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AUTHOR(S): Filbert Akabwai, Verdiana Grace Masanja, Joseph Ddumba Lwanyaga, Twaibu Semwogerere, Asaph Keikara Muhumuza
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ABSTRACT The optimal and sustainable performance of sewer networks is of utmost importance in urban drainage systems. Efficient operation of urban sewer networks is increasingly challenged by sediment deposition, climate variability and rapid urbanization. This study develops and validates a Computational Fluid Dynamics (CFD) model to analyze flow dynamics and sediment transport behavior in selected sewer sections of Tororo Municipality, Eastern Uganda. A two-dimensional (2D) multiphase model was implemented using OpenFOAM’s interFoam solver with the SST k–ω turbulence closure. The Reynolds-Averaged Navier–Stokes (RANS) equations were solved under incompressible flow assumptions, coupled with Volume of Fluid (VOF) formulation for phase tracking. This study analysed the hydro mechanical properties of flow in sewer pipes at different flow speed and their effect on sediment flow capacity by use of two dimensional numerical simulation of flow field using Computation Fluid Dynamics (CFD). Mesh independence testing, time-step sensitivity analysis, and Courant–Friedrichs–Lewy (CFL) stability verification were performed to ensure numerical robustness. The study proposes revised self-cleansing design criteria based on minimum velocity and minimum bed shear stress thresholds. A conservative minimum bed shear stress of 2 N/m² is recommended for cohesive sediments with roughness height ks = 1.2 mm. Results show that optimal sediment transport occurs near inlet velocities of 1.0 m/s, balancing entrainment efficiency and excessive turbulence. The study highlighted the predictive capacity of CFD for sewer optimization while explicitly quantifying limitations associated with 2D modeling relative to three-dimensional (3D) flow behavior. |
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KEYWORDS Computational Fluid Dynamics (CFD), Sewers flows, Sediment transport, Mathematical model |
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Cite this paper Filbert Akabwai, Verdiana Grace Masanja, Joseph Ddumba Lwanyaga, Twaibu Semwogerere, Asaph Keikara Muhumuza. (2026) Modelling Flow and Sediment Transport in Urban Sewer Systems Using Computational Fluid Dynamics: Case of Tororo Municipality, Eastern Uganda. International Journal of Mechanical Engineering, 11, 23-35 |
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