time step from the Courant number
 

I am doing very high speed calculations and the Courant number seems to be controlling the time step in some cells (the calculation diverges for Co>1.5, implicit, density solver). Does the time step differ in different cells due to the Courant number limit? Is the actual time step = min(specified time step, time step from the Courant number)? Is there any way to know the time step in each cell (in a UDF perhaps)?