[akesm]

Hello
I am new to openFOAM, I have a question might seem trivial.

I want to output the maximum of a certain parameter (say magnitude of velocity in the whole domain) during my simulation for a couple of time steps, I do not know where should I write this couple of code lines? Should it be in a script and run together with the run case? and if so how?


Any suggestion codes for doing so is highly appreciated.

[alexeym]

Hi,

Is there a reason you do not want to use fieldMinMax function object? You can find example in header file $FOAM_SRC/functionObjects/field/fieldMinMax/fieldMinMax.H

[akesm]

Thanks so much for your reply. Actually, I looked at this, it's for scalar quantities, not for instance velocity. But also I do not know how to use that function object, shall use it in my control dict, or any other way of using it?

[alexeym]

Why you have decided it is for scalar quantities?

For variables with a rank greater than zero, either the min/max of
a component value or the magnitude is reported.

Yes, you add description of the function object to controlDict. Or you create description as a separate file and use #include entry in controlDict.

And there is even an example of controlDict in $FOAM_SRC/functionObjects/field/fieldMinMax.

[rhythm]

Hi,

For cases like that I usually just introduce an info statement somewhere in the time loop, such as is done in multiphase solvers.
Don't know if you wanted to have the values output into a separate file, if you do, then there must be some sort of function object that would do this sort of thing.

If you only wanted to probe the min/max values of the field/parameter, then info statement is good enough and of course if you wanted to see how it evolves over time, then you can always extract them (sed/grep/awk etc.) from the log file to do some post processing.

Here's an example from driftFluxFoam alphaEqn.H:

    Info<< "Phase-1 volume fraction = "
        << alpha1.weightedAverage(mesh.Vsc()).value()
        << "  Min(" << alpha1.name() << ") = " << min(alpha1).value()
        << "  Max(" << alpha1.name() << ") = " << max(alpha1).value()
        << endl;

Cheers,
Ben

[akesm]

Thanks for your reply,
I put the below code in the controlDict but I get the error "keyword field is not defined"

functions 
{ 
    fieldMinMax1
    { 
        type        fieldMinMax;
        libs ("libfieldFunctionObjects.so");
        ...
        write       yes;
        log         yes;
        location    yes;
        mode        magnitude;
        fields
        (
            U
        );
    }  
}

[alexeym]

...

in header file example means skipped content and should not be copied to controlDict. Currently due to this dots your controlDict is not read till the end, as a result keyword fields is missing.

[akesm]

oops, my mistake, thanks now it is working and printing the maximum and all its relevant info in a separate folder named as "postprocessing".