[pupo]

Good Night all!

I'm with a very minor, very noobish problem i can't solve/find a solution online:

how do i convert a a heat transfer coeficient at a wall ( q = 200 w/m² ) to an OpenFoam Fixed gradient boundary condition? ( gradient uniform ?????; )

I used to have this in a manual, that I foolishly borrowed a collegue, that explained this very clearly and now I'm stuck in this silly detail.

Thank you very much!

Best Regards,
Pupo

[rapierrz]

Hi pedro,

For conjugate heat transfer if you want to apply heat flux to solid boundary you

can use gradT=q/Ksolid.

If you want to apply to boundary near fluid you can use gradT=q/Kfluid.

[pupo]

Thnak you for the answer!

However, K changes with temperature on the fluid side... how do i account for that?

Best Regards

[rapierrz]

For this condition you can use of groovyBc for example:


Wall
{
type groovyBC;
valueExpression "0";
variables "K1=0.6;K2=0.02;Keff=alpha1*K1+(1-alpha1)*K2";//alpha is volume fraction
gradientExpression "2000/Keff";
fractionExpression "0";
value uniform 293;

}

[pupo]

Thank you, i had completely forgot about good old groovy :P

meanwhile i found this: http://openfoam.com/documentation/cp...ml/a00744.html

it seems to do what i want and to take into consideration the varying conductivity of the fluid.

Best Regards,