Hi Dmitry,
if I get it right, the problematic entries are the derivatives of the second phase's mass balance equation w.r.t. to the saturation at the own DOF. Could it be that you consider the another phase than the numerical derivative does? (e.g. Sw instead of Sn) I mean, which formulation are you using? pw-Sn or pn-Sw? Maybe just just need to consider the other phase's saturation in your analytical derivative? Best wishes Kilian ________________________________ Von: Dumux <dumux-boun...@listserv.uni-stuttgart.de> im Auftrag von Dmitry Pavlov <dmitry.pav...@outlook.com> Gesendet: Samstag, 4. April 2020 12:48 An: DuMuX User Forum Betreff: [DuMuX] DiffMethod::numeric and DiffMethod::analytic giving opposite signs in the Jacobian Hello, I just ran into a weird problem with DuMux 3.1. As I reported before, I was having trouble replacing the numeric derivatives with my own analytic ones. Now I made a very small and simplified example and made some debug printing to track down the issue. The problem being solved is 2p (TwoPIncompressibleLocalResidual), fully implicit scheme. The assembler is FVAssembler<TypeTag, DiffMethod::numeric>. The boundary conditions are: neumann (injection well), all Dirichlet (production well). No customary flux derivatives, no other fancy stuff. Here is the first output of the debug printing that I added into NewtonSolver::solveLinearSystem_: Jacobian [n=4,m=4,rowdim=8,coldim=8] row 0 5.20412e-12 -7.65000e+09 -5.10436e-12 0.00000e+00 . . . . row 1 2.43297e-09 6.50250e+09 -2.43297e-09 0.00000e+00 . . . . row 2 -5.10436e-12 0.00000e+00 1.02087e-11 -7.65000e+09 -5.10436e-12 0.00000e+00 . . row 3 -2.43297e-09 0.00000e+00 4.86593e-09 6.50250e+09 -2.43297e-09 0.00000e+00 . . row 4 . . -5.10436e-12 0.00000e+00 1.02087e-11 -7.65000e+09 -5.10436e-12 0.00000e+00 row 5 . . -2.43297e-09 0.00000e+00 4.86593e-09 6.50250e+09 -2.43297e-09 0.00000e+00 row 6 . . . . -5.10436e-12 0.00000e+00 1.53131e-11 -7.65000e+09 row 7 . . . . -2.43297e-09 0.00000e+00 7.29888e-09 6.50250e+09 residual [blocks=4,dimension=8] row 0 -2.17e-02 0.00e+00 0.00e+00 0.00e+00 0.00e+00 0.00e+00 1.02e-06 4.87e-04 And the simulation goes fine after that (more or less). And here is what the first debug output becomes when I use FVAssembler<TypeTag, DiffMethod::analytic> instead: Jacobian [n=4,m=4,rowdim=8,coldim=8] row 0 5.10435e-12 -7.65000e+09 -5.10435e-12 0.00000e+00 . . . . row 1 2.43296e-09 -6.50250e+09 -2.43296e-09 0.00000e+00 . . . . row 2 -5.10435e-12 0.00000e+00 1.02087e-11 -7.65000e+09 -5.10435e-12 0.00000e+00 . . row 3 -2.43296e-09 0.00000e+00 4.86593e-09 -6.50250e+09 -2.43296e-09 0.00000e+00 . . row 4 . . -5.10435e-12 0.00000e+00 1.02087e-11 -7.65000e+09 -5.10435e-12 0.00000e+00 row 5 . . -2.43296e-09 0.00000e+00 4.86593e-09 -6.50250e+09 -2.43296e-09 0.00000e+00 row 6 . . . . -5.10435e-12 0.00000e+00 1.53131e-11 -7.65000e+09 row 7 . . . . -2.43296e-09 0.00000e+00 7.29889e-09 -6.50250e+09 residual [blocks=4,dimension=8] row 0 -2.17e-02 0.00e+00 0.00e+00 0.00e+00 0.00e+00 0.00e+00 1.02e-06 4.87e-04 And the simulation stucks instantly. You see that the odd diagonal elements have the opposite signs as compared to the ones of the analytic Jacobian. Did I run into a bug? Did I misuse DuMux? I will appreciate any comments. Best regards, Dmitry _______________________________________________ Dumux mailing list Dumux@listserv.uni-stuttgart.de https://listserv.uni-stuttgart.de/mailman/listinfo/dumux
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