Description du poste

The ability to predict sediment transport is a major societal issue for the management of natural systems in order to limit and prevent impacts related to climate change and to anthropogenic activities such as tourism and development (bridges, dams, ports, dykes and other structures ...). Responding to these issues requires the development of new models that take into account the various hydro-sedimentary processes such as interactions with turbulent macrostructures, inter-particle collisions or friction. These complex, and still poorly understood phenomena, are not integrated into current engineering models, which hinders their predictive capacity. Improving these models meets a strong expectation of local and national decision-makers for the management of asset and risk. In the context of this internship, the problem of scouring around obstacles such as bridge piers will be used as an application problem in connection with the concerns of the engineering company ARTELIA. The long-term goal of is to develop more accurate sediment transport models that integrate complex physical processes to improve the predictive capacity of engineering models.

The objective of the internship is to evaluate different numerical models to simulate scouring phenomena around hydraulic structures such as bridge pile in rivers or wind turbine foundations at coasts. The evaluation will be performed on different configurations ranging from idealized laboratory experiments to field scale applications. The numerical models to be evaluated are two open source softwares, openFOAM and openTELEMAC.

The first task of the internship will be to carefully evaluate the flow dynamics by performing various simulations using different grids and different turbulence model (e.g. k-omega SST). Experimental data from Sumer et al. (1997) for waves and Roulund et al. (2005) for currents will serve as a benchmark. A special attention will be paid to the prediction of the bed shear stress which is the driver of sediment transport.

The second task will be focused on the simulation of sediment transport and bed morphological evolution. In openTELEMAC, the sediment transport module is fully operational however for openFOAM no official sediment transport module exists. The intern will evaluate existing (non-official) open-source sediment transport modules for openFOAM by testing academic benchmarks following the same strategy as in Lesser et al. (2004) or Warner et al. (2008). If there is enough time, both openTELEMAC and the coupled openFOAM – sediment transport model will be applied to scour around a vertical cylinder. Otherwise, only openTELEMAC will be evaluated.

- Theoretical: fluid mechanics, turbulence, sediment transport