^{1}Department of Mathematics,Indian Institute of Engineering Science and Technology, P. O. Botanical Garden, Howrah - 711103, West Bengal, India;

^{2}Department of Mathematics,IIEST, Howrah - 711103, West Bengal, India.

Abstract

Asymptotically exact and nonlocal fourth order nonlinear evolution equations are derived for two coupled fourth order nonlinear evolution equations have been derived in deep water for two capillary-gravity wave packets propagating in the same direction in the presence of wind flowing over water.We have used a general method, based on Zakharov integral equation.On the basis of these evolution equations,the stability analysis is made for a uniform capillary gravity wave train in the presence of another wave train having the same group velocity. Instability condition is obtained and graphs are plotted for maximum growth rate of instability and for wave number at marginal stability against wave steepness for some different values of dimensionless wind velocity.

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