Journal of Natural Disaster Science

DEVELOPMENT OF A LABORATORY SIMULATOR FOR SMALL SCALE ATMOSPHERIC VORTICES

Yasushi MITSUTA
Professor
and
Nobutaka MONJI
Associate Professor, Disaster Prevention Research Institute, Kyoto University

(Received 21 Jun., 1984 and in revised form 27 Sept., 1984)

Abstract

A laboratory vortex simulator was developed for the investigation of characteristics of the small scale atmospheric vortices. In the apparatus, circulation is provided by four small fans installed in the circulation chamber. As the inflow from the circulation chamber is turbulent, both the one-cell and two-cell vortices induced in the test chamber are turbulent vortices. Transition of a vortex from a one-cell to two-cell structure occurs throughout the whole convergence layer within a small swirl ratio range near unity. The maximum horizontal velocity appears close to ground surface. The height of the maximum velocity seems to be insensitive to the swirl ratio. The results obtained are compared with those obtained with the Ward type simulators developed in the United States.

Key words

tornado, laboratory simulator, vortex