Mesh Deformation / High Pressure

Simon

Hi everybody!

I am having problems when using the mesh deformation functionality of cfx5. I have a 2D circular geometry with a thin membrane inside.

This membrane is displaced (mesh displacement) according to the pressure difference of both sides of the membrane using CEL (using integrated values force() and area()). The shape of the membrane is a nearly quadratic function (which drops to zero where it is connected to the wall. I am also using a step function to guarantee that the displacement at the wall is exactly 0).

See picture of geometry (size approx 3mm x 3mm): http://www.tyberis.com/geometry.png

The fluid comes into motion due to small momentum sources.

If I leave the mesh displacement exactly zero (no mesh displacement) then the pressures value in the domain look okay (within [-0.1, 0.1] Pa). But as soon as there is a small displacement of the membrane (even not noticable to the eye), the pressure gets very high in the whole domain (range [-1000, +1000] Pa)

Does anybody have an idea why the pressure explodes in this case? Does anybody have an idea what I could try? I have tried a lof of different parameters but without success.

Thanks for any help!