Interacting waves of Davey-Stewartson III system

Modulational unstable regions of the Davey-Stewartson (DS) III system have been determined from the generalized dispersion relation associating the frequency and wavenumber of the modulating perturbations. By means of the multilinear variable separation approach, the variable separation solution for the DS III equation is obtained with two arbitrary functions of (x,t) and two arbitrary functions of (y,t), which can be utilized to generate various (2+1)-dimensional localized excitations. Particular attention is paid on the interacting waves between periodic multivalued foldons and single-valued dromions, which can be viewed as periodic extensions of single foldon-dromion excitations.