(213a) Development of CFD-DEM Coupling Model for Particles-Liquid-Gas Flow

Particles-liquid-gas flow can be encountered in many environmental phenomena such as debris flow and riverbed erosion as well as many industrial applications including powder dispersion in a stirred tank and liquid imbibition in powders during a wet granulation process. The flow can be extremely complex due to the interactions between the phases, e.g. surface tension / capillary forces, wetting of particles surface and momentum exchanges. In the present work, a novel meso-scopic coupling model of CFD and DEM is developed which takes into account these interactions. The Diffuse Interface (DI) method is used to capture liquid and gas phases in CFD whilst DEM is used to track the movement of particles. Smooth mapping of particle-scale quantities to continuous fields, e.g. particle solid fraction, is achieved by using the diffusion-based coarse graining [1,2] so that the numerical cell size can be chosen independently of the particle size, which can be critical to treat the interfacial phenomena properly. Several simulation case studies are performed to show the validity of the model developed.

[1] R. Sun, H. Xiao, Diffusion-based coarse graining in hybrid continuum-discrete solvers: Theoretical formulation and a priori tests, Int. J. Multiph. Flow. 77 (2015) 142–157. doi:10.1016/j.ijmultiphaseflow.2015.08.014.

[2] R. Sun, H. Xiao, Diffusion-based coarse graining in hybrid continuum – discrete solvers : Applications in CFD – DEM, Int. J. Multiph. Flow. 72 (2015) 233–247.