Negative drag coeff. - Shallowly submerged 3D hydrofoil
 

I have just been through a typical run of 2D simulations with different AOAs to verify the Cl/Cd relations for a specific NACA profile, 4412.

But my 3D simulations fail to get sensible coefficient results. What would be the desired meshing technique for this scenario? I am using an automated mesh procedure. Are my physics models okay?

........... cause of problem: Inlet boundaries (top, bottom and actual inlet plane) from the 2D optimal AOA test run, were still configured for the 3D setup.

Kind of knew about it, but velocity direction was set up in straight X. Hmmm, be careful, there are overlapping parameters in Star ;-(