Phase and amplitude discrepancies in the surface wave due to a wedge-ended hull form

Standing, R G

doi:10.1017/s002211207400084x

Cited by 9 publications

(6 citation statements)

References 5 publications

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“…Thus, for many practical purposes, notably for our purpose and for concept and preliminary design, thin-ship theory is a reasonable and useful approximation, as well documented in the literature, e.g. [5][6][7][8][9][10]. The ratios Z thin b /Z data b and X thin b / X data b are also listed below Figure 23 and the related foregoing table, and the bow waves shown in Fig.…”

Section: Bow Waves Generated By Wedge-shaped Ship Bowsmentioning

confidence: 81%

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Thin-ship theory and influence of rake and flare

Noblesse¹,

Delhommeau²,

Kim

et al. 2008

J Eng Math

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The basic computational task of the thin-ship theory of free-surface potential flow about a ship that advances at constant speed along a straight path in calm water, of large depth and lateral extent, is considered. Specifically, a straightforward method for evaluating the pressure and the wave profile at a ship hull (the wave drag, hydrodynamic lift and pitch moment, and sinkage and trim are also considered) in accordance with Michell's thin-ship theory is given. A main ingredient of this method is a simple analytical approximation to the local-flow component in the expression for the Green function (associated with the classical Michell-Kelvin linearized freesurface boundary condition) of thin-ship theory. This practical Green function is used to evaluate and analyze steady flow about a four-parameter family of ship bows with rake and flare. In particular, the variations of the bow-wave height and location with respect to the draft-based Froude number, the entrance angles at the top and bottom waterlines, and the rake angle are explored via a systematic parametric study. This parametric study provides estimates-immediately useful for design-of the influence of rake and flare on the height and the location of a ship bow wave, and shows that rake and flare effects can be significant, especially at low Froude numbers. 123 50 F. Noblesse et al. δ = 45°, α = 15°, α' = 5°δ = -45°, α = 5°, α' = 15°Fig.

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Section: Bow Waves Generated By Wedge-shaped Ship Bowsmentioning

confidence: 81%

“…This basic and classical task-considered in numerous studies, e.g. [5][6][7][8][9][10]-is revisited here.…”

Section: Michell's Thin-ship Approximationmentioning

confidence: 99%

Thin-ship theory and influence of rake and flare

Noblesse¹,

Delhommeau²,

Kim

et al. 2008

J Eng Math

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“…The thin-ship theory has been widely used (e.g. Standing 1974;Noblesse & Dagan 1976). A number of alternative slender-ship and 2d+t approximations have been proposed and used (Tuck 1966;Ogilvie 1967;Chapman 1976;Noblesse 1983;Ç alişal & Chan 1989;Fontaine, Faltinsen & Cointe 2000).…”

Section: Introductionmentioning

confidence: 99%

Simple analytical relations for ship bow waves

Noblesse¹,

Delhommeau

Guilbaud

et al. 2008

J. Fluid Mech.

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Simple analytical relations for the bow wave generated by a ship in steady motion are given. Specifically, simple expressions that define the height of a ship bow wave, the distance between the ship stem and the crest of the bow wave, the rise of water at the stem, and the bow wave profile, explicitly and without calculations, in terms of the ship speed, draught, and waterline entrance angle, are given. Another result is a simple criterion that predicts, also directly and without calculations, when a ship in steady motion cannot generate a steady bow wave. This unsteady-flow criterion predicts that a ship with a sufficiently fine waterline, specifically with waterline entrance angle 2αE smaller than approximately 25°, may generate a steady bow wave at any speed. However, a ship with a fuller waterline (25°<2αE) can only generate a steady bow wave if the ship speed is higher than a critical speed, defined in terms of αE by a simple relation. No alternative criterion for predicting when a ship in steady motion does not generate a steady bow wave appears to exist. A simple expression for the height of an unsteady ship bow wave is also given. In spite of their remarkable simplicity, the relations for ship bow waves obtained in the study (using only rudimentary physical and mathematical considerations) are consistent with experimental measurements for a number of hull forms having non-bulbous wedge-shaped bows with small flare angle, and with the authors' measurements and observations for a rectangular flat plate towed at a yaw angle.

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“…Values of α E , T and F T can be found in table 1. The theoretical curve is from Noblesse et al (2006), and the data from tests with three-dimensional models (extracted from figure 2 of Noblesse et al 2006) are from Ogilvie (1972), Standing (1974) and Waniewski, Brennen & Raichlen (2002). bows) and the present data from figure 15 are plotted.…”

Section: Geometrical Parameters 331 Contact Linementioning

confidence: 99%

An experimental investigation of divergent bow waves simulated by a two-dimensional plus temporal wave marker technique

2009

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Divergent ship bow waves were simulated experimentally with a two-dimensional wavemaker that employs a flexible wave board. The wavemaker was programmed so that the wave board created a time sequence of shapes that simulated the line of intersection between one side of the hull of a slender ship model moving at constant speed and an imaginary vertical plane oriented normal to the ship model track. The time history of the water surface shape was measured with a cinematic laser-induced fluorescence technique for eight Froude numbers (FD = U/, where U is the forward speed of the equivalent three-dimensional ship model, g the acceleration of gravity and D the ship model draft). The waves produced ranged from small-amplitude non-breaking waves at the lowest Froude numbers to plunging breakers at the highest Froude numbers. These waves are strongly forced and at the higher Froude numbers begin breaking before leaving the wave board. The time histories of various geometric characteristics of the water surface shape including the hull contact line, the wave crest, the plunging jet and the splash zone, which is here defined as both the turbulent zone on the front face of the wave in the spilling breakers and the turbulent zone generated ahead of the jet impact point in the plunging breakers, were measured. The phase speed of the primary wave generated during each run ranged from 2.56Uwl (where Uwl is the maximum speed of the wave board at the undisturbed water level in the tank) at the lowest Froude number to about 1.7Uwl at the three highest Froude numbers. The maximum heights of the primary wave, the contact point on the wavemaker and the splash zone increased in a nearly linear fashion with increasing FD. In the cases with plunging jets, the jet tip trajectory was parabolic with a vertical acceleration ranging from 0.6g at FD = 1.467 to 0.8g at FD = 1.817 (the highest Froude number).

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Phase and amplitude discrepancies in the surface wave due to a wedge-ended hull form

Cited by 9 publications

References 5 publications

Thin-ship theory and influence of rake and flare

Thin-ship theory and influence of rake and flare

Simple analytical relations for ship bow waves

An experimental investigation of divergent bow waves simulated by a two-dimensional plus temporal wave marker technique

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