Use of compromise-based local porosities for coarse grid DEM simulation of bubbling fluidized bed with large particles

In discrete element method (DEM) for simulations of gas-solid fluidized beds, coarse grid calculation can lead to excessive smoothing of local porosities for correlating drag on individual particles. This article tries to calculate local porosities with consideration of the heterogeneous particle distribution within a coarse grid. The compromise-based local porosity (CLP) model is set up and incorporated into coarse grid DEM simulations of gas-solid fluidized beds with large particles. Simulated bubble size and shape are in good agreement with experimental results. Various complex bubbling phenomena are described such as bubble eruption, bubble rupture and bubble coalescence. The fluctuations of solid volume fraction, relative pressure and bed layer height simulated at the fine-tuned parameters are in general agreement with the experimental data. These results indicate that the proposed CLP model is suitable to characterize distinct heterogeneities within coarse grids. (C) 2012 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.