On 10/16/2017 08:55 AM, Mark Ma wrote:
> So when you visualize the solution, the error is at the boundary
but it looks
> correct in the interior?
>
> Yes, it is. Thereafter, the error at boundaries does propagate and then
> interfere with the interior.
From the pictures you posted in a follow-up, it looks like the boundary
values are actually correct, but that the problem starts one layer of cells
into the domain. Do I see this correctly?
Yes, exactly. And if I use the BC values as 0, then it seems OK now (see figs
below). What if I want to apply some value other than 0, this problem seems
annoying.
Yes, bugs are highly annoying indeed :-)
It almost looks to me like you're applying both Dirichlet values (via the
ConstraintMatrix) and Neumann boundary values (via a boundary integral). But
then I haven't taken a look at the code, so I can't really say for sure.
Best
W.
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Wolfgang Bangerth email: bange...@colostate.edu
www: http://www.math.colostate.edu/~bangerth/
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