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ISSN Online: 2377-424X

ISBN Print: 1-56032-797-9

International Heat Transfer Conference 11
August, 23-28, 1998, Kyongju, Korea

MULTIPLE SOLUTIONS IN A NARROW HORIZONTAL AIR-FILLED ANNULUS

Get access (open in a dialog) DOI: 10.1615/IHTC11.3640
pages 175-180

Abstract

Numerical investigations have been carried out to clarify and extend existing knowledge of multicellular natural convective flows in narrow horizontal air-filled concentric annuli. Multiplicity in the multicellular upper flows has been often reported in the literature. The existence of a transcritical bifurcation would explain this, the multiplicity being due to the two stable branches of the bifurcation. The occurrence and the merging of the buoyancy-driven cells have been proved to be identical on both branches. The appearance of another secondary flow, hydrodynamic in origin, inside the crescent base flow in the vertical portions of the annulus, has also been demonstrated at moderate Rayleigh numbers. Increasing the Rayleigh number leads to a reverse transition from multicellular to monocellular flow pattern. Moreover, a critical radius ratio has been numerically detected around 1.16, above which no shear-driven instabilities can develop.