Reconfigurable spiral underwater sound-absorbing metasurfaces

Abstract A well-designed coiled metasurface can be applied to obtain extraordinary underwater sound isolation. In this letter, we propose a quasi-perfect sound-absorbing metasurface in spiral shape form. This spiral metasurface(SM) meets the two conditions for perfect absorption, which are no transmission at the outlet and no reflection at the inlet. The sound-absorbing characteristics of the SM are investigated through numerical simulation. The simulation results show that the peak frequency of prefect sound absorption can be tuned flexibly over the spectrum, which depends on the design of the parameters. The frequency-controllable SM has quasi-prefect sound absorption coefficient(up to almost 0.998).