移动网格与Level Set耦合方法在气-液两相流数值模拟中的应用

APPLICATION OF THE COUPLED LEVEL SET METHOD AND MOVINGMESH METHOD IN NUMERICAL SIMULATION OF GAS-LIQUID TWO-PHASE FLOWS NUMERICAL SIMULATION

本文采用自适应移动网格与Level Set函数相耦合的方法来实现气-液两相流的数值模拟与计算。作为自适应网格方法的一种,移动网格方法主要是为了解决发展方程的计算问题而设计的方法。文中给出了移动网格的生成方程,并针对方程的非线性,给出了一种半隐式的离散方法用于进行求解。本文将移动网格方法与Level Set方法相耦合,将控制流体运动的Navier-Stokes方程以及追踪相界面的Level Set方程转换到曲线坐标下,应用一套曲线坐标方程组来同时描述气、液两相流的运动规律,成功实现了对气-液两相流问题的数值模拟。通过对顶盖驱动流的计算以及对液滴沉降现象的模拟计算,验证了本文方法的可靠性。本文对常重力与微重力下两气泡融合的发展规律进行了数值模拟,通过分析对比,得到了重力对两气泡融合变形的影响规律。

A numerical method coupling the Level Set method with the moving-mesh method for numerical simulation of gas-liquid two-phase flow is introduced in this paper. Moving mesh method, as one of the adaptive mesh methods, is developed for resolving the computation problem of evolutionary equations. A generation equation of moving mesh is presented. Because of the non-linearity of the equations, a semi-implicit discretization is used to resolve this equation. Through coupling the level set method with the moving-mesh method, and transforming the N-S equations and the level set equation to the curvilinear coordinates, a numerical simulation model is built for the study of the gas-liquid two-phase flows. A numerical simulation of a gas-liquid two-phase flow has been successfully realized. Through simulating lid-driven cavity flow and water drop in the air, the methods in this paper is verified. The simulation of the coalescence of two bubbles under the gravity and microgravity conditions were carried out in this paper, and influence of gravity on the evolution of the coalescence of two bubbles are obtained through the analysis.