Transitional rarefied flows over NACA 0012 airfoil in supersonic conditions: A DSMC investigation

Present study investigates the aerothermal characteristics of NACA 0012 airfoil in the transitional rarefied condition at supersonic speed. Direct simulation Monte Carlo (DSMC) approach has been used to resolve the rarefied flow fields with corresponding Knudsen number of 0.5, 1.0, 2.0 and 5.0. The freestream Mach number has been varied in the range of 2.0 to 4.0. The aerodynamic force action and heating are analyzed and found to be affected by the rarefication effects in the transitional flow regime. Results showed that with the increase of Knudsen number, the aerodynamic drag increases while the drag was reduced with increase of Mach number for the flow conditions studies in present investigation. Moreover, aerodynamic heating decreased with Knudsen number. Interestingly, the flow structure revealed that a series of diffusive waves are observed around the airfoil instead of shock waves which are conventionally observed in continuum supersonic flows.