Investigation of Characteristics of Separation Zones in T-Junctions HAMID SHAMLOO *, BAHAREH PIRZADEH ** Civil Engineering Department K.N Toosi University of Technology No.1346 Valiasr Street, Tehran IRAN *hshamloo@yahoo.com , ** b.pirzadeh@gmail.com Abstract: The river diversion, for domestic, agricultural and industrial consumption, has a vital role to make economic progress and to develop the human communities. There are different ways of river diversion which are proportional to rivers' condition and the quantity of the diversion of water. Lateral river intake is one of these ways. This paper provides detail application of FLUENT-2D software in simulation of lateral intake flows. Numerical simulations undertaken in present two dimensional work use RSM turbulent model. Results of velocity field measurement using K-ε Standard model were compared with Shettar & Murthy (1966). Then using RSM turbulent model, dimensions of separation zone were measured and compared with Kasthuri & Pundarikanthan (1987). In both cases good agreement are found between numerical and experimental results. Key-Words: Open channel, Lateral Intake, Turbulence, Separation zone, Numerical modeling, Fluent 1 Introduction In hydraulic and environmental engineering, one commonly comes across branching channel flows. Some of distinctive characteristics of a dividing flow in an open channel are illustrated in Fig.1. A zone of separation near the entrance of the branch channel, a contracted flow region in the branch channel, and a stagnation point near the downstream corner of the junction can be observed. In the region downstream of the junction, along the continuous far wall, separation due to flow expansion may occur (Ramamurthy et al. 2007). Fig.1. Flow characteristics of a dividing flow in open channels Flows through lateral intakes adjoining rivers and canals are turbulent. The transverse pressure gradients in the vicinity of the intake induce region of mean-velocity gradients, depth-varying surface of flow division and separation, vortices, and zone of flow reversal. As the flow approaches the intake, it accelerates laterally by the suction pressure at the end of branch channel. This may cause the flow to divide into two portions, one entering the branched channel and the other flowing downstream in the main channel. The diverted flow experiences an imbalance between the transverse pressure gradient and shear and centrifugal forces indicating a clockwise secondary motion cell (Neary et al. 1999). A great number of experimental and analytical studies are dealt with dividing flows. Taylor (1944) conducted the first detailed experimental study in an open channel and proposed a graphical solution, which included a trial-and-error procedure. Grace and Priest (1958) presented experimental results for division of the flow with different width ratios of the branch channel to the main channel. They also classified division of the flow into two regimes, with and without the appearance of local standing waves near the branch. The regime without waves corresponded to the case where the Froude numbers were relatively small, and the regime with waves corresponded to the free over-fall conditions at WSEAS TRANSACTIONS on MATHEMATICS Hamid Shamloo and Bahareh Pirzadeh ISSN: 1109-2769 303 Issue 5, Volume 7, May 2008