Large-scale turbulent flow around a cylinder in counterflow superfluid4He (He (II))
Large-scale turbulent flow around a cylinder in counterflow superfluid4He (He (II))
复制标题
逆流超流体中圆柱体周围的大规模湍流4He (He (II))
DOI：
10.1038/nphys114
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发表时间：
2005
期刊：
影响因子：
19.6
通讯作者：
S. V. Van Sciver
中科院分区：
文献类型：
--
作者：
Tao Zhang;S. V. Van Sciver
圆柱体上流体流动的详细性质是经典流体动力学的基本主题之一，因为它演示了流动分离和旋涡脱落1。在超流氦中，无论是He（II）还是3He的B相，一个重要的问题是这些量子流体在多大程度上表现出经典的流体湍流状态2，3，4。虽然湍流结构的存在可以使用精确的仪器来推断5，6，但流场的直接可视化可以提供这些现象的明确证据。在这里，我们显示了大的湍流结构的存在下，在He（II）的逆流通过一个圆柱体的粒子图像测速技术。与经典的流体流动相比，由He（II）逆流驱动的粒子运动显示宏观的圆柱体下游的涡流，但也观察到类似的结构在前面的圆柱体，行为没有看到在经典流体。由于He（II）的朗道双流体模型7将逆流描述为超流体和正常流体成分的相对运动，因此目前的结果表明，这两种成分在经过圆柱体时可能正在经历一种流动分离。
The detailed nature of fluid flow over a cylinder is one of the fundamental topics in classical fluid dynamics as it demonstrates flow separation and vortex shedding1. In superfluid helium, either He (II) or the B phase of3He, an important question has been to what extent these quantum fluids show classical fluid turbulent states2,3,4. Although the existence of turbulent structures can be inferred using precise instrumentation5,6, direct visualization of the flow field can provide unequivocal evidence of these phenomena. Here we show the existence of large turbulent structures in He (II) counterflow across a cylinder as obtained by the particle image velocimetry technique. Compared with classical fluid flow, the particle motion driven by He (II) counterflow shows macroscopic eddies downstream of the cylinder but also similar structures are observed in front of the cylinder, behaviour not seen in classical fluids. As Landau’s two-fluid model7 for He (II) describes counterflow as the relative motion of the superfluid and normal fluid components, the current results indicate that both components may be undergoing a kind of flow separation as they pass over the cylinder.