Volume 79, Number 6, September 2007
Article Number 64002
Number of page(s) 6
Section Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics, and Fluid Dynamics
Published online 28 August 2007
EPL, 79 (2007) 64002
DOI: 10.1209/0295-5075/79/64002

Compressibility effects on the Rayleigh-Taylor instability between miscible fluids

M.-A. Lafay1, B. Le Creurer2 and S. Gauthier1

1  CEA/Bruyères-Le-Châtel - B.P. 12, 91680 Bruyères-Le-Châtel, France
2  CNRS/LIMSI Département Mécanique - B.P. 133, F-91403 Orsay, France (Previous address.)

received 11 April 2007; accepted in final form 26 July 2007; published September 2007
published online 28 August 2007

The linear Rayleigh-Taylor problem for two miscible compressible viscous fluids is solved for the first time. A wide range of parameter values is investigated. Two main parameters govern this instability: the stratification parameter -attached to the hydrostatic equilibrium- and the compressibility parameters -attached to the fluids. For increasing values of the stratification, the flow is stabilized, whereas for increasing values of the compressibility parameters the flow is destabilized. Diffusions (viscosity, thermal conduction and species) introduced a cut-off wave number beyond which the flow is marginally stable. These conclusions usually hold in the nonlinear single-mode regime, except when compressibilities are equal. In this case linear and nonlinear growth rates are in opposite order.

47.20.Ma - Interfacial instabilities (e.g., Rayleigh-Taylor).
47.15.Fe - Stability of laminar flows.
47.11.Kb - Spectral methods.

© Europhysics Letters Association 2007