Turbulent Blood Flow in a Ventricular Assist Device

Application Challenge AC7-03 © copyright ERCOFTAC 2021

Evaluation

Influence of the Discretization Error with URANS

Fig.2.2 Test rig as CAD model. The numerised components are explained in the text.

Figure 5.1. shows the discretization error uncertainties of the pressure headvia the VADs impeller and the whole pump. The error intervals of total pressure heads were up to 4.8% for the finest grid. From an engineering point of view, these uncertainties are in an acceptable range for the VAD design. In addition, the uncertainty for the pressure head for the whole VAD (4.8%) is higher than for the impeller alone (1.7%). The reason for this is that turbulent phenomena, e.g. detachment in the outlet guide vane, affect the pressure increase via the whole pump. Those effects may have a significant mesh sensitivity and thus affect the uncertainty of the pressure head for the entire VAD. Furthermore, the relatively small uncertainties for the pressure heads suggest that the grid resolution of UR-7 is fine enough to guarantee a grid-independent solution and no further grid refinement seems to be required for these results.