Turbulence Appearance and Nonappearance in Thin Fluid Layers
Turbulence Appearance and Nonappearance in Thin Fluid Layers
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DOI：
10.1103/physrevlett.121.164501
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发表时间：
2018-10-16
影响因子：
8.6
通讯作者：
Vladimirova, Natalia
中科院分区：
文献类型：
--
作者：
Falkovich, Gregory;Vladimirova, Natalia
流体层中的流动在工业、物理学和天体物理学中是普遍存在的。薄层中的大尺度流动可考虑为二维的，并加上底部摩擦。在这里，我们发现，这种流动的性质显着依赖于他们弧驱动的方式。我们认为，壁驱动（Couctte）流不能维持湍流，无论多么小的粘度和摩擦。雷诺数Re = 10（6）以下的直接数值模拟（DNSs）证实了所有扰动在平面库埃特流中消失。相反，对于足够小的粘度和摩擦，扰动破坏压力驱动的层流（Poiffille）。相反，出现的是一种在壁涡之间滑动的射流形式的行波。对于5 × 10（3）< Re < 3 × 10（4），在大多数情况下，平均流具有非常简单的结构：射流是正弦曲线，具有抛物线速度剖面，涡量在涡内是恒定的，而波动很小。在较高的Re，强烈的波动出现，但平均行波生存。考虑到这种流动中的动量通量障碍，我们推导出一个新的摩擦因子的Re依赖性的标度律，并通过DNS证实。
Flows in fluid layers are ubiquitous in industry, geophysics, and astrophysics. Large-scale flows in thin layers can he considered two dimensional with bottom friction added. Here we find that the properties of such flows depend dramatically on the way they arc driven. We argue that a wall-driven (Couctte) flow cannot sustain turbulence, no matter how small the viscosity and friction. Direct numerical simulations (DNSs) up to the Reynolds number Re = 10(6) confirm that all perturbations die in a plane Couette flow. On the contrary, for sufficiently small viscosity and friction, perturbations destroy the pressure-driven laminar (Poiseuille) flow. What appears instead is a traveling wave in the form of a jet slithering between wall vortices. For 5 x 10(3) < Re < 3 x 10(4), the mean flow in most cases has remarkably simple structure: the jet is sinusoidal with a parabolic velocity profile, and vorticity is constant inside vortices, while the fluctuations are small. At higher Re, strong fluctuations appear, yet the mean traveling wave survives. Considering the momentum flux barrier in such a flow, we derive a new scaling law for the Re dependence of the friction factor and confirm it by DNS.