According to your picture, the cylinders never touch each other, is that right? nAs Rob said, both overset mesh and dynamic mesh with remeshing are possible. For your case, I believe that overset mesh is good choice and I expect it to be computationally cheaper. With overset, your meshing will be simpler and nicer because each cylinder has its own mesh sorted around the circle. Also, you can easily introduce both rotational and translational motions. nJust make sure that around solid objects meshes are fine enough so that there are ideally at least 4 elements between the walls at each moment. That avoids formation of orphan cells.