Departamento de Engenharia Química, CEFT, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal.
Soft Matter. 2018 Feb 21;14(8):1344-1354. doi: 10.1039/c7sm01106g.
We experimentally investigate the dynamics of viscoelastic fluid flows in cross-slot microgeometries under creeping flow conditions. We focus on the unsteady flow regime observed at high Weissenberg numbers (Wi) with the purpose of understanding the underlying flow signature of elastic turbulence. The effects of the device aspect ratio and fluid rheology on the unsteady flow state are investigated. Visualization of the flow patterns and time-resolved micro-particle image velocimetry were carried out to study the fluid flow behavior for a wide range of Weissenberg numbers. A periodic flow behavior is observed at low Weissenberg numbers followed by a more complex dynamics as Wi increases, eventually leading to the onset of elastic turbulence for very high Weissenberg numbers.
我们在蠕动流条件下实验研究了横缝微几何中粘弹性流体流动的动力学。我们关注在高威森伯格数（Wi）下观察到的非定常流态，目的是了解弹性湍流的潜在流动特征。研究了器件纵横比和流体流变学对非定常流态的影响。通过可视化流型和时间分辨微粒子图像测速法，研究了广泛的威森伯格数下的流体流动行为。在低威森伯格数下观察到周期性流动行为，随着 Wi 的增加，流动行为变得更加复杂，最终在非常高的威森伯格数下导致弹性湍流的发生。
