Monitoring Courant Number

Mahe88 · November 17, 2016, 10:56

Hello,

I'm setting up a Simulation and I want to use adjustable Time Step with a maxCo of 0.9.
Unfortunately when I log my Simulation it doesn't even show me the Courant Number.

Can somebody please look over my Control Dict and give me a hint? I am using OF v3.

Code:

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  4.1                                   |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    location    "system";
    object      controlDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

application     simpleFoam;

startFrom       latestTime;

//startTime       0;

stopAt          endTime;

endTime         52;

deltaT          0.001;

writeControl    adjustableRunTime;

writeInterval   100;

purgeWrite      0;

writeFormat     ascii;

writePrecision  6;

writeCompression off;

timeFormat      general;

timePrecision   6;

runTimeModifiable yes;

adjustTimeStep    yes;

maxCo        0.9;

maxDeltaT    2;



 functions
{
    #include "forceCoeffs"
}
// ************************************************************************* //

floquation · November 17, 2016, 12:39

Co is always printed to stdout.
So how did you "log your simulation"? What is the output?

elones · November 17, 2016, 12:44

What solver are you using? If simpleFoam or any other steady state solver, CFL number is meaningless in those solvers and hence not computed.

Mahe88 · November 17, 2016, 15:12

Thanks for your replies!

I use simpleFoam > log

For initializiation I use potentialFoam and switch then to simpleFoam. Didn't know the Courant number ist then meaningless. Thanks for the information

I want to simulate the lift and drag coefficient od an airfoil. Is it Ok to use SimpleFoam or should I use a different solver?

My log file looks like this:

Code:

/*---------------------------------------------------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  3.0.1                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
Build  : 3.0.1-119cac7e8750
Exec   : simpleFoam
Date   : Nov 17 2016
Time   : 15:18:48

PID    : 28855
Case   : /home/projects/OpenFOAM/projects-4.1/run/TL181/Octave/Mesh_jeder_punkt/TL181_Ref
nProcs : 1
sigFpe : Enabling floating point exception trapping (FOAM_SIGFPE).
fileModificationChecking : Monitoring run-time modified files using timeStampMaster
allowSystemOperations : Allowing user-supplied system call operations

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
Create time

Create mesh for time = 25


SIMPLE: convergence criteria
    field p	 tolerance 1e-05
    field U	 tolerance 1e-05
    field nuTilda	 tolerance 1e-05

Reading field p

Reading field U

Reading/calculating face flux field phi

Selecting incompressible transport model Newtonian
Selecting turbulence model type RAS
Selecting RAS turbulence model kOmegaSST
Selecting patchDistMethod meshWave
kOmegaSSTCoeffs
{
    alphaK1         0.85;
    alphaK2         1;
    alphaOmega1     0.5;
    alphaOmega2     0.856;
    gamma1          0.555556;
    gamma2          0.44;
    beta1           0.075;
    beta2           0.0828;
    betaStar        0.09;
    a1              0.31;
    b1              1;
    c1              10;
    F3              false;
}

No MRF models present

No finite volume options present


Starting time loop

forces forces:
    Not including porosity effects

forceCoeffs forceCoeffs:
    Not including porosity effects

Time = 25.1

DILUPBiCG:  Solving for Ux, Initial residual = 0.00174067, Final residual = 4.91275e-05, No Iterations 1
DILUPBiCG:  Solving for Uy, Initial residual = 0.00141275, Final residual = 1.20297e-05, No Iterations 2
DICPCG:  Solving for p, Initial residual = 0.0288016, Final residual = 0.00241564, No Iterations 5
DICPCG:  Solving for p, Initial residual = 0.00231823, Final residual = 0.000219713, No Iterations 53
time step continuity errors : sum local = 6.21274e-08, global = 2.59655e-09, cumulative = 2.59655e-09
DILUPBiCG:  Solving for omega, Initial residual = 0.00011992, Final residual = 2.86982e-06, No Iterations 1
bounding omega, min: -7.97477 max: 42322.1 average: 118.323
DILUPBiCG:  Solving for k, Initial residual = 0.000578196, Final residual = 2.3433e-05, No Iterations 1
ExecutionTime = 2.65 s  ClockTime = 3 s

