Windborne debris trajectories in tornado-like flow field initiated from a low-rise building

Abstract This paper examines compact debris flight in tornado-like flow fields. The research focuses on physically simulating a specific tornado-like vortex and on investigating windborne debris flight with and without a low-rise building model. The low-rise building model, 1/8th scale with regard to the vortex core radius, was used to initiate the flight of Styrofoam spheres from its top. Debris motion was recorded using three high-speed cameras and data reduction was performed on open-source OpenPTV software. Flow field characterisation showed that including a building model does not considerably affect the averaged flow field but only the local instantaneous flow field. Debris flight analysis shows that the mean flight distance is not affected by the building model, but a change in the initial direction occurs. Comparison between local wind flow field and initial debris velocities shows good agreement, and therefore the variability in initial directions of the debris flight can be attributed to a wind-driven process. To compare with experimental data, experimental data were incorporated into debris flight equations to compute debris motion. Debris trajectories computed from experimental data show strong visual similarities with experimental trajectories and debris flight analysis presents good agreement with experimental data.