Pressure Fields Beneath Tornado-like Vortices

Abstract

Wall static pressure fields beneath tornado-like vortices have been investigated using a vortex generator designed to model tornado-cyclone airflow. The data presented include (a) a series of radial profiles of the mean surface pressure beneath the vortex as a function of swirl, (b) measurements of the magnitude of the greatest pressure deficit to be found under the vortex as a functionof swirl, and (c) a set of measurements of the pressure deficits associated with the individual subsidiary vortices in a multiple vortex system. These data are interpreted to show the development of the model.tornado cyclone from the no-swirl state, and the evolution of its intense vortical core from a one-celled into a two-celled flow. It is shown that the greatest pressure deficits and largest pressure gradients are associated with single-celled vortices. The pressure deficits within the subsidiary vortices are found to be two to three times as great as that at the center of the parent flow. This work provides the background for better physical interpretation of barographic records obtained in actual tornado cyclones, and further supports a model of the evolution of these phenomena that is consistent with doppler radar observations of natural tornado cyclones.