We study vibrational energy relaxation of a "doorway model" (including the scissor,wagging and rocking mode) for nitromethane by molecular dynamics in collective interaction model.Relaxation time in vibrational cooling(VC) process agrees with experimental results.Frequency shifts for modes are consistent with experimental measurements at high-pressure in vibrational pumping(VP) process.VP process of nitromethane is observed in MD simulation in detail.It is shown that collective effects are important in vibrational energy relaxation at high-pressure and high-temperature,and energy of overtone-frequency as well as fundamental frequency of the modes must be taken into account in translational-vibrational energy transfer.

We employ the information preservation (IP) method and the direct simulation Monte Carlo (DSMC) method to calculate a plane Poiseuille flow from the continuum regime to the free-molecule flow regime.The Beskok-Karniadakis formula is corrected and kinetic factor of mass flow rate is re-fitted.A velocity distribution applicable to the entire flow regime is derived.

A kinetic approach, named as the information preservation (IP) technique, is used to simulate rarefied gas flows in micro channels under conditions where experimental data are available with about several thousand microns of channel lengths and about 0.135 of the largest Knudsen number at the outlet. Some issues for IP calculation of the long micro channels such as the computational stability and convergence speed are addressed. The calculated stream wise pressure distributions and mass fluxes are in agreement with experimental data.