Eddy Current Analysis — Losses, Skin Effect & Induction Heating

What is the skin effect and how does it affect eddy current loss calculation?

At high frequency, eddy currents push current toward the conductor surface. Skin depth delta = sqrt(2*rho/(omega*mu)) defines where current density falls to 1/e of surface value. At 50 Hz in copper, delta ~ 9 mm; at 10 kHz, delta ~ 0.66 mm. If conductor thickness exceeds a few skin depths, the effective resistance increases significantly with frequency.

How do you compute induction heating power density distribution in FEM?

Solve the time-harmonic eddy current problem to get induced current density J. Power density is q = |J|^2/sigma (W/m^3). This becomes the heat source in a thermal analysis — a one-way electromagnetic-thermal coupling. You need at least 2-3 mesh layers within the skin depth for accurate results.