Discussion Forum

Dear Daniel,

Yes there is. If you click on the physics type, for instance "Fluid Flow", and then scroll down a little bit, you will see a header "Dependent variables". If you click on this, you will see the names of pressure, velocity, etc. You can rename them there as well.

If you're looking for variables not explicitly solved for, let's see the electric current, then I would advice to go to a surface plot and look up the name. In this case, ec.Jx for the current in the x-direction. Alternatively, you can look at the Equation View in each branch of the physics interface (for instance, Electric Currents). It will also show you how the quantity is calculated. This requires that you turn on "View more options", which you can find in Options=>Preferences.

Sidenote: for several couplings, there is a pre-defined dropdown menu that does the trick for you. For instance, if you have an Electric Currents physics interface, and add a Heat Transfer interface, then if you add a Heat Source, you will be able to pick the resistive heating effects from a dropdown menu. This is also possible for several different couplings.

Best regards,

Ruud Borger
COMSOL

Thanks a lot!

Hallo!

I am also curious about how coupling of different physics works!

Lets say I have geometry domains d1...dn and I want to compute different influence of electric fields using EC modules ec1...ecn simultaneously (so there should be dependent variables V1....Vn calculated for every domain)

My question is, how can i "adress" the solution of this dependent variable of given module and domain (for example V1(d1)) in an expression, so i can re-use it while solving another module?

When i set probes on every domain, that are "sensing" the electric potential, with expression V1...Vn, COMSOL starts to use an enourmous amount of memory (>13GB) but does not solve anything.

Thank you very much!
Kind regards
Paul

Hi

in which sens are you coupling different physics as you are always in EC ?
are you scanning a dimension, or solving a complex model in several modules/steps, but then how do you check mutual (bidirectional) coupling ?

Sorry but I didn't really catch your issue there ;)

--
Good luck
Ivar

Hi Ivar,

Exactly, I would like to create a dynamic system with n domains, that are sensing and producing electric potential at the same discrete timestep. The amount of outcome voltage is calculated with a nonlinear function at the domain boundary, but the input of this function shouldn't include the voltage excited by the domain itself.

So I thought of computing the influence on each domain (caused by every else, but this domain) in a separate module and couple the outputs into one final module where one can sense the potential for the next step.

I know, it sounds a bit complex, but there should be a way to realize it. I am only missing the way to "address" each domain at V1..Vn

Thanks a lot for your time and attention!
Paul

Hi..... I wanted to couple the Turbulent flow solver to the Porous flow solver by taking the pressure given by the Turbulent flow as the inlet condition for the Porous' flow.......So what do I put as the value of pressure in the Porous flow as ?? If I put 'p'..... How will it differentiate between the pressure given by the turbulent flow and the pressure given by the Porous region flow...???

I have problem coupling CFD with ac/dc module. Is it possible to write user defined equations in comsol that can couple both CFD and ac/dc module?