Quantum mechanics places significant restrictions on the hydrodynamics of superfluid flows. Despite this it has been observed that turbulence in superfluids can, in a statistical sense, share many of the properties of its classical brethren; coherent bundles of superfluid vortices are often invoked as an important feature leading to this quasiclassical behavior. A recent experimental study [E. Rusaouen, B. Rousset, and P.-E. Roche, Europhys. Lett. 118, 14005, (2017)] inferred the presence of these bundles through intermittency in the pressure field; however, direct visualization of the quantized vortices to corroborate this finding was not possible. In this work, we performed detailed numerical simulations of superfluid turbulence at the level of individual quantized vortices through the vortex filament model. Through course graining of the turbulent fields, we find compelling evidence supporting these conclusions at low temperature. Moreover, elementary simulations of an isolated bundle show that the number of vortices inside a bundle can be directly inferred from the magnitude of the pressure dip, with good theoretical agreement derived from the Hall-Vinen-Bekarevich-Khalatnikov (HVBK) equations. Full simulations of superfluid turbulence show strong spatial correlations between course-grained vorticity and low-pressure regions, with intermittent vortex bundles appearing as deviations from the underlying Maxwellian (vorticity) and Gaussian (pressure) distributions. Finally, simulations of a decaying random tangle in an ultraquantum regime show a unique fingerprint in the evolution of the pressure distribution, which we argue can be fully understood using the HVBK framework.

中文翻译：

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超流体湍流中的粗粒度压力动力学

量子力学极大地限制了超流体的流体动力学。尽管如此，从统计意义上讲，已经观察到超流体中的湍流可以共享其经典弟兄的许多特性。通常将超流体涡旋的相干束作为导致这种准经典行为的重要特征。最近的一项实验研究[E. Rusaouen，B.Rousset和P.-E。罗氏，Europhys。来吧 118，14005，（2017）]通过压力场的间歇性推断这些束的存在；但是，无法直接可视化量化的涡旋以证实这一发现。在这项工作中，我们通过涡流丝模型在单个量化涡水平上进行了超流体湍流的详细数值模拟。通过对湍流场进行粗化处理，我们发现了令人信服的证据，这些证据支持了低温下的这些结论。此外，对孤立束的基本模拟表明，可以从压力骤降的大小直接推断束中的旋涡数，并且可以从Hall-Vinen-Bekarevich-Khalatnikov（HVBK）方程得出良好的理论一致性。对超流体湍流的完整模拟显示出过程颗粒状涡度与低压区域之间存在强烈的空间相关性，间歇性涡旋束表现为与基础Maxwellian（涡度）和Gaussian（压力）分布的偏差。最后，对超量子态中的一个随机衰变缠结的仿真显示了压力分布演变过程中的唯一指纹，我们认为可以使用HVBK框架充分理解这一点。