Digital Science and Technology

Optimal urban mobility network design for sustainable space sharing between vehicles and soft transport modes

Nowadays, we are witnessing a rapid spread of multimodal mobility in our cities and a willingness on the part of communities to promote new mobility behaviors. These changes are causing road networks to evolve and grow with modifications that are often far from being optimally designed, and public authorities are beginning to investigate how to integrate new paths and roads for the new soft transportation modes (bicycles, e-scooters, etc.).

Hybrid High-Order methods for Phase-field modeling of fracture propagation

In this thesis, we are interested in the modeling of fracture propagation. Historical formulations have two types of drawbacks. In the case of local damage models, the limitations come from the fact that the results depend on the computational mesh. On the other hand, when each fracture is modeled independently, the limiting factor is the computational cost. The phase-field fracture modeling method has the advantage of being a continuous method that integrates naturally with Continuous Media Mechanics and the associated numerical tools.

Vectorisation portable avec maitrise de la précision numérique pour des codes de simulation multi-précision

The performance of simulators has a direct impact both on the quality of the simulation results and on the study of a wide variety of scientific hypotheses.

Modern parallel computing resources are based on complex hardware architectures with several levels of parallelism involving SIMD computing units. This level of parallelism is crucial since it significantly increases the number of floating-point operations per second. In this thesis, we focus on this level of parallelism by trying to attain the optimal performance of the computation kernels used in our applications. 

Scenario tree reduction and operator decomposition method for stochastic optimization of energy systems

The drop in production costs of distributed energy production systems and electrochemical storage systems coupled with the evolution of regulations make it possible to build local energy management operations. Development of such operations will be all the easier if the management systems allow the various involved players to reduce their electricity bills and/or their greenhouse gas emissions To this end, the various energy systems need to be optimized, a challenging task for mainly two reasons: First, the random nature of consumption/production.

Towards the modelling of high Prandtl number liquid cooling

The recent advent of electric vehicles is pushing car manufacturers to design more compact electric motors running at higher speeds, leading to higher local heat generation. Cooling is therefore crucial to preserve the efficiency and the reliability of the electrical machine. Innovative cooling systems based on oil jets directly impacting critical parts are then considered.

Augmented Large-eddy simulations of an internal combustion engine fueled with hydrogen

Electrification of vehicles and improved efficiency of internal combustion engines (ICE) are the main levers to reduce greenhouse gas emissions. The second priority of the French strategy for the deployment of low-carbon hydrogen is the development of renewable hydrogen for use in fuel cells or for combustion in a spark-ignition engine (SIE). However, for the latter technology, many challenges must be tackled before meeting real driving emissions expectation due to the diversification and complexity of hybrid applications.

New face-dependent packing microstructure model

Alumina-based catalyst supports are used for biomass conversion processes under development. They consist of multi-scale porous materials, obtained in most applications after calcination of boehmite powders (aluminum hydroxide precursor of alumina) and composed of dense alumina nano-platelets with complex arrangements. Modelling the physical phenomena dictating the arrangement of the nanoplatelets, with deterministic methods, is difficult and extremely expensive in terms of computational time, prohibiting the calculation of a sufficiently large representative volume of the microstructure.

Development of a robust adaptive mesh refinement method for Large Eddy Simulations: application to hydrogen deflagrations

 A significant reduction of greenhouse gases emissions is needed to keep global warming at an acceptable level in the next decades. In particular, the decarbonization of the energy and transport sectors is necessary and the use of hydrogen is a plausible solution as its consumption, through combustion processes or in fuel cells, is carbon-free. It may also provide flexibility to systems based on intermittent resources. However, hydrogen is a volatile and highly flammable compound. Its storage and use are associated with high risks of explosions which must be adequately addressed.