A computer simulation was presented for the treatment of 1-dimensional particle migration via local hopping of Chandrasekhar type. There was no local bias, but the hopping rates varied with position in the system. Of the 2 possible diffusion equations which could represent the process, one was clearly shown to be wrong while the other gave an accurate representation of the evolution of the system. The cases of both reflecting and absorbing boundaries were considered and, in the latter case, a sum-rule which had previously been derived for this type of random migration was confirmed. The concept of local particle traffic was introduced, and arguments were advanced in order to show that the spatial traffic distribution gave a better insight into some aspects of particle activity than did the probability distribution.

R.Collins, S.R.Carson, J.A.D.Matthew: American Journal of Physics, 1997, 65[3], 230-7