A numerical study of mixed convection in a vertical channel flow impinging on a horizontal surface
A numerical study of mixed convection in a vertical channel flow impinging on a horizontal surface
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垂直通道流撞击水平表面混合对流的数值研究
DOI：
10.1016/j.ijthermalsci.2006.11.012
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发表时间：
2007
影响因子：
4.5
通讯作者：
A. Beshkani
中科院分区：
文献类型：
--
作者：
M. Nobari;A. Beshkani
本文采用基于投影算法的有限差分方法，对水平等温线面上垂直通道内的混合对流进行了数值模拟。控制方程在空间上用二阶中心差分离散，在时间上用一阶中心差分离散。考虑由Reynolds和Richardson（或Grashof）数组成的无因次参数，在不同面积的各种垂直通道的水平面上计算平均努塞尔数。分析结果表明，存在一个使表面传热率达到最大的最佳间隙。最佳间隙值随通道的Grashof数、雷诺数和入口长度的变化而变化，但在理查德森数较大时，Nu随间隙大小的减小而增大。随着Re、Gr和Ri数的增加，Nu数增加，但在Ri为0.1和0.01时，Nu数的变化基本相似。此外，对于水平表面的传热，发散通道通常比收敛通道更有效。对普朗特数和通道不对称性的影响也进行了详细的研究。
In this study, mixed convection in a vertical channel flow discharging over a horizontal isotherm surface is investigated numerically using a finite difference method based on projection algorithm. The governing equations are discretized by a second order central difference in space and first order in time. The average Nusselt number is calculated on the horizontal surface in various vertical channels of varying areas considering non-dimensional parameters consisting of Reynolds and Richardson (or Grashof) numbers. Analysis of the results shows that there is an optimum gap to have a maximum heat transfer rate over the surface. The optimum gap value varies with Grashof and Reynolds numbers and inlet length of the channel but for high Richardson numbers, Nu has an increasing trend with reduction of gap size. By increasing the Re, Gr and Ri numbers, Nu number increases but in Ri of 0.1 and 0.01 the variations are approximately similar to each other. In addition, a divergent channel is usually more efficient than convergent one concerning heat transfer over the horizontal surface. Effects of Prandtl number and asymmetricity in channel are investigated in detail too.