Numerical simulations of acoustic metamaterial in grazing flow.

Noise generated by aircraft engines has been a rising cause for concern. The use of acoustic liners for noise attenuation have been extensively studied in the past. In this study, the application of an acoustic metamaterial in a grazing flow impedance tube is explored using a simulation tool to demonstrate its efficacy in the reduction of broadband noise. Numerical simulation of the Navier-Stokes equation is performed using a commercially available multi-physics software, COMSOL. Simulation results indicate that the acoustic metamaterial liners provide a reduction of 5-15 dB in low-frequency broadband noise and thus could serve as candidate materials towards an effective aircraft noise mitigation strategy. A phenomenological theory based on the breakdown of larger eddies into smaller eddies and their eventual decay is also proposed for the observation of such reduction of noise levels. [ABSTRACT FROM AUTHOR]