Abstract Summary (Max 250 words)
This work adopts the Lattice Boltzmann Method (LBM) coupled with Large Eddy Simulation (LES) to conduct high-fidelity simulation of turbulent mixing and liquid-liquid dispersion dynamics in Rushton baffled stirred tanks, combining the Eulerian-Lagrangian approach and Discrete Phase Model (DPM) for droplet tracking. A D3Q19 multiple-relaxation-time LBM scheme is employed to solve the continuous phase flow field, with the immersed boundary method for accurate modeling of complex tank geometries including rotating impellers and baffles. To address the key challenge of Lagrangian time step dependence in traditional droplet breakage models, a probabilistic breakage approach is proposed, where breakage probability is proportional to the time step and breakage occurs when the probability exceeds a random 0–1 value. This model eliminates artificial breakage frequency distortion and accurately predicts the Sauter mean diameter and droplet size distribution. LBM simulations reveal detailed mixing characteristics: droplet trajectory tortuosity increases with impeller speed due to enhanced radial/axial circulations, peak droplet velocity locates in the impeller zone and shifts toward the tank wall at higher rotational speeds. The LBM framework enables precise capture of multi-scale mixing hydrodynamics, including turbulent energy dissipation and droplet motion, providing a reliable numerical tool for understanding and optimizing stirred tank mixing processes in chemical and process engineering.
