Computational fluid dynamics analysis of a centrifugal blood pump with washout holes

The authors studied avoidance of coagulation occurrence using computational fluid dynamics (CFD) analysis from the fluid dynamical point of view. Conc erning centrifugal pumps, blood coagulation sometimes occurs at the region behind the impeller where the flow is generally stagnant. Therefore, we con ducted a thorough study with the specimen pump with and without washout hol es, mocking up the Nikkiso HPM-15. As the result, the model with washout ho les indicated that the fluid rotates rapidly at the vicinity of the shaft a nd generates washout effects near the stationary rear casing. On the other hand, the model without washout holes showed that fluid cannot be quickly s hipped out of the area behind the impeller and rotates mildly around the sh aft. To clarify the moving relations between the impeller and the fluid, va lidation studies by comparing the results of CFD analysis and flow visualiz ation experiments are ongoing; thus far, the studies show that CFD results are similar to the results from flow visualization experiments.