论文标题
三维湍流流动
The three-dimensional turbulent cellular flow
论文作者
论文摘要
我们通过广泛的直接数值模拟研究，在具有周期性边界条件的立方盒中，由二维细胞强迫产生的湍流。尽管强迫的各向异性具有强大的各向异性，但我们发现湍流在小尺度上恢复了几乎完全的各向同性。但是，强迫的特征仍保留在平均流动中（随时间和均匀方向平均），这允许引入一个摩擦因子，该因子的依赖对雷诺数的依赖进行了研究。我们进一步发现，由于强大尺度上强制平均流量与小尺度上的湍流波动之间的交换，该流量的特征是总能量的较大时间波动。这种时间波动会对能量谱进行校正，这可以通过简单的维度参数来解释。
We study, by means of extensive direct numerical simulations, the turbulent flow produced by a two-dimensional cellular forcing in a cubic box with periodic boundary conditions. In spite of the strong anisotropy of the forcing, we find that turbulence recovers almost complete isotropy at small scales. Nonetheless, the signature of the forcing remains in the mean flow (averaged over time and over the homogeneous direction) and this allows to introduce a friction factor, whose dependence on the Reynolds number is investigated. We further find that the flow is characterized by large temporal fluctuations of the total energy, as a consequence of the exchange between the forced mean flow at large scales and turbulent fluctuations at small scales. Such temporal fluctuations produce a correction to the energy spectrum that can be explained by a simple dimensional argument.
