论文标题
确定有效的运动粘度，用于超级流体$^4 $ He中的准经典湍流衰减
Determination of the effective kinematic viscosity for the decay of quasiclassical turbulence in superfluid $^4$He
论文作者
论文摘要
超级流体$^4 $ He（He II）中准经典同质性动荡的能量耗散受到有效的运动粘度$ν'$的控制，它将能源衰减率$ de/dt $与量化的涡流$ l $ l $ a as $ de/dt = - dt = - （ $ν'$的确切价值对于发展我们对He II中的耗散机制的理解至关重要，在许多高雷诺数数字湍流实验和模型测试中也需要使用He II作为工作流体。但是，可靠的$ν'$确定需要$ e（t）$和$ l（t）$的测量，这是从未实现的。在这里，我们讨论了我们对在1 K以上的He II衰减中出现的准经典湍流的研究。我们能够使用最近开发的流动可视化技术来测量$ e（t）$，通过第二声音衰减来测量$ e（t）$。我们报告了$ν'$值在较宽的温度范围内首次确定的，从$ e（t）$和$ l（t）$的时间演变进行比较。
The energy dissipation of quasiclassical homogeneous turbulence in superfluid $^4$He (He II) is controlled by an effective kinematic viscosity $ν'$, which relates the energy decay rate $dE/dt$ to the density of quantized vortex lines $L$ as $dE/dt=-{ν'}(κL)^2$. The precise value of $ν'$ is of fundamental importance in developing our understanding of the dissipation mechanism in He II, and it is also needed in many high Reynolds number turbulence experiments and model testing that use He II as the working fluid. However, a reliable determination of $ν'$ requires the measurements of both $E(t)$ and $L(t)$, which was never achieved. Here we discuss our study of the quasiclassical turbulence that emerges in the decay of thermal counterflow in He II at above 1 K. We were able to measure $E(t)$ using a recently developed flow visualization technique and $L(t)$ via second sound attenuation. We report the $ν'$ values in a wide temperature range determined for the first time from a comparison of the time evolution of $E(t)$ and $L(t)$.
