Experimental investigation of the motion states of coarse particles with sediment-laden flow in a horizontal pipe

This paper investigates coarse particle motion states via physical experiments of coarse particles and sediment -laden water or pure water flowing in a horizontal pipeline. The effects of coarse particle sizes, pipe flow velocities and coarse particle mass rates entering the pipeline are analyzed. The coarse particle motion can be divided into three regimes: plug, layer shift and mobile conveying. Regarding plug conveying, a particle plug is formed and moves as a head-to-tail transformation. Regarding mobile conveying, particles are in discrete contact with each other and move rapidly. The layer shift conveying is a transition stage, a continuous flat particle layer is formed at pipe bottom. The relationships among conveying regimes, instantaneous pressure, time-averaged pressure and fluctuating pressure features are clarified. A parameter is proposed to classify coarse particle motion states. Its accuracy is demonstrated using particle image velocimetry (PIV) and the relationships between conveying re-gimes and instantaneous pressure features.