Frequency pattern of turbulent flow and sediment entrainment over ripples using image processing

摘要: River channel change and bed scourings are source of major environmental problem for fish aquatic habitat. The form such as ripples dunes is the result an interaction between turbulent flow structure sediment particles at bed. over important to understand initiation entrainment its transport. focus this study measurement analysis dominant bursting events in a channel. Two types with sinusoidal triangular forms were tested study. velocities measured three dimensions using Acoustic Doppler Velocimeter sampling rate 50 Hz. These different points within depth from longitudinal positions along flume. A CCD camera was used capture 1500 sequential images monitor movement Application image processing technique enabled us compute number entrained deposited ripples. From quadrant decomposition instantaneous velocity fluctuations close bed, it found that downstream second ripple, Quadrants 1 3, whereas upstream 2 4 dominant. More importantly consideration these results indicates normalized occurrence probabilities sweep phase those ejection out form. Therefore would be expected occur deposition occurs ripple. expectations confirmed by above information can practical application rivers where restoration required.