dynamic mesh in openfoam
 

Hi:
I am wondering if any one know the mechanism of dynamic mesh handling in openfoam. I have the following questions:
1. after moved the position of grid nodes, do I have to interpolate the physical properties from the old one the the new one. I have read a few papers about this, they all did not mention such operations, I don't know why.
2. the motion of the internal nodes in openfoam is controled by solving a Lapalacian equation, I am wondering why to do so, just to keep the mesh in a good quality or it have physical meanings. Can I move the points arbitrarily with my own rules?
Thank you in advance.