Quote:
Originally Posted by JulianEdgar
You do realise that the diagram you nominate is for inviscid flow?
That is, it's for for an imaginary fluid having no viscosity?
You did read the description on the next page that states:
In the real, viscous flow there exists a drag force, but it cannot be explained by considering an ideal, inviscid fluid.
If you are using this diagram - and others with similar concepts - no wonder your theory is so divorced from the reality of car aerodynamics.
Addition:
In fact, for people interested in seeing how confusion (and weird theories) can develop, it's worth having a good read of pages 51 and 52 of Hucho, second edition. It explains really clearly how a simplified aerodynamic model (ie non-viscous fluid) cannot be used to explain what happens on real cars.
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1) Free flow, outside the boundary layer IS considered inviscid flow.
I stated that we're looking at 2-D flow. Which is basically what your looking at when you do your centerline pressure profiles.
2) And of course, we don't live in a d' Alembert's Paradox world of non-viscosity.
3) The value of the schematic, was the example of a body experiencing positive pressure downstream of 'lift', which is germane to streamlined bodies.
4) You like wings, Hucho goes on elsewhere to show the same thing for a RAF 101 symmetrical airfoil, at 4-degrees angle-of-attack, and zero lift. This is a real foil in a real laboratory, and real air, at supercritical Reynolds number.
5) And as I shared with you many months ago, Abbott and Von Doenhoff's book demonstrates zero-lift conditions for every extant airfoil known at the time of their publication. Your aeronautical engineer friend will have that. My aeronautical engineer friend Larry Mauro does.
' The drag and lift of a body depend strongly upon the angle of attack.' Hucho, page 202, Re: Stollery & Burns Ref. 4.83.