Redirecting Acoustic Waves Out of the Incident Plane
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This chapter addresses a flat metasurface to manipulate the extraordinary out-of-incident-plane reflection and vibration in acoustics, validated by the theoretical modeling and the numerical experiment. We theoretically demonstrate that in fluids, extraordinarily reflected sound waves can be achieved along a three-dimensional spatial angle out of the incident plane by manipulating the impedance distribution of a flat metasurface reflector. In particular, the arbitrary manipulation can be unanimously predicted and concluded by our three-dimensional impedance-governed generalized Snell’s law of reflection (3D IGSL), which is rigorously derived from Green’s functions and integral equations. Consequently, the vibrations of the extraordinary reflection and the incidence will form a spatial angle in between, rather than sitting in one plane. Such an inhomogeneous flat metasurface can be effectuated by means of impedance discontinuity, and further implemented by tube arrays with properly designed lengths. Finite-element-simulation results agree with the theoretical prediction by 3D IGSL.
KeywordsFluid Particle Incident Plane Flat Interface Helmholtz Resonator Tube Array
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