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| Titel |
Non-Newtonian flow of bubbly magma in volcanic conduits |
| VerfasserIn |
Simone Colucci, Paolo Papale, Chiara Paola Montagna |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250145434
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| Publikation (Nr.) |
 EGU/EGU2017-9373.pdf |
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| Zusammenfassung |
| The dynamics of magma ascent along volcanic conduits towards the Earth’s surface affects
eruptive styles and contributes to volcanic hazard. The rheology of ascending magmatic
mixtures is known to play a major role on mass flow rate as well as on pressure and exit
velocity at the vent, even determining effusive vs explosive eruptive behaviour. In this work
we explore the effects of bubble-induced non-Newtonian rheology on the dynamics of
magma flow in volcanic conduits. We develop a quasi-2D model of magma ascent that
incorporates a rheological constitutive equation describing the strain-dependent
effect of gas bubbles on the viscosity of the multiphase magma. Non-Newtonian
magma flow is investigated through a parametric study where the viscosity of the
melt and the water content are varied over natural ranges. Our results show that
non-Newtonian rheology leads to greater exit velocity, mass flow, and density. The
pressure distribution along the conduit remains very similar to the Newtonian case,
deviating only at the conduit exit. Plug-like velocity profiles develop approaching
the conduit exit, when mixture velocity is high, and are favored by smaller liquid
viscosity. Since the mass flow rate, the density and the velocity of the mixture exiting
from the conduit are fundamental for quantifying and assessing the transport and
emplacement dynamics, neglecting the non-Newtonian effect of bubble-bearing magmas
may result in misinterpretation of the deposit and, consequently, eruptive behavior. |
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