[aspect-devel] Weird pressure with periodic BC's + direct solver?

[Wolfgang Bangerth]

On 09/06/2017 11:38 PM, Jonathan Perry-Houts wrote:
> Thanks for the suggestion Wolfgang! It does indeed only show up at 
> hanging nodes (figure attached). And it apparently only happens with 
> both the direct solver, and 'remove null space' enabled at the same time 
> (also attached).
> 
> When those two options are both enabled the pressure solution is zero 
> everywhere, but gets these little (~ 1e-6) jitters at hanging nodes. 
> Definitely sounds like a ConstraintsMatrix problem.

Can you compare the direct solver/iterative solver code paths in 
solver.cc to see whether we may accidentally forget to call something 
like constraints.distribute(...) on the solution vector if we use the 
direct solver?

Best
  W.

-- 
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Wolfgang Bangerth          email:                 bangerth at colostate.edu
                            www: http://www.math.colostate.edu/~bangerth/