On the reflection of time-domain acoustic spherical waves by a sinusoidal diffraction grating

Guochao Gao,Carole Deumié,Paul Cristini,Nathalie Favretto-Cristini

doi:10.1051/aacus/2020033

Abstract

This work reports on some results obtained from numerical simulations of time-domain acoustic wave propagation in the presence of a periodically rough interface. Emphasis is put on the structure of the reflected signals in the presence of a sinusoidal grating. More specifically, we investigate the effect of the frequency bandwidth of the emitted signal and the effect of the incident wavefront sphericity on the signals reflected from the rough interface and associated with the different diffraction orders.

Highlights

The main objective that underlies the work presented here is to better understand the impact of rough interfaces in seismic wave propagation and in seismic imaging, in order to possibly better handle rough interfaces
Despite elastic effects play an important role in the real geophysical world, we consider here a very simplified case, namely acoustic waves interacting with sinusoidal interfaces, in order to better understand the effect of roughness characteristics on the spherical wavefronts in the time domain
In the case of an incident non-monochromatic acoustic wave, that carries naturally several wavelengths, the angle hn associated with a given diffraction order n is no more unique but lies within a broad range provided by the grating equation

Summary

Introduction

The main objective that underlies the work presented here is to better understand the impact of rough interfaces in seismic wave propagation and in seismic imaging, in order to possibly better handle rough interfaces. In the case of an incident non-monochromatic acoustic wave, that carries naturally several wavelengths, the angle hn associated with a given diffraction order n is no more unique but lies within a broad range provided by the grating equation. The analysis relies on 2D numerical simulations conducted in the time domain

Configurations and numerical modelling

Time-frequency analysis of the numerical results

Conclusion