2024 Volume 80 Issue 16 Article ID: 23-16089
We performed flume experiments of sediment flows containing two-particle-size and investigated the effect of the dimensionless flow depth which is defined the ratio of flow depth to large particle size on concentration of large particles at the sediment flow's front which are characteristic phenomena in mixedsize sediment flows. The experiments were performed under different conditions of the flow rate, channel gradient, and particle size that are related to changes in dimensionless flow depth. It was found that large particles did not concentrate at the flow's front in the range of the dimensionless flow depth roughly less than 1 in the experiment's results. Result of particle's velocity by PIV analysis implied that in the range of the dimensionless flow depth less than or equal to 1, movement in the flow direction of large particles was suppressed due to decrease in buoyancy caused by protrusion of the particles to the water surface. In the range of the dimensionless flow depth roughly greater than 1, tendencies for the concentration of large particles at the flow's front were more pronounced in conditions in which the supply flow rate was higher, the channel gradient was lower, and particle size ratio was bigger when the channel gradient reduced.
