Near surface experimental exploration of tornado vortices

It is shown that at low swirls, tornado vortices are unstable and highly characterized by wandering. A qualitative investigation of the vortex wandering and a preliminary estimation of the effect of vortex wandering on time-averaged pressures are performed. Also, surface pressure data are used to examine the Reynolds number dependency of the flow. A clear demarcation of the surface layer behavior inside versus outside of the vortex core is observed. Normalizing axial profiles of core radii and tangential velocities in the region outside of the vortex core with the core radius and height of the maximum tangential velocity suggests self-similarity of the flow with future implications for empirical modeling. Axial profiles of the radial velocity are used to determine the vortex structure at various swirl ratios.