Sediment Entry Investigation at the 30 Degree Water Intake Installed at a Trapezoidal Channel
2 Abstract: A major problem which most of lateral intakes are faced with is sedimentation and sediment delivery. This process causes many problems such as reduction flow discharge capacity in irrigation canals as well as threatening of blockage of water during low water flow. Therefore it is the main goal of engineer to design an intake with higher flow discharge and low sediment delivery. Since most of lateral intakes are installed at trapezoidal which has not received the same attention as intake from rectangular canals, it is the main goal of this study to investigate sediment delivery to an intake from trapezoidal canal. In this study, sediment tests carried out for different hydraulic conditions at a 30 degree water intake installed at main channel with inclined bank. From analysis of these it was found that the flow patterns at the upstream of the intake has been modified in such a way that more water from surface layers are diverted. Therefore less suspended sediment enters the intake. Also it was found that in all tests the amount of sediment enters the intake reaches its minimum value at Froude Number between o.35 to o.4. In low flow depth because of the effect of bed roughness over strength of secondary current, the suspended sediment enters the intake is lower compare to the higher flow depth for the same conditions.
THREE-DIMENSIONAL NUMERICAL MODEL OF LATERAL-INTAKE INFLOWS
A three-dimensional (3D) numerical model for predicting steady, in the mean, turbulent flows through lateral intakes with rough walls is developed, validated, and employed in a parametric study. The method solves the Reynolds-averaged Navier-Stokes equations closed with the isotropic k-ω turbulence model of Wilcox, which resolves the near-wall flow and accounts for roughness effects in a straightforward manner. Calculations are carried out for flows through rectangular closed-duct and open-channel T-junctions. Comparisons of the predicted mean velocity field with laboratory measurements indicate that the model captures most experimental trends with reasonable accuracy. For the parametric study, flows are predicted for a range of discharge ratios, aspect ratios, and main channel-bed-roughness distributions. The numerical solutions are examined to elucidate the complex 3D flow patterns of lateral-intake flows, including zones of flow division, separation and reversal, vortices, and singular points within th...
Steady flow in a model of the human carotid bifurcation. Part I--flow visualization.
The geometry of a typical adult human carotid bifurcation, complete with the sinus, was established from a study of a large number of angiograms. A rigid model was constructed from glass and investigations were performed under steady flow conditions using flow visualization techniques over a range of upstream Reynolds numbers and flow division ratios through the branches representative of physiologic conditions expected in the human vasculature. The study reveals a complex flow field in which secondary flows play an important role. The separation regions occurring at the outer corners of the branching are also subjected to much higher shear stress. Comparison with pathologic data on localization of atherosclerotic lesions indicates that zones susceptible to disease experience low or oscillatory shear stress while regions subject to higher shear are free of deposits.