Role of micellar entanglements on kinetics of shear banding flow formation
Role of micellar entanglements on kinetics of shear banding flow formation
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DOI：
10.1122/8.0000436
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发表时间：
2022-01
影响因子：
3.3
通讯作者：
Peter Rassolov;Hadi Mohammadigoushki
中科院分区：
文献类型：
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作者：
Peter Rassolov;Hadi Mohammadigoushki
研究了胶束纠缠数对Taylor-Couette流中剪切带流形成动力学的影响。在稳态剪切启动条件下，研究了三组蠕虫状胶束溶液，每组溶液具有相似的流体弹性和零剪切速率粘度，但具有不同的缠结密度。我们的实验表明，在流体弹性较低的情况下，在一定的纠缠密度范围内，瞬变剪切带状流的特征是形成瞬变反转流动。在此范围之外，没有观察到瞬时流动逆转。对于中等和高弹性组，在较小的纠缠密度下存在瞬变流动反转，而在较大的纠缠密度下消失。我们的分析表明，壁面滑移和弹性不稳定不会影响瞬变流动特性。我们发现胶束纠缠数、应力平台的宽度和瞬时流动逆转的程度之间存在关联。随着胶束纠缠数的增加，应力平台的宽度先增大，然后在较高的胶束纠缠数下，平台宽度减小。因此，我们假设瞬时流动反转通过应力平台的宽度与胶束纠缠数有关。
We investigate the effects of micellar entanglement number on the kinetics of shear banding flow formation in a Taylor–Couette flow. Three sets of wormlike micellar solutions, each set with a similar fluid elasticity and zero-shear-rate viscosity, but with varying entanglement densities, are studied under the startup of steady shear. Our experiments indicate that in the set with low fluid elasticity, the transient shear banding flow is characterized by the formation of a transient flow reversal in a range of entanglement densities. Outside of this range, the transient flow reversal is not observed. For the sets of medium and high elasticities, the transient flow reversals exist for relatively small entanglement densities and disappear for large entanglement densities. Our analysis shows that wall slip and elastic instabilities do not affect the transient flow feature. We identify a correlation between micellar entanglement number, the width of the stress plateau, and the extent of the transient flow reversal. As the micellar entanglement number increases, the width of the stress plateau first increases; then, at a higher micellar entanglement number, the plateau width decreases. Therefore, we hypothesize that the transient flow reversal is connected to the micellar entanglement number through the width of the stress plateau.