Berkeley Fluids Seminar

University of California, Berkeley

Bring your lunch and enjoy learning about fluids!

Monday, April 2, 2018

12:00-13:00, 3110 Etcheverry Hall

Dr. Jacqueline H. Chen (Sandia National Laboratory)

Petascale Direct Numerical Simulation of Heterogeneous Spontaneous Ignition Relevant to Engines

Abstract: Due to the unrivaled energy density of liquid hydrocarbon fuels combustion will continue to provide over 80% of the world’s energy for at least the next fifty years. Hence, combustion needs to be understood and controlled to optimize combustion systems for efficiency to prevent further climate change, to reduce emissions and to ensure U.S. energy security and competitiveness. In this talk I will discuss progress in direct numerical simulations of turbulent combustion focused on providing fundamental insights into key ‘turbulence-chemistry’ interactions that underpin the development of next generation fuel efficient, fuel flexible engines for transportation and power generation. Petascale direct numerical simulation (DNS) of multi-stage mixed-mode turbulent combustion have elucidated key physics that govern autoignition and flame stabilization in engines and provide benchmark data for combustion model development under the conditions of next generation engines, which operate near combustion limits to maximize efficiency and to minimize emissions. Mixed-mode combustion refers to premixed or partially-premixed flames propagating into compositionally stratified (non)reacting/autoignitive mixtures. Multi-stage ignition refers to hydrocarbon fuels with negative temperature coefficient behavior that undergo sequential low- and high-temperature autoignition. Some of the issues addressed include the role of entrainment and mixing in turbulent shear flows on the dynamics of multi-stage ignition, and the balance of flame propagation versus spontaneous ignition in contributing to the overall combustion rate.

Bio: Jacqueline H. Chen is a Distinguished Member of Technical Staff at the Combustion Research Facility at Sandia National Laboratories. She has contributed broadly to research in petascale and exascale direct numerical simulations (DNS) of turbulent combustion focusing on fundamental turbulence-chemistry interactions underlying the design of fuel efficient clean burning engines. These benchmark simulations provide fundamental insight into combustion processes and are used by the combustion modeling community to develop and validate turbulent combustion models for engineering computational fluid dynamics. In collaboration with computer scientists and applied mathematicians she was the founding Director of the Center for Exascale Simulation of Combustion in Turbulence (ExaCT). She led an interdisciplinary multi-laboratory team to co-design DNS numerical algorithms, domain-specific programming environments, scientific data management and in situ uncertainty quantification and analytics, and architectural simulation and modeling with combustion proxy applications. She is also the principal investigator of a DOE Exascale Simulation Project focused on combustion simulation. She is a member of the National Academy of Engineering and a Fellow of the Combustion Institute. She received the DOE INCITE Award between 2005-2018 and the 34th International Combustion Symposium Distinguished Paper Award in 2012. She is a member of the DOE Advanced Scientific Computing Research advisory committee (ASCAC) and a member of the Combustion Institute board of directors. She was the editor of Flow, Turbulence and Combustion, the co-editor of the Proceedings of the Combustion Institute, volumes 29 and 30, and the Co-Chair of the Local Organizing Committee for the 35th International Combustion Symposium.

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