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Sujet de stage / Master 2 Internship

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Liquids at low frequency: a no-man’s land to discover

Contact: NOIREZ Laurence, , laurence.noirez@cea.fr, +33 1 69 08 63 00/62 22
The identification of low frequency shear elasticity in liquids is a novel parameter which makes possible the highlight of new phenomena. Cooling by flow is now become possible.
Possibility of continuation in PhD: Oui
Deadline for application:14/04/2018

Full description:
Liquids at low frequency: a no-man’s land to discover

Liquid state: A nearly incompressible state that conforms to the shape of its container…
Our advances prove that this simple definition is not valid and since the liquid requires a container, interfacial interactions are introduced and care…
Since the Maxwell gas model (1867), liquids are assumed to exhibit a solid (shear) elastic response only at sufficiently high frequency (MHz or GHz). Recent experimental developments at the Laboratoire Léon Brillouin show that it is now possible to measure an elasticity also at low frequencies (Hz or less), in other words liquid molecules are no more dynamically free but correlated at long range. The discovery of low frequency shear elasticity is a major observation since it calls into question a dogma in the dynamics of liquids, the flow of a fluid is no longer linked to a molecular relaxation time. The low frequency shear elasticity is a novel parameter in liquids which requires revisiting hydrodynamic models and classical rheology, and makes it possible to highlight new phenomena such as cooling by flow. Collaborations with several national and international teams (Institut de Physique du Mans, Cambridge Univ., TU-Berlin) are already in place to pursue this experimental approach of liquids using dynamic relaxation, IR-emissivity or scattering techniques. Solid skills in liquid physics, physico-chemistry or materials are necessary together with a strong motivation for the development and the use of experimental setups.
1. L. Noirez et P. Baroni, Identification d'un comportement élastique à basse fréquence dans l'eau liquide, Journal of Physics: Condensed Matter 24: 372101, 2012.
2. P. Baroni, P. Bouchet, L. Noirez, Highlighting a Cooling Regime in Liquids under Submillimeter Flows, J. Phys. Chem. Lett. 4 (2013) 2026.

Contact: L. Noirez (laurence.noirez@cea.fr), Laboratoire Léon Brillouin (CEA-CNRS), Univ. Paris-Saclay.
Technics/methods used during the internship:
Dynamic relaxation, infra-red emissivity, scattering methods.

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