On Fri, Aug 25, 2017 at 10:34 AM, Renato Poli <[email protected]> wrote:

> Hi,
>
> I need some help here ...
>
> I am having trouble to understand what is going on with a boundary
> integral.
> I have solved a Poisson problem for pressure in a 2D mesh, as a model for a
> incompressible water flow in porous media.
> The mesh (Tri6 elements) has a near-circular polygon in the middle
> representing an injection well.
>
> RHS of the equations are zero except in boundaries dofs. Dirichlet boundary
> conditions are imposed using a penalty both on the well and on the external
> boundaries to represent fixed pressure. (the solution looks ok - seems to
> work)
>
> To validate the solution, I am trying to estimate the water flow both in
> the well and in the external boundaries (they must be identical and match
> the analytical solution). I therefore calculate the normal pressure
> gradient and integrate in the whole boundary path.
>
> When I use first order variable, the results are "almost correct". But when
> I use second order , it is absolutely off.
>
> I am using the code below to do the integration. I tried many alternatives,
> no success.
>
> Any idea of what I am doing wrong?
>

The code seems OK to me, although you should not need to call
fe_face->reinit() inside the loop over boundary ids.

What is _sys_solution?

-- 
John
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