Mixed convection flow and heat transfer across a square cylinder under the influence of aiding buoyancy at low Reynolds numbers
Mixed convection flow and heat transfer across a square cylinder under the influence of aiding buoyancy at low Reynolds numbers
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DOI：
10.1016/j.ijheatmasstransfer.2011.12.034
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发表时间：
2012-04
影响因子：
5.2
通讯作者：
N. Sharma;A. Dhiman;Surendra Kumar
中科院分区：
文献类型：
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作者：
N. Sharma;A. Dhiman;Surendra Kumar
本文研究了垂直无约束（雷诺数Re=1-40，理查森数Ri=0-1）条件下，在辅助浮力作用下，方形截面长圆柱绕流的混合对流与换热。在同位网格上采用半显式有限体积法求解控制方程，沿着适当的边界条件。对于Ri=0、0.5和1，流动分离的开始分别发生在Re=1-2之间、Re=2-3之间和Re=3-4之间。流动被发现是稳定的条件范围内研究这里。摩擦系数、压力系数和总阻力系数随Richardson数的增加而增加，随着辅助浮力的影响增加，雷诺数恒定时阻力系数增加。在普朗特数为0.7（空气）的障碍物周围的温度场的等温线。局部和平均努塞尔数的计算给出了一个详细的研究，传热的每一个表面的方柱和整体的传热率，它被发现，传热增加，增加雷诺数和/或理查森数。在本工作所涵盖的条件范围内，得到了尾迹长度和平均圆柱努塞尔数的简单表达式。
In this paper, mixed convection flow and heat transfer around a long cylinder of square cross-section under the influence of aiding buoyancy are investigated in the vertical unconfined configuration (Reynolds number, Re=1–40 and Richardson number, Ri=0–1). The semi-explicit finite volume method implemented on the collocated grid arrangement is used to solve the governing equations along with the appropriate boundary conditions. The onset of flow separation occurs between Re=1–2, between Re=2–3 and between Re=3–4 for Ri=0, 0.5 and 1, respectively. The flow is found to be steady for the range of conditions studied here. The friction, pressure and total drag coefficients are found to increase with Richardson number, i.e., as the influence of aiding buoyancy increases drag coefficients increase at the constant value of the Reynolds number. The temperature field around the obstacle is presented by isotherm contours at the Prandtl number of 0.7 (air). The local and average Nusselt numbers are calculated to give a detailed study of heat transfer over each surface of the square cylinder and an overall heat transfer rate and it is found that heat transfer increases with increase in Reynolds number and/or Richardson number. The simple expressions for the wake length and average cylinder Nusselt number are obtained for the range of conditions covered in this work.