Flow regimes and characteristics of dense particulate flows with coarse particles in inclined pipe

Abstract

This paper presents a numerical simulation for dense particulate flows with coarse particles in inclined pipe to identify different flow regimes by means of computational fluid dynamics-discrete element method. The drag, gravitational, pressure gradient and virtual mass forces on particles, as well as the effect of particle–particle collisions are considered. Two flow regimes and their transitions are observed and described. The influence of Stokes number St, Froude number Fr, inclination angle β, etc., on critical flow regimes is analyzed to identify the dependence of flow regimes on these parameters. A new diagram for recognizing regime transition is given. The temporal variations of flow fields are also analyzed to illustrate propagating of kinematic waves. The wave velocity increases with Fr, β, and particle concentration increasing. Two dimensionless numbers, collision stress and fluid–particle interaction stress, are defined to explain the regime transition mechanism. The maximum pressure drop occurs at approximately β = 60°.