A THREE-DIMENSIONAL, TIME-DEPENDENT ANALYSIS OF FLOW THROUGH A BILEAFLET MECHANICAL HEART VALVE - COMPARISON OF EXPERIMENTAL AND NUMERICAL RESULTS

摘要

The how through a bileaflet mechanical heart valve during the first half of systole was predicted using computational fluid dynamics (CFD). A three-dimensional model of the geometry of the ventricle, valve, sinus and aorta was developed. Flow through the valve was assumed to be Newtonian and laminar. The peak systolic Reynolds number was 1500 based on the aortic radius and the mean aortic velocity. Flow visualisation and laser Doppler anemometry (LDA) experiments were performed and the results were compared to the CFD model. Good agreement between the LDA measurements and CFD predictions was found in the jets through the major orifices of the valve. The global how fields predicted by the CFD showed reasonable agreement with the flow visualisation. A starting vortex was shed from the valve leaflets of the CarboMedics valve and the prototype valve. As systole progressed the two major orifice jets were directed towards the aortic wall and a weaker central jet was seen in both the experimental and CFD models. Large vortices were present on either side of the central orifice jet in the sinus area of both models. The three-dimensional time-dependent CFD model was considered to give a reasonable indication of the dominant flow patterns downstream of the bileaflet heart valve and has the potential to be an extremely useful tool to analyse the different designs of existing and future bileaflet valves. [References: 17]