Is circulation real?

Unlike the academics in both engineering and science, and the aerospace professionals that I have failed to sway with my arguments, I am blessed by having no professional or academic credibility in the field to protect: nor any commercial or economic investments to protect, I am invulnerable to the risk of being labeled crazy.
I am aware that I am in the fortunate position of being fascinated by the subject, just educated enough in maths and physics, just smart enough to put together an argument, with the time and resources to devote to the subject and entirely unfazed by being labelled crazy by those with so much invested in the field to consider rocking the boat.
I still may be wrong, but until the objections transition from abuse, accusations of ignorance and weakness of mind to ones of science, experiment and logic, I will persevere and welcome any support I can get.

 

Here's my view of the the problem.

Fluid mechanics addresses the continuum realm.
Statistical mechanics* addresses in the molecular-kinetic realm.
Aerodynamics resides in the "no man's land" between the two.

Velocity has a meaning when applied to weather systems, clouds and wind. It can be measured by anemometers, pitot tubes, timing of visual clues like smoke and clouds. Fluid velocity is the core of fluid dynamics. from Bernoulli, Euler through Navier Stokes and Kutter-Joukowski and CFD.
Velocity has a meaning when applied to molecules and in statistical mechanics. It can be measured in the lab in a vacuum chamber, a vapour source, two spinning disks and a particle detector. It can be used in Newtonian mechanics to explain pressure and temperature.

Velocity is at the core of fluid dynamics.
Velocity is at the core of kinetic theory and statistical mechanics*.

Since there's no gedanken to identify velocity in the no man's land where aerodynamics operates, it has no meaning.
Planes fly, birds fly, yachts sail, propellers work, wind turbines work.
No one can Explain Why Planes Stay in the Air because fluid dynamics and statistical* mechanics cannot reconcile their concept of velocity.
[EDIT] *I have probably complicated the issue by referring to statistical mechanics and should have stuck with classical, i.e. Newtonian mechanics.[/EDIT]

 

Velocity is well defined: length/time. It has the same meaning in statistics, fluid dynamics, etc. There is no need to reconcile any concepts. It is the same for all.

 

Very reduced vision of the concept of speed.
Speed: change of the value of a variable with time?.

 

That is the standard definition.

 

Velocity is speed with a direction.
Speed is length/time

While people use velocity and speed interchangeably, they are not the same. Gonzo, you know this as you have mentioned this in other posts and threads.

The reason that I am trying to clarify this is that on the windward side of a sail,
the SPEED of the air coming into the sail at say x degrees to the tangent (direction) of the leading edge of the sail, so a speed and a direction, ie a velocity. **** But if the air exits the sail trailing edge at the same Speed BUT at a change of direction of Y degrees to the tangent of the leading edge of the sail. Ie a new direction.

There will be a quantity of mass of the air that has undergone the change in direction.

A change in the direction is a change in velocity and hence an acceleration.
So Newton F=Mdot x a and hence this the lift force that acts on the sail

Again windward side.

This is basic vane mechanics.

Summary, a given quantity of mass has its direction changed, accelerated, and this produces a force.

**** This is a bit of a simplification wrt to the air direction coming into the sail as the forward velocity of the boat influences the combined wind direction. Ie I am using these simplified terms as if the sail were a fixed vane.

 

You are correct.

 

Now that we are in agreement about the meaning of velocity, maybe we can we return to the core problem.
The symbol "v", meaning velocity, that appears in the continuum (fluid dynamics) realm and the "v" that appears in the molecular-kinetic realm (classical mechanics) both refer to the motion of the fluid, but of entirely different stuff.

The "v" used in aerodynamics to explain lift, drag, thrust, leeway/heel, power, work etc. also refers to the motion of the fluid, in this case air, but fails because there's no consensus about what it is being measured.
Wind blows at around 15 kts, molecules move at around Mach 1.
The topic becomes further mired by the fact that aerodynamics is about the interaction between the air and a solid (wing, sail, prop, turbine), which is also moving.
Hence my summary above about the failure of aerodynamics in that it cannot reconcile the fluid dynamics velocity and classical mechanics velocity.
@Barry's explanation above #666 (!devil's number!) encapsulates the problem:
"So Newton F=Mdot x a and hence this the lift force that acts on the sail."
"a" is acceleration, the time rate of change of v, but velocity of what? The molecules or the air?
"M" is mass, but of what, the molecules or the air? If molecules - how many? if air - what volume?
It really doesn't work because there's no "Thought experiment" that can answer these questions.

 

I do not really care about the molecular speed or velocity of molecules. (though the speed/velocity of gas molecules in an enclosed chamber determines pressure) In many years of post secondary education, NEVER in analysis of all things moving, gasses or liquids has the velocity of molecules EVER entered into the discussion.

