A single-relaxation-time lattice Boltzmann model for anisotropic advection-diffusion equation based on the diffusion velocity flux formulation

In this paper, we describe a single-relaxation-time (SRT) lattice Boltzmann formulation, which can be effectively applied to anisotropic advection-dispersion equations (AADE). The formulation can be applied to space and time variable anisotropic hydrodynamic dispersion tensor. The approach utilizes diffusion velocity lattice Boltzmann formulation which in the case of AADE can represent anisotropic diagonal and off-diagonal elements of the dispersion matrix by the coupling of advective and diffusive fluxes in equilibrium function. With this approach, AADE can be applied to the SRT lattice Boltzmann formulation using the same equilibrium function and without any changes to collision step nor in the application of boundary conditions. The approach shows good stability even for highly anisotropic dispersion tensor and is tested on selected illustrative examples which demonstrate the accuracy and applicability of the proposed method.