Talk:Dynamic pressure

message: I can't figure out any units in which R=1716. I get 25.54 mbar/(°R·lb/ft3), for what it's worth. —Ben FrantzDale 16:00, 31 January 2007 (UTC)
replies: text: It's 1716 ft·lbf/(slug·°R). I'll add it in. 164.107.197.169 06:47, 9 February 2007 (UTC)
thread_title:  R = 1716 what? 

message: Putting the dynamic pressure equation in terms of the Mach number, \gamma and static pressure under a Compressible flow heading is misleading. Acknowledging that the equation for dynamic pressure has limited usefulness at higher subsonic Mach numbers, it might be more appropriate to retitle this section as something like 'alternative forms of the [dynamic pressure] equation' and addressing any confusion between dynamic and impact pressures separately. (Weirpwoer (talk) 15:37, 26 November 2009 (UTC)
replies: text: I agree.  As I promised here, I will think about this over the next couple of days, and suggest a suitable way to rectify the errors I introduced by assuming \tfrac12 p_s \gamma M^2 is significant for all Mach numbers. Dolphin51 (talk) 21:55, 26 November 2009 (UTC)
thread_title: Compressible flow

message: Impact pressure says "Expressing the incompressible dynamic pressure as \;\tfrac{1}{2}\gamma PM^2" (emphasis added).  
The present article has the identical equation — albeit with the preferable lowercase p nomenclature for pressure — as a result under the heading "Compressible flow".  
Is that consistent? (Because it doesn't seem so.)
—DIV (137.111.13.4 (talk) 07:46, 11 November 2020 (UTC)
thread_title:  When it's compressible 

message: 1) The quote "the dynamic pressure is equal to half rho vee squared only in incompressible flow." attributed to Houghton and Carpenter is not to be found in the Butterworth-Heinemann 2017 edition, and neither is there a Section 2.3.1. Gpsanimator (talk) 00:11, 9 May 2023 (UTC)
replies: text: The cited source is the 1997 1993 edition of Houghton and Carpenter. It isn't surprising that the 2017 edition is different. What would be surprising is if the sentiment of this quotation is not to be found in Houghton and Carpenter the 2017 edition - the background is that some authors (chiefly British authors) define dynamic pressure to be the difference between total (or stagnation) pressure and static pressure; in incompressible flow that is half rho vee squared. In contrast, some authors (chiefly North American) define dynamic pressure to be half rho vee squared for all flows, and therefore having relevance only in incompressible flows; these authors define the difference between total pressure and static pressure (in compressible flows) to be impact pressure or ram pressure. I suggest you look through the 2017 edition and see which of these two definitions is used. Feel free to create a new in-line citation based on the 2017 edition. Dolphin (t) 13:25, 9 May 2023 (UTC)
thread_title:  Inaccurate references 

message: In the Physical Meaning section, it is said that "At a stagnation point the dynamic pressure is equal to the difference between the stagnation pressure and the static pressure, so the dynamic pressure in a flow field can be measured at a stagnation point."
This is not true. This should be changed to: "For incompressible flow, the dynamic pressure is equal to the difference between the stagnation pressure and the static pressure, thus dynamic pressure can be used to measure the flow velocity. Because the flow has no velocity at a stagnation point, the dynamic pressure at a stagnation point is 0, and the static pressure is equal to the stagnation pressure."
See this website for reference: https://www.princeton.edu/~asmits/Bicycle_web/Bernoulli.html#:~:text=Since%20the%20velocity%20at%20the,occurs%20at%20the%20stagnation%20point. 2600:1700:2BB0:6AB0:81F9:19C:66E2:EF69 (talk) 18:36, 20 December 2023 (UTC)
thread_title:  Necessary Revision