Immersive experimentation: A new paradigm for low-frequency acoustic and elastic wave propagation experimentation

Abstract

Immersive experimentation is a new paradigm for wave-based laboratory experimentation aimed at overcoming the laboratory- and sample-size related limitations of conventional approaches and thereby significantly extending downwards the usable frequency range. Using so-called immersive boundary conditions, a physical experimentation domain or elastic rock volume can be immersed in an arbitrary larger numerical domain in such a way that the waves in the physical domain drive the simulation in the numerical domain and vice-versa. Waves propagating towards the edges of the experimentation domain are sensed by dense receiver arrays and extrapolated to/ decomposed at the boundary where they are actively suppressed. Waves incident on the boundary are also extrapolated through the larger numerical domain using pre-computed Green’s functions and re-emitted into the experimentation domain, enabling arbitrary order scattering interactions between the laboratory or sample and the numerical domain. We present two laboratories currently under construction at ETH Zurich: WaveLab, an acoustic lab, which implements immersive experimentation in real-time using a low-latency, high-performance acquisition, compute and control system and matrix, an elastic experiment, which implements immersive experimentation using a robotized three-component scanning LDV and novel methods for wavefield separation and injection at an elastic free surface. Implementation, results, and applications are discussed.