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May 22, 2017, 14:27 |
error, courant number goes up
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#1 |
New Member
Francisco Peņa Gallardo
Join Date: Jun 2016
Posts: 5
Rep Power: 10 |
Hello there, i have a terrible problem, it results that when i run a simulation with the app buoyantBoussinesq in my personal cumputer with 16 cores in openfoam 3.1 it goes well, but when i try to run the same app in a cluster in openfoam 3.2 the courant number goes up and the first iterations en it crashes, and i do not why it is happening , is the precompiled app in both versions, and i have tryed run a diferrent solver (a custom one) in the cluster with foam 3.2 and runs well as in my personal pc in foam 3.1, could someone help me plz ty
Code:
Time = 5400.0300000000007 Courant Number mean: 26.5121 max: 1666.96 velocity magnitude: 2966.55 DILUPBiCG: Solving for Ux, Initial residual = 0.911188, Final residual = 7.42636e-06, No Iterations 62 DILUPBiCG: Solving for Uy, Initial residual = 0.919441, Final residual = 9.4579e-06, No Iterations 55 DILUPBiCG: Solving for Uz, Initial residual = 0.941604, Final residual = 2.72516e+09, No Iterations 1000 DILUPBiCG: Solving for T, Initial residual = 0.998317, Final residual = 4.1805e-06, No Iterations 60 DICPCG: Solving for p, Initial residual = 1, Final residual = 0.0950819, No Iterations 9 time step continuity errors : sum local = 1.64311e+10, global = -662.716, cumulative = -662.716 DICPCG: Solving for p, Initial residual = 0.675918, Final residual = 9.89838e-08, No Iterations 240 time step continuity errors : sum local = 37805.4, global = -1002.59, cumulative = -1665.3 DILUPBiCG: Solving for epsilon, Initial residual = 1, Final residual = 9.35798e-06, No Iterations 84 DILUPBiCG: Solving for k, Initial residual = 1, Final residual = 1.12121e-06, No Iterations 15 bounding k, min: -3.27486e+06 max: 5.86224e+17 average: 5.59259e+13 ExecutionTime = 4.21 s ClockTime = 6 s Time = 5400.0350000000008 Courant Number mean: 2.457e+11 max: 4.17318e+15 velocity magnitude: 2.10058e+16 DILUPBiCG: Solving for Ux, Initial residual = 1, Final residual = 6.92186e-06, No Iterations 357 DILUPBiCG: Solving for Uy, Initial residual = 1, Final residual = 0.00108087, No Iterations 1000 DILUPBiCG: Solving for Uz, Initial residual = 1, Final residual = 4.36233e-06, No Iterations 397 DILUPBiCG: Solving for T, Initial residual = 1, Final residual = 0.0356456, No Iterations 1000 DICPCG: Solving for p, Initial residual = 1, Final residual = 0.0991199, No Iterations 137 time step continuity errors : sum local = 1.13764e+12, global = -4.05105e+06, cumulative = -4.05271e+06 DICPCG: Solving for p, Initial residual = 0.803679, Final residual = 46.9312, No Iterations 1000 time step continuity errors : sum local = 1.96568e+15, global = -1.13509e+08, cumulative = -1.17562e+08 DILUPBiCG: Solving for epsilon, Initial residual = 0.992903, Final residual = 1.99109e-06, No Iterations 20 bounding epsilon, min: -3.30441e+15 max: 7.96184e+26 average: 1.1842e+25 DILUPBiCG: Solving for k, Initial residual = 0.999995, Final residual = 3.99017e-06, No Iterations 13 bounding k, min: -1.24997e+14 max: 6.30641e+22 average: 1.19204e+20 |
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May 22, 2017, 17:21 |
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#2 |
Senior Member
matej forman
Join Date: Mar 2009
Location: Brno, Czech Republic
Posts: 182
Rep Power: 17 |
Just to make sure, you have exactly the same settings and on a case where it runs your Co_max looks reasonable not like in the log you posted, right?
Then your Initial condition and your numerical setup is very fragile and such a thing like run on a different system with different decomposition could be behind the problem. So I would try to: limit gradients for velocity and k and epsilon with cellLimitation. You can switch to upwinding everything at the beginning to see any difference in behaviour. Maybe use to power of PIMPLE algorithm and increase the outer correctors to 2? |
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May 25, 2017, 00:58 |
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#3 |
Senior Member
Svetlana Tkachenko
Join Date: Oct 2013
Location: Australia, Sydney
Posts: 415
Rep Power: 14 |
What matejfor said, or do you have an opportunity to compile openfoam 3.1 on the cluster?
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Tags |
courant, courant number increasing, foam 3.1, foam 3.2 |
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