الفهرس 
Open Channel Junctions Applications
Corners Shape at the junctionOnly 14 pages are availabe for public view
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Abstract
Junctions in open channel flow refer to any side water secession from natural or artificial channels.Branching channels located in various applications, such as irrigation and drainage network systems, water,and wastewater treatment plants. In the last decades, comprehensive investigations on the dividing flow in open channel junctions have been executed to understand the characteristics of the separating flow, varying from numerical studies to theoretical and experimental investigations. This study tries to fill the gap of junction’s field experiments and its numerical simulations as well.
For this purpose, three Egyptian branching canals withangles about30º,45º, and90ºat El-Mahalla El-Kubra, Egypt, were chosen and surveyed. Calculations and measurements of 45 different discharges, ranging from 0.456 to 14.919 m3/sec, were measured to achieve the accurate stage discharge relationship in nine sections at five water levels. A 3D turbulence model with ANSYS Fluent software was used to reproduce the flow characteristics of the field junctions with irregular shapes. Also, the numerical model was used to reproducethe flow characteristics of30º, 45º,60º,75º, and90ºangles open channel junction withrectangular cross-section shaped with a horizontal bed and various width ratios.The modeling is based on the Navier-Stokes equation and κ-ω turbulent model.Anearlier general analytical solution to solve the subcritical dividing steady flow in natural and rectangular open channel junction was validated using field and numerical data. For validation, a comparisonwas conducted among the numerical solution, and the analytical model with previous study. The results showed that the numerical solution gave a good agreement. The analytical solution gave a large error than numericalfor the rectangular sections. Comparing results obtained from the numerical model with field investigation data performed on a typical Egyptian canal appeared good agreement with a maximum discrepancy of 1.691%. Whereas the analytical solution gave a big error than a numerical one with a maximum discrepancy of 13.526% for irregular sections than the field data.Themaximum discrepancywas 13.409 for the rectangular section with various geometrizesand angleswith reference to the numerical results. Relations between the discharge ratio with the upstream Froude number and depth ratio for the rectangular and irregular sections were proposed. The maximum discrepancy in the irregular section used the proposed equations equals to 0.779% with reference to the field data recorded and equals to 17.438% in the rectangular sections with reference to the numerical results. Also,general equations were proposed to calculatethe dimensionless separation zone shear force valuefor rectangular open channel junction related to upstream Froude number,and thebranch angledepth ratio. Results showed that the analytical model is more suitable to apply with rectangular cross section and natural channels with semi-rectangular cross section.Also, the modelwasefficient to estimate the dimensionless separation zones shear forceaccurately. Surface topography profiles were declared in the numerical results. Also, five different patterns of separation zone on the horizontal plan were observed and indicated numerically inthe rectangularchannel section.However,the simulation indicated various patterns of separation zones formed in irregular field junctions.