On Sun, Oct 9, 2011 at 5:19 PM, mor yaakobi <moryaak...@gmail.com> wrote:
> Hello,
>
> I'm new to both FiPy and Gmsh.
> after days of struggling with solving Laplace eq. for a 3D space and a
> sphere,
> with robin boundary condition on the sphere's surface, and fixed value b.c.
> near "infinity",
> I think it is time I'd ask for advice:
>
> given a sphere with radius r=R,
> and the B.Cs:
> 1. -\alpha c + \frac{\partial c}{\partial r}= 0 , where r=R
> 2. c=0 , where r>>R
This appears to be a 1D problem. What introduces the higher dimensions?
> I want to solve Laplace equation: {\nabla^2 c = 0}
> outside the sphere.
>
> now, what would be the better approach? and how can I overcome the following
> problems?
>
> 1.generate a sphere using gmsh.
> define the robin BC using getExteriorFaces() on the sphere's surface.
> the problem: how can I define BC near infinity? (r>>R), e.g. for R=1,
> r=100 is infinite enough.
It's no different from any other boundary condition.
> 2. generate a sphere with spherical hole in the middle.
> define the BC in the "infinity" using getExteriorFaces()
> the problem: how can i define the robin BC on the inner hole-sphere
> surface?
Identify the interior faces using (exteriorFaces & r < R) and make a
boundary condition.
> or is there a better way?
You could mask the inner region with source terms if you're having
issues with generating a shell in gmsh.
--
Daniel Wheeler
--
Daniel Wheeler
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