Nonsensical results with wall heat flux boundary condition
1 Attachment(s)
I am befuddled with heat transfer in OpenFOAM and would very much appreciate someone's insight.
My test case is a 2D parallel channel that's 50-mm tall and 1000-mm long. The Reynolds number is 40,000 and the fluid is air. I'm using OF6 and the rhoSimpleFoam solver with RANS turbulence modeled with kOmegaSST. I first ran my solution with a uniform temperature of 293K. Everything checks out fine. My mesh is resolved to provide y+ ~ 0.3 at the walls. The fluid velocity profile develops nicely. Next, I changed my top and bottom wall to have a fixed temperature of 353K. Again, everything checks out fine. I can post-process the wall heat flux and see about 1000 W/m^2 being delivered to the walls. In paraView, the temperature profile looks normal, and I can see the thermal boundary layer develop. Finally, I changed my top and bottom wall to externalWallHeatFluxTemperature. I've tried to set a flux of 1000 W/m^2. The solution still progresses to convergence, however, the results now show cryogenic temperatures at the wall and negative heat flux. Changing the heat flux to -1000 W/m^2 doesn't appear to change the results either. Here's how I'm trying to set the BC: Code:
upperWall Many thanks, ~ Joseph |
Solution found - setting a fixed heat flux boundary condition
All,
Well, after some more digging, I believe I found the answer. For archival, here's the helpful post: Defining Heat Flux to wall The solution is to use the fixedGradient boundary type and set the value to q"/K where q" is the desired heat flux and K is the thermal conductivity of the fluid. Code:
lowerWall |
You may want to re-run with some of the debug switches turned-on. I see that the bc will print additional info.
This may provide more insight into what is going on at bc. However, I am not 100% on which debug flag to turn on. You could add the following to your controlDict file (setting the values to 1 turns the debug flags on) ... Code:
DebugSwitches { |
All times are GMT -4. The time now is 05:27. |