Finne A P, Araki T, Blaauwgeers R, Eltsov V B, Kopnin N B, Krusius M, Skrbek L, Tsubota M, Volovik G E
Low Temperature Laboratory, Helsinki University of Technology, PO Box 2200, FIN-02015 HUT, Finland.
Nature. 2003 Aug 28;424(6952):1022-5. doi: 10.1038/nature01880.
Hydrodynamic flow in classical and quantum fluids can be either laminar or turbulent. Vorticity in turbulent flow is often modelled with vortex filaments. While this represents an idealization in classical fluids, vortices are topologically stable quantized objects in superfluids. Superfluid turbulence is therefore thought to be important for the understanding of turbulence more generally. The fermionic 3He superfluids are attractive systems to study because their characteristics vary widely over the experimentally accessible temperature regime. Here we report nuclear magnetic resonance measurements and numerical simulations indicating the existence of sharp transition to turbulence in the B phase of superfluid 3He. Above 0.60T(c) (where T(c) is the transition temperature for superfluidity) the hydrodynamics are regular, while below this temperature we see turbulent behaviour. The transition is insensitive to the fluid velocity, in striking contrast to current textbook knowledge of turbulence. Rather, it is controlled by an intrinsic parameter of the superfluid: the mutual friction between the normal and superfluid components of the flow, which causes damping of the vortex motion.
经典流体和量子流体中的流体动力学流动可以是层流或湍流。湍流中的涡度通常用涡旋丝来建模。虽然这在经典流体中是一种理想化，但涡旋在超流体中是拓扑稳定的量子化物体。因此，超流体湍流被认为对于更普遍地理解湍流很重要。费米子³He超流体是有吸引力的研究系统，因为它们的特性在实验可及的温度范围内变化很大。在此，我们报告核磁共振测量和数值模拟结果，表明超流体³He的B相存在向湍流的急剧转变。高于0.60T(c)（其中T(c)是超流转变温度）时，流体动力学是规则的，而低于此温度时，我们观察到湍流行为。该转变对流体速度不敏感，这与当前教科书关于湍流的知识形成鲜明对比。相反，它由超流体的一个固有参数控制：流动的正常分量和超流体分量之间的相互摩擦，这会导致涡旋运动的阻尼。
