Evaluation of CFD based hemolysis prediction methods

Accurate quantitative evaluation of shear stress-related hemolysis (destruction of red blood cells) could be used to improve blood handling devices, including left ventricular assist devices (LVAD). Computational Fluid Dynamics (CFD) predicts the fluid dynamics of complex pump geometry and has been used to track the shear stress history of red blood cells as they travel through these devices. Several models that predict the relationship between hemolysis, shear stress and exposure time have been used to evaluate the hemolysis in the pumps. However, the prediction accuracy has not reached the satisfactory level. The goal of my thesis is to investigate the application of CFD in determining hemolysis using different hemolysis prediction methods. • This approach is two-fold. First it is done on a simplified geometry designed to produce known and controllable shear stresses. This device is known as the mag-lev shearing device and was designed using CFD in order to study erythrocyte damage in terms of the effects of shear stress. This mathematical solution for annular shearing device will be used to verify computational data. • Secondly, I applied the same methods to the LEV-VAD pump, currently under development at RIT. The grid independent mesh was obtained for RIT axial pump and was utilized for further studies. In Characteristic curve (Pressure vs. Flow), the experimental pressure rise data was compared with the pressure difference data from CFD simulation of the RIT mini pump. • Hemolysis was estimated for both geometries using four different hemolysis analysis methods, referred to as: Threshold Value, Mass-Weighted Average, Eulerian and Lagrangian approaches. The pump numerical hemolysis predictions are compared with the previous in vitro hemolysis data using bovine blood. The numerical simulation of flow field for mag-lev shearing device was compared with the analytical solution of the fluid dynamics inside the gap regions of the device. In the future, the mag-lev shearing device will be used with animal and human blood to empirically evaluate the hemolysis and this empirical data may be used to validate the numerical methods presented here