Stagg G W, Parker N G, Barenghi C F
Joint Quantum Centre (JQC) Durham-Newcastle, School of Mathematics and Statistics, Newcastle University, Newcastle upon Tyne, NE1 7RU, United Kingdom.
Phys Rev Lett. 2017 Mar 31;118(13):135301. doi: 10.1103/PhysRevLett.118.135301. Epub 2017 Mar 28.
We model the superfluid flow of liquid helium over the rough surface of a wire (used to experimentally generate turbulence) profiled by atomic force microscopy. Numerical simulations of the Gross-Pitaevskii equation reveal that the sharpest features in the surface induce vortex nucleation both intrinsically (due to the raised local fluid velocity) and extrinsically (providing pinning sites to vortex lines aligned with the flow). Vortex interactions and reconnections contribute to form a dense turbulent layer of vortices with a nonclassical average velocity profile which continually sheds small vortex rings into the bulk. We characterize this layer for various imposed flows. As boundary layers conventionally arise from viscous forces, this result opens up new insight into the nature of superflows.
我们对液氦在由原子力显微镜描绘的金属丝粗糙表面（用于实验产生湍流）上的超流进行建模。格罗斯 - 皮塔耶夫斯基方程的数值模拟表明，表面上最尖锐的特征会在内部（由于局部流体速度升高）和外部（为与流动方向一致的涡旋线提供钉扎位点）引发涡旋成核。涡旋相互作用和重新连接有助于形成一个密集的涡旋湍流层，其具有非经典的平均速度分布，该分布不断向主体中释放小涡旋环。我们对各种施加的流动情况对该层进行了表征。由于边界层通常由粘性力产生，这一结果为超流的本质提供了新的见解。
