On Feb 14, 2011, at 8:32 AM, Julien Derr wrote:
> I don't really understand, the gradient of the concentration field is not
> necessarly normal to the side ? or is it ?
> a priori the direction of grad(c) can be different than the normal, no ?
In the FixedFlux case, the boundary condition is definitely n\dot\vec{J}, but
for phi.faceGrad.constrain(), I'm not sure that's true. Wheeler would know for
sure; I think he'll be back tomorrow.
My guess is that phi.faceGrad.constrain(value=mesh._getFaceNormals() *
phi_grad_mag, where=...) would do the trick, but Wheeler may know some
finite-volumy reason for why that's not necessary.
It looks to me like phi.faceGrad.constrain() has only been tested in 1D cases,
where this doesn't matter. Again, Wheeler will be happy to look into this when
he gets back... won't you Wheeler?
