2026 Birnbaum Bubble Multiscale Magma Modeling

Bubble growth in silicate melts drives significant volume expansion, influencing magma transport dynamics. This study aims to investigate how magma flow is affected by bubble expansion through the development of a coupled micro-mechanical and macro-scale model. We combined a model that tracks volatile diffusion into individual bubbles with one that focuses on thermal evolution and fluid flow within the surrounding magmatic suspension. Our approach identifies distinct dynamical regimes governed by various limiting factors including viscous resistance, diffusion at the bubble scale, and outgassing through permeable interfaces. We observe that the interaction between internal bubble dynamics and external boundary conditions leads to complex feedback mechanisms between growth and resorption, which emerge naturally from local conditions. The findings highlight the importance of high-viscosity boundary layers affected by temperature and volatile concentration gradients in modulating flow and bubble evolution. To facilitate the application of our model to diverse systems, we employed a flexible numerical framework termed MVFFIN. This work provides a unified understanding of multiscale degassing processes and their implications for magmatic transport and fragmentation, which are critical for predicting volcanic eruptions.