Discussion Forum

I just started to use COMSOL and I am working on an Electric Currents (ec) model having difficulties transforming the boundary conditions and initial conditions from the old version(3.2 conductive media DC) to the new one.

Here is the situation that I need some advice on:

1. In the 2D-axisymmetric model I need to have a surface with a floating-potential boundary condition and specified with the source current (total current as in v3.2) flowing through the surface, rather than a spatially-constant current density. How do I set the floating-potential boundary condition in v4.2?

2. One of the boundary surface has a capacitive layer, which I plan to set using distributed impedance boundary condition. Is it possible to have the reference potential set as a time-dependent variable that updates with simulation time? In that case, I can set the boundary in 1 as a fixed potential. Also, is it possible to set the electrical conductivity of the impedance as a surface-voltage-dependent variable (simulating chemical reactions)? I might need to the conductivity to change with surface potentials in later simulations.

3. The initial value of the potential at t=0+ in the simulation space has an non-uniform analytical solution, which I would like to calculate outside COMSOL, store and then apply to the model. How do I set a non-uniform initial potential value?

Thanks