  Conventional cosmic-ray propagation models usually assume an isotropic
diffusion coefficient to account for the random deflection of cosmic rays by
the turbulent interstellar magnetic field. Such a picture is very successful in
explaining many observational phenomena related to the propagation of Galactic
cosmic rays, such as broken power-law energy spectra, secondary-to-primary
ratios, etc. However, the isotropic diffusion presupposition is facing severe
challenges from recent observations. In particular, such observations on the
large-scale anisotropy of TeV cosmic rays show that the dipole direction
differs from the prediction of the conventional model. One possible reason is
that the large-scale regular magnetic field, which leads to an anisotropic
diffusion of cosmic rays, has not been included in the model provided by the
public numerical packages. In this work, we propose two numerical schemes to
solve the $3$-dimensional anisotropic transport equation: the pseudo source
method and Hundsdorfer-Verwer scheme. Both methods are verified by reproducing
the measured B/C and proton spectrum and the radial variation of spectral index
expected by former 2D simulation. As a demonstration of the prediction
capability, dipole anisotropy is also calculated by a toy simulation with a
rough magnetic field.
