47 巻 (2010) 1 号 p. 17-25
Discrete Element Method (DEM) is widely used in many powder systems. The DEM makes possible to figure out the complicated phenomena related to particle flowability. On the other side, the DEM has a fatal problem, that is, the number of calculated particles is restricted due to the excessive calculation cost. Thereat, we have developed a large scale model of the DEM which is called coarse grain model. The coarse grain represents a group of the original particles so that a large-scale DEM simulation can be performed by using extremely small number of the calculated particles. In our previous studies, the coarse grain model was used in not only gas-solid flow simulations like a pneumatic conveying system but also a fundamental study of solid liquid flows. The coarse grain model is expected to be used in various powder systems. Therefore, in the current study, the coarse grain model was applied to a two-dimensional bubbling fluidized bed. The results by the coarse grain model were in good agreement with that of the original system. The coarse grain model was shown to be available in the bubbling fluidized bed. Moreover, it is exhibited that the calculation speed with the coarse grain model is much faster than that of the original one.