Section: New Results

Marine and coastal systems

Numerical Modelling of Hydrokinetic Turbines

Recent studies have pointed out the potential of several coastal or river areas to provide significant energy resources in the near future. However, technological processes for extracting energy using Marine Current Energy Converters (MCEC) are not generically "field-ready" and still require significant research to be set up. The book chapter [8] comes within this framework: we develop the numerical model OceaPoS, useful to carry out a comprehensive description of turbulent flow patterns past MCEC and forward optimize the turbine arrays configurations and evaluate their environmental effects. The OceaPos model consists in describing the fluid as an ensemble of Lagrangian particles ruled by a Stochastic process. OceaPos follows the same methodology than SDM-WindPoS model for wind farm simulations and adapts the Lagrangian stochastic downscaling method (SDM) to the tidal and oceanic boundary layer. We also introduce a Lagrangian version of actuator discs to take account of one or several MCEC's devices and their effects on the flow dynamics. Several benchmarks are presented, and numerical predictions are compared to experimental results.

Multi-scale ocean modeling

In [3], we derive discrete transparent boundary conditions for a class of linearized Boussinesq equations. These conditions happen to be non-local in time and we test numerically their accuracy with a Crank-Nicolson time-discretization on a staggered grid. We use the derived transparent boundary conditions as interface conditions in a domain decomposition method, where they become local in time. We analyze numerically their efficiency thanks to comparisons made with other interface conditions.

In Cemracs 2019 in Marseille, Joao CALDAS was enrolled in the project "Model analysis for tsunami generation by landslides", with Louis EMERALD (PhD student, Université de Rennes), Emmanuel AUDUSSE (maître de conférences, Université Paris 13), Martin PARISOT (chargé de recherche, Inria Bordeaux, CARDAMOM team), Philippe HEINRICH (researcher, CEA) and Alexandre PARIS (PhD student, CEA). The project, funded by CEA, aims to study and compare different fluid mechanics models (Navier-Stokes, Boussinesq, Shallow Water equations) in the simulation of waves generated by landslides. The observed behaviour of the models is correlated to the amount of energy transferred from the sediments to the fluid, both in the wave generation zone (next to the landslide) and in the wave propagation zone (far away from it). An inverse problem is proposed for recovering the landslide from a given evolution of the free surface elevation. A publication will appear in the proceedings of CEMRACS 2019.