A new kinetic model for multiphase flow was presented under the framework of the discrete Boltzmann method (DBM). Significantly different from the previous DBM, a bottom-up approach was adopted in this model. The effects of molecular size and repulsion potential were described by the Enskog collision model; the attraction potential was obtained through the mean-field approximation method. The molecular interactions, which result in the non-ideal equation of state and surface tension, were directly introduced as an external force term. Several typical benchmark problems, including Couette flow, two-phase coexistence curve, the Laplace law, phase separation, and the collision of two droplets, were simulated to verify the model. Especially, for two types of droplet collisions, the strengths of two non-equilibrium effects, \(\bar{D}^{\ast}_{2}\) and \(\bar{D}^{\ast}_{3}\), defined through the second and third order non-conserved kinetic moments of (f − f^eq), are comparatively investigated, where f (f^eq) is the (equilibrium) distribution function. It is interesting to find that during the collision process, \(\bar{D}^{\ast}_{2}\) is always significantly larger than \(\bar{D}^{\ast}_{3},\bar{D}^{\ast}_{2}\) can be used to identify the different stages of the collision process and to distinguish different types of collisions. The modeling method can be directly extended to a higher-order model for the case where the non-equilibrium effect is strong, and the linear constitutive law of viscous stress is no longer valid.

在离散玻尔兹曼方法（DBM）的框架下，提出了一种新的多相流动力学模型。与以前的DBM显着不同，此模型采用了自下而上的方法。Enskog碰撞模型描述了分子大小和排斥力的影响。通过平均场近似法获得了吸引力。分子相互作用（导致状态和表面张力的非理想方程式）直接作为外力项引入。仿真了一些典型的基准问题，包括Couette流，两相共存曲线，拉普拉斯定律，相分离和两个液滴的碰撞，以验证模型。特别是对于两种液滴碰撞，两种非平衡效应的强度\（\ bar {D} ^ {\ ast} _ {2} \）和\（\ bar {D} ^ {\ ast} _ {3} \），是通过二阶和三阶非守恒定律定义的对（f - f ^eq）的进行比较研究，其中f（f ^eq）是（平衡）分布函数。有趣的是，在碰撞过程中，\（\ bar {D} ^ {\ ast} _ {2} \）总是比\（\ bar {D} ^ {\ ast} _ {3}大得多，\ bar {D} ^ {\ ast} _ {2} \）可以用来识别碰撞过程的不同阶段并区分不同类型的碰撞。对于非平衡效应很强且粘性应力的线性本构律不再有效的情况，可以将建模方法直接扩展到高阶模型。