Design of radial sonic crystal for sound attenuation from divergent sound source

• Design of periodic structure for divergent acoustic wave based on computational modeling of governing differential equation.
• The design is tested by finite element simulation and experiment.
• The developed sonic crystal resembles as a fish-bone structure.
• The design is further improved by using elliptic scatterers.

Sonic crystals are periodic arrangement of sound hard scatterers, generally in square or triangular lattice configuration. The periodic obstruction to the sound wave by the scatterers leads to an interesting phenomenon of the band gap, which results in a high sound attenuation in the band gap region. In this work, a design of sonic crystal called as the radial sonic crystal is presented, which consists of periodic structures in polar coordinates. Such a structure attenuates divergent sound source. The radial sonic crystal is designed based on the Webster horn equation and using the property of invariance of governing equation from one unit cell to another. The designed radial sonic crystal is tested experimentally and by the finite element simulation. The experimental results are in good agreement with the simulation and show high sound attenuation of 30 dB. The high sound attenuation is due to the presence of the band gap in the radial sonic crystal.