According to Bernoulli's Equation or Effect, fluid flows faster when the pressure is lower. How???

Question

If high pressure increases velocity of fluid, how does fluid flow faster when the pressure is lower?

Answer 1

Fluids have three ways of storing energy: temperature, pressure and velocity, and those are interchangeable (for instance, an aerosol can will exhange the compressed gas pressure and temperature energy for velocity: when using it, the velocity will increase and the temperature and pressure will drop).
For the Bernouilli principle, this is exactly whay is happening. If you want to go faster withough adding energy to the system, the pressure has to drop -- that is how airplane wing work, the air above the wing has to go a bit faster because of the curvature and that creates a lower pressure, which "succion cups" the wing up. And the effect is also available in reverse: lower the pressure actively, like with a vacuum cleaner, and the air will accelerate (evidently, that is how you get it to go in the vacuum cleaner in the first place).
Higher pressure icreases velocity if you add it at first, that means add energy to the system. As long as you only add pressure without allowing the fluid to expand that pressure and turn it into velocity (hence allowing to undergo a pressure drop) you will not get motion. Or you can lower the pressure downstream (like with the vacuum cleaner).

Answer 2

it extremely is in basic terms Newton's regulations of action, utilized to a fluid. If something speeds up, there's a tension appearing on it. start up via questioning approximately an incompressible fluid like water. Bernouilli's equation applies in basic terms as nicely to that, different than you will not get perplexed via the undeniable fact that air is compressible (which doesnt' make any actual distinctive to what Bernouilli pronounced). If water is flowing by way of a pipe that variations is flow-section section, the fee could desire to be bigger whilst the section is smalller, using fact an analogous quantity of mass according to 2d (and subsequently an analogous quantity of quantity according to 2d ) is passing each element alongside the pipe. There could desire to be some tension that's accelerating the water whilst the pipe gets smaller, and decelerating it whilst the pie gets extra advantageous. That tension is the substitute in water tension. What Bernouilli did grew to become into re-write Newton's regulations of action in terms of tension and density, not tension and mass. it extremely is probably not a "new" theory of physics in any respect. For compressible fluids (e.g. gases) you elect some extra tips approximately how the gas behaves to extremely calculate the variations in tension and velocity, using fact the strain (tension) may additionally do artwork changing the temperature of the gas. Bernouilli's theory would not say something approximately a thank you to do those extra advantageous calculations. yet for many circumstances the place the flow velocity is under the fee of sound (say as much as approximately 2 hundred mph in the earths environment at sea point) Bernouilli's theory supplies extraordinarily stable consequences despite in case you assume the air is incompressible.

Answer 3

A common model to demonstrate the law of Bernoulli is a convergent / divergent nozzle, the Venturi Tube usually just called a venturi. This is a large diameter tube, gradually feeding into a smaller diameter tube and then again gradually into another larger tube.

As a gas or fluid medium flows through the venturi the total pressure is constant across the entire cross section and the entire length of the tube, save for some friction losses. From the same total pressure on both ends of the convergent section and different cross sectional areas at the inflow and outflow end of this section follows a net force that accelerates the medium in the general direction of flow.

In addition to this acceleration, the medium is also forced to change the direction of flow as it enters the convergent section and again as it leaves the convergent section and enters the smaller diameter tube. The changes in direction imply additional acceleration normal (orthogonal) to the direction of flow. The necessary forces are provided by the wall of the tube and result in a change of static pressure. Upon entering the convergent section the direction of acceleration is such that the pressure increases. Upon leaving it, the direction of curvature is reversed, resulting in a pressure decrease. Since the medium is flowing faster at the latter point, the amount of pressure decrease is larger than the initial increase. This mechanism for pressure change establishes a direct link between flow velocity and change in static pressure. Thus the net difference in static pressure between the large diameter tube and the small diameter tube is directly related to the change in velocity between these two sections, which is expressed mathematically with Bernoulli's equation.

The divergent section at the outflow of the small diameter tube presents a reversed situation regarding the cross section areas. Therefore here exists a net force working against the flowing medium, forcing it to slow down and to gradually assume the static pressure in the larger diameter tube.

It is important to stress that the mechanisms described here only exist in the Venturi Tube and therefore represent a special case for the application of the Bernoulli's law. Acceleration in a free stream (not bounded by walls) can only happen due to differences in pressure and will follow Bernoulli's law.

Static pressure = pressure in a medium e.g. atmospheric air pressure (also referred to as head)
Dynamic pressure = pressure due to motion.
Total pressure = sum of static and dynamic pressure