Active acoustic cloaking in a convected flow field.

Acoustic cloaking has mostly been considered within a stationary fluid. The authors herein show that accounting for the effects of convection in the presence of fluid flow is critical for cloaking in the acoustic domain. This work presents active acoustic cloaking in a convected flow field for two different incident fields, corresponding to a plane wave and a single monopole source, impinging on a rigid body. Monopole control sources circumferentially arranged around the rigid body are used to generate a secondary acoustic field to destructively interfere with the primary scattered field arising from the incident excitation cases. The authors show that for sound waves in a moving fluid, active cloaking can only be achieved using a convected cloak, which is dependent on Mach number.