Lattice Boltzmann simulations of 3D crystal growth: Numerical schemes for a phase-field model with anti-trapping current

TL;DR

This paper develops a lattice-Boltzmann scheme for simulating 3D alloy solidification with dendrite growth, incorporating anisotropy and anti-trapping effects, validated against finite-difference methods and capable of producing diverse crystal shapes.

Contribution

It introduces a modified LB scheme for phase-field alloy solidification, accounting for anisotropy and anti-trapping, with validation and shape versatility.

Findings

Validated against finite-difference simulations.

Successfully modeled various crystal shapes.

Demonstrated effectiveness of anisotropy functions.

Abstract

A lattice-Boltzmann (LB) scheme, based on the Bhatnagar-Gross-Krook (BGK) collision rules is developed for a phase-field model of alloy solidification in order to simulate the growth of dendrites. The solidification of a binary alloy is considered, taking into account diffusive transport of heat and solute, as well as the anisotropy of the solid-liquid interfacial free energy. The anisotropic terms in the phase-field evolution equation, the phenomenological anti-trapping current (introduced in the solute evolution equation to avoid spurious solute trapping), and the variation of the solute diffusion coefficient between phases, make it necessary to modify the equilibrium distribution functions of the LB scheme with respect to the one used in the standard method for the solution of advection-diffusion equations. The effects of grid anisotropy are removed by using the lattices D3Q15 and D3Q19 instead of D3Q7. The method is validated by direct comparison of the simulation results with a numerical code that uses the finite-difference method. Simulations are also carried out for two different anisotropy functions in order to demonstrate the capability of the method to generate various crystal shapes.