Analogue White Hole Horizon and its Impact on Sediment Transport

TL;DR

This study explores analogue white hole horizons in a water flume, demonstrating wave blocking phenomena and their effects on sediment transport, including novel findings without obstacles and with movable beds.

Contribution

It introduces the first observation of wave blocking without obstacles and examines sediment transport effects caused by the wave blocking zone.

Findings

Wave blocking occurs at a critical wave frequency.

Wave blocking influences sediment ripple patterns.

Wave blocking persists without obstacles, creating diffused zones.

Abstract

Motivated by the ideas of analogue gravity, we have performed experiments in a flume where an analogue White Hole horizon is generated, in the form of a wave blocking region, by suitably tuned uniform fluid (water) flow and counter-propagating shallow water waves. We corroborate earlier experimental observations by finding a critical wave frequency for a particular discharge above which the waves are effectively blocked beyond the horizon. An obstacle, in the form of a bottom wave, is introduced to generate a sharp blocking zone. All previous researchers used this obstacle. A novel part of our experiment is where we do not introduce the obstacle and find that wave blocking still takes place, albeit in a more diffused zone. Lastly we replace the fixed bottom wave obstacle by a movable sand bed to study the sediment transport and the impact of the horizon or wave blocking phenomenon on the sediment profile. We find signatures of the wave blocking zone in the ripple pattern.