偏晶合金液-液相分离的格子玻尔兹曼方法模拟

本文建立了一个模拟在弥散相液滴的扩散长大、碰撞凝并和Ostwald熟化等因素的作用下偏晶合金液-液相分离过程的二维格子玻尔兹曼方法 (lattice Boltzmann method, LBM) 模型.该模型结合了Shan-Chen的两相流模型和Qin的介观粒子相互作用势模型的优点，并在LB演化方程中引入了反映相变的源项.应用该模型模拟研究了偏晶合金液-液相分离过程中单液滴的生长、两液滴的合并和多液滴的生长规律.结果表明在两液相区中第二相单个液滴的生长是一个通过扩散从非平衡态到平衡态过渡的过程.两液滴合并关键词：偏晶合金液-液相分离格子玻尔兹曼方法

Lattice Boltzmann modelling of liquid-liquid phase separation of monotectic alloys

A two-dimensional (2D) lattice Boltzmann method (LBM) model was developed to simulate liquid-liquid phase separation of monotectic alloys, which is controlled by the diffusive growth, the collisions and coagulations, and the Ostwald ripening of the minority liquid droplets. The present model combines the features of the multiphase flow model proposed by Shan-Chen and the mesoscopic interparticle potentials developed by Oin. In addition, a source term is introduced in the LB evolution equations to account for the phase transformation. The proposed LBM model was applied to simulate single droplet growth, coagulation of two droplets and multi-droplet growth during the liquid-liquid phase separation process of a monotectic alloy. The simulation shows that the single droplet growth in the two-liquid phase is controlled by diffusion and that the initial nonequilibrium composition approaches to equilibrium. The coagulation velocity of two droplets is influenced by surface tension, which is in accordance with the trend of the analytical prediction. It is found that the liquid-liquid phase separation process is obviously impacted by the collisions and coagulations and the Ostwald ripening of the droplets.