Computational Modelling of Bileaflet Mechanical Valves Using Fluid-Structure Interaction Approach

This study presents numerical simulations of a minimally constrained mechanical valve model using a fully coupled fluid-structure interaction method with COMSOL Multiphysics, a fmite-element-based software package. The model applies a physiological pulsatile pressure gradient across an aortic valve with an approximately symmetric aortic root. The complex hinge from the exact model is simplified with a pin joint and weak constraints to control the designated valve leaflet positions. The arbitrary Lagrangian-Eulerian method is applied in order to accommodate large mesh displacements due to leaflet motion. Constant material properties are applied to both the fluid and structure with the assumption that the flow is Newtonian and turbulent. The valve leaflet positions and flow patterns are verified against the results from literature. Hemodynamic performance in terms of flow velocity and shear stress is investigated. The maximum von Mises stress for each valve leaflet is calculated. Moreover, a simulation on a defective mechanical valve is conducted and hemodynamic and structural analyses are performed. It is found that vortices were generated with higher blood velocity passing through the unconstrained leaflet, which may lead to diagnostic confusion.