Blood flow in a continuous flow ventricular assist device

A numerical analysis was performed to predict the shear stresses, flow rate s, and the velocity profiles in a continuous flow ventricular assist device , the CFVAD3. The problem was modeled as a rotating disk over a stationary disk. A variety of clearances was tested for the CFVAD3 coupled with a rang e of rotational speeds and pressure gradients. Velocity fields were generat ed using solutions obtained with FLOW3D software (AEA Technology, Pittsburg h, PA, U.S.A.) Analysis of these solutions shows that the pressure differen tial effect has a stronger influence on the flow than the rotational effect of the impeller Ekman layer. The predicted shear stresses reflect these ch anges in the volume flow rates and the speeds shown in the velocity profile s. Based on the predictions of the software, the optimum clearance and rota tional speed were chosen. The conclusion is that a speed in the range of 2, 200-2,400 rpm should be chosen depending on the efficiency of the pump.