Particle resolved direct numerical simulation of a liquid-solid fluidized bed: Comparison with experimental data

A. Ozel (1) , J.C. Brändle de Motta (2) , Micheline Abbas (3) , Pascal Fede (4) , Olivier C Masbernat (3) , Stéphane Vincent (5) , J.-L C Estivalezes (6) , O C Simonin (7)

1 Princeton University
2 IMFT - Institut de mécanique des fluides de Toulouse
3 LGC - Laboratoire de Génie Chimique
4 UT3 - Université Toulouse III - Paul Sabatier
5 MSME - Laboratoire de Modélisation et Simulation Multi Echelle
6 ONERA - The French Aerospace Lab [Toulouse]
7 Toulouse INP - Institut National Polytechnique (Toulouse)

Particle-resolved direct numerical simulations of a 3-D liquid-solid fluidized bed experimentally investigated by Aguilar-Corona (2008) have been performed at different fluidization velocities (corresponding to a range of bed solid volume fraction between 0.1 and 0.4). Particle Reynolds number and Stokes number are O(100) and O(10), respectively. In these simulations, the flow is solved by a one-fluid formulation of the incompressible Navier-Stokes equations, where the pressure-velocity coupling is provided by an algebraic augmented Lagrangian method. The particle presence is modeled by an implicit penalty fictitious domain method and the particle-to-wall and particle-to-particle interactions are taken into account by a linear spring-dashpot model and a sub-grid scale lubrication force.In this paper, we compare the statistical quantities computed from numerical results with the experimental data obtained with 3-D trajec-tography and High Frequency PIV. Fluidization law predicted by the numerical simulations is in very good agrement with the experimental curve and the main features of trajectories and Lagrangian velocity signal of the particles are well reproduced by the simulations. The evolution of particle and flow velocity variances as a function of bed solid volume fraction is also well captured by the simulations. In particular, the numerical simulations predict the right level of anisotropy of the dispersed phase fluctuations and its independence of bed solid volume fraction. They also confirm the high value of the ratio between the fluid and the particle phase fluctuating kinetic energy. A quick analysis suggests that the fluid velocity fluctuations are mainly driven by fluid-particle wake interactions (pseudo-turbulence) whereas the particle velocity fluctuations derive essentially from the large scale flow motion (recirculation). Lagrangian autocor-relation function of particle fluctuating velocity exhibits large-scale oscillations, which are not observed in the corresponding experimental curves, a difference probably due to a statistical averaging effect. Evolution as a function of the bed solid volume fraction and the collision frequency based upon transverse component of particle kinetic energy correctly matches the experimental trend and is well fitted by a theoretical expression derived from Kinetic Theory of Granular Flows.

Mots clés: particle and fluid agitation; liquid-solid fluidized bed; Particle-resolved DNS

Domaines: Mécanique des fluides [physics.class-ph]

A. Ozel, J.C. Brändle de Motta, Micheline Abbas, Pascal Fede, Olivier C Masbernat, et al.. Particle resolved direct numerical simulation of a liquid-solid fluidized bed: Comparison with experimental data. International Journal of Multiphase Flow, 2017, 89, pp.228-240. ⟨10.1016/j.ijmultiphaseflow.2016.10.013⟩. ⟨hal-01420241⟩