Numerical and Experimental Analysis of Added Resistance of Ships in Waves

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Ould el Moctar ◽  
Sebastian Sigmund ◽  
Jens Ley ◽  
Thomas E. Schellin
Keyword(s):  
Water Resistance ◽  
Frictional Resistance ◽  
Medium Size ◽  
Total Resistance ◽  
Added Resistance ◽  
Short Waves ◽  
Radiation Forces ◽  
Calm Water ◽  
Added Resistance In Waves ◽  
Force Components

Two Reynolds-Averaged Navier–Stokes (RANS) based field methods numerically predicted added resistance in regular head waves for a 14,000 TEU containership and a medium size cruise ship. Long and short waves of different frequencies were considered. Added resistance was decomposed into diffraction and radiation force components, whereby diffraction forces were obtained by restraining the ship in waves and radiation forces by prescribing the motions of the ship in calm water. In short waves, the diffraction part of total resistance was dominant as almost no ship motions were induced. In long waves, the sum of diffraction and radiation forces exceeded total resistance, i.e., the interaction of these two force components, which caused the reduction of total resistance, needed to be accounted for. Predictions were compared with model test measurements. Particular emphasis was placed on the following aspects: discretization errors, frictional resistance as part of total added resistance in waves, and diffraction and radiation components of added resistance in waves. Investigations comprised two steps, namely, a preliminary simulation to determine calm water resistance and a second simulation to compute total resistance in waves, always using the same grids. Added resistance was obtained by subtracting calm water resistance from total averaged wave resistance. When frictional resistance dominated over calm water resistance, which holds for nearly all conventional ships at moderate Froude numbers, high grid densities were required in the neighborhood surrounding the hull as well as prism cells on top of the model's surface.

Numerical and Experimental Analysis of Added Resistance of Ships in Waves

2015 ◽  
Author(s):  
Ould el Moctar ◽  
Sebastian Sigmund ◽  
Thomas E. Schellin
Keyword(s):  
Water Resistance ◽  
Frictional Resistance ◽  
Medium Size ◽  
Total Resistance ◽  
Added Resistance ◽  
Short Waves ◽  
Radiation Forces ◽  
Calm Water ◽  
Added Resistance In Waves ◽  
Force Components

A RANS-based field method numerically predicted added resistance in regular head waves for a 14000 TEU containership (Duisburg Test Case) and a medium-size cruise ship. We concentrated our investigations on short waves. For different frequencies, we decomposed added resistance into diffraction and radiation force components, whereby diffraction forces were obtained by restraining the ship in waves and radiation forces, by prescribing the motions of the ship in calm water. In short waves, the diffraction part of total resistance was dominant as almost no ship motions were induced. In long waves, the sum of diffraction and radiation forces exceeded total resistance, i.e., the interaction of these two force components, which caused the reduction of total resistance, had to be accounted for. Predictions were compared with model test measurements. Particular emphasis was placed on the following aspects: discretization errors, frictional resistance as part of total added resistance in waves, diffraction and radiation components of added resistance in waves, and the influence of surge motion on added resistance. Investigations comprised two steps, namely, a preliminary simulation to determine calm-water resistance and a second simulation to compute total resistance in waves, always using the same grids. Added resistance was obtained by subtracting calm-water resistance from total averaged wave resistance. When frictional resistance dominated calm-water resistance, which holds for nearly all conventional ships at moderate Froude numbers, high grid densities were required in the neighborhood surrounding the hull.

scholarly journals Study on Hull Optimization Process Considering Operational Efficiency in Waves

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 898
Author(s):  
Beom-Soo Kim ◽  
Min-Jae Oh ◽  
Jae-Hoon Lee ◽  
Yong-hwan Kim ◽  
Myung-Il Roh
Keyword(s):  
Water Resistance ◽  
Operational Efficiency ◽  
Free Form ◽  
Total Resistance ◽  
Added Resistance ◽  
Deformation Method ◽  
Cross Sectional ◽  
Hull Form ◽  
Strip Theory ◽  
Calm Water

This study investigates the optimization of the hull form of a tanker, considering the operational efficiency in waves, in accordance with the recent Energy Efficiency Design Index regulation. For this purpose, the total resistance and speed loss of the ship under representative sea conditions were minimized simultaneously. The total resistance was divided into three components: calm water resistance, added resistance due to wind, and to waves. The first two components were calculated using regression formulas, and the last component was estimated using the strip theory, far-field method, and the short-wave correction formula. Next, prismatic coefficient, waterline length, waterplane area, and flare angle were selected as design variables from the perspective of operational efficiency. The hull form was described as a combination of cross-sectional curves. A combination of the method shifting these sections in the longitudinal direction and the Free-Form Deformation method was used to deform the hull. As a result of applying the non-dominated sorting genetic algorithm to a tanker, the hull was deformed thinner and longer, and it was determined that the total resistance and speed loss were reduced by 3.58 and 10.2%, respectively. In particular, the added resistance due to waves decreased significantly compared to the calm water resistance, which implies that the present tendency differs from conventional ship design that optimizes only the calm water resistance.

