PHD scholarship Hydrodynamics of bubble columns at large void fractions

Organisation/Company Centrale Lille Institut Department North Research Field Engineering Researcher Profile First Stage Researcher (R1) Positions PhD Positions Application Deadline 23 Mar 2026 - 23:59 (Europe/Paris) Country France Type of Contract Temporary Job Status Full-time Is the job funded through the EU Research Framework Programme? Not funded by a EU programme Is the Job related to staff position within a Research Infrastructure? No

Offer Description

Topic: This PhD project aims to investigate the emergence of large-scale structures and the transitions leading to the fully heterogeneous regime in bubble column reactors. These systems are fundamental to many chemical, environmental, and energy applications, yet their hydrodynamics remain poorly understood due to the complex interplay between the dispersed gas phase, the continuous liquid phase, and the evolving interfaces between them. The candidate will conduct a series of experiments designed to clarify the mechanisms governing flow organisation, regime transitions, and turbulent mixing.

The experimental study will rely on complementary facilities. At LMFL, the candidate will use a large bubble column with a 60 cm diameter and 5 m height, currently under construction, which will operate with void fractions between 5% and 40% and bubble diameters typically ranging from 2.5 to 5 mm. This unique setup will allow the exploration of global flow structures, large-scale recirculation, and the transition to the fully heterogeneous regime under realistic industrial conditions. In parallel, smaller-scale experiments will be conducted at IMFT in 10–20 cm square columns, where gas injection can be finely controlled using a matrix of capillary tubes. This configuration enables precise control over the bubble size and spatial distribution, making it possible to induce and study different flow regimes (from homogeneous to highly heterogeneous) and to observe the transitions between them. These controlled conditions are particularly suitable for detailed comparisons with high-fidelity numerical simulations. Additionally, LEGI lab has a similar reactor to that of LMFL (operational and fully instrumented) that may also be used within the project.

Characterising bubble column hydrodynamics experimentally presents major challenges, particularly at large void fractions where the flow becomes opaque and standard optical techniques fail. At low void fractions, in the homogeneous and dilute regimes, techniques such as laser Doppler anemometry, hot-film anemometry, particle image velocimetry, particle tracking velocimetry, and intrusive optical probes will be used to measure both liquid and gas phase properties. As the void fraction increases and the heterogeneous regime develops, the range of available measurement techniques becomes more limited. In this regime, the project will employ Pavlov tubes, devices analogous to Pitot probes but capable, after suitable calibration, of measuring both upward and downward liquid velocities. To characterise the gas phase at high void fractions, the project will also use a recently developed optical sensor that combines phase detection with Doppler-based velocity measurements.

The combination of these diagnostic techniques, applied across different experimental scales, will allow the PhD candidate to investigate a broad parameter space and to generate datasets of exceptional value. Small-scale experiments will offer high-resolution measurements ideally suited for comparison with detailed numerical simulations, while large-scale experiments will provide data relevant to coarse-grained modelling of regime transitions. The project will thus contribute new physical insight into the mechanisms governing the organisation and dynamics of bubble column reactors, while providing high-quality datasets for the broader research community. The student will receive comprehensive training in advanced experimental techniques, data analysis, and multiphase flow physics, preparing them for careers in both academic and industrial research.

Location: The PhD will take place at LMFL lab in the University Campus of Villeneuve d’Ascq. The candidate is expected to perform research visits at both LEGI (Grenoble) and IMFT (Toulouse).

Funding: the scholarship is fully funded within an ANR project, including IMFT Toulouse, CEA STMF.

Starting date : spring 2026 (open to discussion).

Candidate : The PhD candidate must hold a Masters’ degree in fluid mechanics, physics or applied mathematics and have a good knowledge in fluid dynamics, with an interest in experiments and turbulence.

Application process: Applicants should send a CV and motivation letter to the direction team. Recommendation letters may also be included in the application.

References :

Mezui, Yann, Martin Obligado, and Alain Cartellier. "Buoyancy-driven bubbly flows: scaling of velocities in bubble columns operated in the heterogeneous regime." Journal of Fluid Mechanics ): A10.

Mezui, Yann, A. Cartellier, and Martín Obligado. "An experimental study on the liquid phase properties of a bubble column operated in the homogeneous and in the heterogeneous regimes." Chemical Engineering Science ): .

Obligado, Martín, Mark Terentyak, Alain Cartellier, Zhujun Huang, Marek C. Ruzicka, and Sandra Orvalho. "Time-dependent hydrodynamics of bubble columns."Chemical Engineering Science ): .

Zamansky, Rémi, Florian Le Roy De Bonneville, and Frédéric Risso. "Turbulence induced by a swarm of rising bubbles from coarse-grained simulations." Journal of Fluid Mechanics ): A68.