10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Fractal Scaling of Soot Packing density Across Five Size Decades
PAI LIU, William Heinson, Rajan K. Chakrabarty, Washington University in St. Louis
Abstract Number: 844 Working Group: Aerosol Physics
Abstract Fractal aggregates in nature grow with a scaling dimensionality less than the spatial dimension. This results in their packing density (θf)–defined as the fraction of volume occupied by solid component–decreasing with increasing size Rg/a (aggregate radius of gyration normalized by average monomer radius). Fundamental questions remain regarding the scaling laws and physical mechanisms controlling the evolution of θf for the aggregates produced from combustion systems, especially after the onset of gelation. Here, we experimentally map the scaling of θf for soot aggregates across five orders of magnitude of Rg/a. The θf-Rg/a scaling relationship evolves through three successive regimes with distinct power-law exponents of -1.20±0.01, -0.58±0.06, and -1.31±0.14. The first cross-over agrees with the classical aerosol-to-gel transition theory. This agreement, however, breaks down at the second cross-over point, where a late-stage cluster-cluster aggregation of gel particles takes over.