Predictions of Index of Hemolysis in Shear Blood Flow (Effects of Exposure Time Under Shear Stress on Prediction Accuracy)

Abstract

This paper describes the effects of shear stress and exposure time on the prediction method for the Index of Hemolysis using computational fluid dynamics (CFD) with a modified turbulence model in an orifice-pipe blood flow, which is a simple model of turbulent shear stress induced hemolysis in a high-speed rotary blood pump. Using CFD with the partially patched modified k-e model (LK (Launder-Kato) Zonal model), the results of the flow field in the orifice-pipe flow are compared with those of standard low Reynolds number k-e model at whole region (standard model: STD), and it is found that the shear stress by the LK Zonal model is predicted more precisely than that by STD model by comparing the pressure loss in the orifice and the reattachment length in the experiments. As for hemolysis, from the computational data of orifice-pipe flow, the index of hemolysis is estimated using (1) only shear stress, and (2) shear stress and exposure time, and it is found that the prediction method using only shear stress is more accurate than the method using shear stress and exposure time. From these results, the most suitable estimation method to predict hemolysis is the prediction considering only shear stress and constant exposure time using CFD in rotary blood pumps.