论文标题
胶束纠缠密度在剪切带流的动力学上的作用
Role of Micellar Entanglement Density on Kinetics of Shear Banding Flow Formation
论文作者
论文摘要
我们研究了胶束纠缠数对泰勒 - 库特流动中剪切带状形成动力学的影响。在稳定的剪切启动下，研究了三组类似蠕虫的胶束溶液，每种胶片溶液都具有相似的流体弹性和零剪切速率的粘度，但具有变化的纠缠密度。我们的实验表明，在具有低流体弹性的集合中，瞬态剪切带流的特征在于形成在一系列纠缠密度中的瞬态流动逆转。在此范围之外，未观察到瞬态流动逆转。对于中等和高弹性的集合，存在瞬态流动逆转，以实现相对较小的纠缠密度，并且消失了大纠缠密度。我们的分析表明，壁滑和弹性不稳定性不会影响瞬态流量特征。我们确定了胶束纠缠数量，应力平台的宽度与瞬态流动逆转的程度之间的相关性。随着胶束纠缠数量的增加，应力高原的宽度首先增加，然后在较高的胶束纠缠数量下，高原宽度减小。因此，我们假设瞬态流动逆转通过应力平台的宽度连接到胶束纠缠数。
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 start-up of steady shear. Our experiments indicate that in the set with the 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, 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.
