Search

Abstract: The effects of classical and irregular streaming motion on convective heat transfer in air-filled shallow enclosures carrying a standing sound wave are investigated. The fluid motion is driven by the periodic vibration of the enclosure left wall. The vertical walls of the enclosure are adiabatic while the horizontal walls are heated differentially. The fully compressible form of the Navier–Stokes equations are considered to compute the oscillatory and mean flow fields. A control-volume method based, explicit time-marching Flux-Corrected Transport (FCT) Algorithm is used to simulate the transport phenomena in the enclosure. The simulation results of a test case for an unheated enclosure are compared with the existing literature for code validation. Transverse temperature gradient strongly affects the acoustic streaming structures and velocities. The streaming motion significantly enhances overall heat transfer from the bottom wall compared to pure conduction. Enhancement is more pronounced in the presence of irregular streaming. [ABSTRACT FROM AUTHOR]

Thermal convection in a differentially heated shallow enclosure due to acoustic excitations induced by the vibration of a vertical side wall is investigated numerically. The fully compressible form of the Navier-Stokes equations is considered and an explicit time-marching algorithm is used to track the acoustic waves. Numerical solutions are obtained by employing a highly accurate flux corrected transport algorithm. The frequency of the wall vibration is chosen such that an acoustic standing wave forms in the enclosure. The interaction of the acoustic standing waves and the fluid properties trigger steady secondary streaming flows in the enclosure. Simulations were also carried out for "off-design" vibration frequency where no standing waves were formed. The effects of steady second order acoustic streaming structures are found to be more significant than the main oscillatory flow field on the heat transfer rates. The model developed can be used for the analysis of flow and temperature fields driven by acoustic transducers and in the design of high performance resonators for acoustic compressors. [ABSTRACT FROM AUTHOR]

The influence of hydrodynamically developing nonzero mean acoustic streaming motion on transient convective heat transfer in an air-filled rectangular enclosure is studied numerically. The enclosure is two-dimensional with sinusoidal bottom wall spatial temperature distribution. The oscillatory flow under relatively large Womersley number regime conditions is actuated by the periodic vibrations of the enclosure side wall. The side walls of the enclosure are adiabatic, while the top wall is isothermal. The compressible form of the Navier--Stokes equations is considered to predict the oscillatory- and time-averaged mean flow fields. A control-volume method based explicit computational scheme is used to simulate the convective transport in the enclosure. The longitudinal and the transverse temperature gradients strongly affect the flow structure in the enclosure. The mean fluid motion alters the heat transfer behavior compared to the pure conduction. [ABSTRACT FROM AUTHOR]