Regularization of eddy-current formulations using discrete grad-div operators

Discrete formulations based on the consistent finite integration technique for magneto-quasi-static problems involve the solution of either singular or very ill-conditioned algebraic systems of equations. For these formulations a regularization based on an augmentation with discrete grad-div-operators is proposed, extending the ideas in Hahne and Weiland (1992) and Bossavit (2000). Possible effects on the spectra of the algebraic systems are discussed and confirmed in numerical experiments.