How to calculate the local Nusselt number for a tube using ANSYS Fluent

In this video, you can find out how to calculate the parameters of the Nusselt number including bulk temperature, and wall temperature for a tube in Ansys Fluent. Also, you will see how to generate the Iso-surfaces over the working fluid and over the tube wall.
Please see "A trick for creating many Iso-surfaces in ANSYS Fluent using the Fluent journal file" video in the following link:
• A trick for creating m...

[@cajamarcawarrior]

A great video. Useful, and well-explained. Thank you for sharing the knowledge.

[@akamcae]

We are happy to hear that, thank you.

[@user-oe6it3kb1c]

Thank you for your explanation,
When you calculate local wall temperature you used thin wall temperature,
But the local wall temperature in 3D is a line around the pipe, so it is not area weighted average, it is a length average

[@akamcae]

In ansys, we do not have a length average; so when you use area average, it is supposed to give you the average length of elements. To test my claim, please calculate the area of the line around the pipe, if it gives you the circumference of the tube, so, this method works.

[@user-oe6it3kb1c]

To calculate average Nu number must be calculate the area weighted average of the total wall and the outlet and the inlet mass weighted average for bulk temperature, is it correct

[@akamcae]

No, it's better to calculate the Nu number at each specific length of the tube and then calculate the average of all Nu number values using the methods to get the average value. The average method: www.cuemath.com/trapezoidal-rule-formula/

[@user-qo8md9mu5m]

How to calculate the average Nu? Thank you

[@akamcae]

You can calculate the average Nu number along the tube by using the trapezoidal rule. This is a simple method. OR; If you have access to Matlab software, you can use trapz( X , Y ) and then divide it by the length of the tube. See Eq. 14 in this paper doi.org/10.1007/s00231-018-2345-z.

[@JyotiSingh-ce3lc]

Please tell us how to calculate the local nusselt number, local heat transfer and thermal boundary layer at a specific Reynolds number

[@akamcae]

For calculating the local Nusselt number at a specific point, instead of taking Tw,avg, you need to calculate the Tw at the specific point. The same procedure for local heat transfer. For the local thermal boundary layer, make a line inside the domain that is normal to the wall, then report the temperature, I guess you can see the thermal boundary layer.