 |
| Titel |
Dissection of crystal bearing melts rheology |
| VerfasserIn |
Benoit Cordonnier, Michael Manga, Boris Kauss |
| Konferenz |
EGU General Assembly 2011
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250049268
|
|
|
|
|
|
| Zusammenfassung |
| The major drawback to scale back experimental results to volcanic systems is a
good comprehension of the physical processes involved. The rheology of magmatic
suspensions is a complex flow of bubbles, crystals and melt. The crystal is the phase,
which after temperature, affects the most the viscosity of magmas (> 7 orders of
magnitude). The dynamics of crystal bearing melts is a complex combination of a liquid
flowing around a solid network of particles, themselves displaced and aligned by
the fluid but constrained by their own network. Many parameters affects a fluid
suspension, the most effective being the crystal fraction, the bulk stress and the
temperature.
Our results constrain experimentally, theoretically and numerically the different flow
regimes of crystal bearing melts namely Newtonian, hydrodynamic, friction, lubrication,
turbulent and brittle regimes.
Two major effects explain the increase of apparent viscosity of magmatic suspensions: the
stress localisation within the melt phase and the effects due to the crystal network. As stated
above the stress within the fluid phase will align the crystals but the crystal arrangement will
define the stress within the fluid. For a given stress, the suspension will find an equilibrium
between these two competitive effects. It comes that for quantification reasons, one this two
parameter has to be fixed in order to evaluate the other. Here we present two-phase
flow numerical simulations performed to constrain the effect of stress localisation
within the fluid. Our numerical results obtained on the melt phase demonstrates how
the stress localizes for different crystals pattern (i.e. random, clusters or aligned). |
|
|
|
|
|
|