从膨胀到坍塌：开放体系岩浆中的气泡与连续体多尺度建模
From expansion to collapse: Bubble and continuum multiscale modeling in open-system magmas
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中文总结 AI 辅助
该研究耦合气泡微观力学模型与岩浆宏观热流模型，识别岩浆气泡演化的不同动力学 regime，开发 MVFFIN 框架，为理解多尺度脱气对岩浆运移与碎裂的影响提供统一方法。
中文摘要 AI 辅助
硅酸盐熔体中的气泡生长会引发显著的体积膨胀，这对岩浆运移动力学具有一级控制作用。当岩浆暴露于外部环境时，自由表面的热量与挥发分损失会使气泡生长逆转，导致收缩，并在扩散、流变性与流动之间形成复杂的反馈。为解决岩浆流动如何控制气泡膨胀或被其控制的问题，我们将针对单个气泡内挥发分扩散的微观力学模型，与周围岩浆悬浮体的宏观尺度热演化及流体流动相耦合。这种双向耦合可捕捉气泡尺寸、熔体黏度与压力梯度的协同演化，使生长与再吸收过程均能由局部条件自然产生。我们确定了由以下因素主导的不同动力学 regime：（i）气泡生长受（a）黏性阻力或（b）气泡尺度扩散限制；（ii）悬浮体的黏性输运；（iii）通过可渗透多孔网络及暴露的岩浆-流体界面的脱气；（iv）热淬火。在所有 regime 中，由温度与挥发分浓度梯度形成的薄而高黏度边界层，在调控流动与气泡演化中发挥核心作用。该模型在灵活的模块化数值框架（Multiscale Vesiculation, Fluid flow, Failure, and Interaction Nonlinear model: MVFFIN）中实现，可扩展至多种系统与应用，包括管道流动与火山碎屑演化。通过解析内部气泡动力学与外部边界条件的相互作用，该方法为理解多尺度脱气及其对岩浆运移与碎裂的影响提供了统一框架。
英文摘要
Bubble growth in silicate melts drives significant volume expansion, which has a first order control on magma transport dynamics. When magmas are exposed to external environments, heat and volatile loss at free surfaces can reverse bubble growth, leading to shrinkage and complex feedbacks between diffusion, rheology, and flow. To resolve how magma flow controls, or is controlled by, bubble expansion, we couple a micro-mechanical model for volatile diffusion into individual bubbles, with a macro-scale thermal evolution and fluid flow of the surrounding magmatic suspension. This two-way coupling captures the co-evolution of bubble size, melt viscosity, and pressure gradients, allowing both growth and resorption to emerge naturally from local conditions. We identify distinct dynamical regimes governed by (i) bubble growth limited by (a) viscous resistance or (b) diffusion at the bubble scale, (ii) viscous transport of the suspension, (iii) outgassing through permeable porous networks and exposed magma-fluid interfaces, and (iv) thermal quenching. Across these regimes, thin, high-viscosity boundary layers arising from temperature and volatile concentration gradients play a central role in modulating flow and bubble evolution. The model is implemented in a flexible, modular numerical framework (Multiscale Vesiculation, Fluid flow, Failure, and Interaction Nonlinear model: MVFFIN) enabling extension to a wide range of systems and applications, including conduit flow and pyroclast evolution. By resolving the interplay between internal bubble dynamics and external boundary conditions, this approach provides a unified framework for understanding multiscale degassing and its impact on magmatic transport and fragmentation.
