# Bernoulli and Low Pressure

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Just a quick question for all you pros out there. Is it safe to say that with the reduced pressure on the upper surface of the wing, (Bernoulli) this low pressure area is akin to a vacuum of sorts??? I think so. Thoughts

vac⋅u⋅um
1. a space entirely devoid of matter.
2. an enclosed space from which matter, esp. air, has been partially removed so that the matter or gas remaining in the space exerts less pressure than the atmosphere (opposed to plenum ).​

Strictly speaking, I would say no, because all the definitions for "vacuum" appear to require an enclosure or container. I would call the air on top of a wing "a region of relatively low pressure."

In my opinion, no.

Vaccuums are created in an entirely differently manner than a lower pressure caused by the flow of air over a curved surface.

You cannot create a vaccuum over a curved surface through the acceleration of air.

Doh! seconds late.

Vaccuums are created in an entirely differently manner than a lower pressure caused by the flow of air over a curved surface.

Some of the best vacuums meatbags have been able to produce have been done with a u-haul on the shuttle.

http://en.wikipedia.org/wiki/Wake_Shield_Facility

(Oh wait! I just contradicted my interpretation of a vacuum! Well, they don't call it a vacuum. )

How do you explain the carbeurator's function, if it doesn't create a vacuum?

How do you explain the carbeurator's function, if it doesn't create a vacuum?

Ahhhhhh! now there is a question to ponder.

And try this on for size. If the low pressure on the upper surface of the wing is not a vacuum of sort, then the predominant lifting force is then the high pressure on the lower surface. I'm of the volition that the predominant lifting force is the low pressure upper surface (pulling the wing up) aided by the high pressure on the lower surface!!!

How do you explain the carbeurator's function, if it doesn't create a vacuum?

The high-speed air creates a pressure differential, which causes fuel to be pushed from a circuit into the airflow ... just like a fuel injector (except for how the pressure differential is produced).

I was just saying that all the dictionary definitions seem to require an enclosure to officially be a "vacuum" ... i.e., there a physical barrier that prevents fluid from flowing a high pressure region to a region of low pressure.

agreed its pressure differential, not a vaccuum

all the dictionary definitions seem to require an enclosure to officially be a "vacuum" ... i.e., there a physical barrier that prevents fluid from flowing a high pressure region to a region of low pressure.

Dictionary definitions are not very reliable when it comes to scientific terms. What physical barrier ensures the vacuum of outer space?

Dictionary definitions are not very reliable when it comes to scientific terms. What physical barrier ensures the vacuum of outer space?

Good point

Pressure differential is a better way to think about it. What if both sides of the wing were shaped exactly the same way? Would the "vacuum" exist? I like teaching pressure differential.

Pressure differential is a better way to think about it. What if both sides of the wing were shaped exactly the same way? Would the "vacuum" exist? I like teaching pressure differential.

"Pressure differential" is the only meaningful concept. "Vacuum" is an imprecise, relative term. A total vacuum on two sides of a plate will generate no force. If you have slightly less "vacuum" on one side of the plate with respect to the other, a force will be generated.

Likewise, there is no real existence of "suction"; it's just an area of pressure lower than surrounding pressure.

"Pressure differential" is the only meaningful concept. "Vacuum" is an imprecise, relative term. A total vacuum on two sides of a plate will generate no force. If you have slightly less "vacuum" on one side of the plate with respect to the other, a force will be generated.

Likewise, there is no real existence of "suction"; it's just an area of pressure lower than surrounding pressure.

Again... This then points to the high pressure on the lower surface being the driving force of lift. It says to me that because there is a lower pressure above the wing, then it's all about Newton pushing up through said low pressure of Bernoulli.

I'm lost. I've never heard or read about Bernouli and Low/High Pressure being associated with Carburetors. Could someone flesh it out some more for me?

Again... This then points to the high pressure on the lower surface being the driving force of lift. It says to me that because there is a lower pressure above the wing, then it's all about Newton pushing up through said low pressure of Bernoulli.

Pressure is a Newtonian effect....it's the momentum transfer of molecules hitting something.

But, again, it's meaningless to say the high pressure on the bottom is the "driving force" for lift. Did you know that at low AoA, the pressure is negative on BOTH sides of the airfoil? Which then is the true source of lift?

"Pressure differential" is the only meaningful concept. "Vacuum" is an imprecise, relative term. A total vacuum on two sides of a plate will generate no force. If you have slightly less "vacuum" on one side of the plate with respect to the other, a force will be generated.

Likewise, there is no real existence of "suction"; it's just an area of pressure lower than surrounding pressure.

Again... This then points to the high pressure on the lower surface being the driving force of lift. It says to me that because there is a lower pressure above the wing, then it's all about Newton pushing up through said low pressure of Bernoulli.

This then points to the high pressure on the lower surface being the driving force of lift.

Except when you don't have one.

I'm lost. I've never heard or read about Bernouli and Low/High Pressure being associated with Carburetors. Could someone flesh it out some more for me?

The incoming air gets sped up through the venturi and creates an area of lower pressure that sucks the fuel out of the reservoir and into the engine. The air through the venturi is of lower pressure that the fuel in the reservoir (same concept as lift/Bernoulli)

The incoming air gets sped up through the venturi and creates an area of lower pressure that sucks the fuel out of the reservoir and into the engine. The air through the venturi is of lower pressure that the fuel in the reservoir (same concept as lift/Bernoulli)

SUCKS Equals VACUUM

SUCKS Equals VACUUM

actually, it doesn't. but you seem to be pretty stuck on teh suck, so....

good luck in getting the answer you want to hear.

SUCKS Equals VACUUM

I forgot these guys """"

I know exactly what you mean, that area of lower pressure only "exists" because of that area of higher pressure below, but technically sucks doesn't mean vacuum. It seems to suck but in reality it's just the area of higher pressure trying to get into that area of lower pressure.

Dwell on this......imagine you're in a room with your complaining/whining gf/wife/bf whatever. Let's call the room an area of high pressure or the bottom of the wing, now, imagine you look at the door(the wing), and the hallway on the other side is the area of low pressure or the top of the wing. Now we all know it's impossible to be "sucked" out of that door, but because you are in that room of high pressure, you would much rather be in that hallway away from all the complaining(area of low pressure) and start to move towards that area for relief. As you open the door, you(the area of high pressure) opens/pushes the door open into the area of low pressure(this is the lift part) You chose to leave the room to go into the more comfortable hallway which is "sucking" you out....BTW, this in the end leads you to the street, which inevitably leads you to the bar. The bar, by your definition, would be considered a real vacuum because, let's face it, it sucks you in......

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