Different temperature on boundary fluid-solid in CFX

Twix · June 24, 2009, 09:30

Hi,
I have problem and need help. I do CHT simulation of flow around turbine vane and use SST
model with and without turbulence transition and K-Omega model. I create line on boundary
fluid-solid and check temperature. The temperature on
solid side is different from this on fluid side. The difference is about 5%. My question is
why, because those value suppose to be equal. I add chats.
Thanks in advance

ghorrocks · June 24, 2009, 18:49

Hi,

For CHT simulations you should add imbalances as a convergence critereon in addition to the normal residuals. What imbalances have you converged to?

Glenn Horrocks

Twix · June 25, 2009, 16:11

Hi,
thanks for so fast reply. my settings for convergence criteria are: Residual type- MAX, Residual target- 0,00001. In expert parameters I didn’t mark imbalance normalization type.

Regards

ghorrocks · June 25, 2009, 18:50

Hi,

As I said, a CHT simulation can have high imbalances (which leads to temperature imbalances) but well converged residuals. That is why you should also use imbalances as a convergence critereon for CHT simulations. It is on the solver tab in CFX-Pre (not an expert parameter).

Glenn Horrocks

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June 24, 2009, 18:49		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	Hi, For CHT simulations you should add imbalances as a convergence critereon in addition to the normal residuals. What imbalances have you converged to? Glenn Horrocks

June 25, 2009, 16:11		#3
Twix Member Michal Join Date: Mar 2009 Posts: 38 Rep Power: 19	Hi, thanks for so fast reply. my settings for convergence criteria are: Residual type- MAX, Residual target- 0,00001. In expert parameters I didn’t mark imbalance normalization type. Regards

June 25, 2009, 18:50		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	Hi, As I said, a CHT simulation can have high imbalances (which leads to temperature imbalances) but well converged residuals. That is why you should also use imbalances as a convergence critereon for CHT simulations. It is on the solver tab in CFX-Pre (not an expert parameter). Glenn Horrocks