CFD Study on the Influence of Oblique Underflow Baffles on Bedload Transport in Rectangular Channels

Hydraulic structures, particularly water intake systems, are often affected by unwanted bedload depositions, which can significantly reduce their operational efficiency and lifespan. This numerical study presents the potential of using oblique vertical underflow baffles in redistributing the bedload and mitigating bedload accumulations at desired locations. In this study, a straight rectangular channel containing an underflow baffle submerged up to 20% of the water depth was analyzed in a three-dimensional computational fluid dynamics model while varying the discharge, baffle alignment, and channel width coverage. The specific flow conditions induced by the oblique underflow baffles generates a vortex on one side of the channel following the trailing edge of the baffle, where a bedload free zone is created, unlike the case with an orthogonal baffle. This phenomenon offers a potential strategy for managing bedload movement in channels and sluices, providing a means to prevent undesirable bedload depositions and to help operating hydraulic structures efficiently. Furthermore, increasing discharge expands the bedload free zone, and the oblique baffle remains significantly effective even for channel width coverage of just 25%, which indicates the potential of cost-effective designs with limited structural supports. Moreover, this study demonstrates that oblique underflow baffles can effectively guide bedload transport within the channel cross-section, presenting a practical and efficient approach for bedload management and safeguarding intake and similar hydraulic structures.