New Property Averaging Scheme for Volume of Fluid Method for Two-Phase Flows With Large Viscosity Ratios

Abstract

To predict liquid–gas two-phase flow, accurate tracking of the evolving liquid–gas interface is required. Volume-of-fluid (VoF) method has been used for computationally modeling such flows where a single set of governing equations are solved for both phases along with an advection equation for the volume fraction. Properties in each cell are determined by a linear weighted average of the properties of the two fluids based on the phase fraction. While the method predicts water–air flows well, the predictions tend to deviate significantly from experiments for liquids with high viscosity. A new property averaging technique is proposed, which is shown to provide accurate results for high viscosity liquids. Computational predictions using open-source VoF solver inter-foam and the proposed method are compared with experimental data for multiple two-phase applications. Four different problems, viz., suspended drop, jet breakup, drop impact on thin films, and on liquid pools, are considered to extensively validate the new method. Data for aqueous solutions of propylene and ethylene glycol are used to cover a range of surface tension (72–36 mN/m) and viscosities (1–40 mPa·s). For all cases, the modified VoF solver is observed to perform significantly better than the original VoF method. It reduces spurious currents in simulations of a drop suspended in the air. For the cases of a drop impacting on a pool and during drop generation from liquid jets, the time progression of the surface tension governed dynamics is improved from the slower estimate of the inter-Foam solver.