Fluid–structure interaction during the impact of a cylindrical shell on a thin layer of water

Хабахпашева, Т. И.

doi:10.1016/j.jfluidstructs.2008.09.004

Cited by 23 publications

(18 citation statements)

References 15 publications

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“…The matching conditions (2.3) were used in the past in different forms in some earlier studies [2,3,6,18,19]. At the end of the impact stage, t = t * , the derivativeċ − (t) tends to zero and the jet at the trailing edge disappears.…”

Section: Governing Equationsmentioning

confidence: 99%

Oblique impact of a smooth body on a thin layer of inviscid liquid

Хабахпашева

Korobkin

2013

Proc. R. Soc. A.

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The two-dimensional motion of a rigid body with a smooth surface is studied during its oblique impact on a liquid layer. The problem is coupled: the three degrees of freedom of the moving body are determined together with the liquid flow and the hydrodynamic pressure along the wetted part of the body surface. The impact process is divided into two temporal stages. During the first stage, the wetted region expands at a high speed with jetting flows at both ends of the wetted region. In the second stage, the free surface of the liquid is allowed to separate from the body surface. The position of the separation point is determined with the help of the Brillouin-Villat condition. Calculations are performed for elliptic cylinders of different masses and with different orientations and speeds before the impact. The horizontal and vertical displacements of the body, as well as its angle of rotation and corresponding speeds are investigated. The model developed remains valid until the body either touches the bottom of the liquid or rebounds from the liquid.

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Section: Governing Equationsmentioning

confidence: 99%

Oblique impact of a smooth body on a thin layer of inviscid liquid

Хабахпашева

Korobkin

2013

Proc. R. Soc. A.

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“…In [12] the Korobkin method [1] was applied to the solution of the problem of impact of an elastic cylindrical shell on the free surface of a fluid layer. The elastic shell vibrations were described using the normal mode method.…”

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“…It was noted that the elastic shell strains cease to depend on the depth as the depth of the fluid layer increases. Moreover, in [12] the elongations in the cylindrical shells during impact on a fluid obtained in the thin-layer approximation were compared with the experimental results [13] and the results obtained in [14] for infinitely deep fluid in the Wagner approximation. In [14] the normal mode method was used to determine the shell vibrations.…”

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confidence: 99%

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Impact of an elastic spherical shell on a thin fluid layer

Хабахпашева

2015

Fluid Dyn

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The axisymmetric problem of the impact of a spherical shell on a thin layer of an ideal incompressible fluid is considered. The strains of the spherical shell are described by means of the normal mode method, a decomposition of the fluid flow zone onto subzones proposed in [1] being used for the hydrodynamic analysis and determination of the radius of the wetted surface. The connected problem of hydroelasticity is reduced to an evolutionary system of differential equations and calculations of the features of impact are carried for various parameters of the problem. It is shown that vibrations corresponding to the higher modes develop in the lower part of the shell during the impact on the fluid surface. This is in agreement with experiments and proves the inconsistency of the models in which a few number of modes are taken into account. The thinner is the fluid layer, the higher are the hydrodynamic loads and the amplitude of elastic vibrations of the shell during the impact. Keywords: interaction between body and fluid, impact on a thin fluid layer, method of asymptotic matched expansions, spherical shell.The problem of impact of a body on a fluid surface became topical in thirties at the last century when the first hydroplanes were begun to be constructed. The studies by von Kármán [2] and Wagner [3] were pioneered in this field. The fluid was assumed to be ideal, incompressible, and infinitely deep, while the body shape to be almost parallel to the fluid surface. In the first theoretical investigation carried out by von Kármán in 1929, the pressure on the rigid bottom of the pontoon during hydroplane landing was determined, the contact zone being determined by simple intersection of the domains occupied by the submerged body and the undisturbed fluid. In this case the so-called "flat disc approximation" was used so that the kinematic and dynamic conditions on the body and free surfaces were projected to the level of the undisturbed fluid surface.In 1932 Wagner extended the von Kármán model by taking the rise of the free fluid surface during impact into account. The rise of the free surface at the conjugation point (point of contact between the free fluid surface and the body) was assumed to coincide with the location of the body surface and the boundary conditions were referred to the horizontal line passing through the conjugation point. Afterwards, the Wagner approach was used and adapted to various problems of the impact of both rigid and elastic bodies on a fluid. In [4,5] these investigations were reviewed in detail.Practically at the same time, similar investigations were carried out in TsAGI [6-10]; however, in these studies the impact on a body already floating on the fluid surface was considered and the stage of impact with expending contact zone was neglected. But this stage is of great importance since the load on the body is proportional to the contact zone extension rate and, as compared with the stage of submergence in which the body is completely wetted, the hydrodynamic load on the body is high...

