Dear DuMux developers,
With my colleagues we are working on two-phase multicomponent flow with
reactive transport and application to CO2 storage.
The problem is decoupled into two subproblems. The first one is devoted
to a two-phase two-component flow (H2O-CO2) while the second one is
devoted to a one-phase multicomponent reactive transport problem for the
other components.
We have successfully performed sequential simulations. No we would like
to perform parallel computations but we have some difficulties to chose
. In a previous mail, Bernd told to a DUMUX user that for your parallel
computations, you used AMG solver. Consequently we performed some tests
to compare the performances of the AMG solver in comparison with the
solver by default and we found a strange behaviour.
To explain our problem, we have installed the last version 2.6 of DUMUX.
We use the CO2 model on a 3D mesh (80000 elements). The problem deals
with injection of CO2. We use ALUGRID for the mesh. We want to do only
one iteration (DtInitial = 86400, TEnd = 86400) and compare the time of
simulation on 1, 2, 4, 8,... processors. The times of simulation are
displayed below:
#procs bicg amg
1 212.089 315.145
2 118.446 401.046
4 292.873 244.24
6 not done Stopped coarsening because of rate breakdown
For the bicg, with 4 processors, Newton solver does not converge with
Dt=86400 and the simulation needs 4 iterations to reach Tend so the
computation is slower than for one processor.
For the amg solver, the behaviour is even more strange since the
computations is faster with one processor than with two processors. With
6 processors, the computation stopped but I think that it is due to the
small size of our mesh.
We expected that the amg solver will be faster that the bicg but it is
not the case.
Have you already found the same behaviour with your simulation? Is it
normal in your opinion? Which solver do you advise us?
We have also seen in the mail announcing the DUMUX 2.6 release that a
new direct solver UMFPACK is available. We would like to know how it is
possible to test it.
Thanks in advance.
Best regards
Etienne
_______________________________________________
Dumux mailing list
[email protected]
https://listserv.uni-stuttgart.de/mailman/listinfo/dumux
