Research:
- Noble gas diffusion and the importance of complex geometry with application to geochronology and thermochronology (more info soon).
- Reactive porous media flow in pressure vs buoyancy-driven flows (more info soon).
- Calcium isotope fractionation during precipitation from stirred solution (more info soon).
- Melt extraction from the mantle, continental growth and volcanic flare-up episodes
- Magma chamber dynamics
- Conduit flow and eruption dynamics
- Multiphase fluid dynamics
- Clathrate destabilization
- Development of lattice Boltzmann numerical methods
Melt extraction from the mantle, continental growth and volcanic flare-up episodes (with Joe Dufek):
In this project, we investigate the role of crustal foundering in the generation of high melt fluxes from the mantle and test their ability to produce flare-up type magmatism. We use a multiscale numerical approach where the mantle flow response is calculated from a finite volume multiphase numerical model...
and the production and extraction of melts is calculated with a combined crystal nucleation and growth algorithm and a lattice Boltzmann 3D porous media flow (to parameterize the evolution of the permeability)...
Magma chamber dynamics (with Olivier Bachmann and Michael Manga):
I am working on several projects related to magma chamber processes trying to address the following questions:
- What controls the homogeneity (temperature, crystallinity and major element composition) of crystal-rich silicic eruptions ?
- How do crystal mushes get reactivated prior to an eruption ?
- What is the role of volatiles degased from an underplating intrusion in the reactivation of crystal-rich magmas (mushes) ?
- What controls the lack of erupted crystal-rich ignimbrite in "dry" tectonic environment (extension, hot-spot) ?
- What controls the transition from a crystal slurry (suspension) to a crystal mush (behaves like a solid) ?
Figure showing the different regimes controlled by the injection of volatiles exsolved by a cooling underplating magma (with various initial water contents x-axis) on the reactivation of crystal mushes with different composition (y-axis):
Conduit flow and eruption dynamics (with Joe Dufek and Andrea Parmigiani):
The explosivity of volcanic eruptions is controlled by the viscosity of the magma and the ability of volatiles to escape the magma during its ascent in the conduit. Together with Joe Dufek, we are developing a multiscale numerical approach to include effects such as bubble coalescence, deformation and the development of percolating gas pathways and outgassing. We parameterize the evolution of the bubble size distribution due to coalescence and bubble deformation with a 3D multiphase lattice Boltzmann model...
These parameterizations are then used in the 2D multiphase transient conduit flow of Dufek and Bergantz (2005).
Multiphase fluid dynamics (multiple projects...):
Together with Jim Watkins and Michael Manga, we calculated the shape of a buoyant bubble ascending along a sloping boundary at low Reynolds number (and in the miscible limit). Experimentally, we found that the shape of the bubble at steady-state is independent of the slab angle (when >0 and < 40 degrees). We used a Boundary Integral Method and scaling arguments which confirmed the experimental results.
ascending bubble... (picture J. Watkins)
I am also investigating the development of capillary instability during the injection of a buoyant non-wetting fluid phase in a saturated porous medium. I predict from theoretical arguments that the non-wetting phase will get channelized even in an homogeneous porous medium because of capillary effects. Together with Andrea Parmigiani and Jonas Latt, I am developing a lattice Boltzmann model to test this instability on Teragrid super-computers.
Clathrate destabilization (with Wendy Mao and Bruce Buffett):
This project is about to start. We are interested to quantify the mobility of methane in a saturated porous medium during the destabilization of clathrate reservoirs during climate changes. To address this question we plan on using X-ray tomography images of real sediments and use a multiphase lattice Boltzmann model to quantify the motion of methane through the porous medium. Snapshots of multiphase flow in a porous medium - in red -, with the buoyant bubbles in blue:
Development of lattice Boltzmann numerical methods (with Andrea Parmigiani and Bastien Chopard):
The different projects I am involved in often require the development of new numerical techniques, moslty based on the lattice Boltzmann method. For instance, I developed a model for fluid flow and melting-solidification (see publications)... here convection melting in a square enclosure heated from the left (color coding for temperature)
Dispersion of diffusing chemical solutes (coupled through charge balance) in porous media flow (flow form the left)...
Compositional Rayleigh-Taylor instabilities triggered by solute concentration gradients (diffusing from the top). The different ions are coupled through charge conservation.
