Trapping and absorption of sound waves I a screened sphere
Journal
Wave Motion
Journal Volume
12
Journal Issue
1
Pages
1-13
Date Issued
1990
Author(s)
Abstract
Linear acoustic waves associated with a sphere covered by a concentric porous screen are studied. The effects of a porous screen on the radiation of sound generated by the surface vibration of a sphere, as well as the scattering of an incident plane wave by a stationary sphere, are analyzed based on the method of separation of variables. The acoustic power far away from a screened sphere is compared to that associated with a sphere without a screen. The present results indicate that, as the ratio of the sphere radius to the wavelength, rb/λ, increases, the relative acoustic power becomes a periodic function with respect to the gap-to-wavelength ratio d/λ, white the amplitude is dependent on the screen Reynolds number Re. The optimum gap distance, which minimizes the relative acoustic power, is found to be a quarter wavelength plus a multiple of the half-wavelength. As the radius-to-wavelength ratio rb/λ tends to infinity, the optimum screen Reynolds number, which minimizes the relative acoustic power, is 1.0 for the scattering of a plane incident wave. © 1990.
Type
journal article