depends strongly on the applied flow conditions as expressed by the Strouhal and the Reynolds numbers. Furthermore, it was found that the regurgitant volume can vary from beat-to-beat resulting in a non-periodic pumping efficiency of the heart. These observations are of importance to future research based on simulations of geometrically more realistic heart valve-ventricle configurations as it may not always be taken for granted that beat-to-beat variations of the pumping efficiency are small.