A new closure approximation based on the Cohen/Padé spring law and a novel method for its implementation

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• 作者：Abbas Sheikh
• 关键词：Brownian dynamics ; Closure equations ; FENE dumbbell fluids ; Oldroyd ; B fluid ; Shear flow ; Polymer kinetic theory
• 刊名：Rheologica Acta
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：56
• 期：2
• 页码：135-148
• 全文大小：
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Characterization and Evaluation of Materials; Polymer Sciences; Soft and Granular Matter, Complex Fluids and Microfluidics; Mechanical Engineering; Food Science;
• 出版者：Springer Berlin Heidelberg
• ISSN：1435-1528
• 卷排序：56

文摘

A new closure-approximated model based on the Cohen/Padé (CP) spring law is presented. Because it is inspired by the finitely extensible non-linear elastic Peterlin version (FENE-P), the model is titled CP-P. The rheological behaviors in simple and pressure-driven pipe shear flows in both the steady-state and time-dependent conditions are compared between the two models. To this end, a new approach based on the second moment Fokker–Planck equation instead of the Langevin equation is developed, which was confirmed by means of the existing analytical and stochastic data prior to its use. Application of this new approach is restricted to the closure approximated models but at a much less computational expense than the CONNFFESSIT-like simulations. In addition, the Brownian configuration field method is employed to make verification possible and more importantly, to shed light on the rheological performance of the CP model. According to the results, the CP-P model behaves similarly to the FENE-P model for the shear flows. The transient rheological behavior of the CP model is significantly different from that of the CP-P model, but both are the same in steady state.