Large‐scale discrete element modeling in a fluidized bed

Abstract

SUMMARYThe discrete element method (DEM) is widely used in calculating powder systems. The DEM makes it possible to determine the complicated phenomena related to particle flowability. However, DEM has a fatal problem, which is that the number of calculated particles is restricted due to excessive calculation costs. Consequently, we have developed a large-scale model of the DEM, which is called the coarse grain model. The coarse grain particle represents a group of the original particles. Therefore, a large-scale DEM simulation can be performed using an extremely small number of the calculated particles. In our previous studies, the coarse grain model was applied in gas-solid and solid-liquid flow systems. It is anticipated that the coarse grain model will be used in various powder systems. In the current study, the coarse grain model has been applied to a two-dimensional bubbling fluidized bed. The adequacy of the coarse grain model was proved by a comparison with the original particle behavior. The simulation results obtained using the coarse grain model showed good agreement with the results for the original system. Moreover, the calculation speed with the coarse grain model was shown to be much faster than the calculation speed of the original model.

Three-dimensional simulation of gas–solid–liquid flows using the DEM–VOF method

“…The governing equations are solved with a classical finite-volume method. The spatial discretization and solution methodology based on the fractional-step method are similar to those in Sakai et al (2010).…”

Discrete element simulation for the evaluation of solid mixing in an industrial blender

“…This methodology is referred to as the DEM-CFD method [14]. The DEM-CFD method has been used to model a variety of dense gas-solid flows such as a bubbling fluidized bed [15][16][17][18][19]and pneumatic conveying [20,21]. Very recently, new Lagrangian-Lagrangian approaches have been developed to simulate solid-liquid flows involving free surfaces, where the DEM is coupled with a Lagrangian CFD approach such as the smoothed particle hydrodynamics (SPH) method [22] or the moving-particle semi-implicit (MPS) method [23].…”

Rockslide and Impulse Wave Modelling in the Vajont Reservoir by DEM-CFD Analyses

“…thousands of billions of grains). To overcome this problem, the coarse grain model has been proposed (Sakai and Koshizuka 2009;Sakai et al 2010Sakai et al , 2012). In this model, a coarse particle can represent a collection of real fine particles.…”