Thermally and mechanically driven quantum turbulence in helium II
Thermally and mechanically driven quantum turbulence in helium II
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DOI：
10.1103/physrevb.86.104501
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发表时间：
2012-09-04
影响因子：
3.7
通讯作者：
Sergeev, Y. A.
中科院分区：
文献类型：
--
作者：
Baggaley, A. W.;Sherwin, L. K.;Sergeev, Y. A.
在大多数超流氦实验中，湍流是通过热方式（通过施加热通量，如热逆流）或机械方式（通过搅拌液体）产生的。通过将超流体涡线建模为重新连接具有固定循环的空间曲线，并将驱动法向流体建模为均匀流（对于热逆流）和合成湍流（对于机械驱动的湍流），我们确定了热驱动和机械驱动的量子湍流之间的差异。我们发现，在机械驱动的湍流中，能量集中在大尺度上，光谱服从柯尔莫哥洛夫缩放，涡旋线具有大曲率，并且相干涡旋结构的存在会引起小角度的涡旋重连接。相反，在热驱动湍流中，能量集中在中尺度，曲率较小，涡度场无特征，重连接发生在较大角度。我们的结果提出了一种通过实验检测超流体涡束存在的方法。
In most experiments with superfluid helium, turbulence is generated thermally (by applying a heat flux, as in thermal counterflow) or mechanically (by stirring the liquid). By modeling the superfluid vortex lines as reconnecting space curves with fixed circulation, and the driving normal fluid as a uniform flow (for thermal counterflow) and a synthetic turbulent flow (for mechanically driven turbulence), we determine the difference between thermally and mechanically driven quantum turbulence. We find that in mechanically driven turbulence, the energy is concentrated at the large scales, the spectrum obeys Kolmogorov scaling, vortex lines have large curvature, and the presence of coherent vortex structures induces vortex reconnections at small angles. On the contrary, in thermally driven turbulence, the energy is concentrated at the mesoscales, the curvature is smaller, the vorticity field is featureless, and reconnections occur at larger angles. Our results suggest a method to experimentally detect the presence of superfluid vortex bundles.