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local distribution of Nusselt Number in Ansys CFX

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Old   November 21, 2017, 23:24
Default local distribution of Nusselt Number in Ansys CFX
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CongTao
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Hi,
i'm doing a simulation of annular finned tubes on my CFX.Now,i want to make a contour plot of the local Nusselt number .However,I've been using the software for a month.i don't know how to make it.
Can someone please direct me on how to make the contour plot just like this one.
Help please.

Thanks.
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Old   November 22, 2017, 15:04
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What are you asking? How to make a contour plot? How to calculate nusselt number?

For Nusselt and HTC, see the FAQs.
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Old   November 22, 2017, 21:39
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Quote:
Originally Posted by evcelica View Post
What are you asking? How to make a contour plot? How to calculate nusselt number?

For Nusselt and HTC, see the FAQs.
Thank you for your reply.The problem i want to ask is how to make a contour plot of the Nusselt number.i have tried to use other's method,like this picture,but it didn't work well.
English is not my first language,so i didn't express my problem accurately.i'm sorry for this.[ATTACH][/ATTACH]
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Old   November 23, 2017, 02:21
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+First you make a plane where you want to show your contour.

+Than you make a contour with a location (plane) and colors nuselt number.

+than you disable the plane in the tree because it is grey by default and you dont need it. if you dont disable it you will have two planes on the same place which will interfere with eachother.
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Old   November 23, 2017, 03:36
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Thanks for your suggestion.Maybe i didn't express my problem accurately.I know how to make a contour plot of Variables.However,i don't konw How to write the expressions of Nu on my CFX.I try to define the Nusselt number,but it didn't work well.Do you have any examples of doing it?
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Old   November 27, 2017, 10:11
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I told you once already to see the FAQs for Nusselt number and HTC info.
https://www.cfd-online.com/Wiki/Ansy...ficient_in_CFX
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Old   November 27, 2017, 10:48
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Thank you for your suggertion.i have done it following the FAQs.Maybe the bulk temperature I have setted is wrong,so the result is not very well.The bulk temperature that i calculated by the mass average temperature .Is it right?
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Old   November 27, 2017, 22:45
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You will need to look at what the results you are comparing against has done to determine whether mass average temperature is appropriate.

Don't forget that your simulation may "simply" be inaccurate, again this is an FAQ: https://www.cfd-online.com/Wiki/Ansy..._inaccurate.3F
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Old   November 28, 2017, 02:01
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MyHTC = (Wall Heat Flux / (((Wall Heat Flux / Wall Heat Transfer Coefficient) + Wall Adjacent Temperature) -298.15[K]))

This shoul work for htc. 298.15K is the ambient temp in this case.
Althoug I usualy prefer to go by the other method and set T-bulk in expert parameters.

I dont understand this part..
"The bulk temperature that i calculated by the mass average temperature .Is it right?"
It can be what ever you like, you have to decide what are you going to use this HTC for in the future
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Old   November 28, 2017, 08:39
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Thanks a lot.i want to get the local Nusselt number along the fin.Maybe i need to get the expression of the mass average temperature along the air flow direction.
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