CAREER:The Role of Proximal Dynamics and Particle Aggregation in Ash Dispersal: An Educational, Numerical, Field and Laboratory Approach

火山爆发会向大气中注入大量的火山灰，可能会破坏全球的基础设施，最近冰岛的Eyjafjallajökull火山爆发就是一个例证。虽然在发展火山灰扩散模型和对远离火山口的火山灰迁移过程的概念理解方面取得了重大进展，但目前对火山灰扩散的预测中有很大的不确定性是由于对管道和火山口附近的颗粒动力学描述有限。拟议的工作将通过计算、现场和实验室的方法，检查由于管道中的喷发过程和羽流中的多相相互作用而改变粒子在能量谱上的粒度分布的物理过程。火山灰扩散模型关注的是远程扩散，并结合了大气模型的条件。由于在这些领域的投资和进步，这项工作的目标之一是提供改进的源项和物理理解，可以很容易地采用到任何分散模型中。为了开发一个综合框架，我们将解决以下问题、目标和相关假设：破碎后的管道过程如何在设置进入大气的出口条件中发挥作用？2. 喷口条件和夹带物理如何影响羽流的粒度分选？3. 含水聚集在火山灰近端分布中起什么作用？所有这些问题将紧密相连，并将使用精心挑选的现场例子，实验室实验，数值模拟和可视化工具。这项工作还将开发一套完整的流体动力学模块、远程教学工具和基于网络的工具，使高中生能够更多地了解火山学和地球科学。这一方法的设计目的是要接触到广泛的高中受众，在第一阶段将会接触到少数民族人口较多的几所学校。此外，这些工具将通过web应用程序和可用于博物馆展示的交互式三维可视化工具向更广泛的公众推广。

Explosive volcanic eruptions can inject voluminous amounts of ash into the atmosphere potentially crippling global infrastructure as witnessed by the recent eruption of Eyjafjallajökull in Iceland. While significant improvements have been made in the development of ash dispersal models and in the conceptual understanding of processes that govern the transport of ash far from the volcanic vent, much of the uncertainty in current forecasts of ash dispersal occurs due to limited description of particle dynamics in the conduit and near the vent. The proposed work will examine the physical processes that modify the grain size distribution of particles across a spectrum of energies due to eruptive processes in the conduit and multiphase interaction in the plume using computational, field and laboratory approaches.Ash dispersal models have focused on long-range dispersal, incorporating conditions from atmospheric models. Due to the investment and advances in these fields, one of the goals of this work is to provide improved source terms and physical understanding that can be readily adopted into any dispersal model. To develop an integrated framework, we will address the following questions, objectives and related hypotheses: 1. How do post-fragmentation conduit processes play a role in setting the exit conditions into the atmosphere? 2. How do vent conditions and entrainment physics contribute to grain size sorting in plumes? 3. What role does hydrous aggregation play in the proximal distribution of ash? All of these questions will be closely linked and will make use of carefully chosen field examples, laboratory experiments, numerical simulations and visualization tools. This work will also develop an integrated set of fluid dynamics modules, teaching at a distance tools, and web based tools to enable high school students to learn more about volcanology and earth sciences in general. This approach has been designed to reach a broad high school audience, and in its first phase will reach several schools with large minority populations. Additionally these tools will be promoted to the broader public through web applications and through interactive three-dimensional visualizations tools that can be used in museum displays.