  Two-dimensional Rayleigh-Taylor(RT) instability problem is simulated with a
multiple-relaxation-time discrete Boltzmann model with gravity term. The
viscosity, heat conductivity and Prandtl number effects are probed from the
macroscopic and the non-equilibrium views. In macro sense, both viscosity and
heat conduction show significant inhibitory effect in the reacceleration stage,
and the inhibition effect is mainly achieved by inhibiting the development of
Kelvin-Helmholtz instability. Before this, the Prandtl number effect is not
sensitive. Based on the view of non-equilibrium, the viscosity, heat
conductivity, and Prandtl number effects on non-equilibrium manifestations, and
the correlation degrees between the non-uniformity and the non-equilibrium
strength in the complex flow are systematic investigated.
