We are trying to do blood flow simulation on a vessel geometry model. When we try to apply Womersley boundary condition to the inlet, we meet some problems.

In Womersley boundary condition, we need to specify the property "axispoint" which should be the center of the vessel's inlet. However, we can only estimate the center of the inlet and this causes failure of simulation. Also, we are facing the same issue for the property "axisnormal". 

Does anyone have some suggestion? We are trying to change the coordinate system, but since the inlet is not a plane, it's still hard for us the accurately specify those two properties in Womersley boundary condition.

Many thanks!

Best,

Zhen