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“…After that, a lot of studies were conducted to predict the hydrodynamic load both for two-dimensional rigid circular cylinders and elastic cylinders. 2,3 Even nowadays, only a few studies on the water entry of three-dimensional cylinders are reported for the complexity of the problems. As the initial inclined angle is introduced, the phenomenon of the water entry of the cylinders will become more complicated, which is very different from that related to a two-dimensional cylinder.…”

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Evolution of three-dimensional cavitation following water entry of an inclined cylinder

Wei

Shi

2012

Theoretical and Applied Mechanics Letters

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The water entry of an inclined cylinder is firstly studied experimentally for low Froude number. The cylinder is 50 mm in diameter and 200 mm in length, with a moderate length to diameter ratio. As it is submerged below the water surface, the cavity is fully three-dimensional. Due to the rotation of the cylinder caused by the initial inclined impact, the cavity evolution is quite complicated and a new phenomenon is revealed. The cylinder moves along a curved trajectory in water, which greatly affects the evolution of the cavities. The cavity breaks up into two sub-cavities, and finally collapses because of hydrostatic pressure.The water entry problems of two-dimensional cylinders have been widely studied for a very long time. A typical result of the experimental images was provided by Greenhow and Lin. 1 In their experiment, the flow could be approximated as a two-dimensional one. After that, a lot of studies were conducted to predict the hydrodynamic load both for two-dimensional rigid circular cylinders and elastic cylinders. 2,3 Even nowadays, only a few studies on the water entry of three-dimensional cylinders are reported for the complexity of the problems. As the initial inclined angle is introduced, the phenomenon of the water entry of the cylinders will become more complicated, which is very different from that related to a two-dimensional cylinder. 1 For relatively short cylinders, the length to diameter ratio is small. As the cylinder touches the water surface, the initial impact will cause the cylinder to rotate with relatively larger angular velocity compared with the entry of an inclined "rod" described by Ueda et al. 4 The rotation will obviously influence the evolution of the cavities. For some special inclined angles and length to diameter ratios, the cavity breaks up into two parts. The trajectory of the cylinder in water is curved. These new phenomena will be revealed and discussed as follows.The schematic illustration of the experimental apparatus is shown in Fig. 1. The Polypropylene cylinder used in the experiment has a density of ρ = 902 kg/m 3 , diameter of D = 50 mm, length of L = 200 mm, thus the length to diameter ratio is L/D = 4. The contact angle of the cylinder surface is about 98 • . The cylinder is cleaned by ethanol only, and no other surface treatment is applied. The initial gravity center of the cylinder is 2.0 m high above the water surface. The impact tank has a dimension of 1.35 m × 1.35 m × 1.35 m, and the water depth is 1.0 m. As the cylinder is released freely by a clamp, it impacts the water with an initial velocity of V 0 = 6.10 m/s and an inclined angle a) Corresponding author. Email: weimuru@163.com. Fig. 1. Schematic illustration of the experimental apparatus.of 60 • . The Froude number is F r = V 0 / √ gD = 8.72. As the back lighting, foreground lighting and lateral lighting are set in their best conditions (Fig. 1), the high speed digital camera (FASTCAM-APX RS) with a 105 mm Nikon lens is used to study the water entry phenomenon. The camera is arranged at the same...

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Fluid–structure interaction during the impact of a cylindrical shell on a thin layer of water

Cited by 23 publications

References 15 publications

Oblique impact of a smooth body on a thin layer of inviscid liquid

Oblique impact of a smooth body on a thin layer of inviscid liquid

Impact of an elastic spherical shell on a thin fluid layer

Evolution of three-dimensional cavitation following water entry of an inclined cylinder

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