Discussion Forum

Hi

I'm trying to model the fluid structure interaction of a flexible raft being towed through water. I've tried to use the build in FSI module. I have modelled the raft as a linear elastic model and the water as the fluid domain and using a stationary solver. The problem is that COMSOL has a fixed fluid/solid interface throughout the whole simulation so if the raft deforms it practically drags down the water surface. Another problem is that the solid domain must be fixed somewhere to avoid infinite solution, so I can't simulate rigid-body motion.

I have an idea of using a Matlab loop to:
1. Calculate the flow around the undeformed geometry
2. Calculate the deformation of the solid
3. Export the deformed geometry using "Deformed Geometry" feature
Restart the loop with the deformed geometry
The loop ends when the deformation does not change anymore

The new problem is that stresses and strains of the deformed solid geometry are not preserved from loop to loop.

Does someone have an idea or hints to the following:
Is it possible to simulate an elastic deformation and rigid body motion of a solid?
Any idea of how to simulate fluid structure interaction, where the fluid/solid interface change?
Any idea of how to preserve the stresses and strains of a deformed geometry?
Alternatively project the Total stress from the fluid on a deformed geometry to an undeformed geometry?

Any help will be greatly appreciated.

Thanks

Best regards
Kennet