I'm interested in two ways FSI (fluid structure interaction) in CFX and workbench. I've modeled a floating cylinder in wave (multiphase flow, air and water). Cylinder is moored and it can move only in 1 direction (rise and sinkage in water). My question has 3 parts.

1) Solve converges in fluid and structure fields. But there is a trouble. Suddenly negative volume mesh occurs and run is terminated. The rigid body motion is not very big. Motion of cylinder is about 10% of fluid domain length (CFX domain). I extended dimensions of domain and I increase number of mesh but these are useless. I've used tetrahedral mesh which is fine near the cylinder (fluid solid interface). What can I do?

2) I want to calculate rigid body motion. I don't need that software calculate structural effects and induced stresses. It wastes time. In Workbench, rigid dynamic motion analysis hasn't got FSI boundary condition. What do you offer me?

3) can FLUENT calculate rigid body motion for a rigid structure which moves due to flow forces? For example a floating cylinder in wave?

I would be very grateful for any advice

Hi, You can try sesam.... it has Patran/CFX5.6 based GUI and easier to mesh. It gives detailed analysis for seakeeping.

Regards,

Sal.