Wed, Mar 02, 2022 @ 03:30 PM - 04:30 PM
Aerospace and Mechanical Engineering
Conferences, Lectures, & Seminars
Speaker: Michael Burke, Columbia University
Talk Title: Non-Equilibrium Behavior in Combustion, Planetary Atmospheres, and Compressible Flows
Abstract: Chemically reacting flows are often interpreted and computed under the premise that all chemical species have a range of energies in their rotational and vibrational modes that are well described by the Boltzmann or thermal distribution at the local temperature. Of course, breakdown in this premise can occur naturally as a result of chemical reactions, light absorption, and/or shock waves. The manifestations of this breakdown on unimolecular reactions, where non-thermally distributed molecular ensembles dissociate, are well known to give rise to pressure-dependent reactions in combustion, photochemical reactions in the Earth atmosphere, and induction time lags in reactions following shock waves. By contrast, manifestations of non-equilibrium behavior on bimolecular reactions, where non-thermally distributed molecules react with other species, are generally less understood and historically less appreciated. Here, I describe three distinct tales of such non-equilibrium behavior across varied application domains. In particular, I present results from ab initio master equation calculations that shed light on previous hypotheses and experimental observations and reveal new processes involving non-equilibrium induced by chemistry in combustion, photons in the Earth atmosphere, and shock waves in compressible flows. Namely, the rovibrationally excited ephemeral complexes, formed from association of two molecules, with a third molecule give rise to a fourth, long-forgotten type of phenomenological reaction, involving three chemical reactants, that impacts macroscopic combustion behavior; the vibrationally excited complexes, formed upon photon absorption, collide with oxygen to produce radicals even for low photon energies in the Earth troposphere; and the rovibrationally cold molecular ensembles encountered following shock waves not only slow the reaction timescales but also change the main chemical pathways.
Biography: Michael Burke is an Associate Professor of Mechanical Engineering at Columbia University, where he also holds affiliate appointments in Chemical Engineering and the Data Science Institute. Prior to joining Columbia in 2014, Burke earned his Ph.D. in Mechanical and Aerospace Engineering in 2011 at Princeton University, where he was a Wallace Memorial Honorific Fellow, and he worked as a Directors Postdoctoral Fellow in the Chemical Sciences and Engineering Division at Argonne National Laboratory. Burke is a recipient of the National Science Foundations CAREER award, the Combustion Institutes Research Excellence Award, the Combustion Institutes Hiroshi Tsuji Early Career Researcher Award, and the American Chemical Societys PRF Doctoral New Investigator Award. His publications have been featured in the News and Views section of Nature Chemistry, selected as the Feature Article in Combustion and Flame, and chosen for the Distinguished Paper Award at the 31st International Symposium on Combustion. His research combines physics and data across multiple scales to unravel and predict outcomes of complex reacting systems in varied application domains with major emphases on theoretical chemistry of nonequilibrium processes, multiscale datadriven modeling, and highthroughput experiments selected by optimal design.
Host: AME Department
More Info: https://usc.zoom.us/j/93987337017?pwd=MWd2dXBSL1FaR1RPaHNscjJ1NW80UT09
Audiences: Everyone Is Invited
Contact: Tessa Yao