Discussion Forum

I am trying to model the diffusion of current from an axisymmetric conductor into a surrounding antisymmetric conductor of differing conductivity. I would like to observe the diffusion of both axial currents and in-plane currents.

I model the diffusion of the azimuthal currents using the "Azimuthal Induction Currents, Vector Potential" application mode from the AC/DC module. The in-plane current diffusion is modeled using the "Meriodonal Electric and Induction Currents, Potential" application mode. Everything is 2-D axisymmetric. Run individually, both of these modes diffuse the current as expected.

My problem is that I need to couple the two modes by enforcing the force free constraint:
B = C*J
where B is the magnetic field, C is s constant, and J is the current density. This says that the current flows along the magnetic field lines, so there is no Lorentz force.

I have no idea how to enforce this constraint to couple the two application modes (I am fairly new to Comsol for anything beyond simple electrostatics problems). If anyone can offer advice, it is greatly appreciated.

Thanks,
Nick