Rayleigh's dissipation function

Rayleigh's dissipation function

[′rā·lē ‚dis·ə′pā·shən ‚fəŋk·shən] (mechanics) A function which enters into the equations of motion of a system undergoing small oscillations and represents frictional forces which are proportional to velocities; given by a positive definite quadratic form in the time derivatives of the coordinates. Also known as dissipation function.