Why is pimpleFoam not stopping when desired residual is reached?

Illmatic · March 8, 2020, 13:47

Hi,

I am trying to use the residual control feature of pimpleFoam. To do so I set my nOuterCorrectors to a large number (50) and added a residualControl dictionary to the PIMPLE dictionary.

However for some reason pimpleFoam runs all 50 outer corrector loops instead of stopping earlier when reaching the residuals that are specified in residualControl

Code:

PIMPLE: Iteration 49
smoothSolver:  Solving for Ux, Initial residual = 1.7138e-09, Final residual = 1.7138e-09, No Iterations 0
smoothSolver:  Solving for Uy, Initial residual = 1.23965e-10, Final residual = 1.23965e-10, No Iterations 0
smoothSolver:  Solving for Uz, Initial residual = 3.13221e-10, Final residual = 3.13221e-10, No Iterations 0
GAMG:  Solving for p, Initial residual = 2.92413e-07, Final residual = 2.11863e-09, No Iterations 4
time step continuity errors : sum local = 7.28902e-14, global = -1.81969e-14, cumulative = 7.11654e-08
GAMG:  Solving for p, Initial residual = 2.05131e-07, Final residual = 2.05131e-07, No Iterations 0
time step continuity errors : sum local = 7.05742e-12, global = -4.9383e-14, cumulative = 7.11653e-08
PIMPLE: Iteration 50
smoothSolver:  Solving for Ux, Initial residual = 2.20554e-09, Final residual = 2.20554e-09, No Iterations 0
smoothSolver:  Solving for Uy, Initial residual = 1.588e-10, Final residual = 1.588e-10, No Iterations 0
smoothSolver:  Solving for Uz, Initial residual = 4.01691e-10, Final residual = 4.01691e-10, No Iterations 0
GAMG:  Solving for p, Initial residual = 0.897462, Final residual = 0.0052241, No Iterations 3
time step continuity errors : sum local = 1.35599e-07, global = -8.79393e-10, cumulative = 7.02859e-08
GAMG:  Solving for p, Initial residual = 0.0628147, Final residual = 9.87277e-07, No Iterations 13
time step continuity errors : sum local = 2.82111e-12, global = -4.26893e-13, cumulative = 7.02855e-08
ExecutionTime = 7084.84 s  ClockTime = 7196 s

Courant Number mean: 0.0100155 max: 1.21183
deltaT = 0.002
Time = 0.078

The complete fvSolution file looks like this:

Code:

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  4.x                                   |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      fvSolution;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

solvers
{
    pcorrFinal
    {
    solver GAMG;
    tolerance 0.02;
    relTol 0;
    smoother GaussSeidel;
    nPreSweeps 0;
    nPostSweeps 2;
    cacheAgglomeration no;
    nCellsInCoarsestLevel 10;
    agglomerator faceAreaPair;
    mergeLevels 1;
    }

    p
    {
    solver GAMG;
    tolerance 0;
    relTol 0.01;
    smoother GaussSeidel;
    nPreSweeps 0;
    nPostSweeps 2;
    cacheAgglomeration no;
    nCellsInCoarsestLevel 10;
    agglomerator faceAreaPair;
    mergeLevels 1;
    }

    pFinal
    {
    $p;
    tolerance 1e-06;
    relTol 0;
    }

    U
    {
    solver smoothSolver;
    smoother symGaussSeidel;
    tolerance 1e-05;
    relTol 0.1;
    }

    "(U|k|omega)"
    {
        solver          smoothSolver;
        smoother        symGaussSeidel;
        tolerance       1e-06;
        relTol          0.1;
    }

    "(U|k|omega)Final"
    {
        $U;
        tolerance       1e-06;
        relTol          0;
    }

    cellDisplacement
    {
        solver          GAMG;
        tolerance       1e-5;
        relTol          0;
        smoother        GaussSeidel;
        cacheAgglomeration true;
        nCellsInCoarsestLevel 10;
        agglomerator    faceAreaPair;
        mergeLevels     1;
    }
}

PIMPLE
{
    correctPhi          no;
    nOuterCorrectors    50;
    nCorrectors         2;
    nNonOrthogonalCorrectors 0;
    residualControl
    {
        U   1e-5;
        p   1e-3;
    }
}

relaxationFactors
{
    fields
    {
        p               0.3;
        pFinal          1.0;
    }
    equations
    {
        "(U|k|S|omega)"   0.7;
        "(U|k|S|omega)Final" 1.0;
    }
}


// ************************************************************************* //

How can I make pimpleFoam stopping outer correctors when it reaches the specifed residuals instead of keep running until the maximum number of outer correctors is reached?

ybapat · March 9, 2020, 00:56

Pressure initial residual show large jump from 49 to 50th iteration. Is the trend same for previous iterations?