forces forces output:
    sum of forces:
        pressure : (112.411 2299.91 6.90839e-18)
        viscous  : (38.0014 0.603502 -7.52174e-07)
        porous   : (0 0 0)
    sum of moments:
        pressure : (-1149.96 56.2055 1249.49)
        viscous  : (-0.301751 19.0007 -1.52337)
        porous   : (0 0 0)

forceCoeffs forceCoeffs output:
    Cm    = -0.070081
    Cd    = 0.0286327
    Cl    = 0.437928
    Cl(f) = 0.148883
    Cl(r) = 0.289045

Time = 25.2

DILUPBiCG:  Solving for Ux, Initial residual = 0.00167023, Final residual = 3.48027e-05, No Iterations 1
DILUPBiCG:  Solving for Uy, Initial residual = 0.00141697, Final residual = 1.21194e-05, No Iterations 2
DICPCG:  Solving for p, Initial residual = 0.00346322, Final residual = 0.000334259, No Iterations 46
DICPCG:  Solving for p, Initial residual = 0.00040158, Final residual = 3.79943e-05, No Iterations 154
time step continuity errors : sum local = 1.04057e-08, global = 3.5899e-10, cumulative = 2.95554e-09
DILUPBiCG:  Solving for omega, Initial residual = 0.000119388, Final residual = 2.9017e-06, No Iterations 1
bounding omega, min: -8.78932 max: 42324.6 average: 118.294
DILUPBiCG:  Solving for k, Initial residual = 0.000565306, Final residual = 2.1144e-05, No Iterations 1
ExecutionTime = 4.04 s  ClockTime = 4 s

forces forces output:
    sum of forces:
        pressure : (112.327 2301.64 6.90903e-18)
        viscous  : (38.0021 0.60481 -7.51672e-07)
        porous   : (0 0 0)
    sum of moments:
        pressure : (-1150.82 56.1634 1250.05)
        viscous  : (-0.302405 19.0011 -1.52368)
        porous   : (0 0 0)

forceCoeffs forceCoeffs output:
    Cm    = -0.0702054
    Cd    = 0.0286168
    Cl    = 0.438258
    Cl(f) = 0.148923
    Cl(r) = 0.289334

Time = 25.3

DILUPBiCG:  Solving for Ux, Initial residual = 0.00152759, Final residual = 3.60164e-05, No Iterations 1
DILUPBiCG:  Solving for Uy, Initial residual = 0.00142068, Final residual = 1.21072e-05, No Iterations 2
DICPCG:  Solving for p, Initial residual = 0.00819921, Final residual = 0.000812361, No Iterations 14
DICPCG:  Solving for p, Initial residual = 0.000892064, Final residual = 8.78842e-05, No Iterations 90
time step continuity errors : sum local = 2.40244e-08, global = 2.40198e-09, cumulative = 5.35752e-09
DILUPBiCG:  Solving for omega, Initial residual = 0.000117772, Final residual = 2.80057e-06, No Iterations 1
bounding omega, min: -7.77123 max: 42327 average: 118.264
DILUPBiCG:  Solving for k, Initial residual = 0.000547935, Final residual = 2.03778e-05, No Iterations 1
ExecutionTime = 5.01 s  ClockTime = 5 s

forces forces output:
    sum of forces:
        pressure : (112.238 2303.38 6.90765e-18)
        viscous  : (38.0028 0.606146 -7.49902e-07)
        porous   : (0 0 0)
    sum of moments:
        pressure : (-1151.69 56.119 1250.62)
        viscous  : (-0.303073 19.0014 -1.52396)
        porous   : (0 0 0)

forceCoeffs forceCoeffs output:
    Cm    = -0.0703305
    Cd    = 0.0286
    Cl    = 0.43859
    Cl(f) = 0.148964
    Cl(r) = 0.289625

