Computational Modeling of Nearfield to Farfield Plume Expansion

*† ‡ § ** A hybrid continuum/non-continuum methodology is being developed to model flows in which rarefaction effects are important while the continuum approach is accurate for parts of the flowfield. Depending on altitude, rocket and missile exhaust plume expansion can be modeled using a combination of continuum, direct simulation Monte Carlo (DSMC), or freemolecular (FM) techniques. The ability to automatically couple these techniques allows for efficient and accurate modeling of length scales on the orders of km’s from the nozzle exit plane, and parametric studies can easily be performed. The methodology is demonstrated for an axisymmetric (0 angle of attack) and a 3D (>0 angle of attack) missile configuration. For the latter calculations, the DSMC solution is coupled to an outer DSMC simulation and a FM code. The Automatic Efficient Generalized Interface Surface Toolkit (AEGIS Toolkit) which enables the coupling between the continuum and DSMC codes is described. Extensions to the methodology for particulates and unsteady flow phenomena are among the capabilities.