Dynamic Mesh (DEFINE_GRID_MOTION)
 

I would like to transform/change a boundary condition in the middle of a simulation.

I have had success using a UDF and the DEFINE_GRID_MOTION routine to prescribe a desired wall movement in previous models. The next step is to use the UDF in a more complex model.

The problem with the new model is that as the walls move, they come into contact with one another which soon after causes an error. I would like to keep a wall boundary between the mesh when the walls come in contact (not allow flow to exchange in between the two walls).

So, as the moving mesh walls come in contact we would like the boundary condition to be switched from a moving wall to a stationary wall. This will allow the rest of the model to continue to move without error.