Experimental investigation of flow characteristics around triangular cylinders in various angular orientations in a tandem configuration

This study investigates the flow around two bluff bodies (BBs) arranged in tandem. The upstream triangular cylinder is tested at three apex and rotation angles, while a square cylinder serves as the downstream body, positioned at varying gap spacings ($G$). The study also includes measurements for single triangular cylinders to demonstrate how the second object alters the flow. The results reveal that both the apex angle and gap spacing have significant effects on the flow characteristics. As the gap decreases from $4D$ to $2D$, the wake structure becomes more complex, with stronger cross-stream velocities and vortical structures near the downstream cylinder. The wake becomes asymmetric in the perpendicular (A90) configuration, and larger gaps ($G=4D$) result in smaller vortices. Gap spacing also affects turbulent kinetic energy, with smaller gaps ($G=2D$) leading to more organized vortex structures, while larger gaps ($G=4D$) amplify the influence of the apex angle on wake dynamics. These findings build on the work of Niegodajew et al. (2024a), enhancing the understanding of tandem bluff body interactions by highlighting the critical roles of the apex angle, orientation, and gap spacing in vortex shedding and turbulence. These results are particularly relevant for ocean engineering, aiding in the design and analysis of offshore structures like subsea pipelines, risers, and breakwaters by informing assessments of hydrodynamic loading, vortex-induced vibrations, and stability.