Seminar on Challenges in hydrogen combustion subgrid modeling by Prof. Temistocle Grenga on May 22nd 2025 at 12.00am room 0.2

Challenges in hydrogen combustion subgrid modeling
Prof. Temistocle Grenga
Department of Aeronautics and Astronautics - Faculty of Engineering and Physical Sciences
University of Southampton
Seminar at 12:00 - 22nd May 2025 Room 0.21

Lean premixed hydrogen flames exhibit unconventional characteristics when compared to
traditional hydrocarbon fuels, posing new challenges for the community and necessitating a deeper
understanding for the development of high-fidelity reduced-order models. A key aspect of hydrogen
combustion is its pronounced differential and preferential diffusion effects, quantified by the Lewis
number. While all flames exhibit hydrodynamic (or Darrieus-Landau) instabilities arising from the
abrupt density change across the flame front, lean hydrogen flames also display thermodiffusive
instabilities that arise from the low Lewis number of the fuel. These instabilities wrinkle the flame
front with the formation and destruction of cellular-like structures, thereby altering the flame
consumption speed and other flame characteristics.
Developing reduced-order models or manifold representations that can include both the chemical
effect and thermo-diffusive behaviour of these flames is of paramount importance for the
development of next-generation hydrogen-based combustion technologies.
Over the years, the community has focused on developing several formulations for reduced-order
models based on the flamelet hypothesis incorporating the thermo-diffusive effects in the
manifolds. The seminar will focus on a recently proposed Flamelet-Generated Manifold method
which includes a mixture-averaged diffusion transport model to account for the contributions of all
cross terms, as well as on recent progress in data-driven modeling

Prof. Temistocle Grenga is a Lecturer in Computational Fluid Dynamics for Aerospace at the University of Southampton
since February 2023. He is an expert in numerical simulation of turbulent reacting flows and data-driven modeling. He received a M.Sc. in Aeronautical Engineering at the Sapienza University of Rome (Italy) in 2009, a M.Sc. in Mechanical Engineering at the University of Notre Dame (USA) in 2013, and a Ph.D. in Aerospace and Mechanical Engineering at the same University in 2015. He was a Postdoctoral Research Associate at Princeton University (USA) from 2015 to 2018, and at RWTH Aachen (Germany) from 2018 to 2023, where he was also the Leader of the Multiphase Group and the HPC Group. He published more than 100 papers in international journals and conference proceedings. He supervised several PhD students investigating Machine Learning modeling of turbulent flows, conservative numerical methods for interface tracking, HPC GPU-based library for chemistry in CFD, and reduced order modeling of multiphase flows. He was invited as a lecturer on Machine Learning applications for fluid dynamics and combustion in several European schools for Ph.D. students (PRACE Advanced Training Center, ERCOFTAC, South-East Europe Combustion Spring School 2022, Combustion Autumn School 2022)