Can phoretic particles swim in two dimensions?
Can phoretic particles swim in two dimensions?
复制标题
泳动粒子可以二维游泳吗？
作者：
David Sondak;Cory E. Hawley;Siyu Heng;Rebecca Vinsonhaler;E. Lauga;Jean
人工泳动粒子利用化学物种（自扩散泳动）或电荷和电流（自电泳）中的自生梯度游动。这些粒子可用于研究活性物质中集体运动的物理学，并可能在生物工程中有很好的应用前景。在自扩散电泳的情况下，经典的物理模型依赖于扩散方程的稳定解，从该稳定解可以导出化学梯度、电泳流和最终的游泳速度。出于对薄膜和约束下的盘形粒子，我们检查扩展到两个维度。由于二维扩散方程缺少具有正确边界条件的稳态，因此必须使用拉普拉斯变换来研究问题的长时间行为并确定游泳速度。对于固定的化学通量的颗粒表面上，我们发现，游泳速度最终总是随时间的推移而衰减。在有限的Péclet数的情况下，我们解决了完整的对流扩散方程数值，并表明，这种衰减可以避免移动到未消耗的反应物的区域的粒子。有限平流，从而正规化的二维泳问题。
Artificial phoretic particles swim using self-generated gradients in chemical species (self-diffusiophoresis) or charges and currents (self-electrophoresis). These particles can be used to study the physics of collective motion in active matter and might have promising applications in bioengineering. In the case of self-diffusiophoresis, the classical physical model relies on a steady solution of the diffusion equation, from which chemical gradients, phoretic flows, and ultimately the swimming velocity may be derived. Motivated by disk-shaped particles in thin films and under confinement, we examine the extension to two dimensions. Because the two-dimensional diffusion equation lacks a steady state with the correct boundary conditions, Laplace transforms must be used to study the long-time behavior of the problem and determine the swimming velocity. For fixed chemical fluxes on the particle surface, we find that the swimming velocity ultimately always decays logarithmically in time. In the case of finite Péclet numbers, we solve the full advection-diffusion equation numerically and show that this decay can be avoided by the particle moving to regions of unconsumed reactant. Finite advection thus regularizes the two-dimensional phoretic problem.