Collaborative Research: Dynamical Processes Driving the Genesis and Maintenance of Tornadic Vortices

合作研究：驱动龙卷风涡产生和维持的动力学过程

• 批准号: 1137153
• 负责人: Marcus Buker
• 金额: $ 17.92万
• 依托单位: Western Illinois University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-10-01 至 2017-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1137153&HistoricalAwards=false
• 关键词: Collaborative; Research; Dynamical; Processes; Driving

This research will focus on an investigation of the dynamics resulting in the genesis and maintenance of tornadic vortices. The overarching hypothesis of the study is following: Smaller (subtornado vortex-scale) vortical structures in the vicinity of a primary tornado vortex undergo gyroscopically driven alignment, followed by a generalized merging process. This leads to a natural steepening of the vorticity gradient on the outer edge of the tornadic circulation. Ultimately, this isolates the vortex from turbulence-induced erosion processes. The isolation process then enables the tornado vortex to achieve strengths not easily simulated with traditional numerical models, even with resolution deemed sufficient to resolve that vortex. Intellectual Merit: The processes leading to vortex isolation are not well represented in quasi-two-dimensional traditional atmospheric dynamics theory. Instead, the study adopts a new theoretical framework based on an analogy of the Navier-Stokes equation (hydrodynamics-HD) with electromagnetic (EM) theory. This framework has been growing in acceptance in the computational fluid dynamics (CFD) community, particularly over the last 15 years. One key point in this new approach exploits the analogous behavior between the alignment of magnetic domains within an external magnetic field, and vortical turbulence being driven to alignment (and merging) with the tornado vortex.The research is on two fronts: (1) numerical modeling of the isolation process and (2) theoretical development describing three-dimensional scale interaction processes producing that isolation. A formulation of a vorticity backscatter process based on resolvable vorticity structure will be resulted. This new framework will then be built into the numerical model used to enable the simulation of a tornado without extreme resolution. Broader Impacts The adopted methodologies embracing an EM-HD analogy will likely enhance understanding of all atmospheric vortex dynamics, including those that govern tropical cyclones. While this will result in a more robust comprehension of these complex processes, it will also introduce a simple, intuitive, overarching framework for future investigations. The two principal investigators plan to take advantage of this simplification to create new teaching tools that articulate the complexities of tornado formation and maintenance in a clear manner to the general public. Additionally, this work will serve as a catalyst for stressing the importance of a well-rounded physics background (including the fundamentals of electromagnetism), especially for those entering the fields of atmospheric science and fluid dynamics.

这项研究将集中在动力学的调查，导致龙卷风涡的产生和维持。研究的总体假设如下：较小的（亚龙卷风涡尺度）涡结构在附近的一个主要龙卷风涡进行陀螺仪驱动的对齐，其次是一个广义的合并过程。这导致龙卷风环流外缘的涡度梯度自然变陡。 最终，这将涡流与湍流引起的侵蚀过程隔离开来。然后，隔离过程使龙卷风涡流能够达到传统数值模型难以模拟的强度，即使分辨率被认为足以解决该涡流。智力优势：传统的准二维大气动力学理论不能很好地描述导致涡旋孤立的过程。 相反，这项研究采用了一个新的理论框架的基础上类比的Navier-Stokes方程（流体力学-HD）与电磁（EM）理论。 这个框架在计算流体动力学（CFD）社区的接受度越来越高，特别是在过去的15年里。 这种新方法的一个关键点是利用了外部磁场中磁畴排列和涡旋湍流被驱动与龙卷风涡旋排列（并合并）之间的类似行为，研究分为两个方面：（1）隔离过程的数值模拟和（2）描述产生隔离的三维尺度相互作用过程的理论发展。 基于可分辨的涡度结构，将得到涡度后向散射过程的公式。 这个新的框架将被纳入用于模拟龙卷风的数值模型中，而无需极端的分辨率。 所采用的方法包括EM-HD类比，可能会提高对所有大气涡旋动力学的理解，包括那些支配热带气旋的动力学。虽然这将导致对这些复杂过程的更强有力的理解，但它也将为未来的调查引入一个简单，直观的总体框架。 两位主要研究人员计划利用这种简化来创建新的教学工具，以清晰的方式向公众阐述龙卷风形成和维持的复杂性。 此外，这项工作将作为一种催化剂，强调全面的物理背景（包括电磁学的基本原理）的重要性，特别是对于那些进入大气科学和流体动力学领域。