CENTRALE LYON - PhD thesis Development of Advanced Lattice-Boltzmann Simulations of Transonic and Transcritical Flows in Fatal-Heat Recovery Systems

Research field _____________________________________________
ECL and Laboratory presentation

Founded in 1857, École Centrale de Lyon is one of the top 10 engineering schools in France. It trains more than 3,000 students of 50 different nationalities on its campuses in Écully and Saint-Étienne (ENISE, in-house school): general engineers, specialized engineers, masters and doctoral students. With the Groupe des Écoles Centrale, it has three international locations. The training provided benefits from the excellence of the research carried out in the 6 CNRS-accredited laboratories on its campuses, the 2 international laboratories, the 6 international research networks and the 10 joint laboratories with companies. Its excellent research and high-level teaching have enabled it to establish double degree agreements with prestigious universities and advanced partnerships with numerous companies. With its focus on sobriety, energy, the environment and decarbonization, Centrale Lyon intends to respond to the problems faced by socio-economic players in the major transitions.

Research field presentation:

Description of the activities

Project Context: The REVCO2 Project - PEPR SPLEEN [1]

The intermittent nature of renewable energy sources highlights the need for diversification and optimization of energy recovery and conversion systems to ensure a stable and secure energy supply. Among potential energy sources, solar radiation, biomass combustion or gasification, geothermal heat, and industrial waste heat all play critical roles. One promising solution for harnessing these energy sources is the supercritical CO2 (sCO2) Brayton cycle, which offers high thermodynamic efficiency, compact equipment, and adaptability to a wide range of heat sources, including next-generation nuclear reactors and industrial waste heat. This PhD thesis is part of the PEPR REVCO2 project, a massive collaborative effort among four research laboratories (CETHIL, Lafset, LMFA and LUSAC) to fully develop a versatile reversible sCO2 Brayton cycle targeted to harvest industrial waste heat. In this project, LMFA Centrale Lyon focuses on global design of the turbomachinery stages.

PhD thesis Objectives and Methodology

This project is built upon the expertise of the research team (see e.g. Vienne et al. [2], 2024; Giauque et al., 2023 [3]). The PhD work is structured around the following key milestones:

1. Implementation and validation of real-gas model: Develop, verify and validate real gas equations of state capable of accurately representing the supercritical behavior of CO2.

2. Assessment and improvement of the solver: Identify the limitations of the current solver in regards to the global needs of the REVCO2 project. Propose, develop, and test enhancements (e.g., shock-capturing strategies or improved numerical schemes).

3. Idealized supersonic flow simulations: Using the optimized code, conduct idealized simulations of supersonic real gas flows.

4. Application to realistic configurations: Finally, perform simulations of realistic turbomachinery configurations.

Throughout the REVCO2 project, the PhD candidate will engage in exchanges with the other partners. The results obtained from the simulations of the realistic turbomachinery configurations will served as input data for the REVCO2 consortium, in particular for the turbomachinery design optimization process conducted by a parallel PhD student at LMFA.

The numerical solver involved is ProLB [4]. It is an innovative Computational Fluid Dynamics (CFD) software solution developed at LMFA in collaboration with academic and industrial partners fostering scientific breakthrough [5]. It has already been adopted by major industrial companies. The solver is based on the lattice-Boltzmann method and performs inherently unsteady simulations of highly complex flows with a competitive turnaround time.

[1] https://www.pepr-spleen.fr/en/accueil-english/
[2] Lucien Vienne, Alexis Giauque, Emmanuel Lévêque; Hybrid lattice Boltzmann method for turbulent nonideal compressible fluid dynamics. Physics of Fluids 1 November 2024; 36 (11): 116138. https://doi.org/10.1063/5.0234603
[3] Alexis Giauque, Dominik Schuster, Christophe Corre; High-fidelity numerical investigation of a real gas annular cascade with experimental validation. Physics of Fluids 1 December 2023; 35 (12): 126119. https://doi.org/10.1063/5.0174230
[4] https://www.prolb-cfd.com/
[5] https://www.prolb-cfd.com/documentation/

Required skills / qualifications________________________________

Diplomas: Engineering or Master graduates (in September/October 2026)

Experience:

Knowledge required: Strong background in fluid mechanics and numerical flow simulation. A significant part of the work will involve scientific programming, development of numerical methods, and in-depth physical analysis of flow phenomena. The ideal candidate is passionate about new opportunities offered by cutting-edge CFD methods.

Operational skills: Prior experience in CFD and/or CFD code development (e.g. Python, Fortran, C++) would be a considered as a strong asset

Behavioural skills: team player, creative but thorough

Work context/environment

The PhD project will be jointly supervised at LMFA by Lucien Vienne (CNRS engineer and specialist in Lattice Boltzmann Method), Alexis Giauque (associate professor at ECL and specialist in thermodynamics) and Emmanuel Leveque (CNRS research director and specialist in turbulence).

The doctoral candidate will benefit from regular meetings to closely support the progress of the research. The successful candidate will join a stimulating research environment and become part of a growing team working on ProLB and LBM including permanent researchers, three post-doctoral fellows and two additional PhD students.

The Laboratoire de Mécanique des Fluides et d’Acoustique (LMFA) is a major research actor in fluid mechanics and acoustics in France, and is located on the campus of École Centrale de Lyon (Écully, France) close to the city of Lyon.

Recruitment process_______________________________

The recruitment process takes place in two stages, supervised by a recruitment committee, in accordance with Centrale Lyon's OTMR policy.

• Study of the written application: CV + cover letter + transcripts for the current and previous academic years. One or more recommendations from teachers or supervisors would be appreciated.

• Selection interview: in person or by videoconference

Recruitment timetable: interviews will start on the 24th of February and extend until a suitable candidate is found. A security clearance must be issued after acceptance.

Selection criteria: academic results, fulfillment of the expected skills