Flow characteristics and packing structures of dense granular flow around an immersed cylindrical tube

We perform discrete element simulations to investigate the influence of the flow velocity, the particle size, and the particle-particle sliding friction on flow patterns and packing structures of dense granular flow around an immersed cylindrical tube. Results indicate that varying the flow velocity and particle radius does not obviously affect the scaled velocity field. However, increasing the velocity enhances the vertical motion of particles near the void space and increasing the particle size reduces the particle flowability in the horizontal direction. Both effects result in the enlargement of the void space below the tube. Moreover, larger particle friction leads to a looser packing structure and a larger void region. The width and the depth of the void region increase with the friction in an exponential form. The simulation results in this work help to understand the origin of the complex flow structures in moving bed particle heat exchangers. (C) 2022 Elsevier Ltd. All rights reserved.