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Numerical Investigation of Sluice Gates' Shape Factor on Contraction Coefficient Original Article, B13 Sadeghfam S and Akhtari AA. Journal. Civil Eng. Urban. 2(2): 72-74. 2012. ABSTRACT:The behavior of flow under sluice gate and determining the water profile is one of the important issues in hydraulic engineering. In this study the contraction coefficient is studied and the effect of slice gate's shape is observed numerically by CFD model. The turbulence model k-e (RNG) and unsteady flow mode are used in analysis of two dimensional gates. Three types of slice gate's shapes are analyzed and contraction coefficient of these cases is presented and compared with experimental and theoretical results of other researchers. It is worth mentioning that for these cases the equations in terms of the ratio of gate opening to depth of approaching flow behind gate, are collected. So the gate's shape has significant role on contraction coefficient and between 3 types of gate's shapes that are investigated in this research, contraction coefficient of the sluice gate with shape of two side slope (case 3) has larger amount of this coefficient. Keywords: Sluice Gate, CFD model, Contraction Coefficient, Turbulence Model k-e (RNG) منبع: [Hidden Content] دانلود: [Hidden Content].,B13-72-74.pdf J. Civil Eng. Urban.,B13-72-74.pdf

Numerical Investigation of Length and Thickness of Separation Zone after Sudden Change of Direction in Closed Sections Original Article, B6 Sadeghfam.S, Akhtari.A.A. Journal. Civil Eng. Urban. 2(1): 35-39. 2012. ABSTRACT: Separation phenomenan which is created in result of the inverse pressure gradient reduces the efficiency of the hydraulic systems. Due to eddy flows, analytical solution is not possible. In this paper, the relationship between the length and the thickness of the separation zone versus velocity variations has been investigated by using Fluent, in closed sudden change of direction in square sections with different divergence angles. First, to verify the accuracy of the numerical model, and some other factors such as turbulent model, the results of numerical model have been compared with experimental results in a sudden expansion at several sections. Based on the results of sudden expansion analysis, the turbulence model k-e (RNG) and steady flow mode are used in analysis of two dimensional bends. The results show that for the sharp curvature with central angle of 45 degrees regardless of flow velocity, separation in internal wall doesn't happen. For the sudden change of direction with a central angle of 45 to 90 degrees, flow separation is the function of divergence angles and flow velocity. In this study, the equations in terms of length and thickness of the separation are collected via abundant numerical analysis. Keywords: Separation, Inverse Pressure Gradient, Sudden Change of Direction, Fluent, Turbulent Model k-e (RNG) منبع: [Hidden Content] دانلود: [Hidden Content].,B6-35-39.pdf J. Civil Eng. Urban.,B6-35-39.pdf