Aerodynamic characteristics of a surface mounted prism of small aspect ratio immersed in atmospheric boundary layer.

This article investigates the wake dynamics and aerodynamic forces of surface-mounted finite-height square prisms with small aspect ratios (AR = height/width) immersed in a thick atmospheric boundary layer (ABL) using three-dimensional large-eddy simulations (LES). The study compares prisms with AR = 1 (cube) and AR = 0.5, revealing that a decrease in aspect ratio leads to contraction of the shear layer and recirculation bubble, a stronger horseshoe vortex closer to the wall, and altered wake morphology including inner vortex pairs with opposite vorticity in the wake. The atmospheric boundary layer causes a reduction in average drag force and weakens wake periodicity, with proper orthogonal decomposition (POD) analysis showing more chaotic wake behavior and suppressed vortex shedding modes for the lower AR prism. These findings enhance understanding of flow structures and forces on low-aspect-ratio prisms under realistic turbulent boundary layer conditions, relevant to engineering applications, and suggest further research on turbulence intensity effects and wake dynamics is needed.