  In this paper, the Lie symmetry analysis is proposed for a space-time
convection-diffusion fractional differential equations with the
Riemann-Liouville derivative by (2+1) independent variables and one dependent
variable. We find a reduction form of our governed fractional differential
equation using the similarity solution of our Lie symmetry. One-dimensional
optimal system of Lie symmetry algebras is found. We present a computational
method via the spectral method based on Bernstein's operational matrices to
solve the two-dimensional fractional heat equation with some initial
conditions.
