Experimental Investigation of Flow Field Due to Dual Offset Jets

Document Type : Research Article


1 Assistant Professor, Kharazmi University, Tehran, Iran

2 Professor, Hydraulic Engineering, Water Research Institute, Tarbiat Modares University, Tehran, Iran

3 Ex-Graduated Student, Tarbiat Modares University, Tehran, Iran


In this research the flow field and the correlation between the flow field and scour due to double jets in the preliminary stages are investigated. Two experiments were conducted with different densimetric Froude number in fixed bed and high tailwater depth condition. Comparisons between scour process and flow field are presented. According to the results of this research, appropriate parameters are presented to find the non-dimension at profiles, non-dimensional velocity decay, and velocity development in flow depth and non-dimensional form of velocity fluctuation such as velocity fluctuation component in vertical and streamwise directions and Reynolds stresses. Good agreement was found between present data and previous researchers data. The Reynolds stress investigations show that, the shear stress variation using different methods are approximately the same and the estimation of the shear stress with vertical velocity fluctuation gives larger values. In addition, difference between the bed shear stress estimation using different methods are large in the regions with higher values. The estimation of shear stress with Reynolds stresses has better correlation with scour process. The angles of ejection and sweep events do not have good correlation with scour process. 


مهرآیین م.، نوربخش م. و قدسیان م. (1394).  بررسی میدان جریان آشفته اطراف آبشکن T شکل مستغرق نشریه هیدرولیک- دوره 15 ، شماره 3، ص‌ص. 171-178.
مهرآیین م.، قدسیان م. و خسروی مشیزی م. (1395). بررسی تأثیر استغراق آبشکن بر پارامترهای آشفتگی در اطراف آبشکن مستقر در قوس90ᵒ، نشریۀ عمران مدرس، دورۀ 16، شمارۀ 2، ص‌ص. 243-257.
Agelin- Chaab, M. and Tachie, M.F. (2011). "Characteristics and structure of turbulent 3D offset jets." Int. J. Heat Fluid. Fl. 32(3), pp.608-620.
Bey, A. Faruque, M.D. and Balachandar, R. (2007). "Two-Dimensional scour hole problem: role of fluid structures", J. Hydraul. Eng. 133(4), pp.414- 431.
Bhuiyan, F., Habibzadeh, A., Rajaratnam, N. and Zhu, D.Z., (2011). "Reattached turbulent submerged offset jets on  rough beds with shallow tailwater." J. Hydraul. Eng. 137(12), pp.1636-1648.
Biron, P.M., Robson, C., Lapointe, M.F., and Gaskin, S.J. (2004). "Comparing different methods of bed shear stress estimates in simple and complex flow fields." Earth. Sutf. Proc. Land. 29(11), pp.1403–1415.
Bourque, C., and Newman, B. G. (1960). "Reattachment of a two- dimensional incompressible jet to an adjacent flat plate." Aeronautical Quarterly, 11(3), pp.201–232.
Breusers, H.N.C and Raudkivi, A.J. (1991). "Scouring: Hydraulic Structures Design Manual Series.", Volume 2 van IAHR Design Manual, Taylor & Francis.
Dey, D., and Eldho, T.I. (2009). "Effect of spacing of two offset jets on scouring phenomena." J. Hydraul. Res, 47(1), pp.82-89.
Dey, S, Nath, T. K and Bose, S. K. (2010). "Fully rough submerged plane wall-jets." J. Hydro-Environment Res. 4(4), pp.301-316.
Dey, S. and Sarkar, A. (2008). "Characteristics of turbulent flow in submerged jumps on rough beds." J.  Eng. Mech. 134 (1), pp.49-59.
Drake T.G., Shreve R.L., Dietrich W.E., Whiting P.J. and Leopold LB (1988). "Bed load transport of fine gravel observed by motion picture photography", J. Fluid. Mech. 192, pp.193–217
Duan, J.G. He, L. Wang, G.Q. and Fu, X.D. (2009). "Mean flow and turbulence around experimental spur dike." Adv. Water. Resour., 32(12), pp.1717–1725.
Goring, G. and Nikora, V.(2002). "Despiking acoustic doppler velocimeter data." J. Hydraul. Eng. 128( 1), pp.117-126.
Grass, A. J. (1971)."Structural features of turbulent flow over smooth and rough boundaries", Journal of Fluid Mechanics, 50(2), pp.233–255.
Holland, J. T., and Liburdy, J. A. (1990). "Measurements of the thermal characteristics of heated offset jet." Int. J. Heat. Mass. Tran. 33(1), pp.69–78.
Huthnance, J. M., Humphery, J. D., Knight, P. J., Chatwin, P. G., Thomsen, L., and White, M. (2002). "Near-bed turbulence measurements, stress estimates and sediment mobility at the continental shelf edge", Prog. Oceanogr.,52(2–4), pp.171–194.
