domain deformation while doing moving mesh

Right now i am solving a moving mesh problem where the particle is moving in the domain. i have used moving wall and prescribed mesh velocity for the problem. It is doing fine for sometimes , however the geometry of the domain is changing with the moving mesh after sometime. I have attached the picture of mesh for two different times.


I need some suggestions so that the domain won't change with the moving mesh deformation. Please respond as soon as possible.