论文标题
径向热毛细血管流动的方位角不稳定，围绕被困在水上界面的热珠
Azimuthal instability of the radial thermocapillary flow around a hot bead trapped at the water-air interface
论文作者
论文摘要
我们研究了由水 - 空气界面部分润湿的激光加热微粒驱动的径向热毛细管流。特别关注随着越来越加热的热球周围对流流动模式的演变。在低激光功率的情况下，流动形态几乎是轴对称。增加P会导致对称性破裂，反向旋转涡流对的发作。界面处的边界条件接近低-P机制中的无滑动，在高-P机制中的涡流对之间无应力。这些观察结果强烈支持以下观点：表面活性杂质不可避免地在水面上吸附在形成弹性层的水面上。涡旋对的发作是对离心力流动层的层反应中流体动力不稳定性的标志。有趣的是，我们的研究为设计能够通过液体界面上的涡旋生成来实现高速自我的活性胶体为设计铺平了道路。
We investigate the radial thermocapillary flow driven by a laser-heated microbead in partial wetting at the water-air interface. Particular attention is paid to the evolution of the convective flow patterns surrounding the hot sphere as the latter is increasingly heated. The flow morphology is nearly axisymmetric at low laser power P. Increasing P leads to symmetry breaking with the onset of counter-rotating vortex pairs. The boundary condition at the interface, close to no-slip in the low-P regime, turns about stress-free between the vortex pairs in the high-P regime. These observations strongly support the view that surface-active impurities are inevitably adsorbed on the water surface where they form an elastic layer. The onset of vortex pairs is the signature of a hydrodynamic instability in the layer response to the centrifugal forced flow. Interestingly, our study paves the way for the design of active colloids able to achieve high-speed self-propulsion via vortex pair generation at a liquid interface.
