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Reference : UMR6614-THIBES-006
Workplace : ST ETIENNE DU ROUVRAY CEDE
Date of publication : Monday, August 19, 2019
Type of Contract : FTC Scientist
Contract Period : 12 months
Expected date of employment : 1 October 2019
Proportion of work : Full time
Remuneration : enter 2.650€ to 3.770€ brut/gross monthly
Desired level of education : 5-year university degree
Experience required : Indifferent
Any structure submerged in a coastal zone undergoes the efforts related to sea currents and waves. Quantifying these efforts is a major challenge for the marine renewable energy sector. Under certain conditions, the deformations of the free surface around the structure are large enough that it breaks and generates the inclusion of air bubbles in the wake. These air entrainment phenomena impact the stresses on the structure. The objective of this project is to characterize these phenomena of inclusion of air downstream of the structure, in particular their conditions of appearance and their impact on the forces undergone by the structure under the combined effect of the swell and current. In this context, the researcher will conduct two-phase numerical simulations with the YALES2 code. The confrontation of the experimental and numerical results will allow a better understanding of the phenomena which affect the efforts on the partially immersed structures.
The researcher will have to conduct a large number of two-phase unsteady simulations with free surface with the platform YALES2. This platform is based on a sharp interface approach with interface tracking via a conservative level set method. In this approach, the pressure jump created by the surface tension is imposed via the ghost fluid method. The spatial integration is of the finite-volume type with 4-th order central numerical schemes. The YALES2 code features efficient dynamic and parallel mesh adaptation algorithms in order to achieve a high resolution at the interface. The researcher will have to reproduce the same operating points that will be measured in the wave channel. Particular attention will be paid to the treatment of boundary conditions to faithfully reproduce the swell seen by the immersed structure.
The second main activity will compare the experimental and numerical results: drag coefficient value, depth of the cavity downstream of the immersed cylinder, evaluation of the morphology and size of gaseous inclusions and their dynamics by phase average. For this, it will be necessary to have regular exchanges and to visit the partner laboratory (LOMC in Le Havre).
The required qualification includes a PhD in Physics or Applied Mathematics, solid knowledge in Numerical Fluid Mechanics, fluency in the use of numerical methods (finite volumes), the habit of programming in FORTRAN, the ability to work interactively in teams and with other teams, good knowledge of English (spoken, written).
For many years, the CORIA laboratory has been developing high-fidelity modeling approaches for two-phase turbulent flows. These nationally and internationally recognized approaches in the field of combustion are now used and developed for renewable energies in several projects such as RIN SEMARIN and M2SINUM, or ANR DYNEOL in which one seeks among others to model the wake of offshore wind turbines. The development of these methods is carried out with academic partners (SUCCESS Scientific Interest Group) and industrial partners (SAFRAN, ARIANE GROUP, SIEMENS / GAMESA).
Constraints and risks
During the project, the selected person will have to go regularly to the LOMC laboratory in Le Havre.
Closing date for the receipt of applications 1st Septembre 2019
 Ageorges, V., Peixinho, J., & Perret, G., Flow and air-entrainment around partially submerged vertical cylinders, Bulletin of the American Physical Society, 2018
 G. Pinon, G. Perret, L. Cao, A. Poupardin, J. Brossard, E. Rivoalen, “Vortex kinematics around a submerged plate under water waves. Part II: Numerical Computations”, European Journal of Mechanics – B/Fluids (65), pp. 368-383 (2017).
 A. Poupardin, G. Perret, G. Pinon, N. Bourneton, E. Rivoalen, J. Brossard, Vortex kinematic around a submerged plate under water waves. Part I: Experimental analysis, European Journal of Mechanics – B/Fluids, 34, 2012.
 YALES2 web site, http://www.coria-cfd.fr
 V. Moureau, P. Domingo & L. Vervisch, Design of a massively parallel CFD code for complex geometries. Comptes Rendus Mécanique (2011) 339 (2-3), 141–148.
Duration 1 year renewable 1 year
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