A 3D finite element magma reservoir simulator

<p>IC-FEMRES (Imperial College Finite Element Magma REservoir Simulator), is a finite-element based numerical code for simulating the 3D dynamic behaviour of a two-phase, multi-component magma reservoir with chemical reaction.&#160; The code is built upon the open-source IC-FERST package (http://multifluids.github.io/) which includes advanced numerical features such as dynamic mesh optimization, to allow fine-scale solution features to be captured while simulating in a large domain.</p> <p>The model solves for velocity using a finite-element approach, and for transport using a control-volume scheme to ensure the conservation of energy, mass, and components.&#160; Solid, melt and volatile phases are modelled as Stokes fluids with very different Newtonian viscosities.&#160; Individual crystals in the solid matrix are incompressible, but the solid phase is compressible to account for changes in melt fraction.&#160; The formulation captures viscous compaction and convection of the solid matrix, and flow of melt and volatiles via a Darcy-type formulation at low melt fraction, and a hindered-settling type approach at high melt fraction. &#160;It also captures heat transport by conduction and advection, and component transport by advection.&#160; A chemical model is used to calculate phase fraction and composition.&#160; The numerical package sequentially solves for: 1. Melt and solid velocity (mass and momentum conservation); 2. Enthalpy and component transport (energy and component conservation); 3. Phase fraction and composition (chemical model). &#160;Material properties such as density and viscosity can be coupled to solution fields such as melt fraction and composition to yield a highly non-linear system of coupled equations that are solved iteratively.</p> <p>We demonstrate here the validation of the formulation against well-constrained test cases, and example results for a magma reservoir in the continental crust obtained using a simple two-component chemical model created by fitting a binary phase diagram to experimental melting data.&#160; Solutions show significant deviations from the predictions of 1- and 2D thermal models, or 1D models that include magma dynamics, and may explain some hitherto poorly understood aspects of magma reservoir formation, dynamics and chemical differentiation.&#160;</p>