Turbulent Flow Structure and Flow Resistance of Hyper-concentratedSediment Laden Flow with Artificial Roughness

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Effects of regularly arrayed square roughness on flow resistanceand turbulent characteristics in an open channel have been investigated over a completelyrough-bed with uniform stainless square ribs. Detailed spatial measurements of streamwiseand vertical velocity fluctuations were conducted using Particle Image Velocimetry (PIV)in a vertical plane along the completely rough bed surface. Experimental results indicatedthat flow resistance with three-dimensional square roughness is higher than that withtwo-dimensional square roughness, the maximum value of flow resistance appeared intransverse spacingδ/ｋ （transverse spacing/roughness height ratio）=1 and significantdegrees of spatially regular variation in the time-averaged velocities were generatedalong the rough elements.Mud flows, debris flows or slurries, made up of a large amountof clay and/or silt particles suspended in water, often show non-Newtonian propertiesbut remain poorly understood concerning the impacts of their rheological properties onfully developed turbulent structure. In this study, we experimentally investigatedresistance and momentum transport of hyper- concentrated sediment laden-flow in an openchannel with two-dimensional square ribs by using Particle Image Velocimetry(PIV). Theresults showed that rheological properties significantly dissipated the turbulent flowfluctuations over the dune bed and augmented the flow resistance by comparison with theclear water flow