On Wednesday 09 April 2008 14:49:03 Dag Lindbo wrote: > 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.
Yep, I read some of the stuff > 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. Many thanks! I will look into that form file! Johan > 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
