Is circulation real?

No, I don't have any requirement for any type of circulation.
It was Kelvin who defined circulation as the integral of a vector field around a closed path that moves with the fluid. With that in mind, he developed the theory of circulation that
identified a physical law that the circulation of an ideal fluid subject only to conservative forces was conserved over time.
It was the aerodynamicists since Prandtl who have mis-applied Kelvin's principle to a circulation around a path that moved with the wing.
I quote from Prandtl's 1922 paper to NACA where, in Part II , on p 181 with reference to fig 32. (below),

he states :

By drawing the circulation line surrounding the wing, he is clearly using a concept of circulation around the wing. However, by using Kelvin's theorem of conservation of circulation, he is clearly referring to Kelvin's definition of circulation as the integral around a path pinned to the flow.

 

I’m revisiting the standard circulation derivation of lift as presented in Clancy (Aerodynamics, 1975), specifically the argument around pp. 156–157 and Figs. 7.28–7.29.
In Fig. 7.28, a region C′ is considered in which the usual assumptions (inviscid outer flow, no body forces, etc.) apply. In Fig. 7.29, the region is modified, but it now encloses a solid body that exerts a force resisting the motion of the surrounding fluid.
My difficulty is this: once the region contains a body that exchanges force with the fluid, the region is no longer force-free. The assumptions used in Fig. 7.28 therefore do not obviously carry over to Fig. 7.29 without an additional term.
Put more concretely:
when the integration region is altered to include the body, where is the body–fluid interaction force accounted for in the balance?
If it is treated as a boundary traction, then the equivalence of the two regions needs to be made explicit. If it is not, then the contour deformation appears to change the physics.
I’m not questioning the empirical reality of lift, only whether this particular derivation is internally self-consistent.

 

Carlos constantly hijacks threads with nonsense. He claims to be superior to the rest of the world and only he can understand physics.

 

And the older the thing you quote the more authorative it is apparently.

 

I’m still looking for an answer to the specific question above.
If someone believes the body–fluid interaction is already accounted for in the standard derivation, I’d appreciate being shown where that term appears when the integration region is altered to include the body.
If it does not appear explicitly, then the justification for omitting it is the point I’m trying to understand.

 

You know....something about the persistent obliquity of Sailor A"I"or lower case "L" just struck me. Sailor A (artificial) I (intelligence).... Is Sailor A"I" a "L"LM? Large language model - Wikipedia https://en.wikipedia.org/wiki/Large_language_model.

From the wiki page

This thread started in 2013.... Sailor A..."L"... joins in 2021

 

For the record, Sailor Al is just me: a sailor named Alan.
In any case, I’m still looking for engagement with the technical question above regarding where the body–fluid interaction force enters the balance when the integration region is deformed to include the body.
If someone thinks that term is already accounted for implicitly, I’d appreciate being shown where.

 

Say that with an Australian accent to prove you are not a robot.

 

I’m not here to perform party tricks.
If anyone would like to address the technical question already stated, namely where the body–fluid interaction force enters the balance when the integration region is deformed to include the body, I would welcome that.