[lr103476]

Dear all,

Besides the 3D flapping wing stuff I am also working on some fluid structure interaction problems.

In order to test the icoFsiFoam solver which came with the latest development sources (from prof. Jasak, 28 March 2007), I created a test case of a flexible plate attached to a rigid cylinder. At low Reynolds numbers the plate will start oscillating according to the von karman vortex street. This is particular interesting when the density of the structure approaches the density value of the fluid and when the structure equals very low stiffness. Only then significant deformation can be observed, which is what we want.

Unfortunately, at similar densities (structure / fluid) and low structural stiffness this problem is very strongly coupled. Together with the partitioned approach which is used by icoFsiFoam, this lead to serious divergence problems when:

1) The density ratio is of the order O(1),
2) The structural stiffness is low,
3) movingWallVelocity BC is chosen on the flexible plate. The divergence of the solution due to this BC is thought to be the result of the alternating correction of the ALE flux which is accounted for in movingWallVelocity BC.

Detailed info on this problem can be found on my website:
http://www.aero.lr.tudelft.nl/~frank...d/problems/fsi

I really hope that someone may provide some usefull hints and / or solutions. Eventually, when anyone would like to try this testcase I could post it here or on my site.

Thanks and regards,

Frank