# A volume-of-fluid method for interface-resolved simulations of phase-changing two-fluid flows

## TL;DR

This paper introduces a novel volume-of-fluid method for accurately simulating phase-changing two-fluid flows with evaporation, ensuring mass conservation and validated through extensive benchmarks in 2D and 3D.

## Contribution

The paper presents a new interface-resolved VoF method with a divergence-free velocity extension for phase change, compatible with algebraic and geometric VoF approaches.

## Key findings

- Excellent mass conservation demonstrated in benchmarks
- Method performs well in 2D and 3D simulations
- Validated against multiple benchmark cases

## Abstract

We present a numerical method for interface-resolved simulations of evaporating two-fluid flows based on the volume-of-fluid (VoF) method. The method has been implemented in an efficient FFT-based two-fluid Navier-Stokes solver, using an algebraic VoF method for the interface representation, and extended with the transport equations of thermal energy and vaporized liquid mass for the single-component evaporating liquid in an inert gas. The conservation of vaporizing liquid and computation of the interfacial mass flux are performed with the aid of a reconstructed signed-distance field, which enables the use of well-established methods for phase change solvers based on level-set methods. The interface velocity is computed with a novel approach that ensures accurate mass conservation, by constructing a divergence-free extension of the liquid velocity field onto the entire domain. The resulting approach does not depend on the type of interface reconstruction (i.e.\ can be employed in both algebraic and geometrical VoF methods). We extensively verified and validated the overall method against several benchmark cases, and demonstrated its excellent mass conservation and good overall performance for simulating evaporating two-fluid flows in two and three dimensions.