Taylor bubble flow (known also as slug-plug or segmented flow) involves 
elongated bullet-shaped gas bubbles moving in a fluid-filled tube. While
the bubble moves in such a tube, a liquid film forms between the heated wall and 
the liquid-vapor interface. The film thickness can range from a few up to 
several tens of μm. Such thin films present a low resistance to the heat 
transfer from the wall towards the liquid-vapor interface thus providing
strong heat exchange at evaporation or condensation. Taylor bubble flow is 
therefore a desired flow pattern inside capillaries aiming at high heat transfer 
capabilities. The transferred heat flux is however limited by the film drying 
that occurs at strong evaporation. 

The physical understanding of such a flow requires the comprehension of several 
micro- and nanoscale physical phenomena such as liquid film flow, the contact 
line dynamics at dewetting, and liquid-vapor interface instabilities. Even 
though a wide range of studies are available in the existing literature, precise 
measurements of the liquid film dynamics and the interaction of two Taylor 
bubbles following each other are some examples of still lacking knowledge. In 
this context, a novel experimental installation has been developed to study 
Taylor bubbles rising in a capillary channel. In this particular setup, we aim 
at exploring the fundamental aspects of the film formation, the thickness 
profile along the bubble and its dynamics during the film drying. The wall 
temperature and heat flux distribution will also be studied.

The student will be based at the Laboratory of thermal hydraulics and fluid 
mechanics (STMF) of the Alternative Energies and Atomic Energy Commission of 
France (CEA), Paris-Saclay center, where the experimental and theoretical work 
will be carried out in close collaboration with the Laboratory of
Condensed Matter Physics (SPEC/CEA). The PhD student will benefit from the 
experimental expertise developed at CEA on novel non-intrusive high-speed 
techniques such as white light/laser interferometry and infra-red thermography 
that will be employed. The use of these techniques will allow the student
to master top notch scientific equipment, such as fast cameras, spectrometers, 
flow sensors and light sources. The PhD student will also collaborate with 
Professor Mirco Magnini from the University of Nottingham (United Kingdom), whom 
he/she will visit to work on a numerical model that simulates the motion of the 
Taylor bubble with the OpenFOAM freeware. Its results will be compared to the 
experimental data.

Candidate profile: The candidate is a student who has a knowledge on fluid 
mechanics and thermal science and, preferably, on optical measurements and 
numerical simulations. He/She is highly motivated to perform both experimental 
and numerical work. Programming skills using matlab are required.
Fluency on English is required.

The position: Fully funded 3-years doctoral contract with CEA Paris-Saclay 
starting from September-November 2024.