Modelling the three-dimensional flow of a semi-dilute polymer solution in microfluidics-on the effect of aspect ratio
Modelling the three-dimensional flow of a semi-dilute polymer solution in microfluidics-on the effect of aspect ratio
复制标题
模拟微流体中半稀聚合物溶液的三维流动——纵横比的影响
DOI：
10.1007/s00397-009-0410-8
复制
发表时间：
2010
期刊：
影响因子：
2.3
通讯作者：
Omowunmi S
中科院分区：
文献类型：
--
作者：
Omowunmi S
聚合物溶液在微流体装置中的流动本质上是三维的，特别是在非线性流动状态下，并且经常导致甚至可能在宏观装置中不会遇到的流动现象。采用多模式的B-Thien-坦纳模型，对半稀聚氧化乙烯（PEO）溶液通过不同深度的8：1平面收缩微通道的流场进行了三维模拟，系统地研究了通道深宽比对流场的影响.详细量化了上游流动段的涡动力学和超压降。当展弦比从1变化到1/4时，对应于弹性数E1 = 36.3 ~ 48.3，观察到从凸角涡机制到唇涡机制的转变。数值结果表明，改变微流体通道的纵横比具有类似的效果，改变其他参数，如流体的性质，这影响弹性数。因此，我们的结果支持这样的观点，即涡的增长机制是由弹性数，这是固定的给定的流体和几何形状。该原理对设计具有广泛应用前景的新型微流控芯片具有重要意义。
The flow of polymer solutions in microfluidic devices is inherently three-dimensional, especially in the non-linear flow regime, and often results in flow phenomena that might not even be encountered in macro-devices. Using a multi-mode Phan-Thien–Tanner model, three-dimensional (3-D) simulations of a semi-dilute polyethylene oxide (PEO) solution through 8:1 planar contraction micro-channels with various depths have been carried out to systematically study the effect of the aspect ratio on the flow fields. Vortex dynamics in the upstream flow section and excess pressure drop are quantified in detail. A transition from a salient-corner vortex mechanism to a lip vortex mechanism is observed as the aspect ratio is varied from 1 to 1/4, which corresponds to the elasticity numbers El = 36.3 to 48.3. The numerical results show that varying the aspect ratio of microfluidic channels has similar effects to varying other parameters, such as fluid properties, which influence the elasticity number. Thus, our results support the view that vortex growth mechanism is determined by the elasticity number, which is fixed for a given fluid and geometry. The principle is of significance to the design of new microfluidic chips for a wide range of applications.