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  • 1
    Electronic Resource
    Electronic Resource
    BIFURCATING AND BLOOMING JETS (2003)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 35 (2003), S. 295-315 
    Details
    ISSN: 0066-4189
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract It is classically assumed that the far field of a round turbulent jet discharging into quiescent fluid has a unique behavior characterized only by its momentum flux. However, there is now considerable evidence that different discharge conditions at the jet nozzle exit can give rise to very different far-field flows. Perhaps the most striking examples of these are the bifurcating and blooming jets produced by appropriate combinations of controlled axial and circumferential excitations at the nozzle exit. With the right excitations, a jet can be made to divide into two separate jets (bifurcating jet), each of which carries half the axial momentum and spreads in a manner similar to a single jet. Trifurcating jets can also be produced. Other excitations can produce blooming jets, in which the jet explodes into a shower of vortex rings, producing a far-field flow that is quite unlike a normal unexcited jet. Bifurcating and blooming jets exhibit much greater mixing than normal jets, suggesting possible applications in flow control. This article summarizes our work on bifurcating and blooming jets, which began with our discovery of them in the early 1980s and continued through the mid- 1990s. One of us (D.E.P.) continued exploration of flow control using excited jets, first at the McDonnell Douglas Corporation, and more recently at the Georgia Institute of Technology. The key to flow control is the manipulation of the large vortical structures in the near field of the jet. Ultimately this work, and that of others, led to full-scale testing of jet engine exhaust mixing control. There it was shown that the jet temperature downstream of the engine can be very significantly reduced by application of well-designed and easily implemented excitation at the engine discharge, thereby solving problems encountered during ground operations. Related jet control work by other investigators is included in this review.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.fluid.35.101101.161128
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  • 2
    Electronic Resource
    Electronic Resource
    Computation of Turbulent Flows (1976)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 8 (1976), S. 183-208 
    Details
    ISSN: 0066-4189
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.fl.08.010176.001151
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  • 3
    Electronic Resource
    Electronic Resource
    Passive scalar tagging for the study of coherent structures in the plane mixing layer (1989)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 1 (1989), S. 2034-2041 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Data obtained from the two-dimensional numerical simulation of a plane mixing layer have been used to study the feasibility of tagging one side of the flow by a passive scalar and using the instantaneous concentration of the scalar to detect the typical coherent events in the flow. The study has shown that this technique works quite satisfactorily and yields results similar to those obtained by using the instantaneous vorticity as a detection criterion. The contribution from the coherent events to the time-averaged turbulent momentum and scalar transport has been estimated. It is found that this contribution is of the same order as the time-mean transport during most of the dynamical evolution of the coherent structure. However, it may attain very large values for short periods of time in the neighborhood of pairing. The increase is particularly spectacular in the case of the Reynolds shear stress. While the present findings obtained from a two-dimensional simulation seem to support earlier results obtained from actual experiments, it is desirable to conduct additional studies with three-dimensional simulations when they become available.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.857477
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  • 4
    Electronic Resource
    Electronic Resource
    Structure and scales in turbulence modeling (2002)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 14 (2002), S. 2485-2492 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The enstrophy of the large-scale energy-containing turbulence is proposed as the second turbulence scale for use, in conjunction with the turbulence energy, in two-scale one-point engineering turbulence models. Its transport equation is developed in general and modeled for homogeneous turbulence in terms of the two scales and our new one-point structure tensors. The model produces the correct behavior of the scales for both two- and three-dimensional turbulence. Constants in the high Reynolds number model are evaluated only by reference to asymptotic analysis for decaying turbulence in stationary and rotating frames, and this model is then shown to provide an excellent prediction of homogeneous turbulent shear flow when used with the structure tensors for that flow. The low Reynolds number constant in the model is evaluated using the asymptotic decay rate for isotropic turbulence at zero Reynolds number, and numerical simulations of decay for intermediate Reynolds numbers are used to establish one remaining constant, the value of which does not affect high Reynolds number predictions. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1473784
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  • 5
    Electronic Resource
    Electronic Resource
    On the Yakhot–Orszag renormalization group method for deriving turbulence statistics and models (1992)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 4 (1992), S. 364-390 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The purpose of this paper is to provide an independent, comprehensive, critical review of the "renormalization group'' theory of turbulence developed by Yakhot and Orszag [J. Sci. Comput. 1, 3 (1986)]. The first part of the paper is a confirmation of their basic theory for the Navier–Stokes equations, followed by a discussion of approximations in the scale removal procedure. The main part of the paper examines the YO derivations of the velocity-derivative skewness and the transport equation for the energy dissipation rate E. An algebraic error in the derivation of the skewness is corrected. Several problems are identified in the derivation of the E equation which suggest that the derivation should be reformulated. The present paper has become the basis for such a reformulation, to be published separately by Yakhot and Smith.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.858310
