/sci/ - Science & Math » Thread #11928309

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Everyone is lying to me

Anonymous Thu 23 Jul 01:08:51 2020 No.11928309 View Reply Original Report

Quoted By: >>11928684 >>11928715 >>11929112 >>11931919 >>11932152 >>11935638

If the Bernoullian and Newtonian Theories on the generation of lift are incorrect, how is lift really generated?

Anonymous

Anonymous Thu 23 Jul 2020 03:23:04 No.11928684 Report

Quoted By:

>>11928309
>He doesn't lift

Anonymous

Anonymous Thu 23 Jul 2020 03:33:56 No.11928715 Report

Quoted By: >>11928813 >>11929424

>>11928309
>If the Bernoullian and Newtonian Theories on the generation of lift are incorrect
They're not incorrect exactly, they just don't tell a complete picture of aerodynamic lift.

>how is lift really generated?
If you have a plate with a particular cross-section and angle it against an incoming air flow, then the plate will generate lift and drag. If you know the plate area, flow properties, and angle of the plate relative to the flow, then you can derive an empirical model explaining how that exact cross-section generates lift. The empirical nature of understanding lift is the source of the issue, or rather there hasn't been an physical model of lift that matches the empirical model with satisfactory results.

t. Aerospace Engineer

Anonymous

Anonymous Thu 23 Jul 2020 03:35:37 No.11928720 Report

Quoted By: >>11929938

The wing deflects air downwards. That pushes the wing upwards. The specifics about the flow field are governed by Navier Stokes, but that's the general idea

Anonymous

Anonymous Thu 23 Jul 2020 03:45:15 No.11928742 Report

Quoted By:

Kutta-Jukowski theorem:
$\Gamma\equiv\oint_C v\cdot\text{d}s\ ; \ \text{Lift per unit span}=-\rho_\infty V_\infty\Gamma$
rho and V are upstream density and velocity

Anonymous

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Anonymous Thu 23 Jul 2020 03:46:23 No.11928746 Report

Quoted By:

Kutta-Jukowski theorem:
$\Gamma\equiv\oint_C v\cdot\text{d}s\ ; \ \text{Lift per unit span}=-\rho_\infty V_\infty\Gamma$
rho and V are upstream density and velocity, gamma is known as circulation.

Anonymous

Anonymous Thu 23 Jul 2020 04:14:18 No.11928813 Report

Quoted By:

>>11928715
>If you have a plate with a particular cross-section and angle it against an incoming air flow, then the plate will generate lift and drag. If you know the plate area, flow properties, and angle of the plate relative to the flow
This is insane because you can actually try it with a coin on a table

Anonymous

Anonymous Thu 23 Jul 2020 05:29:57 No.11929112 Report

Quoted By:

>>11928309
>how is lift really generated
Coanda Effect

Anonymous

Anonymous Thu 23 Jul 2020 07:32:41 No.11929424 Report

Quoted By: >>11929924

>>11928715
So if I have zero angle of attack, there is no lift?

Anonymous

Anonymous Thu 23 Jul 2020 08:12:06 No.11929530 Report

Quoted By:

People think that shorter distance means less surface area. They are wrong so, they think that Bernoulli is.

Anonymous

Anonymous Thu 23 Jul 2020 11:45:48 No.11929924 Report

Quoted By:

>>11929424
If you have a symmetric cross section with zero angle of attack, there is no lift. Nonsymmetric cross sections (such as airfoils) do generate lift at zero angle of attack

Anonymous

Anonymous Thu 23 Jul 2020 11:53:40 No.11929938 Report

Quoted By: >>11930552 >>11930625

>>11928720

>The wing deflects air downwards. That pushes the wing upwards.

This.

Anonymous

Anonymous Thu 23 Jul 2020 16:06:31 No.11930552 Report

Quoted By:

>>11929938
how

Anonymous

Anonymous Thu 23 Jul 2020 16:12:24 No.11930563 Report

Quoted By:

https://fermatslibrary.com/s/how-airplanes-fly-a-physical-description-of-lift

Anonymous

Anonymous Thu 23 Jul 2020 16:40:57 No.11930625 Report

Quoted By: >>11931841

>>11929938
Air hits wing
Air pushed down by shape

Anonymous

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Anonymous Thu 23 Jul 2020 22:38:12 No.11931841 Report

Quoted By: >>11931880

>>11930625

Anonymous

Anonymous Thu 23 Jul 2020 22:48:11 No.11931880 Report

Quoted By: >>11933038

>>11931841
This was explained to me as a pressure differential, the fast moving air above has lower pressure than the air on the bottom. No idea if that's right though.

El Arcón

El Arcón Thu 23 Jul 2020 22:54:38 No.11931902 Report

Quoted By:

>how is lift really generated?
At first, air is not moving vertically. Then a wing comes along some air is forced downward due to the angle of attack of the wing. When the wing exerts a force on the air making it go down, the air exerts a force on the wing making it go up. This is the lift force.

Anonymous

Anonymous Thu 23 Jul 2020 23:02:17 No.11931919 Report

Quoted By:

>>11928309
No matter how it happens, air must be deflected downwards by the wing. This si the only way for it to obey Newton's theirs law. Wether the air is selected by pressure differences or directly by the wing I don't know, but I figure this needs to be mentioned

Anonymous

Anonymous Fri 24 Jul 2020 00:47:40 No.11932152 Report

Quoted By:

>>11928309
Given the shape of an airfoil, particularly the teardrop shape, due to viscosity, in the trailing edge a vortex is generated when the relative motion between air and airfoil begins. As speed increases the vortex then detaches from the wing as still due to viscosity effects; as this happens an equal and opposite vortex is generated around the wing, which causes the difference in speed of the flow between lower and upper side, with subsequent difference in pressure, hence lift is generated.

t. Aerospace engineer

Anonymous

Anonymous Fri 24 Jul 2020 01:02:58 No.11932178 Report

Quoted By: >>11933790

just get a small scale wing or plate or some shit.

put it parallel to ground. shit no lift.

angle it some way. damnit

go get in a car

go 60mph

stick plate out window parallel to ground

hmmm no lift

now angle it up ever so slighty

it is now become lift. it is no longer in your hand most likely.

Congratulations. you have made empirical observation.

speed + angle + wing+object = lift

Anonymous

Anonymous Fri 24 Jul 2020 09:02:49 No.11933038 Report

Quoted By:

>>11931880
Thats right.

Anonymous

Anonymous Fri 24 Jul 2020 15:33:17 No.11933790 Report

Quoted By:

>>11932178
>empirical
Fluids always triggered my autism. Why can’t we eveer have nice equations?

Anonymous

Anonymous Sat 25 Jul 2020 02:14:32 No.11935638 Report

Quoted By:

>>11928309
the newtonian is right tho. only retard pseuds ever believed the bernoulli retardation. I didnt even believe it in highschool (neither did i believe the glass is liquid meme my pyshics teacher told me)

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