LMFD Wiki

Particle-fluid two-phase flows (such as gas-solid and liquid-solid flows), frequently encountered in chemical reactors and separation devices, are almost always unstable, and complex spatio-temporal patterns are observed ubiquitously. One can usually observe structures at different length scales and time scales - micro, meso and macro scales - and they influence the mixing, mass transfer and heat transfer processes. Earlier studies of these systems were mainly focused on experimental investigations including measurement of macroscopic hydrodynamic behavior and the development of some corresponding correlations. In recent decades, to quantitatively understand the complex hydrodynamics of particle-fluid two-phase flows, the computational fluid dynamics approach is adopted in many cases, and a lot of numerical methods in the hydrodynamic modeling and simulation of particle-fluid two-phase flows have been proposed at different levels, such as two-fluid model (TFM), discrete particle simulation (DPS), and direct numerical simulation (DNS) . However, in the traditional computational fluid dynamics (CFD), the fluid motion with suspended solids is commonly governed by the volume-averaged Navier-Stokes equations or their simplified forms, and those equations are solved based on implicit/semi-implicit schemes no matter by Fluent, OpenFOAM, MFIX, or in-house codes. An implicit/semi-implicit solver solves iteratively all the discretized equations simultaneously, and most of the computational algorithms involved in it suffer from a less computational efficiency and a lower parallel efficiency. Therefore, it is a grand challenge in fast simulation of large-scale industrial systems if these equations for fluid flows are solved based on implicit/semi-implicit schemes. As a smoothed alternative to lattice gas automata (LGA), lattice Boltzmann method (LBM) is an efficient second-order flow solver capable of solving various systems for hydrodynamics owing to its explicit solution of particle distribution functions, algorithmic simplicity, natural parallelism and flexibility in boundary treatment. Therefore, the objective of this project is to develop a lattice Boltzmann based numerical framework for solving particle-fluid two-phase flows.