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  • #715

Closed
Open
Created Jan 24, 2018 by Admin@OpenFOAM-adminMaintainer

pimpleFoam in OF1612 shows same time step twice in log file

Hi,

I recently installed OF1612 on my Uni's cluster (Scientific Linux 6.9 (Carbon)) without sudo right. I have been testing it using a wavy channel flow case. I found out if I set the timePrecision and writePrecision to 6, same time step will appear twice in the log file and the probed data in postProcessing:

In log file:

Time = 11.0001

PIMPLE: iteration 1
DILUPBiCG:  Solving for Ux, Initial residual = 0.000628327, Final residual = 6.49228e-06, No Iterations 1
DILUPBiCG:  Solving for Uy, Initial residual = 0.00710122, Final residual = 7.02765e-06, No Iterations 4
DILUPBiCG:  Solving for Uz, Initial residual = 0.00741627, Final residual = 1.45782e-06, No Iterations 5
Pressure gradient source: uncorrected Ubar = 0.3, pressure gradient = 0.188916
DICPCG:  Solving for p, Initial residual = 0.198051, Final residual = 0.00192128, No Iterations 611
time step continuity errors : sum local = 2.37292e-07, global = -1.72581e-07, cumulative = -5.94041e-07
Pressure gradient source: uncorrected Ubar = 0.300001, pressure gradient = 0.147912
DICPCG:  Solving for p, Initial residual = 0.0992778, Final residual = 9.82839e-07, No Iterations 762
time step continuity errors : sum local = 1.72608e-07, global = -1.72581e-07, cumulative = -7.66622e-07
Pressure gradient source: uncorrected Ubar = 0.300002, pressure gradient = 0.141237
ExecutionTime = 52.3 s  ClockTime = 52 s

Courant Number mean: 0.0777575 max: 3.3662
Time = 11.0001

PIMPLE: iteration 1
DILUPBiCG:  Solving for Ux, Initial residual = 0.000555812, Final residual = 7.84982e-07, No Iterations 3
DILUPBiCG:  Solving for Uy, Initial residual = 0.00624087, Final residual = 2.50926e-07, No Iterations 4
DILUPBiCG:  Solving for Uz, Initial residual = 0.00659523, Final residual = 8.90043e-06, No Iterations 2
Pressure gradient source: uncorrected Ubar = 0.3, pressure gradient = 0.126081
DICPCG:  Solving for p, Initial residual = 0.137678, Final residual = 0.00136057, No Iterations 522
time step continuity errors : sum local = 1.76456e-07, global = -1.43068e-07, cumulative = -9.0969e-07
Pressure gradient source: uncorrected Ubar = 0.3, pressure gradient = 0.153548
DICPCG:  Solving for p, Initial residual = 0.0448662, Final residual = 9.80399e-07, No Iterations 680
time step continuity errors : sum local = 1.43092e-07, global = -1.43068e-07, cumulative = -1.05276e-06
Pressure gradient source: uncorrected Ubar = 0.299999, pressure gradient = 0.156989
ExecutionTime = 72.1 s  ClockTime = 72 s

Courant Number mean: 0.0777578 max: 4.50452
Time = 11.0002

PIMPLE: iteration 1
DILUPBiCG:  Solving for Ux, Initial residual = 0.000544009, Final residual = 3.90541e-06, No Iterations 1
DILUPBiCG:  Solving for Uy, Initial residual = 0.00601562, Final residual = 2.7355e-06, No Iterations 3
DILUPBiCG:  Solving for Uz, Initial residual = 0.00635443, Final residual = 5.66006e-06, No Iterations 3
Pressure gradient source: uncorrected Ubar = 0.3, pressure gradient = 0.158873
DICPCG:  Solving for p, Initial residual = 0.0671597, Final residual = 0.000644585, No Iterations 467
time step continuity errors : sum local = 1.35701e-07, global = -1.20709e-07, cumulative = -1.17347e-06
Pressure gradient source: uncorrected Ubar = 0.3, pressure gradient = 0.154128
DICPCG:  Solving for p, Initial residual = 0.0185901, Final residual = 9.677e-07, No Iterations 698
time step continuity errors : sum local = 1.20732e-07, global = -1.20709e-07, cumulative = -1.29418e-06
Pressure gradient source: uncorrected Ubar = 0.3, pressure gradient = 0.153915
ExecutionTime = 90.76 s  ClockTime = 91 s

Courant Number mean: 0.077758 max: 2.9458
Time = 11.0002

PIMPLE: iteration 1
DILUPBiCG:  Solving for Ux, Initial residual = 0.000541136, Final residual = 2.5145e-06, No Iterations 2
DILUPBiCG:  Solving for Uy, Initial residual = 0.00600186, Final residual = 5.11656e-06, No Iterations 2
DILUPBiCG:  Solving for Uz, Initial residual = 0.00634764, Final residual = 4.17754e-06, No Iterations 2
Pressure gradient source: uncorrected Ubar = 0.3, pressure gradient = 0.153745
DICPCG:  Solving for p, Initial residual = 0.0565432, Final residual = 0.000557925, No Iterations 528
time step continuity errors : sum local = 1.16266e-07, global = -1.03347e-07, cumulative = -1.39752e-06
Pressure gradient source: uncorrected Ubar = 0.3, pressure gradient = 0.152974
DICPCG:  Solving for p, Initial residual = 0.0136746, Final residual = 9.9346e-07, No Iterations 656
time step continuity errors : sum local = 1.03369e-07, global = -1.03347e-07, cumulative = -1.50087e-06
Pressure gradient source: uncorrected Ubar = 0.3, pressure gradient = 0.154393
ExecutionTime = 110.86 s  ClockTime = 111 s

Courant Number mean: 0.077758 max: 2.6735

and in probed data:

#      Probe             0             1 
#     Time
      11.2001             (0.346425 -0.0206927 -0.0443701)             (0.396648 -0.0308353 0.0045432) 
      11.2001             (0.346504 -0.0208275 -0.0438397)             (0.396732 -0.0307284 0.00444979)
      11.2002             (0.346596 -0.0209262 -0.0432698)             (0.39684 -0.030652 0.00439261)
      11.2002             (0.346701 -0.0209961 -0.0426602)             (0.396971 -0.0306104 0.00437403)

Changing the timePrecision and writePrecision from 6 to 7 solves the problem. But I think there is a bug as the precision should be increased automatically if the program senses above problem. This is what OF230 did, in a similar case in OF230 (the precisions were 6 as well), the log file showed following and the time step were displayed correctly:

--> FOAM Warning :
    From function Time::operator++()
    in file db/Time/Time.C at line 1055
    Increased the timePrecision from 6 to 7 to distinguish between timeNames at time 10.67 

However, I think there is also a bug in OF230, because although OF230 automatically increase the precision in log file, it's probed data still show the same time steps twice.

The above issues can be reproduced.

I have discussed above problem in cfd-online forum and people thought it may be a bug. The link of the thread is: https://www.cfd-online.com/Forums/openfoam-bugs/197814-pimplefoam-of1612-shows-same-time-step-twice-log-file.html

Please can you have an investigation and solve the problem.

Kind regards, Yeru

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