Cauchy number
From Glossary of Meteorology
(Also Hooke number.) In fluid mechanics, a dimensionless group that arises in the study of compressible flow.
The square of the Mach number, its physical interpretation is the ratio of inertia force (ρU2) to compressibility force (1/κ), where ρ is density, U is a characteristic speed, and κ is compressibility.
