Comparison of analytical and numerical integration techniques for the boundary integrals in the BEM-FEM coupling considering TEAM workshop problem no 13

When the BEM-FEM coupling is used for the solution of a boundary value problem the domain is decomposed into a multiply connected BEM subdomain and generally several FEM subdomains. Magnetic materials are treated in FEM subdomains only. To keep the discretisation process simple, the parts containing magnetic materials coincide with the FEM subdomains. The surrounding air space is described with the help of boundary elements. The coupling of both methods is carried out on the surface of the magnetic materials. The solution of problems discretized this way shows that the accuracy of the results strongly depends on the accuracy of the boundary element integral calculation. Therefore either a big number of Gauss points or an analytical integration scheme has to be used for the calculation of the BEM integrals.