서강대학교

초록/요약

For medical devices with blood flows, it is important to analyze and reduce degradation of the red blood cells, known as hemolysis. Previous studies identified that the blood shear stress is the most important factor for hemolysis in medical devices such as blood pumps. In the devices with turbulent flows, the regions with a high shear stress are concentrated near the wall. In order to predict hemolysis numerically, this results in a very fine mesh and expensive computational cost for accurate prediction. In engineering analysis of turbulent flows, turbulent wall models are widely used to relax the grid requirements. However, there is no turbulent wall model proposed for hemolysis yet, which is the motivation of the present study. In order to decrease the uncertainty of the hemolysis prediction in medical devices, the blood damage index (BDI) is calculated using a hybrid approach based on two divided regions. In the near-wall region, an analytic approach using a modeled velocity profile is employed to reduce the numerical errors from a large velocity derivative in a coarse grid resolution. We use the Van Driest law from turbulence theory as the model for the mean velocity profile. In a region far from the wall, a regular numerical discretization is applied. The effectiveness of the proposed turbulent wall model for hemolysis is assessed for turbulent flows inside medical devices such as a cannula and centrifugal blood pumps. Moreover, we compared the previous experiment results to our predicted results; the utility of turbulent wall model for hemolysis was verified. The predicted BDI results present that the proposed turbulent wall model shows a significantly improved grid convergence and decreased simulation uncertainty compared to the fully discrete approach used so far.