[ZX-zha]

Hello, everyone!
I wrote a drag model, and i want to write the calculated coefficient to the file like the velocity or pressure file does.
So I wrote down:

    volScalarField KD
    (
        IOobject
        (
            "KD",
            mesh.time().timeName(),
            mesh,
            IOobject::NO_READ,
            IOobject::MUST_WRITE
        ),
        mesh,
        dimensionedScalar("zero",dimDensity*dimLength*dimVelocity/dimArea,0.0),
        relativeHeight_.boundaryField().types()
    );

But it dsn't work, what should i do?

[saeed jamshidi]

Hi ZX-zha,

I think you should give us more information about your procedures!!!
Make it more clear.

[ZX-zha]

Hello, saeed jamshidi:
More specifically, I want to export the drag coefficient to a file in each time step like the ordinary variables p or U.
But i don't know how to get the drag coefficient in the program. Can anyone help me?

[saeed jamshidi]

simply add the attached file into your system folder, and call it in controlDict/function as below:

functions
{

    #include "forceCoeffs"

}

care about format of forceCoeffs.txt

next, adapt contents of the forceCoeffs based on your problem.

this will create postprocess folder, which contains drag and lift data.

If you have any further question, please let me know.

Best,
Saeed

[ZX-zha]

Thank you very much for your advice. That helped a lot.