Oscillatory Phenomena of Low-Prandtl-Number Fluids in a Rectangular Cavity

Abstract

The osci/lalory phenomena in natural conaeaion of low-Prandtl-number fluids were studied numerically in a rectangular cavily with horizontal temperature gradient at Prandtl number Pr = 0.01, aspect ratio A = I, 2, or 4, and Raykigh number Ra = 10', to', or 10'. In the case ofA = IamainstrongroundrollcellwasformedatRa = 10'. Howevtr,atRa = lOs and 10', two secondary roll cells in the core of a main roll cell were formed and rolllled around the center of the system. The flow was oscillating. In the case of A = 2, i.e.; a taller regime, the shape of the main roll cell varied with time at and above Ra = 10', and then the secondary complicated weak roll cells were formed above and below the main roll cell.This resulted in osci/lalory phenomena even at Ra = /0'. In the case of A = 4, three main roll cells were formed. AI Ra = to', secondary roll cells were formed between the main roll cells and then oscillasion offlow occurred.

Effects of magnetic field on the liquid gallium thermosyphon fluid flow; a numerical study

“…They demonstrated that at the critical Grashof numbers, periodic oscillations appear in the fluid flow. Kamakura and Ozoe (1996) numerically investigated the oscillatory phenomena in natural convection in a cavity. They considered a law-Prandtl number fluid with Pr = 0.01 and studied the effects of the Rayleigh number and aspect ratio on the fluid flow characteristics such as vortices and oscillatory phenomena.…”

Transient buoyant convection in a 45°‐inclined enclosure heated and cooled on adjacent walls

“…Despite the practical importance of transient effects in many enclosure‐natural convection cases present in practice, accounts of this situation are relatively scarce when compared to the steady‐state regime (Lage and Bejan, 1993; Fusegi and Hyun, 1994; Kwak and Hyun, 1996). For an enclosure exposed to a sudden vertical temperature difference, Patterson and Imberger (1980) presented a classical configuration for the transient process, which has then been examined by many other researchers (Yewell et al , 1982; Patterson, 1984; Ivey, 1984; Schladow et al , 1989; Paolucci and Chenoweth, 1989; Schladow, 1990; Paolucci, 1990; Patterson and Armfield, 1990; Armfield and Patterson, 1991; Jeevaraj and Patterson, 1992; Hyun and Lee, 1988; Wakatani, 1996; Kamakura and Ozoe, 1996; Cless and Prescott, 1996; Tagawa and Ozoe, 1996; Chung and Hyun, 1997; Nishimura et al , 1997) taking into account of effects of some parameters such as Prandtl number, temperature‐dependent viscosity, numerical schemes used, wall conduction, temperature‐dependent density. Another scarcity of information in the existing literature is related to boundary conditions different to either a horizontally or a vertically imposed temperature difference, which are often expected to be encountered in practice (Poulikakos, 1985; November and Nansteel, 1987; Ganzarolli and Milanez, 1995).…”