Turbulent Blood Flow in a Ventricular Assist Device

Application Challenge AC7-03 © copyright ERCOFTAC 2021

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Key Fluid Physics

When calculating blood flow through complex medical devices, it should always be kept in mind that blood is a non-Newtonian, multiphase fluid. However, in simulations in ventricular assist devices, blood is approximated as a Newtonian, single-phase fluid. The former is justified because blood has asymptotic viscosity under high shear rates. In the latter, a blood-analogous fluid is assumed, which has comparable density and viscosity to blood. This assumption is necessary because it is impossible with current computational technology to account for the multiphase character of blood in a VAD simulation. This is partly due to the fact that the dimensions of the blood components are much smaller than the vortex structures calculated by the simulation. Therefore, much larger computational grids than in the current literature are needed to accommodate the blood components (size order of erythrocytes ≈ 10-6 m) to be integrated in the simulation.