par Boon, Jean-Pierre 
;Lutsko, James
Référence Journal of statistical physics, 166, 6, page (1441-1454)
Publication Publié, 2017-03
;Lutsko, James Référence Journal of statistical physics, 166, 6, page (1441-1454)
Publication Publié, 2017-03
Article révisé par les pairs
| Résumé : | The temporal Fokker–Planck equation (Boon et al. in J Stat Phys 3/4: 527, 2003) or propagation–dispersion equation was derived to describe diffusive processes with temporal dispersion rather than spatial dispersion as in classical diffusion. We present two generalizations of the temporal Fokker–Planck equation for the first passage distribution function fj(r, t) of a particle moving on a substrate with time delays τj. Both generalizations follow from the first visit recurrence relation. In the first case, the time delays depend on the local concentration, that is the time delay probability Pj is a functional of the particle distribution function and we show that when the functional dependence is of the power law type, Pj∝fjν-1, the generalized Fokker–Planck equation exhibits a structure similar to that of the nonlinear spatial diffusion equation where the roles of space and time are reversed. In the second case, we consider the situation where the time delays are distributed according to a power law, Pj∝τj-1-α (with 0 < α< 2), in which case we obtain a fractional propagation-dispersion equation which is the temporal analog of the fractional spatial diffusion equation (with space and time interchanged). The analysis shows how certain microscopic mechanisms can lead to non-Gaussian distributions and non-classical scaling exponents. |
