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total sensible heat transfer rate to determine convergence

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Old   May 23, 2020, 03:02
Default total sensible heat transfer rate to determine convergence
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Weiqiang Liu
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Hi all,

I am doing a propane combustion simulation with fluent. Actually I am trying to reproduce literature results. My maximum temperature is 100K lower than literature results.

I am wondering is this because my case is not converged yet. all the residuals in my case are flat. The monitor variable kept constant as well. Then I checked mass balance of the combustor, it's balanced. Finally I checked the total sensible heat transfer rate. The detailed data set is as follows:

inlet: -58.4W

outlet:-200W

external_wall:-182W

heat of reaction source:461.55 W

net:9.74 W

I know that the net heat transfer rate of the whole system should be 0 if the case is fully converged. However, I can not make it smaller with further iteration.

I am wondering is this an acceptable value to determine convergence or are there any ways to decrease this value further in order to get converged case.

Best regards

Weiqiang
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Old   May 23, 2020, 03:45
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i would suggest a smaller one
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Old   May 23, 2020, 05:33
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Quote:
Originally Posted by qin chunqiu View Post
i would suggest a smaller one
so it should be very close to zero in order to be converged, right?
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Old   May 23, 2020, 07:54
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Quote:
Originally Posted by Weiqiang Liu View Post
so it should be very close to zero in order to be converged, right?
Yes. At least 5% of the smallest heat flux among thouse boundaries.
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Old   May 23, 2020, 10:31
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Quote:
Originally Posted by qin chunqiu View Post
Yes. At least 5% of the smallest heat flux among thouse boundaries.
Thanks very much! I'll try to further decrease the net heat transfer rate.

By the way, do you have some tragedies to aid convergece in the simulation of combustion.

I defined both my surface and volume reaction rate with UDF.

Best regards

Weiqiang
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Old   May 26, 2020, 04:46
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Dear Weiqiang,
I am sorry that I know nothing about combustion.

Best,
ChunQiu
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Old   May 26, 2020, 08:16
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Originally Posted by qin chunqiu View Post
Dear Weiqiang,
I am sorry that I know nothing about combustion.

Best,
ChunQiu
thank you!

weiqiang
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