EXPERIMENTAL SIMULATIONS OF GAS-DRIVEN ERUPTIONS: KINETICS OF BUBBLE GROWTH AND EFFECT OF GEOMETRY

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dc.contributor.author Zhang Y.
dc.date.accessioned 2020-12-30T02:36:38Z
dc.date.available 2020-12-30T02:36:38Z
dc.date.issued 1998
dc.identifier https://elibrary.ru/item.asp?id=1044949
dc.identifier.citation Bulletin of Volcanology, 1998, , 4, 281-290
dc.identifier.issn 0258-8900
dc.identifier.uri https://repository.geologyscience.ru/handle/123456789/21702
dc.description.abstract Simulated gas-driven eruptions using CO2-water-polymer systems are reported. Eruptions are initiated by rapidly decompressing CO2-saturated water containing up to 1.0 wt.% CO2. Both cylindrical test cells and a flask test cell were used to examine the effect of magma chamber/conduit geometry on eruption dynamics. Bubble-growth kinetics are examined quantitatively in experiments using cylindrical test cells. Uninhibited bubble growth can be roughly expressed as dr/dt≈λD(β-1)/(γt1/3) for a CO2-water-polymer system at 0-22 °C and with viscosities up to 5 Pa·s, where r is the radius of bubbles, λ and D are the Ostwald solubility coefficient and diffusivity of the gas in the liquid, β is the degree of saturation (decompression ratio), and γ characterizes how the boundary layer thickness increases with time and is roughly 1.0×10-5 m/s1/3 in this system. Unlike the radius of cylindrical test cells, which does not affect the eruption threshold and dynamics, the shape of the test cells (flask vs cylindrical) affects the dynamics but not the threshold of eruptions. For cylindrical test cells, the front motion is characterized by constant acceleration with both Δh (the height increase) and ΔV (the volume increase) being proportional to t2; for the flask test cell, however, neither Δh nor ΔV is proportional to t2 as the conduit radius varies. Test-cell geometry also affects foam stability. In the flask test cell, as it moves from the wider base chamber into the narrower conduit, the bubbly flow becomes fragmented, affecting the eruption dynamics. The fragmentation may be caused by a sudden increase in acceleration induced by conduit-shape change, or by the presence of obstacles to the bubbly flow. This result may help explain the range in vesicularities of pumice and reticulite.
dc.subject GAS-DRIVEN ERUPTIONS
dc.subject EXPLOSIVE VOLCANISM
dc.subject LIMNIC ERUPTIONS
dc.subject PUMICE
dc.subject EXPERIMENTAL VOLCANOLOGY
dc.subject BUBBLE GROWTH
dc.subject VESICULARITY
dc.title EXPERIMENTAL SIMULATIONS OF GAS-DRIVEN ERUPTIONS: KINETICS OF BUBBLE GROWTH AND EFFECT OF GEOMETRY
dc.type Статья


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