Abstract
Centrifugal force at the bend causes the terrain slope at water surface that increases water surface in outer arc and reduces in internal arc. This phenomenon creates adverse pressure gradient inside the arc of cross. As a result, a flow in the transverse direction within the cross is shaped that is called secondary flow. Secondary flow and its interaction with the inertia of the flow, which leads to create a spiral flow causes changes in the topography of the Bed. Understanding the topography of Bed in arcs is essential for specifying scour positions and sediments to determine the best location for the construction of hydraulic structures such as the groin, pond and rivers organizing management. Also in numerical models, one of the most important steps is meshing optimization to achieve the most accurate results and also the least time of analysis of model. Since investigating the numerical sediment transport has been very difficult and research in this area is little; In this study, the most optimal meshing in numerical model is investigated and then tried to be stimulated scouring in the channel bend 90°. For this purpose, the results of the topography of Bed within the arc of channel are obtained using the software FLOW3D and with different turbulence models and compared with experimental results. It should be noted that due to inability of software in the results in perpendicular sections and in direction of flow in the arc, neural network and genetic pattern was used for extracting numerical results in points matching laboratory results. Then flow field in arc is compared with experimental results. The results show the high ability of numerical model FLOW3D in simulating channel with moving Bed. The comparison of turbulence models indicates superiority of turbulence model of LES in investigating changes of Bed in arc channel to other turbulence models.
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References
Bankdari H, Panahian A, Kiamanesh H (2009) Investigating the effect of geometry and distribution of three-dimensional mesh on CFD modeling of turbulent two-phase flows”, the eighth International Congress of Civil Engineering, Shiraz, May 2009
Blankart K, Graf WH (2001) Mean flow and turbulence in open channel bend. J Hydraul Eng 127(10): 835–846
Chen FY, Ikeda S (1997) Horizental separation in shallow open channels with spur dikes. J Hydrosci Hydraul Eng 15: 15–30
Dehghani AA, Ghodsiyan M, Neyshabouri SAAS, Shafie FM (2007) Investigating the effect of flow on the topography of the Bed in 180 degree arc with moving Bed. J Hydraul Irana Hydraul Assoc Summer 2007
Engelund F (1974) Flow and bed topography in channel bends. J Hydraul Div 100(11): 1631–1648
Fazli M, Ghodsiyan M, Salehi N, Seyed AA (2009) Topography changes of Bed in 90-degree bend in different conditions of flow. J Eng Technol Moddares 35: 123–144
Fazli M (2008) Experimental study of scour around the short breakwater in arc, PhD dissertation, Tarbiat Modarres University, Tehran
Ghasemzadeh F (2013) Simulation hydraulic problems in FLOW3D, 2nd edition
Hashemian (2013) The effect of flow rate on the field of open uniform channel downstream speed, convergent and divergent by 90 degree bend, Master’s dissertation, University of Bu Ali Sina, Hamadan
Hersberber D, Schleiss AJ (2002) Influnence of the wall macro-roughness of the scour process in curved channels, Laboratoire de constructions hydrauliques, pp. 121–132
Heydari, Zohre F (2015) Locate and the maximum scour around the open breakwater using the software FLOW-3D, the Tenth International Congress of Civil Engineering, Tabriz University, Tabriz Faculty of Civil Engineering
Ishii C, Asada H, Kishi T (1983) Shape of separation region formed behind a grion of non-overflow type inRivers”; XX IAHR Congress, Moscow, USSR
Mahmoudi and Analya (1998) Investigating the flow pattern in rivers using physical model and compare it with the mathematical model, MA dissertation of Civil of Sanaati Sharif University of Technology, Ahvaz
Mousavi SKAD (2003) Laboratory examination of the impact of chanal curvature radius on the scour of Bed in 90 degree bends, MA dissertation of Department of Civil, Engineering and Technology Faculty, Tarbiat Modarres University
Odgaard AJ (1982) Bed characteristics in alluvial channel bends. J Hydraul Div 108(11):1268–1281
Odgaard AJ, Bergs MA (1988) Flow processes in a curved alluvial channel. Water Resour Res 24(1):45–56
Ouillon S, Dartus D (1997) Three dimensional computation of flow around groynes. J. Hydraul Eng ASCE 123:962–970
Pasiok R, Stilger-Szydlo E (2010) Sediment particles and turbulent flow simulation aroundbridge piers. Arch Civil Mech Eng 8(2):67–79
Peng J, Kawahara Y, Huang GW (1999) Numerical Modeling of Local Scour Around Spur Dikes; 28th IAHR Congress, Graz, Austria
Rozovskii IL (1957) Flow of water in bends of open channels. Academy of Science, Kiev
Salehi SAA, Eqbalzadeh A (2002) Investigating the effect of the flow on topography of the Bed in 180 degree arc”, the sixth international seminar of river, Shahid Chamran University, Ahvaz, 567–574
Tabydany H (2014) The use of averaging method in depth for simulation of flow field and scour around an obstacle in the external arc of channel 90 degree and comparison it with results of the three dimensional analysis
Yaghubiyan H (2014) The impact of the barrier in the external arc on the field of speed in open channel with 90 degree, Master’s dissertation, Bu Ali Sina University in Hamadan, Hamadan
Yen CL, Lee KT (1995) Bed topography and sediment sorting in channel bend with unsteady flow. J Hydraul Eng, 121(8): 591–599
Yen CL, Shin YH (1990) Bed evolution in channl bends. J Hydraul Eng 116(4): 461–473
Zimmermann C, Kennedy JF (1978) Transverse bed slopes in curved alluvialn streams. J Hydraul Div 104(1):1010–1018
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It is appreciated of Hydraulic Laboratory of Tarbiat Modarres University, which Laboratory part of the research is conducted there.
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Mirzaei, H., Heydari, Z. & Fazli, M. The effect of meshing and comparing different turbulence models in predicting the topography of Bed and flow field in the 90 degree bend with moving Bed. Model. Earth Syst. Environ. 3, 799–814 (2017). https://doi.org/10.1007/s40808-017-0336-6
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DOI: https://doi.org/10.1007/s40808-017-0336-6