Illmatic · March 9, 2020, 12:01

Hi ybapat,

thanks for your reply! I didn't even notice this.

So if I look at a few loops then this jump seems only to appear in the last one. How can this be explained?

Code:

PIMPLE: Iteration 41
smoothSolver:  Solving for Ux, Initial residual = 4.09821e-09, Final residual = 4.09821e-09, No Iterations 0
smoothSolver:  Solving for Uy, Initial residual = 7.31785e-10, Final residual = 7.31785e-10, No Iterations 0
smoothSolver:  Solving for Uz, Initial residual = 7.09859e-10, Final residual = 7.09859e-10, No Iterations 0
GAMG:  Solving for p, Initial residual = 6.72052e-07, Final residual = 4.58509e-09, No Iterations 4
time step continuity errors : sum local = 1.18113e-13, global = -4.35361e-14, cumulative = 1.63738e-08
GAMG:  Solving for p, Initial residual = 4.70794e-07, Final residual = 4.70794e-07, No Iterations 0
time step continuity errors : sum local = 1.21277e-11, global = -9.16023e-14, cumulative = 1.63737e-08
PIMPLE: Iteration 42
smoothSolver:  Solving for Ux, Initial residual = 3.60249e-09, Final residual = 3.60249e-09, No Iterations 0
smoothSolver:  Solving for Uy, Initial residual = 6.5494e-10, Final residual = 6.5494e-10, No Iterations 0
smoothSolver:  Solving for Uz, Initial residual = 6.25585e-10, Final residual = 6.25585e-10, No Iterations 0
GAMG:  Solving for p, Initial residual = 6.08686e-07, Final residual = 4.15026e-09, No Iterations 4
time step continuity errors : sum local = 1.06911e-13, global = -3.89635e-14, cumulative = 1.63737e-08
GAMG:  Solving for p, Initial residual = 4.26422e-07, Final residual = 4.26422e-07, No Iterations 0
time step continuity errors : sum local = 1.09847e-11, global = -8.39604e-14, cumulative = 1.63736e-08
PIMPLE: Iteration 43
smoothSolver:  Solving for Ux, Initial residual = 3.17227e-09, Final residual = 3.17227e-09, No Iterations 0
smoothSolver:  Solving for Uy, Initial residual = 5.86625e-10, Final residual = 5.86625e-10, No Iterations 0
smoothSolver:  Solving for Uz, Initial residual = 5.51957e-10, Final residual = 5.51957e-10, No Iterations 0
GAMG:  Solving for p, Initial residual = 5.51378e-07, Final residual = 3.75597e-09, No Iterations 4
time step continuity errors : sum local = 9.67543e-14, global = -3.48606e-14, cumulative = 1.63735e-08
GAMG:  Solving for p, Initial residual = 3.86293e-07, Final residual = 3.86293e-07, No Iterations 0
time step continuity errors : sum local = 9.95097e-12, global = -7.68566e-14, cumulative = 1.63735e-08
PIMPLE: Iteration 44
smoothSolver:  Solving for Ux, Initial residual = 2.79689e-09, Final residual = 2.79689e-09, No Iterations 0
smoothSolver:  Solving for Uy, Initial residual = 5.25585e-10, Final residual = 5.25585e-10, No Iterations 0
smoothSolver:  Solving for Uz, Initial residual = 4.87377e-10, Final residual = 4.87377e-10, No Iterations 0
GAMG:  Solving for p, Initial residual = 4.99553e-07, Final residual = 3.39867e-09, No Iterations 4
time step continuity errors : sum local = 8.75501e-14, global = -3.11823e-14, cumulative = 1.63734e-08
GAMG:  Solving for p, Initial residual = 3.49997e-07, Final residual = 3.49997e-07, No Iterations 0
time step continuity errors : sum local = 9.01596e-12, global = -7.0269e-14, cumulative = 1.63734e-08
PIMPLE: Iteration 45
smoothSolver:  Solving for Ux, Initial residual = 2.46883e-09, Final residual = 2.46883e-09, No Iterations 0
smoothSolver:  Solving for Uy, Initial residual = 4.70952e-10, Final residual = 4.70952e-10, No Iterations 0
smoothSolver:  Solving for Uz, Initial residual = 4.30642e-10, Final residual = 4.30642e-10, No Iterations 0
GAMG:  Solving for p, Initial residual = 4.52814e-07, Final residual = 3.07493e-09, No Iterations 4
time step continuity errors : sum local = 7.92107e-14, global = -2.78865e-14, cumulative = 1.63733e-08
GAMG:  Solving for p, Initial residual = 3.17251e-07, Final residual = 3.17251e-07, No Iterations 0
