The role of transverse inclination on the flow phenomenology around cantilevered prisms and the tripole wake mode

Abstract

This work conducted wind tunnel experiments and high-fidelity numerical simulations to study the flow phenomenology around and aerodynamic characteristics of a transversely inclined cantilever prism—a highly probable but unattended configuration when inclined civil structures are subjected to changing angle of attack. The velocity field, stream and spanwise vorticity, Q-criterion vortex structures, aerodynamic force and spectra, surface pressures, and shear layer morphology have been comprehensively analyzed. Results showed significant deviations from the vertical prism, deeming many classical observations on the prism wake untransferable to the inclined cases. The underlying flow phenomenology was subsequently clarified. Transverse inclination induces a fundamentally different, asymmetric wake morphology, especially near the fix- and free-end, suppressing the horseshoe vortices and intensifying near-wake turbulence. The prism base also experiences a remarkable intensification of wind load and vortical dynamics. The suppression of vortical activities on the near-wind side of the fix-end also gives rise to a new wake morphology – the tripole mode – unique to transverse inclination. Moreover, transversely inclined prisms experience different crosswind loads when angle of attack reverse in sign, which is attributed to changes in shear layer curvature. This work’s conclusions partially fill the gap in the fluid mechanics of inclined prisms and, more importantly, highlight the extra cautions needed for engineering applications involving inclined structures.