[victor198936]

Hi Everyone,

I'm a new OpenFoamer and I've been stopped by this problem here over the past four days so I'm keen in borrowing professional minds here.

Basically, I'm trying to access members value of strainRate() such that I can compare the value to a real number. I understand the type of strainRate() is volScalarField and there should be two readFields, internalField and boundaryField, that should be able to access. My code is below:

forAll(strainRate().internalField(),cellI)
{
if (strainRate().internalField()[cellI] < 0.17)
{
return
M;
}
else
{
return
k_*((-0.00795*log(strainRate()/m_) + 0.344)/(sqr(log(strainRate()/m_)) + 9.02*log(strainRate()/m_) + 25.0) + (-0.0128*log(strainRate()/m_) + 0.398)/(sqr(log(strainRate()/m_)) + 6.11*log(strainRate()/m_) + 14.5))/rho_;
}
}

However, when I compile the code, it said they could not find out internalField.

ShearThinning.C: In member function ‘Foam::tmp<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> > Foam::viscosityModels::ShearThinning::calcNu() const’:
ShearThinning.C:53:1: error: ‘class Foam::tmp<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> >’ has no member named ‘internalField’
ShearThinning.C:55:18: error: ‘class Foam::tmp<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> >’ has no member named ‘internalField’

Can anyone suggest the reason and provide solution to work it out?

Appreciate in advance!

[Tobi]

Dear Shuang,

based on the fact that I cannot find the ShearThinning.C file, I suppose that it is something you developed. Based on your output you are not accessing to a volScalarField you try to access to a tmp<volScalarField>. At the moment and out of the box I cannot tell which is the right way but it could be that it is:

shearRate()().internalField()[cellI]

Otherwise build a new volScalarField like:

const volScalarField& tmp = shearRate();

And use that one.

[victor198936]

Thank you for the response Tobi.

Quite honest, I'm not quite sure the difference between volScalarField and tmp<Foam::volScalarField>. Can you elaborate more?

Also, what're the good resources/tutorials for understanding the OpenFoam programming code, structure. It's very difficult to program without understand the basic. Could you kindly suggest?

Thanks

[Tobi]

OpenFOAM is just C++. So if you want to know how things work, you should know C++. That's it. The tmp<T> is a class but not a normal class it is a template class. You can use doxygen to check out the stuff. Typing in tmp will lead you to the abstract template class tmp<T> (T stands for the abstract type, like volScalarField, scalar, volVectorField, tensors etc.). However, the tmp class does not provide any internalField() function. That's why you get the error. To get rid of the error you either extract the volScalarField and apply the internalField() function, or you can use the ref() function. However, the ref() function returns a non-const reference to the internal field. It should be also possible to take the pointer to the object with ptr() and access via pointer to to your volScalarField. E.g.

//- I dont know what shearRate is in your case, but I address it be an object for now
const volScalarField* ptrToObject = shearRate.ptr()  

forAll(ptrToObject->internalField(), cellI)
{

}

Based on the fact that (already mentioned) I don't know what you are doing, and what shearRate() stands for, I cannot give you a more accurate answer. One hint, it also can be that you just need to use what I said before:

//- Again shearRate is the object
const volScalarField* ptrToObject = shearRate();

If you do not understand what I was writing. Checkout C++ books because I will not explain how c++ works.
Good luck.