Abstract
In physical acoustic laboratories, wave propagation experiments often suffer from unwanted reflections at the boundaries of the experimental setup. We propose using multidimensional deconvolution (MDD) to post-process recorded experimental data such that the scattering imprint related to the domain boundary is completely removed and only the Green's functions associated with a scattering object of interest are obtained. The application of the MDD method requires in/out wavefield separation of data recorded along a closed surface surrounding the object of interest, and we propose a decomposition method to separate such data for arbitrary curved surfaces. The MDD results consist of the Green's functions between any pair of points on the closed recording surface, fully sampling the scattered field. We apply the MDD algorithm to post-process laboratory data acquired in a two-dimensional acoustic waveguide to characterize the wavefield scattering related to a rigid steel block while removing the scattering imprint of the domain boundary. The experimental results are validated with synthetic simulations, corroborating that MDD is an effective and general method to obtain the experimentally desired Green's functions for arbitrary inhomogeneous scatterers.
Highlights
Acoustic wave propagation in air or water can be studied physically through laboratory experiments such as in airfilled cavities or water tanks (e.g., Cassereau and Fink, 1992; Fink, 1992)
We focus on post-processing of a dataset acquired in an air-filled waveguide using an multidimensional deconvolution (MDD) method such that the scattering effects of the rigid boundary surrounding the experimental setup are completely removed while only the Green’s functions associated with the scattering object inside the experimental volume are obtained in the absence of an exterior reflecting boundary
Since wavefield separation is key to the proposed change of boundary conditions using MDD, we first demonstrate the performance of the wavefield decomposition method using the multidimensional convolution (MDC) relation given in Eq (5)
Summary
Acoustic wave propagation in air or water can be studied physically through laboratory experiments such as in airfilled cavities or water tanks (e.g., Cassereau and Fink, 1992; Fink, 1992). In practice, low-frequency outward propagating waves are not perfectly absorbed using this approach Another solution is to build an active anechoic chamber where acoustic sources are densely deployed around the boundary of the experimental domain to cancel the outward propagating waves (Beyene and Burdisso, 1997; Guicking and Lorenz, 1984; Habault et al, 2017; Smith et al, 1999). These active sources, sometimes installed together with passive absorbers, can effectively render the boundary transparent for lowfrequency experiments (
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