  Double-diffusive convection in porous media is a common phenomenon in nature,
and has received considerable attention in a wide variety of engineering
applications. In this paper, a multiple-relaxation-time (MRT) lattice Boltzmann
(LB) model is developed for simulating double-diffusive convection in porous
media at the representative elementary volume scale. The MRT-LB model is
constructed in the framework of the triple-distribution-function approach: the
velocity field, the temperature and concentration fields are solved separately
by three different MRT-LB equations. The present model has two distinctive
features. First, the equilibrium moments of the temperature and concentration
distributions have been modified, which makes the effective thermal diffusivity
and heat capacity ratio as well as the effective mass diffusivity and porosity
decoupled . This feature is very useful in practical applications. Second,
source terms have been added into the MRT-LB equations of the temperature and
concentration fields so as to recover the macroscopic temperature and
concentration equations. Numerical tests demonstrate that the present model can
serve as an accurate and efficient numerical method for simulating
double-diffusive convection in porous media.
