Flow Hydrodynamics and Associated Kinetic Energy Budgets Produced by Four Piers in Square Configuration

Turbulent flow characteristics around four-pier arrangements are experimentally investigated using particle image velocimetry (PIV). Four wall-mounted piers were arranged in a square configuration at 0 degrees and 90 degrees orientations with different gap-to-pier diameter (G/D) ratios. The study shows an intense horseshow vortex system in front of the pier group at 90 degrees. The kinetic energy increased almost six times with G=D ratio for a square configuration at 90 degrees orientation for a given flow condition. Vortex shedding frequency was studied using spectral analysis and Strouhal number corresponding to dominant frequencies for all cylindrical configurations. High energy vortices were observed in between the piers indicating high turbulence in the region. The square configurations with G/D = 2 at 0 degrees and G/D = 3 at 90 degrees were found to produce intense turbulence in the flow field as compared to other configurations for the given flow condition. The kinetic energy budget showed that the production rate was significantly higher than the dissipation rate. The square configuration with G/D = 1 causes minimal perturbations along the centerline when placed at a 90 degrees orientation. (c) 2023 American Society of Civil Engineers.