Varga E, Vadakkumbatt V, Shook A J, Kim P H, Davis J P
Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada.
Phys Rev Lett. 2020 Jul 10;125(2):025301. doi: 10.1103/PhysRevLett.125.025301.
Turbulent flow restricted to two dimensions can spontaneously develop order on large scales, defying entropy expectations and in sharp contrast with turbulence in three dimensions where nonlinear turbulent processes act to destroy large-scale order. In this work we report the observation of unusual turbulent behavior in steady-state flow of superfluid ^{4}He-a liquid with vanishing viscosity and discrete vorticity-in a nearly two-dimensional channel. Surprisingly, for a range of experimental parameters, turbulence is observed to exist in two bistable states. This bistability can be well explained by the appearance of large-scale regions of flow of opposite vorticity.
局限于二维的湍流能够在大尺度上自发地形成有序结构，这违背了熵的预期，并且与三维湍流形成鲜明对比，在三维湍流中，非线性湍流过程会破坏大尺度的有序性。在这项工作中，我们报告了在超流^4He（一种粘度消失且具有离散涡度的液体）在近乎二维的通道中的稳态流动中观察到的异常湍流行为。令人惊讶的是，在一系列实验参数范围内，观察到湍流存在于两种双稳态中。这种双稳态可以通过相反涡度的大尺度流动区域的出现得到很好的解释。
