DNS of heat transfer in a transitional channel flow accompanied by a turbulent puff-like structure
DNS of heat transfer in a transitional channel flow accompanied by a turbulent puff-like structure
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DOI：
10.1615/ichmt.2006.turbulheatmasstransf.300
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发表时间：
2014-06
期刊：
影响因子：
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通讯作者：
T. Tsukahara;K. Iwamoto;H. Kawamura;T. Takeda
中科院分区：
文献类型：
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作者：
T. Tsukahara;K. Iwamoto;H. Kawamura;T. Takeda
基于摩擦速度和通道半宽度$\delta$，在摩擦雷诺数为60 ~ 180的范围内，对充分发展的通道流中的湍流换热进行了直接数值模拟，重点研究了喷流结构和大尺度空间不稳定性。在雷诺数小于80的情况下，采用51.2 x 2 x 22.5的大计算区域，观察到了湍流烟团，并发现了其对动量和热量传输的显著影响。考虑到两种不同的热边界条件，研究了平衡烟团或局部湍流的空间结构：均匀的热流加热和恒定的壁间温差。结果表明，在绕流流场中存在一个局部的强湍流区，沿该区域沿着诱导出展向二次流。因此，在目前的最低雷诺数低至60，流动保持湍流和较大的努塞尔数比那些没有喷烟的喷烟的存在下获得。
Direct numerical simulations of turbulent heat transfer in fully-developed channel flows have been performed in a range of friction Reynolds number between 60 and 180, based on the friction velocity and the channel half width $\delta$, with emphasis on a puff-like structure, large-scale spatial intermittency. For the Reynolds numbers lower than 80 with a large computational domain of 51.2 x 2 x 22.5, the turbulent puff was observed and its significant influences on the momentum and heat transports were found. The spatial structure of the equilibrium puff, or the localized turbulence, was examined with taking account of two different thermal boundary conditions: the uniform heat-flux heating and the constant temperature difference between the walls. It was revealed that there existed a localized strong turbulent region in the form of an oblique band, along which a spanwise secondary flow was induced. In consequence, at the present lowest Reynolds number as low as 60, the flow remained turbulent and the larger Nusselt numbers than those without puff was obtained by the presence of puff.