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-   -   Huge Heat Transfer Coefficient with SST turbulence model (http://www.cfd-online.com/Forums/cfx/68294-huge-heat-transfer-coefficient-sst-turbulence-model.html)

andoss September 14, 2009 04:13

Huge Heat Transfer Coefficient with SST turbulence model
 
Hello!

I am modelling conjugate heat transfer at a pipe - the pipe is cooled by air, which flows through the pipe. Therefor I use the SST turbulence model. The y+ value is y+ <1 (around 0.5) The number of nodes in the boundary layer is about 15. The value for the wall heat transfer coefficient which i got from the simulation is very high with 26105,7 W/mēK (From analytical calculations I got a value around 650 W/mēK)

Does someone know what the reason could be?

Thank you in advance,
Andy

denizen September 14, 2009 05:10

try to check reference temperature for calculation of HTC

andoss September 15, 2009 09:23

The temperatures are ok. I did the simulation also with the k epsilon turbulence model (with scaleable wall functions) and then I got much better results than with the sst model. So I dont understand why the results with use of the sst turbulence modell are so high.

ghorrocks September 15, 2009 18:29

I don't think you have understood denizen's point. HTC is by default referenced to a local temperature which is another variable available for viewing in CFD-Post called "Wall Adjacent Temperature". This variable is often miles away from the reference temperature an engineer would use in the bulk flow.

andoss January 9, 2010 08:40

Thank you! This was very helpful!


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