Assessment of Inlet Baffle Configurations on Hydraulic Characteristics of a Rectangular Gravity Separator Using CFD
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Abstract
Rectangular gravity separators are commonly used within wastewater treatment systems to remove fat, oil, and grease from water. The performance of these vessels is dependent to a great extent on the uniformity of the flow, since turbulence and recirculating eddies tend to break drops together, thus reducing the separation efficiency. Therefore, adding the inlet baffle is a feasible way to improve the hydraulic stability in the separator. To simulate the characteristics of flow in the gravity separator tanks, a two-dimensional computational fluid dynamics (CFD) model of a single-phase flow has been developed with Flow-3D (v11.04). The numerical model employed was based on the Finite Volume Method (FVM), used the Volume of Fluid (VOF) technique to simulate the free surface behavior, and implemented an RNG k–ε turbulence model. Flow behavior was analyzed using three parameters: the velocity standard deviation, which denotes the flow uniformity, the percentage of recirculation zones corresponding to mixing and stability, and kinetic energy distribution. The results showed that the baffle with two apertures provided the best hydraulic performance by minimizing velocity fluctuations and cross-flowing and also kinetic energy distribution. Thus, this arrangement was determined to be the most effective design in promoting the flow stability and separation performance inside a rectangular gravity separator.
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Acharya, T., Casimiro, L., 2020. Evaluation of flow characteristics in an onshore horizontal separator using computational fluid dynamics. Journal of Ocean Engineering and Science, 5, pp. 261-268. https://doi.org/10.1016/j.joes.
AL-Yacouby, A. M., Ahmed, M. M., 2022. A numerical study on the effects of perforated and imperforate baffles on the sloshing pressure of a rectangular tank. Journal of Marine Science and Engineering, 10, P. 1335. https://doi.org/10.3390/jmse10101335.
Azimi, H., Shabanlou, S., 2020. U-shaped channels along the side weir for subcritical and supercritical flow regimes. ISH Journal of Hydraulic Engineering, 26, pp. 365-375. https://doi.org/10.1080/09715010.2018.1493706.
Chen, S. Y., Shimizu, S., Watanabe, H., 2024. Adjoint-based topology optimization for hydraulic performance improvement in double-suction volute pump. In: Fluids Engineering Division Summer Meeting, American Society of Mechanical Engineers, V001T01A013. https://doi.org/ 10.1115/FEDSM2024-130597.
Efendioglu, A., Mendez, J., Turkoglu, H., 2014. The numerical analysis of the flow and separation efficiency of a two-phase horizontal oil-gas separator with an inlet diverter and perforated plates. Advances in Fluid Mechanics, 10, P. 133. https://doi.org/10.2495/AFM140121.
Fang, R., Sondak, D., Protopapas, P., Succi, S., 2020. Neural network models for the anisotropic Reynolds stress tensor in turbulent channel flow. Journal of Turbulence, 21, pp. 525-543. https://doi.org/10.1080/14685248.2019.1706742.
Fluent Ink., 2009. ANSYS Fluent 12.0 theory guide. Canonsburg, PA: ANSYS Inc.
Hartal, O., Souabi, S., Chatoui, M., Ettaloui, Z., Madinzi, A., Rifi, S. K., Kurniawan, T. A., Anouzla, A., 2023. Contamination reduction of vegetable oil refinery wastewater using innovative acid and basic chemical flotation processes. Preprint. https://doi.org/10.21203/rs.3.rs-3146896/v1.
He, X., De Los Reyes III, F. L., Ducoste, J. J., 2017. A critical review of fat, oil, and grease (FOG) in sewer collection systems: Challenges and control. Critical Reviews in Environmental Science and Technology, 47, pp. 1191-1217.
Hirt, C., Sicilian, J., 1985. A porosity technique for the definition of obstacles in rectangular cell meshes. In: Proceedings of the 4th International Conference on Numerical Ship Hydrodynamics.
Hirt, C. W., Nichols, B. D., 1981. Volume of fluid (VOF) method for the dynamics of free boundaries. Journal of Computational Physics, 39, pp. 201-225. https://doi.org/10.1016/0021-9991(81)90145-5.
