Excised acoustic black holes: the scattering problem in the time domain

TL;DR

This paper numerically investigates acoustic black holes using time-domain simulations, revealing superradiant scattering and energy extraction, and demonstrating the applicability of gravitational wave analysis tools to acoustic analogs.

Contribution

It introduces a numerical approach to study acoustic black hole scattering, applying advanced mathematical tools from gravitational physics to acoustic systems.

Findings

Superradiant scattering can significantly amplify acoustic signals.

Energy extraction from acoustic black holes is feasible at specific frequencies.

Time-domain simulations effectively model complex scattering phenomena.

Abstract

The scattering process of a dynamic perturbation impinging on a draining-tub model of an acoustic black hole is numerically solved in the time domain. Analogies with real black holes of General Relativity are explored by using recently developed mathematical tools involving finite elements methods, excision techniques, and constrained evolution schemes for strongly hyperbolic systems. In particular it is shown that superradiant scattering of a quasi-monochromatic wavepacket can produce strong amplification of the signal, offering the possibility of a significant extraction of rotational energy at suitable values of the angular frequency of the vortex and of the central frequency of the wavepacket. The results show that theoretical tools recently developed for gravitational waves can be brought to fruition in the study of other problems in which strong anisotropies are present.