dolfin team mailing list archive

["Johan Hoffman" <jhoffman@xxxxxxxxxx>]

Is there a demo-form file available for using these operators? Can one
take the avg and jump of an arbitrary function?

/Johan



> What we have implemented for DG is the ability to define integrals
> over interior facets that have contributions from both sides of the
> facet, so you can write
>
>     v('+')*v('-')*avg(v)*jump(u, n)...
>
> It's a little different from what you have in that the integral is
> over all interior facets in the mesh, not just along some given
> surface.
>
> Perhaps you could extract all the cells in the mesh that border to the
> common surface, so instead of having some interior surface, you have
> an interior mesh that contains the surface and each interior facet in
> that mesh connects to exactly two cells, one on each side.
>
> /Anders
>
>
> On Thu, Jan 18, 2007 at 09:24:01AM +0100, Johan Hoffman wrote:
>> Garth and Anders,
>>
>> I am interested in solving a problem where I a priori specifies an inner
>> surface (aligned with cell faces) where the solution is discontinuous.
>> The
>> coupling of the solution over the discontinuity is taken cared of by a
>> surface integral over that inner surface (like a penalty term).
>>
>> For this I expect to need:
>>
>> (1) a data structure with "double nodes" at a predefined surface (=
>> collection of nodes/faces).
>>
>> (2) for the nodes on the surface; the ability to assemble only
>> contribution from either side of the surface for the "double nodes"
>> respectively (where the two sides of the surface may be represented by a
>> MeshFunction for example).
>>
>> (3) a surface integral defined over an inner surface.
>>
>> I suspect that some parts of (1)-(3) is already in place, as part of the
>> DG work? What remains to be done to handle this problem?
>>
>> /Johan
>>
>>
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