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http://dx.doi.org/10.12989/was.2018.26.3.115

Numerical investigation of effects of rotating downdraft on tornado-like-vortex characteristics  

Cao, Shuyang (State Key Lab of Disaster Reduction in Civil Engineering, Tongji University)
Wang, Mengen (College of Civil Engineering, Tongji University)
Zhu, Jinwei (Shanghai Urban Construction Design & Research Institute Shanghai)
Cao, Jinxin (State Key Lab of Disaster Reduction in Civil Engineering, Tongji University)
Tamura, Tetsuro (Tokyo Institute of Technology)
Yang, Qingshan (Chongqing University)
Publication Information
Wind and Structures / v.26, no.3, 2018 , pp. 115-128 More about this Journal
Abstract
Appropriate modeling of a tornado-like vortex is a prerequisite when studying the near-ground wind characteristics of a tornado and tornado-induced wind loads on structures. Both Ward- and ISU-type tornado simulators employ guide vanes to induce angular momentum to converge flow in order to generate tornado-like vortices. But in the Ward-type simulator, the guide vanes are mounted near the ground while in the ISU-type they are located at a high position to allow vertical circulation of flow that creates a rotating downdraft to generate a tornado-like vortex. In this study, numerical simulations were performed to reproduce tornado-like vortices using both Ward-type and ISU-type tornado simulators, from which the effects of rotating downdraft on the vortex characteristics were clarified. Particular attention was devoted to the wander of tornado-like vortices, and their dependences on swirl ratio and fetch length were investigated. The present study showed that the dynamic vortex structure depends significantly on the vortex-generating mechanism, although the time-averaged structure remains similar. This feature should be taken into consideration when tornado-like-vortex simulators are utilized to investigate tornado-induced wind forces on structures.
Keywords
Tornado-like vortex; large-eddy simulation; vortex wander; rotating downdraft;
Citations & Related Records
Times Cited By KSCI : 1  (Citation Analysis)
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