THE DAMPING OF SOUND BY WALL TURBULENT SHEAR LAYERS

A frequency-dependent model is proposed for the eddy viscosity control ling the momentum and thermal wall boundary layers formed when an acou stic wave interacts with a low Mach number turbulent boundary layer wh ose thickness is much smaller than the acoustic wavelength. This is us ed to determine the effective acoustic admittance df the boundary laye r, and to predict the attenuation of sound reflecting from a plane wal l boundary layer, and low-frequency sound propagating in fully develop ed turbulent pipe flow. The predictions are shown to compare well with a recent experimental study of acoustic attenuation in pipe flows. (C ) 1995 Acoustical Society of America.