Bui Cuong Mai, Ho Anh-Ngoc Tran, Nguyen Xuan Bao
The University of Danang-University of Technology and Education, 48 Cao Thang, Da Nang 550000, Vietnam.
Polymers (Basel). 2022 Jun 9;14(12):2330. doi: 10.3390/polym14122330.
In this work, a numerical study of polymer flow behaviors in a lid-driven cavity, which is inspired by the coating process, at a broad range of Oldroyd numbers (0≤Od≤50), is carried out. The Reynolds number is height-based and kept at Re=0.001. The fluid investigated is of Carbopol gel possessing yield stress and shear-thinning properties. To express rheological characteristics, the Herschel-Bulkley model cooperated with Papanastasiou's regularization scheme is utilized. Results show that the polymer flow characteristics, i.e., velocity, viscosity, and vortex distributions, are considerably influenced by viscoplastic behaviors. Additionally, there exist solid-like regions which can be of either moving rigid or static dead types in the flow patterns; they become greater and tend to merge together to construct larger ones when Od increases. Furthermore, various polymer flow aspects in different cavity configurations are discussed and analyzed; the cavity width/aspect ratio and skewed angle are found to have significant impacts on the vortex structures and the formation of solid-like regions. Moreover, results for the critical aspect ratio at which the static dead zone is broken into two parts and the characteristic height of this zone are also reported in detail.
在这项工作中，我们对受涂层工艺启发的顶盖驱动方腔内聚合物流动行为进行了数值研究，研究范围涵盖了广泛的奥尔德罗伊德数（0≤Od≤50）。雷诺数基于高度确定，并保持在Re = 0.001。所研究的流体是具有屈服应力和剪切变稀特性的卡波姆凝胶。为了表达流变特性，采用了与帕帕纳斯塔西乌正则化方案相结合的赫谢尔 - 布克利模型。结果表明，聚合物的流动特性，即速度、粘度和涡旋分布，受粘塑性行为的影响很大。此外，在流动模式中存在类固体区域，它们可以是移动刚性类型或静态停滞类型；当奥尔德罗伊德数增加时，它们会变得更大并倾向于合并在一起形成更大的区域。此外，还讨论和分析了不同腔配置下聚合物流动的各个方面；发现腔宽/纵横比和倾斜角度对涡旋结构和类固体区域的形成有显著影响。此外，还详细报道了静态停滞区分为两部分时的临界纵横比以及该区域的特征高度的结果。
