Controlling bubble coalescence in metallic foams: A simple phase field-based approach
Controlling bubble coalescence in metallic foams: A simple phase field-based approach
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DOI：
10.1016/j.commatsci.2019.109437
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发表时间：
2020-02-15
影响因子：
3.3
通讯作者：
Varnik, Fathollah
中科院分区：
文献类型：
--
作者：
Vakili, Samad;Steinbach, Ingo;Varnik, Fathollah
相场方法被用作开发严格质量守恒但简单的两相流模拟模型的基础。该模型旨在应用于金属泡沫结构演化的研究。在这方面，关键问题是与并发过程（例如由于流体运动导致的重新排列）相比，控制气泡合并的速率。在本模型中，这是通过将界面能调整为自由参数来实现的。该模型经过多项基准测试的验证。首先，针对不同的界面能值，通过杨拉普拉斯定律研究了二维气泡的稳定性。然后，模拟两个气泡的合并，直到系统达到圆形平衡。为了解决当前模型形成泡沫结构的主要能力，针对不同的界面能值模拟气泡聚结，以减慢合并过程。在存在旋转流的情况下重复这些模拟，以强调这样一个事实：与气泡相对运动相比，该模型可以抑制聚结过程。此外，由于密度被视为“从属于”给定相所占据的体积的辅助变量，因此本模型允许实现任意大的液气密度比。该属性通过对 rho(l)/rho g = 10, 000 的系统进行仿真来证明。
The phase-field method is used as a basis to develop a strictly mass conserving, yet simple, model for simulation of two-phase flow. The model is aimed to be applied for the study of structure evolution in metallic foams. In this regard, the critical issue is to control the rate of bubble coalescence compared to concurrent processes such as their rearrangement due to fluid motion. In the present model, this is achieved by tuning the interface energy as a free parameter. The model is validated by a number of benchmark tests. First, stability of a two dimensional bubble is investigated by the Young-Laplace law for different values of the interface energy. Then, the coalescence of two bubbles is simulated until the system reaches equilibrium with a circular shape. To address the major capability of the present model for the formation of foam structure, the bubble coalescence is simulated for various values of interface energy in order to slow down the merging process. These simulations are repeated in the presence of a rotational flow to highlight the fact that the model allows to suppress the coalescence process compared to the motion of bubbles relative to each other. Moreover, since density is treated as an auxiliary variable "slaved" to the volume occupied by a given phase, the present model allows realization of arbitrarily large liquid-gas density ratios. This property is demonstrated by simulation of a system with rho(l)/rho g = 10, 000.