Trapped modes in a non-axisymmetric cylindrical waveguide

摘要

We consider acoustic wave transmission in a non-axisymmetric waveguide which consists of a cylindrical resonator and two cylindrical waveguides whose axes are shifted relatively to each other by an azimuthal angle Delta phi Under variation of the resonator's length L and fixed Delta phi we find bound states in the continuum (trapped modes) due to full destructive interference of resonant modes leaking into the wave guides. Rotation of the waveguide adds complex phases to the coupling strengths of the resonator eigenmodes with the propagating modes of the waveguides tuning Fano resonances to give rise to a wave faucet. Under variation of Delta phi with fixed resonator's length we find symmetry protected trapped modes. For Delta phi not equal 0 these trapped modes contribute to the scattering function supporting high vortical acoustic intensity spinning inside the resonator. The waveguide rotation brings an important feature to the scattering and provides an instrument for control of acoustic transmittance and wave trapping. (C) 2018 Elsevier Ltd. All rights reserved.