Tung Chih-Kuan, Ardon Florencia, Roy Anubhab, Koch Donald L, Suarez Susan S, Wu Mingming
Department of Biological and Environmental Engineering, Cornell University, Ithaca, New York 14853, USA.
Department of Biomedical Sciences, Cornell University, Ithaca, New York 14853, USA.
Phys Rev Lett. 2015 Mar 13;114(10):108102. doi: 10.1103/PhysRevLett.114.108102.
We demonstrate that upstream swimming of sperm emerges via an orientation disorder-order transition. The order parameter, the average orientation of the sperm head against the flow, follows a 0.5 power law with the deviation from the critical flow shear rate (γ-γ_{c}). This transition is successfully explained by a hydrodynamic bifurcation theory, which extends the sperm upstream swimming to a broad class of near surface microswimmers that possess front-back asymmetry and circular motion.
我们证明精子的上游游动通过取向无序-有序转变出现。序参量，即精子头部相对于水流的平均取向，随着与临界流剪切率（γ-γc）的偏差遵循0.5次幂律。这种转变通过流体动力学分岔理论得到了成功解释，该理论将精子的上游游动扩展到了一类广泛的具有前后不对称和圆周运动的近表面微型游动体。
