Mathematical Modelling of Sewage Overflow Through Pipe-Manhole Drainage Sewer Systems Using CFD: A Case of Mbale City, Eastern Uganda
The major objective of this study was to design a model to optimize sewage flow through pipe-manhole drainage systems using Computational Fluid Dynamics (CFD). Multi-phase flows like two-phase flow in transport pipes is a common occurrence in many industrial applications such as sewage, water, oil, gas transportation and power generation. Accurate prediction of fluid velocity and pressure drop is of utmost importance to ensure effective design and operation of fluid transport systems. Numerical simulations were performed at different pipe inclinations and fluid flow velocities. A two-dimensional pipe of 0.5 m in diameter and 20 m long was used with a Standard k−ε turbulence and the volume of fraction (VOF) free surface model to solve the turbulent mixture flow of air and water. The CFD approach is based on the Navier-Stokes equations. Results show that the flow pattern behaviour and numerical values of liquid velocities and pressure drop compare reasonably well. It is concluded that the most effective way to optimize a sewer network system in order to minimize the overflows through Pipe-manhole drainage system for Mbale Municipality conditions is by considering minimum and maximum sewer velocities in the range 0.67 ms−1 to 5.5 ms−1 respectively, sewer diameters, slope gradients for optimal sewer design and expanding the number of sewer network connections of household, municipal and industries.
Afshar, M. and Rohani, M. (2012). Optimal design of sewer networks using cellular automata-based hybrid methods: Discrete and continuous approaches. Engineering Optimization, 44(1):1–22.
Afshar, M., Shahidi, M., Rohani, M., and Sargolzaei, M. (2011). Application of cellular automata to sewer network optimization problems. Scientia Iranica, 18(3):304–312.
Afshar, M., Zaheri, M., and Kim, J. H. (2016). Improving the efficiency of cellular automata for sewer network design optimization problems using adaptive refinement. Procedia Engineering, 154:1439–1447.
Akgiray, O. (2004). Simple formulae for velocity, depth of flow, and slope calculations in partially filled circular¨ pipes. Environmental engineering science, 21(3):371–385.
Batchelor, C. K. and Batchelor, G. (2000). An introduction to fluid dynamics. Cambridge University Press.
Beg, M., Carvalho, R., Lopes, P., Leandro, J., Melo, N. (2016). Numerical Investigation of the Flow Field inside a Manhole-Pipe Drainage System. In Crookston B. & Tullis B. (Eds.), Hydraulic Structures and Water System Management. 6th IAHR International Symposium on Hydraulic Structures, Portland, OR, 27-30 June (pp. 61-71). doi: 10.15142/T370628160853
Beg, M. N. A., Carvalho, R. F., and Leandro, J. (2017). Comparison of flow hydraulics in different manhole types. In Managing Water for Sustainable Development: Learning from the past for the future: Proceedings of the 37th IAHR World Congress, volume 6865, pages 4212–4221.
Brackbill, J. U., Kothe, D. B., and Zemach, C. (1992). A continuum method for modeling surface tension. Journal of computational physics, 100(2):335–354.
Chen, Z., Han, S., Zhou, F.-Y., and Wang, K. (2013). A cfd modeling approach for municipal sewer system design optimization to minimize emissions into receiving water body. Water resources management, 27(7):2053–2069.
Esemu, N. J., Masanja, V. G., Nampala, H., Lwanyaga, J. D., Awichi, R. O., and Semwogerere, T. (2020). An Application of Computational Fluid Dynamics to Optimize Municipal Sewage Networks; A Case of Tororo Municipality, Eastern Uganda. Journal of Advances in Mathematics, 18(2020):18–27.
Greenshields, C. (2019). The OpenFOAM foundation user guide 7.0. The OpenFOAM Foundation Ltd: London, United Kingdom, 10th July.
Haghighi, A. and Bakhshipour, A. E. (2012). Optimization of sewer networks using an adaptive genetic algorithm. Water resources management, 26(12): 3441–3456.
Han, W. and Reddy, B. D. (2012). Plasticity: mathematical theory and numerical analysis (Volume 9). Springer Science & Business Media.
Hirt, C. W. and Nichols, B. D. (1981). Volume of fluid (VOF) method for the dynamics of free boundaries. Journal of computational physics, 39(1):201–225.
Jasak, H. (1996). Error analysis and estimation for the finite volume method with applications to fluid flows. PhD Thesis. University of London
Lopes, P., Leandro, J., and Carvalho, R. (2018). Numerical procedure for free-surface detection using a volume-of-fluid model. Journal of Hydro-Environment Research, 21: 43–51.
Moeini, R. and Afshar, M. (2017). Arc based ant colony optimization algorithm for optimal design of gravitational sewer networks. Ain Shams Engineering Journal, 8(2): 207–223.
Muwanga, J. F. S. (2015). Management of sewage in urban areas by national water and sewerage corporation. Value for Money Audit Report. Kampala, UG: Office of The Auditor General, The Republic of Uganda.
MWE. (2018). Water and environment sector performance report.
Park, M. A., Loseille, A., Krakos, J., Michal, T. R., and Alonso, J. J. (2016). Unstructured grid adaptation: status, potential impacts, and recommended investments towards CFD 2030. In 46th AIAA fluid dynamics conference, page 3323.
Petit-Boix, A., Roige, N., de la Fuente, A., Pujadas, P., Gabarrell, X., Rieradevall, J., and Josa, A. (2016). Integrated structural analysis and life cycle assessment of equivalent trench-pipe systems for sewerage. Water resources management, 30(3):1117–1130.
Rusche, H. (2002). Computational fluid dynamics of dispersed two-phase flows at high phase fractions. PhD thesis, University of London.
Swamee, P. K. and Sharma, A. K. (2013). Design of a pumping main considering pipeline failure. Water resources management, 27(1):199–207.
Zaheri, M., Ghanbari, R., and Afshar, M. (2019). A two-phase simulation–optimization cellular automata method for sewer network design optimization. Engineering Optimization.
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