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

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.

Analysis and comparison of boundary condition variants in the free‐surface lattice Boltzmann method

“…The LBM collision (1) and streaming (2) is performed in all interface and liquid cells. As opposed to Körner et al, 1 following other authors, 19,28,30 the gravitational force is not weighted with an interface cell's fill level in the LBM collision in this article.…”

“…Bogner 19 and Thies 20 have argued that it is not sufficient to only reconstruct missing PDFs, but it has to be ensured that at least three PDFs are reconstructed (OM3) with the free-surface boundary condition (18). Otherwise, the macroscopic boundary condition at the free interface ( 17) would be underdetermined.…”

“…In the final variant, only missing but at least three PDFs are reconstructed. 19,20 The force-balance computations show that neither of these four variants generally balances the forces at the interface. In five different numerical experiments, the boundary condition variants are then compared in different applications.…”

Numerical Studies of Disperse Three-Phase Fluid Flows

“…Other authors have focused on the interaction of a single bubble with point particles. Those include [17], who captured the bubble by a phase-field method and [18], who used an LBM method. Refs.…”

Numerical Simulations on Gas-Liquid-Particle Flows in Three-Phase Slurry Reactors under gravity variation

“…Li and Zhong [21] studied the gas-liquid-solid three-phase ow in bubble columns using a three-dimensional timedependent Eulerian-Eulerian-Eulerian three-uid approach. Bogner et al [22] performed a direct numerical simulation of liquid-gas-solid ows with a free surface Lattice Boltzmann method. All the above models are based on Eulerian-Eulerian approach.…”