HR: 16:30h
AN: V14A-03    [Abstracts]
TI: Model studies for the length of a lava tube
AU: * Whitehead, J A
EM: jwhitehead@whoi.edu
AF: Woods Hole Oceanographic Institution, MS21, Woods Hole, MA 02543,
AU: Holmes, M
AF: Courant Institute, NYU, Mercer street, New York, NY 10013,
AB: Laboratory experiments with flowing wax over a cooled disc show that the wax forms channels of melt. For certain conditions, the channels allow steady flow indefinitely, and for others the channels freeze, forcing the wax to flow elsewhere or stop. This has motivated the study of the fluid mechanics and thermal balances of a viscous melted substance flowing in a cold circular tube. As the melt flows it cools and solidifies at the tube radius and we investigate the question "how far can the melt flow and remain liquid?" A theoretical solution is derived for the tube radius (which varies in space and time) and the temperature profiles in liquid and solid. If the melt source is maintained at a constant flux the distance can be infinite, but if the melt source is maintained at constant pressure difference across the length of the tube, then there is a maximum length which depends on the Peclet number and a dimensionless temperature. Conditions are derived for which the radius is unstable. This produces a bound on the distance the melt can travel. These predictions are further investigated with numerical and laboratory experiments. The formula for distance is use to predict the longest possible distance for lava tubes in volcanic systems.
DE: 8414 Eruption mechanisms and flow emplacement
DE: 8434 Magma migration and fragmentation
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting