I am using a mesh made in Ansys with minimum mesh element size of the order of ten microns. After solving it in CFX for laminar flow model I am not getting proper results and this happens even for some analytical test cases of say combined couette and poiselle flow. Can someone tell me if there is any problem with this mesh size?

thanks.

It's hard to tell with such little information provided.

Do a mesh dependency test and see how sensitive your solution is with various mesh densities used.