Numerical Study on Coarse Grain Modeling of the DEM for Industrial Scale Gas-Solid Flow Systems

The Discrete Element Method (DEM) is widely used in various numerical simulations related to granular media. The DEM is a Lagrangian approach where individual particle is calculated based on the Newton’s second law of motion. Therefore, the DEM enables us to investigate the granular flow characteristics at the particle level. On the other side, the DEM has a difficulty to be applied in large-scale powder systems because the calculation cost becomes too expensive when the number of particles is huge. To solve this issue, we have developed a coarse grain modeling as a large scale model of the DEM. The coarse grain particle represents a group of original particles. The coarse grain model was used in typical gas-solid and solid-liquid two phase flows so far, where the particle size was relatively large, namely, cohesive force did not act between the solid particles. In the present study, the coarse grain model is evolved to simulate fine particles by considering the interparticle van der Waals force. The adequacy of the coarse grain model is proved by comparing the simulation results of original particle system. Through this study, the coarse grain model is shown to simulate the cohesive particle behavior precisely.