Direct numerical simulation of strongly heated air flow in a vertical pipe
Direct numerical simulation of strongly heated air flow in a vertical pipe
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垂直管道内强热气流的直接数值模拟
DOI：
10.1016/j.ijheatmasstransfer.2016.05.038
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发表时间：
2016-10
影响因子：
5.2
通讯作者：
X. Chu;E. Laurien;D. McEligot
中科院分区：
文献类型：
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作者：
X. Chu;E. Laurien;D. McEligot
采用高分辨直接数值模拟方法，研究了雷诺数Re为0=4240和6020时，L=30D竖直管内的强加热空气流动。该模型以Shehata和McEligot(1995)的实验结果为基础，与传热学和流动统计结果吻合较好。在强加热情况下观察到流动再分层现象。采用新的半局部墙坐标法代替传统的墙坐标法。在考虑局部性质变化的半局部壁面坐标下，速度场和温度场都表现出再区域化的过程。湍流强度和雷诺切应力的显著降低也表明了这种再层化。在准层流中，粘性小层变厚。这一层内的湍流呈现出不断增长的各向异性特征。管道中心的湍流变得近乎各向同性。这种双层特征通过流动可视化得到了清晰的表现。
Well-resolved direct numerical simulation (DNS) is applied to investigate strongly heated air flow in a vertical pipe (L= 30 D) at inlet Reynolds numbers of Re 0= 4240 and 6020. The DNS is based on the experimental cases of Shehata and McEligot (1995) and shows excellent agreement with heat-transfer and flow statistical results. Flow relaminarization is observed in the strongly heated cases. We apply a new semi-local wall coordinate to replace the conventional one. With the semi-local wall coordinates, which considers the local property variation, both the velocity and temperature fields show the process of relaminarization. This relaminarization is also indicated by the significant decrease of turbulence intensity and Reynolds shear stress. In the quasi-laminar flow, the viscous sublayer becomes thicker. Turbulence in this layer shows a growing anisotropic character. And turbulence in the pipe center becomes approximately isotropic. This two-layer character is clearly displayed by flow visualization.