DC carpet cloak designed by topology optimization based on covariance matrix adaptation evolution strategy.

Optimal designs of direct current (DC) carpet cloaks are obtained using topology optimization based on the covariance matrix adaptation evolution strategy. The cloaking structures are expressed using an immersed boundary-level set method visualized as gray-scale-free configurations and composed simply of homogeneous materials. These cloaks successfully hide bumps made electrically invisible through topology optimization by minimizing the difference in voltage distributions around the cloaked bump and over the flat surface in the absence of the bump. Moreover, reproducing the electric potential field without a bump for DC flowing over a wide angle is achieved by the optimal cloak despite the presence of the bump on the flat surface.