A ventricular assist device (VAD) effectively relieves the workload from a native heart, which has been weakened by disease, and increases blood flow supplied to the body to maintain normal physiologic function. The device must be able to operate over a wide range of conditions. Designed to operate at a single, best-efficiency operating point, it must frequently perform at off-design conditions due to a fluctuating flow rate demanded by the human body and a time varying flow within the pump, due to the beating of the native heart. The design and optimization of a blood pump is a challenging and complex process. Pump design equations are used to estimate the initial dimensions of the pump regions. Computational fluid dynamics (CFD) analyses are then performed to optimize the blood flow path according to specific design criteria under steady flow conditions [1]. Dynamic flow conditions, however, are more realistic when considering in vivo implant scenario. A VAD operates under transient conditions due to the spinning of the impeller and the pulsatile inlet flow rate induced by the patient's native heart. Thus, a study exploring transient flow phenomena in the pump simulating in vivo flow conditions is important to be performed for the final model of the flow path. This study considered: (1) the interaction between the stationary and rotating blades or transient sliding interfaces; and (2) pulsatile flow or time varying boundary conditions (TVBCs). Pressure-flow correlations and the fluid forces acting on the impeller were estimated under these dynamic flow conditions.
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