Evaluation of two commercial finite element packages for calculating AC losses in 2-D high temperature superconducting strips

This paper compares the speed and accuracy of two commercial packages based on the finite element method (FEM) for calculating the AC losses in high temperature superconductors (HTS). The softwares investigated in this paper were COMSOL Multiphysics and FLUX 3D (2D module). This choice was motivated by 1) the ability of the packages to model the nonlinear resistivity of HTS (mandatory condition), 2) the possibility to extend the analysis to 3-D in the future, and 3) the possibility to solve the associate thermal problem (with additional modules). Nevertheless, in this paper, the analysis was restricted to 2-D and no thermal coupling. To generate objective comparisons, the base case of a 2-D rectangular strip was considered under three important regimes, i.e. 1) transport current, 2) perpendicular applied field, and 3) both excitations simultaneously. In all cases, the superconductor was modelled with a classical E-J power-law characteristic. The results are summarized in a number of graphics showing the sensitivity of each package to 1) the number of elements in the mesh, 2) the n-value in the power-law characteristic, and 3) the aspect ratio of the strip.