Bernoulli’s Principle

A mathematical relationship between the pressure of a fluid and its elevation and its velocity. This principle explains why a moving stream of liquid or gas exerts less pressure than if it were at rest. Bernoulli’s equation can be used to approximate flow parameters in water, air, or any fluid stream that has very low viscosity.

For example, given two points along a streamline, or an imaginary line tangent to the direction of flow, the Bernoulli equation states:

P₁ + ½ ρv₁² + ρgh₁ = P₂ + ½ ρv₂² + ρgh₂

where v is fluid velocity; ρ is fluid density; h is relative height; and P is pressure.