Analytical Solutions to a Novel Integrable System Based on Painlevé Property and Projective Riccati Equations
摘要
Exact analytical solutions provide mathematically rigorous, unapproximated benchmarks for understanding complex nonlinear wave dynamics. In this paper, we investigate a nonlinear system derived from the compatibility condition of two scalar equations, known as the Zakharov–Ito–Kamchatnov (ZIK) system. Compared to the classical system, which assigns high-order dispersion to the velocity field, the ZIK system uniquely embeds dispersive effects directly within the density evolution equation. This structural shift is of profound physical importance: it accurately models regimes—such as density-stratified fluids and weakly collisional plasmas—where local density fluctuations are stabilized by dispersion rather than merely advected by the flow. A detailed Painlevé analysis is carried out, through which we construct a Bäcklund transformation that establishes a connection between a seed solution and its associated new solutions. The Painlevé analysis not only verifies the integrability of the ZIK system but also lays a solid theoretical foundation for the derivation of the Bäcklund transformation. Methodologically, once the coupled ZIK system passes the Painlevé test and is reduced to a first-order form, the projective Riccati method can be directly applied. By employing this approach, we construct various types of exact analytical solutions. These solutions include typical forms like solitary wave and periodic wave solutions, which are crucial for interpreting the practical physical behaviors modeled by the ZIK system. In addition, three-dimensional profiles plots of these solutions are presented using Maple to illustrate their dynamic characteristics.