Adjust Font Size: Normal Large X-Large

Return to Events List


AEM Seminar: Molecular Scale Mass and Momentum Transport in Aerosols

Chris Hogan, Associate Professor and Director of Graduate Studies, Mechanical Engineering, University of Minnesota

2:30 PM on 2018-01-26

Akerman 319


The formation growth, and transport of nanometer scales particles/clusters in the gas phase (i.e. in aerosols) is of fundamental importance in a large number of naturally occurring and engineered phenomena, including but not limited to ambient air, forest fires, engine exhaust, as well as high temperature and plasma materials synthesis systems. While continuum transport equations can largely be used to describe changes in nanoparticle size distributions both patially and temporally (due to convective/diffusive transport, and reactions driving growth), particle transport rates (diffusion coefficient/mobility) and growth rates (rate of molecular condensation) are directly dependent on molecular scale interactions. Specifically, nanoparticle transport and growth are dependent upon mass and momentum accommodation coefficients for gas molecules and reactive vapor species colliding with particles. This presentation will review recent progress by our group in making measurements of momentum accommodation on nanometer scale, controlled chemical composition clusters in the gas phase, in developing computational approaches to predict drag and diffusion coefficients for clusters based upon prescribed gas molecule impingement-reemission rules, and in experimentally and numerically examining the condensational growth of nanometer scale clusters. In general, our results show that the classical assumptions of complete momentum accommodation and complete mass accommodation are not appropriate for particles at the nanometer scale, and in many instances momentum and mass accommodation are strongly chemistry dependent.

Biography: Chris Hogan is an associate professor and the director of graduate studies in the department of mechanical engineering at the University of Minnesota. His research focuses on transport phenomena in aerosols, the design of gas phase measurement instruments, and the application of aerosol technology in additive manufacturing. He received his undergraduate degree from Cornell University, his PhD from Washington University in Saint Louis, and was a

Postdoctoral Associate at Yale University before joining the University of Minnesota faculty in 2009. He is the recipient of the Sheldon K. Friedlander Award in 2011 from the American Association for Aerosol Research, the 2013 Smoluchowski Award from the German Aerosol Research Society, and was a 2010 Japan Society for the promotion of science visiting faculty fellow.

More information about his research can be found at his website: https://chrishogansite.wordpress.com/


Return to Events List