MOVIES AND SHORT DESCRIPTION OF MY RESEARCH

My research in movies

ROTATING DOWNSLOPE INTRUSIVE GRAVITY CURRENT

2019 - TUBE

Top view of a axisymmetric downslope gravity current highlighted with fluorescent die injected with the saline solution at the top of the inclined conical boundary through 32 equally spaced injectors on the Coriolis Platform circumference. The total duration of the experiment is 3.5 hours, movie is reproduced 10x faster. Note the intrusion of saline water at the level of neutral buoyancy in the central deep area produces vortices of different size and sign.

GÖRTLER INSTABILITY?

2015 - CANAL

The spatial development on a concave boundary, more representative of natural
slopes, is very similar to that on a constant slope boundary, so that it is
rather the sudden slope change that causes the observed different behaviour
in the development of the gravity flow with respect to previously studied
constant velocity gravity flows on a slope (Negretti et al 2017).
Possible centrifugal instabilities
due to boundary curvature do not change the dynamics. Brun (2017) performed
numerical simulation of katabatic winds down a slope with a hyperbolic tangent
shape (first convex then concave) using the mesoscale model MesoNH code
developed at Météo France, coupled to a three-dimensional large-eddy simulation
parametrization. He reported the formation of Görtler instabilities in the outer part of the velocity profile (at the interface and above) where the density
stratification is weak, which modify vertical mixing and the vertical turbulent
transport. Albayrak, Hopfinger & Lemmin (2008) studied a wall jet on a concave
boundary and reported significant changes in the boundary layer characteristics when Görtler instabilities were present. We performed cross-stream slit lighting and dye injections at the boundary but could not detect any Görtler vortices near
the boundary for the parameter range investigated. Up to onset of KH instability,
the boundary layer has a low cD and Görtler vortices if present would only
increase cD by less than a factor of 4 (Swearingen & Blackwelder 1987).

DOWNSLOPE GRAVITY CURRENT

2017 - GRACCOT

Downslope gravity current highlighted in white by fluorescent dye over a hyperbolic tangent sloping boundary. Note the formation of Holmboe instabilities at the beginning of the slope, of the Kelvin_Helmholtz instability further downstream and of a turbulent shear layer at the end of the slope.

My research in movies: Recherche