Hi Bernd,
Thanks a lot for your quick attention. However, with your input file, and grid
resolution 100x100, I got the same exceptions. I also tried to increase
ResidualReduction parameter even further without any luck.
It puzzles me that the code runs at lower resolution but not at higher...
-Shawn
From: Bernd Flemisch <[email protected]>
To: DuMuX User Forum <[email protected]>
Sent: Saturday, March 24, 2012 6:07 AM
Subject: Re: [DuMuX] Permeability heterogeneity and grid resolution
Hey Shawn,
thank you for reporting this. It helps to relax the threshold for the reduction
of the residual that the linear solver is required to achieve. I attach a
corresponding input file, where the parameter is adjusted in line 31.
To me, the default threshold of 1e-12 seems to be very small. We will discuss
whether the default value should be adjusted.
Kind regards
Bernd
On Fri, 23 Mar 2012 12:36:05 -0700 (PDT)
Shawn Zhang <[email protected]> wrote:
> Dear All,
>
> I ran into an issue of 1p model not converging. After a series of tests, I
> trace it to this canonical situation,
> For standard test/boxmodels/1p problem, if I increase the 2D grid resolution
> from 10x10 to 100x100, the solver will not converge, with the following error
> reported.
>
> This error, however, will go away if I reduce the perm difference between
> lens and exterior from 2 order of magnitude into 1 order of magnitude. This
> makes me speculate that the error is related to sharp gradient at
> lens/exterior interface caused by the heterogeneity at high resolution.
>
> I think the reproducer on standard test makes it likely a serious problem,
> though I will be very happily corrected.
>
> Truly appreciate your quick attention.
>
> Best,
> -Shawn
>
> root@szdebian:/home/szhang/dumux/dumux-2.1.0/test/boxmodels/1p# ./test_1p
> -parameterFile test_1p.input
> Welcome aboard DuMuX airlines. Please fasten your seatbelts! Emergency exits
> are near the time integration.
> Initializing problem '1ptest'
> Writing result file for "1ptest"
> Newton iteration 1 done, relative error = 0.666666
> Newton iteration 2 done, relative error = 5.45083e-06
> Solve: M deltax^k = rNewton: Caught exception: "NumericalProblem
> [newtonSolveLinear:../../../dumux/nonlinear/newtoncontroller.hh:398]: Linear
> solver did not converge"
> Newton solver did not converge with dt=1 seconds. Retrying with time step of
> 0.5 seconds
> Newton iteration 1 done, relative error = 0.666666
> Newton iteration 2 done, relative error = 5.45083e-06
> Solve: M deltax^k = rNewton: Caught exception: "NumericalProblem
> [newtonSolveLinear:../../../dumux/nonlinear/newtoncontroller.hh:398]: Linear
> solver did not converge"
>
> ....
> Newton solver did not converge with dt=0.0078125 seconds. Retrying with time
> step of 0.00390625 seconds
> Newton iteration 1 done, relative error = 0.666666
> Newton iteration 2 done, relative error = 5.45083e-06
> Solve: M deltax^k = rNewton: Caught exception: "NumericalProblem
> [newtonSolveLinear:../../../dumux/nonlinear/newtoncontroller.hh:398]: Linear
> solver did not converge"
> Newton solver did not converge with dt=0.00390625 seconds. Retrying with time
> step of 0.00195312 seconds
> Newton iteration 1 done, relative error = 0.666666
> Newton iteration 2 done, relative error = 5.45083e-06
> Solve: M deltax^k = rNewton: Caught exception: "NumericalProblem
> [newtonSolveLinear:../../../dumux/nonlinear/newtoncontroller.hh:398]: Linear
> solver did not converge"
> Newton solver did not converge with dt=0.00195312 seconds. Retrying with time
> step of 0.000976562 seconds
> Dune reported error: Dune::MathError
> [timeIntegration:../../../dumux/boxmodels/common/boxproblem.hh:485]: Newton
> solver didn't converge after 10 time-step divisions. dt=0.000976562
___________________________________________________________
Bernd Flemisch phone: +49 711 685 69162
IWS, Universitaet Stuttgart fax: +49 711 685 67020
Pfaffenwaldring 61 email: [email protected]
D-70569 Stuttgart url: www.hydrosys.uni-stuttgart.de
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