A numerical investigation of the effects of a transverse temperature gradient on the formation of regular and irregular acoustic streaming in an enclosure

Abstract

The effects of a transverse temperature gradient on the formation of regular and irregular acoustic streaming structures in air-filled, two-dimensional, rectangular, shallow enclosures carrying a longitudinal sound field are investigated numerically. The fluid motion is induced by the harmonic vibration of the enclosure left wall. The fully compressible form of the Navier-Stokes equations is considered to predict the primary oscillatory and secondary pseudo-steady streaming flow fields. An explicit time-marching flux-corrected transport algorithm is used to simulate the acoustic wave formation, propagation, and the resulting flow patterns in the enclosure. The vertical walls of the enclosure are adiabatic whereas the horizontal walls are heated differentially or symmetrically. The transverse temperature gradients are found to strongly affect the acoustic streaming structures and the velocities. The steady streaming velocities significantly increase when the enclosure horizontal walls are asymmetrically heated for both regular and irregular streaming flows. For irregular streaming, the transverse temperature gradients completely change the flow patterns. The irregular streaming velocities are greatly reduced in case of the symmetric temperature increase of the horizontal walls.