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REMOVAL OF TANK AND SEWER SEDIMENT BY GATE FLUSHING: COMPUTATIONAL FLUID DYNAMICS MODEL STUDIES
Citation:
Fan*, C, R. Raghavan, AND J. Chan. REMOVAL OF TANK AND SEWER SEDIMENT BY GATE FLUSHING: COMPUTATIONAL FLUID DYNAMICS MODEL STUDIES. Presented at 2002 Flow-3D Users Conference, Santa Fe, NM, 9/30-10/2/2002.
Description:
This presentation will discuss the application of a computational fluid dynamics 3D flow model to simulate gate flushing for removing tank/sewer sediments. The physical model of the flushing device was a tank fabricated and installed at the head-end of a hydraulic flume. The flushing system was also mathematically simulated using a 3D flow computational model based on the fundamental laws of mass, momentum and energy conservation. Finite-difference approximations are used to enforce conservation equations. The flow model uses a fixed-grid (Eulerian) of rectangular elements; the fluid moves through the grid (Eulerian approach) and free surfaces are tracked with the Volume-of-Fluid (VOF) technique. Sediment is treated as a continuous phase, with the two components of scour and drifting and lifting, superimposed on the advection of the sediment with the fluid. The effects of particle interaction and the angle of repose of the sediment are included in the model. Regions where the sediment reaches the packing concentration are frozen, mimicking a solid material. In the hydraulic flushing tests the flushed sediments were collected at the end of the flume and weighed. The test and model results suggest that the weight of flushed sediments increases with the initial water volume in the flushing device and decreases with the increading initial water depth in the flume.