In this work we present a set of generalized diffusion equations that can describe anomalous diffusive processes. Nonlinearity, spatial and time-dependence in the coefficients and fractional derivatives, and combination of these alternatives as well, are some possible ways to generalize the usual diffusion equation. We verify that the composition of the indexes that characterize such strategies may conduct to subdiffusion, superdiffusion or even usual diffusion. A convenient choice of the time-dependent coefficients also leads to these processes. Thus, this procedure enlarges the spectrum of possibilities in the description of anomalous diffusive processes.
anomalous diffusion; diffusion equations
