Bandgap characteristics of phononic crystal by considering fluid convection

Abstract

In this study, we investigate the bandgap of phononic crystals by considering fluid convection. As reported in a previous study, it was experimentally shown that the attenuation strength of bandgap of phononic crystal decreased due to flow effects. To analyze the effect of flow on the bandgap performance, we calculate the acoustic reflectance of phononic crystal depend-ing on the different types of background flow such as uniform flow, non-uniform steady flow, and turbulent flow by using numerical computation. In case of the uniform flow and the non-uniform steady flow, the reflectance curves shift to the low frequency region as the flow speed increases mainly due to the Doppler effect. In case of turbulent flow, bandgap performance decreases with increasing flow speed due to the aerodynamic noise caused by flow passing through the phononic crystal. This study provides a theoretical basis for designing phononic crystals to maintain the bandgap performance in flow fields.