Interaction of acoustic meta-atoms as additional degrees of freedom for metamaterial tuning

Acoustic metamaterials have a widespread range of application, e.g. acoustic cloaking and acoustic lenses, and usually consist of an arrangement of meta-atoms. These meta-atoms are often based on the principle of local resonances. Herein, we theoretically study the case of two meta-atoms in an unbounded two-dimensional fluid domain in order to analyze their mutual interaction. Furthermore, we vary distance, orientation and detuning while observing the eigenfrequencies of two interacting modes. Certain configurations of the varying parameters mentioned before lead to regions of modal degeneracy, hence to maxima in the transmission loss if excited by a plane wave. Thus, we make use of this phenomenon in order to improve the wave attenuation properties of the meta-atoms..