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Streaming flows due to g-jitter-induced natural convection

Published online by Cambridge University Press:  26 April 2006

A. Farooq
Affiliation:
Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA
G. M. Homsy
Affiliation:
Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA

Abstract

We investigate streaming in a square cavity where a lateral temperature gradient interacts with a constant gravity field modulated by small harmonic oscillations of order ε. The Boussinesq equations are expanded by regular perturbation in powers of ε, and the O2) equations contain Reynolds-stress-type terms that cause streaming. The resulting hierarchy of equations is solved by finite differences to investigate the O1) and O2) fields and their parametric dependence on the Rayleigh number Ra, Prandtl number Pr, and forcing frequency ω. It has been found that the streaming flow is quite small at small values of Ra, but becomes appreciable at high Ra and starts to influence such flow properties as the strength of the circulation and the overall heat transfer. Under suitable parametric conditions of finite frequency and moderate Pr the periodic forcing motion interacts with the instabilities associated with the Oo) base flow leading to resonances that become stronger as Ra increases. It is argued that these resonances will have their greatest effect on streaming for Pr ≈ 1. At low frequencies the streaming flow shows marked structural changes as Ra is increased leading to an interesting change in the sign of the O2) contribution to the Nusselt number. Also, as the frequency is changed the O2) Nusselt number again changes sign at approximately the resonant frequency.

Type
Research Article
Copyright
© 1994 Cambridge University Press

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