Supershear Rayleigh waves at a soft interface

TL;DR

This study experimentally demonstrates the existence of supershear Rayleigh waves on a liquid foam surface, which propagate faster than bulk shear waves, providing new insights into wave behavior at soft interfaces.

Contribution

The paper provides the first experimental observation of supershear Rayleigh waves on a soft, viscoelastic interface using an optimized profilometry technique.

Findings

Supershear Rayleigh waves propagate faster than bulk shear waves.

High impact velocity triggers supershear surface waves.

Surface waves are observed on a liquid foam surface.

Abstract

We report on the experimental observation of waves at a liquid foam surface propagating faster than the bulk shear waves. The existence of such waves has long been debated, but the recent observation of supershear events in a geophysical context has inspired us to search for their existence in a model viscoelastic system. An optimized fast profilometry technique allowed us to observe on a liquid foam surface the waves triggered by the impact of a projectile. At high impact velocity, we show that the expected subshear Rayleigh waves are accompanied by faster surface waves that can be identified as supershear Rayleigh waves.