Experimental and numerical investigation of flow field characteristics and local scour around trapezoidal artificial reefs

The interactions between artificial reefs (ARs) and water generate a spectrum of flow field effects, which are crucial for both the ecological benefits and structural stability of ARs. Positive flow field effects play a pivotal role in enhancing the ecological utility of ARs; conversely, negative effects can lead to scour around the ARs, thereby jeopardizing their stability. This study investigates local scour around trapezoidal ARs with varying opening ratios (ORs) through the flume experiments. Parallel numerical simulations were conducted to replicate the experimentally observed flow dynamics. Through quantitative analysis, this study identifies specific flow field characteristics that influence the extent of scour around trapezoidal ARs. To optimize design for enhanced ecological functionality and reduced structural risk, we propose a novel comprehensive index that incorporates upwelling, wake, and lateral acceleration flow indices to balance positive and negative flow field effects effectively while optimizing AR opening rate design.