Acoustic Cloning and surface-based Digital Twins

Acoustic Cloning enables cloning the complete acoustic scattering behavior of unknown objects in a two-step process: in the first step, an object is insonified for a range of angles using temporally broadband sources while the response is recorded on a circular aperture enclosing the object. The scattering Green’s functions (GFs) of the object are retrieved from the recorded responses by multi-dimensional deconvolution. In the second step, the object is removed and reproduced holographically for arbitrary, previously unseen, broadband incident wavefields. At the heart of each acoustic clone are the scattering GFs of the object for radiation conditions. In the reproduction step, these scattering GFs enable real-time extrapolation of arbitrary incident wavefields by acting as the kernel of a Kirchhoff–Helmholtz (KH) integral. Extrapolated to a set of monopole and dipole sources, the GFs allow reproducing the scattered wavefield without the object being present. These scattering GFs can thus be regarded as a surface-based Digital Twin (SBDT) of the scattering object. We present examples of real, experimentally acquired SBDTs and show that they can be probed both numerically and experimentally. The SBDTs open new avenues for inclusion and manipulation of complex real acoustic scatterers in real or numerical scattering environments.