2021-04111 - Post-Doctoral Research Visit F/M h-adaptation strategies and unified basis representation for surrogate and reduced order modelling of fluid flows with immersed/embedded parametrized geometries

Contract type : Fixed-term contract

Renewable contract : Oui

Level of qualifications required : PhD or equivalent

Fonction : Post-Doctoral Research Visit

Level of experience : Recently graduated

About the research centre or Inria department

The Inria Bordeaux Sud-Ouest centre is one of Inria's eight centres and has around twenty research teams. The Inria centre is a major and recognized player in the field of digital sciences. It is at the heart of a rich R&D and innovation ecosystem: highly innovative SMEs, large industrial groups, competitiveness clusters, research and higher education players, laboratories of excellence, technological research institute...

Context

Within the framework of the European project EuroHPC-02-2019  eflows4HPC, and in collaboration with the partners of the pillar I of the project: CIMNE, SISSA, SIEMENS and Duke University.

With hosting by the Inria  Bordeaux Sud-Ouest research center and regular travel foreseen within the activities and collaborations mentioned above.

Developments contributing to the open source projects mmg and kratos multiphysics, as well as  the model reduction libraries RBniCS and the ITHACA suite by Sissa, and some in house research codes for  some of the initial methodological developments. Where possible workflows environments developed at the Barcelona Supercoputing Center (coordinator of  eflows4HPC, see for example comps) will be used to allow an efficient and transparent management of data, computational ressources, and processes.

Assignment

Assignments :
The main objetive of this work is to develop improved adaptive remeshing techniques in the framework of model reduction and optimization with parametrized geometries, and in particular in conjunction with immersed and/or embedded boundary simulations. The purpose is twofold:

  • on one side to propose an efficient (in terms of storage) and unified spatial basis setting to represent multiple solutions on unstructured adaptive meshes. This requirement is essential to provide an efficient unified representation of multiple solutions on adaptive meshes in a parametrized setting. This representation is necessary for several operations related to inverse modelling, of model reduction (e.g. method of snapshots), to compute statistics etc.
  • on the other hand we aim at exploiting the information available in a parametrized setting to speed up the adaptation process itself by e.g. constructing appropriate surrogate models of mesh metrics or error estimators

These assignements will both involve theoretical work related to  error estimation and approximation in physical and parametric space, with a final demonstration in an efficient setting involving workflows developed at the Barcelona Supercomputing center and based on open source software developed at Inria, Cimne, and at Sissa.

For a better knowledge of the proposed research subject :

N. Barral, G. Olivier and F. Alauzet, Time-accurate anisotropic mesh adaptation for three-dimensional time-dependent problems with body-fitted moving geometries, Journal of Computational Physics, 2017

Baiges, J, Codina, R, Castañar, I, Castillo, E. A finite element reduced-order model based on adaptive mesh refinement and artificial neural networks. Int J Numer Methods Eng. 2020; 121: 588– 601.

Barros, G.F., Grave, M., Viguerie, A. et al. Dynamic mode decomposition in adaptive mesh refinement and coarsening simulations. Engineering with Computers (2021). https://doi.org/10.1007/s00366-021-01485-6

M. Balajewicz and C. Farhat, Reduction of nonlinear embedded boundary models for problems with evolving interfaces, Journal of Computational Physics 274, 2014 : 489-504, 

Collaboration :

The recruited person will be working with several members of the team, and in particular N. Barral, H. Beaugendre and M. Ricchiuto. Interactions with local experts in model reduction (e.g. T. Taddei, Memphis team) are envisioned. Strong interactions with the partners of the pillar I of the  eflows4HPC European project  (CIMNE, SISSA, SIEMENS and Duke University) are foreseen.

Main activities

 Main activities :

- adaptation strategies for multiple solutions: one way coupling using metric intersections

- development of new coupling strategies based on space-time-parametric space error estimators

- smart surrogate error modelling for mesh adaptation speed up

- applications to academic benchmarks

- evaluation on realistic heat transfer/fluid flow applications using the coupling kratos multiphysics-mmg-ithaca (or RBniCS)

Additional activities :

- publications (journal articles, conference presentations)

- participation to official meetings and (partly) management within the eflows4HPC project

- (co-) supervision (master students and perhaps of a R&R engineer)

Skills

Technical skills and level required :

Proficient in numerical methods for fluids on unstructured grids. Knowledge in approximation theory, error estimation, and mesh generation/adaptation

will be greatly appreciated. Some basic knowledge of surrogate modelling and/or model reduction method will be also evaluated favourably.

Proficiency in object oriented programming, and some basic understanding of his performance computing techniques is required.

Languages : Proficiency in English  is a must

Relational skills : ready to work in a truly international environnement, within a multicultural team, and to interact

with collaborators from different horizons (applied math, engineering, computer science).

 

 

 

Benefits package

  • Subsidized meals
  • Partial reimbursement of public transport costs
  • Leave: 7 weeks of annual leave + 10 extra days off due to RTT (statutory reduction in working hours) + possibility of exceptional leave (sick children, moving home, etc.)
  • Possibility of teleworking (after 6 months of employment) and flexible organization of working hours
  • Professional equipment available (videoconferencing, loan of computer equipment, etc.)
  • Social, cultural and sports events and activities
  • Access to vocational training
  • Social security coverage

Remuneration

the gross monthly salary will be 2653 euros (before social charges on salary and monthly withholding taxes for income)