On mixed boundary element solutions of convection-diffusion problems in three dimensions

Abstract Three-dimensional boundary element solutions of steady convection-diffusion problems are presented. Numerical properties such as stability and accuracy on boundary element solutions based on a discretization using mixed boundary elements are compared with those of constant elements. It is found that boundary element solutions are unconditionally stable in space, nd that their relative errors to exact solutions hardly depend on the Pecler number. These results prove that the boundary element method is superior to domain-type numerical techniques which have a criterion of numerical stability and whose approximate solutions depend to some extent on the Pecelet number. The advantage of BEM using mixed elements, as compared with constant element solutions is also shown.