[Chris_321]

Hello everybody,

i'm wondering how a cfd software calculate conjugate heat transfer.

Lets assume the following

http://www.pic-upload.de/view-26247212/temp.png.html

T_Boundary is on the far left set to 300 K

If i know the contact temperature then the temperature everywhere in the solid can calculate with the fourier heat equation law and the temperature in the fluid can be calculated with the heat equation.


But how will cfd calculate the contact temperature? Is it calculate by the energy equation with substitution of the contact temperature by the fourier law between the boundary and the contact area?

How is this done with many elements?

Regards
Chris

[mprinkey]

Conjugate heat transfer in CFD is normal done by meshing the solid and fluid zones. The temperature at the contact surface will not (necessarily) be ONE temperature. It will be a line (2D) or a surface (3D) of temperature corresponding to the solution of the heat transfer equation (2/3D Fourier law in the solid cells and Advection/Diffusion equation in the fluid cells).

If the solid is poorly conductive, you can reduce the solids to a simple BC for the fluid zone. But it is not possible to do that in general--usually because the solid regions often conduct heat very well and directly impact the temperature profile in the fluid zone.

[Chris_321]

Thank you for your reply!

But im still wondering how at a discrete point the contact temperature is calculated.

How are the fourier law and the advection equations coupled?


Or is it just this way?
http://www.pic-upload.de/view-26250491/temp.png.html


And then the heatflow from the wall to the fluid is added in the energy equation of the navier stokes equations?



If the temperature at the wall is calculated with the fourier law and the temperature of the fluid is calculated with the energy equation how the two temperatures (wall and fluid) are blanced in the next iteration step? Is just a heat source/sink applied to fourier and the energy equation?