# Shallow-water models for a vibrating fluid

## TL;DR

This paper derives and analyzes shallow-water models for a vibrating inviscid fluid with a free surface, revealing new dispersive equations that admit solitary and periodic wave solutions, influenced by high-frequency vibrations.

## Contribution

It introduces novel asymptotic shallow-water equations for vibrating fluids, showing their dispersive nature and solution types, extending classical models to include vibration effects.

## Key findings

- Derived three asymptotic models for vibrating fluid surfaces.
- Identified dispersive shallow-water equations with vibration-induced terms.
- Found solitary and periodic wave solutions in the new models.

## Abstract

We consider a layer of an inviscid fluid with free surface which is subject to vertical high-frequency vibrations. We derive three asymptotic systems of equations that describe slowly evolving (in comparison with the vibration frequency) free-surface waves. The first set of equations is obtained without assuming that the waves are long. These equations are as difficult to solve as the exact equations for irrotational water waves in a non-vibrating fluid. The other two models describe long waves. These models are obtained under two different assumptions about the amplitude of the vibration. Surprisingly, the governing equations have exactly the same form in both cases (up to interpretation of some constants). These equations reduce to the standard dispersionless shallow-water equations if the vibration is absent, and the vibration manifests itself via an additional term which makes the equations dispersive and, for small-amplitude waves, is similar to the term that would appear if surface tension were taken into account. We show that our dispersive shallow water equations have both solitary and periodic travelling waves solutions and discuss an analogy between these solutions and travelling capillary-gravity waves in a non-vibrating fluid.