Solitons interaction and integrability for a (2+1)-dimensional variable-coefficient Broer Kaup system in water waves

Under investigation in this paper is a (2+1)-dimensional variable-coefficient Broer Kaup system in water waves. Via the symbolic computation, Bell polynomials and Hirota method, the Backlund transformation, Lax pair, bilinear forms, one- and two-soliton solutions are derived. Propagation and interaction for the solitons are illustrated: Amplitudes and shapes of the one soliton keep invariant during the propagation, which implies that the transport of the energy is stable for the (2+1)-dimensional water waves; and inelastic interactions between the two solitons are discussed. Elastic interactions between the two parabolic-, cubic- and periodic-type solitons are displayed, where the solitonic amplitudes and shapes remain unchanged except for certain phase shifts. However, inelastically, amplitudes of the two solitons have a linear superposition after each interaction which is called as a soliton resonance phenomenon.