Discussion Forum

Caveat: I'm not up to date on the latest built-in post-processing features of the AC/DC module. BUT... even if you have a very old version of Comsol you can always use stored energy to compute capacitance or inductance! Do you have/know the applied voltage? If so, you can simply set where you compute the total electric energy by integrating the electric-field energy density over the volume. Then just solve for C. Similarly, to compute inductance, you can simply set , where I is the applied (known) current and is the total magnetic energy (which you get from doing a volume integral of the magnetic field energy density), and then solve for L. Frankly, I wouldn't be surprised if these computations are now simply offered/selectable as menu pull-down items in post-processing (and with probably better accuracy than if you plug in the equations yourself), considering all the years that our friends at Comsol have been working on this software. :) I encourage the real AC/DC module experts to chime in...

I couldn't figure out how to find the applied voltage. I tried doing the magnetic and electric fields interface to find this instead of just magnetic fields, but I couldn't figure out how to make it work when I was modelling my coil as a numeric homogenized multiturn.

Will the interface allow you to specify a voltage type of source (rather than a current type of source)? If so, you'll then know the voltage for that, and the computed capacitance should be the same (assuming your problem is linear) as it would be in your original specification. Note: To improve your odds of receiving more or better suggestions, consider posting your .mph model to the forum.