Forced convective heat transfer by turbulent baroclinic acoustic streaming

Unusually strong acoustic streaming flows can be generated in gases subjected to an imposed cross-channel temperature gradient. In contrast with classic Rayleigh streaming, standing sound waves acquire vorticity owing to baroclinic torques acting throughout the domain rather than via viscous torques acting in Stokes boundary layers [Chini et al., J. Fluid Mech., Vol. 744 (2014); Michel & Chini, J. Fluid Mech., Vol. 858 (2019)]. Consequently, these baroclinically-driven streaming flows have an amplitude comparable to that of the acoustic waves, leading to fully two-way wave/mean-flow coupling. The present investigation extends our earlier studies by accessing a parameter regime in which the streaming flow is spatiotemporally chaotic. Although the flow is acoustically-driven and buoyancy forces are not included, the time-dependent streaming temperature field resembles that arising in turbulent Rayleigh--B\'{e}nard convection. The velocity field differs, however, being strongly confined to the periphery of the unsteady convection cells. We elucidate the physical origin of this flow pattern and quantify the forced convective heat transport accomplished by the turbulent baroclinic acoustic streaming.