Eddy-current computations using adaptive grids and edge elements

Results are presented from eddy-current computations using adaptive techniques, based on rigorous a posteriori error estimates. The adaptivity restores the quadratic convergence with grid size of the magnetic energy, despite singularities occurring at corners. A new procedure is introduced to satisfy the solvability condition for the curl-curl equation. The methods are applied to a model of a hydrogenerator, with anisotropic conductivity and permeability. The ungauged formulation with both vector and scalar potentials gives very significant improvements in rate of convergence for this problem. Reasons for the improved convergence are discussed.