On the structure and patterns of von Kármán vortices in two-dimensional high Reynolds number flows

Lewis, David; Radko, Timour

doi:10.1063/5.0022537

Cited by 3 publications

(2 citation statements)

References 42 publications

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Section: Proposed Methodsmentioning

confidence: 99%

“…In the inversion of submarine maneuvering state, the evolution of the submarine wake vortex is uncertain, leading to random changes in the characteristics of the wake vortex [42]. Te observed submarine wake vortex is modeled as set M, and the submarine steering state is modeled as set N. Te observation feature set of submarine wake vortex and the manipulation state set of submarine are, respectively, expressed as follows:…”

Section: Proposed Methodsmentioning

confidence: 99%

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An Improved Wake Vortex‐Based Inversion Method for Submarine Maneuvering State

Kong

Yang

Cai

et al. 2023

Computational Intelligence and Neuroscience

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As the noise reduction performance of submarines continues to improve, it is difficult to detect and track submarines through acoustic detection techniques. Therefore, nonacoustic submarine detection techniques are becoming more and more important. The submarine movement will leave a wake vortex, and the information of the wake vortex can be used to invert the maneuvering state of the submarine. However, the wake vortex is constantly dissipated in the evolution process, and the strength of the wake vortex is constantly reduced, resulting in the gradual weakening of the characteristics of the wake vortex, which makes the inversion of submarine operating state difficult and less accurate. In order to solve the above problems, this paper proposes an improved wake vortex-based inversion method for submarine maneuvering state. Firstly, a random finite set of submarine wake vortex observation features is established to obtain the feature with the highest correlation degree with submarine maneuvering state in the random finite set. Secondly, the multiscale fusion module and attention mechanism are used to re-encode the weak features of the wake vortex image, and the salient features of the wake vortex image are extracted. Finally, the manipulation state of the wake vortex image is retrieved by the extracted salient features. The experimental results show that the average inversion accuracy of the proposed algorithm is improved by 1.27% in terms of manipulating state inversion of weak feature wake vortex images. The algorithm in this paper can realize the inversion of submarine maneuvering state in the case of weak submarine wake vortex image features and incomplete feature information. It provides the basis for the detection technology based on the submarine wake characteristics.

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Section: Proposed Methodsmentioning

confidence: 99%

Section: Proposed Methodsmentioning

confidence: 99%

An Improved Wake Vortex‐Based Inversion Method for Submarine Maneuvering State

Kong

Yang

Cai

et al. 2023

Computational Intelligence and Neuroscience

View full text Add to dashboard Cite

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von Kármán vortex streets around invisible bluff bodies

Vadasz

2023

Physics of Fluids

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Satellite images captured during the past decade identify clearly von Kármán vortex streets in the atmosphere above certain islands in the Atlantic and Pacific Oceans. The vortex streets are visible due to the cloud formations since the latter behave as unintended tracers of the fluid motion driven by winds. Experimental as well as numerical simulation results of von Kármán vortex shedding for flow around a cylinder or other bluff body identify the latter in a certain range of Reynolds numbers. The satellite images, however, show these von Kármán vortex structures at elevations well above the ground level inviting the appealing question of where is the cylinder or the bluff body? This short paper identifies the answer to this question as the creation of Taylor–Proudman columns above the islands that are invisible until a tracer makes them detectable at a certain height above the island. The latter also provides the clarification that the flow is geostrophic at the leading order and consequently two-dimensional (i.e., variations occur in the horizontal directions with no leading order changes in the vertical direction). In addition, this paper shows that a small Rossby number is not a necessary requirement for the creation of Taylor–Proudman columns. The latter can emerge also if a certain modified Beltrami condition is satisfied even when Rossby number is not small.

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