# Mach number

From Encyclopedia of Mathematics

One of the basic criteria of aerodynamic similarity when the viscosity of the gas cannot be neglected. Mach's number $M=v/a$ is the ratio of the velocity of the gas flow and the velocity of sound at the same point of the flow (or the ratio of the velocity of a body in the gas and the velocity of sound in this medium). The number was called thus to honour E. Mach.

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#### References

[a1] | L. Howarth (ed.) , Modern development in fluid dynamics. High speed flow , 1–2 , Oxford Univ. Press (1953) |

**How to Cite This Entry:**

Mach number.

*Encyclopedia of Mathematics.*URL: http://www.encyclopediaofmath.org/index.php?title=Mach_number&oldid=32439

This article was adapted from an original article by BSE-3 (originator), which appeared in Encyclopedia of Mathematics - ISBN 1402006098. See original article