Simulation of the dynamic flow field in the left ventricle of the heart during diastolic filling

Fluid-structure interaction (FSI) problems in modeling flexible structures and moving boundaries can be simulated by combining the immersed boundary (IB) method and the Lattice-Boltzmann (LB) method. In this paper, we propose an FSI model of mitral valve leaflets and the left ventricle to simulate the flow field in the left ventricle during diastolic filling based on an IB-LB coupling scheme. Changes in the flow field and mitral valve leaflets in the FSI model are simulated with the IB-LB method, in which two arc-shaped flexible fibers simulate mitral valve leaflets immersed in the flow field. At the same time, a semi-elliptical model is used to simulate the left ventricle, which is simplified as a rigid boundary. The LB method is used to solve the Newtonian flow field, and the IB method is used to simulate the deformation of the flexible fiber interacting with the flow. In this paper, we introduce the basic principles underlying the combination of the LB and the IB methods and elucidate the coupling frame and the left ventricular flow model in detail. Finally, we verify the effectiveness of the coupled models by simulating the effects of diastolic jet flow on the motion of the mitral leaflets in the simplified left ventricular flow model.