10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Mobility of Nanofiber, Nanorod and Non-spherical Nano-agglomerates in Gases
LIN TIAN, Goodarz Ahmadi, Jiyuan Tu, RMIT University
Abstract Number: 1716 Working Group: Aerosol Physics
Abstract Accurate measurement and classification of nanoparticles are in great need in context of fast development of nanotechnology. Nanoparticles frequently appear in non-spherical forms such as long aspect ratio nanofibers, nanotubes, and irregular nano-agglomerates. While well-developed classical studies were mainly in continuum regime with spherical particles, dynamics of non-spherical nanoparticles is still not fully understood. In this study, orientation averaged mobility of the nanofiber and nanorod is examined by methods of Brownian diffusion theory, a combination of the collision limited reaction rate theory and the bipolar diffusion charging analysis, and empirical predications from measurements. The study leads to the discovery of a surface dominated mobility for nanoparticles with Knudsen number greater than 5 (Kn > 5). In view of the extreme relative length scales between particle size and gas mean free path, particles of all morphologies can be viewed as point collision and therefore the equivalent surface mobility diameter is reasonably justified. As expected, the accuracy of this approximation reduces as the Knudsen number decreases. When Kn < 0.1, the study shows that the particle morphology starts to play an important role.