Numerical study of flow pattern in rectangular channels with side intake

摘要

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