Non-thermal equilibrium two-phase flow: General formulation and application to the lithosphere-asthenosphere boundary

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Within the framework of 3 month sabbatical leave at Monash University (Melbourne, Australia) the existing theory of two phase flow of magmatic systems will be extended to account for non-thermal equilibrium conditions. Migration of melt in a partially molten mantle region is usually described and modelled by porous flow of a low viscous fluid through a highly viscous deformable matrix. The length scale of the porosity is assumed sufficiently small (grain scale) so that thermal equilibrim between matrix and melt is maintained. However, due to various processes such as channeling or dyke formation this length scale may be increased, resulting in a non-thermal equilibrium between the melt and matrix. Because in the general case the matrix and melt move with different speeds and directions, this disequilibrium depends on the history of melt and matrix flow, i.e. a new theoretical formulation is required to describe the energy conservation of this system. In this project such a forumlation will be developed, simplifications will be tested and applied to the partially molten region near the lithosphere-asthenosphere boundary (LAB). The expertise of the hosts at Monash (Prof. R. Weinberg, Prof. A. Cruden) in the field of magmatic systems provides an excellent environment for cooperation in this project.