Diffusion in Ordered and Disordered Media
PURDUE UNIV LAFAYETTE IN DEPT OF PHYSICS
Pagination or Media Count:
In this project, we have investigated the Brownian motion taking place in ordered and disordered media using various complementary approaches. These include the analysis of the eigenvalues and eigenvectors of the transition probability matrix which represents both the media geometry and the kinetics of Brownian motion. This matrix is typically a large, random, Markov, matrix and is shown to possess eigenspectrum with scaling properties which has been analyzed numerically. Secondly, the same matrix has been used to evaluate autocorrelation functions directly and exactly taking advantage of high speed vector computation. Thirdly, the Langevin approach to diffusion has been extended to incorporate the anomalous diffusion on fractal media. Lastly, the frequency dependent conductivity of inhomogeneous media has been investigated using a persistent random walk model and the aforementioned numerical technique of the calculation of step autocorrelation functions. This last work has already revealed the unexpected effects of the interplay between the mean free path of the diffusing particle carrier, the carrier density, and the length scale of inhomogeneity, in the media. This work represents what we believe to be the coherent efforts to understand the diffusion and transport in disordered media.
- Nuclear Physics and Elementary Particle Physics