Contexte
General context
Mobility of the sedimentary substrate, both through the flow of sedimentary particles and through the migration and evolution of sedimentary structures, has direct implications on the design, implementation, longevity and safety of MRE (marine renewable energy) devices. Marine dunes are among the most dynamic sedimentary bodies and are frequent on the English Channel and North Sea coast where most of the future Europeans offshore windfarms (OWF) will be located. Dune mobility can bring risks of scouring around foundations. On the other hand, dunes are sedimentary habitats of high ecological importance. It is therefore crucial to understand the interactions between offshore windfarm foundations and mobile dunes, in order to protect both the infrastructures and the
ecosystem.
In the framework of France Energies Marines project MODULLES (2021–2024), a series of numerical and physical models will be developed to evaluate sediment thickness variations and scouring in a marine dune field in order to limit the impact on the OWF structures, and to assess dune resiliency to OWF structures deployment.
To date, most of the physical experiments conducted on subaqueous dunes have been performed under unidirectional steady current (Southard and Boguchwal, 1990; Kleinhans, 2004; Schindler and Robert, 2005; Naqshband et al., 2014, Vah et al., 2020). Some studies did focus on the effect of unsteady unidirectional flows on sediment deposition and dune internal structures (Reesink and Bridge, 2007, 2009). However, flume studies dealing with wave/current interactions are scarce (Cataño–Lopera and García, 2006; Chatterjee et al., 2019) and to our knowledge, there has not yet been flume experiments investigating dune formation and dynamics under reversing currents.
Therefore, there is a need to conduct experiments on dune development under combined wave and current flows and unsteady / reversing currents. Moreover, experiments investigating live–bed scour under complex hydrodynamics is quite limited in the literature (Chen and Li, 2019).
Description du poste
Missions / Activities
The post–doctoral fellow will carry out the following activities:
– Review the literature on dune physical modelling and live–bed scour experiments;
– Conduct flume experiments on dune equilibrium morphology and dynamics under unidirectional currents and wave–current interactions;
– Conduct flume experiments on live–bed scour processes around a cylindrical pile under current and wave–current interactions;
– Perform the processing and analysis of the experimental data (bed morphology, stress gauges, hydrodynamics)
– Perform statistical processing methods aiming at highlighting the probability density function of extreme events / current interaction
– Participate to the writing of reports and scientific publications, and presentation of the results to meetings, workshops and conferences.
A twin post–doc position will be opened at Le Havre university (LOMC lab.), focussing on dune development and scouring around monopiles under unsteady and reversing currents. The position offered here in Caen will focus on wave–current interactions. The two post–doctoral fellows are expected to work closely and to maintain a high level of interactions.
Modalités de candidature
Please send a CV, a letter of interest (up to one page long), and the names of two potential referees, to Nizar Abcha (nizar.abcha@unicaen.fr) and Pierre Weill (pierre.weill@unicaen.fr)
