Johan Hake wrote: > Hello! > > I am simulating the diffusion of Calcium ions within an electrical field, > i.e., solving the Diffusion Advection (Convection) equation. The field is not > solenoidal. > > This workes fine for fields with small absolute values. When the typical > field > get above a certain value, the solution starts to behave peculiarly. It > converges but I get negative values of concentration and it becomes very > dependent on the mesh size. > > My bilinear Diffusion Advection form with homogenous Neumann boundaries look > like: (skipping konstants) > > ( dot(grad(v),grad(u)) + u*dot(E,grad(v)) )*dx > > where v is the test function, u trial function and E the electrical field. > > Having basic FEM knowledge, I have heard of the stabilizing method of > Petrov-Galerkin, but I have no experience using it. I found some very usefull > explainations in Dag Lindbos Master thesis :).
Wow, you found that! > > Do you think this method could be usefull to try out? If so, how should this > be formulated in FFC. Yes, SU/PG is very solid. I believe I cite the original paper if you need the details. As I recall, Garth has published papers on this topic. In any case, there used to be a convection/diffusion module in DOLFIN. It contains both the forms and routines needed to compute the stabilization. Take a look under src/modules/convdiff/dolfin/ in DOLFIN 0.6.4. It was probably Garth who wrote this module. Cheers! /Dag > > Many thanks in advance! > > > Johan > _______________________________________________ > DOLFIN-dev mailing list > [email protected] > http://www.fenics.org/mailman/listinfo/dolfin-dev _______________________________________________ DOLFIN-dev mailing list [email protected] http://www.fenics.org/mailman/listinfo/dolfin-dev