Keshavarzy, A. R. and Ball, J. E. (1997). "An analysis of the characteristics of rough bed turbulent shear stresses in an open channel", Stoch. Env. Res. Risk. A. 11, pp.193–210.
Keshavarzy, A.R. and Gheisi, A.R. (2006). "Stochastic nature of three dimensional bursting events and sediment entrainment in vortex chamber", Stoch. Env. Res. Risk. A. 21(1), pp.75-87.
Kim, S.C., Friedrichs, C. T., Maa, J. P. Y., and Wright L. D. (2000). "Estimating bottom stress in tidal boundary layer from acoustic doppler velocimeter data." J. Hydraul. Eng. 126(6), pp.399–406.
Kishore, G. R., and Dey, S. (2016). "Hydraulics of submerged offset-jets." 6th International Symposium on Hydraulic Structures. Portland, Oregon, USA, DOI:10.15142/T3550628160853
Ko, N. W. M, and Lau, K. K (1989). "Flow structures in initial region of two interacting parallel plane jets", Exp. Therm. Fluid. Sci. 2(4), pp.431–449
Levin, S. G., and Manion, F. M. (1962). "Jet attachment distance as a function of adjacent wall offset and angle." Technical report, Harry Diamond Laboratories, Army Materiel Command, Washington DC.
Long, D., Steffler, P., and Rajaratnam, N. (1990). "LDA study of flow structure in submerged hydraulic jump." J. Hydraul. Res., 28(4), pp.437– 460.
Mianaei, S. and Keshavarzy, A.R. (2008) "Spatio-temporal variation of transition probability of bursting events over ripples at the bed of the open channel", Stoch. Env. Res. Risk. A. 22(2), pp.257-264.
Nakagawa, H. and Nezu, I. (1997). "Predictions of the contributions to the Reynolds stress from bursting events in open-channel flows", J. Fluid. Mech. 80(1), pp.99–128.
Nasr A. and Lai, J. C. S. (2000) "The effects of wall inclination angle on an inclined offset jet." Proceedings of 10th International Symposium on Applications of Laser Techniques to Fluid Mechanics, Lisbon, Portugal.
Nasr, A., and Lai, J. C. S. (1997) "Comparison of flow characteristics in the near field of two parallel plane jets and an offset plane jet", Phys. Fluids. 9(10), pp. 2919-2931.
Nelson J. M., Shreve R. L., Mclean S. R., and Drake T. G (1995). "Role of nearbed turbulence structure in bed load transport and bed form mechanics", Water. Resour. Res. 31(8), pp. 2071–2086.
Nezu, I. and Nakagawa, H. (1993). "Turbulence in open-channel flows." Balkema, Rotterdam, Netherlands.
Nychas S.G., Hershey H.C. and Brodkey R.S. (1973). "A visual study of turbulent shear flow." J. Fluid. Mech. 61, pp.513–540.
Pelfrey, J. R. R., and Liburdy, J. A. (1986). "Effect of curvature on the turbulence of a two-dimensional jet." Exp. Fluids. 4(3), pp.143–149.
Rajaratnam, N. (1965). "The hydraulic jump as a wall jet." J. Hydraul. Div. 91(5), 107-132.
Rajaratnam, N. (1976). "Turbulent jets." American Elsevier publication company, New York.
Rajaratnam, N. and Mazurek, K. (2003). "Erosion of sand by circular impinging water jets with small tailwater." J. Hydraul. Eng. 129(3), pp. 225-229.
Rajaratnam, N. and Subramanya, K. (1968). "Plane turbulent reattached wall jets." J. Hydraul. Div.
94(1), pp.95-112.
Sawyer, R. A. (1960). "The flow due to a two dimensional jet issuing parallel to a flat plate." J. Fluid. Mech. 9(4), pp.543–561.
Sawyer, R. A. (1963). "Two dimensional reattaching jet flows including the effect of curvature on entrainment." J. Fluid. Mech. 17(4), pp.481–498.
Soulsby, R. L. (1983). "The bottom boundary-layer in shelf seas." In Physical Oceanography of Coastal and Shelf Areas, Johns B (ed.). Elsevier: Amsterdam; 189–266.
Thorne, P. D., Williams, J. J., and Heathershaw A. D (1989). "In situ acoustic measurements of marine gravel threshold and transport",  Sedimentology, 36, pp.61–74
Townsend, A. A. (1976). "The structure of turbulent shear flow."  2nd ed., Cambridge University Press, New York.
Wang, X. K., and Tan, S. K. (2007). "Experimental investigation of the interaction between a plane wall jet and a parallel offset jet." Exp. Fluids. 42(4), pp.551–562.
Wygnanski, I., Katz, Y., and Horev, E. (1992). "On the applicability of various scaling laws to the turbulent wall jet", J. Fluid. Mech. 234, 669–690.
Yaeger M.A. (2009). "Mean flow and turbulence around two series of experimental dikes." MSc. thesis, University of Arizona, Department of Hydrology and Water Resources.
Yoon, S. H., Kim, K. C.,  Kim, D. S., and  Chung, M. K. (1995). "Effect of surface roughness on a turbulent wall-attaching offset jet", Exp. Fluids. 19(1), pp.38–42.