The production of electricity through nuclear energy plays a crucial role in the energy transition due to its low carbon impact. To continuously improve safety and performance, it is essential to develop new knowledge and tools.
The core of a nuclear reactor consists of thousands of fuel rods traversed by a turbulent flow. This flow can cause vibrations, leading to wear. Two flow scales are identified: a local scale, where the fluid interacts with the rods, and a global scale, representing the flow distribution within the core. The local scale requires CFD simulations and fluid-structure coupling, while the global scale can be modeled using averaged approaches, such as porous media simulations.
Coupled fluid-structure interaction (FSI) simulations at the CFD scale are limited to small domains. To overcome this limitation, multi-scale approaches are required, combining large-scale porous media simulations and detailed small-scale CFD simulations. The goal of the thesis is to develop methods for synthesizing turbulence from the results of porous media simulations to improve boundary conditions for CFD simulations. The candidate will first study how existing turbulence models can provide details on turbulent flow at the component scale, and then how to synthesize turbulence for local CFD simulations.

This PhD project is the subject of a collaboration between the IRESNE Institute (CEA) and the ASNR (main execution site of the thesis) in Cadarache. Funding is provided by a MSCA Doctoral Network. The PhD student will be integrated into a network of 17 PhD students. To be eligible, the candidate must have resided no more than 12 months in the last 36 months in France.