Author(s): Fereshteh Bagherimiyab
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Abstract: To predict sediment movement and its impact on processes in the water column in unsteady sediment-laden water flows is essential. The relationship between the dynamics of turbulent unsteady (accelerating) depth-varying openchannel flow over a movable (but not moving) coarse gravel bed (D50 = 5.5 mm) and fine sediment resuspension has been investigated. The thickness of the fine sediment (mean particle size about 160 Pm) layer on the gravel bed was varied. Experiments were carried out without and with fine sediment. The hydrograph was repeated up to 20 times and the unsteady flow was segmented into more than 100 time slices. Using acoustic Doppler and imaging methods, quasi-instantaneous profiles of velocity and sediment concentration were taken simultaneously. Flow visualization was made in parallel with a high-speed camera. Results with and without fine sediments were compared. The event structure of resuspension is made evident.
Year: 2009