2006 International Conference in Honor of Jacqueline Fleckinger.
Electronic Journal of Differential Equations,
Conference 16 (2007), pp. 1-13. 

Title: Fractional flux and non-normal diffusion

Authors: Ali Abdennadher (Institut National des Sciences, Tunisie)
         Marie-Christine Neel (Univ. of Avignon, France)
 
Abstract: 
 Fractional diffusion equations are widely used for mass spreading in
 heterogeneous media. The correspondence between fractional equations and
 random walks  based upon stable Levy laws, keeps in analogy with that
 between heat equation and Brownian motion.
 Several definitions of fractional derivatives yield operators,
 which coincide on a wide domain and can be used
 in fractional partial differential equations.
 Then, the various definitions are useful in different purposes:
 they may be very close to some physics, or to numerical schemes,
 or be based upon important mathematical properties.
 Here we present a definition, which enables us to describe
 the flux of particles, performing  a random walk.
 We show that it is a left inverse to fractional integrals.
 Hence it coincides with Riemann-Liouville and Marchaud's derivatives
 when applied to functions, belonging to suitable domains.

Published May 15, 2007.
Math Subject Classifications: 26A33, 45K05, 60E07, 60J60, 60J75, 83C40.
Key Words: Diffusion equations; fractional calculus; random walks;
           stable probability distributions