modeling interface in conjugate heat transfer
 

Hello I am modeling conjugate heat transfer in a channel with thick walls. The fluid is air and solid zone is silicon. The fluid is entering at the 1m/s and 350K. There is no heat flux applied anywhere and all the wall are adiabatic. The solution is initialized with 300K and I expect to get the isothermal temperature distribution in the system but temperature is increasing to 5000K. I think the problem is at the interface between solid and fluid zone. I have coupled the walls at the interface. Can anybody tell what should be the right boundary conditions at the interface?

Vivek

Re: modeling interface in conjugate heat transfer
 

U dont need to define any boundary condition at solid-fluid interface....its just the interface should be coupled and would appear as face and face shadow....well..about temperature...5000K may means ur case didnt converge??? i guess temperature of the fluid at the inlet of teh system is lot less than 5000K

Re: modeling interface in conjugate heat transfer
 

I haven't defined any BC at the interface...energy residual is less than 10^-8 but the temperature keeps increasing till it reaches 5000K. The inlet temperature is 350K....If I change the working fluid from air to water the solution converges....Also if I remove the solid zone and just solve for the fluid zone I get the correct result...but when I am including both solid and fluid it is acting weirdly...I think fluent is not handling the interface properly...Has anybody experienced this problem....

Re: modeling interface in conjugate heat transfer
 

Connect the faces of the solid and the fluid region in GAMBIT itself. The face will automatically assume the BC of coupled wall with a shadow being created. Then try solving the problem in FLUENT.

Regards, Rameche Candane. S

Re: modeling interface in conjugate heat transfer
 

I am using coupled boundary condition...but still I am not getting the correct result...is coupled boundary condition the right BC???

Re: modeling interface in conjugate heat transfer
 

Coupled wall is a BC that is automatically taken when a solid region and fluid region have a common interface. Its a 2 sided wall. I am sure that either you may not have connected the faces of the solid and fluid region properly or u might be having an extra face there. Check the gambit file r reconstruct the mesh file.

Regards, Rameche Candane