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Job Record #17717
TitleSimulations of hydrogen deflagrations using LES and AMR
CategoryPhD Studentship
LocationFrance, Rueil-Malmaison
InternationalYes, international applications are welcome
Closure DateFriday, July 01, 2022

A significant reduction of greenhouse gases emissions is needed to keep global 
warming at an acceptable level in the next decades. In particular, the 
decarbonization of the energy and transport sectors is necessary to meet the 
objectives. The use of hydrogen is a plausible alternative to fossil fuels as 
its consumption, through traditional combustion processes or in fuel cells, is 
carbon-free. It may for instance provide flexibility to systems based on wind 
and solar energies. However, hydrogen is a volatile and highly flammable 
compound. Its storage and use are associated with high risks of explosions which 
must be adequately addressed. As experiments concerning hydrogen deflagrations 
are difficult and expensive to set-up, it is often interesting to use numerical 
tools to assess the hazard related to an industrial hydrogen installation. These 
numerical models must be able to predict the propagation of a flame in an 
environment which is either inherently turbulent, or where turbulence is 
generated by the interactions between the flame and obstacles.
Scientific challenge

The simulation of turbulent flows requires the resolution of a wide range of 
physical scales, from the smallest scales called Kolmogorov scales to the 
largest scales called integral scales. Adequate simulation techniques, in 
particular Large Eddy Simulation (LES), enable the numerical resolution of 
industrial systems by modeling all or part of the turbulent scales. 
Nevertheless, many issues remain to be overcome, especially in the case of 
large-scale and highly unsteady systems, as is the case for explosions in 
industrial environments. Indeed, the definition of numerical meshes fine enough 
to solve the turbulent structures leads to computation times that are currently 
out of reach. The turbulence is often generated by the flame, which propagates 
rapidly in the domain. One solution consists in using the Adaptive Mesh 
Refinement (AMR) technique, which allows to dynamically refine the mesh during 
the calculation. This gives rise to a good use of the available resources and 
the possibility to simulate large domains. Nevertheless, the use of AMR requires 
the definition of an efficient activation criterion. Despite attempts made by 
various teams, the definition of a universal AMR sensor based on physical 
quantities related to turbulence is an open problem. 
Thesis objectives

The objective of this thesis is to propose an efficient AMR sensor to solve 
turbulence in the LES of large-scale systems. The research strategy will involve 
the following steps:
i)	Proposition of one or more AMR sensors, based on the literature and 
original ideas
ii)	Test of the retained strategies on academic cases of increasing 
iii)	Validation of the retained model on an industrial case of interest, in 
the field of hydrogen industrial security.

Academic supervisor: Pr Pierre SAGAUT, M2P2 laboratory (Aix-Marseille 

Academic requirements: University Master degree involving CFD, physics and/or 
numerical modelling

Contact Information:
Please mention the CFD Jobs Database, record #17717 when responding to this ad.
NameC├ędric Mehl
Email ApplicationYes
Address1-4 av. Du Bois Preau
Record Data:
Last Modified09:58:52, Monday, April 04, 2022

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