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  • 6
    Electronic Resource
    Electronic Resource
    Dynamic response of boundary-layer turbulence to oscillatory shear (1991)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 3 (1991), S. 178-187 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The temporal response of a well-developed turbulent boundary layer to the superposition of oscillatory shear has been measured experimentally, over a wide range of frequencies. The response is primarily a periodic organization in magnitude of components of the turbulent velocity field at the forcing frequency. Oscillatory production of turbulence arises predominantly as a modulation of the mean production process in the parent boundary layer. Close to the wall, the relative phases of response of components of turbulent kinetic energy indicate that temporal redistribution of turbulent kinetic energy is driven by robust coherent motions of the underlying mean flow. The local directions of redistribution deduced from these measurements indicate a wall impingement (splatting) effect, consistent with characterizations from numerical simulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.857877
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  • 7
    Electronic Resource
    Electronic Resource
    Compressibility effects on the passive scalar flux within homogeneous turbulence (1994)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 6 (1994), S. 3498-3500 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Compressibility effects on turbulent transport of a passive scalar are studied within homogeneous turbulence using a kinematic decomposition of the velocity field into solenoidal and dilatational parts. It is found that the dilatational velocity does not produce a passive scalar flux, and that all of the passive scalar flux is due to the solenoidal velocity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.868406
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  • 8
    Electronic Resource
    Electronic Resource
    Structure-based turbulence model: Application to a rotating pipe flow (2002)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 14 (2002), S. 1523-1532 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A new approach for modeling the one-point turbulence statistics, which takes into account the information on turbulence structure, has been suggested in Kassinos and Reynolds (Report TF-61, Thermosciences Division, Department of Mechanical Engineering, Stanford University, 1994). In the present work, the structure-based model [Int. J. Heat Fluid Flow 21, 599 (2000)] (SBM) based on those ideas, was evaluated in a complex inhomogeneous turbulent flow in a cylindrical pipe rotating around its longitudinal axis. It was found that the SBM is able to predict the flow accurately at various Reynolds numbers and under stronger rotation than what is possible with the Reynolds stress transport models (RSTMs). In a fully developed rotating pipe flow, the SBM, being a linear model, slightly improves the profiles obtained with the nonlinear RSTM [J. Fluid Mech. 227, 245 (1991)]. However, if the standard equation for the dissipation rate is used, the SBM, as do the RSTMs, significantly overpredicts the turbulent kinetic energy level in this part of flow in comparison with the results of experiments. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1458008
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  • 9
    Electronic Resource
    Electronic Resource
    Parametrizing the growth rate influence of the velocity ratio in compressible reacting mixing layers (1998)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 10 (1998), S. 2686-2688 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The ability of the velocity ratio parameter λ=(U1−U2)/(U1+U2) to scale linear stability amplification rates for a compressible reacting and compressible variable-density mixing layer is reported. Extensions to the definition of λ to reflect the dominance of outer modes in the flow structure at significant levels of heat release and compressibility are proposed and their performance is evaluated. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.869786
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  • 10
    Electronic Resource
    Electronic Resource
    The structure of the compressible reacting mixing layer: Insights from linear stability analysis (1998)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 10 (1998), S. 993-1007 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Previous investigations have demonstrated that a compressible reacting mixing layer can develop two instability modes in addition to the more common central mode that exists unaccompanied in incompressible nonreacting flows. These two additional modes are termed "outer" because of their association with the fast and slow free streams. Numerical simulations have shown that mixing layers dominated by outer modes have a lower global reaction rate in comparison to a flow structure governed by the central mode. Therefore, the presence of these modes has important consequences for applications in supersonic combustion. Results are presented from a parametric study of the compressible reacting mixing layer's regime space using linear stability analysis. The focus of our work is to develop a better understanding for the combined effects of compressibility, heat release and the ratios of density, equivalence, and velocity on the instability characteristics of each mode and on the structure predicted to result in a turbulent reacting mixing layer. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.869619
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