We adopted lattice Boltzmann method to simulate double diffusion mixed convection, fluid-solid conjugate heat transfer and adsorption process in a lid-driven composite enclosure filled with homogeneous medium at pore scale. Influences of buoyancy ratio Br (-100 ≤ Br ≤ 100) and adsorption rate constant k₁ (0.001 ≤ k₁ ≤ 0.005) on characteristics of heat and mass transfer were compared at porosity ε=0.79, Prandtl number Pr=0.7, Grashof number Gr=10⁴ and Lewis number Le=1.0. Streamlines, isotherms, isoconcentrations, adsorption capacity (C_S), average Nusselt number Nu_av and Sherwood number Sh_av of the left heated wall under different parameters were discussed in detail. It shows that Br affects adsorption by changing concentration distribution around medium in flow field; Increasing k₁ improves significantly adsorption efficiency and adsorption capacity.

We adopt lattice Boltzmann method to investigate double diffusive natural convection around a heated cylinder in an enclosure with Soret and Dufour effects. The inner heated cylinder is located at center of a square enclosure and four surrounding walls are assumed with low temperature and concentration. In the model, distributions of velocity, temperature and concentration are solved with three independent LBGK equations which are combined into a coupled equation through Boussinesq approximation. Influences of Soret number and Dufour number on double diffusive natural convection are analyzed. Streamlines, isotherms, isoconcentrations, average Nusselt and Sherwood numbers around heated cylinder in enclosure are presented. It shows that Soret and Dufour effects have significant influence on double diffusive natural convection.

Lattice Boltzmann method is adopted to investigate mixed convection in an enclosure filled with porous medium.A heated cylinder (D/L=0.4) is located at center of the enclosure with high temperature.Inlet flow with low temperature is located at lower-left wall of the enclosure and exit is at upper-left wall.Other walls are assumed adiabatic.Influences of Richardson number Ri and Darcy number Da on average Nusselt number Nu around heated cylinder are investigated while Prandtl and Grashof numbers are kept at 0.71 and 1.4×10⁴, respectively.It indicates that Nu decreases with increasing Ri.Influence of Richardson number on Nu is significant as Darcy number is great.At 10^-5≤Da≤10^-2, Nu increases with increasing Darcy number as forced convection dominates flow (Ri≤0.1).As natural convection dominates flow (Ri=10), Nu is not sensitive to Darcy number.

Lattice Boltzmann method is adopted to numerically analyze nonlinear characteristics of double diffusive mixed convection in an enclosure. A heated cylinder is located at center of the enclosure. Fluid flows from an inlet at lower-left wall of enclosure and an outlet is at upper-right,upper-middle and upper-left wall respectively. Simulation results indicate that there are steady stationary solution,periodic and aperiodic oscillatory solutions in double diffusive mixed convection at different parameters. Phase path of velocity of monitoring point finally reaches a point,a closed loop and irregular curves,respectively.