Anisotropic convection model for the earth's mantle

Muhlhaus, H. B., Cada, M. and Moresi, L. (2003) Anisotropic convection model for the earth's mantle. Computational Science - Iccs 2003, Pt Iii, Proceedings, 2659 : 788-797.

Author Muhlhaus, H. B.
Cada, M.
Moresi, L.
Title Anisotropic convection model for the earth's mantle
Journal name Computational Science - Iccs 2003, Pt Iii, Proceedings   Check publisher's open access policy
ISSN 0302-9743
ISBN 3-540-40196-2
Publication date 2003
Sub-type Article (original research)
Volume 2659
Start page 788
End page 797
Total pages 10
Place of publication Berlin
Publisher Springer-verlag Berlin
Language eng
Abstract The paper presents a theory for modeling flow in anisotropic, viscous rock. This theory has originally been developed for the simulation of large deformation processes including the folding and kinking of multi-layered visco-elastic rock (Muhlhaus et al. [1,2]). The orientation of slip planes in the context of crystallographic slip is determined by the normal vector - the director - of these surfaces. The model is applied to simulate anisotropic mantle convection. We compare the evolution of flow patterns, Nusselt number and director orientations for isotropic and anisotropic rheologies. In the simulations we utilize two different finite element methodologies: The Lagrangian Integration Point Method Moresi et al [8] and an Eulerian formulation, which we implemented into the finite element based pde solver Fastflo (www.cmis.csiro.au/Fastflo/). The reason for utilizing two different finite element codes was firstly to study the influence of an anisotropic power law rheology which currently is not implemented into the Lagrangian Integration point scheme [8] and secondly to study the numerical performance of Eulerian (Fastflo)- and Lagrangian integration schemes [8]. It turned out that whereas in the Lagrangian method the Nusselt number vs time plot reached only a quasi steady state where the Nusselt number oscillates around a steady state value the Eulerian scheme reaches exact steady states and produces a high degree of alignment (director orientation locally orthogonal to velocity vector almost everywhere in the computational domain). In the simulations emergent anisotropy was strongest in terms of modulus contrast in the up and down-welling plumes. Mechanisms for anisotropic material behavior in the mantle dynamics context are discussed by Christensen [3]. The dominant mineral phases in the mantle generally do not exhibit strong elastic anisotropy but they still may be oriented by the convective flow. Thus viscous anisotropy (the main focus of this paper) may or may not correlate with elastic or seismic anisotropy.
Keyword Computer Science, Theory & Methods
Existence
Layers
Rock
Wave
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

 
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Created: Mon, 13 Aug 2007, 13:44:46 EST