Natural convection and heat transfer in attics subject to periodic thermal forcing

Saha, Suvash C., Patterson, John C., and Lei, Chengwang (2010) Natural convection and heat transfer in attics subject to periodic thermal forcing. International Journal of Thermal Sciences, 49 (10). pp. 1899-1910.

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Abstract

The heat transfer through the attics of buildings under realistic thermal forcing has been considered in this study. A periodic temperature boundary condition is applied on the sloping walls of the attic to show the basic flow features in the attic space over diurnal cycles. The numerical results reveal that, during the daytime heating stage, the flow in the attic space is stratified; whereas at the night-time cooling stage, the flow becomes unstable. A symmetrical solution is seen for relatively low Rayleigh numbers. However, as the Ra gradually increases, a transition occurs at a critical value of Ra. Above this critical value, an asymmetrical solution exhibiting a pitchfork bifurcation arises at the night-time. It is also found that the calculated heat transfer rate at the night-time cooling stage is much higher than that during the daytime heating stage.

Item ID: 16919
Item Type: Article (Research - C1)
ISSN: 1290-0729
Keywords: natural convection, periodic condition, asymmetric flow, Nusselt number, stream lines
Date Deposited: 15 May 2011 06:55
FoR Codes: 09 ENGINEERING > 0915 Interdisciplinary Engineering > 091504 Fluidisation and Fluid Mechanics @ 100%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970109 Expanding Knowledge in Engineering @ 100%
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