Abstract: Hydrodynamic processes in mangrove forests are closely associated with sediment transport and nutrient cycling. Therefore, understanding the flow characteristics around mangrove vegetation is essential for the conservation and ecological restoration of mangrove wetlands. In this study, three-dimensional turbulent flow around mangrove vegetation under open-channel flow conditions was simulated using OpenFOAM to investigate the effects of mangroves on flow velocity and turbulent kinetic energy distributions. The results are as follows: ① Compared with a single mangrove, a mangrove patch exerts a more pronounced influence on the velocity distribution, expanding the low-velocity zone and enhancing the spatial heterogeneity of the flow field. The overall flow attenuation increases by approximately 131%. ② The mangrove patch significantly increases the turbulent kinetic energy level and promotes the lateral and vertical expansion of high turbulent kinetic energy regions. The overall enhancement is about 45% greater than that induced by a single mangrove. ③ As vegetation configuration transitions from a single mangrove to a mangrove patch, both the extent of the low-velocity zone and the average turbulent kinetic energy increase with the number of trees. However, the rate of increase gradually decreases, exhibiting a non-uniform trend. These findings provide scientific guidance for optimizing vegetation configurations and supporting ecological restoration design in mangrove wetlands.