Numerical analysis on the fluidization dynamics of rodlike particles

- DEM-CFD simulation of the gas fluidization of rodlike particles is reported.
- Bed permeability depends on both the porosity and particle shape.
- Rodlike particles have smaller contact forces and larger fluctuation velocities.
- The variation of particle orientation can be greatly related to bubble dynamics.

Fluidization of non-spherical particles widely exists in various engineering applications, such as biomass utilization and catalytic reaction. In this work, a mathematical analysis of particle fluidization has been carried out by employing a combined approach of discrete element method (DEM) and computational fluid dynamics (CFD). The emphasis is focused on the influence of the aspect ratio on the fluidization behavior of rodlike particles. The predictions of the minimum fluidization velocity are comparable to the available empirical correlations. The bed permeability and coordination number are determined by both the bed porosity and the particle shape. Meanwhile, the particle shape has a significant effect on the contact force and particle velocity. The results suggest that the shape parameters such as the sphericity or aspect ratio should be taken into account when establishing a phase diagram in terms of the coordination number and porosity. The evolution of particle orientation is strongly related to the dynamics of bubbles, and the degree of horizontal alignment of particles could be greatly reduced as the bed is well fluidized. These findings would be of interest from applied standpoints as well as showing fundamental effects of the particle shape on the fluidization dynamics.

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