Capillary flow simulation with the phase-field-based lattice Boltzmann solver

TL;DR

This paper presents an advanced phase-field lattice Boltzmann solver for simulating capillary flows, accurately capturing complex flow patterns and pressure fields in multiphase systems with high fidelity.

Contribution

It introduces an optimized wettability and friction model into the LB framework, enabling precise simulation of static and dynamic multiphase flows in complex geometries.

Findings

Results align with theoretical predictions and experimental data.

The solver accurately reproduces pressure fields in multiphase flows.

Benchmark tests demonstrate robustness across various flow scenarios.

Abstract

The phase-field-based lattice Boltzmann (LB) model has been developed to perform high fidelity multiphase flow simulations. Its ability to accurately handle high density ratio and surface tension effects is expected to be beneficial for capillary flow simulation, leading to accurate reproduction of flow patterns such as slug flow, droplet flow, and film flow. This is critical in many engineering cases because the flow patterns significantly affect the velocity and pressure fields. In this study, on top of the LB models based on the conservative Allen-Cahn equation and the volumetric boundary conditions for the complex geometries, an optimized wettability and friction model are implemented. With these models, we conducted a set of benchmark test cases, including static and dynamic multiphase flow scenarios such as the droplet on the curved surfaces, water-filling channel for the Lucas-Washburn law, and the critical pressure in the three-dimensional channel, an air-driven multiphase flow in the experiments. In all of these cases, the solver produces results that are consistent with both theory and experiment, even with respect to the pressure field accuracy, which has often been overlooked in many previous studies.