Metachronal patterns by magnetically-programmable artificial cilia surfaces for low Reynolds number fluid transport and mixing.
Metachronal patterns by magnetically-programmable artificial cilia surfaces for low Reynolds number fluid transport and mixing.
复制标题
磁性可编程人工纤毛表面的异时性模式，用于低雷诺数流体传输和混合。
作者：
Rongjing Zhang;J. D. Toonder;P. Onck
运动纤毛可以在低雷诺数下产生净流体流动，因为它们的不对称运动和集体跳动的异时性。用人工纤毛模仿这一点可以在用于流体传输和混合的微流体装置中找到应用。在这里，我们研究了不同的磁编程人工纤毛的异时性跳动，其个体非往复运动和集体异时性跳动模式可以独立控制。我们使用有限元方法以完全耦合的方式解释磁力、纤毛变形和流体流动。模仿生物纤毛，我们研究受各种异时驱动模式影响的磁性纤毛，包括反波、辛波、反波和介电波。我们分析诱导的初级流动、次级流动和混合速率作为纤毛之间相位滞后的函数，并探索潜在的物理机制。我们的结果表明，相邻纤毛之间的屏蔽效应导致抗皱波的初级流动大于辛异时波。二次流可以用异时波的传播方向来充分解释。最后，我们表明，混合速率可以通过非电和非电异时性来强烈增强，从而产生大的速度梯度和涡流状流动模式。
Motile cilia can produce net fluid flows at low Reynolds number because of their asymmetric motion and metachrony of collective beating. Mimicking this with artificial cilia can find application in microfluidic devices for fluid transport and mixing. Here, we study the metachronal beating of nonidentical, magnetically-programmed artificial cilia whose individual non-reciprocal motion and collective metachronal beating pattern can be independently controlled. We use a finite element method that accounts for magnetic forces, cilia deformation and fluid flow in a fully coupled manner. Mimicking biological cilia, we study magnetic cilia subject to a full range of metachronal driving patterns, including antiplectic, symplectic, laeoplectic and diaplectic waves. We analyse the induced primary flow, secondary flow and mixing rate as a function of the phase lag between cilia and explore the underlying physical mechanism. Our results show that shielding effects between neighboring cilia lead to a primary flow that is larger for antiplectic than for symplectic metachronal waves. The secondary flow can be fully explained by the propagation direction of the metachronal wave. Finally, we show that the mixing rate can be strongly enhanced by laeoplectic and diaplectic metachrony resulting in large velocity gradients and vortex-like flow patterns.