symmetryPlane vs slip and zeroGradient (possible bug)
 

Hi,

I'm currently running a LES simulation of a cylinder, with a prescribed sinusoidal movement, in a steady stream. The mesh boundary has the shape of a cuboid. I have employed the following boundary conditions in the pointDisplacement file, top/bottom [fixedValue (0,0,0)], left-side/right-side [symmetryPlane], Inlet/Outlet [fixedValue (0,0,0)] and for the cylinder [oscillatingDisplacement, amplitude(0.02435 0 0),omega 1.759].

The problem arises when I increase the grid resolution. I then get a perturbation in the pointDisplacement field (in the y and z-direction! according to the boundary conditions the analytical solution should be zero everywhere!). It starts on the symmetryPlane boundary and spreads and in the end makes the simulation crash. Changing the BC to be slip (vectors) and zeroGradient (scalars) works!

Should there really be a difference?

Best regards,
Andreas FEYMARK

Could you send your case or better still a small case which reproduces the problem?

H