Trouilloud Renaud, Yu Tony S, Hosoi A E, Lauga Eric
Hatsopoulos Microfluids Laboratory, Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA.
Phys Rev Lett. 2008 Jul 25;101(4):048102. doi: 10.1103/PhysRevLett.101.048102. Epub 2008 Jul 24.
Reciprocal movement cannot be used for locomotion at low Reynolds number in an infinite fluid or near a rigid surface. Here we show that this limitation is relaxed for a body performing reciprocal motions near a deformable interface. Using physical arguments and scaling relationships, we show that the nonlinearities arising from reciprocal flow-induced interfacial deformation rectify the periodic motion of the swimmer, leading to locomotion. Such a strategy can be used to move toward, away from, and parallel to any deformable interface as long as the length scales involved are smaller than intrinsic scales, which we identify. A macroscale experiment of flapping motion near a free surface illustrates this new result.
在无限流体中或靠近刚性表面时，往复运动在低雷诺数下不能用于移动。在此我们表明，对于在可变形界面附近进行往复运动的物体，这一限制会有所放宽。通过物理论证和尺度关系，我们表明由往复流动引起的界面变形所产生的非线性会使游泳者的周期性运动整流，从而实现移动。只要所涉及的长度尺度小于我们所确定的固有尺度，这种策略就可用于朝着、远离或平行于任何可变形界面移动。在自由表面附近进行拍动运动的宏观实验说明了这一新结果。
