Laminar natural convection in a square duct from two heated horizontal cylinders: Effect of Prandtl number

Abstract

A detailed numerical study has been carried out for the steady, two-dimensional, laminar natural convection heat transfer from two heated cylinders (equal temperature and radius) immersed in a Newtonian fluid inside a cold square enclosure. The coupled governing differential equations (continuity, momentum and energy) have been solved over the ranges of dimensionless parameters as follows: Grashof number, 102 ≤ Gr ≤ 104 and Prandtl number, 0.7 ≤ Pr ≤ 100. Detailed structure of the flow and temperature fields are presented in terms of the streamlines and isotherm patterns which help delineate the regions of high/low temperatures and general flow characteristics respectively. At the next level, the heat transfer characteristics are presented in terms of the local and average Nusselt number. The dependence of the Nusselt number on the both Grashof and Prandtl numbers is analyzed and it shows a positive dependence on both of the dimensionless parameters, namely, Grashof (Gr) and Prandtl (Pr) number.