time step continuity errors : sum local = 8.17242e-12, global = -6.41737e-14, cumulative = 1.63733e-08
PIMPLE: Iteration 46
smoothSolver:  Solving for Ux, Initial residual = 2.18214e-09, Final residual = 2.18214e-09, No Iterations 0
smoothSolver:  Solving for Uy, Initial residual = 4.22015e-10, Final residual = 4.22015e-10, No Iterations 0
smoothSolver:  Solving for Uz, Initial residual = 3.80768e-10, Final residual = 3.80768e-10, No Iterations 0
GAMG:  Solving for p, Initial residual = 4.10607e-07, Final residual = 2.7816e-09, No Iterations 4
time step continuity errors : sum local = 7.16544e-14, global = -2.49349e-14, cumulative = 1.63732e-08
GAMG:  Solving for p, Initial residual = 2.8769e-07, Final residual = 2.8769e-07, No Iterations 0
time step continuity errors : sum local = 7.41093e-12, global = -5.85452e-14, cumulative = 1.63732e-08
PIMPLE: Iteration 47
smoothSolver:  Solving for Ux, Initial residual = 1.93072e-09, Final residual = 1.93072e-09, No Iterations 0
smoothSolver:  Solving for Uy, Initial residual = 3.78169e-10, Final residual = 3.78169e-10, No Iterations 0
smoothSolver:  Solving for Uz, Initial residual = 3.36907e-10, Final residual = 3.36907e-10, No Iterations 0
GAMG:  Solving for p, Initial residual = 3.72391e-07, Final residual = 2.51584e-09, No Iterations 4
time step continuity errors : sum local = 6.48083e-14, global = -2.22925e-14, cumulative = 1.63732e-08
GAMG:  Solving for p, Initial residual = 2.60925e-07, Final residual = 2.60925e-07, No Iterations 0
time step continuity errors : sum local = 6.72146e-12, global = -5.33575e-14, cumulative = 1.63731e-08
PIMPLE: Iteration 48
smoothSolver:  Solving for Ux, Initial residual = 1.71012e-09, Final residual = 1.71012e-09, No Iterations 0
smoothSolver:  Solving for Uy, Initial residual = 3.38883e-10, Final residual = 3.38883e-10, No Iterations 0
smoothSolver:  Solving for Uz, Initial residual = 2.9831e-10, Final residual = 2.9831e-10, No Iterations 0
GAMG:  Solving for p, Initial residual = 3.37758e-07, Final residual = 2.27511e-09, No Iterations 4
time step continuity errors : sum local = 5.86071e-14, global = -1.99279e-14, cumulative = 1.63731e-08
GAMG:  Solving for p, Initial residual = 2.3667e-07, Final residual = 2.3667e-07, No Iterations 0
time step continuity errors : sum local = 6.09664e-12, global = -4.85844e-14, cumulative = 1.6373e-08
PIMPLE: Iteration 49
smoothSolver:  Solving for Ux, Initial residual = 1.5165e-09, Final residual = 1.5165e-09, No Iterations 0
smoothSolver:  Solving for Uy, Initial residual = 3.0368e-10, Final residual = 3.0368e-10, No Iterations 0
smoothSolver:  Solving for Uz, Initial residual = 2.64332e-10, Final residual = 2.64332e-10, No Iterations 0
GAMG:  Solving for p, Initial residual = 3.06366e-07, Final residual = 2.05708e-09, No Iterations 4
time step continuity errors : sum local = 5.29907e-14, global = -1.78126e-14, cumulative = 1.6373e-08
GAMG:  Solving for p, Initial residual = 2.14683e-07, Final residual = 2.14683e-07, No Iterations 0
time step continuity errors : sum local = 5.53027e-12, global = -4.41998e-14, cumulative = 1.6373e-08
PIMPLE: Iteration 50
smoothSolver:  Solving for Ux, Initial residual = 1.93382e-09, Final residual = 1.93382e-09, No Iterations 0
smoothSolver:  Solving for Uy, Initial residual = 3.89304e-10, Final residual = 3.89304e-10, No Iterations 0
smoothSolver:  Solving for Uz, Initial residual = 3.35584e-10, Final residual = 3.35584e-10, No Iterations 0
GAMG:  Solving for p, Initial residual = 0.930871, Final residual = 0.00720703, No Iterations 3
time step continuity errors : sum local = 1.38566e-07, global = -9.03646e-10, cumulative = 1.54693e-08
GAMG:  Solving for p, Initial residual = 0.100811, Final residual = 7.13608e-07, No Iterations 14
time step continuity errors : sum local = 1.19524e-12, global = -1.76552e-13, cumulative = 1.54692e-08
ExecutionTime = 3426.79 s  ClockTime = 3505 s

