inlet condition for 3D simulation
 

I am conducting a drag coefficient simulation for a cylinder in three dimensions.

I am referencing a paper for the simulation.

Specifically, I am applying potential flow conditions at the inlet.

Is applying a condition at the inlet where the flow has a specific velocity vertically from the surface different from the usual practice of having a velocity perpendicular to the inlet surface?

Considering the inlet condition where the velocity is perpendicular to the surface, wouldn't there be some nonzero rotation since the flow is not purely potential?

Even if they are different, would it significantly impact the Large Eddy Simulation (LES)?

I am calculating the drag coefficient from turbulent flows.

Thank you. :D