Mixing Regimes in a Spatially Confined, Two-Dimensional, Supersonic Shear Layer
NAVAL RESEARCH LAB WASHINGTON DC
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The evolution of a high-speed, compressible, confined, temporally evolving supersonic mixing layer between hydrogen and oxygen gas streams is examined using time-dependent, two-dimensional, numerical simulations that include the effects of viscosity, molecular diffusion, and thermal conduction. The flow shows three distinct mixing regimes an apparently ordered, laminar stage in which the structures grow due to the initial perturbation a convective-mixing regimes in which vortices begin to interact and structures grow and a diffusive-mixing regime in which vortical structures break down and diffusive mixing dominates. Varying the strength of the diffusion terms shows that these effects are important in the laminar and diffusive-mixing stages, but not in the convective mixing stage. Varying the convective Mach shows that compressibility does not change the general structural features of the mixing process, although higher compressibility results in a slower transition between the various flow regimes. Increasing the size of the computational domain increases the absolute time of transition from convective to diffusive mixing, but does not affect the dimensionless time normalized to the system size.
- Physical Chemistry