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Towards a better modelling of deformation caused by magmatic mushes: Benchmarking a Computational Fluid Dynamics-Discrete Element Methods (CFD-DEM) models with analogue experiments

Alexandra Morand 1, Alain Burgisser2 , Alison C. Rust1, Gabriella Zmajkovic1, Juliet Biggs1

  • Affiliations:  1School of Earth Sciences, University of Bristol, Bristol, United Kingdom 2ISTerre, Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, Grenoble, France

  • Presentation type: Poster

  • Presentation time: Thursday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 188

  • Programme No: 1.8.19

  • Theme 1 > Session 8

Abstract

Observed deformation at active volcanoes results from complex interactions and coupling between the magma and the host rock. Fracturing of the crust during its deformation can make the pattern of surface displacement even more complex. Building models taking into account both the fluid and the solid phases and their interactions is a crucial next step to better understand the deformation observed in natural systems. We use the software MFiX (Multiphase Flow with Interphase eXchanges) which considers two phases: a fluid phase simulated with Computational Fluid Dynamics (CFD), and a solid phase composed of spherical particles computed using the Discrete Element Methods (DEM) method. In DEM, particles can be bonded together to simulate an elastic solid. Bonds can break at any time step, such that actual fractures can develop during the simulations. We present here the final step of the benchmarking of the newly implemented bonds in MFiX. We are testing the coupling between the fluid phase and the bonded packing of particle by reproducing two sets of analogue experiments. In these experiments, a spherical cavity was created in a block of gelatin and then inflated at constant flux until fluid-filled fractures started to propagate away from it. In the first set of experiments, the fluid buoyancy was varied, and in the second set the fluid viscosity was varied. We show that this new model has the potential to model the magma as a fluid phase and couple it to the elastic and brittle deformation of the surrounding rock.