Within Homogeneous Turbulence: Crow Instability Large Eddy Simulation of Aircraft Wake Vortices

Han, Je-Chin; Lin, Yuh-Lang; Schowalter, David; Arya, S. Pal; Proctor, Fred H.

doi:10.2514/2.956

Cited by 35 publications

(10 citation statements)

References 20 publications

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“…Stronger turbulence accelerates the onset of the instability, leading to shorter contrail descent and more effective mixing in the interior of the plume. These results are in line with those published in recent wake vortex literature (Holzäpfel et al, 2001;Hennemann and Holzäpfel, 2011;Misaka et al, 2012) -although the latter authors analyzed weaker turbulence scenarios than ours -and are then a solid basis to investigate their impact on contrail microphysics. These effects influence the lifetime of the vortices, the vertical extent of the contrail, and the number of surviving crystals.…”

Section: Discussionsupporting

confidence: 92%

“…The integral length scale (estimated as L t = 3π 4K ∞ 0 E(k) k dk, with K = 1/2(σ 2 u +σ 2 v +σ 2 w ) as the turbulent kinetic energy, k the horizontal wave number, and E(k) the kinetic energy horizontal spectrum) ranged between 700 and 1 km. Because the ratio L t /b 1, the integral length scale does not significantly affect the vortex decay as observed in previous studies (e.g., Crow and Bate, 1976;Hennemann and Holzäpfel, 2011). When the atmospheric turbulent flow field is truncated within the smaller domain denoted by the black box in Fig.…”

Section: Discussionmentioning

confidence: 71%

“…Typical perturbations include sinusoidal waves corresponding to the excited instability modes (Laporte and Corjon, 2000;Le Dizès and Laporte, 2002;Paugam et al, 2010), broadband white noise, and spectral perturbations satisfying model spectra of isotropic or anisotropic turbulence. The latter approach has been used in the wake vortex literature and particularly in the studies that attempted to analyze the interaction of the wake with the background turbulence (Lewellen and Lewellen, 1996;Gerz and Holzäpfel, 1999;Han et al, 2000;Holzäpfel et al, 2001) and more recently by Hennemann and Holzäpfel (2011) who focused on the identification of vortex flow topology, and by Misaka et al (2012) who analyzed passive scalar transport in addition to the fine-scale structures of the wake. The main difference with the present study is that here the background turbulence is sustained, yet the threedimensional snapshots shown in these studies as well as the various pictures of wake instabilities reported in the literature Crow (1970), Chevalier (1973), and Sussmann and Gierens (1999) corroborate the structures visualized in Fig.…”

Section: Dynamics Of Wake Vorticesmentioning

confidence: 99%

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Large-eddy simulations of contrails in a turbulent atmosphere

Picot¹,

Paoli²,

Thouron³

et al. 2014

Preprint

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Abstract. In this work, the evolution of contrails in the vortex and dissipation regimes is studied by means of fully three-dimensional large-eddy simulation (LES) coupled to a Lagrangian particle tracking method to treat the ice phase. This is the first paper where fine-scale atmospheric turbulence is generated and sustained by means of a stochastic forcing that mimics the properties of stably stratified turbulent flows as those occurring in the upper troposphere lower stratosphere. The initial flow-field is composed by the turbulent background flow and a wake flow obtained from separate LES of the jet regime. Atmospheric turbulence is the main driver of the wake instability and the structure of the resulting wake is sensitive to the intensity of the perturbations, primarily in the vertical direction. A stronger turbulence accelerates the onset of the instability, which results in shorter contrail decent and more effective mixing in the interior of the plume. However, the self-induced turbulence that is produced in the wake after the vortex break-up dominates over background turbulence at the end of the vortex regime and dominates the mixing with ambient air. This results in global microphysical characteristics such as ice mass and optical depth that are be slightly affected by the intensity of atmospheric turbulence. On the other hand, the background humidity and temperature have a first order effect on the survival of ice crystals and particle size distribution, which is in line with recent and ongoing studies in the literature.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 71%

Section: Dynamics Of Wake Vorticesmentioning

confidence: 99%

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Large-eddy simulations of contrails in a turbulent atmosphere

Picot¹,

Paoli²,

Thouron³

et al. 2014

Preprint

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“…In these simulations, the detailed temporal evolution of a vortex pair with an initially longitudinally constant velocity profile is investigated allowing for the formation of cooperative instabilities, e.g., short-wave (elliptic) instability 7-10 and Crow instability. [11][12][13][14] Various atmospheric conditions of turbulence, stability, and wind shear have been considered in order to assess the influence of these factors on wake vortex evolution and decay. 15,16 However, little is known about the further evolution of the vortex rings formed as a consequence of the Crow instability in particular under different environmental conditions.…”

Section: Introductionmentioning

confidence: 99%

Vortex bursting and tracer transport of a counter-rotating vortex pair

et al. 2012

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Large-eddy simulations of a coherent counter-rotating vortex pair in different environments are performed. The environmental background is characterized by varying turbulence intensities and stable temperature stratifications. Turbulent exchange processes between the vortices, the vortex oval, and the environment, as well as the material redistribution processes along the vortex tubes are investigated employing passive tracers that are superimposed to the initial vortex flow field. It is revealed that the vortex bursting phenomenon, known from photos of aircraft contrails or smoke visualization, is caused by collisions of secondary vortical structures traveling along the vortex tube which expel material from the vortex but do not result in a sudden decay of circulation or an abrupt change of vortex core structure. In neutrally stratified and weakly turbulent conditions, vortex reconnection triggers traveling helical vorticity structures which is followed by their collision. A long-lived vortex ring links once again establishing stable double rings. Key phenomena observed in the simulations are supported by photographs of contrails. The vertical and lateral extents of the detrained passive tracer strongly depend on environmental conditions where the sensitivity of detrainment rates on initial tracer distributions appears to be low.

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“…As early CONTACT Dong Li ldgh@nwpu.edu.cn as 1970, Crow proposed that under the induction of reverse counter-rotating vortices, not only the shortwave instability of vortices but also the long-wave instability is an important factor affecting the decay of wake vortices and this is called the Crow instability (Crow, 1970). It is closely related to ambient atmospheric conditions (Bieniek et al, 2016;Gerz & Holzapfel, 1999;Han, et al, 2000), so the generation of ambient turbulence is a key part of the numerical method used to study the evolution of wake vortices. The spectrum method is an effective tool for generating homogeneous isotropic turbulence (Bauer & Zeibig, 2006;Chatterjee & Mohamed, 2014;Lin et al, 2016;Vincent & Meneguzzi, 1991).…”

Section: Introductionmentioning

confidence: 99%