基于分子动力学方法模拟聚合物稀溶液喷泉流动

Simulation of Fountain Flow Based on Molecular Dynamics Method

摘要: 本文基于分子动力学原理利用FENE哑铃模型对聚合物稀溶液流动前沿喷泉效应开展数值模拟。利用欧拉法求解力学模型在简单剪切流场下的构型方程和哑铃分子的位形方程，获取示踪流线和流动前沿哑铃分布，计算应力场，分析流变演化规律，研究温度和剪切速率等参数对该模型的影响，分析FENE哑铃分子模型模拟喷泉效应的有效性。结果表明，在喷泉效应的作用下，随着剪切速率的升高哑铃分子的伸展变大，流动前沿聚合物应力会出现应力过冲，随后趋于稳定的复杂变化，哑铃分子沿喷泉流线取向。

Abstract: In this paper, numerical simulations of the fountain effect on the flow front of polymer dilute solu-tions are carried out based on molecular dynamics principles and the FENE dumbbell model. The Euler method is used to solve the constitutive equations of the mechanical model for the simple shear flow field and the dislocation equations of the dumbbell molecules, and subsequently obtain the tracer flow lines and the dumbbell distribution of the flow front. The results are used to calcu-late the stress field, analyze the rheological evolution law, study the effect of temperature and shear rate and other parameters on the model and analyze the effectiveness of the FENE dumbbell molec-ular model for the fountain effect. The study shows that due to the fountain effect, the dumbbell molecules stretch more with increasing shear rate, the polymer stress at the flow front will show a complex change of stress overshoot and then stabilize, and the dumbbell molecules are oriented along the fountain flow line.