Numerical analysis of added resistance on an icebreaker in regular waves

2020 ◽  
Author(s):  
Chao Chen ◽  
Ya-dong Liu ◽  
Yan-ping He ◽  
Xing-yu Li
Keyword(s):  
Numerical Analysis ◽  
Added Resistance ◽  
Regular Waves

The Performance of Sailing Yachts in Oblique Seas

1974 ◽  
Vol 11 (04) ◽  
pp. 383-392
Author(s):  
David R. Pedrick
Keyword(s):  
Wave Length ◽  
Added Resistance ◽  
Regular Waves ◽  
Sea State ◽  
Hull Form ◽  
Rough Water ◽  
Rational Procedure ◽  
The Difference ◽  
Relationship Of ◽  
The Relationship

The difference in the effects of rough water on similar sailing yachts has been one of the intriguing puzzles that sailors, designers, and researchers have long tried to understand. It is not uncommon for two yachts of equal performance in smooth-sea conditions to have their speed or pointing ability reduced by different amounts when encountering waves. To investigate the causes of such behavior, it is important to have a rational procedure to analyze how changes in hull form, weight distribution, rig, and other design features affect the speed and motions of sailing yachts. This paper discusses the relationship of wind to rough water and of motions and added resistance to wave length and height. It then describes a procedure to predict motions, sailing speed, and speed-made-good to windward in realistic windward sailing conditions. The procedure utilizes results of heeled and yawed model tests of 12-metre yachts in oblique regular waves to predict performance in a Pierson-Moskowitz sea state corresponding closely to the equilibrium true wind speed.

The Effect of Pitch Gyradius on Added Resistance of Yacht Hulls

1991 ◽  
Author(s):  
James F. Moran
Keyword(s):  
Water Resistance ◽  
Wave Spectrum ◽  
Response Amplitude ◽  
Added Resistance ◽  
Regular Waves ◽  
Low Frequencies ◽  
Irregular Wave ◽  
Wave Data ◽  
The Difference ◽  
Response Amplitude Operators

The purpose of this investigation was to determine the effect of pitch gyradius on added resistance of yacht hulls. Tank testing of a model yacht in head seas was performed in the Webb Robinson Model Basin. The model was tested in regular waves at two speeds and five variations of gyradius. The model was also evaluated in irregular seas of the Pierson-Moskowitz spectrum at various speeds with two gyradii. Response Amplitude Operators were developed from the regular wave data and comparisons made. The irregular wave data were analyzed for the effect of speed on the difference in added resistance between the maximum and minimum gyradius settings. Several conclusions were arrived at after analyzing the data. The Response Amplitude Operaters shift as the gyradius changes. In regular waves, at low frequencies of encounter, a lower, gyradius resulted in less added frequencies of encounter in regular waves, this trend reverses itself and the higher gyradii result in reduced added resistance. However, at higher frequencies of encounter in regular waves, this trend reverses, reverses itself in reduced added resistance. The peaks of the RAO curves shift to higher frequencies at higher gyradii. It was also concluded that at the higher speed, Froude Number of 0.3, the added resistance was lower relative to the still-water resistance for each gyradius tested. The irregular wave testing revealed the effect of the lower frequencies dominating the irregular wave spectrum. The minimum gyradius, in irregular seas showed less added resistance than the maximum gyradius. In addition, the irregular wave testing verified, the reduction of added resistance, relative to still-water resistance, at increasing speeds for both the minimum and maximum gyradii.

scholarly journals Verification and Validation of a Methodology to Numerically Generate Waves Using Transient Discrete Data as Prescribed Velocity Boundary Condition

2021 ◽  
Vol 9 (8) ◽  
pp. 896
Author(s):  
Rafael P. Maciel ◽  
Cristiano Fragassa ◽  
Bianca N. Machado ◽  
Luiz A. O. Rocha ◽  
Elizaldo D. dos Santos ◽  
...  
Keyword(s):  
Boundary Condition ◽  
Numerical Analysis ◽  
Laboratory Experiment ◽  
Ocean Waves ◽  
Discrete Data ◽  
Multiphase Model ◽  
Computational Domain ◽  
Regular Waves ◽  
Ansys Fluent ◽  
Wave Channel

