Fluid-structure Interaction Simulation of Bileaflet and Monoleaflet Mechanical Heart Valve Flow Dynamics

In this study, opening and closing behavior of monoleaflet and bileaflet prosthetic heart valves was simulated using 2D and 3D Fluid Structure Interaction (FSI) models. The FSI models were based on the arbitrary Lagrangian-Eulerian (ALE) method for moving boundaries. Leaflet and diaphragm motions were described by means of user-defined functions following the experimental setup in a previous study. The hemodynamic performance of monoleaflet valves at the opening angle of 45, 60, 75, 80, and 85 was compared and results from this study demonstrated that the optimal opening angle should fall between 75 and 80. As the opening angle further increased, even though the calculated flow parameters continued to improve, the large angle could prevent the valve to close properly, which might lead to the failure of the heart valve. Furthermore, the hemodynamic performance of bileaflet and monoleaflet heart valves following the design of St. Jude bileaflet valve with 85 of opening angle and Bjork-Shiley monoleaflet valve with 75 of opening angle was compared. Results demonstrated that the flow in the monoleaflet valve design had a lower maximum velocity compared to the bileaflet design during both opening and closing phases which resulted in lower chance for flow to transition to turbulence. The mean pressure gradients across the monoleaflet and bileaflet valves were similar and resulted in an analogous EOA for these valves. According to the results of this study, the bileaflet valve had higher chance of developing cavitation bubbles during the valve closure because of higher pressure drops across the valve.Mechanical & Aerospace Engineerin