CFD Numerical Simulation Of Tornado Wind Field And Wind Loads On Structures

As the product of extreme weather such as thunderstorm and super cell, tornadotransforms rapidly in its velocity, is difficult to be monitored and contains awesomepower. Furthermore, it distributes widely in the world and appears more and morefrequently with the deterioration of climate. Human has obtained some experiences ontornado forecast and established relevant prevention mechanism. Even so, it’simpossible for human to uncover the way tornado works thoroughly in the short run. Anumerical simulation method based on CFD was used in our research work to researchwind field of tornado near ground and load effect on structures. The systematic study ontornado in this paper provided a brand new approach for structural tornado-resistantdesign and enriched the wind-resistant theory of structures.The paper established numerical simulation of tornado generating device by meansof CFD code through the analysis of existing laboratory simulation device. The flowfield based on cylindrical coordinate was subdivided into three regions named inflowregion, convection region and outflow region.The paper did a successful simulation of Spencer tornado by use of radarobservation data in1998as the boundary condition in the inlet of numerical model.Mesh generation, turbulence model and boundary conditions were some affectingfactors on tornado simulation, through analyzing them, relevant parameters of CFDsimulation are confirmed.The paper discussed the change of flow field structure with different inlet velocityprofiles and angles of incidence. In concrete terms, the core radius represented thedimension of tornado flow field, meanwhile the maximum tangential velocityrepresented the strength of flow field. Furthermore, the paper attempted to explain theshape shifting of tornado by means of swirl ratio.Some work was done to research the evolution of wind load on lower structures inthe tornado flow field when the structures were placed on different radii and angle ofattack. In addition to this,3D plots of vortex structures were shown to symbolicallydepict the interaction of tornado flow field and structures.