[SCG64-P12] Experimental Investigation of Vertical Concentration Profile and Entrainment Rates of Mixed Grain-size Particles in Turbidity Currents
Keywords:flume experiment, mixed grain-size particles, vertical concentrantion profile, entrainment rate
Firstly, we report vertical profile of concentration of mixed grain-size sediments in experimental turbidity currents. For the experiments using uniform and nonuniform sediment, the vertical profiles suggested that the distribution of concentration of finer particles is less stratified than the coarser particles, and finer particles have more capability to diffuse upward, which tends to approximately uniform distribution above a certain height. Comparing to the result of Sequeiros et al. (2010), the vertical profiles of dimensionless distribution of suspension concentration shows no significant difference between uniform and mixed-grain sediments, which represented the vertical profiles of concentration of particles have identical assessment between turbidity currents and dense saline underflows.
Secondly, we examined the entrainment rate of basal sediment to suspension in turbidity currents, and compared our measurements with the prediction using the empirical formulation proposed by Garcia and Parker (1991, 1993). In the uniform particle experiments, the prediction of entrainment of sediment is consistent with the measurement accurately, whereas in the mixed grain-size particle experiments, it represent less consistent to anticipation. This implies that the new empirical formulation is needed for predicting entrainment rate of the mixed grain-size sediments into suspended load.
Garcia, M., and Parker, G. (1991). ‘‘Entrainment of bed sediment into suspension.’’ J. Hydraul. Eng., 117(4), 414–435.
Garcia, M., and Parker, G. (1993). ‘‘Experiments on the entrainment of sediment into suspension by a dense bottom current.’’ J. Geophys. Res., 98(3), 4793–4807.
Sequeiros, O.E., et al. (2010). “Characteristics of velocity and excess density profiles of saline underflows and turbidity currents flowing over a mobile bed.” J. Hydraul. Eng., 136(7), 412-433.