Asymptotic analysis of acoustic black hole effect in cylindrical shells

The acoustic black hole (ABH) effect is investigated within the framework of thin shell theory. Asymptotic solutions to the dispersion equation for the thin cylindrical shell are obtained, and the ABH effect is examined using analytical formulas for group velocities and anti-derivatives of the asymptotic expansions of wave numbers. It is shown that the ABH effect is achievable in thin cylindrical shells with variable thickness, in a similar manner as for beams and plates. However, it should not be expected to exist in the low-frequency range where the flexural wave motion in the wall of a shell is strongly coupled with uniform longitudinal wave motion.