DEVELOPMENT OF CFD METHODOLOGIES FOR ANALYSIS AND SCALING OF PULSATILE LVADS

Abstract

Background A scaled 50cc version of the PSU LVAD is under development for smaller cardiac patients. Previous efforts to scale the device have resulted in high levels of thromboembolism. It is postulated that the this is due to improper scaling resulting in a failure to maintain the hydrodynamics of the original device. Validated CFD methods will provide tools to determine the unsteady hydrodynamics occurring within the device at any geometric scale and flow condition, improving understanding of scale effect on pump performance and blood damage. Approach We’ve utilized two Navier-Stokes solvers to develop our analysis methodology. The first approach uses overset meshes to obtain detailed 3D, steady flow results with the mitral and aortic valves in the fully opened position. The second approach uses moving unstructured meshes along with transient viscosity to model valve closure. Results Comparions will be made to experimental results for the steady, 3D LVAD. The steady flowfield, shown in the figure, demonstrates valve wakes, areas of flow stagnation and recirculation. A 3D, unsteady simulation will be presented for a positive displacement type pump which models the complete transient cycle. Lastly, a discussion of the strengths/weaknesses of the two approaches towards acheiving future goals will be presented.Figure