This work presents a two-dimensional numerical analysis of a wave channel and a oscillating water column (OWC) device. The main goal is to validate a methodology which uses transient velocity data as a means to impose velocity boundary condition for the generation of numerical waves. To achieve this, a numerical wave channel was simulated using regular waves with the same parameters as those used in a laboratory experiment. First, these waves were imposed as prescribed velocity boundary condition and compared with the analytical solution; then, the OWC device was inserted into the computational domain, aiming to validate this methodology. For the numerical analysis, computational fluid dynamics ANSYS Fluent software was employed, and to tackle with water–air interaction, the nonlinear multiphase model volume of fluid (VOF) was applied. Although the results obtained through the use of discrete data as velocity boundary condition presented a little disparity; in general, they showed a good agreement with laboratory experiment results. Since many studies use regular waves, there is a lack of analysis with ocean waves realistic data; thus, the proposed methodology stands out for its capacity of using realistic sea state data in numerical simulations regarding wave energy converters (WECs).

Uncertainty analysis for measurement of added resistance in short regular waves: Its application and evaluation

2020 ◽  
Vol 216 ◽  
pp. 107823
Author(s):  
Naoto Sogihara ◽  
Masaru Tsujimoto ◽  
Ryohei Fukasawa ◽  
Tatsuya Hamada
Keyword(s):  
Uncertainty Analysis ◽  
Added Resistance ◽  
Regular Waves

Numerical Analysis of Added Resistance on Ship in Parametric Roll Motions

2016 ◽  
Author(s):  
Jae-Hoon Lee ◽  
Yonghwan Kim ◽  
Min-Guk Seo
Keyword(s):  
Near Field ◽  
Three Dimensional ◽  
Field Method ◽  
Roll Motion ◽  
Added Resistance ◽  
Regular Waves ◽  
Nonlinear Formulation ◽  
Parametric Roll ◽  
Weakly Nonlinear ◽  
Rankine Panel Method

In the present study, the added resistance of a containership in parametric roll motion is investigated. The numerical simulation is carried out using a three dimensional Rankine panel method along with the weakly nonlinear formulation. The added resistance is evaluated by a near-field method, namely, the direct integration of the 2nd-order pressure on a body surface. To calculate the component resulting from the large-amplitude roll motion, the higher-order restoring and Froude-Krylov forces on wetted hull surfaces are taken into account. With or without parametric roll in regular waves, the components of added resistance classified with respect to integral terms are compared to figure out the important of each term. Through the investigation, the correlation between the added resistance and parametric roll is derived from coupling and decoupling the components of roll motion and vertical motions.

Numerical Analysis on Added Resistance of Ship by 3-D Green Function Method

2006 ◽  
Author(s):  
Yoshiyuki Inoue ◽  
N. M. Golam Zakaria
Keyword(s):  
Experimental Data ◽  
Numerical Analysis ◽  
Green Function ◽  
Function Method ◽  
Numerical Results ◽  
Numerical Code ◽  
Added Resistance ◽  
Green Function Method ◽  
Total Potential ◽  
Motion Responses

This paper deals with the numerical analysis on added resistance of a ship by 3-D Green Function Method. Linear potential theory has been used to describe the fluid motion and 3-D sink-source technique with forward speed has been applied to determine hydrodynamic forces for surface ship advancing in waves at constant speed. After solving the motion equation in frequency domain, radiation potential due to motion responses have been calculated to obtain the total potential of the flow field. Then, total potential and its derivatives have been obtained to assess the added resistance in waves by near field approach. To show the validity of the numerical code, the present numerical results for motion responses and wave loads on ships have been compared with experimental data as well as some numerical results by different approaches. Then the added resistances given by present numerical calculation by 3-D Green Function have been compared with some classical 2-D methods as well as experimental data for Series 60 ships. Finally the present numerical calculations have been applied for fuller form slow speed vessel where the classical 2-D methods usually fails to give good results due to their inherent limitations. The numerical results suggest that better agreement have been achieved in many cases using present full 3-D Green Function method.

