An intrinsic velocity-independent criterion for superfluid turbulence
An intrinsic velocity-independent criterion for superfluid turbulence
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DOI：
10.1038/nature01880
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发表时间：
2003-08-28
期刊：
影响因子：
64.8
通讯作者：
Volovik, GE
中科院分区：
文献类型：
--
作者：
Finne, AP;Araki, T;Volovik, GE
经典流体和量子流体中的流体动力流动可以是层流或湍流。紊流中的涡度通常用涡丝来模拟。虽然这代表了经典流体中的一种理想化，但涡旋是超流体中拓扑稳定的量子化物体。因此，超流体湍流(1)被认为对更普遍地理解湍流是重要的。费米子He-3超流体是有吸引力的研究系统，因为它们的特性在实验可达到的温度范围内变化很大。在这里，我们报告了核磁共振测量和数值模拟，表明在超流体He-3的B相中存在向湍流的急剧过渡。高于0.60T(c)（其中T-c是超流体的转变温度），流体力学是规则的，而低于这个温度，我们看到湍流行为。过渡对流体速度不敏感，这与目前教科书上关于湍流的知识形成鲜明对比(2)。相反，它是由超流体的一个固有参数控制的：流动的正常分量和超流体分量之间的相互摩擦，这导致了涡流运动的阻尼。
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(1) is therefore thought to be important for the understanding of turbulence more generally. The fermionic He-3 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 He-3. 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(2). 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.