Numerical study on debris' dynamics in a tornado-like vortex

对龙卷风涡流中碎片的运动轨迹进行了研究。采用大涡模拟方法模拟了龙卷风类旋涡的一系列非定常流场，并对旋涡内部的风特性进行了研究。通过以往龙卷风灾害的记录，对造成建筑物破坏的碎片进行了检查，并检测了飞行碎片的空气动力学参数范围。通过风洞试验研究了日本陶瓷屋面瓷砖川原的空气动力特性。通过与方板、球体等简单形状物体的气动特性进行比较，考察了卡瓦拉的气动特性。利用不同的旋涡强度、大小、移动速度或释放高度以及碎片的气动参数，对碎片在旋涡中的飞行轨迹进行了数值计算。得到了碎屑最大速度的统计和分布。

A study on the trajectory of flying debris in a tornado-like vortex was carried out. A series of unsteady flow fields of tornado-like vortex was generated by Large Eddy Simulation and wind characteristics in the vortex were investigated. Debris resulting building damage was examined by the records of past tornado disasters and the range of aerodynamic parameter of flying debris was detected. The aerodynamic characteristics of kawara, Japanese ceramic roof tile, was also investigated by wind tunnel test. The characteristics of aerodynamics of kawara was examined by comparing with those of simple shape objects such as square plate or sphere. The trajectories of flying debris in the vortex were computed numerically using various condition of vortex strength, size, traveling speed or release height and aerodynamic parameters of debris. The statistics and the distributions of maximum speed of debris were obtained.