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Advances in Aircraft and Spacecraft Science   Volume 5, Number 4, July 2018, pages 411-430
Influence of fin partitioning of a Rayeigh-Bénard cavity at low Rayleigh numbers
Adis Zilic and Darren L. Hitt

Abstract     [Full Text]
    This computational study examines the augmentation of classic 2-D Rayleigh-Bénard convection by the addition of periodically-spaced transverse fins. The fins are attached to the heated base of the cavity and serve to partition the cavity into \'units\'with different aspect ratios. The respective impacts upon heat transfer of the fin configuration parameters – including spacing, height, thickness and thermal conductivity – are systematically examined through numerical simulations for a range of laminar Rayleigh numbers (0 < Ra < 2 x 100000) and reported in terms of an average Nusselt number. The selection of the low Rayleigh number regime is linked to likely scenarios within aerospace applications (e.g. avionics cooling) where the cavity length scale and/or gravitational acceleration is small. The net heat transfer augmentation is found to result from a combination of competing fin effects, most of which are hydrodynamic in nature. Heat transfer enhancement of up to 1.2 x that for a Rayleigh-Bénard cavity without fins was found to occur under favorable fin configurations. Such configurations are generally characterized by short, thin fins with half-spacings somewhat less than the convection cell diameter from classic Rayleigh-Bénard theory. In contrast, for unfavorable configurations, it is found that the introduction of fins can result in a significant reduction in the heat transfer performance.
Key Words
    natural convection; Rayleigh-Bénard cells; low Rayleigh number; passive cooling; heat transfer with partitions
Department of Mechanical Engineering, University of Vermont, Burlington, Vermont, USA

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