Simulated polymer stretch in a turbulent flow using Brownian dynamics
Simulated polymer stretch in a turbulent flow using Brownian dynamics
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DOI：
10.1017/s0022112004008250
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发表时间：
2004-04
影响因子：
3.7
通讯作者：
V. Terrapon;Y. Dubief;P. Moin;E. Shaqfeh;S. Lele
中科院分区：
文献类型：
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作者：
V. Terrapon;Y. Dubief;P. Moin;E. Shaqfeh;S. Lele
我们通过布朗动力学模拟研究了聚合物在湍流中的减阻现象。研究了在牛顿湍流通道流动中大量聚合物单链沿其运动轨迹的动力学。特别地，使用具有真实参数的FENE、FENE- p和多模FENE模型来研究聚合物的拉伸机理。一种拓扑学方法被应用于表征流动拉伸聚合物的能力。使用条件统计发现，在中等Weissenberg数Wi下，拉伸到其最大可拉伸性的很大一部分的聚合物经历了强烈的双轴拉伸流动。当Wi增加时，其他流动类型可以拉伸聚合物，但少数高度拉伸的分子平均再次经历双轴拉伸流动。此外，在准流向涡旋附近的近壁区域，主要是在强双轴拉伸流动区域，发现了高度延伸的聚合物。
We examine the phenomenon of polymer drag reduction in a turbulent flow through Brownian dynamics simulations. The dynamics of a large number of single polymer chains along their trajectories is investigated in a Newtonian turbulent channel flow. In particular, the FENE, FENE-P and multimode FENE models with realistic parameters are used to investigate the mechanisms of polymer stretching. A topological methodology is applied to characterize the ability of the flow to stretch the polymers. It is found using conditional statistics that at moderate Weissenberg number Wi the polymers, that are stretched to a large fraction of their maximum extensibility, have experienced a strong biaxial extensional flow. When Wi is increased other flow types can stretch the polymers but the few highly extended molecules again have, on average, experienced a biaxial extensional flow. Moreover, highly extended polymers are found in the near-wall regions around the quasi-streamwise vortices, essentially in regions of strong biaxial extensional flow.