Tay Fuyang, Zhang Youming, Xu Hongyi, Goh Honghui, Luo Yu, Zhang Baile
Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore.
School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore.
Natl Sci Rev. 2021 Nov 17;9(9):nwab205. doi: 10.1093/nsr/nwab205. eCollection 2022 Sep.
The model of ideal fluid flow around a cylindrical obstacle exhibits a long-established physical picture, where originally straight streamlines are deflected over the whole space by the obstacle. Inspired by transformation optics and metamaterials, recent theories have proposed the concept of fluid cloaking, which is able to recover the straight streamlines, as if the obstacle did not exist. However, such a cloak, similar to all previous transformation-optics-based devices, relies on complex metamaterials with inhomogeneous parameters and is difficult to implement. Here we deploy the theory of scattering cancellation and report on the experimental realization of a fluid-flow cloak without metamaterials. This cloak is realized by engineering the geometry of the fluid channel, which effectively cancels the dipole-like scattering of the obstacle. The cloaking effect is demonstrated through the direct observation of recovered straight streamlines in the fluid flow. Our work sheds new light on conventional fluid control and may find application in microfluidic devices.
围绕圆柱形障碍物的理想流体流动模型展现出一幅早已确立的物理图景，即原本笔直的流线在整个空间中被障碍物偏转。受变换光学和超材料的启发，近期的理论提出了流体隐形的概念，它能够恢复笔直的流线，就好像障碍物不存在一样。然而，这样一种隐形装置，与之前所有基于变换光学的器件类似，依赖于具有非均匀参数的复杂超材料，并且难以实现。在此，我们运用散射抵消理论，并报告一种无需超材料的流体流动隐形装置的实验实现。这种隐形装置是通过设计流体通道的几何形状来实现的，它有效地抵消了障碍物类似偶极子的散射。通过直接观察流体流动中恢复的笔直流线，证明了隐形效果。我们的工作为传统流体控制带来了新的思路，并可能在微流体装置中得到应用。
