CFD Online Discussion Forums - Average of Uprime2Mean(Reynolds stresses) in time and Uprime3mean definition

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Average of Uprime2Mean(Reynolds stresses) in time and Uprime3mean definition

Hello all
I want to average prime2Mean in time. There must be two options;
1- Adding new volScalarfield named RXX,RYY,RZZ,.... an then average in time(This should work fine)
2- Since we have generated Uprime2Mean already in U section, we may average it as a new parameter again without adding RXX,RYY,RZZ,.... .

Also I want to define Uprime3mean which is the third moment of velocity. I believe it must be defined in "libfieldFunctionObjects.so", but I can find the file to define this new parameter.

Do you have any suggestion for my questions?

Code:

/*--------------------------------*- C++ -*----------------------------------*\

  =========                 |

  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox

   \\    /   O peration     | Website:  https://openfoam.org

    \\  /    A nd           | Version:  6

     \\/     M anipulation  |

\*---------------------------------------------------------------------------*/

FoamFile

{

    version     2.0;

    format      ascii;

    class       dictionary;

    location    "system";

    object      controlDict;

}

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



application     pimpleFoam;



startFrom       latestTime;



startTime       0;



stopAt          endTime;



endTime         20;



deltaT          0.2;



writeControl    timeStep;



writeInterval   10;



purgeWrite      0;



writeFormat     ascii;



writePrecision  6;



writeCompression off;



timeFormat      general;



timePrecision   6;



runTimeModifiable true;



functions

{

    fieldAverage1

    {

        type            fieldAverage;

        libs            ("libfieldFunctionObjects.so");

        writeControl    writeTime;



        fields

        (

            U

            {

                mean        on;

                prime2Mean  on;

                base        time;

            }



        );

    }



}



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

Hi,
uprime2Mean is already averaged in time. why do you want to average again?

You are right, it is already averaged. What about Uprime3mean? Where is the function object file so I can modify it?

Thanks,
Farzad

Quote:

Originally Posted by aghsin (Post 833035)

Hi,
uprime2Mean is already averaged in time. why do you want to average again?

Quote:

Originally Posted by farzadmech (Post 833050)

You are right, it is already averaged. What about Uprime3mean? Where is the function object file so I can modify it?

Thanks,
Farzad

Do you mean a rank 3 tensor? I saw something about that a long time ago (at least in the programming guide they are mentioned) in the code, but it was not implemented or I never knew how to use it.

I want R111,R222,R333 and etc.

Farzad

Quote:

Originally Posted by agustinvo (Post 833064)

Do you mean a rank 3 tensor? I saw something about that a long time ago (at least in the programming guide they are mentioned) in the code, but it was not implemented or I never knew how to use it.

My main question is that where is Reynolds stresses defined? I found libfieldFunctionObjects but I did not see where Reynolds stresses has been defined. I want to add my definition there.

Thanks,
Farzad

Quote:

Originally Posted by farzadmech (Post 833071)

I want R111,R222,R333 and etc.

Farzad

The Reynolds stress tendor is defined in the turbulence model library. If you are using a eddy viscosity model R is not callable unless you use the turbulenceFields functioObject. If you are using a Reynolds stress model you would have no problems.

The problem you might have when computing the UPrime3Mean is that there are no rank three volFields. You should somehow load U and UMean and define your third momentum tensor instantaneously, but you should create three tensor fields and average them in time. Check the fieldAverage function to help you with that.