Numerical simulation of reacting flows with a detailed chemistry remains a formidable challenge in practical combustion devices. Two main strategies have been proposed to overcome the challenge: chemical reduction techniques and flamelet-based reduced-order models. The focus of this talk is the latter methods since they have notable advantages not only in reducing computational cost but also in modeling turbulence-chemistry interaction. The classical one-dimensional (1D) flamelet equations are derived based on an assumption: flame-normal transport of thermochemical state variables in mixture fraction gradient direction dominates over tangential transport (TD) along iso-surfaces of mixture fraction. Recently, we have performed a multi-scale asymptotic analysis to assess the relevance of TD effects in the generalized 3D flamelet equations. A regime diagram is developed and three different flamelet (classical 1D flamelet, curved 1D flamelet, and 3D flamelet) regimes are identified. Furthermore, a novel on-the-fly tracking approach is used to quantify the contribution of TD in a temporally evolving turbulent syngas jet flame. It is found that TD effects may play an important role in the regions with large curvature and finite-rate chemistry. Moreover, the most probable cause and effect chain that elucidates the source of TD is proposed for the first time from a flow topology perspective. More recently, TD is also used as an important performance indicator to assess tabulation strategies, differential diffusion effects, and Soret effects in turbulent non-premixed combustion.
Jointly trained at The University of Michigan and Peking University, Dr. Wang Han obtained his Ph.D. degree in Fluid Mechanics in 2017. Prior to joining the University of Edinburgh as Lecturer in Computational Reactive Flows in 2020, he was a Postdoctoral Research Associate (2017-2019) in the STFS institute at TU Darmstadt Germany, Visiting Research Associate (2019) at CRF-Sandia National Labs, and Research Associate (2019-2020) at UNSW Sydney Australia.
Dr. Han won the prestigious German DAAD Fellowship in 2017 and Bernard Lewis Fellowship from the Combustion Institute in 2018. Currently, he is PI for the UKRI-funded Pioneer Project. At the University of Edinburgh, he is building the Laboratory for Simulation of Multiphase and Reactive Thermofluids (SmartLab) that interacts closely with Prof. Mark Linne, Dr. Brian Peterson and Dr. Antonio Attili. In the SmartLab, high performance computational fluid dynamics models, Machine Learning methods, and 3D Printing technologies are leveraged to explore multiphase and reactive thermofluids that underpin the performance of propulsion & power systems and the dynamics of accidental fires.
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