An experimental study of the unsteady thermal flow around a thin fin on a sidewall of a differentially heated cavity

Xu, Feng, Patterson, John C., and Lei, Chengwang (2008) An experimental study of the unsteady thermal flow around a thin fin on a sidewall of a differentially heated cavity. International Journal of Heat and Fluid Flow, 29 (4). pp. 1139-1153.

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Abstract

The unsteady thermal flow around a thin fin on a sidewall of a differentially heated cavity is visualized using a shadowgraph technique and measured using fast-response thermistors. Experiments show that the transition of the unsteady thermal flow around the fin from initiation by sudden heating to a quasi-steady state undergoes a number of stages including the formation of a horizontal gravity current under the fin and a starting plume bypassing the fin, entrainment into the downstream thermal boundary layer, and separation and oscillations of the thermal flow above the fin. We present a series of flow visualization images to describe the transition of the unsteady thermal flow, and obtain the unsteady velocity scales of the fronts of the lower intrusion and starting plume as functions of the time and Rayleigh number, which are verified by the results of the flow visualization experiments. In the transition to the quasi-steady state, separation and oscillations of the thermal flow above the fin are observed. It is demonstrated that these oscillations, which are sensitive to the geometry of the fin, trigger instability of the downstream thermal boundary layer flow and thus enhance convection. It is found that the frequency of the oscillations is a linear function of the Rayleigh number.

Item ID: 10067
Item Type: Article (Refereed Research - C1)
Keywords: unsteady thermal flow; fin; oscillations
ISSN: 0142-727X
Funders: Australian Research Council
Date Deposited: 01 Apr 2010 06:03
FoR Codes: 09 ENGINEERING > 0915 Interdisciplinary Engineering > 091504 Fluidisation and Fluid Mechanics @ 50%
09 ENGINEERING > 0915 Interdisciplinary Engineering > 091502 Computational Heat Transfer @ 50%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970109 Expanding Knowledge in Engineering @ 100%
Citation Count from Web of Science Web of Science 13
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