Flow mixing and fluid residence times in a model of a ventricular assist device

To provide a reliable tool for predicting the flow in a clinical sac-type v entricular assist device (VAD), a simplified model VAD was developed prior to this study for the purpose of experimental validation of computer simula tions of the time-varying flow on a moving grid. At selected locations in t he flow field, flow patterns, vortex core trajectories and velocities were compared between the numerical and physical models during one full pumping cycle. The computer simulations showed qualitatively very good agreement wi th the experiment. Quantitatively, the agreement was less favourable. In order to investigate flow mixing and to evaluate fluid residence times i n the model VAD a new tool has been developed: the numerical simulations we re extended by injecting a scalar into the flow domain. These simulations a llow investigation of the flow mixing qualitatively by visualisation and qu antification of fluid residence times. Experimental assessment of the numer ical results using dye injection proved to be favourable. The numerical res ults have been extended to include some prediction of pressure which have b een compared with experimental measurements. (C) 2001 IPEM. Published by El sevier Science Ltd. All rights reserved.