Unified Kinetic/Continuum Flow Solver with Adaptive Cartesian Mesh for Hypersonic Flows in the Earth Atmosphere

The design of future hypersonic vehicles requires detailed understanding of flow regimes ranging from rarefied to continuum. Hypervelocity flows are characterized by high temperatures, real gas effects, nonequilibrium chemistry, and ionization. The goal of this project is to develop unified kinetic/continuum solution methods with automatic domain decomposition for a wide range of Air Force applications. The Unified Flow Solver (UFS) with Adaptive Mesh and Algorithm Refinement, developed by CFDRC, will be enhanced by advanced capabilities of the NASCART-GT viscous flow solver from Georgia Tech. The octree based Cartesian mesh methods used in both codes will be improved to better resolve viscous boundary layers and heat transfer simulations near surfaces. Phase I work has demonstrated the feasibility of an immersed boundary method to greatly improve heat transfer simulations with Cartesian mesh. UFS coupling with the general-purpose chemistry solver CANTERA allowed solving stiff chemistries for hypersonic flows. Adaptive mesh in velocity space was introduced to increase efficiency of the Boltzmann solver. During Phase II, these advanced numerical techniques will be incorporated into a user-friendly code. The code will be validated for heat transfer simulations with Cartesian mesh and demonstrated for several benchmark cases including heat transfer predictions in hypersonic rarefied, transitional and continuum flows. BENEFIT: The code will be used as a design tool for development of future hypersonic vehicles. In addition to Air Force applications, the code will be useful for a multitude of NASA technology development programs under Project Constellation and the New Millennium Program. Missile defense applications include Theater and Ballistic Missile Defense vehicles performing exo-atmospheric missile intercept, such as the Ground Based Midcourse Defense, Aegis, and Multi-Kill Vehicle programs. Commercial applications include material processing, vacuum science, and nanotechnologies.