Analysis of Different Approaches to Modeling of Nozzle Flows in the Near Continuum Regime

Conical nozzle flows are studied for Reynolds numbers of 1,230 and 12,300 using different numerical techniques: DSMC Method. Navier-Stokes/CFD accounting for velocity slip and temperature jump boundary conditions, and statistical and deterministic approaches to the solution of BGK equation. Detailed comparison of the stability, accuracy, and convergence of the employed numerical techniques provides better understanding of their benefits and deficiencies, and assists in selecting the most appropriate technique for a particular nozzle and flow application. The deterministic and statistical solutions of the BGK equation were found to be in good agreement with the benchmark DSMC results. The Navier-Stokes solution differs from DSMC in the boundary layer.