Bernoulli's Principle

In an irrotational fluid, the sum of the static pressure, the weight of the fluid per unit mass times the height, and half the density times the velocity squared is constant throughout the fluid. Bernoulli’s equation expresses the energy conservation in the fluid.

The pressure in a fluid decreases as its velocity increases.

where:

P = pressure [Nm^-2]

ρ = density [kgm^-3]

v = velocity [ms^-1]

h = elevation [m]

g = acceleration due to gravity [ms^-2]

This is the basis by which a wing produces lift:

See also: Pressure, Velocity, Venturi.