I am working on a problem where I need to have an object, which is influenced by the flow using the 6 DOF solver, which will come into contact with another surface. I have been having issues with negative volumes which seem insurmountable using an unstructured grid. Anyone have any experience with this? Is is posible with an unstructured mesh?

Any feedback at all would be greatly appreciated.

-Philip-

In the interim I've tried simulating a block falling onto a surface from a considerable height. I used an unstructured mesh and was able to preview the remeshing up until the block was in very close proximity to the surface. Then, as encountered before, negative volumes were created. It seems as though it might be impossible?

Might anyone have any experience with a similar problem? I've tried reducing the mesh size and time step together and independently but invariably, as the two surfaces come into very close proximity, negative volumes are created by fluent.

Thanks a bunch.

I don't think it's possible to ever get complete contact between the two surfaces using Fluent's dynamic mesh. The best you can hope for is to do what you've been doing and refining the grid and timestep. This will get the objects close but they'll never touch.

That's been my experience, at least. You might want to try using a sliding mesh with layering. Read through the fluent help manual and they might have something on it this problem.