DrAmine
Ansys Employee

There is no harm if velocity field is not divergence free as the solver will cope with that scenario by adjusting the pressure field. We are simply solving transport equations for manyvariables wtihout really taken care about divergence free of the velocity field as it is not a requirement.  The pressure correction wtil compue a change in the pressure to adress sinks and sources due to velocity field.

 

You probably have interpolation errors due to transferring MRI data back and forth but again that should not be a problem for Ansys CFX (vertex centered code where the control volume are centered along the vertices of the mesh).

 

I see you contacted local support on the same question and you are getting help there.