Acoustic ground cloaks revisited

The unique material properties now obtainable with acoustic metamaterials have led to unprecedented control of acoustic wave propagation, resulting in many applications including acoustic cloaking. The two fundamental approaches in the development of a ground cloak are quasiconformal mapping [Li et al. Phys. Rev. Lett. 101, 203901 (2008)] and coordinate transformations [Popa et al. Phys. Rev. B. 83, 224304 (2011)]. The differences in the required material properties prescribed by these two approaches lie in the amount of anisotropy and inhomogeneity, as well as the size of the cloak relative to object. The coordinate transformation approach has been used to produce a realizable anisotropic homogeneous ground cloak in the acoustic domain. This presentation will highlight the findings of work that examined how advances in metamaterial development could lead to the realization of required material properties for ground cloaks, and explore alternative transformations to expand the applications for acoustic ground cloaks.