CFD Online Logo CFD Online URL
Home > Wiki > Mach number

Mach number

From CFD-Wiki

Revision as of 19:07, 30 September 2005 by Ganesh (Talk | contribs)
Jump to: navigation, search

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. To get a more physical insight into Mach number, it is useful if it is viewed as being proportional to the ratio of Kinetic energy to the internal energy of the molecules.

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

My wiki