[backscatter]

Modifying pimpleFoam, I've created a dimensionedScalar which which computes the area weighted average over the boundary patches 'INLET' and 'OUTLET'. In createFields.H, I add the following entries to create the dimensionedScalar 'meanTOut' and 'meanTIn' (which are avg. temperatures on outlet and inlet patch respectively):

dimensionedScalar meanTOut     // used in TEqn.H
(
    "meanTOut",
    dimensionSet(0, 0, 0, 1, 0, 0 ,0),
    1 // initilization
);

dimensionedScalar meanTIn     // used in TEqn.H
(
    "meanTIn",
    dimensionSet(0, 0, 0, 1, 0, 0 ,0),
    0 // initilization
);

Then in TEqn.H, I add the following loop to compute the area weighted mean temperatures on these patches during every iteration:

// Area-weighted Temperature on OUTLET patch
    if (areaOut > 0)
    {
    dimensionedScalar meanTOut = gSum
    (
    mesh.magSf().boundaryField()[OUTLET]
    * T.boundaryField()[OUTLET]
    )/ areaOut;
    }

// Area-weighted Temperature on INLET patch
    if (areaIn > 0)
    {
    dimensionedScalar meanTIn = gSum
    (
    mesh.magSf().boundaryField()[INLET]
    * T.boundaryField()[INLET]
    )/ areaIn;
    }

     Info<< "Area weighted OUTLET patch temperature = " << meanTOut << nl << endl;
     Info<< "Area weighted INLET patch temperature = = " << meanTIn << nl << endl;

But when I run the solver on channel flow case, it doesn't update the 'meanTOut' and 'meanTIn' as per the loops given above. Instead, 'meanTOut' and 'meanTIn' are stuck at their initial values of "1" and "0" as initialized in createFields.H.


Am I missing anything basic here?

Anyhelp is appreciated.



PS: The other variables like areaIn, areaOut & patch labels like INLET and OUTLET etc. have been calculated elsewhere not shown in the code above.

[tomf]

Hi,

You may need to modify the code for some reason, but if you need to find the average of a field on a patch, there is already a functionObject:

surfaceFieldValue.

Depending on the version you use it may be called differently.
Regards,
Tom

[snak]

Hi,halo


Why do you define the "meanTout" twice?

If you define meanTout as dimensionedScalar in createFields.H,
there will be no need for defining it again in if{}.


Probably you are creating two different "meanTout" instances with a same name in the different scopes.
The values of meanTout inside if{} will be calculated. But, what you write out is not that one.