Flow and Heat Transfer Characteristics in High Speed Flows through Nano Scale Conduits Using DSMC-IP Method

The fluid flow behavior and heat transfer characteristics in nano channels and nano nozzles at different Mach and Knudsen numbers are studied using Direct Simulation Monte Carlo (DSMC) and Information Preservation (IP) methods. The study is carried on both supersonic and subsonic flow regimes. In the supersonic regime, nano-Poiseuille flow is simulated at two different Knudsen Numbers of 0.06 and 0.74 of which the latter one occurs in transition regime. To expand our study, we investigate the effect of back pressure and transport properties on nitrogen and helium flow behaviors. We also discuss the interaction between the generated oblique shock waves and boundary layer. A behavior similar to the one predicted by the classical theories such as that of Fanno theory, is observed in low Knudsen number regimes. Next, the heat and flow behaviors are studied in convergent-divergent nano nozzles. We elaborate the effects of pressure ratio across the nozzle on the mass flow rate, choking, and the generated thrust in a series of cases. The results show good agreement with the analytical Navier-Stokes-based solutions. The heat transfer results are also compared with the analytical solutions derived from Rayleigh theory. Eventually, we also discuss the nozzle half-angle expansion magnitude on subsonic boundary layer and the generated thrust.