Numerical Modeling of Near-Continuum Flow over a Wedge with Real Gas Effects

Abstract

Effects of vibrational relaxation and dissociation on the standoff distance of the bow shock wave on a wedge are numerically examined with the use of the kinetic (DSMC method) and continuum (Navier-Stokes equations) approaches. A hypersonic flow around the wedge is computed for Knudsen numbers about 5 x 10 -4 in a wide range of wedge angles both for a monatomic gas (argon) and a diatomic reacting and nonreacting gas (nitrogen). DSMC computations are based on three different real gas effect models. The kinetic and continuum results for the standoff distance are in good agreement for argon and nonreacting nitrogen. The influence of vibration-dissociation coupling on the results of numerical simulations is analyzed. Sensitivity of simulation results to chemical reaction rate constants is also estimated. Numerical simulations show that dissociation is responsible for the nonlinear form of the dependence of the standoff distance on the wedge angle, which qualitatively agrees with available experimental data.