Yu Y, Li Q, Huang R Z
School of Energy Science and Engineering, Central South University, Changsha 410083, China.
Phys Rev E. 2021 Jul;104(1-2):015303. doi: 10.1103/PhysRevE.104.015303.
The free-energy lattice Boltzmann (LB) method is a multiphase LB approach based on the thermodynamic theory. Compared with traditional free-energy LB models, which employ a nonideal thermodynamic pressure tensor, the chemical-potential-based free-energy LB model has attracted much attention in recent years as it avoids computing the thermodynamic pressure tensor and its divergence. In this paper, we propose an improved wetting boundary condition for the chemical-potential-based free-energy LB model. Different from the original wetting boundary condition in the literature, the improved wetting boundary condition utilizes a surface chemical potential that is compatible with the chemical potential of the fluid domain. Accordingly, the thermodynamic consistency of the chemical-potential-based free-energy LB model can be retained by the improved wetting boundary condition. Numerical simulations are performed for droplets resting on flat and cylindrical surfaces with different contact angles. The numerical results show that the improved wetting boundary condition yields more reasonable results and the maximum spurious velocities are found to be smaller by 2 ∼ 3 orders of magnitude than those produced by the original wetting boundary condition.
自由能格子玻尔兹曼（LB）方法是一种基于热力学理论的多相LB方法。与采用非理想热力学压力张量的传统自由能LB模型相比，基于化学势的自由能LB模型近年来备受关注，因为它避免了计算热力学压力张量及其散度。在本文中，我们为基于化学势的自由能LB模型提出了一种改进的润湿边界条件。与文献中原来的润湿边界条件不同，改进的润湿边界条件利用了与流体域化学势兼容的表面化学势。因此，改进的润湿边界条件可以保持基于化学势的自由能LB模型的热力学一致性。对静置在具有不同接触角的平面和圆柱面上的液滴进行了数值模拟。数值结果表明，改进的润湿边界条件产生的结果更合理，并且发现最大虚假速度比原来的润湿边界条件产生的速度小2至3个数量级。
