Séminaire

Titre :	Kim Pham (ENSTA Paris) - Scattering of acoustic waves in water through a resonant bubbly screen
Contact :	Pierre Amenoagbadji
Date :	30/11/2023
Lieu :	ENSTA Paris, Amphi 2.3.29

This study concerns the propagation of acoustic waves in water through a thin screen made of a two-dimensional periodic arrangement of air bubbles of arbitrary shapes. The bubbles are subwavelength oscillators of the Minnaert type whose resonant character emerges from the high contrast in density properties between water and air. An asymptotic analysis is carried out to determine the effective behavior of the bubbly screen in the subwavelength regime. This is based on a three-scales homogenization framework involving the scale of a bubble, that of the array and eventually that of the incident wavelength. The resulting effective model is set in the water (the screen has disappeared) and it encapsulates the effect of the resonant screen in a jump of the normal acoustic velocity coupled with an harmonic oscillator equation involving the Minnaert frequency. The performances of the effective model is validated by comparisons with direct numerical simulations.