The propagation of wave, packets on, the surface of an electrically conducting fluid of uniform depth in, the ...presence of a tangential magnetic 'fieJd is investigated in (2 + 1) dimensions. The evolution of,wave envelope is governed by two coupled partial differential equations with cubic nonlinearity. The atability analysis reveals the existence of different regions of instability. The effect of the applied magnetic field is not only significant but also different for different regions of stability. 'Envelope soliton' and 'waveguide' solutions of the amplitude equation are also discussed. The self-focusing phenomenon that arises when the amplitude of the wave becomes infinite in finite time is also examined. It is found that in a certain region of the atability diagram.it may be easier to observe this phenomenon in the presence of a magnetic field. The Rayleigh-Taylor. problem is also studied and various criteria for the existence of instability are obtained.
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