HR: 17:30h
AN: V34B-07    [Abstracts]
TI: Preliminary Benchmarking of Numerical Simulations of the Supersonic Behavior of Plinian Eruptions
AU: * Ogden, D E
EM: dogden@es.ucsc.edu
AF: University of California at Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 United States
AU: Wohletz, K H
EM: wohletz@lanl.gov
AF: Los Alamos National Laboratory, Geophysics Group, EES-11, MS F665, Los Alamos, NM 87545 United States
AU: Glatzmaier, G A
EM: glatz@es.ucsc.edu
AF: University of California at Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 United States
AU: Peterson, A H
EM: audreyp@lanl.gov
AF: Los Alamos National Laboratory, Geophysics Group, EES-11, MS F665, Los Alamos, NM 87545 United States
AB: Advances in computational methods allow more accurate simulations of explosive volcanic phenomena, involving both fluid and solid mechanics. CFDLib, developed by the Theoretical Division at Los Alamos National Laboratory, provides the unique capability of being able to solve the interaction of an Eulerian fluid with a Lagrangian solid in 3D while treating multiphase turbulence that this interaction generates. This capability provides a means for studying an essential element of Plinian eruption: the effect of an evolving conduit and vent on the erupting multiphase flow and the flow's effect upon the conduit and vent rocks, a 3D geological nozzle problem. Because the coupling of the host rock solid mechanics with the fluid dynamics of an erupting multiphase fluid has never been directly simulated, our first challenge is to validate CFDLib for this geophysical application. Validation is generally accomplished by simulating well-studied laboratory experiments and analytical solutions, such as the Sod shock tube and Sedov-Taylor blast wave, which ensures that the Arbitrary-Eulerian-Lagrangian solution technique in CFDLib is reliable. Validation can also be accomplished by benchmarking results with those provided by other computational results. Such validation is rarely demonstrated for computational methods applied to volcanic eruptions, but with a growing reliance on numerical results for hazard prediction, the need for validation becomes paramount. We demonstrate some of our initial benchmarking results, including those of a convecting fluid and a supersonic jet. The convection simulation is of water in a two-dimensional box that is driven by a heated bottom boundary and cooled top boundary. The simulation has a traditional Rayleigh number of 10¹⁰ and resolves turbulent eddies at small scales. The supersonic jet benchmark simulates a laboratory jet of overpressured air expanding through a small nozzle (5mm radius) into a box. Pressure ratios between the box and the expanding jet ranging from 2:1 to 8:1 are examined. The positions of the first Mach disk in the simulated and experimental jets are compared.
DE: 0550 Model verification and validation
DE: 0560 Numerical solutions (4255)
DE: 8414 Eruption mechanisms and flow emplacement
DE: 8428 Explosive volcanism
SC: Volcanology, Geochemistry, Petrology [V]
MN: Fall Meeting 2005