there is a problem with fully developed Nusselt number

eeman · April 25, 2011, 15:29

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

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

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

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???

April 25, 2011, 15:29	there is a problem with fully developed Nusselt number	#1
eeman New Member iman mohammadi Join Date: Jul 2010 Posts: 11 Rep Power: 15	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. Last edited by eeman; April 26, 2011 at 18:44.

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April 17, 2012, 04:14		#2
raghu.tejaswi New Member Learner Join Date: Nov 2011 Location: Ingolstadt Posts: 27 Rep Power: 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.