A geometrical mass control loop is proposed in this research to use in the level set method in order to simulation of multiphase flows with complex topologies of the interface and a case study is investigated using proposed scheme. In this regard oblique interaction and coalescence of bubbles in a liquid is investigated. The level set method is suffering from poor mass conservation in the case of severe changes of interface and complex topologies encountered in a wide range of problems which one of them is oblique coalescence of the bubbles. Despite the use of full re-initialization and reconstruction approach of the level set method as well as application of fine mesh, deviation of mass conservation of the method even becomes 100%. Therefore, simulation of such problems sometimes becomes impossible using this method. So in the geometric mass control loop, mass deviation in each time step is calculated and is compensated in the dispersed phase, which prevents the propagation of mass error entire the simulation. Efficiency of proposed geometrical mass control loop is verified by simulation of oblique interaction and coalescence of gas bubbles in a liquid. The governing equations are continuity and momentum equations which have been discretized using the finite volume method and the SIMPLE algorithm. The results outlined in the present study well agree with the existing experimental and numerical results. Results show that the maximum amount of mass dissipation was less than 4%. Therefore, the level set method with proposed geometric mass control loop could be used properly for the simulation of multiphase flows with sharp and high variations in the interface.

中文翻译：

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水平集方法中的几何质量控制方法，用于模拟具有复杂界面拓扑的多相流，案例研究：液体中气泡的倾斜聚结

本研究中提出了一种几何质量控制回路，用于水平集方法，以模拟具有复杂界面拓扑的多相流，并使用所提出的方案进行了案例研究。在这方面，研究了液体中气泡的倾斜相互作用和聚结。水平集方法在界面剧烈变化和复杂拓扑结构的情况下质量守恒性差，遇到了广泛的问题，其中之一是气泡的倾斜聚结。尽管使用了水平集方法的完全重新初始化和重建方法，并应用了细网格，但该方法的质量守恒偏差甚至达到了100%。因此，使用这种方法有时无法模拟此类问题。因此在几何质量控制回路中，计算每个时间步的质量偏差并在分散相中进行补偿，从而防止质量误差在整个模拟过程中传播。建议的几何质量控制回路的效率通过模拟液体中气泡的倾斜相互作用和聚结来验证。控制方程是使用有限体积法和 SIMPLE 算法离散化的连续性和动量方程。本研究中概述的结果与现有的实验和数值结果非常吻合。结果表明，最大质量耗散量小于4%。因此，提出的几何质量控制环的水平集方法可以适当地用于模拟界面剧烈变化的多相流。