Development of an interface tracking algorithm for numerical simulation of stratified two-phase flow using a finite volume, pressure-based method

Two-phase and multi-phase flows are the common flow types in fluid mechanics engineering. Among the basic and applied problems of these flow types, stratified flow is the one that two immiscible fluids flow in vicinity of each other. In this type of flow, fluid properties (e.g. density, viscosity, and temperature) can be different at two sides of the interface of two fluids. The most challenging part of the numerical simulation of stratified flow is to determine the location of interface, accurately. In present work, an interface tracking algorithm is developed based on Arbitrary Lagrangian-Eulerian (ALE) approach using a cell-centered, pressure-based coupled solver. To validate this algorithm, analytical solution for stratified flow in presence of gravity is derived and then, the results of the numerical simulation of this flow are compared with analytical solution at various flow conditions. The results of the simulations show good accuracy of the algorithm despite using a nearly coarse and uniform grid. Temporal variations of interface profile toward the steady-state solution show that the more difference between fluids properties (especially dynamic viscosity), will results in larger traveling waves. Gravity effect studies also show that positive gravity will results in reduction of and negative gravity leads to increasing the thickness of the heavier fluid with respect to the zero gravity condition. However, the magnitude of variation in positive gravity is much more than negative gravity.