An evaluation of the computational error near the boundary with magnetostatic field calculation by BEM

A 3-D magnetostatic field is calculated using the reduced scalar potential method for a two-region model: a current-free iron region with linear and isotropic property, and an air region including the source domain. An unstable computational error near the boundary is investigated from the viewpoints of numerical integration and discretization. Specifically it is shown that near the boundary elements, the calculated results of the magnetic flux density often contain an unstable error. The error is affected by the fineness of the discretization, the point number for Gaussian quadrature, and the distance from the boundary elements. It is found that close integration of the internal field calculation effectively removes the unstable computational error