Hi Tri Dat,


I had recently the same problem with parallel computation on a realistic 
reservoir grid where also the horizontal dimensions are much larger than the 
vertical. The error message was the same. Bernd gave me the hint to install 
SuperLU. However, after installing SuperLU the error was only changed to:

“Newton: Caught exception: "NumericalProblem

>>[newtonSolveLinear:…/dumux/dumux/nonlinear/newtoncontroller.hh:380]:

>>Linear solver did not converge"



Maybe installing SuperLU will solve your problem. My problem is also still 
unsolved, thus, any hints are welcome. I am also using a fully implicit 
cell-centered model. The same simulation is working when started on only one 
processor and the same model is working in parallel on more simple grids.



Kind regards

Birger





Von: Dumux [mailto:[email protected]] Im Auftrag von Tri 
Dat NGO
Gesendet: Dienstag, 24. November 2015 20:07
An: DuMuX User Forum
Betreff: Re: [DuMuX] Convergence problem for 3D simulations (2p cell-centered 
model, ALUGrid)



Sorry, I forgot to add my files.

Kind regards,
Tri Dat



2015-11-24 20:03 GMT+01:00 Tri Dat NGO <[email protected]>:

Hi Dumuxers,

I would like to run parallel simulations of CO2 injection into a 3D reservoir 
of which the horizontal extents are much higher than the vertical one: Lx/Lz = 
Ly/Lz >> 1 (e.g. a reservoir of 1000m x 1000m x 50 m). A 2p cell-centered model 
is used.

The domain is described on a cartesian grid of 100x100x100 (1E+6) cells. The 
CO2 is injected into the domain at X=500m  and Y = 500m by using the Peaceman's 
well model (bhp). The pressure at the boundaries perpendicular to the Y-axis is 
set to the initial hydrostatic pressure. All others boundaries are no-flux 
Neumann boundaries. At the first step, we consider, for simplicity, an 
homogeneous reservoir. You can find in attachment the *.hh files of my test.

The simulation converges only if the reservoir is anisotropic (Kxx/Kzz = 
Kyy/Kzz >>1), meaning that the medium is lowly permeable in Z-direction. 
Nevertheless, when the domain is isotropic (Kxx = Kzz), a problem occurs: 
Newton solver did not converge. The error message is "MathError 
[mgc:/home/share/soft/dumux-2.6/include/dune/istl/paamg/amg.hh:825]: Coarse 
solver did not converge".


Moreover, the same test works correctly on isotropic but thicker domains (e.g. 
1000m x 1000m x 250 m, the grid is always of 100x100x100).

I don't understand why a same test works on a grid but not on another grid. Is 
this related to the numerical scheme (fully-implicit, cell-centered)?


Any help will be greatly appreciated!



Kind regards,

Tri Dat





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