Based on the CFD-DEM coupling method and the sand-water coaxial jet experiment,a model for the underwater movement of sediment clouds has been established.The underwater movement characteristics of sediment clouds with three different particle sizes of 0.25 mm,0.50 mm,and 0.75 mm are analyzed,the re-sponses of the center velocity of water and sediment to four different shapes of discharge orifices with circular,coaxial annular,square and triangular sections are studied.The results indicate that the sediment cloud formed after discharging sediment into the water can be considered as a spherical front dominated by sediment phase and a cloud tail dominated by the liquid phase.The geometric shape of the cloud after touching the bottom can be regarded as a steady-state sediment jet.The shape of the water flow section is consistent with the shape of the orifice section in the initial stage of cloud movement,and gradually transforms into a circle with the settling process.The movement pattern during the settling and spreading processes of the cloud is directly related to the particle size of the sediment.The influence of the shape of the orifice section on the center velocity of the cloud extends to approximately 7 times the inner diameter of an equally sized circular outlet.The center veloci-ty of sediment cloud clusters dropped from non-circular discharge orifices within the influence range is fast,but the velocity attenuation rate is high.
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