| Numerical simulations of confined supersonic shear layers have been conducted using advanced massively parallel computing systems and a high performance scientific programming language. The fundamental capability sought was the ability to model the steady and unsteady behavior of confined compressible shear layer mixing, at least to within the conventional guidelines for the resolution of important physical phenomena. The overall objective was fully achieved.; The development of the software was accomplished on a combination of a CM-200a situated at Penn State, the Numerical Aerodynamic Simulation Program's CM-5 at NASA Ames, and the National Center for Supercomputing Application's CM-5 at the University of Illinois at Urbana-Champaign. A system specific version of High Performance Fortran, CM Fortran, was used to code the software. The Euler equations were integrated with the MacCormack 2-4 numerical scheme applied over a Cartesian grid. Several new developments such as a modified Jameson Artificial Viscosity scheme, a new spatial extrapolation scheme, and new unsteady inlet boundary conditions, resulted in excellent comparison with experimental data. The supersonic shear layers were simulated using dense grids to provide a fine-grain resolution of the mixing layer. Grid densities were chosen to resolve the fundamental Kelvin-Helmholtz instability mode and the very thin shear layer near the inlet. The fine grain solutions utilize approximately 200,000 grid points in the 2-D cases and 5,250,000 grid points in the 3-D case.; Two compressible mixing layers were simulated and compared to experimental data collected under a separate effort. Similarly, single frequency excitation simulations were made to provide comparisons with linear stability theory. Both shear layers have moderate Reynolds numbers ({dollar}Reysb{lcub}deltaomega{rcub}{dollar}) of 6600 and 9500, and have convective Mach numbers of 0.5 and 0.64, respectively. Very good agreement between the two-dimensional simulation and experimental results were obtained for the mean velocity profiles, FFT spectra, shear layer growth rate, momentum fluctuation quantities and the Reynolds stresses. Examination of instantaneous and time-averaged field variables provided informative insight into; shear layer growth rate behavior, double peaked turbulence intensity profiles that are commonly observed in experimental data, and shear layer excitation by standing Mach waves reflected from the confining channel walls. |
