I want to solve an extra field along with the structural mechanics module in COMSOL. Basically, I want to use the stress which you obtain by solving a linear elastic problem, calculate the pressure (hydrostatic part) and solve another equation where the dependent variable is a function of gradient of this pressure.

I am very much new to COMSOL, and would appreciate any help.

My equation would be something like:

dot{u} + div. grad{pressure} = 0, where u is the dependent variable and pressure I get after solving the structural problem.

Thanks in advance.