Learning Forum

[shahim.ha]

what settings of smoothing and remeshing we should take for turek hron case , so that we can avoid negative volume error.

[Federico]

Hello, 

What types of cells are you using in your mesh? Can you show a screenshot of your setup?

The default remeshing/smoothing methods should work fine for this case: unified remeshing with spring smoothing. Negative volume error can also occur if your time step is too large for the resulting displacement.

[shahim.ha]

tetra elements only, with smoothing and remeshing with time step .005 seconds

[Federico]

How does this time step compare with the size of your elements near the moving boundary? Remember time step delta t <= mesh size/boundary velocity.

[shahim.ha]

yes element size is .005 and velocity is 1.5m/s. time step is .001

[Federico]

Time step of 0.001s should be fine then, but 0.005s which you mentioned earlier would be too large. If the problem persists, please provide more details:

What are your remeshing settings?

How are your Dynamic Mesh zones set?

[shahim.ha]

even with that also, I am not getting.

Remeshing- local cell , size interval 1, 0.7.

In dynamic zone interface , i had taken as system coupling and symmetry as deforming

[Federico]

Hello, 

It is really difficult for me to provide specific recommendations if I don't have any visuals of your model or any reference to the zones that you mention.

You can read on the various Dynamic Mesh settings in the Fluent User Guide: 12.6. Using Dynamic Meshes (ansys.com)