Public Thesis defense - IMMC

Numerical simulation of natural convection in mixed porous/pure-fluid domains by Victoria Hamtiaux

Pour l’obtention du grade académique de Doctorat en sciences de l’ingénieur et technologie

This thesis is dedicated to the exploration of natural convection phenomena within domains characterized by a heat-generating porous matrix immersed in a pure-fluid region. Such flows hold particular significance in various contexts, notably in the context of Loss-of-Cooling Accidents (LOCA) occurring within Spent Fuel Pools (SFP) in nuclear power plants.

In this application, the porous medium models the fuel assemblies placed in storage racks at the base of the water pool. During a LOCA event, the cooling circuit, responsible for maintaining low temperatures in the pool, becomes inoperative, leading to a free convection regime within the pool.

The Fukushima accident in 2011 exposed our limited comprehension of the intricate processes that take place during LOCA events. This research aims to address this knowledge gap by producing accurate data on the fundamental physics that govern flow dynamics and heat transfer in this context. This objective is of great interest to the research community involved in industrial numerical simulations of SFP during LOCA scenarios.

In order to achieve these goals, we have developed a numerical tool for conducting Direct Numerical Simulations (DNS) of three-dimensional natural convection within mixed domains of porous and pure fluids, featuring an internally heated solid matrix. The tool has been validated against a large set of cases, and its numerical properties have been studied.

By doing so, we perform a sensitivity analysis on the parameters that drive the physical modeling of the porous medium, providing valuable insights into the intricate dynamics of fluid flow and heat transfer in such a configuration.

The investigation extends to exploring the effects of altering rack heights relative to the bottom wall on the flow, namely on the Large-Scale Circulation (LSC) developing above the porous medium. Furthermore, the study delves into the consequences of uneven heat load distribution within the racks.

This comprehensive examination contributes valuable insights and paves the way for an enhanced understanding of LOCA phenomena.

Jury members :

Prof. Yann Bartosiewicz (UCLouvain), supervisor
Dr. Pierre Ruyer (IRSN, France), supervisor
Prof. Aude Simar (UCLouvain), chairperson
Prof. Grégoire Winckelmans (UCLouvain), secretary
Dr. Matthieu Duponcheel (UCLouvain)
Prof. Michel Quintard (IMFT, France)
Dr. Sofiane Benhamadouche (EDF, France)

Pay attention :

The public defense of Victoria Hamtiaux scheduled for Wednesday 24 January at 04:15 p.m will also take place in the form of a video conference

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