| Introduction: Although great progress has been made in modeling the fluidization of Geldart B and D particles and dilute gas-solid flow in gas-fluidized beds by standard Eulerian approach, researchers have shown that such approach fails to reproduce the hydrodynamic characteristics of Geldart A particles in gas-fluidized beds, a sub-grid scale model is necessary to consider the effect of the unresolved sub-grid scale structures on the constitutive relationships. However, the questions remain are why the standard Eulerian approach fails and how to establish the SGS model. Project aim: The objective of this research is to explore the underlying mechanics of the failure of standard Eulerian model in simulation of Geldart A particles in gas-fluidized beds. project approach The simulation methods used in this project are the two intermediate scale methods, i.e. standard Eulerian model and discrete particle model, in the multi-scale simulation framework of gas-solid flows (van der Hoef et al., 2008). Discrete particle model is able to capture the details of particle-particle and particle-wall interaction and is regarded as a reliable method to explore the nature of gas-fluidized beds. Standard Eulerian model treats both the fluid and solid phases as interpenetrating continua, the success or failure of such method is dominated by the constitutive laws used. Therefore, it is possible to study the nature of why standard Eulerian model fails to predict the hydrodynamics of Geldart A particles, through comparing the results obtained from the exactly same system using both methods. |
