Dear Dmitry,

this is a known current bug 
(https://git.iws.uni-stuttgart.de/dumux-repositories/dumux/-/issues/864 
<https://git.iws.uni-stuttgart.de/dumux-repositories/dumux/-/issues/864>)
There are some ideas for a fix but due to limited developer resources we are 
currently focussing on a better linear solver interface that includes a fix for 
this, instead of a temporary fix.
A draft is here: 
https://git.iws.uni-stuttgart.de/dumux-repositories/dumux/-/merge_requests/2113 
<https://git.iws.uni-stuttgart.de/dumux-repositories/dumux/-/merge_requests/2113>

What helps:
* You can either use a criterion that does not use the residual (relative shift 
criterion) in the Newton.
* Or you have to compute the residual norm by using the correct consistent 
parallel ScalarProduct.
For how to set up the ScalarProduct have a look at MR2113 
(https://git.iws.uni-stuttgart.de/dumux-repositories/dumux/-/merge_requests/2113
 
<https://git.iws.uni-stuttgart.de/dumux-repositories/dumux/-/merge_requests/2113>)
 and/or the parallel solvers (e.g. 
https://git.iws.uni-stuttgart.de/dumux-repositories/dumux/-/blob/master/dumux/linear/istlsolverfactorybackend.hh
 
<https://git.iws.uni-stuttgart.de/dumux-repositories/dumux/-/blob/master/dumux/linear/istlsolverfactorybackend.hh>)

Best regards,
Timo



> On 29 Jun 2022, at 15:57, Dmitry Pavlov <[email protected]> wrote:
> 
> Hello,
> 
> I have a 1D radial mode porous flow simulation implemented via
> 
> Dune::YaspGrid<1, Dune::EquidistantOffsetCoordinates<double, 1> >
> 
> and
> 
>             struct GGTraits : public BoxDefaultGridGeometryTraits<GridView>
>             { using Extrusion = RotationalExtrusion<0>; };
> 
> I am using the Box method. My program works well when ran as single. With 
> MPI, however, I get the following message from fvassembler.hh:
> 
> Warning: norm calculation adds entries corresponding to
> overlapping entities multiple times. Please use the norm
> function provided by a linear solver instead.
> 
> and the solver does not converge because the residual does not change.
> 
> I am seeking advice.
> 
> 
> Best regards,
> 
> Dmitry
> 
> 
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