Three-dimensional study of the effect of two leaflet opening angles on the time-dependent flow through a bileaflet mechanical heart valve

A three-dimensional (3-D), time-dependent computational fluid dynamics (CFD) model was used to investigate the effect of leaflet opening angle on the flow through a fully open bileaflet heart valve up to peak systole. A laminar flow model of a Newtonian fluid was used, and the peak systolic. Reynolds number was 1500, based on the aortic radius and the average velocity at peak systole. This resulted in a Reynolds number of 5800, based on the aortic radius and the local maximum velocity. The flow fields through and downstream of the bileaflet valves were complex, with strong time-dependent 3-D vortices being found in planes parallel and perpendicular to the leaflets. The parametric study of the effect of leaflet opening angle showed that, as the leaflet opening angle increased from 78 degrees to 85 degrees, the flow downstream of the valve leaflets became more centralized, and the wake downstream of the leaflet decreased in size. However, as the opening angle increased from 78 degrees to 85 degrees, the maximum shear rate and the maximum velocity increased, suggesting that the design of the central orifice geometry was also an important consideration.