Approximation of the added resistance of ships with small draft or in ballast condition by empirical formula

2017 ◽  
Vol 233 (1) ◽  
pp. 27-40 ◽  
Author(s):  
Shukui Liu ◽  
Apostolos Papanikolaou
Keyword(s):  
Parametric Study ◽  
Empirical Formula ◽  
Power Estimation ◽  
Design Stage ◽  
Added Resistance ◽  
Regular Waves ◽  
Early Design Stage ◽  
Cruise Ships ◽  
New Formula ◽  
The Impact

An attempt was made to extend and further tune the existing formula for approximating the added resistance in head seas to cover a wider range of speed and to account the impact of loading conditions; a new parameter based on B/ T was introduced after conducting extensive parametric study to capture the influence of draft on the added resistance; the trim effect has also been investigated; Furthermore, the draft effect on the added resistance due to diffraction is further tuned and simplified. The derived formula uses only a few input, including only some ship dimensions to yield an estimation of the added resistance of ships in regular waves. Numerical results show that the added resistance of various ships in head seas at low speeds, as well as the added resistance of tankers in ballast condition and cruise ships, can be properly captured by the new formula. Hence, it meets the demand of fast examination of the minimum power; it can also be used in the early design stage of a ship for power estimation.

scholarly journals Исследования особенностей снижения продольной качки и дополнительного сопротивления судна с крыльевыми устройствами

2020 ◽  
Author(s):  
Z.M. Htet
Keyword(s):  
Energy Saving ◽  
Orbital Motion ◽  
Calculated Data ◽  
Ship Motions ◽  
Added Resistance ◽  
Regular Waves ◽  
Kinematic Parameters ◽  
Coupled Equations ◽  
Added Resistance In Waves ◽  
Oscillating Foil

В данной статье на основе предложенного расчета качки судна с энергосберегающими крыльевыми устройствами производится оценка мореходности и ходкости такого судна и возможности целенаправленного уменьшения амплитуд качки и снижения дополнительного сопротивления на волнении. Продольная качка судна заданного типа, обводов и размерений при наличии крыльевых элементов на заданном регулярном волнении рассчитывается с привлечением совместных уравнений вертикально-килевой качки с учетом демпфирования и инерции крыльевых устройств. При этом используется теория Теодорсена колеблющегося профиля и разложение нестационарных коэффициентов подъемной силы и момента по кинематическим параметрам при комбинировании вертикальных и угловых колебаний, и, в общем случае, в условиях воздействия орбитального движения жидкости. Для оценки дополнительного сопротивления используется теория Герритсмы и Бекельмана. В ходе расчетов демонстрируется влияние на дополнительное сопротивление удлинения и площади энергосберегающих крыльев, а также возможности снижения дополнительного сопротивления при совместном использовании носового и кормового крыльев по сравнению со случаем использования только одного (носового или кормового) крыла. Полученные расчетные данные позволяют получить представление о механизме влияния энергосберегающих крыльев на умерение амплитуд качки и снижение дополнительного сопротивления на волнении.In this article on the basis of the method for calculation of longitudinal motions of a ship with energy-saving wing devices proposed there is made an estimation of seaworthiness and seagoing capacity of such a ship and also of a possibility of directed decrease of ship motions amplitudes and added resistance in waves. The longitudinal motions of a ship of a given type, configuration and dimensions, in presence of wing elements, and in given regular waves is calculated with use of coupled equations of heave and pitch motions with account of damping and inertia of wing devices. Used therewith is Theodorsen theory of oscillating foil and expansion of lift and moment coefficients with respect to kinematic parameters for combined heave-and-pitch oscillations and, in general case, subject to action of orbital motion of fluid particles. To estimate added resistance the Beuklman-Gerritsma theory is used. Demonstrated in the course of calculations is the influence of aspect ratio and area of energy-saving wing upon the added resistance as well as upon its decrease when combining use of both bow and stern wings as compared to the case of using just one (bow or stern) wing. Obtained calculated data allow to understand the mechanism of the influence of energy-saving wings upon decrease of the amplitude of ship motions and the added resistance in waves.

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