Courant Number mean: 0.00563426 max: 0.984294
deltaT = 0.0013125
Time = 0.0134375

ybapat · March 10, 2020, 00:11

Noticed that you are changing URF to 1.0 for final iteration. I do not think it is required. Regarding convergence it is not clear why loop is not stopping before.

Diro7 · March 10, 2020, 04:03

Hi Axel!

May not be resolving and I'm still trying to figure it out, but I recently noticed that PIMPLE dictionary in fvSolution in recent OF releases also accepts a different keyword, outerCorrectorResidualControl.

In OF6 you can find it used in the compressible/rhoPimpleFoam/RAS/angledDuct/ tutorial:

Code:

PIMPLE
{
    momentumPredictor   yes;
    transonic           no;
    nOuterCorrectors    50;
    nCorrectors         1;
    nNonOrthogonalCorrectors 0;
    consistent          yes;
    simpleRho           yes;

    pMaxFactor          1.5;
    pMinFactor          0.9;

    outerCorrectorResidualControl
    {
        "(U|k|epsilon)"
        {
            relTol          0;
            tolerance       0.0001;
        }
    }

    turbOnFinalIterOnly no;
}

My guess is that the residualControl keyword was changed at some time. Still not sure about what difference exists now between residualControl and outerCorrectorResidualControl, but you can try to have a look.

Hope it helps!

Andrea

Illmatic · March 10, 2020, 10:50

Hi Andrea,

yes, that solved the issue. Thank you! Using outerCorrectorResidualControl the loop is stopped as expected.

Code:

