The seventy-sixth UQSay seminar on UQ, DACE and related topics will take place online on Thursday afternoon, October 17, 2024.
4–5 PM — Habib Najm (Sandia National Laboratories)
Uncertainty Quantification in Computational Combustion Models
Uncertainty quantification (UQ) in large scale computational combustion models faces key challenges of high dimensionality and computational cost. These models, particularly when using detailed chemical mechanisms, typically involve large numbers of uncertain parameters. Exploring these high-dimensional spaces necessitates the use of large numbers of computational samples, which, given high computational costs, is prohibitively expensive. I will discuss a UQ workflow, and underlying methods, to address this challenge in practice. These methods include global sensitivity analysis with polynomial chaos (PC) sparse regression, coupled with multilevel multifidelity methods. The combination of these tools is often useful to reliably cut-down dimensionality with acceptable computational costs, identifying a lower-dimensional subspace where the construction of PC surrogates of requisite accuracy is feasible. These surrogates are in turn necessary for both Bayesian inference and forward uncertainty propagation purposes. I will discuss this UQ workflow for problems of practical relevance in combustion. I will also touch on the issue of data availability, and the challenge of Bayesian estimation of uncertain model parameters given sparse or missing data.
Organizing committee: Pierre Barbillon (MIA-Paris), Julien Bect (L2S), Nicolas Bousquet (EDF R&D), Vincent Chabridon (EDF R&D), Amélie Fau (LMPS), Filippo Gatti (LMPS), Clément Gauchy (CEA), Bertrand Iooss (EDF R&D), Alexandre Janon (LMO), Sidonie Lefebvre (ONERA), Didier Lucor (LISN), Sébastien Petit (LNE), Emmanuel Vazquez (L2S), Xujia Zhu (L2S).
Coordinators: Sidonie Lefebvre (ONERA) & Xujia Zhu (L2S)
Practical details: the seminar will be held online using Microsoft Teams.
If you want to attend this seminar (or any of the forthcoming online UQSay seminars), and if you do not already have access to the UQSay group on Teams, simply send an email and you will be invited. Please specify which email address the invitation must be sent to (this has to be the address associated with your Teams account).
You will find the link to the seminar on the "General" UQSay channel on Teams, approximately 15 minutes before the beginning.
The technical side of things: you can use Teams either directly from your web browser or using the "fat client", which is available for most platforms (Windows, Linux, Mac, Android & iOS). We strongly recommend the latter option whenever possible. Please give it a try before the seminar to anticipate potential problems.
