The low-frequency performance of H-φ and T-Ω methods using edge elements for 3D eddy current problems

Using edge elements, it is possible to solve directly for the vector magnetic field in the conducting material of a time-harmonic eddy-current problem, and for a magnetic scalar potential in the nonconducting regions. This is the H-φ method. Edge elements also allow the magnetic field, H, to be split into the gradient of a scalar potential, and another, rotational part. This is the T-Ω method. The H-φ and T-Ω methods provide the same answers. However, the matrix equation obtained from T-Ω is better conditioned at low frequencies, and can be solved more efficiently