Hello

My problem is a 3D model of two cylinders intersecting at 45 deg. I've constructed a half model and set symmetry as B.C. After calculating and checking the results it seems that Symmetry B.C is not working. The normal velocity to the symmetry B.C which is supposed to be zero has non zero values.

Thanks Miri

The symmetry BC in fluid mechanics is not just geometry but flow field too, I have met a good number of CFD practioners that commit that mistake If your normal velocity is not zero, then using Symmetry BC is not valid, there must be vortices in that region of flow