Build the Scharfetter-Gummel stabilized stiffness matrix for a diffusion-advection problem.
The equation taken into account is:
- div (alpha * gamma (eta grad (u) - beta u)) = f
where alpha is an element-wise constant scalar function, eta and gamma are piecewise linear conforming scalar functions, beta is an element-wise constant vector function.
Instead of passing the vector field beta directly one can pass a piecewise linear conforming scalar function phi as the last input. In such case beta = grad phi is assumed.
If phi is a single scalar value beta is assumed to be 0 in the whole domain.
See also: bim1a_rhs, bim1a_reaction, bim1a_laplacian, bim2a_advection_diffusion.
Package: bim