Roughly described, a method for determining characteristics of a body by simulation, useful in analyzing semiconductor devices, includes imposing a Delaunay mesh on a simulated body to be modeled, determining a system of node equations describing generation and flux of a set of at least a first physical quantity at each node in the mesh, and numerically solving the system of node equations to identify the physical quantities in the set at each node in the mesh, where the flux of the first physical quantity in the body, as represented in the node equations, is anisotropic. The method does not impose any limitation on the geometry of the device, on mesh elements, or on the orientation of the anisotropy.