April 19, 2024
16:15
Louvain-la-Neuve
Place Sainte Barbe, auditorium BARB 92
Understanding and predicting the hydrodynamics of river systems is a challenging, yet crucial task for managing the land-sea continuum. Considering the goal of maintaining an acceptable accuracy level with acceptable calculation time, various modeling approaches can be investigated to address this challenge. This thesis contributes to enhancing the robustness of the one-dimensional component of SLIM (www.slim-ocean.be) by focusing on improving its reliability and performance through several key contributions. Firstly, the thesis introduces the Discontinuous Galerkin (DG) discretization method for the 1D Saint-Venant equations, emphasizing the importance of carefully selecting the momentum conservation equation to solve. We present a uniform approximate Riemann solver to deal with the different types of interface nodes: simple internal nodes, confluences, and boundary nodes. Special attention is given to 1D-2D external boundary connections for larger water bodies, enhancing the model's applicability for large-scale river-delta continuum simulations. To address stability issues that may arise due to non-smooth source terms and ensure robustness in modeling subcritical flows, we focus on coherence between longitudinal and vertical evolution of channel geometries, introducing the concept of a global datum description. We also compare linear and quadratic spline longitudinal interpolation schemes, demonstrating their impact on model accuracy and convergence rates. Particular focus was given to model validation and calibration on idealized test cases before tackling real-life flow scenarios. These improvements enhance SLIM's capabilities, making it more applicable to complex river networks. In this thesis, flow in the Mahakam river-delta-sea continuum is dealt with, and, on the other hand, the same model is used in the framework of another research project, 
aimed at modeling the Scheldt estuary, rivers, and the European continental shelf with hydraulic structures explicitly represented in the river network.
Jury members :
- Prof. Eric Deleersnijder (UCLouvain, Belgium), supervisor
- Prof. Vincent Legat (UCLouvain, Belgium), supervisor
- Prof. Hervé Jeanmart (UCLouvain, Belgium), chairperson
- Dr. Jonathan Lambrecht (UCLouvain, Belgium)
- Prof. Jean-Marie Beckers (ULiège, Belgium)
- Dr. Sébastien Legrand (Royal Belgian Institute of Natural Science)