(624f) Microscopic Numerical Investigation of Dense Gas-Solid Flows Near a Solid Wall (Effects of wall on the behavior of particles)

Flow including dense solid particles often appears in industrial equipments such as fluidized beds and spouted beds used for combustion, catalytic reaction, granulation and coating processes.  To enable advanced designing and optimization of operating conditions, it is important to understand the flow behavior in the equipment in detail.  However, its behavior is complicated especially in the near-wall region.  A solid wall affects the flow directly by wall friction effect and the particle arrangement through the contacts between wall-particle and particle-particle.  Due to the difficulty of experimental observations, the effect of wall is not known well at present.  In the present study, the influence of solid wall on a flow field including dense moving particle is investigated in detail by means of microscopic direct numerical simulation.  Immersed boundary method is combined with discrete element method.  In order to investigate the influence of solid wall, sedimentation of dense particles near a vertical wall is simulated.  To perform the computations with reduced computational cost, a new mirror boundary condition is proposed, too.  It is confirmed that in near-wall region, the existence of the solid wall has significant effects both on particle and fluid flow structures. Moreover, sedimentation velocity of particles near solid wall is decreased and fluid resistance is increased due to the wall.