NUMERICAL AND EXPERIMENTAL FLUID-STRUCTURE INTERACTION MODELS OF A PROSTHETIC AORTIC VALVE

Abstract

Geometrical models are the same in both numerical and experimental simulations. They consist of a rigid straight tube at the entrance (resp. at the outflow) simulating the left ventricle outflow tract (resp. the aorta). The bileaflet valve is a 27 mm St Jude valve. The sinuses of Valsalva are supposed axisymmetrical. At the entrance, a long enough tube ensures a fully developed flow. The inlet conditions are then velocity profiles defined from the Womersley solution [Womersley, 1955]. The shape of the flow rate is physiological. The outlet conditions are considered as free conditions. The fluid is assumed to be Newtonian and viscous as the blood ( =4.0 cP, =1130 kg/m). The flow is 3D, laminar and unsteady. These boundary and hydrodynamic conditions are the same in both numerical and experimental simulations. The numerical simulation is realized with the commercial software Fluent (Fluent Inc, Lebanon, USA). FSI is taken into account through pressure and viscous forces on each leaflet. The resultant moment is then calculated. A sub iteration loop [Dumont, 2004] is managed in each time step to ensure a strong coupling between the fluid and the structure. The experimental simulation is conducted in a rigid Plexiglas model inserted in a circulatory mock loop model. Pressure and flow rate measurements are recorded. The fluid is seeded with nylon particles. PIV measurements are realized in two perpendicular plans, during the systolic ejection time.