Talk:Boundary layer

Lack of pictures
An article like this would be greatly improved with some pictures, does anyone have any? I'll try and find some but I was thinking something along the lines of:

-Moody chart for a sphere, as the change in friction factor is well explained by boundary layers.

-Smoke blowing past a sphere or aerofoil in a wind tunnel.

-Transition to turbulence, flow over a flat plate perhaps.

-Velocity profiles (and temperature profiles) for flow over a hot plate.

-Flow through a duct showing the effect of adverse pressure gradients on boundary layer separation.

Anyone got any other suggestions? Andrew.Ainsworth 23:32, 22 May 2007 (UTC)

I just uploaded a simple boundary layer schematic that you might consider. Syguy 18:57, 19 September 2007 (UTC)
 * Why is the turbulent profile so much higher than the laminar profile? I was always taught that both profiles had the same area of effect, but that the curve of the turbulent profile was a little different- the curve was "fuller".  This does not seem to be reflected in the drawing.  I'm not sure I like how they are set up one beside each other either.  The two profiles should be separated more to avoid confusion.--Dj245 00:02, 23 October 2007 (UTC)
 * I authored the picture so it might help if I try to explain it a little. I wanted to contrast the difference between the free stream, laminar and turbulent velocity profiles on the same picture - given that the notion of a boundary layer is tightly couple to velocity profiles. Next, I wanted to show there is a transition region between the turbulent and laminar regions, so I used a fade between the two colors representing the fully developed laminar (dark blue) and fully developed turbulent (red) regions. Finally I wanted to show that a turbulent boundary layer is thicker than the equivalent laminar boundary layer at the same location, hence the hump at the transition point. Of course the vertical scale in the picture is greatly exaggerated to highlight the height difference. However, turbulent boundary layers are thicker, causing higher drag, than an equivalent laminar boundary layer - assuming it could remain laminar. Syguy 16:36, 23 October 2007 (UTC)
 * OK, I can see what you were getting at now. But only with this long explaination does it make sense to me.  --Dj245 21:39, 23 October 2007 (UTC)
 * I added an explanation to the image, along the lines of explanation I gave above. Hopefully that may help. Syguy 18:53, 24 October 2007 (UTC)


 * The speed profile of the turbulent flow does not represent the diffence between laminar and turbulent flow. It seems like it was just an upscaled-in-height laminar degree 2 v-profile, but its not. In turbulent flow, the velocity stays high much closer to the wall, with much higher gradient close to the wall, wich is the main reason for the higher drag. I´m sure you know. The exact thing is all but trivial, but there should be the possibility to notice the difference at first sight. Could this be changed? —Preceding unsigned comment added by 93.129.31.199 (talk) 16:24, 28 August 2010 (UTC)

Naval architecture
I moved most of this section to added mass, since it seems to confuse added mass with boundary layer effects. For instance for a ship of 100 m length and 10 m draft, at 20 m/s, the boundary layer will be of the order of 0.1 m thickness, so a boundary-layer mass of 2x100x10x0.1=200 kg. Which will be only a tiny fraction of the ship mass. The remarks about mass affected by aircraft are off-topic: not about naval architecture and not about boundary layers, so I removed them. -- Crowsnest (talk)

Heat and mass tranfer
Boundary layer is a concept used in all transport phenomena (mass transfer, heat transfer, momentum transfer, etc.), but the page talk almost exclusively of the momentum transfer. Please generalize it, in particular it is important to generalize the incipit. --Daniele Pugliesi (talk) 12:15, 28 October 2014 (UTC)

Convective transfer constants from boundary layer analysis
The integrated equations are wrong as they still depend on the integrated variable x — Preceding unsigned comment added by 152.96.212.60 (talk) 10:07, 11 March 2020 (UTC)

Merge?
Boundary_layer_thickness does not seem very useful, especially since all the calculation are on this page.Tigraan (talk) 15:50, 29 January 2015 (UTC)
 * Oppose:this is a rather complex subject, and having a page that focuses just on the boundary layer thickness (rather than other issues covered on the main page) is, in my view, helpful. Klbrain (talk) 09:51, 30 July 2017 (UTC)

General sense of the title
In case the issue is about the general sense of the term, I've never heard of any other meaning of the word, neither www.oxforddictionaries.com nor www.merriam-webster.com have, apart from the already linked in anatomical feature. — Preceding unsigned comment added by 84.236.116.111 (talk) 06:13, 9 March 2015 (UTC)

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