论文标题
在低温下衰减量子湍流中的活性和有限尺寸颗粒
Active and finite-size particles in decaying quantum turbulence at low temperature
论文作者
论文摘要
在存在有限大小的活性粒子的情况下，通过数值模拟GROSS-PITAEVSKII方程的数值模拟研究了量子涡流的湍流缠结的演变。将颗粒建模为耗尽超流体的电势，并在牛顿动力学后用经典的自由度描述。结果表明，颗粒不会改变超级流体Kolmogorov湍流制度的建筑物和衰减。据观察，尽管偶尔会被脱离并重新捕获，但几乎整体粒子仍然被困在量子涡旋中。介绍和讨论了此过程的统计数据。还研究了粒子拉格朗日动力学。在很大的时间尺度上，颗粒的速度光谱让人想起经典的拉格朗日湍流行为。在时间尺度的速度比与平均涡流间距离相关的周转时间快，由于马格努斯效应，粒子运动以振荡为主。对于光颗粒，出现了光谱的非古典缩放。然后研究粒子速度和加速度概率分布函数。发现粒子加速度的去相关时间比经典流体短，并且与被困颗粒所经历的马格努斯力有关。
The evolution of a turbulent tangle of quantum vortices in presence of finite-size active particles is studied by means of numerical simulations of the Gross-Pitaevskii equation. Particles are modeled as potentials depleting the superfluid and described with classical degrees of freedom following a Newtonian dynamics. It is shown that particles do not modify the building-up and the decay of the superfluid Kolmogorov turbulent regime. It is observed that almost the totality of particles remains trapped inside quantum vortices, although they are occasionally detached and recaptured. The statistics of this process are presented and discussed. The particle Lagrangian dynamics is also studied. At large time scales, the velocity spectrum of particles is reminiscent of a classical Lagrangian turbulent behavior. At time-scales faster than the turnover time associated to the mean inter-vortex distance, the particle motion is dominated by oscillations due to Magnus effect. For light particles a non-classical scaling of the spectrum arises. The particle velocity and acceleration probability distribution functions are then studied. The decorrelation time of the particle acceleration is found to be shorter than in classical fluids, and related to the Magnus force experienced by the trapped particles.
