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-   -   there is a problem with fully developed Nusselt number (http://www.cfd-online.com/Forums/fluent-udf/87646-there-problem-fully-developed-nusselt-number.html)

eeman April 25, 2011 15:29

there is a problem with fully developed Nusselt number
 
Dear all

as you know, Nusselt number for a fully developed laminar flow
in parallel palates should be 7.54 and for example, for kn=0.1 should be 4.75. I have the correct answer for Nusselt number when there is no slip region, but for slip-flow my Nusselt numbers are wrong.
I've checked also slip- flow and heat transfer in rectangular microchannels but as same as parallel plates for the slip region fully developed Nusselt number are wrong but temperature profile is correct.
It seems to be all correct except Nusselt number.


i would appreciate for any help.

raghu.tejaswi April 17, 2012 04:14

I am not sure eeman, but the Nusselt number in FLUENT is always wrong for me. It is always very high. I am really not sure how this is evaluated. Also the HTC at the surface. I dont understand what is the T_ref FLUENT considers to calculate HTC and what is the Nusselt number.

Patrick1 April 19, 2012 02:48

Quote:

Originally Posted by eeman (Post 305009)
Dear all

as you know, Nusselt number for a fully developed laminar flow
in parallel palates should be 7.54 and for example, for kn=0.1 should be 4.75. I have the correct answer for Nusselt number when there is no slip region, but for slip-flow my Nusselt numbers are wrong.
I've checked also slip- flow and heat transfer in rectangular microchannels but as same as parallel plates for the slip region fully developed Nusselt number are wrong but temperature profile is correct.
It seems to be all correct except Nusselt number.


i would appreciate for any help.

Did you try and calculate the Nusselt number yourself from the flow data?

shahvar September 24, 2012 00:36

Quote:

Originally Posted by Patrick1 (Post 355529)
Did you try and calculate the Nusselt number yourself from the flow data?

how can calculate nusselt number by fluent data?

raghu.tejaswi September 24, 2012 01:36

Quote:

Originally Posted by Patrick1 (Post 355529)
Did you try and calculate the Nusselt number yourself from the flow data?

Patrick, when you say flow data, do you mean analytically with formulae???


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