A Laboratory Investigation of the Structure of Multiple Vortices

Abstract

The structure of the multiple vortices formed in small scale atmospheric vortices is studied in a laboratory experiment.

The Structure of Polygonal Eye of a Typhoon

“…Several investigators have studied in laboratory experiments (Monji, 1985) and in theoretical experiments (Snow, 1978;Staley and Gall, 1979). Snow (1978) investigated the "inertial" st ability of vortex with an "internal shear layer"; the other hand, Staley and Gall (1979) also studied the barotropic instability and found the wave number of the order of 1 to 5 are significantly unstable.…”

Numerical study of turbulent flow fields and the similarity of tornado vortices using large-eddy simulations

“…For the laboratory simulators used by Church et al (1979), Monji (1985), Mishra et al (2008), Matsui and Tamura (2009) and Tari et al (2010) and the numerical simulators used by Rotunno (1977), Wilson and Rotunno (1986), and Ishihara et al (2011), the swirl ratio has historically been defined as the ratio of the angular …”

“…Concurrent with the expansion of the core, the inner downdraft penetrates to the ground surface; a family of several secondary vortices rotating around the main vortex is evident. Church et al (1979) and Monji (1985) reported the vortex type as a function of the Reynolds number and the swirl ratio. It was concluded that the vortex type depends slightly on the Reynolds number; this dependency decreases for higher Reynolds numbers.…”

“…The maximum horizontal velocity appeared close to the ground surface; moreover, the height of the maximum velocity was found to be insensitive to the swirl ratio. Monji (1985) investigated the structure of multiple vortices using a guide vane simulator. It was found that the structure of the subsidiary vortex varies with height and that the translational velocity of the subsidiary vortex is sligless than the mean tangential velocity of the parent vortex at high levels.…”

Physical simulation of a single-celled tornado-like vortex, Part A: Flow field characterization

“…The Tornado Vortex Chamber at Kyoto University (Monji, 1985) provided circulation by means of four fans operating in an annular region surrounding the inflow, but these fans produced unwanted turbulence within the simulator at all swirl ratios. Rothfusz (1986) provided circulation that could be varied as a function of height in a modified Ward simulator with a three-tier system of vanes.…”