Microkinetic model and numerical simulations of particulate acoustic agglomeration
FAN Fengxian
XU Yue
Abstract：Objective Existing studies on acoustic particle agglomeration have predominantly focused on several research areas.Kinetic models for single particles were developed,and the particle entrainment velocity by acoustic waves was measured.The acoustic wake theory has been systematically elaborated,and particle interaction simulations under the acoustic wake effect were con-ducted.Studies have also simulated the microkinetics of particle agglomeration under the coupled influence of acoustic wake and mutual scattering effects.Significant attention has been given to the discrete element method(DEM)for acoustic agglomeration characterization that incorporates particle contact processes and related numerical simulations.Although these studies have pro-vided insights into the microkinetic behaviors of acoustic particle agglomeration,the particulate acoustic agglomeration process cannot be fully characterized.This limitation primarily arises from the accuracy constraints of the current modelling approaches.To address the deficiency in existing microkinetic models for acoustic agglomeration regarding the coupled effects of acoustic wake and mutual scattering,an improved microkinetic model for particulate acoustic agglomeration under multiple coupling mechanisms was constructed,greatly enhancing the accuracy in predicting the microkinetic behaviors of particles.
Methods The DEM was used to investigate the interaction between two particles of identical size in a standing wave acoustic field.The gas-phase velocity was modified under the coupled effects of acoustic wake and mutual scattering to ensure that the flow field at the particle surface satisfied the no-slip velocity boundary condition.Previous models superimposed the acoustic wave fluctuation velocity with the perturbation velocity induced by acoustic wake and mutual scattering to reproduce the multi-mechanism coupling effects.A comparative analysis was conducted between the experimental and the numerical simulation results obtained from both previous models and the improved particle acoustic agglomeration model under multiple coupling mechanisms.This validation confirmed the accuracy of the proposed model.Based on these findings,the influence of the par-ticles' initial positions on their acoustic agglomeration kinetic behaviors was further explored.
Results and Discussion The improved microkinetic model for particulate acoustic agglomeration under multiple coupling mecha-nisms enabled the prediction of particle collision time.It also fully reproduced the entire process of particle interactions observed in experiments within the acoustic field,involving particle approach,collision,acoustic agglomeration,and the subse-quent movement of the formed particle aggregates.In contrast,previous models exhibited unreliable predictions regarding the post-collision kinetic behaviors of particles.For particles initially located between two adjacent nodes in a standing-wave acous-tic field,the acoustic agglomeration time of particles varied symmetrically with their initial positions due to the symmetry of the acoustic wave fluctuation equation.The closer the particles' initial positions were to the antinodes,the stronger the attractive effect of the acoustic wake,and consequently,the shorter the acoustic agglomeration time.Particles with larger diameters had a broader range of initial positions from which acoustic agglomeration could occur and required shorter acoustic agglomeration time,indicating that larger particles were more prone to acoustic agglomeration.When the particles' initial positions were close to the nodes,the weak acoustic wake effect could not overcome the repulsive force caused by mutual scattering,thereby prevent-ing particle collision and acoustic agglomeration.
Conclusions In comparison with previous models,the improved DEM-based microkinetic model for particulate acoustic agglom-eration under multiple coupling mechanisms demonstrates superior accuracy in predicting kinetic behavior of particle acoustic agglomeration.This enhanced model plays a significant role in elucidating the microkinetic behaviors and underlying mecha-nisms of acoustic agglomeration processes.
Keywords：particle kineticsacoustic agglomerationdiscrete element methodgas-solid two-phase flow
Publication Date：2026-01-01
Online Publishing Date：2026-05-22(First online date of this platform, not the publication date of the document)
Pages：11( 33-43 )