----source term help--please help
 

Hi I want to add (d/dx)((du/dx)+(dv/dy))as x-momentum source term. Here I can write source=C_DUDX(c,t)+C_DVDY(c,t). But how to write dS[eqn] I do not know. Here dS[eqn]=second derivative of source with respect to x.

Also to add ((du/dx)+(dv/dy))**2 as energy source term. Here what will be the source and dS[eqn].

Here all are partial derivatives. If anybody help me I will be grateful to him. Thanks a lot. Mech.