Calculation of transient 3D eddy current using edge-elements

The calculation of transient 3-D eddy current using edge elements in the modified A-method is presented. Quadratic 36-edge elements on the 20-node isoparametric elements are proposed. Specifically, the test problems of a square plate and a hollow sphere are solved with linear 12-edge and quadratic 36-edge elements, and the results are compared with the analytical solutions. The results using the two types of elements agree well with each other and with the analytical solution, demonstrating the applicability of these elements for eddy-current calculation. The spatial distributions of the current and magnetic field in elements interpolated by shape functions are approximated better by quadratic elements with fewer degrees of freedom than the linear elements. The accuracy of both types of elements is nearly the same in the test problem of a hollow sphere if the size of the quadratic elements is double that of the linear elements