Vol14 No.9: 1728-1738
【Title】The properties of dilute debris flow and hyper-concentrated flow in different flow regimes in open channels
【Author】LIU Yan1; WANG Hui-feng1; CHEN Hua-yong2; HU Kai-heng2; WANG Xie-kang1*
【Addresses】1 State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610065, China; 2 Institute of Mountain Hazards and Environment, CAS, Chengdu 610041, China
【Citation】Liu Y, Wang HF, Chen HY, et al. (2017) The properties of dilute debris flow and hyper-concentrated flow in different flow regimes in open channels. Journal of Mountain Science 14(9). https://doi.org/10.1007/s11629-016-4132-y
【Abstract】Particle Image Velocimetry (PIV) technique was used to test the analogues of hyper-concentrated flow and dilute debris flow in an open flume. Flow fields, velocity profiles and turbulent parameters were obtained under different conditions. Results show that the flow regime depends on coarse grain concentration. Slurry with high fine grain concentration but lacking of coarse grainsbehaves as a laminar flow. Dilute debris flows containing coarse grains are generally turbulent flows. Streamlines are parallel and velocity values are large in laminar flows. However, in turbulent flows the velocity diminishes in line with the intense mixing of liquid and eddies occurring. The velocity profiles of laminar flow accord with the parabolic distribution law. When the flow is in a transitional regime, velocity profiles deviate slightly from the parabolic law. Turbulent flow has an approximately uniform distribution of velocity and turbulent kinetic energy. The ratio of turbulent kinetic energy to the kinetic energy of time-averaged flow is the internal cause determining the flow regime: laminar flow ( < 0.1); transitional flow (0.1 < < 1); and turbulent flow ( > 1). Turbulent kinetic energy firstly increases with increasing coarse grain concentration and then decreases owing to the suppression of turbulence by the high concentration of coarse grains. This variation is also influenced by coarse grain size and channel slope. The results contribute to the modeling of debris flow and hyper-concentrated flow.
【Keywords】Hyper-concentrated flow; Debris flow; Flow regime; Velocity profile; Turbulent kinetic energy;Open channel