Dear all --
I would like to withdraw my question. My blithe assertion that there
had to be a solution was naive. It turns out in going from a stream
function to a pressure formulation, my boundary conditions had become
non-local.
Thus fipy was not giving me a solution because there was no solution --
which tends to give any solver fits. My apologies for wasted time.
Jamie
On Thu, Apr 13, 2017 at 3:10 PM, Pringle, James <james.prin...@unh.edu>
wrote:
> Dear all --
>
> I need to solve a second order PDE in 2D of the form
>
> A(x,y)*(eta_xx+eta_yy)+B(x,y)*eta_x+C(x,y)*eta_y = 0
>
> on a rectangular domain. On three sides there is a BC of no normal
> gradient. On the fourth side their is a Cauchy boundary condition:
>
> @x=0, eta_x=D(y) *AND* eta=0 @x=0
>
> Lets assume that there is a solution that meets these boundary conditions
> (i.e. I have not screwed up). Should fipy be able to solve this by
> specifying (*both at the same place, *x0side)
>
> var.constrain(0., where=x0side)
> var.faceGrad.constrain(D_rank2, where=x0side)
>
> Or will this break the numerics? My actual problem is considerably more
> complex, and I want to check that this is even plausible before starting
> down this path. I can make this boundary simpler, but at the cost of
> considerable complexity elsewhere.
>
> Thanks,
> Jamie Pringle
>
> Director Ocean Process Analysis Laboratory in the Insitute for Earth,
> Ocean and Space
>
> Associate Professor of Earth Sciences
>
> University of New Hampshire
>
> http://oxbow.sr.unh.edu
>
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