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Numerical Investigation of Baffle Effect on the Flow in a Rectangular Primary Sedimentation Tank

Authors: M. Shahrokhi, F. Rostami, M.A. Md Said, S. Syafalni


It is essential to have a uniform and calm flow field for a settling tank to have high performance. In general, the recirculation zones always occurred in sedimentation tanks. The presence of these regions may have different effects. The nonuniformity of the velocity field, the short-circuiting at the surface and the motion of the jet at the bed of the tank that occurs because of the recirculation in the sedimentation layer, are affected by the geometry of the tank. There are some ways to decrease the size of these dead zones, which would increase the performance. One of the ways is to use a suitable baffle configuration. In this study, the presence of baffle with different position has been investigated by a finite volume method, with VOF (Volume of Fluid) model. Besides, the k-ε turbulence model is used in the numerical calculations. The results indicate that the best position of the baffle is obtained when the volume of the recirculation region is minimized or is divided to smaller part and the flow field trend to be uniform in the settling zone.

Keywords: Sedimentation tanks, Baffle, Numerical Modeling, VOF, Circulation Zone

Digital Object Identifier (DOI):

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[1] Silveston, P.L., J.F. Cordoba-Molina, and R.R. Hudgins, "The use of flow contraction to improve clarifier performance". Water Science and Technology, 13 1981: p. 385-394.
[2] Hamlan, M.J. and A.H.A. Wahab, "Settling Characteristics of Sewage in Density Currents". Water Research, 4 1970: p. 251-271.
[3] Crosby, R.M., Evaluation of the Hydraulic characteristics of activated sludge secondary clarifiers. 1984, Environmental Protection Agency,Office of Research and Development: Washington, D.C. U.S. p. 84-131.
[4] Bretscher, U., P. Krebs, and W.H. Hager, "Improvement of flow in final settling tanks". J. Enviromental Engineering, ASCE, 118 1992.(3): p. 307-321.
[5] Zhou, S., J. McCorquodale, and Z. Vitasovic, "Influences of density on circular clarifiers with baffles". Journal of Environmental Engineering, ASCE, 118 1992.(6): p. 829-847.
[6] Huggins, D.L., R.H. Piedrahita, and T. Rumsey, "Analysis of sediment transport modeling using computational fluid dynamics (CFD) for aquaculture raceways". Aquacult. Eng., 31 2005: p. 277-293.
[7] Fan, L., et al., "Numerical simulation of secondary sedimentation tank for urban wastewater". J. Chin. Inst. Chem. Eng., 38 2007: p. 425-433.
[8] Tamayol, A., B. Firoozabadi, and G. Ahmadi, "Effects of Inlet Position and Baffle Configuration on Hydraulic Performance of Primary Settling Tanks". Journal of Hydraulic Engineering, ASCE., 134 2008.(7): p. 1004-1009.
[9] Goula, A.M., et al., " A CFD methodology for the design of sedimentation tanks in potable water treatment case study: the influence of a feed flow control baffle". Chem. Eng. J., 140 2007: p. 110-121.
[10] Sammarraee, M.A. and A. Chan, "Large-eddy simulations of particle sedimentation in a longitudinal sedimentation basin of a water treatment plant. Part 2: The effects of baffles". Chemical Engineering Journal 152 2009: p. 315-321.
[11] Hirt, C.W. and B.D. Nichols, "Volume of Fluid (VOF) Method for the Dynamics of Free Boundaries". J. Comp. Phys., 39 1981: p. 201-225.
[12] Hirt, C.W. and J.M. Sicilian, A Porosity Technique for the Definition of Obstacles in Rectangular Cell Meshes, in Fourth International Conf. Ship Hydro. 1985, National Academy of Science: Washington, DC. p. 1- 19.
[13] Harlow, F.H. and P.I. Nakayama, "Turbulence Transport Equations". Phys. of Fluids, 10 1967.(11): p. 2323-2333.
[14] Svendsen, I. and J. Kirby, Numerical study of a turbulent hydraulic jump, in 17th ASCE Engineering Mechanics Conference. 2004: University of Delaware, Newmark, DE.
[15] FlowScience, Flow-3D user manual. 2009.
[16] Imam, E., J.A. McCorquodale, and J.K. Bewtra, "Numerical Modeling of Sedimentation Tanks". Journal of Hydraulic Engineering, ASCE., 109 1983.(12): p. 1740-1754.
[17] Hirt, C.W., Identification and Treatment of Stiff Bubble Problems. 1992, Flow Science Inc.