Микроволновый семинар. Миронов

Prof. Mikhail Mironov (Andreyev Acoustics Institute, Russia)

'Acoustic / vibrational black holes'

Abstract: The theoretical question of wave theory, which, as a result, gave rise to the line of A/VBH inquiry (search in Internet Acoustic Black Holes (ABH)), is as follows. Is it possible to slow down the wave propagation velocity on a segment of finite length so that the propagation time on this segment is infinite? The slowing should not be too sharp, so that there are no reflections from the intermediate sections. The answer is - Yes. The implementation of this deceleration allows, at least theoretically, absorbing waves without the use of absorbing material. The wave which has come into BH, will not reach its end for any finite time and, therefore, will not be reflected. Designs that implement the BH effect are: for sound - comb structure in an acoustic waveguide – the deeper the groove, the lower the velocity propagation of the normal wave. For vibration one - smoothly sharpened rod (plate). The thinner is the rod, the lower is the phase and group propagation velocities. The report describes the history of development of this, today popular, direction, presents equations, asymptotic and exact solutions for specific designs of acoustic and vibrational BH, gives the results of experiments and discusses possible lines of investigations and applications.