Cluster granular temperature and rotational characteristic analysis of a binary mixture of particles in a gas-solid riser by mutative Smagorinsky constant SGS model

In this work, a gas-solid two-phase riser was analyzed using a discrete hard sphere particle model (DPM) for the solid phase and an improved sub-grid scale stress (SGS) model using the large eddy simulation (LES) method applied for the gas phase. A binary mixture of small and large particles was used in the simulation. Simulation results were compared with experimental data by Mathiesen et al. and showed good agreement A new parameter, cluster granular temperature, was proposed to analyze the particle macro-scale energy fluctuation. Various drag models, restitution coefficients and superficial gas velocities were applied to find out the influence on particle behaviors. It is found that the simulation by the mutative Smagorinsky constant model has advantages over invariant Smagorinsky constant model. The drag models and the restitution coefficients affect the particle movement and cluster granular temperature to some extent. The superficial gas velocity has a great effect on cluster granular temperature, especially for large particles. The distributions of rotational particle characteristics, such as rotational velocity and rotational cluster granular temperature, were specifically influenced by different SGS methods. (C) 2015 Elsevier B.V. All rights reserved.