User defined stretching law
 

Hi everyone!
I' m new with cfd, and I'm making a les simulation on a channel flow. My geometry is a parallelepiped and my mesh is uniform (and with a fixed number of divisions) among spanwise and streamwise directions, while it should respect a stretching law among the direction normal to the wall (with a fixed number of divisions, too)
Do you know how can I define this law with ansys meshing or fluent (within workbench 14.0) to put the nodes of the grid exactly where they are supposed to be?
Thank you very much :)