Anomalous diffusion and fractional diffusion equation: anisotropic media and external forces

We analyze a fractional diffusion equation by taking an anisotropic case into account. In our analysis, we also consider a spatial time dependent diffusion coefficient and the presence of external forces in the system. For the cases analyzed here, we obtain exact solutions and show that the solutions have an anomalous spreading. In addition, we discuss a rich class of diffusive processes, including normal and anomalous ones described by this equation.