[arunimb]

Can anyone tell me how to modify a solver or write a utility to calculate Nusselt number at the wall? I have been following Johan Magnusson's report,however I am using OF 5 which is making it really difficult to follow the report.

Thank You
Arunim

[arunimb]

For anybody who wants to know

PHP Code:

        const fvPatchList& patches = mesh.boundary();

            forAll(wallGradT.boundaryField(), patchi)
            {
                const fvPatch& currPatch = patches[patchi];

                if (isA<wallFvPatch>(currPatch))
                {
                    wallGradT.boundaryFieldRef()[patchi] =
                        -T.boundaryFieldRef()[patchi].snGrad();
                    
                    nusseltNo = wallGradT*length/(Ts-Tinf);
                }
            } 


where, length, Ts and Tinf are user defined values.

[student666]

Can you explain how to add this calc to a solver like (e.g) buoyantSimpleFoam?

Thanks.

[arunimb]

Hello,
I have adapted it for pisoFoam. You can easily do it for buouyantSimpleFoam .
Here is the github link for my code
https://github.com/arunimb/CFD_openFoam
Cheers.

[student666]

Hi,

I've been able to modify the solver.
But I have a question.

My textbook refers to Nusselt number as for:
Nu = t' / y' = (ts - t)/ (y/L) * 1 / (ts-tinf)
that is the gradient of temperature at the wall.
with:

• ts = t wall
• t = temperature at calculation point
• tinf = freestream temperature
• y = space coordinate normal to wall
• L = characteristic Lenght

what is the meaning of this:

            dimensionedScalar
            (
                "wallGradT",
                T.dimensions()/dimLength,
                0
            )

is it that?

Previously you added also this line:

nusseltNo = wallGradT*length/(Ts-Tinf);

If wallGradT is
t' / y'

why multiply for length?

Thanks.

PS:added modified files to buoyantBoussinesqSimpleFoam

[Sedullo]

Hi student666,

I am new to OpenFOAM and I need to implement a code to caluclate Nusselt for buoyantBoussinesqPimpleFoam.

Could you tell me please what are the file I should modify and the codes I should write to get the average or local Nusselt number?

Sorry if I ask too much but I am not good with coding so I would need a sort of step by step explanation, thanks!

[charlliemarshalll]

Same problem here of how to use the php code in the openfoam