Amit Chakrabarti

amit Superaggregates in Cluster-dense Soot Aggregation

About the Presenter:

Amit Chakrabarti is currently the William and Joan Porter Professor and Head of Physics at Kansas State University. Chakrabarti received his PhD in Physics from University of Minnesota in 1987. After post-doctoral work at Temple and Lehigh Universities, Chakrabarti joined Kansas State in 1990 as an Assistant Professor. Chakrabarti is a soft matter physicist and has published over 150 peer reviewed articles. His current research interests are self-assembly of aerosols, colloids, nanoparticles, and proteins, and modeling light scattering from irregularly shaped particles. He has received Kansas State University’s Commerce Bank Distinguished Graduate Faculty Award (2009) and Presidential Award for Excellence in Undergraduate Teaching (2002).

Full Presentation:

Abstract:

The concept of superaggregates in cluster-dense diffusion limited cluster-cluster aggregation (DLCA) was first developed at Kansas State University laboratories. From both large-scale computer simulations and experimental studies of heavily sooting flames, we have shown that soot aggregates in the cluster-dense regime have a hybrid morphology with a “traditional” fractal dimension of 1.8 at smaller length scales and a percolation fractal dimension of 2.5 at larger length scales. We have also characterized the crossover length scale in terms of an ideal gel point description. Subsequently, such hybrid soot morphology and a larger fractal dimension of 2.5 were observed in various other experimental studies. In the current work, we will address the percolation analogy for superaggregates in details both from the point of view of fractal dimension and shape of the clusters. Our work will focus on a scaling description of the DLCA clusters at the ideal gel point and the shape anisotropy of the clusters. A detailed comparison with static percolation clusters will be presented as well. We will also address the implication of hybrid morphology of DLCA clusters on the scattering properties of soot aerosols.