Influence of cylindrical obstacle concentration on flow dynamics in channels: a computational approach to optimizing geometric configurations

This study investigates the impact of cylindrical obstacle concentration ( C ) on flow dynamics in low-slope channels using ANSYS Fluent. Cylinders ( D = 12 cm, L = 15 cm) were arranged with varying axial and lateral spacings, producing concentrations from 9 % to 64 %. Simulations under critical flow conditions with a 1 m s −1 inlet velocity employed the VOF method and Kw turbulence model to assess velocity, turbulence, pressure, and shear stress. Results show that increased obstacle concentration enhances energy dissipation, with turbulence intensity decreasing from 0.08 to 0.03–0.05 m 2 s −2 . Wall shear stress rises to 6.5 Pa at 64 % C due to flow constriction, while velocity deficits downstream reduce from 40 %–50 % to 20 %–30 %. These findings underline how obstacle arrangement influences flow resistance and energy loss. It also provide quantitative design insights for improving hydraulic performance in low-slope floodplain environments. These results directly inform flood resilience strategies and infrastructure design by illustrating how controlled obstacle density can enhance energy dissipation and manage flow resistance.