Abstract

A new simpler coarse-grain model (SCG) for analyzing particle behaviors under fluid flow in a dilute system, by using a discrete element method (DEM), was developed to reduce calculation load. In the SCG model, coarse-grained (CG) particles were enlarged from original particles in the same way as the existing coarse-grain model; however, the modeling concept differed from the other models. The SCG model focused on the acceleration by the fluid drag force, and the CG particles’ acceleration coincided with that of the original particles. Consequently, the model imposed only the following simple rule: the product of particle density and squared particle diameter is constant. Thus, the model had features that can be easily implemented in the DEM simulation to comprehend the modeled physical phenomenon. The model was validated by comparing the behaviors of the CG particles with the original particles in the uniform and the vortex flow fields. Moreover, the usability of the SCG model on simulating real dilute systems was confirmed by representing the particle behavior in a classifier. Therefore, the particle behavior in dilute particle-concentration systems would be analyzed more simply with the SCG model.

Highlights

  • This indicates that the simpler coarse-grain model (SCG) model can analyze the classification effect and the motion of the particles in the classifier, and that the SCG model could be applied to simulate a real dilute system that has a number of particles and different particle diameters

  • We developed the to analyze the particle behavior in the dilute particle-concentration systems by using ing to analyze the particle behavior in the dilute particle-concentration systems by using the particles moved in the same the discrete element method (DEM) simulation

  • In the SCG model, the CG particles moved in the same wayway and and speeds of the original particles in fluid flow by changing the particle density to follow speeds of the original particles in fluid flow by changing the CG particle density to follow ρp d =

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Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Coarse-grain models have been developed as an effective method to reduce the calculation load of the DEM simulation. Collision force is assumed to occur between two imaginary spheres, while fluid drag force is calculated by the summation of fluid drag forces acted on the original particles in one imaginary sphere. These three models indicated that the particle behavior in fluidized beds could be represented, and that the calculation load could be reduced, the particle behavior cannot be represented with sufficient accuracy. Most of the reports applied the coarse-grain models to complex powder phenomena, fundamental particle behavior when no collision occurs has hardly been validated. To confirm the usability of the SCG model for representing the particle behavior in an actual process, the SCG model is applied to represent the particle behavior in a classifier, and the behaviors of a number of CG particles are compared with the original particles

Simulation Method
SCG Model for Fluid Drag Force
Comparisons
Comparison of Particle Behavior in Classifier
Geometry
Conclusions
Findings
Figures A1 and
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