> I would like to set boundary values for the normal derivative. In the
> element I use this is a degree of freedom. So when I solve problems with
> homogeneous conditions there is no problem, but when solving with
> inhomogeneous conditions I get terrible results. I use the
> MatrixTools::apply_boundary_values function. Can someone explain what I
> am doing wrong?
Is the degree of freedom the normal derivative at a point, or is it the
mean value of the normal derivative along the edge, or anything like this?
If this was the case, then you would have assigned a multiple of the
correct value as boundary values.
In general, what happens if you have a problem with zero right hand side
and nonzero boundary values on a mesh with uniform mesh size? Do you get a
solution that is correct up to a multiplicative constant?
Best
W.
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Wolfgang Bangerth email: [EMAIL PROTECTED]
www: http://www.math.tamu.edu/~bangerth/
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