State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an 710049, China.
Suzhou Academy of Xi'an Jiaotong University, Suzhou, Jiangsu 215123, China.
J Phys Chem Lett. 2021 Oct 21;12(41):10099-10105. doi: 10.1021/acs.jpclett.1c02795. Epub 2021 Oct 11.
Shear flows play critical roles in biological systems and technological applications and are achieved experimentally using moving parts. However, when the system size is reduced to micro- and nanoscale, fabrication of moving parts becomes exceedingly challenging. We demonstrate that a heterogeneous nanochannel composed of two parallel walls with different wetting behaviors can generate shear flow without moving parts. Molecular dynamics simulations show that shear flows can be formed inside such a nanochannel under a temperature gradient. The physical origin is that thermo-osmosis velocities with different rates and directions can be tuned by wetting behaviors. Our analysis reveals that thermo-osmosis is governed by surface excess enthalpy and nanoscale interfacial hydrodynamics. This finding provides an efficient method of generating controllable shear flows at micro- and nanoscale confinement. It also demonstrates the feasibility of using fluids to drive micromechanical elements via shear torques generated by harvesting energy from temperature differences.
剪切流在生物系统和技术应用中起着至关重要的作用，可以通过移动部件在实验中实现。然而，当系统尺寸缩小到微纳尺度时，制造移动部件变得极其困难。我们证明，由具有不同润湿性的两个平行壁组成的非均匀纳米通道可以在没有移动部件的情况下产生剪切流。分子动力学模拟表明，在温度梯度下可以在这样的纳米通道内形成剪切流。其物理起源是可以通过润湿性来调整不同速率和方向的热渗透速度。我们的分析表明，热渗透由表面过剩焓和纳米尺度界面流体动力学控制。这一发现为在微纳约束下产生可控剪切流提供了一种有效的方法。它还证明了可以通过从温差中收集能量产生剪切扭矩来利用流体驱动微机械元件的可行性。
