Mach number

Revision as of 10:31, 13 September 2005 by Jola (Talk | contribs)

The Mach number, $M$ , is the local flow-speed, $u$ , divided by the local speed of sound, $a$ :

$M \equiv \frac{u}{a} \equiv \frac{\mbox{local flow speed}}{\mbox{local speed of sound}}$

The Mach number can be used to categorise compressible flows into different Mach number regimes

The name "Mach number" originates from the famous pioneer in compressible fluid dynamics Ernst Mach