Navier-Stokes simulations of two-dimensional compressible mixing layers

Navier-Stokes simulations of spatially developing unforced subsonic and supersonic mixing layers in a two-dimensional duct are carried out. The unsteady form of the governing equations is integrated by a second-order explicit finite volume upwind scheme. In both the subsonic and supersonic cases, we obtain self-sustained mixing layers without any external forcing. In the subsonic case, the similarities of the various first-order statistical quantities are in reasonable agreement with experimental data. Similar results are also obtained in a supersonic case in which the reflected Mach waves emitted from a splitter plate are responsible for sustaining an unforced mixing layer.