标题： 非等温条件下两同轴圆筒间聚合物熔体的多尺度模拟 显示英文标题

标题： Multiscale simulation of a polymer melt flow between two coaxial cylinders under nonisothermal conditions

摘要： 我们成功地将多尺度模拟（MSS）方法扩展到两个同轴圆筒之间的非等温高度纠缠聚合物熔体流动。 在多尺度模拟中，宏观流动系统通过速度梯度张量、应力张量和温度与多个微观系统相连。 在宏观层面上，除了动量平衡方程外，我们还考虑了能量平衡方程，其中热量生成不仅在温度分布中起重要作用，而且在流动轮廓中也起重要作用。 在微观层面上，采用双滑移链接模型来描述高度纠缠的聚合物。 为了将温度效应纳入微观系统，我们使用了滑移链接模型的时间-温度叠加规则，其中参数的温度依赖性未知；另一方面，在宏观方程中考虑温度效应的方法已经得到充分确立。 我们发现，扩展的多尺度模拟方法在揭示稳态和瞬态情况下非等温聚合物流动与由原始路径和滑移链接表示的聚合物链微观状态之间的关系方面非常有效。 还发现，基于温度依赖的蛇行时间的魏森伯格数是理解本研究中剪切速率范围内聚合物链变形程度的合适度量。 显示英文摘要

摘要： We successfully extend a multiscale simulation (MSS) method to nonisothermal well-entangled polymer melt flows between two coaxial cylinders. In the multiscale simulation, the macroscopic flow system is connected to a number of microscopic systems through the velocity gradient tensor, stress tensor and temperature. At the macroscopic level, in addition to the momentum balance equation, we consider the energy balance equation, where heat generation plays an important role not only in the temperature distribution but also in the flow profile. At the microscopic level, a dual slip-link model is employed for well-entangled polymers. To incorporate the temperature effect into the microscopic systems, we used the time-temperature superposition rule for the slip-link model, in which the temperature dependence of the parameters is not known; on the other hand, the way to take into account the temperature effect in the macroscopic equations has been well established. We find that the extended multiscale simulation method is quite effective in revealing the relation between nonisothermal polymeric flows for both steady and transient cases and the microscopic states of polymer chains expressed by primitive paths and slip-links. It is also found that the temperature-dependent reptation-time-based Weissenberg number is a suitable measure for understanding the extent of the polymer chain deformation in the range of the shear rate used in this study.