Abstract
AbstractParticle‐resolved direct numerical simulations are performed to simulate the flow through particle assemblies that are either static or freely moving to demonstrate the influence of particle mobility. To obtain a comprehensive understanding for this influence essential parameters such as the Reynolds number, solids volume fraction, particle‐fluid density ratio, collision parameters and particle shape are varied. The influence of particle mobility is assessed by evaluating the particle‐fluid forces, the particle ensemble structure and particle velocities. It is found that the ability of existing correlations for static particle systems to predict drag and lift forces correctly in dynamic particle‐gas flows is limited and that drift forces perpendicular to the drag force play an important role.
Highlights
Fluidized systems occur in a wide range of industrial application such as drying, coating, granulation, gasification, or combustion
particle-resolved direct numerical simulations (PR-DNS) resolve the fluid flow around individual Lagrangian particles and allow a direct calculation of the particle-fluid forces acting upon the particles whose motion can be predicted by the discrete element method (DEM)
Regarding the moving case III, the DNS results of the present study further suggest that elasticity and friction significantly increase the drag force at intermediate and higher Reynolds numbers, which is a contrary observation to the Stokes regime where interphase drag is slightly reduced by the introduction of this collision behavior
Summary
Fluidized systems occur in a wide range of industrial application such as drying, coating, granulation, gasification, or combustion. Numerical simulations of fluidization processes play an increasingly important role in the design and optimization thereof and can be divided into three different classes: microscopic particle-resolved direct numerical simulations (PR-DNS), mesoscopic EulerLagrange DEM-CFD simulations and macroscopic twofluid model (TFM) simulations [1]. PR-DNS resolve the fluid flow around individual Lagrangian particles and allow a direct calculation of the particle-fluid forces acting upon the particles whose motion can be predicted by the discrete element method (DEM). Unresolved DEM-CFD simulations consider the motion of individual particles, but rely on using a computational fluid dynamics (CFD) method to solve the volume-averaged Navier-Stokes equations in which the assumed fluid cell size is usually larger than the particle diameter. In TFM simulations both, the fluid and the solid phase, are solved using volume-averaged equations and the motion of single particles is not tracked
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