is it true that FLUENT calculates Nusselt wrong?

December 22, 2005, 02:26

dear friends,

My question is ; I've started working on natural convection between horizontal plates and i calculate the surface nusselt number over my one of the plate and compare them with the experimental ones and the results seem ok. i'm sure that i gave the correct boundary conditions and operating conditions and the discritization scheme vs...

but later on i've heard from some academicians that FLUENT cannot give the correct Nusselt number values for forced convection although the correct inputs are given. they are saying that we are writing the heat flux on the plate on a data file by FLUENT and then calculate the nusselt number by hand.!!! is it really like that for forced covection. I really suprised when i heard that. because i didn't see any discussions about this topic in any forum or such.

if this is correct that FLUENT gives wrong Surface nusselt number for forced convection , is it also like that in natural convection because i'm working on natural convection.

moh1367 · February 14, 2010, 03:51

Hi guys!

My case is very simple , its laminar flow in a pipe with constant wall temperature. I take the length as long as the flow can reach to fully thermally and Hydrodunamically developed. When I get the Nusselt Number from the xyplot/Surface Nusselt Number it can seemed that the Nu begins from a large number(as predicted by theory) and go toward zero at the end of pipe (the theoric value is 3.66). Can anybody help me?
I can send my case to you for more information.

Thanks alot
.

December 22, 2005, 02:26	is it true that FLUENT calculates Nusselt wrong?	#1
muhittin Guest Posts: n/a	dear friends, My question is ; I've started working on natural convection between horizontal plates and i calculate the surface nusselt number over my one of the plate and compare them with the experimental ones and the results seem ok. i'm sure that i gave the correct boundary conditions and operating conditions and the discritization scheme vs... but later on i've heard from some academicians that FLUENT cannot give the correct Nusselt number values for forced convection although the correct inputs are given. they are saying that we are writing the heat flux on the plate on a data file by FLUENT and then calculate the nusselt number by hand.!!! is it really like that for forced covection. I really suprised when i heard that. because i didn't see any discussions about this topic in any forum or such. if this is correct that FLUENT gives wrong Surface nusselt number for forced convection , is it also like that in natural convection because i'm working on natural convection.

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February 14, 2010, 03:51		#2
moh1367 Member Mohammad Zakerzadeh Join Date: Dec 2009 Location: Aachen, Germany Posts: 40 Rep Power: 16	Hi guys! My case is very simple , its laminar flow in a pipe with constant wall temperature. I take the length as long as the flow can reach to fully thermally and Hydrodunamically developed. When I get the Nusselt Number from the xyplot/Surface Nusselt Number it can seemed that the Nu begins from a large number(as predicted by theory) and go toward zero at the end of pipe (the theoric value is 3.66). Can anybody help me? I can send my case to you for more information. Thanks alot .