Time = 25.4

DILUPBiCG:  Solving for Ux, Initial residual = 0.00151054, Final residual = 3.50836e-05, No Iterations 1
DILUPBiCG:  Solving for Uy, Initial residual = 0.00142477, Final residual = 1.20519e-05, No Iterations 2
DICPCG:  Solving for p, Initial residual = 0.0069368, Final residual = 0.000651817, No Iterations 18
DICPCG:  Solving for p, Initial residual = 0.00072115, Final residual = 7.17011e-05, No Iterations 115
time step continuity errors : sum local = 1.9613e-08, global = 1.30735e-09, cumulative = 6.66487e-09
DILUPBiCG:  Solving for omega, Initial residual = 0.000121844, Final residual = 2.87799e-06, No Iterations 1
bounding omega, min: -8.58395 max: 42329.4 average: 118.235
DILUPBiCG:  Solving for k, Initial residual = 0.000574125, Final residual = 2.23356e-05, No Iterations 1
ExecutionTime = 6.12 s  ClockTime = 6 s

forces forces output:
    sum of forces:
        pressure : (112.159 2304.91 6.9047e-18)
        viscous  : (38.0034 0.607468 -7.49192e-07)
        porous   : (0 0 0)
    sum of moments:
        pressure : (-1152.46 56.0797 1251.05)
        viscous  : (-0.303734 19.0017 -1.52425)
        porous   : (0 0 0)

forceCoeffs forceCoeffs output:
    Cm    = -0.0704536
    Cd    = 0.0285852
    Cl    = 0.438881
    Cl(f) = 0.148987
    Cl(r) = 0.289894

Time = 25.5

DILUPBiCG:  Solving for Ux, Initial residual = 0.00150688, Final residual = 3.36634e-05, No Iterations 1
DILUPBiCG:  Solving for Uy, Initial residual = 0.0014296, Final residual = 1.20479e-05, No Iterations 2
DICPCG:  Solving for p, Initial residual = 0.00515886, Final residual = 0.00049919, No Iterations 22
DICPCG:  Solving for p, Initial residual = 0.000562578, Final residual = 5.40334e-05, No Iterations 142
time step continuity errors : sum local = 1.47812e-08, global = 7.614e-10, cumulative = 7.42627e-09
DILUPBiCG:  Solving for omega, Initial residual = 0.000114387, Final residual = 2.86901e-06, No Iterations 1
bounding omega, min: -7.37622 max: 42331.8 average: 118.205
DILUPBiCG:  Solving for k, Initial residual = 0.000540268, Final residual = 2.01231e-05, No Iterations 1
ExecutionTime = 7.3 s  ClockTime = 7 s

forces forces output:
    sum of forces:
        pressure : (112.079 2306.32 6.90167e-18)
        viscous  : (38.0041 0.60878 -7.49217e-07)
        porous   : (0 0 0)
    sum of moments:
        pressure : (-1153.16 56.0397 1251.41)
        viscous  : (-0.30439 19.0021 -1.52454)
        porous   : (0 0 0)

forceCoeffs forceCoeffs output:
    Cm    = -0.0705719
    Cd    = 0.0285701
    Cl    = 0.439149
    Cl(f) = 0.149002
    Cl(r) = 0.290146

November 17, 2016, 12:44		#3
elones New Member Join Date: Mar 2014 Location: Czech Republic Posts: 29 Rep Power: 14	What solver are you using? If simpleFoam or any other steady state solver, CFL number is meaningless in those solvers and hence not computed. openThanos and wht like this.

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November 17, 2016, 12:39		#2
floquation Senior Member Kevin van As Join Date: Sep 2014 Location: TU Delft, The Netherlands Posts: 252 Rep Power: 21	Co is always printed to stdout. So how did you "log your simulation"? What is the output?