Numerical solution for blood flow in a centrifugal ventricular assist device

A very small centrifugal pump, fully supported by magnetic bearings, is bei ng developed for use as a ventricular assist device to be implanted in huma ns. In this paper, we apply computational fluid dynamics to model the blood flow to aid in the design of the ventricular assist device. The flow of bl ood through the pump has been modeled using computational fluid dynamics (C FD) software that is commercially available from AEA Technology, UK. The fl ow regions modeled in Version 3 of the Continuous Flow Ventricular Assist D evice (CF3) are the fully shrouded four bladed impeller and the two clearan ce regions around the impeller that are bounded by the pump hub and shroud. This paper describes the geometry and computational grids developed for th e flow regions, and the equations of motion for the blood flow are develope d. The overall numerically-evaluated flow rates and head rise have similar trends to the flow parameters experimentally measured, indicating that futu re pump designs can be effectively modeled numerically before being constru cted and tested. Numerical solutions are presented and compared with experi mentally-obtained overall pump performance results. These solutions are use d to predict shear stress levels to be experienced by the blood flowing thr ough the pump, and if is predicted that hemolysis will be insignificant. Th e solutions also indicate no regions of flow stagnation that can be a sourc e of thrombosis in pumps. The calculations provide a viable design method t o achieve improved efficiency in future versions of this pump.