Suction Vortices, Spiral Breakdown and Multiple Vortices in Tornadoes

众所周知，龙卷风有时由一个主涡和几个卫星涡组成。 人们怀疑，龙卷风造成的大部分风的变化和极端破坏可能是由于这些卫星涡旋。 在这项研究中，首席研究员将利用经过良好测试的直接数值模拟来研究卫星涡流。 研究的目的是了解卫星涡的特性，特别是卫星涡风速与大涡风速的比值。 控制较大涡旋的物理现象是众所周知的，在一个完整的雷暴模式中更适合模拟。 这项研究将集中在一个系统的，高分辨率的调查龙卷风漩涡的下部，这将是很难做到的雷暴模型。更广泛的影响如下。 首先，了解卫星涡旋中风速的频率和分布，将改善龙卷风的社会问题和风险管理。 第二，卫星涡流强度的一个限制因素是螺旋涡流破裂，这是流体工程感兴趣的现象。 涡破裂的工程利益将受到影响的模拟和分析。

Tornadoes are known to sometimes consist of a main vortex and several satellite vortices. It is suspected that much of the wind variability and extreme damage from tornadoes may be attributable to these satellite vortices. In this research, the Principal Investigator will utilize a well tested direct numerical simulation to study satellite vortices. The purpose of the research is to understand the characteristics of the satellite vortices and especially to investigate the ratio of the wind speed in the satellite vortex to the wind speed in the larger vortex. The physics controlling the larger vortex are somewhat well known and are more amenable for simulation in a complete thunderstorm model. This research will focus on a systematic, high-resolution investigation of the lower part of a tornado vortex, which would be difficult to do with a thunderstorm model. The broader impacts are as follows. First, societal issues and risk management for tornadoes will be improved with knowledge of the frequency and distribution of wind speeds in satellite vortices. Second, a limiting factor in satellite vortex intensity is the spiral vortex breakdown, a phenomenon of interest to fluid engineering. The engineering interest in vortex breakdown will be impacted by the simulations and analysis.