Time and Space Derivatives.
 

Hi All
I am a Masters student. It may be a simple one for most of u. Since I am a beginner, so its kind of new for me. I have a 2-D periodic domain. I am trying to make a simulation of two phase flow in this domain using two fluid model. Now I wish FLUENT to calculate the velocity gradients w.r.t. time and space in this periodic domain for all the phases and write it to a file, say, grad.dat alongwith flow time. How can I define the time and space velocity gradients in a UDF?
Thanks.
Raza.