The Interaction of Pyroclastic Density Currents with the Atmosphere & Landscapes: Integrating Experiments and Computational Approaches for Validation & Examination of Entra

火山碎屑密度流与大气的相互作用

• 批准号: 1841376
• 负责人: Josef Dufek
• 金额: $ 17.19万
• 依托单位: University of Oregon Eugene
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-05-16 至 2020-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1841376&HistoricalAwards=false
• 关键词: Interaction; Pyroclastic; Density; Currents; Atmosphere

Pyroclastic density currents (PDCs) are among the most dangerous and unpredictable volcanic phenomena. These currents threaten over 200 million people worldwide. The currents are generated when mixtures of explosively erupted material are greater density than the atmosphere and are characterized by high velocities and temperatures making them particularly dangerous for people and infrastructure. Yet direct observation of the internal workings of these currents have been confounded by the difficulty in predicting their occurrence, hazardous conditions, and opacity limiting observation of the internal dynamics. These currents often have heterogeneous particle concentrations in a single current, so that a solitary event will have a range of spatial-temporally evolving and overlapping physical processes. Ultimately these currents are driven by the density contrast between the current and the atmosphere, and any process (such as air entrainment or erosion of the substrate) that changes the particle concentration of the current will significantly impact their dynamics. In this way, PDC are sensitive to and communicate with the atmosphere and landscape through which they travel. However, there is a distinct gap in knowledge concerning entrainment and erosion in PDC. The proposed work will conduct large-scale experiments and numerical simulations to determine internal physical processes in PDC. This information will be used to improve our numerical simulation tools to better understand the hazards from these flows.This proposed work will integrate the results of several styles of experiments that emphasize end member processes and scales important for PDC dynamics. Select experimental results will be used to validate the numerical simulation of these processes, while other experiments will explore two important physical processes in PDC, entrainment and erosion. We will address the following inter-related goals: 1. Validate fluid dynamics models to encompass the particle concentration and fluid dynamics environment experienced throughout an evolving PDC, 2. Determine the entrainment efficiency of PDC and relate this to thermal evolution and transport capacity, 3. Assess the ability of entrainment to generate self-fluidization, 4. Assess bed forces from both particle and gas sources and relate these to the erosive capacity, 5. Generate modules for entrainment and erosion that can be incorporated into any numerical approach with a particular emphasis on rapid, end-member models to aid in hazard assessment, and 6. Develop a "Fluid Dynamics of PDC" video/lesson plan that highlights the visualizations from both experiments and simulations to educate students on the range of fluid dynamics in PDC.

火山碎屑密度电流（PDC）是最危险和不可预测的火山现象之一。这些电流威胁着全球超过2亿人。当爆炸材料的混合物比大气更高，并且具有高速度和温度，使其对人们和基础设施特别危险时，就会产生电流。然而，由于难以预测其发生，危险条件和不透明度限制内部动力学观察的困难，对这些电流的内部工作的直接观察一直困惑。这些电流在单个电流中通常具有异质粒子浓度，因此孤立事件将具有一系列空间端的变化和重叠的物理过程。最终，这些电流是由电流和大气之间的密度对比驱动的，以及任何改变电流颗粒浓度的过程（例如空气夹带或底物的侵蚀）都会显着影响其动力学。通过这种方式，PDC对它们所经过的气氛和景观敏感并沟通。但是，关于PDC中的夹带和侵蚀的知识存在明显的差距。提出的工作将进行大规模实验和数值模拟，以确定PDC中的内部物理过程。这些信息将用于改善我们的数值模拟工具，以更好地了解这些流量的危害。这项建议的工作将整合几种实验样式的结果，这些实验强调最终成员过程和对PDC动力学重要的量表。选择的实验结果将用于验证这些过程的数值模拟，而其他实验将探索PDC，夹带和侵蚀中的两个重要的物理过程。我们将解决以下相关目标：1。验证流体动力学模型，以涵盖颗粒的浓度和流体动力学环境，整个不断发展的PDC，2。确定PDC的夹带效率，并将其与热进化和运输能力相关联，3。评估侵点能力，以评估构成粒子的能力，4.。可以将夹带和侵蚀的模块纳入任何数值方法中，特别着重于快速，结束的模型，以帮助进行危险评估，6。开发“ PDC的流体动力学”视频/课程计划，强调了来自实验和模拟的可视化范围，以对PDC中的流体动力学范围进行教育。

项目成果

Generation of air lubrication within pyroclastic density currents

• DOI: 10.1038/s41561-019-0338-2
• 发表时间: 2019-05-01
• 期刊: NATURE GEOSCIENCE
• 影响因子: 18.3
• 作者: Lube, Gert;Breard, Eric C. P.;Wang, Ting
• 通讯作者: Wang, Ting

Multiphase flow behaviour and hazard prediction of pyroclastic density currents

火山碎屑密度流的多相流行为及危险预测

• DOI: 10.1038/s43017-020-0064-8
• 发表时间: 2020
• 期刊: Nature Reviews Earth & Environment
• 影响因子: 42.1
• 作者: Lube, Gert;Breard, Eric C.;Esposti-Ongaro, Tomaso;Dufek, Josef;Brand, Brittany
• 通讯作者: Brand, Brittany

The dynamics of granular flow from a silo with two symmetric openings

• DOI: 10.1098/rspa.2018.0462
• 发表时间: 2019-01
• 期刊: Proceedings of the Royal Society A
• 作者: L. Fullard;E. Breard;C. Davies;A. Godfrey;M. Fukuoka;A. Wade;J. Dufek;G. Lube