Collaborative Research: Heterogeneous Bubble Dynamics in Volcanic Conduits

火山喷发可能对生活、基础设施、商业和气候产生重大影响。喷发的岩浆是炽热的岩石碎片(以前是岩浆)的混合物，如火山灰和火山气体，它们在喷发的岩浆中以气泡的形式输送到地表。气泡既可能限制岩浆气体，可能导致巨大的过剩气体压力，也可能通过在气泡合并过程中形成渗透性网络，促进气体的协同损失。因此，气泡在岩浆上升速率的反馈中起着至关重要的作用，并影响火山喷发的方式和爆炸强度。这一项目将进一步加深我们对火山喷发过程中影响气泡和岩浆气体的各种过程的定量理解。我们将开发一个新的气泡尺度的数值模型，用于气泡的生长、变形和合并。该模型将被校准到实验室实验，这些实验是专门为促进经验数据的整合而设计的。然后，气泡尺度模型将与多相管道流动模型相结合，以解决以下问题：(1)具有多分散气泡尺寸分布的喷发岩浆中气体压力的时空演变；(2)岩浆破碎的含义；(3)喷发岩浆剪切变形期间的气泡合并；(4)通过合并气泡的渗透性流动造成的开放系统气体损失；以及(5)上升岩浆中的剪切局部化。

Volcanic eruptions can have significant impact on life, infrastructure, commerce and climate. Erupting magma is a mixture of hot rock fragments (formerly magma), such as volcanic ash, and volcanic gases that are transported to surface as bubbles within the erupting magma. Bubbles may both, confine magmatic gases potentially resulting in large excess gas pressures, or they may facilitate syneruptive gas loss by forming permeable networks during bubble coalescence. Consequently, bubbles play a crucial role in a feedback with magma ascent rate and affect the style and explosive intensity of eruptions.This project will further our quantitative understanding of the various processes that affect bubbles and magmatic gases during volcanic eruptions. We will develop a new bubble-scale numerical model for bubble growth, deformation and coalescence. The model will be calibrated to laboratory experiments that are specifically designed to facilitate the integration of empirical data. The bubble-scale model will then be coupled with a multiphase conduit flow model to address problems such as (1) the spatiotemporal evolution of gas pressure in an erupting magma with a polydisperse bubble size distribution; (2) the implications for magma fragmentation; (3) bubble coalescence during shear deformation of the erupting magma; (4) open-system gas loss by permeable flow through coalesced bubbles; and (5) shear localization within the ascending magma.