Beaming of inplane elastic waves through a subwavelength channel with periodic corrugations

Abstract

We present an evidence of the beaming phenomenon regarding inplane elastic waves in the context of the enhanced acoustical transmission. Our simulations found emission of a long-range beam through a single subwavelength channel surrounded by periodic structures. The space-time spectral analysis of the inplane displacement field revealed that Rayleigh surface waves principally mediate the energy transmission that leads to the formation of beams. Consequently, we suggest a resonance condition for the beaming in terms of the ratio of the wavelength to the period of the structures. Our findings will be expected to foster the application to ultrasonic devices.

A shape optimisation with the isogeometric boundary element method and adjoint variable method for the three-dimensional Helmholtz equation

“…Interaction of waves with materials in a specific shape/topology can bring exotic wave phenomena such as the extraordinary transmission through a sub-wavelength aperture [1] and the emergence of a collimated beam by corrugating the aperture [2][3][4][5]. In particular, structures with certain periodic patterns, that is, metamaterials have been recently and intensively studied in science and engineering [6,7].…”

Extraordinary acoustic transmission based on source pattern enhancement and reconstruction by metal cylinder structure

“…The first type of EAT structure is composed of a solid plate with periodic sub-wavelength slits and holes, [5][6][7][8][9][10][11][12][13][14][15][16][17] which stems from either the coherent diffraction effect or the Fabry-Perot resonance in the periodic slits and holes. The second type of EAT structure is made up of solid plates with periodical gratings on both sides of a center hole, [18][19][20][21][22][23][24][25] and the surface acoustic waves 26) play an important role in realizing the EAT in this structure. Furthermore, the excitations of the intrinsic Lamb modes in plate structures are also utilized to obtain the EAT.…”