Talk:Stagnation pressure

From Wikipedia, the free encyclopedia

	Portal This article is within the scope of WikiProject Physics, which collaborates on articles related to physics.
Stub	This article has been rated as Stub-Class on the assessment scale.
???	This article has not yet received an importance rating within physics.
Help with this template This article has been rated but has no comments. If appropriate, please review the article and leave comments here to identify the strengths and weaknesses of the article and what work it will need.

This article has been automatically assessed as Stub-Class by WikiProject Physics because it uses a stub template. If you agree with the assessment, please remove {{Physics}}'s auto=yes parameter from this talk page. If you disagree with the assessment, please change it by editing the class parameter of the {{Physics}} template, removing {{Physics}}'s auto=yes parameter from this talk page, and removing the stub template from the article.

I don't understand why the thermal form of stagnation pressure is presented here. Stagnation pressure is the pressure a moving fluid would have if it is stagnated or stopped. It is difficult to clearly communicate this in a formula that makes no reference to velocity. Stagnation pressure is constant in an eisentropic flow. P_s = P + ρv² where P_s is the stagnation pressure, P is the pressure at a given velocity, ρ is density and v is velocity. Granted that any change in v must be accompanied by a change in temperature T, but to someone that is un initiated in the art of fluid dynamics this is probably not obvious. This is especially true when working with an incompressible fluid such as water.

Adding heat to a moving gas at constant pressure and velocity reduces its density and stagnation pressure. Conversley cooling a moving gas at constant pressure and velocity has the oposite effect. US Patent 5,083,429describes a device that uses this effect to extract power. .—Preceding unsigned comment added by Commdweeb (talk • contribs) 13:55, 11 October 2006 (UTC)

—

It's not a good idea to merge stagnation pressure and ram pressure. They are different concepts. The point needs to be clarified, though, that stagnation pressure in an incompressible fluid and stagnation pressure in a compressible fluid are different. The latter is almost always expressed in terms of the Mach number. See any good book on compressible flow.Petwil (talk) 02:00, 25 January 2008 (UTC)

I removed the tags for the merger of ram pressure to here, since no reasons to do so are provided. Only a reason why not merge. Crowsnest (talk) 21:30, 21 April 2008 (UTC)