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How to evaluate Nu-average

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Old   March 26, 2016, 16:04
Default How to evaluate Nu-average
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Hello I am wondering how I can estimate average Nusselt number from Fluent for flow through a duct like the equation appear at the image attached?

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Old   March 28, 2016, 10:07
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Any reply is appreciated?

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Originally Posted by mariam.sara View Post
Hello I am wondering how I can estimate average Nusselt number from Fluent for flow through a duct like the equation appear at the image attached?

Thanks
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Old   March 28, 2016, 10:44
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You can go under reports, do a surface integral of Nusselt number.

You can't do exactly what you have written (by integrating the average Nu at a given section) because that is for 1D flow, and Fluent is 3D. There is no convenient average Nusselt number at a cross-section because a cross-section is not conveniently generalizable to 3D.
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Old   March 28, 2016, 10:49
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Thank you for the reply. I do not mean exactly what I mention at the relation actually I am running 3D channel and want to know how I can predict Nusselt average on it? You mean I need to find integral for Nusselt over the overall domain? is that will represent Nu average?


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Originally Posted by LuckyTran View Post
You can go under reports, do a surface integral of Nusselt number.

You can't do exactly what you have written (by integrating the average Nu at a given section) because that is for 1D flow, and Fluent is 3D. There is no convenient average Nusselt number at a cross-section because a cross-section is not conveniently generalizable to 3D.
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Old   March 28, 2016, 23:10
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Quote:
Originally Posted by mariam.sara View Post
Thank you for the reply. I do not mean exactly what I mention at the relation actually I am running 3D channel and want to know how I can predict Nusselt average on it? You mean I need to find integral for Nusselt over the overall domain? is that will represent Nu average?
A type of weighted-integral, yes. Isn't that what an average is?

For example, an area-weighted average integral as you have written.
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