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Computational Thermal Sciences: An International Journal
ESCI SJR: 0.249 SNIP: 0.434 CiteScore™: 1.4

ISSN Print: 1940-2503
ISSN Online: 1940-2554

Computational Thermal Sciences: An International Journal

DOI: 10.1615/ComputThermalScien.v3.i1.10
pages 1-14

TRANSIENT CONJUGATED UPWARD AND DOWNWARD MIXED CONVECTION IN A PARTIALLY HEATED THICK PIPE

Abdeslam Omara
Université Frères Mentouri Constantine 1
Said Abboudi
Laboratoire Interdisciplinaire Carnot de Bourgogne, ICB UMR 6303 CNRS, Université Bourgogne Franche Comté (UBFC), UTBM, site de Sévenans 90010 Belfort cedex, France

ABSTRACT

Transient conjugated downward and upward laminar mixed-convection heat transfer in a vertical pipe, partially submitted to a constant heat flux, has been investigated computationally. The governing Navier-Stokes and energy equations were solved by a code developed using the finite volume method and Boussinesq's assumptions. Solutions were obtained for (Pr, Re, Gr) = (5,100, 5 × 105), wall-to-fluid conductivity ratio K = 10, 50, and 100, and pipe thickness-to-diameter ratios Δ = 0.05 and 0.25. From a parametric study, transient distribution of the normalized interfacial heat flux and of the friction coefficient ratio as a function of the axial coordinates as well as transient evolution of the vector velocities were obtained and the effect of K and Δ investigated. It was found that the magnitude and the extent of upstream and downstream heating increase monotonically with an increase of Δ or K. In turn, this heat flux redistribution significantly affects the friction coefficient ratio and velocity field in the downstream and upstream adiabatic sections for the downward and upward mixed-convection cases.


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