Flow Dynamics Around Permeable Spur Dike in a Rectangular Channel

In this study, numerical simulations were performed to investigate the flow and turbulence characteristics of rectangular spur dikes with varying permeability using the Reynolds stress turbulence model developed by three-dimensional (3-D) numerical code FLUENT (ANSYS). In this research, both permeable and impermeable spur dikes were investigated with varying permeability (25%, 37%, 49%, 62%, and 74%) to show its effect on the flow structure. At z(h)=3.5 cm (where z is the maximum flow depth, and z(h) is mid of flow depth), 3-D flow velocities and depth-averaged velocities were measured in the horizontal plane. Different velocity profiles and contours, turbulent intensities (T.I), and turbulent kinetic energy (TKE) were analyzed at various selected positions. The findings indicate that an increase in the permeability of the spur dikes up to 74% had a reciprocal effect on the mean stream-wise velocity. Moreover, the recirculation regions created within the impermeable spur dike field decreased with increased permeability of spur dikes. The permeable spur dike head showed a significant decrease in T.I, and TKE compared to the impermeable spur dike. Therefore, to protect the spur dike head from severe turbulent flow during floods and reduce the spur dike field's recirculation region, a permeable spur dike is preferred.

Automated summary

The study found that an increase in the permeability of the spur dikes has a reciprocal effect on the mean stream-wise velocity and the recirculation regions created within the impermeable spur dike field decreased with increased permeability. Permeable spur dikes showed a significant decrease in turbulent intensities and turbulent kinetic energy compared to impermeable spur dikes.