Fluid-structure interaction analysis of aortic valve dynamics: effects of aspect ratio.

The geometric configuration of prosthetic aortic valve is a key determinant of its mechanical response and associated hemodynamics during the cardiac cycle. In this work, high-fidelity fluid-structure interaction (FSI) analysis is conducted to provide physical insight into the effects of geometry on valve design. We integrate the data from the Doppler experiments and the Windkessel model for the inlet velocity and outlet pressure conditions, respectively. The arbitrary Lagrangian-Eulerian method is employed to address the two-way interaction between hyperelastic leaflets undergoing periodic large deformation and the surrounding blood flow. The effects of leaflet aspect ratio (AR) and blood non-Newtonian properties on mechanical performance are systematically investigated. The FSI analysis shows that increasing AR elevates von Mises stress, wall shear stress, blood velocity magnitude, transvalvular pressure gradient and regurgitation fraction (RF), while reducing geometric orifice area (GOA). These trends are opposite to the results from pure structural mechanical analysis. As AR increases from 0.86 to 1.26, the maximum von Mises stress increases by 58.66%, whereas GOA decreases by 71.54%. For the AR = 1.26 valve, the jet deviates from the centerline toward the lower vessel wall during peak systole and the subsequent deceleration phase, resulting in asymmetric deformation.