Statistics of Intermittent Switching between Potential Flow and Turbulence around an Oscillating Sphere in Superfluid 4He below 0.5 K
Statistics of Intermittent Switching between Potential Flow and Turbulence around an Oscillating Sphere in Superfluid 4He below 0.5 K
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0.5 K 以下超流体 4He 中振荡球体周围势流和湍流之间间歇切换的统计
DOI：
10.1007/s10909-010-0208-1
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发表时间：
2010
影响因子：
2
通讯作者：
W. Schoepe
中科院分区：
文献类型：
--
作者：
W. Schoepe
已知超流氦在极低温度下围绕振荡微球的流动在略高于临界速度时不稳定。流动模式在势流和湍流之间间歇地切换。根据在恒定温度和驱动力下记录的时间序列，讨论了开关现象的统计特性。基于我们最近对振荡超流的临界速度 vc 的理解，即 $v_{c}\sim \sqrt{\kappa\,\omega}$，其中 κ 是循环量子，ω 是振荡频率，现在正在完善分析。根据湍流相寿命的指数分布，可以推断出涡密度 L 的定量信息，例如 L 的分布和波动宽度。势流的相显示出超出湍流振幅的瑞利分布。发现均方根值缩放为 ω−3/2。
The flow of superfluid helium at very low temperatures around an oscillating microsphere is known to be unstable slightly above the critical velocity. The flow pattern switches intermittently between potential flow and turbulence. From time series recorded at constant temperature and driving force the statistical properties of the switching phenomenon are discussed. Based on our recent understanding of the critical velocity vc of oscillatory superflows, i.e., $v_{c}\sim \sqrt{\kappa\,\omega}$, where κ is the circulation quantum and ω is the oscillation frequency, the analysis is being refined now. From the exponential distribution of the lifetimes of the turbulent phases quantitative information on the vortex density L can be inferred such as the distribution and the width of the fluctuations of L. The phases of potential flow show a Rayleigh distribution of the excess oscillation amplitude above the amplitude at turbulent flow. The rms value is found to scale as ω−3/2.
影响因子：
8.6
作者：
Hof, Bjoern;de Lozar, Alberto;Westerweel, Jerry
通讯作者：
Westerweel, Jerry