Pause
Lecture
Moteur de recherche d'offres d'emploi CEA

Laminar-turbulent transition in a superfluid helium boundary layer H/F


Vacancy details

General information

Organisation

The French Alternative Energies and Atomic Energy Commission (CEA) is a key player in research, development and innovation in four main areas :
• defence and security,
• nuclear energy (fission and fusion),
• technological research for industry,
• fundamental research in the physical sciences and life sciences.

Drawing on its widely acknowledged expertise, and thanks to its 16000 technicians, engineers, researchers and staff, the CEA actively participates in collaborative projects with a large number of academic and industrial partners.

The CEA is established in ten centers spread throughout France
  

Reference

2019-11140  

Description de l'unité

IRIG/DSBT/LRTH

Position description

Category

Thermohydraulics and fluid mechanics

Contract

Internship

Job title

Laminar-turbulent transition in a superfluid helium boundary layer H/F

Subject

The aim of this training period is the experimental study of the transition to turbulence in a superfluid He boundary layer (below 2.17K) at the surface of an oscillating plate. Superfluid helium is often described a mixture of two independent components: the normal component is viscous and governed by the standard Navier-Stokes equation while the superfluid component is inviscid.
The way those two components interact to form a boundary layer is poorly documented. In particular, below a critical Reynolds number (often associated to a velocity in the literature), it is expected that only the normal component is influenced by the presence of the moving plate. It is one of the hypothesis we shall address during the training period.

Contract duration (months)

4 to 6 months

Job description

The aim of this training period is the experimental study of the transition to turbulence in a superfluid He (below 2.17K) boundary layer at the surface of an oscillating plate. Superfluid helium is often described a mixture of two independent components: the normal component is viscous and governed by the standard Navier-Stokes equation while the superfluid component is inviscid.

The way those two components interact to form a boundary layer is poorly documented. In particular, below a critical Reynolds number (often associated to a velocity in the literature), it is expected that only the normal component is influenced by the presence of the moving plate. It is one of the hypothesis we shall address during the training period.

The work shall be divided into 3 parts:

First the student will have to improve the experimental apparatus, mainly the automation of the driving motor and the guiding system for the oscillating plate.
Then the student will perform measurements, mainly based on "second sound acoustics". This is a powerful way to detect the appearance of turbulence. The vorticity in a superfluid boundary layer can be detected thanks to the attenuation of the temperature waves (aka second sound) it will provoke. Those waves, superfluid specific, are the manifestation of the propagation of heat. In our experiment we observe spontaneous standing second sound waves when the flow is switched on and one of the aims of the training period will be to determine their origin. For this purpose, the second sound detection which is currently achieved using an electro-acoustic receiver (known to also convert first into second sound) will be backed with a second thermometric sensor.
Finally the student is expected to process the experimental data using a high level programming language (Matlab/Octave or Python). This is a very important task of the training period.

Applicant Profile

Fluid dynamics, Computer programming. Basics in electronics.
Master student (M2)
Doctoral school of Physics , IMEP2

Position localisation

Site

Grenoble

Job location

France, Auvergne-Rhône-Alpes, Isère (38)

Location

Grenoble

Candidate criteria

Recommended training

M2

PhD opportunity

Oui

Requester

Position start date

03/02/2020