Wave forces on three-dimensional floating bodies with small forward speed

Nossen, Jan; Grue, John; Palm, Enok

doi:10.1017/s002211209100006x

Cited by 86 publications

(54 citation statements)

References 9 publications

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“…The resulting Green function is simpler and more efficient compared to the conventional approach (Bessho, 1977). Nossen et al (1991), on the other hand, extended the boundary integral to include the near-field free surface to account for the modification of the steady flow around the body. The use of a Green function that satisfies the free surface boundary condition can lead to the so-called irregular frequencies, at which the matrix equation becomes singular.…”

Section: Potential Flow With Vessel Forward Speedmentioning

confidence: 99%

Hydroelasticity of marine vessels advancing in a seaway

Das

Cheung

2012

Journal of Fluids and Structures

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Section: Potential Flow With Vessel Forward Speedmentioning

confidence: 99%

Hydroelasticity of marine vessels advancing in a seaway

Das

Cheung

2012

Journal of Fluids and Structures

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“…Only horizontal components of the steady second order forces will be considered here and the so called far-field expression for these forces is [26]:…”

Section: First Order Loadsmentioning

confidence: 99%

“…Another interesting phenomenon concerning the wave-current-floating body interactions is the secularity (unphysical growth of the solution far away from the body) of the additional perturbation by τ (35). In spite of the recognized secularity of the solution the perturbation by τ is a common approach to treat this problem [26]. Only recently [25,5] it was numerically shown that both solutions (secular and non-secular) are the same as far as the global forces are concerned.…”

mentioning

confidence: 99%

Semi-Analytical Methods for Different Problems of Diffraction-Radiation by Vertical Circular Cylinders

Malenica¹

2012

International Journal of Ocean System Engineering

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As in the other fields of mechanics, analytical methods represent an important analysis tool in marine hydrodynamics. The analytical approach is interesting for different reasons : it gives reference results for numerical codes verification, it gives physical insight into some complicated problems, it can be used as a simplified predesign tool, etc. This approach is of course limited to some simplified geometries (cylinders, spheres, ...), and only the case of one or more cylinders, truncated or not, will be considered here. Presented methods are basically eigenfunction expansions whose complexity depends on the boundary conditions. The hydrodynamic boundary value problem (BVP) is formulated within the usual assumptions of potential flow and is additionally simplified by the perturbation method. By using this approach, the highly nonlinear problem decomposes into its linear part and the higher order (second, third, ...) corrections. Also, periodicity is assumed so that the time dependence can be factorized i.e. the frequency domain formulation is adopted. As far as free surface flows are concerned, only cases without or with small forward speed are sufficiently simple to be solved semi-analytically. The problem of the floating body advancing in waves with arbitrary forward speed is far more complicated. These remarks are also valid for the general numerical methods where the case of arbitrary forward speed, even linearized, is still too difficult from numerical point of view, and "it is fair to say that there exists at present no general practical numerical method for the wave resistance problem" [9], and even less for the general seakeeping problem. We note also that, in the case of bluff bodies like cylinders, the assumptions of the potential flow are justified only if the forward speed is less than the product of wave amplitude with wave frequency.

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“…The standard potential flow theory assumes that the motion is relatively small and harmonic in time [2,3].…”

Section: Introductionmentioning

confidence: 99%

A semi-analytical computation of the Kelvin kernel for potential flows with a free surface

D’Elı́a¹,

Battaglia²,

Storti³

2011

Comput. Appl. Math.

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Abstract.A semi-analytical computation of the three dimensional Green function for seakeeping flow problems is proposed. A potential flow model is assumed with an harmonic dependence on time and a linearized free surface boundary condition. The multiplicative Green function is expressed as the product of a time part and a spatial one. The spatial part is known as the Kelvin kernel, which is the sum of two Rankine sources and a wave-like kernel, being the last one written using the Haskind-Havelock representation. Numerical efficiency is improved by an analytical integration of the two Rankine kernels and the use of a singularity subtractive technique for the Haskind-Havelock integral, where a globally adaptive quadrature is performed for the regular part and an analytic integration is used for the singular one. The proposed computation is employed in a low order panel method with flat triangular elements. As a numerical example, an oscillating floating unit hemisphere in heave and surge modes is considered, where analytical and semi-analytical solutions are taken as a reference.Mathematical subject classification: Primary: 33F05; Secondary: 65N38.

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Wave forces on three-dimensional floating bodies with small forward speed

Cited by 86 publications

References 9 publications

Hydroelasticity of marine vessels advancing in a seaway

Hydroelasticity of marine vessels advancing in a seaway

Semi-Analytical Methods for Different Problems of Diffraction-Radiation by Vertical Circular Cylinders

A semi-analytical computation of the Kelvin kernel for potential flows with a free surface

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