Approximate boundary-flux calculations (Q798066)

A technique for determining derivatives (fluxes or stresses) from finite element solutions is developed. The approach is a generalization to higher dimensions of a procedure known to give highly accurate results in one dimension. Numerical experiments demonstrate that certain difficulties are associated with corners in the higher-dimensional extensions and two variants of the method are examined. We consider both triangular and quadrilateral elements and observe some interesting differences in the numerical rates of convergence. Finally, this post- processing scheme is tested for nonlinear problems.