[wolverine]

i have been trying to create a mesh for dynamic boundary . like an oscillating wall . i always encounter negative volume error .

[al_th]

Hi wolverine,

I guess the final solution will be dependant of what are the tools that you use, but I have worked on a similar problem (Oscillating wall).

I am using Salome to mesh my geometry
I am using Openfoam to solve both mesh motion and flow equations
Within Openfoam, I am using pimpleDyMFoam application with dynamicMotionSolverFVMesh

The problem I encountered that when the motion of the wall was too big, some of the cells of the mesh collapsed.

I found that there is some motion solver that are able to resolve topological changes (typically when a cell collapses, you have a change in the topology of your mesh), but in my case I had a lot of errors.

The solution I have found is the following :

- Define a python script to do the geometry and the meshing (Salome accepts python scripts)
- Initialise position of the wall
- Start the simulation until it crashes (the only reason my simulations crashes are because of cells that are either collapsing or extending too much).
- Look at the last position of the wall
- Remesh with the current wall position
- Map the result of your previous mesh to your new mesh.
- Restart simulation at the last timestep with the new mesh.

Everything is scripted in bash, and this is a little bit tiresome, but it works quite well at the end, and it is doing what was expected !