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Job Record #17958
TitleNumerical simulations of boiling phenomena : impact on material
CategoryPostDoc Position
EmployerCEA Saclay, Direction of Energies, Simulation in Fluid Mechanic
LocationFrance, Paris - Saclay
InternationalYes, international applications are welcome
Closure Date* None *
Description:
Corrosion phenomena result in significant costs amounting to around 3 to 4% of the GDP of OECD countries. They may take multiple forms depending on the conditions in which they appear. A poorly studied case with yet strong industrial interest is the corrosion of a material in contact with a corrosive boiling fluid. Indeed, boiling generates peculiar conditions with respect to corrosion. On one hand, part of the surface is periodically in contact with either the liquid or the vapour phase; on the other hand, local thermal conditions (heat flux and wall temperature) strongly depend on time and on the position with respect to the triple contact line (i.e., whether it is inside or outside of the bubble). It is currently very difficult to characterise experimentally such rapid and small variations; hence, Direct Numerical Simulations (DNS) are then a relevant tool to study the fine scales involved in the process and so doing, to study the phases of an ebullition cycle (rapid inertial growth, thermally controlled growth, detachment and waiting time). The post-doc’s objective is to simulate the boiling process at the scale of a single bubble using appropriate numerical approach. The intent is to describe finely the thermal conditions and their time evolution on an idealised boiling cycle, in order to deduce their consequences on the material’s corrosion. With the Front-Tracking method implemented in TRUST/TrioCFD [1] OpenSource code, one can follow the time evolution of a liquid/vapour interface in contact with a heating wall. Mass conservation is ensured by coupling with a Volume Of Fluid (VoF) approach, while heat transfer is accurately captured at the interface by the ghost-fluid approach inspired by the Level-Set method. This hybrid method was recently coupled with a subgrid model to consider the smallest scales in the contact line neighbourhood and in particular, their effects on the apparent contact angle and on the heat flux, singularly large in this region [2]. First elements of validation on 2D axisymmetric cases are encouraging. Now, further work is required to couple this model with the resolution of heat conduction in the solid and to extend it to 3D configurations. The effect of the moving triple contact line can also be considered. Then, the coupled model will be used to simulate the bubble growth on a single nucleation site to compare the results with recent experimental data produced at STMF/LIEFT [3]. Finally, a simulation adapted to the conditions of the experiment CONSTANSE UP lead at SCCME/LECNA will be simulated. A characteristic wall temperature evolution will be extracted from this simulation to assess the effects of contact line motion. The candidate will then work with corrosion’s experts to process numerical data (relevant averages, …) in order to prepare their use in corrosion’s models and the comparison to experimental observations of corrosion. Skills / expertise PhD in computing / artificial intelligence / numerical methods and tools / fluid mechanics with (if possible) previous experience in corrosion or in two-phase fluid mechanics. Références [1] TrioCFD website : https://triocfd.cea.fr/ [2] V. Janecek, Evaporation at microscopic scale and at high heat flux, PhD thesis, 2012. [3] C. Tecchio, Experimental study of boiling: characterization of near-wall phenomena and bubble dynamics, PhD thesis, 2022.
Contact Information:
Please mention the CFD Jobs Database, record #17958 when responding to this ad.
NameBOIS Guillaume
Emailguillaume.bois@cea.fr
Email ApplicationYes
URLhttps://www-llb.cea.fr/Pisp/vadim.nikolayev/index.php?id=254
Record Data:
Last Modified19:19:52, Thursday, August 11, 2022

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