标题： 湍流通道流动的DNS在非常低的雷诺数下 显示英文标题

标题： DNS of turbulent channel flow at very low Reynolds numbers

摘要： 直接数值模拟（DNS）了非常低雷诺数下的充分发展湍流通道流动，其计算箱尺寸比现有DNS更大。 摩擦雷诺数降低到60，其中摩擦雷诺数是基于摩擦速度和通道半宽度计算的。 当雷诺数降低到60且计算箱尺寸较小时，流动变为层流。 使用大箱，我们发现局部湍流以周期性斜带的形式持续存在。 这种局部无序流动类似于过渡管道流动中的平衡湍流泡。 提供了各种湍流统计量，如湍流强度、涡度波动和雷诺应力。 特别是，针对雷诺数依赖性和计算箱尺寸的影响，讨论了它们的近壁渐进行为和湍流动能预算项。 还介绍了并讨论了与湍流结构相关的其他详细特征。 显示英文摘要

摘要： Direct numerical simulations (DNS) of fully-developed turbulent channel flows for very low Reynolds numbers have been performed with a larger computational box sizes than those of existing DNS. The friction Reynolds number was decreased down to 60, where the friction Reynolds number is based on the friction velocity and the channel half width. When the Reynolds number was decreased to 60 with small computational box size, the flow became laminar. Using a large box, we found that a localized turbulence was observed to sustain in the form of periodic oblique band. This type of locally disordered flow is similar to a equilibrium turbulent puff in a transitional pipe flow. Various turbulence statistics such as turbulence intensities, vorticity fluctuations and Reynolds stresses are provided. Especially, their near-wall asymptotic behavior and budget terms of turbulence kinetic energy were discussed with respect to the Reynolds-number dependence and an influence of the computational box size. Other detailed characteristics associated with the turbulence structures were also presented and discussed.