Phase-field modeling of dendritic growth with gas bubbles in the solidification of binary alloys

TL;DR

This paper develops a comprehensive phase-field model for dendritic growth in binary alloy solidification that includes gas bubbles, fluid flow, and complex interactions, validated through lattice Boltzmann simulations.

Contribution

The paper introduces a novel phase-field model that integrates gas bubbles, dendritic growth, and fluid flow with modifications for improved accuracy, matching classical models under specific conditions.

Findings

Model accurately captures dendritic growth with gas bubbles.

The model successfully simulates complex gas-liquid-solid interactions.

Good agreement with known behaviors in test simulations.

Abstract

In this work, a phase-field model is developed for the dendritic growth with gas bubbles in the solidification of binary alloys. In this model, a total free energy for the complex gas-liquid-dendrite system is proposed through considering the interactions of gas bubbles, liquid melt and solid dendrites, and it can reduce to the energy for gas-liquid flows in the region far from the solid phase, while degenerate to the energy for thermosolutal dendritic growth when the gas bubble disappears. The governing equations are usually obtained by minimizing the total free energy, but here some modifications are made to improve the capacity of the conservative phase-field equation for gas bubbles and convection-diffusion equation for solute transfer. Additionally, through the asymptotic analysis of the thin-interface limit, the present general phase-field model for alloy solidification can match the corresponding free boundary problem, and it is identical to the commonly used models under a specific choice of model parameters. Furthermore, to describe the fluid flow, the incompressible Navier-Stokes equations are adopted in the entire domain including gas, liquid, and solid regions, where the fluid-structure interaction is considered by a simple diffuse-interface method. To test the present phase-field model, the lattice Boltzmann method is used to study several problems of gas-liquid flows, dendritic growth as well as the solidification in presence of gas bubbles, and a good performance of the present model for such complex problems is observed.