Bernoulli Principle?

Question

Can anyone explain to me about Bernoulli Principle?

Answer 1

A fluid in steady motion has energy due to (1) static pressure & (2) dynamic pressure, or kinetic energy due to motion of the fluid. Daniel Bernoulli showed that for an ideal fluid the total energy in a steady streamline flow remains constant, i.e. static pressure energy + kinetic energy = Constant total energy. The energy can change from one form to another but the total must remain the same. If the dynamic energy is increased by increasing the velocity of the fluid flow (for example, over the upper surface of an aircraft wing because of its shape) the static pressure must be reduced to compensate. The static pressure beneath the aircraft wing is not reduced and hence lift.

Answer 2

The Bernoulli principle states that an ideal fluid flowing in an enclosed system with no work being performed must maintain a constant internal energy. That is, the sum of the kinetic, potential, and pressure energies must be the same at all points in the system. Therefore, if any one form of energy is increased, another must be equally decreased. Therefore, if the velocity increases, then the pressure must decrease. Or if the flow were downhill, the loss of potential energy could result in the increase in the kinetic energy.

See the link below for a more in-depth discussion of the Bernoulli principle, including the equation when work is performed on or by the fluid and the differences in the equations when the fluid is compressible or incompressible.

Answer 3

At the top of each vertical pipe, the pressure is 1 atm. But your use of it in Bernoulli's equation is incorrect. You need to get the concept right. Start with: Pt = Ps + ρv²/2, where: Pt = Total, or stagnation pressure. In the absence of viscous or mixing losses, it is constant along the flow path, as you seem to indicate. Ps = static pressure, the pressure the fluid particles sense as they merrily flow on their collective way. This can and does change. ρv²/2 = dynamic pressure this is a calculated pressure. So, at 1: Pt = Ps1 + ρv1²/2 at 2: Pt = Ps2 + ρv2²/2 at 3: Pt = Ps3 + ρv3²/2 and, Ps1 = 1 atm + ρgh1 Ps2 = 1 atm + ρgh2 Ps3 = 1 atm + ρgh3 Now, subtract Bernoulli's equation at 1 from that at 2 and you can get v2^2 - v1^2 = 2g(h1 - h2). That is, as the heights differ between two stations, so do the velocities.

Answer 4

Fast moving air creates low pressure. The faster it moves the lower the pressure. This is what creates lift on an airplane wing. As the air molecules are seperated by a plane's wing, those passing over the top of the wing have to travel faster to keep up with those passing underneath since the top is curved making it slightly longer than the straight bottom.

Another way to look at it is that the curvature of a lifting body (i.e. wing) separates the molecules a bit more than the straight bottom. Since the molecules are seperated, there is less of them per unit area, making them less dense. Since the air on the bottom of the wing is more dense then that on top of the wing, those molecules lift the wing up.

Answer 5

the bernoulli principle states that the total mechanical energy(pressure,kinetic,potential) is always conserved. fluid is (the fluid is considered to be non viscous).

Answer 6

The air moves faster over the larger rounder top surface of the wing, creating a partial vacuum (less pressure on the top and more on the bottom) which equates to 'lift'.