Study of the Scour and Turbulent Flow Characteristics around Unsubmerged I-Head and T-Head Groynes in Series

Abstract

Abstract

Groynes play a crucial role in stream bank protection and erosion mitigation, offering environmental sustainability and benefits such as enhanced navigation and aquatic biodiversity. However, research on groynes, particularly those with unconventional head shapes, remains limited. This study addresses the existing gap by presenting the experimental results on flow dynamics and scour patterns around a series of I-head groynes (IHGs) and T-head groynes (THGs) under clear-water scour conditions in a straight mobile sediment bed channel. The findings revealed distinct behaviors in scour patterns and flow characteristics between IHGs and THGs. Maximum scour depths occurred near the tip of upstream groynes, with similar magnitudes observed in both types of groyne series. The streamwise velocity decreased significantly throughout the groyne field regions for both IHG and THG, indicating effective bank protection. Maximum negative vertical flow velocities aligned with locations of maximum equilibrium scour. The downstream groyne fields in both cases exhibited lower turbulent kinetic energy and bed shear stresses, implying reduced sediment transport and stabilized flow. Absence of significant stresses on downstream groyne fields suggests flow redistribution and turbulence decay, indicating a better stabilized flow. The turbulence anisotropy study further revealed how variations in turbulence structures influence the scour and deposition processes, offering deeper insight into the flow–sediment interactions around groynes. These findings provide a better insight in design considerations, highlighting the potential of THGs in enhancing structural performance and efficiency. Additionally, this study contributes to understanding flow dynamics, sediment transport processes, and groyne performance, serving as a benchmark for numerical simulations. The insights aid in optimizing groyne design and selection based on specific field requirements, thereby benefiting river system management regarding navigation, bank protection, and ecology.