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[Johan Hake <hake@xxxxxxxxx>]

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 :).

Do you think this method could be usefull to try out? If so, how should this 
be formulated in FFC.

Many thanks in advance!


Johan