NU calculation
 

Hi every body,
I really tried my best to solve my problem ,but unfortunatly I could'nt:(. the case:
its laminar flow in a pipe with constant wall temperature.. 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).in fact what should I do to reach the Nu=3.66 in constant wall temperature thourgh the length of tube?
Thanks alot

YOur air temperature may be aproaching your wall pipe temperature. Try increasing the flow.

but I already tried that. you know let me ask you my question more clear. I want to compute mass weighted average fluid temperatures at step intervals of 10 mm in the axial direction along the tube.
Meanwhile I have attached the data file for more details.
thank you again/

heidar
 

at imlet u must obtaine infinite number. it is a rule
but please atach ur graph and one pic of ur sample.
;)