The present work is concerned with the modelling of ascending turbulent ('mixed convection') flow in a vertical heated pipe. All fluid properties are assumed to be constant and buoyancy is accounted for within the Boussinesq approximation. Four Eddy Viscosity Models (EVMs) are examined against experimental measurements and the direct numerical simulation data of You et al. [2003]. The EVMs embody distinct physical refinements with respect to the parent high-Reynolds-number k-ε model. Large Eddy Simulations (LES) employing the classical Smagorinsky sub-grid-scale model are also presented. Three different CFD codes have been employed in the study: 'CONVERT', 'Code_Saturne', and 'STAR-CD', which are respectively in-house, industrial, and commercial packages. In relation to forced convection Nusselt number and local friction coefficient, discrepancies are identified between 'reference' data sources, namely earlier DNS and experimental results and the present LES computations. The Launder-Sharma closure [Launder and Sharma, 1974] is in the closest agreement with DNS results for levels of heat transfer impairment in ascending mixed convection flow, although again there is a lack of consensus between reference sources.
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