Aerogelation Process Simulation by a Cluster-Cluster Aggregation Algorithm

A ballistically-limited cluster-cluster aggregation (BLCA) model was developed to simulate aerogelation processes. In the model, the clusters move along linear paths, in random directions, in a finite box. When two aggregates contact each other, they are combined irreversibly to form a larger aggreg...

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Bibliographic Details
Published in:Journal of sol-gel science and technology 1999-08, Vol.15 (2), p.137-146
Main Author: Hasmy, Anwar
Format: Article
Language:English
Subjects:
Agglomeration
Aggregates
Algorithms
Clusters
Computer simulation
Fourier transforms
Fractal geometry
Fractals
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Summary:A ballistically-limited cluster-cluster aggregation (BLCA) model was developed to simulate aerogelation processes. In the model, the clusters move along linear paths, in random directions, in a finite box. When two aggregates contact each other, they are combined irreversibly to form a larger aggregate. As expected, the simulations show that the aggregation time is much shorter than that obtained with diffusion-limited cluster-cluster aggregation (DLCA) models. The minimum concentration, cg, required for gel formation scales as LD−3, where L is the length of the sides of the box and D is the fractal dimension of the aggregates (D ≈ 1.95). For a concentration c larger than cg, the mean free path of the aggregating clusters, 〈λ〉, scales as c−1.1. The pair correlation function g(r) and its Fourier transform S(q) were determined for the single large aggregates formed at the end of the simulations. These functions indicate that there is a characteristic length ξ which scales as c1/(D−3). As observed previously for the DLCA model, there is a discrepancy between the fractal dimensions obtained from g(r) and S(q).
ISSN:0928-0707
1573-4846
DOI:10.1023/A:1008787421829