Department of Physics, Durham University, Science Laboratories, South Road, Durham DH1 3LE, United Kingdom.
CCMT, Department of Physics, Indian Institute of Science, Bangalore 560 012, India.
Phys Rev Lett. 2015 Mar 6;114(9):098302. doi: 10.1103/PhysRevLett.114.098302. Epub 2015 Mar 5.
A paradigm for internally driven matter is the active nematic liquid crystal, whereby the equations of a conventional nematic are supplemented by a minimal active stress that violates time-reversal symmetry. In practice, active fluids may have not only liquid-crystalline but also viscoelastic polymer degrees of freedom. Here we explore the resulting interplay by coupling an active nematic to a minimal model of polymer rheology. We find that adding a polymer can greatly increase the complexity of spontaneous flow, but can also have calming effects, thereby increasing the net throughput of spontaneous flow along a pipe (a "drag-reduction" effect). Remarkably, active turbulence can also arise after switching on activity in a sufficiently soft elastomeric solid.
一个内部驱动物质的范例是主动向列液晶，通过这种液晶，常规向列方程通过最小主动应力得到补充，而这种主动应力违反了时间反演对称性。在实践中，活性流体不仅可能具有液晶，而且可能具有粘弹性聚合物自由度。在这里，我们通过将主动向列与聚合物流变学的最小模型耦合来探索由此产生的相互作用。我们发现，添加聚合物可以大大增加自发流动的复杂性，但也可以产生镇静作用，从而增加沿管道的自发流动的总吞吐量（“减阻”效果）。值得注意的是，在足够软的弹性固体中开启活性后，也可能出现主动湍流。
