Morphology and mobility of synthetic colloidal aggregates

Abstract

The relationship between geometric and dynamic properties of fractallike aggregates is studied in the continuum mass and momentum-transfer regimes. The synthetic aggregates were generated by a cluster-cluster aggregation algorithm. The analysis of their morphological features suggests that the fractal dimension is a descriptor of a cluster's large-scale structure, whereas the fractal prefactor is a local-structure indicator. For a constant fractal dimension, the prefactor becomes also an indicator of a cluster's shape

Friction Coefficient and Mobility Radius of Fractal-Like Aggregates in the Transition Regime

“…3) (Isella and Drossinos 2011) and then applied to fractal-like aggregates to determine their continuum-regime mobility radius (Melas et al 2014a). The validity of the CRM was extended to the slip-flow and transition regimes in Melas et al (2014b).…”

“…Moreover, these aggregates share many features with aggregates generated by physical process-based algorithms. A detailed description of the algorithm and the properties of the aggregates it generates can be found in a previous work (Melas et al 2014a).…”

“…The mobility of aerosol particles is a fundamental property as it determines their friction (Melas et al 2014a) and diffusion (Cai and Sorensen 1994) coefficients, and it influences particle coagulation (Kostoglou and Konstandopoulos 2001). Aerosol particles may form complex structures, the calculation of their dynamic properties becoming more demanding as their structure becomes more complex.…”

“…The mobility of these structures is usually expressed via the equivalent mobility radius, R m , the radius of a virtual sphere of the same average mobility (friction coefficient) as the aerosol particle of irregular shape under the same flow conditions (Filippov 2000). The main factors that influence the mobility radius are morphology (Melas et al 2014a) and the momentum-transfer regime, as specified by a characteristic particle length scale (Melas et al 2014b).…”

“…In Equation (5) N is the number of monomers, k L a prefactor which depends on the local aggregate structure (Melas et al 2014a) Melas et al (2014a). The scaling law can be rewritten for dynamic characteristic lengths like the mobility radius (Schmidt-Ott 1988),…”