Li Qing, Luo K H
Energy Technology Research Group, Faculty of Engineering and the Environment, University of Southampton, Southampton SO17 1BJ, United Kingdom.
Energy Technology Research Group, Faculty of Engineering and the Environment, University of Southampton, Southampton SO17 1BJ, United Kingdom and Department of Mechanical Engineering, University College London, University of London, Torrington Place, London WC1E 7JE, United Kingdom.
Phys Rev E Stat Nonlin Soft Matter Phys. 2013 Nov;88(5):053307. doi: 10.1103/PhysRevE.88.053307. Epub 2013 Nov 15.
In this paper, we aim to address an important issue about the pseudopotential lattice Boltzmann (LB) model, which has attracted much attention as a mesoscopic model for simulating interfacial dynamics of complex fluids, but suffers from the problem that the surface tension cannot be tuned independently of the density ratio. In the literature, a multirange potential was devised to adjust the surface tension [Sbragaglia et al., Phys. Rev. E 75, 026702 (2007)]. However, it was recently found that the density ratio of the system will be changed when the multirange potential is employed to adjust the surface tension. An alternative approach is therefore proposed in the present work. The basic strategy is to add a source term to the LB equation so as to tune the surface tension of the pseudopotential LB model. The proposed approach can guarantee that the adjustment of the surface tension does not affect the mechanical stability condition of the pseudopotential LB model, and thus provides a separate control of the surface tension and the density ratio. Meanwhile, it still retains the mesoscopic feature and the computational simplicity of the pseudopotential LB model. Numerical simulations are carried out for stationary droplets, capillary waves, and droplet splashing on a thin liquid film. The numerical results demonstrate that the proposed approach is capable of achieving a tunable surface tension over a very wide range and can keep the density ratio unchanged when adjusting the surface tension.
在本文中，我们旨在解决伪势格子玻尔兹曼（LB）模型的一个重要问题。该模型作为模拟复杂流体界面动力学的介观模型已引起广泛关注，但存在表面张力不能独立于密度比进行调节的问题。在文献中，已设计出一种多范围势来调节表面张力[Sbragaglia等人，《物理评论E》75，026702（2007）]。然而，最近发现当采用多范围势调节表面张力时，系统的密度比会发生变化。因此，本文提出了一种替代方法。基本策略是在LB方程中添加一个源项，以调节伪势LB模型的表面张力。所提出的方法可以保证表面张力的调节不会影响伪势LB模型的力学稳定性条件，从而实现表面张力和密度比的独立控制。同时，它仍然保留了伪势LB模型的介观特征和计算简便性。对静止液滴、毛细波以及液滴在薄液膜上的飞溅进行了数值模拟。数值结果表明，所提出的方法能够在很宽的范围内实现可调表面张力，并且在调节表面张力时能够保持密度比不变。
