Using a strong magnetic field to study the Rayleigh-Taylor instability
Mardi 12 mai 2015 13:30
- Duree : 1 heure
Lieu : LNCMI, salle de conférences "René Pauthenet" (bâtiment J, 2ème étage) - 25 rue des martyrs - 38000 Grenoble
Orateur : Richard HILL (Notthingham University, UK)
The Rayleigh-Taylor instability (RTI) is a fundamental fluid instability that occurs at the interface between a dense fluid supported by a lighter one, under gravity (or equivalently, in a system that is accelerated in the direction of the denser fluid). An example is salt water lying on top of fresh water. In this configuration, the system is in mechanical equilibrium, but the equilibrium is unstable : small perturbations of the interface grow with time and quickly develop into large-scale finger-like intrusions of one liquid into the other, as the salt water sinks through the fresh water.
The RTI has remained a topic of interest in fluid dynamics owing to its common occurrence in industrial applications, in natural phenomena and for its intrinsic mathematical interest.
In studying the RTI experimentally, a difficulty arises in maintaining the stability of the heavy fluid above the lighter fluid during preparation of the system. Rapid acceleration or barrier methods can be employed, but each of these methods have their own weaknesses.
In this talk I will discuss an alternative method to initiate the RTI from equilibrium conditions, which makes use of an inhomogeneous magnetic field to apply differential magnetic forces to a two-fluid system. I will discuss how this method enables us to study the evolution of the RTI under rotation, which we find has the effect of inhibiting the growth of the instability owing to the Coriolis force.
Contact : anne-laure.barra@lncmi.cnrs.fr
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