A perspective on the aerodynamics and aeroelasticity of tapering: Partial reattachment

Abstract Tapering is a common morphological modification to ensure the stability of civil structures, especially as more and more high-rise buildings push the skyline of modern cities. However, the aerodynamics, aeroelasticity, and fluid-structure-interaction of tapering remain far from been fully understood. Through wind tunnel tests, the present work offers some notable observations on the effects of tapering, specifically considering different wind attack angles, wind velocities, and structural rigidities. A novel phenomenon unique to tapering is discovered and termed as partial reattachment. It depicts the partial reattachment of a shear layer onto a tapered structural face, which suppresses vortex shedding in reattached regions and forms a separation envelope. It also propagates from structural base to the free end with an increasing wind attack angle, and ultimately transforms into complete reattachment. Consequently, behavioral bi-polarities in force, vortex shedding characteristics, and cross-point correlation are observed. Aeroelastically, tapering promotes the unsteady effect and the VIV-galloping interaction near the free-end, making the prism more susceptible to wind-induced vibrations. With aeroelasticity, partial reattachment also introduces a discontinuous vortex shedding phenomenon, which is subjected to an intensity demarcation.