Discussion Forum

Hi,
I just started working with Comsol, because I want to solve the following problem:
I am compressing a polymer, which results in a compression heating. The adiabatic case can be calculated with the Joule-Thomson-equation: (alpha*T*delta p)/(rho*cp)
I solved this iterative in Matlab for fast compression (adiabatic) and the results are in good agreement with my measurements.
Now I want to combine the compression heating with heat transfer using Comsol. That occurs when the pressure is applied slower. For example, a pressure of 10 bar could be applied in 0.1 or 1 s. The slower the compression, the more time is for heat conduction.
After some tutorials, the heat transfer itself isn't problem. I tried adding a heat source, but even if I would calculate Q in Matlab, I couldn't implement it time-dependent. As the heating itself depends on the temperature (T) and the density (rho) depends on the increase in pressure (delta p), I couldn't find a way to define it as a variable in the global definitions either.
But I am looking for a way to couple it with a time-dependent heat source.

Any suggestions, what I could try to couple my heat transfer with a time-dependent heat source ?

Thanks a lot,
Natalie