(70cb) Dem Simulation of Fluidized Bed by Similarity Model (Similarity Conditions from Non-Dimensional Equations)

Discrete Element Method (DEM) is widely applied to simulate the phenomena in fluidized beds. The computational expense increase explosively as the number of particles becomes larger. This prevents DEM from being applied to simulations of real-scale fluidized beds. In order to overcome this problem, some kinds of methods have been proposed. A model particle method is one of the effective and available methods. In this method, real particles are replaced by model particles that have larger diameter than real particles. The computational expense is reduced effectively by use of the model particle method. When the model particle method is applied, some parameters of the system, such as gas viscosity or particle density, must be controlled so that so-called 'similarity conditions' are satisfied. In the present paper, the similarity conditions were derived from the dimensionless equations of motion. The velocity and the frequency of generation of bubbles were compared between calculations with the real particle (0.3 mm in diameter) and the model particle. The bubble motion with the real particle was well-reproduced by the model particle of the diameter up to 2 mm (approximately 7 times the real particle). Difference was observed in the bubble motion when the diameter of the model particle becomes larger than 3 mm.