A laboratory study of double eye-walled structure of typhoon under the environment of background vorticity
Date Issued
2009
Date
2009
Author(s)
Kuo, Shu-Hao
Abstract
In this study, the investigation of the double eye wall typhoon by means of hydraulic experiments has been conducted. Similar researches have not been observed in open literatures yet. Provide background vorticity by rotating sink, and produces A typhoon-like vortex vortex was produced under appropriated analog conditions in a rotating tank. By rapid-changing upper flow rate from 58.3 cm3s-1 (siphone) to 116.6 cm3s-1 (siphoge+pump), the changes of flow field changes were observed and measured. Results of experiments show that the appearance of double eye wall is due to the strengthening of vortex core affected by the increasing of upward flow. The sudden speed-up of horizontal circular flow around the vortex core leads to a sharp increase of inward pressure gradient. In order to maintain the cyclostrophic balance, centrifugal force will be increased resulting in the increasing of velocity of circular flow around vortex core. When the upward moving vortex core reaches the free surface, part of the upward flow will move outwardly and downward to the boundary layer of the bottom plate. Part of the downward flow will enters the vortex core inwardly, the rest will move outwardly and turn up around the vortex core. A double eye-walled structure is thus formed. Finally, inner eye wall disappears gradually due the short of fluid support from the boundary layer. Because of the cyclostrophic balance the outer eye wall will take over the inner one to reform a single eye-walled structure.
Subjects
Rotating tank
Double eye wall
Typhoon
Coriolis effect
Particle Image Velocimetr(PIV)
Type
thesis
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