PIMPLE: Iteration 23
smoothSolver:  Solving for Ux, Initial residual = 1.82295e-05, Final residual = 8.33261e-14, No Iterations 1
smoothSolver:  Solving for Uy, Initial residual = 6.45035e-06, Final residual = 6.45035e-06, No Iterations 0
smoothSolver:  Solving for Uz, Initial residual = 3.31901e-06, Final residual = 3.31901e-06, No Iterations 0
GAMG:  Solving for p, Initial residual = 1.83423e-06, Final residual = 1.22556e-08, No Iterations 4
time step continuity errors : sum local = 1.18399e-12, global = -2.94581e-13, cumulative = -5.23841e-09
GAMG:  Solving for p, Initial residual = 1.28691e-06, Final residual = 1.29429e-07, No Iterations 1
time step continuity errors : sum local = 1.25039e-11, global = -1.27086e-12, cumulative = -5.23968e-09
PIMPLE: Iteration 24
smoothSolver:  Solving for Ux, Initial residual = 1.44058e-05, Final residual = 6.32736e-14, No Iterations 1
smoothSolver:  Solving for Uy, Initial residual = 4.70901e-06, Final residual = 4.70901e-06, No Iterations 0
smoothSolver:  Solving for Uz, Initial residual = 2.63949e-06, Final residual = 2.63949e-06, No Iterations 0
GAMG:  Solving for p, Initial residual = 1.275e-06, Final residual = 8.80647e-09, No Iterations 4
time step continuity errors : sum local = 8.50782e-13, global = -2.07543e-13, cumulative = -5.23989e-09
GAMG:  Solving for p, Initial residual = 8.94593e-07, Final residual = 8.94593e-07, No Iterations 0
time step continuity errors : sum local = 8.64257e-11, global = -1.82023e-12, cumulative = -5.24171e-09
PIMPLE: Iteration 25
smoothSolver:  Solving for Ux, Initial residual = 7.53999e-06, Final residual = 7.53999e-06, No Iterations 0
smoothSolver:  Solving for Uy, Initial residual = 2.29805e-06, Final residual = 2.29805e-06, No Iterations 0
smoothSolver:  Solving for Uz, Initial residual = 1.40777e-06, Final residual = 1.40777e-06, No Iterations 0
GAMG:  Solving for p, Initial residual = 1.14894e-06, Final residual = 7.73808e-09, No Iterations 4
time step continuity errors : sum local = 7.47566e-13, global = -1.81834e-13, cumulative = -5.24189e-09
GAMG:  Solving for p, Initial residual = 8.06083e-07, Final residual = 8.06083e-07, No Iterations 0
time step continuity errors : sum local = 7.78749e-11, global = -1.55066e-12, cumulative = -5.24344e-09
PIMPLE: Converged 
        Doing final iteration
PIMPLE: Iteration 26
smoothSolver:  Solving for Ux, Initial residual = 7.21982e-06, Final residual = 5.87077e-14, No Iterations 1
smoothSolver:  Solving for Uy, Initial residual = 2.06676e-06, Final residual = 2.38317e-15, No Iterations 1
smoothSolver:  Solving for Uz, Initial residual = 1.36745e-06, Final residual = 9.47398e-15, No Iterations 1
GAMG:  Solving for p, Initial residual = 0.00153052, Final residual = 1.2177e-05, No Iterations 3
time step continuity errors : sum local = 1.6783e-09, global = -1.30711e-11, cumulative = -5.25651e-09
GAMG:  Solving for p, Initial residual = 1.71743e-05, Final residual = 9.55375e-07, No Iterations 3
time step continuity errors : sum local = 1.31499e-10, global = -1.6181e-11, cumulative = -5.27269e-09
PIMPLE: Converged in 26 iterations
ExecutionTime = 57.25 s  ClockTime = 58 s

Courant Number mean: 6.00521e-05 max: 0.0158798
deltaT = 1.43712e-05
Time = 2.63616e-05

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March 9, 2020, 00:56		#2
ybapat Senior Member Yogesh Bapat Join Date: Oct 2010 Posts: 102 Rep Power: 16	Pressure initial residual show large jump from 49 to 50th iteration. Is the trend same for previous iterations?

March 10, 2020, 00:11		#4
ybapat Senior Member Yogesh Bapat Join Date: Oct 2010 Posts: 102 Rep Power: 16	Noticed that you are changing URF to 1.0 for final iteration. I do not think it is required. Regarding convergence it is not clear why loop is not stopping before.

March 10, 2020, 04:03		#5
Diro7 Member Andrea Di Ronco Join Date: Nov 2016 Location: Milano, Italy Posts: 57 Rep Power: 9	Hi Axel! May not be resolving and I'm still trying to figure it out, but I recently noticed that PIMPLE dictionary in fvSolution in recent OF releases also accepts a different keyword, outerCorrectorResidualControl. In OF6 you can find it used in the compressible/rhoPimpleFoam/RAS/angledDuct/ tutorial: Code: PIMPLE { momentumPredictor yes; transonic no; nOuterCorrectors 50; nCorrectors 1; nNonOrthogonalCorrectors 0; consistent yes; simpleRho yes; pMaxFactor 1.5; pMinFactor 0.9; outerCorrectorResidualControl { "(U\|k\|epsilon)" { relTol 0; tolerance 0.0001; } } turbOnFinalIterOnly no; } My guess is that the residualControl keyword was changed at some time. Still not sure about what difference exists now between residualControl and outerCorrectorResidualControl, but you can try to have a look. Hope it helps! Andrea