Journal ArticleDOI
Compressible mixing layer - Linear theory and direct simulation
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TLDR
In this paper, a linear stability analysis is presented for a wide variety of mixing layers, including low-speed and high-speed layers with variable density and high Mach number mixing layers.Abstract:
Results from linear stability analysis are presented for a wide variety of mixing layers, including low-speed
layers with variable density and high Mach number mixing layers. The linear amplification predicts correctly the
experimentally observed trends in growth rate that are due to velocity ratio, density ratio, and Mach number,
provided that the spatial theory is used and the mean flow is a computed solution of the compressible
boundary-layer equations. It is found that three-dimensional modes are dominant in the high-speed mixing layer
above a convective Mach number of 0.6, and a simple relationship is proposed that approximately describes the
orientation of these waves. Direct numerical simulations of the compressible Navier-Stokes equations are used
to show the reduced growth rate that is due to increasing Mach number. From consideration of the compressible
vorticity equation, it is found that the dominant physics controlling the nonlinear roll-up of vortices in the
high-speed mixing layer is contained in an elementary form in the linear eigenfunctions. It is concluded that the
linear theory can be very useful for investigating the physics of free shear layers and predicting the growth rate
of the developed plane mixing layerread more
Citations
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Journal ArticleDOI
Three-dimensional simulations of large eddies in the compressible mixing layer
TL;DR: In this paper, the effect of compressibility on a plane mixing layer that is a prototype free shear layer, amenable to study by numerical simulation and experiment, is considered, and the full time-dependent compressible Navier-Stokes equations are solved numerically for a temporally evolving mixing layer employing a mixed spectral and high-order finite difference method.
Journal ArticleDOI
Recent advances in aero-optics
TL;DR: A brief discussion of the traditional approach to quantifying aero-optic interactions is given in this paper, where the authors review how the development of high-speed wavefront sensors over the past 10 years has impacted the fluid-dynamics and optics fields.
Journal ArticleDOI
Mixing enhancement in supersonic free shear flows
TL;DR: In this article, the mixing augmentation methods employed efficiently in sub- sonic flows failed to work at elevated Mach numbers, and some were inefficient because they were utilized outside their effective range.
Journal ArticleDOI
Compressible mixing layer growth rate and turbulence characteristics
TL;DR: In this paper, the effect of compressibility on mixing layers was investigated using direct numerical simulation databases and it was found that the dilatational contribution to dissipation is negligible even when eddy shocklets are observed in the flow.
References
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Book
Viscous Fluid Flow
TL;DR: In this article, the stability of Laminar Boundary Layer Flow Appendices has been investigated in Cylindrical and Spherical Coordinates of Incompressible Newtonian Fluids.
Journal ArticleDOI
On density effects and large structure in turbulent mixing layers
Garry L. Brown,Anatol Roshko +1 more
TL;DR: In this article, Spark shadow pictures and measurements of density fluctuations suggest that turbulent mixing and entrainment is a process of entanglement on the scale of the large structures; some statistical properties of the latter are used to obtain an estimate of entrainedment rates, and large changes of the density ratio across the mixing layer were found to have a relatively small effect on the spreading angle.
Journal ArticleDOI
The compressible turbulent shear layer: an experimental study
TL;DR: In this paper, the growth rate and turbulent structure of the compressible, plane shear layer are investigated experimentally in a novel facility, where it is possible to flow similar or dissimilar gases of different densities and to select different Mach numbers for each stream.
Journal ArticleDOI
Time-dependent boundary conditions for hyperbolic systems, II
TL;DR: In this article, nonreflecting boundary conditions are defined for multidimensional fluid dynamics problems where waves enter and leave the interior of a domain modeled by hyperbolic equations, and separate equations for each type of incoming and outgoing wave.
Journal ArticleDOI
Absolute and convective instabilities in free shear layers
TL;DR: The absolute or convective character of inviscid instabilities in parallel shear flows can be determined by examining the branch-point singularities of the dispersion relation for complex frequencies and wavenumbers.
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