CFD Online Discussion Forums - Accessing transportProperties from coded functionObject

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Accessing transportProperties from coded functionObject

Hello to all,

I would like to create a custom functionObject to use in laplacianFoam.

For this purpose, I need the parameter DT in the dictionary transportProperties.

I have:

Code:

functions

{

    myCodedFunction

    {

        type coded;

        libs (utilityFunctionObjects);

        writeControl runTime;

        writeInterval $writeInterval;





        // Name of on-the-fly generated functionObject

        name test;

        

        codeWrite

        #{

            // Lookup for T

            const volScalarField& T = mesh().lookupObject<volScalarField>("T");



            // Gets the DT coefficient from 

          const dictionary& transportProperties = mesh().lookupObject<IOdictionary>

          (

             "transportProperties"

          );    



            const scalar alpha (transportProperties.getScalar("DT"));



            Info << "Alpha is: " << alpha << endl;



        #};

    }



}

However, I get the error:

Code:



    request for dictionary transportProperties from objectRegistry region0 failed

    available objects of type dictionary are

4(fvSchemes fvOptions fvSolution data)

It the transportProperties not created yet? Am I looking for it in a wrong manner?

A quick look at the laplacianFoam code suggests that the transportProperties dictionary is only created (inside an if statement) if DT doesn't exist (otherwise it's read). So to guess at a fix you could create a custom version of laplacianFoam in which you force the creation of the dictionary without the if statement, or create a dummy/copy of it inside your function object like :

Code:



    IOdictionary dummyTransportProperties //ensure the original isn't duplicated

    (

        IOobject

        (

            "transportProperties",

            runTime.constant(),

            mesh,

            IOobject::MUST_READ_IF_MODIFIED,

            IOobject::NO_WRITE

        )

    );



    //then read from dict

    const scalar alpha (transportProperties.getScalar("DT"));

Note that I've not tested the above code, but hopefully it will lead you in the right direction.

Caelan