pisoFoam gets stuck with no error and little cournant number

XJ_Wang · April 4, 2020, 02:38

Dear Foamers,

I am running a pisoFoam in a cluster.

At the first stage, I tried running it in one node with 16 processors. It goes well but a little slowly. The time step is 0.001s and finally, I got a 3.6s data in 12 hours. Then I terminated it. There are 5.6M cells.

Then I tried to run it in 16 nodes with 256 processors in total to speed up. It was indeed faster than before, but it was stuck at 0.162s for once and 0.17s for another time.

The same situation happened when I used 8 nodes with 128 processors.

The courant number is 0.225 with the maximum is 0.315 before it got stuck. I am using a pisoFoam solver and a synthetic method to generate the inflow boundary condition.

I think it might also get stuck when I run it in one node.

Code:

Time = 0.168

Courant Number mean: 0.2252957 max: 0.3151702
Patch: inlet recycled 3 eddies
mass flow correction coefficient: 1.005238
smoothSolver:  Solving for Ux, Initial residual = 0.005431484, Final residual = 3.443522e-07, No Iterations 4
smoothSolver:  Solving for Uz, Initial residual = 0.00986471, Final residual = 6.099746e-07, No Iterations 4
GAMG:  Solving for p, Initial residual = 0.1917015, Final residual = 0.01027828, No Iterations 2
time step continuity errors : sum local = 8.542895e-07, global = 6.909716e-10, cumulative = -8.085466e-07
GAMG:  Solving for p, Initial residual = 0.01235708, Final residual = 8.729178e-07, No Iterations 21
time step continuity errors : sum local = 7.655085e-11, global = -5.037762e-13, cumulative = -8.085471e-07
ExecutionTime = 440.13 s  ClockTime = 426 s

Time = 0.169

Courant Number mean: 0.2252872 max: 0.3151045
Patch: inlet recycled 4 eddies
mass flow correction coefficient: 1.005221
smoothSolver:  Solving for Ux, Initial residual = 0.004916222, Final residual = 3.063116e-07, No Iterations 4
smoothSolver:  Solving for Uz, Initial residual = 0.009755776, Final residual = 6.022459e-07, No Iterations 4
GAMG:  Solving for p, Initial residual = 0.1274995, Final residual = 0.008578488, No Iterations 2
time step continuity errors : sum local = 7.616146e-07, global = -1.088968e-10, cumulative = -8.08656e-07
GAMG:  Solving for p, Initial residual = 0.009608369, Final residual = 8.486479e-07, No Iterations 21
time step continuity errors : sum local = 7.726608e-11, global = 7.693458e-13, cumulative = -8.086552e-07
ExecutionTime = 442.66 s  ClockTime = 429 s

Time = 0.17

Courant Number mean: 0.2252813 max: 0.3153122
Patch: inlet recycled 7 eddies
mass flow correction coefficient: 1.00542

Does anyone have any suggestions?

I would really appreciate it if you can give me some suggestions!

Bests,
Xiangjie

XJ_Wang · April 4, 2020, 03:04

I forgot to mention that I tried to delete the latest time step file and run pisoFoam again starting from the latest time step, like in this case I deleted the file 0.17 and ran pisoFoam from 0.169, then it can run for a while but will still get stuck at some time step later.

Quote:

Originally Posted by XJ_Wang

Dear Foamers,

I am running a pisoFoam in a cluster.

At the first stage, I tried running it in one node with 16 processors. It goes well but a little slowly. The time step is 0.001s and finally, I got a 3.6s data in 12 hours. Then I terminated it. There are 5.6M cells.

Then I tried to run it in 16 nodes with 256 processors in total to speed up. It was indeed faster than before, but it was stuck at 0.162s for once and 0.17s for another time.

The same situation happened when I used 8 nodes with 128 processors.

The courant number is 0.225 with the maximum is 0.315 before it got stuck. I am using a pisoFoam solver and a synthetic method to generate the inflow boundary condition.

I think it might also get stuck when I run it in one node.

Code:

Time = 0.168

Courant Number mean: 0.2252957 max: 0.3151702
Patch: inlet recycled 3 eddies
mass flow correction coefficient: 1.005238
smoothSolver:  Solving for Ux, Initial residual = 0.005431484, Final residual = 3.443522e-07, No Iterations 4
smoothSolver:  Solving for Uz, Initial residual = 0.00986471, Final residual = 6.099746e-07, No Iterations 4
GAMG:  Solving for p, Initial residual = 0.1917015, Final residual = 0.01027828, No Iterations 2
time step continuity errors : sum local = 8.542895e-07, global = 6.909716e-10, cumulative = -8.085466e-07
GAMG:  Solving for p, Initial residual = 0.01235708, Final residual = 8.729178e-07, No Iterations 21
time step continuity errors : sum local = 7.655085e-11, global = -5.037762e-13, cumulative = -8.085471e-07
ExecutionTime = 440.13 s  ClockTime = 426 s

Time = 0.169

Courant Number mean: 0.2252872 max: 0.3151045
Patch: inlet recycled 4 eddies
mass flow correction coefficient: 1.005221
smoothSolver:  Solving for Ux, Initial residual = 0.004916222, Final residual = 3.063116e-07, No Iterations 4
smoothSolver:  Solving for Uz, Initial residual = 0.009755776, Final residual = 6.022459e-07, No Iterations 4
GAMG:  Solving for p, Initial residual = 0.1274995, Final residual = 0.008578488, No Iterations 2
time step continuity errors : sum local = 7.616146e-07, global = -1.088968e-10, cumulative = -8.08656e-07
GAMG:  Solving for p, Initial residual = 0.009608369, Final residual = 8.486479e-07, No Iterations 21
time step continuity errors : sum local = 7.726608e-11, global = 7.693458e-13, cumulative = -8.086552e-07
ExecutionTime = 442.66 s  ClockTime = 429 s

Time = 0.17

Courant Number mean: 0.2252813 max: 0.3153122
Patch: inlet recycled 7 eddies
mass flow correction coefficient: 1.00542

Does anyone have any suggestions?

I would really appreciate it if you can give me some suggestions!

Bests,
Xiangjie