Particle behavior in a turbulent pipe flow with a flat bed

Particle behavior in a turbulent flow in a circular pipe with a bed height h=0.5R is studied at Reb=40,000 and for two sizes of particles(5μm and 50μm)using large eddy simulation,one-way coupled with a Lagrangian particle tracking technique.Turbulent secondary flows are found within the pipe,with the curved upper wall affecting the secondary flow formation giving rise to a pair of large upper vortices above two smaller vortices close to the pipe floor.The behavior of the two sizes of particle is found to be quite different.The 50μm particles deposit forming irregular elongated particle streaks close to the pipe floor,particularly at the center of the flow and the pipe corners due to the impact of the secondary flows.The deposition and resuspension rate of the 5μm particles is high near the center of the floor and at the pipe corners,while values for the 50μm particles are greatest near the corners.Near the curved upper wall of the pipe,the deposition rate of the 5μm particles increases in moving from the wall center to the corners,and is greater than that for the larger particles due to the effects of the secondary flow.The maximum resuspension rate of the smaller particles occurs above the pipe corners,with the 50μm particles showing their highest resuspension rate above and at the corners of the pipe.