A computational study of acoustic streaming in a duct

Abstract

The present work is a continuing investigation of Rayleigh streaming, which is a nonlinear phenomenon characterized by acoustically driven flows attenuated by viscous effects due to the presence of walls, resulting in nonzero average streaming velocities and circulation zones within a duct. A 2-D long and narrow duct is considered with one end closed and the other end subject to a sinusoidal acoustic velocity at quarter-wavelength frequencies and varying amplitudes, leading to a standing wave within the duct. A computational fluid dynamics code based on the Pressure Implicit with Split Operators (PISO) algorithm and finite volume method is used to solve the unsteady, compressible Navier–Stokes equations with turbulence modeling. Since the formation of streaming depends on the velocity profile within the Stokes layer, the grid resolution is increased near the walls. The effect of inlet conditions is studied in terms of circulation patterns, including the number of zones per wavelength, penetration depth into the fluid, and mean velocity profiles across the boundary layer. Some of the computational predictions are also compared with the classical analytical treatments.