Talk:Nusselt number

message: This equality is far too general to be of any help. For instance, in natural convection in cavities is literal, in laminar internal flows can be descriptive of the situation and in turbulent and external flows is simply false. To explain fully what it means would require several pages. In addition, it tends to confuse students. For instance, they then mix-up Nusselt and Biot numbers, since the ratio is much more meaningful for the latter.
Xtobal (talk) 12:02, 14 April 2008 (UTC)
replies: text: Fair enough. I have no problem with you removing that part of the equation now that you have explained that, but before it appeared more like vandalism because there was no explanation to why it was deleted. In the future I recommend that you used the edit summary. Thanks! --Wizard191 (talk) 12:55, 14 April 2008 (UTC)
thread_title:  Ratio of convection to conduction transfer 

message: I guess you can say that (for natural convection) Nu is function of Ra & Pr but Ra = Pr*Gr. So isn't it more logical to just say Nu = f(Ra) or Nu = f(Gr,Pr). (and Nu = f(Re,Pr) for forced convection)  —Preceding unsigned comment added by 134.184.120.160 (talk) 12:41, 17 August 2008 (UTC)
thread_title:  Nu = f(Ra, Pr) 

message: Why are there citations for 3 editions of the same book...164.54.53.85 (talk) 19:40, 19 March 2010 (UTC)
replies: text: Because people added content from three different editions so it must be noted. I know I have one of those editions, but I couldn't say I had it from one of the other editions referenced, therefore the three are noted. Wizard191 (talk) 20:59, 19 March 2010 (UTC)
thread_title:  references 

message: 'In this context, convection includes both advection and conduction.' How can convection include conduction?! | Moemin05 (talk) 16:49, 29 March 2012 (UTC)
replies: text:  It is a huge mess: some books consider that convection refers only to natural or free convection, others which define convection as advection+conduction and some as synonym of advection. The definition changes in the past several times and all modern books are not using the same definition Biglama (talk) 12:45, 30 March 2012 (UTC)
thread_title:  Confusing introduction 

message: The context section says "An understanding of convection boundary layers is necessary to understanding convective heat transfer between a surface and a fluid flowing past it." The diagram also makes it look like the fluid is flowing past the surface and even has a variable "V" written on it, which I suppose is probably velocity. However, it's not clear to me from any of the rest of the description that the motion of the fluid parallel to the surface is considered or matters. Also, the reason I came to this page was because I was reading a paper that involved modelling convection in exoplanet mantles as part of modelling their thermal evolution (https://doi.org/10.1051/0004-6361/201935714), which contained
The heat fluxes at the top and bottom of the mantle (qman-top and qman-bot) are expressed in terms of the temperature drops across the top and bottom thermal boundary layers (ΔTtop and ΔTbot), and the Nusselt number Nu for the entire mantle, i.e.,
:q_\mathrm{man-j}(t) = \mathrm{Nu}(t)\frac{k\Delta T_\mathrm{j}(t)}{h}, j=top,bot
where k is the thermal conductivity of the mantle (either constant or temperature-dependent; Table 1) and h is the height of
the mantle.
This seems to me to be a case where a Nusselt number is being used  in a situation where the fluid is not flowing parallel to the surface.DubleH (talk) 03:30, 12 December 2020 (UTC)
thread_title:  Does the fluid have to be flowing past the surface?