Layered elliptical-cylindrical acoustic cloaking design based on isotropic materials

A layered co-focal elliptical-cylindrical acoustic cloak is designed based on the effective medium theory. The distribution of acoustic field is simulated using the finite element method. The cloak possesses the properties of low-reflection outside and wavefront-bending in the cloak shell. The relationship between the cloaking effect and the number of discrete layers, the direction of incident wave are also investigated. The effective working frequency band can be broadened by using more layers. As the cloak is of a line-transformed type, its properties are associated with the direction of incident wave. Only when the incident wave is parallel to the major axis of the ellipse, can the cloak have the best performance. In addition, the cloak is of a cylindrical structure as the focus of the ellipse-cylinder is small enough. This work is expected to be helpful for realizing acoustic cloaks with complex shapes.