Hydrodynamics of inclined cylinder arrays: Effects of streamlining angle and vegetation density

Earlier studies have independently examined the hydrodynamic effects of either streamlining angle or vegetation density in model vegetation canopies. However, the coupled influence of these two parameters on the three-dimensional hydrodynamics of infinite arrays of inclined cylinders remains insufficiently understood. This study addresses this gap by employing large eddy simulations to investigate the interplay between streamlining angle and vegetation density in periodic cylinder arrays that mimic aquatic vegetation. The simulations reveal that increasing vegetation density elevates drag, torque, and flow unsteadiness, especially near the bed. The streamlining angle exerts a strong influence on spanwise asymmetry, vortex shedding characteristics, and vertical wake structure. Drag force stability improves at moderate inclinations, while high angles intensify wake three-dimensionality and vertical momentum transport. The Strouhal number and vortex shedding frequency exhibit nonlinear sensitivity to both inclination and spacing, diverging from trends observed in isolated or upright cylinders. Pressure and velocity distributions demonstrate significant vertical heterogeneity, emphasizing the importance of three-dimensional flow modeling. By systematically varying both inclination and spacing in an infinite array context, this study provides the first comprehensive framework to evaluate fluid-vegetation interactions relevant to flexible aquatic canopies.