The influence of schlichting vortices on the absorption of sound by a solid surface

Abstract

The aim of this work is to study the mechanisms of acoustic energy dissipation due to the physical processes occurring in the acoustic boundary layer (APS), which occurs when the standing sound wave interacts with a solid surface. Unlike laminar APS in this case, in the wall layer of the medium, in addition to inhomogeneous viscous and thermal waves, acoustic Schlichting flows occur. Vortices can exist only due to the energy taken from the standing sound wave in consequence of which an additional mechanism of energy dissipation appears in the APS. A cylindrical tube with rigid walls, the ends of which are closed by impedance lids, was chosen as the object of research. When the longitudinal half-wave resonances are excited in the pipe, standing waves are excited in the pipe, formed due to the interaction of the normal zero-order sound waves running towards each other