Coarse-grained DEM-CFD simulation of a pilot-scale gaz-fluidized bed

Abstract

Abstract: Recent studies point CGDEM (Coarse-Grained Discrete Element Method) as a valuable tool to circumvent the cost of original DEM (Discrete Element Method) simulations for large-scale industrial applications such as fluidized beds. In this approach, cost savings are ensured by decreasing the number of particles in the domain, while increasing their size. In the present work, CGDEMLES (Large-Eddy Simulation) numerical simulations are carried out on a 3D cylindrical pilot-scale fluidized bed in the bubbling regime and gathering 9.6M Geldart B-type particles. A macroscopic analysis is performed and allow observing the effects of coarse-graining on the bed behavior qualitatively and quantitatively. Among them, a global homogeneization of the fluidized region, characterized by higher bed surfaces, lower solid velocity and solid fraction gradients, is reported, along with a drop in the bubble population. These effects are observed to intensify as the coarse-graining factor increases. Some of the reported issues can be alleviated by employing additional mechanisms from the literature, aiming at dissipating the extra amount of energy inherently present in coarse-grained systems. However, these are barely sufficient to retrieve DEM results with the smallest coarsegraining factor tested.Communication présentée lors du congrès international tenu conjointement par Canadian Society for Mechanical Engineering (CSME) et Computational Fluid Dynamics Society of Canada (CFD Canada), à l’Université de Sherbrooke (Québec), du 28 au 31 mai 2023