Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China and Department of Chemistry, University of Cambridge, CB21EW Cambridge, UK.
Department of Chemistry, University of Cambridge, CB21EW Cambridge, UK.
Soft Matter. 2020 Apr 15;16(15):3621-3627. doi: 10.1039/c9sm02053e.
Gradients in temperature, concentration or electrostatic potential cannot exert forces on a bulk fluid; they can, however, exert forces on a fluid in a microscopic boundary layer surrounding a (nano)colloidal solute, resulting in so-called phoretic flow. Here we present a simulation study of phoretic flow around a spherical colloid held fixed in a concentration gradient. We show that the resulting flow velocity depends non-monotonically on the strength of the colloid-fluid interaction. The reason for this non-monotonic dependence is that solute particles are effectively trapped in a shell around the colloid and cannot contribute to diffusio-phoresis. We also observe that the flow depends sensitively on the anisotropy of solute-colloid interaction.
温度、浓度或静电势的梯度不能对整体流体施加力；然而，它们可以对（纳米）胶体溶质周围的微观边界层中的流体施加力，导致所谓的泳流。在这里，我们对固定在浓度梯度中的球形胶体周围的泳流进行了模拟研究。我们表明，由此产生的流速与胶体-流体相互作用的强度呈非单调关系。这种非单调关系的原因是，溶质粒子实际上被困在胶体周围的壳层中，无法对扩散泳起作用。我们还观察到，这种流动对溶质-胶体相互作用的各向异性敏感。
