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Microswimmers near corrugated, periodic surfaces
Soft Matter ( IF 2.9 ) Pub Date : 2021-2-25 , DOI: 10.1039/d0sm01782e
Christina Kurzthaler 1 , Howard A Stone
Affiliation  

We explore hydrodynamic interactions between microswimmers and corrugated, or rough, surfaces, as found often in biological systems and microfluidic devices. Using the Lorentz reciprocal theorem for viscous flows we derive exact expressions for the roughness-induced velocities up to first order in the surface-height fluctuations and provide solutions for the translational and angular velocities valid for arbitrary surface shapes. We apply our theoretical predictions to elucidate the impact of a periodic, wavy surface on the velocities of microswimmers modeled in terms of a superposition of Stokes singularities. Our findings, valid in the framework of a far-field analysis, show that the roughness-induced velocities vary non-monotonically with the wavelength of the surface. For wavelengths comparable to the swimmer-surface distance a pusher can experience a repulsive contribution due to the reflection of flow fields at the edge of a surface cavity, which decreases the overall attraction to the wall.

中文翻译:

靠近波纹状周期性表面的微型游泳器

我们探索微型游泳器和波纹或粗糙表面之间的流体动力学相互作用,这在生物系统和微流体装置中经常出现。使用粘性流的洛伦兹倒数定理,我们推导出表面高度波动中粗糙度引起的速度的精确表达式,并提供适用于任意表面形状的平移速度和角速度的解决方案。我们应用理论预测来阐明周期性波状表面对根据斯托克斯奇点叠加建模的微型游泳器速度的影响。我们的研究结果在远场分析框架中有效,表明粗糙度引起的速度随表面波长非单调变化。对于与游泳者表面距离相当的波长,由于表面空腔边缘处流场的反射,推动器可能会经历排斥作用,这会降低对壁的整体吸引力。
更新日期:2021-02-25
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