Manikantan Harishankar, Saintillan David
Department of Mechanical and Aerospace Engineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0411, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2015 Oct;92(4):041002. doi: 10.1103/PhysRevE.92.041002. Epub 2015 Oct 20.
An analytical expression for the fluctuation-rounded stretch-coil transition of semiflexible polymers in extensional flows is derived. The competition between elasticity and tension is known to cause a buckling instability in filaments placed near hyperbolic stagnation points and the effect of thermal fluctuations on this transition has yet to receive full quantitative treatment. Motivated by the findings of recent experiments as well as our simulations, we solve for the amplitude of the first buckled mode near the onset of the instability. This reveals a stochastic supercritical bifurcation, which is in excellent agreement with full numerical simulations.
推导了半柔性聚合物在拉伸流动中波动圆滑化的拉伸-卷曲转变的解析表达式。已知弹性和张力之间的竞争会导致放置在双曲线驻点附近的细丝出现屈曲不稳定性，而热波动对这种转变的影响尚未得到充分的定量处理。受近期实验结果以及我们的模拟结果的启发，我们求解了不稳定性开始时附近第一个屈曲模式的振幅。这揭示了一个随机超临界分岔，与全数值模拟结果非常吻合。
