Coupled fluid and solid evolution in analogue volcanic vents

摘要: Volcanic eruptions emit rock particulates and gases at high speed pressure, which change the shape of surrounding rock. Simplified analytical solutions, field studies, numerical models suggest that this process plays an important role in behavior hazards associated with explosive volcanic eruptions. Here we present results from a newly developed laboratory-scale apparatus designed to study coupled process. The experiments used compressed air jets expanding into laboratory through fabricated analogue material, evolves time during experiment. was injected approximately 2.5 times atmospheric pressure. We analogues sand steel powder samples three-dimensional printing studied fluid development using phase-locked particle image velocimetry, while simultaneously observing solid via video camera. found response much more rapid than solid, permitting quasi-steady approximation. In most cases, vent flared out rapidly, increasing its diameter by 20 100%. After initial expansion, flow achieved near-steady condition for long duration. new expanded shapes permitted lower exit pressures larger jet radii. one experiment, after establishment steady behavior, failure occurred second time, resulting state. This not precipitated changes nozzle condition, it radically changed downstream dynamics. experiment suggests brittle nature host enables sudden expansion middle eruption without requiring conduit flow.