ffc team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

I'm implementing a Stokes solver in DOLFIN (which is just assemble +
solve). Andy will help and we will add all the functionality we need
for mixed systems as we go along, including boundary conditions,
extracting the pressure and velocity for postprocessing etc.

When this is done, it should be really easy to just write down any
mixed system and just have it work.

/Anders

On Tue, Sep 20, 2005 at 10:52:51AM -0500, Robert C. Kirby wrote:
> Good news here...
> Have you considered how to (elegantly) do boundary conditions on  
> mixed elements?  You apply conditions to the velocity but not the  
> pressure.
> 
> 
> Rob
> 
> 
> On Sep 20, 2005, at 10:15 AM, ffc@xxxxxxxxxx wrote:
> 
> >Commit from logg (2005-09-20 17:15 CEST)
> >----------------
> >
> >Add mixed formulation of Stokes to the set of demo forms:
> >
> >P1 = FiniteElement("Lagrange", "triangle", 1)
> >P2 = FiniteElement("Vector Lagrange", "triangle", 2)
> >TH = P2 + P1
> >
> >(v, q) = BasisFunctions(TH)
> >(u, p) = BasisFunctions(TH)
> >
> >f = Function(P2)
> >
> >a = (dot(grad(u), grad(v)) - p*div(v) + div(u)*q)*dx
> >L = dot(f, v)*dx
> >
> >  ffc  src/demo/Poisson.form        1.20
> >  ffc  src/demo/PoissonSystem.form  1.6
> >+ ffc  src/demo/Stokes.form         1.1
> >
> >_______________________________________________
> >FFC-dev mailing list
> >FFC-dev@xxxxxxxxxx
> >http://www.fenics.org/cgi-bin/mailman/listinfo/ffc-dev
> >
> 
> 

-- 
Anders Logg
Research Assistant Professor
Toyota Technological Institute at Chicago
http://www.tti-c.org/logg/