  The purposes of this paper are testing an efficiency algorithm based on LBM
and using it to analyze two-dimensional natural convection with low Prandtl
number. Steady state or oscillatory results are obtained using double
multiple-relaxation-time thermal lattice Boltzmann method. The velocity and
temperature fields are solved using D2Q9 and D2Q5 models, respectively. With
different Rayleigh number, the tested natural convection can either achieve to
steady state or oscillatory. With fixed Rayleigh number, lower Prandtl number
leads to a weaker convection effect, longer oscillation period and higher
oscillation amplitude for the cases reaching oscillatory solutions. At fixed
Prandtl number, higher Rayleigh number leads to a more notable convection
effect and longer oscillation period. Double multiple-relaxation-time thermal
lattice Boltzmann method is applied to simulate the low Prandtl number fluid
natural convection. Rayleigh number and Prandtl number effects are also
investigated when the natural convection results oscillate.
