Contributions to the Understanding of Large-Scale Coherent Structures in Developing Free Turbulent Shear Flows

Liu, J. T. C.

doi:10.1016/s0065-2156(08)70289-8

Cited by 74 publications

(46 citation statements)

References 122 publications

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“…Liu (1988) and Mankbadi and Liu (1984) adopted an intermediate approach in which the coherent motion was determined from integral conservation laws by using an approximate shape functions taken from linear instability theory.…”

Section: Unsteady Compressible Base Flowsmentioning

confidence: 99%

A generalized acoustic analogy

2003

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The purpose of this article is to show that the Navier-Stokes equations can be rewritten as a set of linearized inhomogeneous Euler equations (in convective form) with source terms that are exactly the same as those that would result from externally imposed shear stress and energy flux perturbations. These results are used to develop a mathematical basis for some existing and potential new jet noise models by appropriately choosing the 'base flow' about which the linearization is carried out.

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Section: Unsteady Compressible Base Flowsmentioning

confidence: 99%

A generalized acoustic analogy

2003

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“…Advances in such areas will most probably nccessitate a dramatic reduction in complexity by the removal of inessential degrees of freedom. The first real evidence that this reduction in complexity might be possible for fully developed turbulent flows came with the experimental discovery of coherent structures around the outbreak of the second world war, documented by J. T. C. Liu (1988). The existence of these structures was probably first articulated by Liepmann (1952), and was thoroughly exploited by Townsend (1956).…”

Section: Introduction 11 the Problems Of Turbulencementioning

confidence: 99%

The Proper Orthogonal Decomposition in the Analysis of Turbulent Flows

Berkooz¹,

Holmes²,

Lumley³

1993

Annu. Rev. Fluid Mech.

3,377

1,068

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“…Stuart [9] and Meksyn & Stuart [21] advanced the idea that a dominant mode suffices to represent the nonlinear disturbances which enter into the Reynolds stress for mean flow modification. This idea is found, in many instances, to hold for developing flows and in situations far from any weak nonlinear assumptions [20,22]. For the present, the most amplified helical n = ±1 modes according to the linear theory are assumed to represent the developing nonlinear modes (including consequential generation of other modes through nonlinear interactions), causing the modification of mean flow characteristics.…”

Section: (A) Estimate Of the Baseline Initial Disturbance Amplitudementioning

confidence: 95%

Modification of mean wake flow behind a very slender axisymmetric body of revolution by imposed nonlinear unstable helical modes

Lee

Liu

2014

Proc. R. Soc. A.

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For a sufficiently slender axially symmetric body placed in a uniform stream, only convectively unstable modes are found in previous experiments. This work imposes theoretically and computationally a pair of most unstable helical modes, symmetrically and asymmetrically. The Reynolds stress modification of the developing laminar mean wake flow is modified into an elliptic-like cross section for symmetrical forcing; the consequences of unequal upstream amplitudes are also explored. Energytransfer mechanisms between the mean flow and the relevant dominant modes and between the modes through 'triad interactions' are studied. The results from dynamical considerations provide the physical understanding of the generation of a standing wave mode at twice the azimuthal wavenumber; it is necessary that the wave envelopes of participating modes, including that of the mean flow, overlap in their spatial development, which is a necessary supplement to kinematical conditions for such interactions to take place effectively. Standing wave motions, which are otherwise only found naturally in wakes behind blunt-trailing-edge axisymmetric bodies, can be rendered present through appropriate forcing and nonlinear interactions behind very slender axisymmetric bodies.

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Contributions to the Understanding of Large-Scale Coherent Structures in Developing Free Turbulent Shear Flows

Cited by 74 publications

References 122 publications

A generalized acoustic analogy

A generalized acoustic analogy

The Proper Orthogonal Decomposition in the Analysis of Turbulent Flows

Modification of mean wake flow behind a very slender axisymmetric body of revolution by imposed nonlinear unstable helical modes

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