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Conf’luence Dr. Berend Van Wachem

31 janvier 2011

Modeling of gas-solid turbulent flows with non-spherical particles
10 février 2011 à 10h
Amphithéâtre Nougaro
Dr. Berend Van Wachem, Department of Mechanical Engineering, Imperial College London

Résumé :
In this presentation, I will discuss a computational model to simulate the behaviour of turbulent flows laden with non-spherical particles. The computational model comprises different elements.

  • Firstly, the drag, torque and lift relations of each particle shape is determined by means of true DNS, where the particle is represented by the mirroring immersed boundary method. A large number of simulations is performed for each particle, to gather data on the drag, torque, and lift on the particle under various Re numbers and angles of attack. All these simulations are coarse-grained into drag, lift and torque correlations.
  • Secondly, the resulting relations are used in a fully coupled point-particle approach of a horizontal channel flow using the Large Eddy Simulation (LES) framework. The horizontal channel flow properties are based on the experimental and modeling work. The Re number of the flow through the channel is around Re _ 22, 500, the particle equivalent diameter is dp = 200 μm and the mass loading of the particles is m = 1.0. Three types of particles were studied : two types of ellipsoids and disk-shaped particles.
  • Thirdly, because of the high mass loading, a novel collision model to deal with the collisions between nonspherical particles and the particles and the wall is constructed based upon a Quaternion approach.

    Simulations were performed of these 3 shapes of particles and compared to simulations with spherical particles and the available experimental data. Figure 1 shows some preliminary results. The results show there is a big effect of particle shape and particle-orientation. The effect of the walls on the particle orientation is shown in the figure below on the right. Also, the concentration profiles differ significantly, due to the variation in upward effect of the turbulence. Finally, the effect of wall roughness one the particle flow and orientation is discussed.