## Sunday, February 05, 2006

### Bernoulli's Law - definition - fluid dynamics

Definition: A statement of the conservation of energy in a form useful for solving problems involving fluids. For a non-viscous, incompressible fluid in steady flow, the sum of pressure, potential and kinetic energies per unit volume is constant at any point.

p + qv2/2 + qgy = constant

where p is the pressure, q is the density, v the velocity and y the height in a gravitational field of strength g, all measured at the same point. This quantity is then constant throughout the fluid.

Bernoulli's principle is used for, but not essential to, lift by airplanes.

Also Known As: Bernoulli’s Principle

Common Misspellings: Bernouli’s Law, Bernulli’s Law, Bernolli’s Law, Bernoulis Law, Bernullis Law, Bernollis Law

Examples: A special case of the Bernoulli equation is when the height of the flow remains constant. i.e. the third term disappears from the equation. This reduced form shows that if the pressure in a fluid decreases, the flow will accelerate and vice-versa. The Bernoulli family have made many contributions to science and mathematics, including probability theory.