> C. Morize
Research: Erosion and Resuspension of Granular Bed, Convection
- Destabilization of an immersed granular bed by thermal convection, in collaboration with E. Herbert (LIED) and A. Sauret (SVI).
The transport, dispersion and resuspension of particles
occur in industrial fluid dynamical processes as well as environmental and geophysical situations. Whereas
the resuspension of an immersed granular bed by fluid flows such as vortices or shear flows has been
the focus of many studies, the ability to fluidize particles with a vertical gradient of temperature remains
poorly understood. Using laboratory experiments with a localized heat source, we observe that a massive
entrainment of particles into the fluid volume occurs beyond a threshold temperature. The buoyancy driven
fluidized bed then leads to the transport of solid particles through the generation of particle-laden plumes.
- Propulsion in the vicinity of a granular media,
in collaboration with A. Sauret (SVI) and P. Gondret.
In various situations, sand and sediments can be carried by wind or
water, which could trigger the resuspension of the granular bed. For instance, when a helicopter lands in
sandy environments, its blades trigger air recirculation which leads to the resuspension of particles, thus
limiting the pilot's visibility. Here, we focus on a unique situation, in which the resuspension of particles
is both sought after and well controlled. Indeed, some bottom-dwelling fish, such as the flounders and stingrays,
generate a flow capable of resuspending sand to bury themselves and avoid predators. By flapping their fins with
oscillating motions, they create vortices and a recirculating flow that lifts the sand particles up and deposits
them on top of their backs. A simple model experiment has been developed to study this situation: a rigid or flexible
foil is placed above the sand bed to mimic the fin motion.
- Erosion in the vicinity of structures,
in collaboration with F. Lachaussée (PHD student), Y. Bertho,
A. Sauret (SVI) and P. Gondret.
transport of earth material is a leading threat for
human activity and ecosystems. For instance, at the pier of a bridge, erosion can damage the entire
structure leading to bridge failure. Achieving better hazard assessment requires coupling both the fluid
dynamics around the structure (instabilities, wall effects) and the transport phenomena of solid materials.
In this project, we propose to characterize the dynamics of entrainment of particles in the presence of flow
in the vicinity of solid submerged structures (bridge piers, offshore structures, ...) using experimental
approaches and mathematical models.
- Tsunami generated by granular collapse,
in collaboration with A. Sauret (SVI), A. Hildenbrand
(LGMT), Y. Bertho and
A tsunami is a wave that can propagate over
long distances and can lead to considerable damage along the coast. These situations showed the
necessity to predict or at least to evaluate the risk associated with such extreme events. In particular, whereas
the most common trigger for a tsunami is a submarine earthquake, other geological events can be involved. For
instance, landslides or cliffs collapse result in tsunamis that lead to important local hazards and need to be
understood and predicted. The experimental set-up will be developed to model this situation in 2D by generating
a granular collapse into a layer of fluid. The influence of the size and shape of the collapse, the water depth
as well as other relevant physical parameters (density of the granular material, sphericity, ...) will be
experimentally investigated and modeled.
Past research: Turbulence, Rotating fluids
- Zonal winds driven by tides, in collaboration with M. Le Bars (IRPHE), P. Le Gal (IRPHE) and A. Tilgner (Institute of Geophysics, University of Götttingen).
- Turbulent transport in tokamaks, in collaboration with P. Hennequin (LPP).
- Inertial waves in rotating flows , with L. Messio (LPTMC), F. Moisy and M. Rabaud.
- Coriolis platform experiments, in collaboration with F. Moisy and J. Sommeria (LEGI).
- Rotating turbulence (PhD thesis , supervised by F. Moisy and M. Rabaud, 2006, FAST, Orsay).
Citations (google scholar)