For speed of the air, a simple pitot tube will tell me what the speed is and the orientation of the pitot tube, orientating it so that the speed is at max ( which will give me a direction) ( yes, the pitot tube measure pressure, so I will say that the pitot tube assembly/computer etc, just gives you a read out in mph, kmh, feet per second or what ever. The pitot tubes on air planes and boat transducers gauges read in speed)
As air moving into a sail is not constrained in a pipe, or other boundary layer constriction, except at the sail, ie the wind at the interface of the sale is at a boundary layer.
M dot, is a mass flow rate, so x pound mass per second, minute etc

Sailor Al "a" is acceleration, the time rate of change of v, but velocity of what? The molecules or the air? Reaching for confusion??? In F=mdot a the acceleration relates too what mass you are moving. Ie if you are moving 1000kgm at
per hour etc.

Sailor Al " M" is mass, but of what, the molecules or the air? If molecules - how many? if air - what volume? Reaching for confusion??? It is fundamental that the mass is the mass whose velocity is impacted by the sail.

This is fundamental physics.

Sailor Al It really doesn't work because there's no "Thought experiment" that can answer these questions. What does not work?? I am not considering a "though experiment" More ambiguity.

Sailor Al The topic becomes further mired by the fact that aerodynamics is about the interaction between the air and a solid (wing, sail, prop, turbine), which is also moving. If you take the time to read my previous post, you will note that
I tried to simplify the explanation to keep it to " Grade 12 physics" which you refer to being able to explain complicated processes. There are proven (by people, PHD"s experimenting with such things, NASA, and current, not 200 year old experimenters ) formulas to used to evaluate your items above.

Sailor ALHence my summary above about the failure of aerodynamics in that it cannot reconcile the fluid dynamics velocity and classical mechanics velocity. But yet, man has put people into space, airplanes fly, etc etc and used proven
formulas to make this happen. This is not about they guy who glued wings onto his back and jumped off a cliff. Icarus maybe?

 

You are offering the equation F=Ma to explain the aerodynamic force. I’m saying that since the variables M and a cannot be identified by physical or thought experiments, the formulation has no validity.

 

M can be easily identified by measurements or derived from observed behavior. An airplane is kept flying by the reaction force of the wings on the air, and the vertical component of the engines thrust. No mystery there. Any "formulation" is validated by empirical results. Airplanes fly, therefore it is valid.

 

Thank you. Mystery solved.
Just one thing. Could I trouble you for a quick sketch of how @Barry ’s M (mass of air being accelerated) is measured?
Oh yes, and a quick estimate of the vertical thrust component of an aeroplane engine?

 

Indeed.
When I do my hydrostatic and hydrodynamics analysis, or when I am designing structures do I think...ok, what are the covalent bonds or the Vanderwaal forces going on in the atoms of the medium I am using. ...er...no!

Otherwise, "leaps" forward in science/engineering would not occur, as one is stuck at the molecular level and not being able to take a holistic view of the situation at hand.

And how do you "think" in your thought experiments of infinity?
How do you understand and explain and imagine infinity...

 

It was precisely my thoughts on infinity that led me here, specifically my thoughts on the infinitesimal ... the calculus of the limits as x approaches zero that made me aware of the failings of the use of calculus to solve the problems of fluid dynamics.
The "proof of the pudding" is that there is no meaning to the velocity vector "u" in the N-S equation (attached).
As you may recall, last year I spent many posts pressing forum members for experimental evidence of the existence of air velocity increase over aerofoils. None were forthcoming. None can ever be forthcoming. At the scale of air velocity over airfoils, the concept of velocity itself becomes meaningless.
Abstruse FD papers refer to the coalescence of macroscopic and molecular perspectives, undermining the current foundations of continuum fluid mechanics the two context-specific velocities: mass-velocity and volume-velocity.
Technospeak for the velocity of the air and the velocity of the particles.

I have attached Brenner's rather lugubrious anecdote of Einstein's response to Weissenberg which I have condensed to :
"the only mechanism by which one could understand the meaning of a mathematical symbol in a theoretical equation was by the mental exercise to experimental determination of that entity."

There's a management truth: "If you aren't measuring it, you you aren't managing it." which can be restated to match Einstein's advice: "If you can't measure it, you can't use it in an equation."

Holistic approaches may work in sociology: they don't work in the hard sciences.

Since the nature of the velocity vector cannot be identified, the N-S equations have no meaning.

@Barry says he never thinks about the molecules. What does he think provides the M in his "So Newton F=Mdot x a"?

 

To me, this sums up your whole dilemma that exists in your mind - definitions and comprehension!

Holistic - in this context - means considering a whole thing to be more than a collection of individual parts.
It has nothing to do with sociology. That is just another obfuscation to change the narrative.

You struggle with definitions and attempt to change the narrative to suit your own interpretation, despite endless evidence to the contrary.
Your failure to comprehend, is not a failure of a theory...only your failure to comprehend.

So, consider this.
There are just 2 possible outcomes here.

1. You have discovered a whole new realm of science previously undiscovered that no one can explain. (Great good for you.....)
or
2. What you seek exists, but you are unable to understand it when presented, or merely that the 'evidence' you seek, requires a far far more nuanced approached than high-school maths.

And finally, .....which ever it is, it wont make you a better/faster sailor, as your whole MO has set out to be.
Since either those that sail against you and beat you..either know what you seek, or, it matters little to them as sailing, like many things in life, to excel one must take a more holistic approach.
Rarely in life is there one sole attribute that leads one to an equally simple solution/answer.