On Alternative Model of Sound Scattering in Turbulent Moving Media

Abstract

Model of sound scattering in turbulent mediu m co mprising chaotically distributed in space moving in manifold directions spherically symmet ric structures-localized flo ws, say, vortices of various linear dimensions from s mallest "Kolmogorov's" to outer turbulent scales is proposed. Scattering crossections and distance attenuation parameters related to structures motion in the presence and absence of vorticity inside them for sound waves are calculated on etalon problem solutions basis. Resulting frequency dependencies and scattering laws in model med iu m differ substantially not only fro m Rayleigh law but fro m several other well known predicted patterns of sound scattering in turbulent mediu m as well. Attenuation value is expected to depend on vortices Mach number to scattering wave parameter ratio. Model parameter control is available by means of dimensions, velocities and concentration of basic localized flo w changes corresponding to turbulence scale, intensity and degree of development changes. Co mparison of expected attenuation parameters with experimental data and estimates based on classical isotropic turbulence models is presented.

Wind tunnel investigation of sound attenuation in turbulent flow

“…Earlier experimental studies revealed that in the case of the short-range propagation the sound attenuation irregularities in the wind structure exceeded substantially classical absorption (through shear viscosity, heat conduction and radiation, diffusion) and molecular absorption (both that due to oxygen and nitrogen) [4]. Detailed review of experimental works related to so-called excess attenuation (beyond that due to classical and molecular absorption) presented in [21]. It has been established that sound was more influenced by wind fluctuations than by temperature fluctuations [18], Cheinet et al [5].…”

“…Many approaches have been used to simulate the propagation of acoustic waves through random media [21] and references therein.…”