PhD Thesis Offer at the University of Lille and IMT Nord Europe – October 2025

Title: Thermo-Convective Instability in Suspension Flow (THECOS)

Context and Objective:
The intensification of energy exchanges is a major challenge for 
decarbonization: how can we efficiently regulate the
thermal behavior of industrial or electronic components while minimizing the 
energy required for this regulation? The
THECOS project focuses on the study of heat transfer in dispersed media as a 
tool for this intensification, allowing the
promotion and/or control of convective-conductive instabilities and transfers. 
The influence of the physical and
morphological properties of particles on heat transfer will be studied in 
relation to the various dynamic phenomena
associated with two-phase flow: hydrodynamic instabilities, secondary flows, 
migration of the dispersed phase, and the
transfer of heat and kinetic energy.

The PhD project is structured into two complementary phases:

1. Theoretical and Numerical Analysis:
The PhD candidate will conduct theoretical and numerical
studies in linear and weakly nonlinear flow regimes to
determine the thresholds and characteristics of instabilities
that a particulate two-phase fluid may present when subjected
to a thermal gradient. Direct numerical simulations (DNS)
will be carried out to further explore the dynamics and
transfers beyond the convection threshold, as well as in
strongly nonlinear and turbulent regimes. This phase will be
supervised by the Complex Fluids team at UML.

2. Experimental Study:
The PhD candidate will conduct an experimental investigation in the Complex 
Fluid Flow laboratory of CERI
EE, which specializes in characterizing the dynamics of complex fluid and 
suspension flows. The experiments
will use a Rayleigh-Bénard cell adapted for particle injection and will focus on 
analyzing instability
phenomena, particle segregation, and convective intensification of heat 
transfer. A comparison with numerical
results will help validate the physical model and simulation outcomes.

Organization and Required Skills:

This PhD project will be supported by a strong collaboration between the Lille 
Mechanics Unit and the Energy &
Environment Center. It will take place at the Lille and Douai sites and will be 
funded by the Hauts-de-France region in
partnership with both institutions.
The thesis is aimed at students with a background in physics, fluid mechanics, 
or thermal sciences who are interested in
combining analytical, numerical, and experimental approaches. Knowledge of 
rheology, complex fluid dynamics, and
two-phase flow would be beneficial but is not a prerequisite.

Supervisors:

Silvia HIRATA (University of Lille), Enrico CALZAVARINI (University of Lille), 
Amir BAHRANI (IMT Nord
Europe) Tom LACASSAGNE (IMT Nord Europe)

Application Procedure:

Send a detailed CV, a cover letter, the names and emails of at least two 
referees willing to provide a recommendation
letter, and any other supporting documents to: 
silvia.hirata@univ-lille.fr, amir.bahrani@imt-nord-europe.fr