Wakes and free surface signatures of a generic submarine in the homogeneous and linearly stratified fluid

Huang, Fenglai; Meng, Qingjie; Cao, Liushuai; Wan, Decheng

doi:10.1016/j.oceaneng.2022.111062

Cited by 25 publications

(8 citation statements)

References 43 publications

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“…Numerical simulations revealed that wakes on the ocean surface generated by submerged vehicles are wider, last longer and propagate further when the medium is stratified compared to a homogeneous medium. 13 Underwater, there are critical speed and depth parameter combinations where the internal wake wave pattern dominates over the Kelvin wake, as shown in Fig. 5.…”

Section: Internal Wavesmentioning

confidence: 99%

“…The internal Froude number is used to characterise different levels of stratification. 13 The internal Froude number is defined as F r = u N D , where u is the object's speed, D is the characteristic length and N is the Brunt-Väisälä frequency, given by N = − g ρ ∂ρ ∂z . [13][14][15] It defines the level of stratification and is the frequency a particle will oscillate in a stratified environment.…”

Section: Introductionmentioning

confidence: 99%

“…Here, ρ is the density of the fluid, ∂ρ ∂z denotes the instantaneous change in the density and g is the acceleration due to gravity. 13 The product N t, where t is the wake evolution time in seconds, is a common non-dimensional time used to describe the development of the wake. 16 For F r << 1, the fluid is stratified and vertical motion is inhibited.…”

Section: Introductionmentioning

confidence: 99%

“…13 The internal Froude number is defined as F r = u N D , where u is the object's speed, D is the characteristic length and N is the Brunt-Väisälä frequency, given by N = − g ρ ∂ρ ∂z . [13][14][15] It defines the level of stratification and is the frequency a particle will oscillate in a stratified environment. Here, ρ is the density of the fluid, ∂ρ ∂z denotes the instantaneous change in the density and g is the acceleration due to gravity.…”

Section: Introductionmentioning

confidence: 99%

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The non-acoustic signatures of underwater vehicles

Slimming,

Beniwal,

Devrelis

et al. 2023

Ocean Sensing and Monitoring XV

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Submersible vehicles, such as Uncrewed Underwater Vehicles (UUVs), can be lost underwater and it is desirable to locate them before they go missing or collide with other vehicles. These objects generate inherent signatures when they move in the ocean. With a better understanding of these signatures, more information regarding the motion of underwater vehicles can be inferred using LiDAR technology. In this paper, the authors review existing literature on various non-acoustic signatures of a submerged body, namely, the electromagnetic, biological and thermal signatures, turbulent wake patterns, internal waves and vortex structures. The authors discuss how these signatures evolve both spatially and temporally. Furthermore, the review investigates how environmental and operational parameters such as the stratification of the medium, vehicle speed, shape and depth affect the non-acoustic signatures. Underwater vehicles operating at low speeds and large depths have bioluminescent, Kelvin wake and Bernoulli hump signatures that are difficult to detect on the surface. Thermal signatures, vortex wakes and far wakes are only likely to be detected at the vehicle’s depth. This is primarily due to the ocean stratification which suppresses the vertical motion of underwater turbulent signatures. Thermal signatures appear to be most likely to be detected. The study concludes that relying on a single signature to detect submersibles is not advisable and future methods for underwater vehicle detection should use multiple sensors to detect complementary signatures.

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Section: Internal Wavesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The non-acoustic signatures of underwater vehicles

Slimming,

Beniwal,

Devrelis

et al. 2023

Ocean Sensing and Monitoring XV

View full text Add to dashboard Cite

show abstract

“…The literature [ 17 ] proposes that the submarine wake evolution can be divided into three periods, and the characteristics of the wake change randomly in different periods. The literature [ 18 ] investigated the wake characteristics of a model submarine navigating in a uniform linearly stratified fluid and demonstrated that the stratified fluid affects the formation and evolution of the submarine wake. In the literature [ 19 ], the wake vortex evolution was studied by particle image velocimetry and the change process of the wake vortex structure was discussed.…”

Section: Related Workmentioning

confidence: 99%

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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