Hidden symmetries, hidden conservation laws and exact solutions of dispersionless Nyzhnyk equation

TL;DR

This paper explores hidden symmetries and conservation laws of the dispersionless Nyzhnyk equation, identifying a special submodel that enables the derivation of new exact solutions and reveals deep algebraic structures.

Contribution

It introduces a unique submodel with rich symmetry properties, providing new exact solutions and insights into the equation's hidden algebraic structures.

Findings

Identified a special submodel with unique symmetry properties.

Constructed new exact solutions using Lie reductions.

Described generalized symmetries and conservation laws.

Abstract

Among Lie submodels of the (real symmetric potential) dispersionless Nyzhnyk equation, we single out a remarkable submodel as such that, despite being the only one, is associated with a family of in general inequivalent one-dimensional subalgebras of the maximal Lie invariance algebra of this equation, which are parameterized by an arbitrary function of the time variable. The large family of invariant solutions of the dispersionless Nyzhnyk equation that are related to the above submodel is expressed in terms of an arbitrary function of the time variable and the double quadrature of the well-known (implicit) general solution of the inviscid Burgers equation with respect to a space-like submodel invariant variable. The singled out submodel possesses many other interesting properties. In particular, we show that it is Lie-remarkable, and its maximal Lie invariance algebra completely defines its point symmetry pseudogroup, which provides the second but simpler example of the latter phenomenon in literature. Moreover, only hidden Lie symmetries of the dispersionless Nyzhnyk equation that are associated with this submodel are essential for finding its exact solutions. Using Lie reductions, we construct new families of exact solutions of the inviscid Burgers equation and the dispersionless Nyzhnyk equation in closed or parametric form. We also exhaustively described generalized symmetries, cosymmetries and conservation laws of the submodel, which gives the corresponding nonlocal and hidden structures for the inviscid Burgers equation and the dispersionless Nyzhnyk equation, respectively.