HR: 0800h
AN: V21A-0377 [Abstracts]
TI: Lattice Boltzmann model of lava lake convection and solidification
AU: * Huber, C
EM: chuber@seismo.berkeley.edu
AF: University of California - Berkeley, Department of Earth and Planetary Science, 307 McCone
Hall #4767, Berkeley, CA 94720-4767, United States
AU: Manga, M
EM: manga@seismo.berkeley.edu
AF: University of California - Berkeley, Department of Earth and Planetary Science, 307 McCone
Hall #4767, Berkeley, CA 94720-4767, United States
AU: Parmigiani, A
EM: Andrea.Parmigiani@terre.unige.ch
AF: Universite de Geneve, Section des Sciences de la Terre, 13 rue des maraichers, Geneva,
GE 1205, Switzerland
AB:
Lava lakes can be viewed as large-scale chemical and thermo-hydrodynamical laboratories, providing unique
opportunities to study the coupling between fluid dynamics and liquid-solid phase changes in magmas.
Previous studies of the thermal history of lava lakes were mostly based either on heat conduction models, apply a
1D treatment of convective cooling, or use experimental analogs. Here we describe a new numerical tool to solve
for the evolution of fluids that can convect and undergo a phase change (solidification in this case). The
numerical model is based on the lattice Boltzmann method and includes features such as floor and roof cooling,
temperature- and crystallinity-dependent viscosity. Crystallization occurs at the two cooling interfaces (roof and
floor), as well as within the subcooled convecting fluid. Convection is driven by the negative buoyancy of high solid
fraction magma, leading to driping instabilities originating from the thermal boundary layer under the roof of the
lake.
Our model permits us to study the effects of convection on the solidification time of lava lakes. We also investigate
the evolution of the geometry of the solidification fronts. Finally, we test the importance of the choice of upper
thermal boundary condition, namely isothermal versus radiative.
The lattice Boltzmann approach presented here can be further modified to study chemical differentiation
processes and crystal settling in a magmatic environment subjected to cooling.
DE: 0515 Cellular automata
DE: 0545 Modeling (4255)
DE: 8425 Effusive volcanism
DE: 8429 Lava rheology and morphology
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting