Wang Heping, Zang Duyang, Li Xiaoguang, Geng Xingguo
Functional Soft Matter & Materials Group, Key Laboratory of Space Applied Physics and Chemistry of Ministry of Education, School of Science, Northwestern Polytechnical University, 710129, Xi'an, China.
Eur Phys J E Soft Matter. 2017 Dec 27;40(12):115. doi: 10.1140/epje/i2017-11605-6.
This paper presents an exploration of the phase separation behavior and pattern formation in a binary fluid with temperature-dependent viscosity via a coupled lattice Boltzmann method (LBM). By introducing a viscosity-temperature relation into the LBM, the coupling effects of the viscosity-temperature coefficient [Formula: see text] , initial viscosity [Formula: see text] and thermal diffusion coefficient [Formula: see text] , on the phase separation were successfully described. The calculated results indicated that an increase in initial viscosity and viscosity-temperature coefficient, or a decrease in the thermal diffusion coefficient, can lead to the orientation of isotropic growth fronts over a wide range of viscosity. The results showed that droplet-type phase structures and lamellar phase structures with domain orientation parallel or perpendicular to the walls can be obtained in equilibrium by controlling the initial viscosity, thermal diffusivity, and the viscosity-temperature coefficient. Furthermore, the dataset was rearranged for growth kinetics of domain growth and thermal diffusion fronts in a plot by the spherically averaged structure factor and the ratio of separated and continuous phases. The analysis revealed two different temporal regimes: spinodal decomposition and domain growth stages, which further quantified the coupled effects of temperature and viscosity on the evolution of temperature-dependent phase separation. These numerical results provide guidance for setting optimum temperature ranges to obtain expected phase separation structures for systems with temperature-dependent viscosity.
本文通过耦合格子玻尔兹曼方法（LBM）对具有温度依赖性粘度的二元流体中的相分离行为和图案形成进行了探索。通过将粘度 - 温度关系引入LBM，成功描述了粘度 - 温度系数[公式：见原文]、初始粘度[公式：见原文]和热扩散系数[公式：见原文]对相分离的耦合效应。计算结果表明，初始粘度和粘度 - 温度系数的增加，或热扩散系数的降低，可导致在很宽的粘度范围内各向同性生长前沿的取向。结果表明，通过控制初始粘度、热扩散率和粘度 - 温度系数，可以在平衡状态下获得液滴型相结构以及畴取向平行或垂直于壁面的层状相结构。此外，通过球平均结构因子以及分离相和连续相的比例，对数据进行重新排列以绘制畴生长和热扩散前沿的生长动力学曲线。分析揭示了两个不同的时间阶段：亚稳分解和畴生长阶段，这进一步量化了温度和粘度对温度依赖性相分离演化的耦合效应。这些数值结果为设定最佳温度范围提供了指导，以便为具有温度依赖性粘度的系统获得预期的相分离结构。
