Lattice Boltzmann modeling of multiphase flows at large density ratio with an improved pseudopotential model.
Lattice Boltzmann modeling of multiphase flows at large density ratio with an improved pseudopotential model.
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DOI：
10.1103/physreve.87.053301
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发表时间：
2012-11
期刊：
影响因子：
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通讯作者：
Qing Li;Kai H. Luo;X. Li
中科院分区：
文献类型：
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作者：
Qing Li;Kai H. Luo;X. Li
伪势多相晶格玻尔兹曼（LB）模型由于其概念简单和计算效率高，自提出以来一直受到广泛关注。在这项工作中，我们的目标是扩展伪势LB模型，以模拟大密度比和相对高雷诺数的多相流。首先，根据我们最近的工作[Q]。李，罗康辉，李晓军，物理学家。Rev. E . 86, 016709(2012)]，提出了一种改进的多松弛时间伪势LB模型强迫方案，以实现模型的热力学一致性和大密度比。其次，通过研究Carnahan-Starling状态方程中参数a的影响，我们发现界面厚度近似与1/√a成正比。采用较小的a可以使界面厚度变宽，从而可以减少杂散电流，提高伪势模型在大密度比下的数值稳定性。此外，还发现在伪势模型中，通过增大气液两相的运动粘度比可以获得较低的液体粘度。通过对静止液滴和振荡液滴的模拟，对改进的伪势LB模型进行了数值验证。利用改进的模型和上述处理方法，在密度比大于500、雷诺数为40 ~ 1000的条件下，对液滴溅落在薄液膜上进行了数值模拟。正确地再现了液滴飞溅的动力学过程，并发现预测的扩散半径符合文献报道的幂律。
Owing to its conceptual simplicity and computational efficiency, the pseudopotential multiphase lattice Boltzmann (LB) model has attracted significant attention since its emergence. In this work, we aim to extend the pseudopotential LB model to simulate multiphase flows at large density ratio and relatively high Reynolds number. First, based on our recent work [Q. Li, K. H. Luo, and X. J. Li, Phys. Rev. E 86, 016709 (2012)], an improved forcing scheme is proposed for the multiple-relaxation-time pseudopotential LB model in order to achieve thermodynamic consistency and large density ratio in the model. Next, through investigating the effects of the parameter a in the Carnahan-Starling equation of state, we find that the interface thickness is approximately proportional to 1/√a. Using a smaller a will lead to a wider interface thickness, which can reduce the spurious currents and enhance the numerical stability of the pseudopotential model at large density ratio. Furthermore, it is found that a lower liquid viscosity can be gained in the pseudopotential model by increasing the kinematic viscosity ratio between the vapor and liquid phases. The improved pseudopotential LB model is numerically validated via the simulations of stationary droplet and droplet oscillation. Using the improved model as well as the above treatments, numerical simulations of droplet splashing on a thin liquid film are conducted at a density ratio in excess of 500 with Reynolds numbers ranging from 40 to 1000. The dynamics of droplet splashing is correctly reproduced and the predicted spread radius is found to obey the power law reported in the literature.