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

Hydraulic structures, particularly water intakes, are often affected by undesirable bedload depositions that can significantly reduce their operational efficiency and lifespan. Based on three-dimensional computational fluid dynamics, this study presents the potential of oblique vertical underflow baffles to redistribute the bedload and mitigate bedload accumulation at critical locations. A straight rectangular channel containing a baffle submerged up to 20% of the flow depth was analyzed under varying discharge rates, baffle alignments, and channel width coverages. The specific flow conditions induced by oblique baffles lead to the generation of a vortex along the trailing edge of the baffle, forming a bedload-free zone on one side of the channel—an effect not observed 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. As discharge increases, the bedload-free zone expands, resulting in greater effectiveness at higher flows—an effect not observed with conventional near-bed bedload control structures. The oblique baffle also remained effective even at a channel width coverage of just 25%, indicating the potential for developing cost-effective designs with minimal structural support. Overall, oblique underflow baffles show potential as a practical and efficient solution for managing bedload transport and deposition, thus protecting critical hydraulic structures.