Mesh Sensitivity Analysis for Quantitative Shear Stress Assessment in Blood Pumps Using Computational Fluid Dynamics

This study investigated the necessary mesh refinement to quantify shear stress for two selected, meshing sensitive hotspots within a rotary centrifugal blood pump (the blade leading edge and tip clearance gap). The shear stress in these regions is elevated due to presence of stagnation points and the flow around a sharp edge. The nondimensional mesh characteristic number y+, which is known in the context of turbulence modeling, underestimated the maximum wall shear stress by 60% on average with the recommended value of 1, but was found to be exact below 0.1. To evaluate the meshing related error on the numerical hemolysis prediction, three-dimensional simulations of a generic centrifugal pump were performed with mesh sizes from 3  × 106 to 30  × 106 elements. The respective hemolysis was calculated using an Eulerian scalar transport model. Mesh insensitivity was found below a maximum y+ of 0.2 necessitating 18  × 106 mesh elements. A meshing related error of up to 25% was found for the coarser meshes. Further investigations need to address: (1) the transferability to other geometries and (2) potential adaptions on blood damage estimation models to allow better quantitative predictions.
Source: Journal of Biomechanical Engineering - Category: Biomedical Engineering Source Type: research