عنوان مقاله [English]
In practice, U-shaped channels are used in urban sewer networks. Also, most of aqueducts in Iran are made of U-shaped channels. In this study the flow field turbulence and free surface variations within the
U-shaped channels along a side weir are simulated using the FLOW-3D and RNG turbulence models and the volume of fluid (VOF) scheme, respectively. Comparison between the experimental and numerical results shows that the numerical model predicts the flow field characteristic with reasonable accuracy. Then, the effects of the side weir length change on the free surface and the flow pattern in U-shaped channels are investigated. According to the simulation results, the free surface variations are not significant at the side weir upstream and, so the side weir effects could be ignored. For the L/D=3 case, before the side weir, the free surface flow is affected by the weir and a height difference is observed in all longitudinal profiles. Also, a surface jump occurs for both L/D=2 and L/D=3 cases in the downstream end of the side weir. According to the simulation results, a secondary flow is created after the side weir so that the cell of this secondary flow develops by proceeding to the main channel downstream. The specific energy variation in the upstream and the downstream of the side weir for L/D=2 case is computed to be about 1.18% in average.
Aydin, M. C. 2012. CFD simulation of free-surface flow over triangular labyrinth side weir. Adv. Eng. Software. 45(1): 159-166.
Aydin, M. C. and Emiroglu, M. E. 2013. Determination of capacity of labyrinth side weir by CFD. Flow Meas. Instrum. 29(1): 1-8.
Azimi, H., Shabanlou, S. and Salimi, M. S. 2014. Free surface and velocity field in a circular channel along the side weir in supercritical flow conditions. Flow Meas. Instrum. 38(1): 108-115.
Bagheri, S. and Heidarpour, M. 2012. Characteristics of flow over rectangular sharp-crested side weirs. J. Irrig. Drain. Eng. 138(6): 541-547.
Borghei, S. M., Jalili, M. R. and Ghodsian, M. 1999. Discharge coefficient for sharp crested side-weirs in subcritical flow. J. Hydraul. Div. 125(10): 1051-1056.
De Marchi, G. 1934. Saggio di teoria del funzionamento degli stramazzi laterali. Energia Elettrica. 11(11): 849-860. (in Italian)
El-Khashab, A. and Smith, K. V. H. 1976. Experimental investigation of flow over side weirs. J. Hydraul. Div. 102(9): 1255-1268.
Emiroglu, M. E., Agaccioglu, H. and Kaya, N. 2011. Discharging capacity of rectangular side weirs in straight open channels. Flow Meas. Instrum. 22(4): 319-330.
Hager, W. H., Hager, K. and Weyermann, H. 1983. Die hydraulische Berechnung von Streichwehren in Entlastungsbauwerken der kanalis ationstechnik. Gas-Wasser-Abwasser, 63, 309-329. (in German)
Novak, G., Kozelj, D., Steinman, F. and Bajcar, T. 2013. Study of flow at side weir in narrow flume using visualization techniques. Flow Meas. Instrum. 29(1): 45-51.
Qu, J. 2005. Three dimensional turbulence modeling for free surface flows. Ph. D. Thesis, Concordia University, Montreal, Quebec, Canada.
Tadayon, R. 2009. Modeling curvilinear flows in hydraulic structures. Ph. D. Thesis, Concordia University, Montreal, Quebec, Canada.
Uyumaz, A. 1997. Side weir in U-shaped channels. J. Hydraul. Eng. 123(7): 639-646.
Uyumaz, A. and Muslu, Y. 1985. Flow over side weirs in circular channels. J. Hydraul. Eng. 111(1):
Vatankhah, A. R. 2013. Water surface profiles along a rectangular side weir in a U-shaped channel. J. Hydrol. Eng. 18(5): 595–602.
Vatankhah, A. R. and Bijankhan, M. 2009. Discussion of ‘method of solution of non-uniform flow with the presence of rectangular side weir. J. Irrig. Drain. Eng. 135(6): 812-814.
Venutelli, M. 2008. Method of solution of nonuniform flow with the presence of rectangular side weir. J. Irrig. Drain. Eng.134(6): 840-846.
Yüksel, E. 2004. Effect of specific energy variation on lateral overflows. Flow Meas. Instrum. 15(5-6): 259-269.