[nguyenhoa]

Hi everybody
I am facing to a dynamic meshing problem that has not yet found a solution. Hope someone can help me find a solution!
Geometric model of the problem as figure attached below.
The content mainly focuses on the red border, which is moving in each calculation time step.
At time "t0", this boundary is in position 0-0. After each time step "t", this boundary moves a length "s = u * t" with u being a given displacement velocity. thus, at the time "t1 = t0 + t" it will move to position 1-1, "t2 = t0 + 2t" will reach position 2-2, ... similarly until "t13", it will reach position 13-13 and stop moving.
The law of moving is similar to using offset tools in other CAD software, so this boundary in the moving process will be shortened over time.
I have read and know the function udf DEFINE_GIRD_FUNCTION can describe this moving but I could not find the rule to write how to move. Can someone help me find a solution, thank you very much