Dispersive shock waves and modulation theory

TL;DR

This paper reviews fifty years of mathematical and physical research on dispersive hydrodynamics, focusing on dispersive shock waves, their properties, and applications across various physical systems using Whitham's averaging theory.

Contribution

It provides a comprehensive survey of dispersive hydrodynamics, emphasizing the development of DSW theory, including a non-integrable DSW fitting method and recent advances in complex environments.

Findings

Analysis of macroscopic and microscopic DSW properties

Development of a DSW fitting procedure independent of integrability

Application of DSW theory to multiple physical systems

Abstract

There is growing physical and mathematical interest in the hydrodynamics of dissipationless/dispersive media. Since G.~B.~Whitham's seminal publication fifty years ago that ushered in the mathematical study of dispersive hydrodynamics, there has been a significant body of work in this area. However, there has been no comprehensive survey of the field of dispersive hydrodynamics. Utilizing Whitham's averaging theory as the primary mathematical tool, we review the rich mathematical developments over the past fifty years with an emphasis on physical applications. The fundamental, large scale, coherent excitation in dispersive hydrodynamic systems is an expanding, oscillatory dispersive shock wave or DSW. Both the macroscopic and microscopic properties of DSWs are analyzed in detail within the context of the universal, integrable, and foundational models for uni-directional (Korteweg-de Vries equation) and bi-directional (Nonlinear Schr\"{o}dinger equation) dispersive hydrodynamics. A DSW fitting procedure that does not rely upon integrable structure yet reveals important macroscopic DSW properties is described. DSW theory is then applied to a number of physical applications: superfluids, nonlinear optics, geophysics, and fluid dynamics. Finally, we survey some of the more recent developments including non-classical DSWs, DSW interactions, DSWs in perturbed and inhomogeneous environments, and two-dimensional, oblique DSWs.