Collaborative Research: Laboratory and theoretical study of geyser dynamics

每年有超过400万游客来到黄石的老忠实间歇泉，公众对间歇泉的迷恋是不可否认的。然而，对间歇泉的科学认识还不完整。一个多世纪以来，人们都知道间歇泉的喷发是由地下管道中的水突然沸腾引起的，但科学家们不知道是什么引发了这些沸腾事件，也不知道地下管道的大小和形状如何影响间歇泉的行为。最近对黄石国家公园的间歇泉田、智利高原的埃尔塔修和堪察加半岛的间歇泉谷的研究表明，这些地点的地下管道系统包括一个与主喷发管道相对的水库。在这种系统中，蒸汽在侧储层中被捕获，因此被称为“气泡疏水阀”。这种几何结构的发现是几十年来最重大的进步，但研究人员才刚刚开始了解它是如何影响间歇泉的行为的。这个小组将在实验室里建立一个小型间歇泉装置，其中包括一个气泡陷阱。他们将进行一系列实验来研究流体在这类系统中的行为。这项提议的工作将使用数学模型将实验室中观察到的行为与我们在自然界中遇到的更大的系统联系起来。该项目将为本科生提供研究经验，并通过已建立的教师培训计划为教育工作者提供教学材料。实验室间歇泉将在Lamont Doherty地球天文台的开放日展出，每年有成千上万的人参观。间歇泉代表了一类独特的热液系统，其中两相（蒸汽和液体）流动的热力学和有利的管道几何形状相结合，产生了间歇性喷发。每年有超过400万游客来到黄石的老忠实间歇泉，公众对间歇泉的迷恋是不可否认的，但我们对间歇泉的科学理解是不完整的。然而，最近来自黄石国家公园的间歇泉田、智利高原上的El Tatio和堪察加半岛的间歇泉谷的数据，为管道几何形状提供了令人信服的证据，其中包括一个与喷发管道横向偏移的水库。这种所谓的“气泡陷阱”几何结构允许压缩蒸汽在不透水的屋顶下积聚，它的发现使间歇泉研究重新焕发活力，因为该团队试图了解它对间歇泉动态行为的影响。迄今为止，没有一个实验室间歇泉实验能准确地模拟在自然系统中观察到的全部行为，气泡陷阱管道几何形状的影响也没有得到彻底的探索。同样，一个多世纪以来，数学模型一直是间歇泉研究的基础，但现有的模型都没有考虑到与气泡陷阱管道几何形状相关的热力学和流体力学过程的全部范围。这个项目将通过结合新颖的实验室实验来解决这两个缺点，这些实验包括间歇泉缺失的部分和气泡陷阱。实验室模拟间歇泉将提供天然间歇泉的热力学过程和地下几何形状的理想化表示，使一系列旨在阐明间歇泉系统流体力学和热力学行为的实验成为可能。同时，将开发数学模型来描述系统行为，这些关系将用于提高我们对自然系统的理解。实验室间歇泉将能够评估喷发触发的相互竞争的假设，综合监测仪器将能够以前所未有的细节观察间歇泉的过程。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With over 4 million annual visitors to Yellowstone's Old Faithful geyser, public fascination with geysers is undeniable. Yet, the scientific understanding of geysers is incomplete. While it has been understood for over a century that geyser eruptions are caused by the sudden boiling of water in underground conduits, scientists do not understand what triggers these boiling events, and how the size and shape of the underground conduits affect a geyser’s behavior. Recent studies at geyser fields in Yellowstone National Park, El Tatio on the Chilean altiplano, and the Geyser Valley in Kamchatka, have shown that the underground plumbing systems at these sites include a reservoir that is offset to the side relative to the main eruption conduit. In such systems, steam gets captured in the side reservoir, earning it the name ‘bubble trap’. The discovery of this geometry is the most significant advance in several decades, but researchers are only beginning to understand how it affects a geyser's behavior. This team will create a small geyser setup in the laboratory that will include a bubble trap. They will run a series of experiments to study how fluids behave in this type of system. The proposed work will use mathematical models to relate behaviors observed in the lab to the much larger systems that we encounter in nature. The project will provide research experiences for undergraduate students and will contribute instructional materials to educators through an established teacher training program. The laboratory geyser will be exhibited at the Lamont Doherty Earth Observatory open house, visited by thousands of people each year.Geysers represent a unique class of hydrothermal systems where the thermodynamics of two-phase (vapor and liquid) flow and favorable conduit geometries combine to produce episodic eruptions. With over 4 million annual visitors to Yellowstone's Old Faithful geyser, public fascination with geysers is undeniable, but our scientific understanding of geysers is incomplete. Recently, however, data from geyser fields in Yellowstone National Park, El Tatio on the Chilean altiplano, and the Geyser Valley in Kamchatka, have provided compelling evidence for conduit geometries that include a reservoir that is laterally offset from the eruption conduit. This so-called 'bubble trap' geometry allows compressed steam to accumulate under an impermeable roof, and its discovery has revitalized geyser research as this team seeks to understand its implications for a geyser's dynamic behavior. None of the laboratory geyser experiments developed to-date accurately simulates the full range of behaviors observed in natural systems, and the effects of bubble trap conduit geometries have not been explored thoroughly. Similarly, mathematical models have informed geyser research for more than a century, but none of the extant models considered the full range of thermodynamic and fluid mechanics processes associated with a bubble trap conduit geometry. This project will address both of these shortcomings by combining novel laboratory experiments that include the missing pieces for geysers with a bubble trap. The laboratory analog geyser will provide an idealized representation of the thermodynamic processes and subsurface geometries of natural geysers, enabling a series of experiments aimed at elucidating the fluid mechanical and thermodynamic behaviors of the geyser system. In parallel, mathematical models will be developed to describe the system behavior, and these relationships will be used to improve our understanding of natural systems. The laboratory geyser will enable the evaluation of competing hypotheses for eruption triggering, and comprehensive monitoring instrumentation will enable the observation of geyser processes in unprecedented detail.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.