Calculating Temperature Gradient
 

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

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.

Thnak you for the answer!

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

Best Regards

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;

}

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,