LIE SYMMETRY, NONLOCAL SYMMETRY ANALYSIS, AND INTERACTION OF SOLUTIONS OF A (2+1)-DIMENSIONAL KDV-MKDV EQUATION

摘要

We use the method of Lie symmetry analysis to investigate the properties of a (2+1)-dimensional KdV-mKdV equation. Using the Ibragimov method, which relies only on the existence of the commutator table, we construct an optimal system of one-dimensional subalgebras of the Lie algebra and study invariant solutions and similarity reductions by considering representatives of the optimal system. To analyze some nonlocal symmetry properties, we apply the truncated Painkve expansion method and obtain two Backlund transformations that are not autotransformations and one auto-Backlund transformation. To localize the nonlocal symmetry and obtain a local Lie point symmetry, we introduce an expanded system. Using solutions of the corresponding Cauchy problems for Lie point symmetries, we prove a theorem on a finite symmetry transformation and find the nth Backlund transformation in terms of determinants. Based on one of the obtained Backlund transformations that are not autotransformations, we derive lump-type solutions. In addition, we prove the integrability of the equation by the consistent Riccati expansion method. We present explicit soliton-cnoidal wave solutions and investigate the dynamical characteristics of the obtained solutions using numerical analysis.