Ecology, Environment and Conservation Paper

NUMERICAL STUDY OF FLOW PATTERN IN RECTANGULAR CHANNELS WITH SIDE INTAKE

Ali Saeidpur and Saeid Shabanlou1

Abstract

In this study, the flow field in 90-degree side intakes is simulated using the FLOW-3D software. The changesof the free surface are modeled by the VOF scheme. In this numerical simulation, for validating the numericalmodel results the experimental measurements conducted by Ramamurthy et al. (2007) were used. Theexperimental model is composed of a rectangular side intake attached to the main channel with a 90-degreeangle. The longitudinal slope of both main and side channels is equal to zero and the whole experimentalapparatus is installed horizontally for simulating the flow field turbulence, the standard k-ε and RNG k-εturbulence models are used. According to the numerical modeling results, the RNG k-ε turbulence modelestimated the flow field turbulence with a higher accuracy. The mean absolute percent error (MAPE) forthe standard k-ε and RNG k-ε turbulence models was calculated 2.020 and 1.996, respectively. The value ofMAPE for the longitudinal axis near the inner wall, the central axis and the outer wall of the side channelwas estimated 1.789, 1.996 and 2.315, respectively. Thus, the numerical model models the variations of theflow field free surface with acceptable accuracy. Subsequently, the effects of the channel bed slope on theflow pattern of side intakes with a 90-degree connection angle are investigated. According to the resultsobtained from the effects of the channel bed slope, the value of the flow field dynamic viscosity increases.By increasing the channel bed slope up to 0.025, the maximum Froude number of the flow is obtained equalto 1.998, which indicated the supercritical flow regime occurrence at the beginning of the downstreamchannel. According to the numerical simulation results, by increasing the channel bed slope the amount ofthe turbulence energy of the computational field increases as well.