Abstract

This study investigates the turbulent flow properties experimentally in the vicinity of two side-by-side circular cylinders, along with the influence of the third cylinder of the same dimension placed in the upstream and successively in the downstream forming an equilateral triangle. Three-dimensional stereoscopic Particle Image Velocimetry (PIV) was employed to collect the instantaneous velocity data around the arrangements. The study highlights the prime parameters of turbulence such as the mean velocities, Reynolds stresses, turbulent kinetic energy (TKE), quadrant analysis and Q-criteria for vortices, which are responsible for the development of various problems such as scour-hole around the cylindrical pier arrangements, disturbance around industrial and marine structures. The spectral analysis was performed to examine the energy distributions, vortex-shedding frequencies with corresponding Strouhal numbers. Dominant vorticity locations were identified from the contours of Q-criteria. The magnitude of turbulence characteristics was reduced by 15 to 20% (turbulence intensity reduced by 20% and TKE by 15%) when the third cylinder was placed on the upstream of side-by-side cylinder group. Streamlines are also studied to visualize the flow patterns for a better understanding of physics in the presence of the third cylinder. The maximum energy of vortices obtained from the spectrum analysis showed that the vortices generated were less when the third cylinder is placed upstream.

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