10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Brownian Diffusion of Nano-Fibers
LIN TIAN, Goodarz Ahmadi, Jiyuan Tu, RMIT University
Abstract Number: 1714 Working Group: Aerosol Modeling
Abstract Motion of nanoparticles that are suspended in fluids are dominated by Brownian diffusion – a physical property well understood following Einstein (1905). While theoretical derivation and experimental measurement of the diffusion coefficients for spherical particles are well developed, such information for non-spherical particles are lacking. In this study, the Brownian diffusion of elongated nano-fibers is investigated numerically. Motion of the nano-fiber is resolved by solving the system of equations governing its coupled translational and rotational motion. To isolate the Brownian diffusion from other diffusive forces, test fibers are immersed in an unbounded quiescent fluid where only the hydrodynamic drag and Brownian forces are present. The study allows a close look at the Brownian diffusion of the nano-fibers with respect to the translation, rotation, coupling, and how the rotation affects the particle’s macroscopic diffusion properties. Particular attention was given to the rotational relaxation time in determining the non-spherical particle’s isotropic and anisotropic diffusive properties. Theoretical and semi-empirical equations are developed to quantify the diffusion coefficients of nano-fibers. The predications are compared with the experimental data, and excellent agreement was obtained. The study opens up new approaches for studying fundamental diffusive processes of nano-particles of complex shapes which are abundant in natural environment.