Physical and numerical aspects of two-dimensional detonation simulations including detailed chemical kinetics on a massively parallel connection machine

The physical and numerical aspects of gas-phase detonation simulations performed on a massively parallel Connection Machine are presented. Contributions of this research include the development of a data parallel code for integrating unsteady, high-speed reactive flows, an examination of load balancing issues stemming from the data parallel integration of a chemical kinetic mechanism, and the first simulation of unsteady, gaseous detonations using a detailed chemical kinetic model. The results of this research indicate that SIMD and MIMD parallel architectures are suitable platforms for reactive flow simulations and the use of detailed chemical reaction models for detonation studies is important. The presence of globally-stiff chemical reactions was found to yield significant parallel inefficiencies as a result of poor load balancing of the processors. Consequently, a new load-balancing algorithm was developed that reduced the computer time required to integrate the chemical rate equations by a factor ranging from 2 to 12. This advance made the solution of new detonation problems possible. In particular, the simulation of a detonation in a {dollar}Hsb2/Osb2{dollar}/Ar (2:1:7) gas at 6.7 kPa was conducted using a detailed chemical kinetic model. The results were compared to previous simulations performed in a 6.0 cm channel in which a parametric chemistry model and the equations of state for a calorically perfect gas were used. Conclusions from the comparison are that the detailed chemical kinetic model predicts twice the number of detonation cells as the simplified chemistry model. The greatest discrepancy, however, between the parametric and detailed chemistry model predictions was the average detonation velocity. Other results from this study suggest that detonations propagating at velocities below the Chapman-Jouget value are dominated by wall viscous effects. Therefore, the value of comparisons between inviscid detonation simulations and experiments could be limited. In addition, new mechanisms for the formation of shock triple points and the reinitiation of the detonation cell are proposed. Finally, the first simulation to consider the effects of viscous transport on the interaction between the reaction front and the detonation shock structure was performed. The results indicated that viscosity and thermal conduction have little influence on the detonation structure.