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Issue
EPL
Volume 86, Number 1, April 2009
Article Number 15002
Number of page(s) 6
Section Physics of Gases, Plasmas and Electric Discharges
DOI http://dx.doi.org/10.1209/0295-5075/86/15002
Published online 15 April 2009
EPL, 86 (2009) 15002
DOI: 10.1209/0295-5075/86/15002

Weakly nonlinear analysis on the Kelvin-Helmholtz instability

L. F. Wang1, 2, W. H. Ye3, 4, 1, Z. F. Fan1, Y. J. Li2, X. T. He1, 3, 4 and M. Y. Yu5

1   Laboratory of Computational Physics, Institute of Applied Physics and Computational Mathematics Beijing 100088, China
2   School of Mechanics and Civil Engineering, China University of Mining and Technology Beijing 100083, China
3   Department of Physics, Zhejiang University - Hangzhou 310027, China
4   Center for Applied Physics and Technology, Peking University - Beijing 100871, China
5   Institute for Fusion Theory and Simulation, Zhejiang University - Hangzhou 310027, China

ye_wenhua@iapcm.ac.cn

received 7 February 2009; accepted in final form 16 March 2009; published April 2009
published online 15 April 2009

Abstract
A weakly nonlinear model is proposed for the Kelvin-Helmholtz instability in two-dimensional incompressible fluids. The second- and third-harmonic generation effects of single-mode perturbation, as well as the nonlinear correction to the exponential growth of the fundamental modulation are analyzed. An important resonance in the mode-coupling process is found. The nonlinear saturation time depends on the initial perturbation amplitude and the density ratio of the two fluids, but the nonlinear saturation amplitude depends only on the initial perturbation amplitude. The weakly nonlinear result is supported by numerical simulation. The practical system of boundary layer containing thermal conductivity is analyzed. Their nonlinear saturation amplitude can be predicted by our weakly nonlinear model.

PACS
52.35.Py - Macroinstabilities (hydromagnetic, e.g., kink, fire-hose, mirror, balloning, tearing, trapped-particle, flute, Rayleigh-Taylor, etc.).
52.57.Fg - Implosion symmetry and hydrodynamic instability (Rayleigh-Taylor, Richtmyer-Meshkov, imprint, etc.).
47.20.Ft - Instability of shear flows (e.g., Kelvin-Helmholtz).

© EPLA 2009