The effect of rigid-body motions on the whipping response of a ship hull subjected to an underwater bubble

A numerical simulation has been carried out to examine the response of steel plates with different arrangement of stiffeners and subjected to noncontact underwater explosion (UNDEX) with different shock loads. Numerical analysis of the underwater explosion phenomena is implemented in the nonlinear finite element code ABAQUS/Explicit. The aim of this work is to enhance the dynamic response to resist UNDEX. Special emphasis is focused on the evolution of mid-point displacements. Further investigations have been performed to study the effects of including material damping and the rate-dependant material properties at different shock loads. The results indicate that stiffeners configurations and shock loads affect greatly the overall performance of steel plates and sensitive to the materials data. Also, the numerical results can be used to obtain design guidelines of floating structures to enhance resistance of underwater shock damage, since explosive tests are costly and dangerous.

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“…In case of TNT charge, the maximum bubble radii of explosive gas, max , and first pulsation periods, , are expressed as [19]:…”

Section: The Undex Loadingmentioning

confidence: 99%

Numerical Simulation and Response of Stiffened Plates Subjected to Noncontact Underwater Explosion

Fathallah

Tong

et al. 2014

Advances in Materials Science and Engineering

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“…Previous studies on the interaction between the bubble and nearby structures below the free surface have paid more attention to the physical phenomena in some specific engineering scenarios, such as the rise and fall of the free surface (Liu et al 2016;Zhang et al 2017), interaction between the bubble and a vessel (Klaseboer, Khoo & Hung 2005b;Zhang & Zong 2011;Zhang, Zong & Zhang 2014), and deformation of the floating structure caused by bubble pulsations (Klaseboer et al 2005a;Zong et al 2015). Some parametric analysis of the bubble collapse has been conducted: Kiyama et al (2021) and Tagawa & Peters (2018) used the method of images to develop a theoretical model for determining the jet direction when a cavity is near a corner; Molefe & Peters (2019) studied the jet direction when a cavity is within rectangular and triangular channels; Andrews, Rivas & Peters (2020) predicted the jet direction near a slot with the boundary integral method (BIM); and Brujan conducted comprehensive studies on the corner of two or three rigid boundaries (Brujan et al 2018;Brujan, Hiroyuki & Toshiyuki 2019;Brujan et al 2022).…”

Section: Introductionmentioning

confidence: 99%

“…2016; Zhang et al. 2017), interaction between the bubble and a vessel (Klaseboer, Khoo & Hung 2005 b ; Zhang & Zong 2011; Zhang, Zong & Zhang 2014), and deformation of the floating structure caused by bubble pulsations (Klaseboer et al. 2005 a ; Zong et al.…”

Section: Introductionmentioning

confidence: 99%

Vertically neutral collapse of a pulsating bubble at the corner of a free surface and a rigid wall

Zhang

Cui

et al. 2023

J. Fluid Mech.

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Vertically neutral collapse of a pulsating bubble occurs when the boundaries above or below the bubble balance the buoyancy effect over a pulsation. In this study, the vertically neutral collapse of a bubble near a vertical rigid wall below the free surface is investigated. The boundary integral method (BIM) is employed to model the bubble dynamics with an open-domain free surface. Moreover, this method is validated against several buoyant bubble experiments. Bubble dynamics in such conditions are associated with three dimensionless parameters: the bubble-free surface distance $\gamma _{{f}}$ , bubble–wall distance $\gamma _{{w}}$ and buoyancy parameter $\delta$ . We derive the Kelvin impulse of a spherical bubble and the algebraic relationship for vertically neutral collapse, which proves to be accurate for predicting vertically neutral collapse when the bubble is relatively far from the boundaries. Four patterns of the vertically neutral collapse of the bubble for different $\gamma _{{w}}$ and $\gamma _{{f}}$ are identified: (i) formally downward jet; (ii) annular collapse; (iii) horizontal jet; and (iv) weak jet. Despite the downward jet shape, the ‘formally downward jet’ is in the vertically neutral collapse state in terms of the profile of toroidal bubbles and the orientation of local high-pressure zones around the bubble at jet impact. A bulge with a high curvature above the bubble in the ‘annular collapse’ pattern is formed during bubble collapse under two local high-pressure zones at the left and right extremities of the bubble. The ‘horizontal jet’ pattern has the greatest potential to attack the wall, and the power laws of the moment of the jet impact, jet velocity and bubble displacement with respect to the theoretical Kelvin impulse are discussed. In particular, we quantitatively illustrate the role of the free surface on bubble migration towards the wall through the variational power-law exponents of the bubble displacement with respect to $\gamma _{{w}}$ .

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“…During this phase, the compressibility of the fluid must be considered to simulate the propagation of the shockwave and the radiation effects of the structure. The bubble load with long period can induce the overall whipping responses and the rigid motion that threaten the global strength [Zhang and Zong (2011); Stettler (1995); Hicks (1986); Vernon (1986); Wilkerson (1985)]. For this problem, BEM based on potential flow theory is one of the most widely used methods, because the viscosity and the compressibility of the fluid are neglectable.…”

Section: Introductionmentioning

confidence: 99%

“…For this problem, BEM based on potential flow theory is one of the most widely used methods, because the viscosity and the compressibility of the fluid are neglectable. Zhang et al [Zhang and Zong (2011)] studied the dynamic responses of a surface ship subjected to underwater explosion bubble, and found that rigid motions cannot be ignored for shorter/wider hulls. Lu et al [Lu, He and Wu (2000)] presented a completely coupled method for the hydroelastic interaction during the impact of a structure with water.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Response of Floating Body Subjected to Underwater Explosion Bubble and Generated Waves with 2D Numerical Model

Tian¹,

Liu²,

Wang³

et al. 2019

Computer Modeling in Engineering &Amp; Sciences

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The low frequency load of an underwater explosion bubble and the generated waves can cause significant rigid motion of a ship that threaten its stability. In order to study the fluid-structure interaction qualitatively, a two-dimensional underwater explosion bubble dynamics model, based on the potential flow theory, is established with a double-vortex model for the doubly connected bubble dynamics simulation, and the bubble shows similar dynamics to that in 3-dimensional domain. A fully nonlinear fluid-structure interaction model is established considering the rigid motion of the floating body using the mode-decomposition method. Convergence test of the model is implemented by simulating the free rolling motion of a floating body in still water. Through the simulation of the interaction of the underwater explosion bubble, the generated waves and the floating body based on the presented model, the influences of the buoyancy parameter and the distance parameter are discussed. It is found that the impact loads on floating body caused by underwater explosion bubble near the free surface can be divided into 3 components: bubble pulsation, jet impact, and slamming load of the generated waves, and the intensity of each component changes nonlinearly with the buoyance parameter. The bubble pulsation load decays with the increase in the horizontal distance. However, the impact load from the generated waves is not monotonous to distance. It increases with the distance within a particular distance threshold, but decays thereafter.

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The effect of rigid-body motions on the whipping response of a ship hull subjected to an underwater bubble

Cited by 40 publications

References 13 publications

Numerical Simulation and Response of Stiffened Plates Subjected to Noncontact Underwater Explosion

Numerical Simulation and Response of Stiffened Plates Subjected to Noncontact Underwater Explosion

Vertically neutral collapse of a pulsating bubble at the corner of a free surface and a rigid wall

Dynamic Response of Floating Body Subjected to Underwater Explosion Bubble and Generated Waves with 2D Numerical Model

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