Investigating the Use of Turbulence Models for Flow Investigations in a Positive Displacement Ventricular Assist Device

Computational fluid dynamics (CFD) is applied to study the hemodynamics of flow inside a pulsatile pump left ventricular assist device (LVAD), in order to evaluate the hemolysis and thrombus formation. The positive displacement or pulsatile pump, which includes valves and a pusher plate (to mimic the natural heart), is the focus of this study. Turbulence is observed to play an important role in the accuracy of predicted levels of shear stress and strain rate, both of which are crucial in assessing the long term feasibility of the device.

In order to obtain this aim, three turbulence models have been used: a standard Reynolds stress model (RSM), the shear stress transport (SST)

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-omega, and Transition-SST, in addition to laminar flow i.e. ”no model”. An unstructured mesh was created for the simulation and the motion of the pusher plate was created via a dynamic mesh layering method. Valves were simulated in their full open position, to mimic the natural scenario. Results were allowed to reach a periodic state and were validated with available experimental data. The results indicated that the RSM gave the best agreement with the experimental data.