Bernoulli Principle: Intuitive Explanation?

In summary, there is an intuitive explanation of the Bernoulli principle based on conservation of energy. This involves picturing the reduced pressure in a venturi tube as a result of the fluid's "arrows of force" striking at a shallower angle due to its movement. This concept can also be applied to understanding the air flow over an airplane wing.
  • #1
Swamp Thing
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I have read and understood the explanation of the Bernoulli principle based on conservation of energy, but what I would like is a more intuitive way of picturing just how the reduced pressure develops in, say, a venturi tube.

I want to be able to mentally track an element of the fluid and see, in my mind's eye, why a "slice" of the fluid flow presses on the walls with less and less pressure as it approaches the narrowest point. Is there an intuitive explanation of this sort?

Edit: I realized that I do not really understand it even in terms of conservation of energy. My problem is with dynamic energy : is it just the kinetic energy of an element?
 
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A description that helps em intuitively grasp the principle is the idea of representing the force of the fluid against an object (like the walls of a Ventury tube) as "arrows of force". If the fluid is sitting still, like perhaps still air at sea level, then the full force of 14lbs/in.2 is applied to the wall of the tube. You could picture the arrows of force pointing directly at the wall.

If the air is moving, the arrows point at an angle. On an airplane wing, these arrows would point at the bottom of the wing at a certain angle (depending on the forward motion of the wing), but they point at a shallower angle, indicating that the air only strikes a "glancing blow" against that side. Striking at a shallower angle means it applies less pressure, just like getting grazed by a fastball won't knock you backwards, while a direct hit could break a bone.
 

1. What is the Bernoulli Principle?

The Bernoulli Principle states that as the speed of a fluid (such as air or water) increases, the pressure exerted by the fluid decreases. In other words, faster-moving fluids exert less pressure than slower-moving fluids.

2. How does the Bernoulli Principle work?

The Bernoulli Principle works because of the conservation of energy. As a fluid speeds up, its kinetic energy increases, and this energy must come from somewhere. In the case of a fluid flowing around an object, the energy is taken from the pressure of the fluid, causing it to decrease.

3. What are some real-life examples of the Bernoulli Principle?

Some common examples of the Bernoulli Principle in action include airplane wings, which are designed to create lift by creating areas of lower pressure above the wing and higher pressure below it. Another example is the flow of water through a narrow pipe, which speeds up and creates a lower pressure area behind the pipe.

4. How is the Bernoulli Principle related to flight?

The Bernoulli Principle is a key principle in understanding flight. As air flows over an airplane wing, the shape of the wing creates a difference in air speed, resulting in a pressure difference that creates lift. This lift, along with other aerodynamic forces, allows an airplane to fly.

5. What are some limitations of the Bernoulli Principle?

While the Bernoulli Principle is a useful concept in understanding fluid dynamics, it is not the only factor at play. Other factors, such as the shape and angle of an object, also play a role in determining the forces acting on a fluid. Additionally, the Bernoulli Principle does not fully explain the lift of an airplane wing, which is also influenced by the wing's angle of attack and the downward deflection of air by the wing.

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