Numerical modeling of flow dynamics around L-shaped and T-shaped dikes with varying geometric configurations and wing arrangements

Impermeable dikes are crucial for riverbank protection and significantly affect flow dynamics, including velocity and turbulence characteristics. The spacing between the dikes, their shape, submergence level, overall geometry, and permeability all have a profound impact on river morphology. This study investigated the effects of dike shape and geometry on flow velocity and turbulence using a numerical approach. FLUENT (ANSYS), a CFD software program, was applied to simulate the steady flow around an impermeable dike. Sensitivity analyses were conducted to determine the appropriate turbulence model and mesh resolution. Based on these analyses, the rigid lid assumption (RLA) method with the \(k-\varepsilon\) $k-\epsilon$ turbulence model was selected to capture the flow characteristics. The accuracy of the model was confirmed through a physical experiment conducted in a rectangular open channel. The findings indicated that the numerical model accurately replicated flow dynamics in both the mainstream and the dike field. Notably, the highest mean velocity and turbulence were observed around the impermeable dikes (I-shaped, L-shaped, T-shaped). The position of the inflection points varied based on the shape of the impermeable dike and its wing type. The T-shaped dike with a full-length cylindrical wing was the most effective, reducing flow velocity by 75% and turbulent kinetic energy by 26%. These results have practical implications for flood management strategies, enhancing public safety, environmental protection, and economic efficiency. By providing a deeper understanding of optimal dike configurations, this research supports informed decision-making in river management.