Effects of Artificial Reef Array Configuration on Turbulent Flow: PIV Experiment and Numerical Simulation

Complex turbulent flow structures are formed within and around box-type artificial reefs (ARs). This study utilizes Particle Image Velocimetry (PIV) and numerical simulation to investigate the flow field within and around ARs of various configurations, such as single- and dual-row arrays. It was found that a small space between reefs causes loading to concentrate on the first reef, while a large space enhances vortex intensity and reduces interference among reefs and promotes vortex development within individual reefs. An optimal space may enlarge the recirculation zone, increase vortex numbers and size, alter the flow distribution, and intensify turbulence, ultimately reshaping the flow characteristics at the reef array. The experimental data show that vortices within ARs attain their maximum strength at an overall reef length to height ratio (L_r/h_r) of 3 and reef width to height ratio (W_r/h_r) of 0.68. A further increase in L_r/h_r weakens the dipole, while an increase in W_r/h_r expands the area of high-vorticity and strong turbulence behind the stoss-face openings. These findings provide new insights for the optimum layout of artificial reefs for coastal defense design.