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THMT-12. Proceedings of the Seventh International Symposium On Turbulence Heat and Mass Transfer
September, 24-27, 2012, Palermo, Italy

DOI: 10.1615/ICHMT.2012.ProcSevIntSympTurbHeatTransfPal


ISBN Print: 978-1-56700-302-4

ISSN: 2377-2816

LES and URANS strategies for the computation of turbulent natural convection flow inside an annular horizontal penetration enclosure

pages 1660-1672
DOI: 10.1615/ICHMT.2012.ProcSevIntSympTurbHeatTransfPal.1700
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SINOPSIS

Turbulent natural convection flow inside a horizontal penetration enclosure has been performed using a highly resolved large eddy simulation (LES) and a set of RANS models including the k−ε model [7] with standard wall-function, and the SST k−ω scheme [10]. The penetration cavity consists of a horizontal annulus (of length-to-diameter ratio 16.56), the inner wall of which is cooled, whilst the outer is insulated. The cavity is closed at one end and connected to a large reservoir of hot fluid at the other. The fluid is CO2, with a Prandtl number of 0.7, giving a Rayleigh number of 1.5 × 109. The LES results show that the instantaneous field includes many structures inside the penetration. These structures are dispersed along the length of the penetration and outside towards the outlet of the surrounding domain. Results obtained from the LES and URANS simulations suggest that there is a general downward fluid motion inside the penetration. The SST k−ω scheme agrees better than the k−ε model with the present LES in the fact that the flow is unsteady and there are large-scale oscillations present which decrease in amplitude as one moves from the open towards the closed end of the annular enclosure. Results obtained from the standard k−ε model show that the flow reaches a steady state. Overall heat transfer and thermal quantitative results show that RANS models are in close agreement with the current LES data.

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