Towards increased speed computations in 3D moving eddy current finite element modelling

A finite element scheme used to model eddy current problems with motional velocity is described here. The formulation is a variation on the A-ψ method. An additional Minkowski-transformation term is required to take into account the velocity. However, computational instability arises when the velocity increases to the point that the first order velocity terms severely dominate the second order diffusion terms. The method presented here uses upwinding to help regain stability. An additional degree of stability is inserted at higher speeds by using a lower speed result as an initial vector. This leads to a reduced permeability in saturated regions which counterbalances to some extent the increase in velocity. The method is validated by experimental measurement