Superradiance in acoustic black hole

Abstract: Rotating superradiance in cylinders has recently been observed experimentally using acoustic waves to shed light on the understanding of the superradiant phenomenon in black holes. In this paper, for the first time, we study superradiance in acoustic black holes through theoretical analysis and numerical simulation using COMSOL multiphysics. We find that superradiance can occur in acoustic black holes when the general superradiance condition is met. We also find the amplification effect is significantly weaker in acoustic black holes than in regular cylinders, due to the absorption in such structure.