Beech Jason P, Ström Oskar E, Turato Enrico, Tegenfeldt Jonas O
Division of Solid State Physics, Department of Physics, Lund University, Nano-Lund, Lund University PO Box 118 SE-221 00 Lund Sweden
RSC Adv. 2023 Oct 27;13(45):31497-31506. doi: 10.1039/d3ra06565k. eCollection 2023 Oct 26.
Solutions of macromolecules exhibit viscoelastic properties and unlike Newtonian fluids, they may break time-reversal symmetry at low Reynolds numbers resulting in elastic turbulence. Furthermore, under some conditions, instead of the chaotic turbulence, the result is large-scale waves in the form of cyclic spatial and temporal concentration variations, as has been shown for macromolecular DNA flowing in microfluidic pillar arrays. We here demonstrate how altering the symmetry of the individual pillars can be used to influence the symmetry of these waves. We control the extent of instabilities in viscoelastic flow by leveraging the effects of the symmetry of the pillars on the waves, demonstrating suppressed viscoelastic fluctuations with relevance for transport and sorting applications, or conversely opening up for enhanced viscoelasticity-mediated mixing. The onset of waves, which changes flow resistance, occurs at different Deborah numbers for flow in different directions through the array of triangular pillars, thus breaking the symmetry of the flow resistance along the device, opening up for using the occurrence of the waves to construct a fluidic diode.
大分子溶液表现出粘弹性特性，与牛顿流体不同，它们在低雷诺数下可能会打破时间反演对称性，从而导致弹性湍流。此外，在某些条件下，结果不是混沌湍流，而是以周期性空间和时间浓度变化形式出现的大规模波，正如在微流体柱阵列中流动的大分子DNA所显示的那样。我们在此展示了如何通过改变单个柱的对称性来影响这些波的对称性。我们利用柱的对称性对波的影响来控制粘弹性流动中的不稳定性程度，证明了抑制粘弹性波动与传输和分选应用相关，或者相反地促进了粘弹性介导的混合。波的出现会改变流动阻力，对于通过三角形柱阵列在不同方向流动的情况，波在不同的德博拉数下出现，从而打破了沿装置的流动阻力对称性，为利用波的出现构建流体二极管开辟了道路。