Hussein, H. A., Abdullah, R., Harun, S., Abdulkhaleq, M., 2013. Numerical model of baffle location effect on flow pattern in oil and water gravity separator tanks. World Applied Sciences Journal, 26, pp. 1351-1356 . https://doi.org/10.5829/idosi.wasj.2013.26.10.1239.
Hussein, H. A., Abdullah, R., Md Said, M. A., 2015. Computational investigation of inlet baffle height on the flow in a rectangular oil/water separator tanks. Applied Mechanics and Materials, 802, pp. 587–592. https://doi.org/10.4028/www.scientific.net/AMM.802.587.
Jameel, A. T., Muyubi, S. A., Karim, M. I. A., Alam, M. Z., 2011. Removal of oil and grease as emerging pollutants of concern (EPC) in wastewater stream. IIUM Engineering journal, 1. https://doi.org/10.31436/iiumej.v12i4.218.
Keener, K. M., Ducoste, J. J., Holt, L. M., 2008. Properties influencing fat, oil, and grease deposit formation. Water environment research, 80, pp. 2241-2246. https://doi.org/10.2175/193864708X267441.
Kim, S., Kim, H., Jeong, H. S., Kim, Y., 2025. Optimal design of perforated baffles for enhancing oil-water separation performance using genetic algorithms. Results in Engineering, 26, p. 10466. https://doi.org/10.1016/j.rineng.2025.104668.
Laleh, A. P., Svrcek, W. Y., Monnery, W. D., 2012. Design and CFD studies of multiphase separators—a review. The Canadian Journal of Chemical Engineering, 90, pp. 1547-1561.
Li, J.-P., Tang, D.-G., Yi, C., Yan, C., 2022. Data-augmented turbulence modeling by reconstructing Reynolds stress discrepancies for adverse-pressure-gradient flows. Physics of Fluids, 34.
Ma, H., Ma, Z., Zhao, Q., Li, Y., Zhu, K., Zhang, H., Chen, X., 2024. Arrow-shaped patterned microchannel for enhancing droplet coalescence and demulsification of oil-in-water emulsions with high oil content. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 685, P. 133177. https://doi.org/10.1016/j.colsurfa.2024.133177.
Mattsson, J., Hedström, A., Viklander, M., Blecken, G.-T., 2014. Fat, oil, and grease accumulation in sewer systems: comprehensive survey of experiences of Scandinavian municipalities. Journal of environmental engineering, 140, P. 04014003. http://dx.doi.org/10.1061/(ASCE) EE.1943-7870.0000813 .
Mee, C. G., Nor, M. I. M., 2011. Flow pattern in a horizontal primary separator with a perforated baffle. Journal of the Institution of Engineers, Malaysia, 72.
Metcalf, Eddy, A., 2014. Wastewater Engineering Treatment and Resource Recovery. New York: McGraw-Hill Education.
Mir Emad, M., Mazaheri, K., Darbandi, M., 2025. Assessment of algebraic anisotropic turbulent heat flux models using Reynolds stress modeling for simulating film cooling flows. Physics of Fluids, 37. https://doi.org/10.1063/5.0245045.
Mohana, A. A., Roddick, F., Maniam, S., Gao, L., Pramanik, B. K., 2023. Component analysis of fat, oil and grease in wastewater: challenges and opportunities. Analytical Methods, 15, pp. 5112-5128. https://doi.org/10.1039/D3AY01222K.
Nascimento, J. B. D. S., Ferreira, A. D., Vasconcelos, A. L., De Farias Neto, S. R., 2025. Study of the influence of Semi-porous baffles on the three-phase separation efficiency in a horizontal separator vessel via CFD. Journal of Petroleum Science and Technology , 14(3), P. 50.
Nimisha, P., Jayalekshmi, B., Venkataramana, K., 2022. Slosh damping in rectangular liquid tank with additional blockage effects under pitch excitation. Journal of Fluids Engineering, 144, P. 121403. https://doi.org/10.1115/1.4054959.
