Breakdown of Dynamical Scale Invariance in the Coarsening of Fractal Clusters

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We extend a previous analysis [PRL {\bf 80}, 4693 (1998)] of breakdown of dynamical scale invariance in the coarsening of two-dimensional DLAs (diffusion-limited aggregates) as described by the Cahn-Hilliard equation. Existence of a second dynamical length scale, predicted earlier, is established. Having measured the "solute mass" outside the cluster versus time, we obtain a third dynamical exponent. An auxiliary problem of the dynamics of a slender bar (that acquires a dumbbell shape) is considered. A simple scenario of coarsening of fractal clusters with branching structure is suggested that employs the dumbbell dynamics results. This scenario involves two dynamical length scales: the characteristic width and length of the cluster branches. The predicted dynamical exponents depend on the (presumably invariant) fractal dimension of the cluster skeleton. In addition, a robust theoretical estimate for the third dynamical exponent is obtained. Exponents found numerically are in reasonable agreement with these predictions.
11 pages, 10 figures

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Disordered Systems and Neural Networks, Statistical Mechanics, Pattern Formation and Solitons

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http://salesiana.dossiersoluciones.com/handle/123456789/30109

Consulte el texto completo en el siguiente enlace:

https://arxiv.org/abs/cond-mat/9912426
 http://arxiv.org/abs/cond-mat/9912426

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arXiv