separation region in corner flows submitted to curvature effects

Stephane

I am a Ph.D. student working on 3D Compressor flows in Jet engines. But I think my problem is of general nature anyway.

Think of a cylinder of medium radius of curvature, which is normal to a flat plate.

The incoming flow is fully turbulent with a Re number of 12.e6. Boundary layers are building up on both solid surfaces and separation occurs in the corner region farther downmstream of the l.e region. I am using a 3d solver for compressible flow with the Wilcox k-omega turbulence model.

My question is : how sensitive is the separation region to the grid refinement ?( On a single surface, the grid should be refined in the direction normal to the surface; there is no such normal direction in the case of a corner flow). Is it sufficient that the grid is such that my first y+ is below one on both orthogonal surfaces ? Is that so critical? A H-mesh type of grid around a blade is very expensive in terms of nodes; Furthermore, my code being explicit, the cell size in the corner is very small and therefore slows down the convergence of my computation.

Did anyone run into that problem and made an investigation of grid dependency in the separated region ?

Stephane.