Pore-scale simulation of flow and turbulence characteristics in three-dimensional randomly packed beds

Fluid flow and turbulence characteristics were numerically simulated at the pore scale in actual packed beds under different operating conditions. Real geometrical structures of randomly packed beds were modeled using the discrete element software LIGGGHTS (LAMMPS Improved for General Granular and Granular Heat Transfer Simulations). The numerical model was validated against experimental data. Good agreements were achieved between the predicted results and measurements. The influences of different parameters, such as the gas velocity and particle, size were studied and discussed in detail. The results of a macroscopic analysis of the mean parameters show that inside the packed beds, both the mean porosity and flow parameters had fluctuate variations. As the pellet radius increased, the fluctuations in the mean velocity and pressure increased. The results of a local detail analysis demonstrate that complicated turbulent eddy structures exist in the pores of the packed beds. Eddies with large sizes were primarily distributed at the entrance of the main channel and near the spherical wall, and eddies with high intensities were mainly distributed near the above spherical wall and on the right side of the main channel.