Roy-Biswas, T., Singh, P., 2025. Volume of fluid approach for modeling nappe flow over hydraulic structures. Physics of Fluids, 37.
Selim, T., Hamed, A. K., Elkiki, M., Eltarabily, M. G., 2024. Numerical investigation of flow characteristics and energy dissipation over piano key and trapezoidal labyrinth weirs under free-flow conditions. Modeling Earth Systems and Environment, 10, pp. 1253-1272. https://doi.org/10.1007/s40808-023-01844-w.
Solov’eva, O. V., Solov’ev, S. A., Yafizov, R. R., Ponikarov, S. I. and Portnov, I. Y., 2021. Influence of design of baffles in a gravity-dynamic separator model on water-oil emulsion separation efficiency. Chemical and Petroleum Engineering, 56, pp. 884–888. https://doi.org/10.1007/s10556-021-00912-1
Shahrokhi, M., Rostami, F., Said, M. A. M., Yazdi, S. R. S., 2012. The effect of number of baffles on the improvement efficiency of primary sedimentation tanks. Applied Mathematical Modelling, 36, pp. 3725-3735. https://doi.org/10.1016/j.apm.2011.11.001.
Torres, C., Borman, D., Sleigh, A., Neeve, D., 2021. Application of three-dimensional CFD VOF to characterize free-surface flow over trapezoidal labyrinth weir and spillway. Journal of Hydraulic Engineering, 147, P. 04021002. https://doi.org/10.1061/(ASCE)HY.1943-7900.0001852.
Tsega, E. G., 2024. Advancing Finite Difference Solutions for Two‐Dimensional Incompressible Navier–Stokes Equations Using Artificial Compressibility Method and Sparse Matrix Computation. Journal of Applied Mathematics, 2024(1), P. 5506715. https://doi.org/10.1155/2024/5506715.
Versteeg, H. K., 2007. An introduction to computational fluid dynamics the finite volume method, 2/E, Pearson Education India.
Wahba, E., 2022. Derivation of the differential continuity equation in an introductory engineering fluid mechanics course. International Journal of Mechanical Engineering Education, 50, pp. 538-547. https://doi.org/10.1177/03064190211014460.
Wilkinson, D., Waldie, B., Nor, M. M., Lee, H. Y., 2000. Baffle plate configurations to enhance separation in horizontal primary separators. Chemical Engineering Journal, 77, pp. 221-226.
Xu, H., Zhou, Y., Daniel, D., Herzog, J., Wang, X., Sick, V., Adera, S., 2023. Droplet attraction and coalescence mechanism on textured oil-impregnated surfaces. Nature Communications, 14, P. 4901. https://pubs.acs.org/doi/10.1021/acsnano.3c07407.
Yakhot, V., Orszag, S. A., 1986. Renormalization group analysis of turbulence. I. Basic theory. Journal of scientific computing, 1(1), pp. 3-51. https://doi.org/10.1007/BF01061452.
Yakhot, V., Orszag, S. A., Thangam, S., Gatski, T., Speziale, C., 1992. Development of turbulence models for shear flows by a double expansion technique. Physics of Fluids A: Fluid Dynamics, 4, pp. 1510-152 0. https://doi.org/10.1063/1.858424.
Yousefelahiyeh, R., Dominic, C. C. S., Ducoste, J., 2017. Modeling fats, oil and grease deposit formation and accumulation in sewer collection systems. Journal of Hydroinformatics, 19, pp. 443-455.
Zhang, Y., Zhang, D., Jiang, H., 2023. Review of Challenges and Opportunities in Turbulence Modeling: A Comparative Analysis of Data-Driven Machine Learning Approaches. Journal of Marine Science and Engineering, 11. https://doi.org/10.3390/su151813384.
Zhu, D., Han, D., He, W., Chen, J., Ji, Y., Tao, P., Gu, Y., 2022. Performance analysis of the separator with inner channels by experiment and CFD-POST. Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 44, pp. 8527-8541. https://doi.org/10.1080/15567036.2022.2118908.