Atwood number

From Wikipedia, the free encyclopedia

The Atwood number is a dimensionless number in fluid dynamics used in the study of hydrodynamic instabilities in density stratified flows. It is a dimensionless density ratio defined as

$A = \frac{\rho_1 - \rho_2} {\rho_1 + \rho_2}$

where

ρ 1

= density of heavier fluid

ρ 2

= density of lighter fluid

[edit] Field of application

Atwood number is an important parameter in the study of Rayleigh–Taylor instability and Richtmyer-Meshkov instability. In Rayleigh–Taylor instability, the penetration distance of heavy fluid bubbles into the light fluid is a function of acceleration time scale, $A g t 2$ ^[1] where g is the gravitational acceleration and t is the time.

[edit] References

^ Glimm, J., Grove, J. W., Li, X.-L., Oh, W., and Sharp, D. H., A critical analysis of Rayleigh–Taylor growth rates, J. Comput. Phys., 169, 652-677 (2001).