STREAMING FLOWS DUE TO G-JITTER-INDUCED NATURAL-CONVECTION

We investigate streaming in a square cavity where a lateral temperatur e gradient interacts with a constant gravity field modulated by small harmonic oscillations of order epsilon. The Boussinesq equations are e xpanded by regular perturbation in powers of epsilon, and the O(epsilo n2) equations contain Reynolds-stress-type terms that cause streaming. The resulting hierarchy of equations is solved by finite differences to investigate the O(epsilon1) and O(epsilon2) fields and their parame tric dependence on the Rayleigh number Ra, Prandt] number Pr, and forc ing frequency omega. It has been found that the streaming flow is quit e small at small values of Ra, but becomes appreciable at high Ra and starts to influence such flow properties as the strength of the circul ation and the overall heat transfer. Under suitable parametric conditi ons of finite frequency and moderate Pr the periodic forcing motion in teracts with the instabilities associated with the O(epsilon0) base fl ow leading to resonances that become stronger as Ra increases. It is a rgued that these resonances will have their greatest effect on streami ng for Pr almost-equal-to 1. At low frequencies the streaming flow sho ws marked structural changes as Ra is increased leading to an interest ing change in the sign of the O(epsilon2) contribution to the Nusselt number. Also, as the frequency is changed the O(epsilon2) Nusselt numb er again changes sign at approximately the resonant frequency.