CFD Online Discussion Forums - How to set the thermal conductivity?

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How to set the thermal conductivity?

I need to know what is the thermal conductivity value of my simulation. I am simulating a natural convection problem using buoyantPimpleFoam, but I do not know where to read k (thermal conductivity).

Is it somewhere in the thermophysical properties?

Code:

/*--------------------------------*- C++ -*----------------------------------*\

  =========                 |

  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox

   \\    /   O peration     | Website:  https://openfoam.org

    \\  /    A nd           | Version:  6

     \\/     M anipulation  |

\*---------------------------------------------------------------------------*/

FoamFile

{

    version     2.0;

    format      ascii;

    class       dictionary;

    location    "constant";

    object      thermophysicalProperties;

}

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //



thermoType

{

    type            heRhoThermo;

    mixture         pureMixture;

    transport       const;

    thermo          hConst;

    equationOfState perfectGas;

    specie          specie;

    energy          sensibleEnthalpy;

}



pRef            101325;



mixture

{

    specie

    {

        nMoles          1;

        molWeight       28.9;

    }

    thermodynamics

    {

        Cp              1006.591;

        Hf              0;

    }

    transport

    {

        mu              1.85e-5;

        Pr              0.7;

    }

}





// ******************************

Hi,

You might want to check the definition of the Prandtl number (Pr):
https://en.wikipedia.org/wiki/Prandtl_number

The thermal conductivity k is uniquely identified because the values of mu, Cp and Pr are specified.

Hope this helps,
Fumiya

Quote:

Originally Posted by fumiya (Post 778530)

Hi Fumiya,

That was so helpful! I understood that the value of k that I was using was wrong because I changed mu in my simulation.

Then I have another question, what about the Thermal Expansion (Beta)? what are the parameter which affect the value?

I ask that because I need it to calculate the Grashof number

Hi Sedullo,

For a perfect gas, the thermal expansion is a inverse of the absolute temperature:
https://en.m.wikipedia.org/wiki/Thermal_expansion

Hope this helps,
Fumiya

Quote:

Originally Posted by fumiya (Post 778530)

Hi Fumiya,

If the vicous is sutherland law, does it has relation between k, As, Ts?