Direct simulation of liquid-gas-solid flow with a free surface lattice Boltzmann method

TL;DR

This paper introduces a scalable, fully parallel lattice Boltzmann method for direct numerical simulation of liquid-gas-solid flows, enabling detailed studies of bubble-particle interactions at large scales.

Contribution

It presents a novel, computationally feasible approach for simulating bubble-particle interactions with high resolution on supercomputers.

Findings

Simulations of over 100,000 particles are now feasible.

Resolved simulations differ significantly from unresolved models.

The method accurately captures flow structures in bubble-particle systems.

Abstract

Direct numerical simulation of liquid-gas-solid flows is uncommon due to the considerable computational cost. As the grid spacing is determined by the smallest involved length scale, large grid sizes become necessary -- in particular if the bubble-particle aspect ratio is on the order of 10 or larger. Hence, it arises the question of both feasibility and reasonability. In this paper, we present a fully parallel, scalable method for direct numerical simulation of bubble-particle interaction at a size ratio of 1-2 orders of magnitude that makes simulations feasible on currently available super-computing resources. With the presented approach, simulations of bubbles in suspension columns consisting of more than $100\,000$ fully resolved particles become possible. Furthermore, we demonstrate the significance of particle-resolved simulations by comparison to previous unresolved solutions. The results indicate that fully-resolved direct numerical simulation is indeed necessary to predict the flow structure of bubble-particle interaction problems correctly.