Lattice Boltzmann modeling of contact angle and its hysteresis in two-phase flow with large viscosity difference
Lattice Boltzmann modeling of contact angle and its hysteresis in two-phase flow with large viscosity difference
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大粘度差两相流接触角及其滞后的格子玻尔兹曼模型
DOI：
10.1103/physreve.92.033306
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发表时间：
2015-09-11
影响因子：
2.4
通讯作者：
Zhang, Yonghao
中科院分区：
文献类型：
--
作者：
Liu, Haihu;Ju, Yaping;Zhang, Yonghao
接触角滞后现象是自然界和各种工业过程中普遍存在的重要物理现象，但由于建模复杂，现有的多相流模拟中没有考虑其影响。在这项工作中，一个多相格子玻尔兹曼方法（LBM）的开发来模拟的接触线动力学与考虑接触角滞后的广泛的运动粘度比。在该方法中，不混溶的两相流描述的颜色流体模型，其中采用多松弛时间碰撞算子，以增加数值稳定性和抑制非物理的寄生电流在接触线。使用Ding和Spelt [Ding和Spelt，J.Fluid Mech.599，341（2008）]提出的策略引入接触角滞后，并且强制几何润湿边界条件以获得期望的接触角。该方法首先通过模拟理想（光滑）表面上的静态接触角和动态毛细侵入过程来验证。然后，它被用来模拟一个非理想（非均匀）表面上的液滴的动态行为受到简单的剪切流。当液滴由于滞后作用而保持钉扎在表面上时，液滴的稳定界面形状定量地与以前的数值结果吻合得很好。四个典型的运动模式的接触点，在最近的一项研究中观察到的，定性再现不同的前进和后退接触角。发现粘度比对液滴的变形、破碎和滞后行为有显著影响。最后，将该方法推广应用于半理想半非理想T形微流控接头中液滴破碎的数值模拟。由于接触角滞后，液滴在非理想分支通道中不对称地分裂成两个子液滴，其中较小的一个子液滴在两个分支通道中的行为明显不同。此外，它被发现，随着粘度比的降低，接触角滞后加强，导致更早的液滴破碎和破碎前的液滴可以达到的最大长度的减少。这些模拟结果表明，本多相LBM可以是Ba等人[Phys.Rev.E88，043306（2013）]用于模拟接触角滞后的有用替代物，并且它可以以更高的计算效率容易地实现。
Contact angle hysteresis is an important physical phenomenon omnipresent in nature and various industrial processes, but its effects are not considered in many existing multiphase flow simulations due to modeling complexity. In this work, a multiphase lattice Boltzmann method (LBM) is developed to simulate the contact-line dynamics with consideration of the contact angle hysteresis for a broad range of kinematic viscosity ratios. In this method, the immiscible two-phase flow is described by a color-fluid model, in which the multiple-relaxation-time collision operator is adopted to increase numerical stability and suppress unphysical spurious currents at the contact line. The contact angle hysteresis is introduced using the strategy proposed by Ding and Spelt [Ding and Spelt, J. Fluid Mech. 599, 341 (2008)], and the geometrical wetting boundary condition is enforced to obtain the desired contact angle. This method is first validated by simulations of static contact angle and dynamic capillary intrusion process on ideal (smooth) surfaces. It is then used to simulate the dynamic behavior of a droplet on a nonideal (inhomogeneous) surface subject to a simple shear flow. When the droplet remains pinned on the surface due to hysteresis, the steady interface shapes of the droplet quantitatively agree well with the previous numerical results. Four typical motion modes of contact points, as observed in a recent study, are qualitatively reproduced with varying advancing and receding contact angles. The viscosity ratio is found to have a notable impact on the droplet deformation, breakup, and hysteresis behavior. Finally, this method is extended to simulate the droplet breakup in amicrofluidic T junction, with one half of the wall surface ideal and the other half nonideal. Due to the contact angle hysteresis, the droplet asymmetrically breaks up into two daughter droplets with the smaller one in the nonideal branch channel, and the behavior of daughter droplets is significantly different in both branch channels. Also, it is found that the contact angle hysteresis is strengthened with decreasing the viscosity ratio, leading to an earlier droplet breakup and a decrease in the maximum length that the droplet can reach before the breakup. These simulation results manifest that the present multiphase LBM can be a useful substitute to Ba et al. [Phys. Rev. E 88, 043306 (2013)] for modeling the contact angle hysteresis, and it can be easily implemented with higher computational efficiency.