Immersive boundary conditions for meta-material experimentation

Abstract

In immersive experimentation, a physical experimentation domain is immersed in a numerical simulation such that waves propagate seamlessly from the physical domain into the numerical simulation and vice-versa. The interaction, governed by a novel immersive boundary condition (IBC), takes place in real-time using hundreds of sources and sensors surrounding the medium connected through a low-latency acquisition, compute and control system. IBCs are currently being realized for acoustic and elastic waves. The ability to impose arbitrary IBCs on an experimentation domain presents unique opportunities for research into novel phononic and parity-time symmetric (PTS) meta-materials. We first show how IBCs can be used to realize phononic materials with arbitrary inclusions by imposing 1-D, 2-D, or 3-D periodic conditions on the boundaries of the experimentation domain. Only one or few unit cells have to be constructed to physically create a complete phononic crystal and reproduce its properties if assumed a component of an infinite periodic lattice. Second, we show how IBCs can be used to implement the gain component of a PTS medium. Since the gain is implemented in the numerical simulation it can be arbitrarily adjusted to exactly balance the experimentally realized loss. Numerical validations and initial experimental results will be presented.