Developing an Interface Tracking Coupled Solver for Solving two Phase Flow Fields at Low Reynolds Numbers in foam-extend Platform

Document Type : Article

Authors

1 Department of Aerospace Engineering, Faculty of New Sciences and Technologies, University of Tehran

2 Department of Aerospace Engineering, Faculty of New Science and Technology, University of Tehran, Tehran, Iran

Abstract

In present study, for the first time, a finite volume coupled solver is developed for simultaneous numerical solution of two-phase incompressible fluid flow equations at low Reynolds numbers and the equation for the interface position by applying interface boundary conditions using foam-extend platform. The studied flows with interface and mesh motion are considered to be laminar and in the rage of Reynolds numbers less than 100. The Foam-extend is a fork of OpenFOAM, an open-source object-oriented C++ library for computational continuum mechanics. This solver is based on the interface tracking algorithm, which is developed using an innovative technique called zero-thickness cell. This technique causes the distance effect to be removed for the cell adjacent to the interface and the interface is modeled with zero thickness. The main advantage of present coupled solver compared to the previously developed solvers is that in this solver, all the equations governing both phases are coupled with each other by cells adjacent to the interface and with an equation for the interface position. All the governing equations and the equation for the interface position are assembled in a linear system of equations and simultaneously solved. In fact, unlike the usual segregated procedure of solving two-phase flows, where the phases are solved with lagged value boundary conditions, in the present solver, the phases are solved simultaneously with the interface conditions in implicit manner and a same block matrix system. The movement of the interface has been done separately and, in another step, using kinematic condition. Computational performance of coupled solver will be evaluated by solving the equations of two-phase fluid flow inside a channel and on a backward facing step. At beginning, a preliminary investigation has been done for the case where both phases are completely independent and decoupled. Matching the interface with the streamlines as well as reasonable and justifiable movement of the surface has been observed from the physical point. Also, the damping of the numerical oscillations generated on the interface and changing the flow variables will be investigated. The present results are in excellent agreement with other results reported in the literature.

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Sharif Journal of Mechanical Engineering

Articles in Press, Accepted Manuscript
Available Online from 20 June 2024

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