固気混相流における離散要素法の粗視化手法の開発

Abstract

Discrete element method is an effective approach for evaluating the particle behavior in granular flows, whereas it is seldom used in investigating the design and the operation in industries. This is due to the fact that the number of particles is restricted by the limit of computer memories. Consequently the original discrete element method is difficult to be applied to the real-scale systems, where a large number of particles are dealt with. In this study, a new discrete element modeling for real-scale particle systems is proposed where a coarse grain represents a crowd of original particles. The new model, which is called coarse grain model, can be applied in general gas-solid flows by considering not only the drag force but also the contact force in the original particle system. In the present study, the coarse grain model is applied to a two-dimensional fluidized bed. The change in particle bed height, the bubble size and the minimum fluidization velocity are compared between the coarse grain model and the original particle system. The coarse grain simulation results show good agreement with those of the original particle system.