The Effect of Bow Steepness and Flare on the Resistance of Sailing Yachts in Calm Water and Waves

2001 ◽  
Author(s):  
J. A. Keuning ◽  
R. Onnink ◽  
A. Damman
Keyword(s):  
Water Resistance ◽  
Added Resistance ◽  
University Of Technology ◽  
Head Waves ◽  
Master Thesis ◽  
Calm Water ◽  
Added Resistance In Waves ◽  
Bow Flare ◽  
Sailing Yacht ◽  
Resistance Performance

In this paper some results are presented of two studies carried out at the Ship hydromechanics Department of the Delft University of Technology: one, on the influence of an increase of stem steepness of a sailing yacht, and another, which was largely carried out by T.J.E. Tincelin as part of his master thesis at Delft University of Technology, on the effect of above waterline bow flare are presented. To investigate the influence of bow steepness a model of the Delft Systematic Yacht Hull Series (DSYHS) has been used as a parent model of a new small subseries with two additional derivatives each with increased bow steepness. The influence on both the calm water resistance and the added resistance in head waves has been investigated. To investigate the influence of bow flare, two models of a typical "Open 60" design have been used: one "normal" and one with almost no flare in the bowsections. These have been tested in calm water and in both head- and following­waves to investigate the effects of this difference in bow shape on the calm water resistance, on added resistance in waves, and on the relative motions at the bow. The results are presented and some comparisons with calculations made. Also some general conclusions with respect to resistance, performance and safety are drawn.

Detailed Study on the Behavior of Ships in Very Short Waves

2020 ◽  
Author(s):  
Saori Yokota ◽  
Mariko Kuroda ◽  
Ryohei Fukasawa ◽  
Hiroki Ohba ◽  
Masaru Tsujimoto
Keyword(s):  
Sensitivity Analysis ◽  
Fuel Consumption ◽  
Added Resistance ◽  
Regular Waves ◽  
Short Waves ◽  
Added Resistance In Waves ◽  
Tank Test ◽  
Ship Performance ◽  
Ship Operation ◽  
Actual Seas

Abstract Considering the sea conditions in which a large ship encountered in operation, the ship’s behavior in very short waves is important. However, the evaluation of the ship performance in very short waves was not enough validated by tank tests. Because it is difficult to generate waves with enough accuracy due to the performance of the wave generator. In this paper, it is shown that tank tests of added resistance in the regular waves including the very short waves are conducted in the Actual Sea Model Basin at National Maritime Research Institute, MPAT for DTC container ship and accurate results are obtained. The test results are compared with the benchmarks published by SHOPERA (Energy Efficient Safe SHip OPERAtion). In addition, three curves of the added resistance in the regular waves based on the results of the tank test are compared and the sensitivity analysis of energy efficiency is discussed. In the sensitivity analysis, the performance simulator for ships in actual seas (VESTA) is used, and a comparison is carried out for the fuel consumption calculated from the frequency response of each added resistance in waves. As a result, it is found that the tendency in added resistance in very short waves affects the fuel consumption and the decrease of ship speed.

Sailing Yacht Performance in Calm Water and in Waves

1993 ◽  
Author(s):  
J. Gerritsma ◽  
J. A. Keuning ◽  
A. Versluis
Keyword(s):  
Model Experiment ◽  
Irregular Waves ◽  
Current Interest ◽  
Added Resistance ◽  
Hull Form ◽  
Wide Range ◽  
Calm Water ◽  
Added Resistance In Waves ◽  
Sailing Yacht ◽  
Calculated Analysis

The Delft systematic Yatch Hull Series has been extended to a total of 39 hull form variations, covering a wide range of length displacement ratios and other form of parameters. The total set of model experiment results, upright and heeled resistance as well as sideforce and stability, had been analysed and polynomial expressions to approximate these quantities are presented. In view of the current interest in the performance of sailing yachts in waves, the added resistance in irregular waves of 8 widely different hull variations has been calculated. Analysis of the results shows that the added resistance in waves strongly depends on the product of displacement-length ratio and the gyradius of the pitching motion.

Scaling of Resistance From Surface-Effect Ship Model Tests

2013 ◽  
Vol 29 (02) ◽  
pp. 66-75
Author(s):  
Chris B. McKesson ◽  
Lawrence J. Doctors
Keyword(s):  
Surface Effect ◽  
Frictional Resistance ◽  
Wave Resistance ◽  
Complex Case ◽  
Total Resistance ◽  
Towing Tank ◽  
Classic Article ◽  
Calm Water ◽  
Surface Effect Ship ◽  
Friction Line

In the case of conventional (displacement) hulls, model testing is based on the assumption (with or without certain refinements) that the total resistance can be expressed as:RT=RF+RR(1)where Rt is measured in the towing tank, and the frictional resistance, Rf, can be accurately estimated by the application of a friction line and the use of the calm-water wetted surface. It is assumed that the dimensionless residuary resistance RR is the same for the model and the prototype vessel. Our article may be considered to be an extension of the classic article by Wilson, Wells, and Heber (1978) to the more complex case of the surface-effect ship, as follows. Specifically, we opine that:RT=RF+RW+RH+RS+RM+RSPRAY(2)Here, Rw is the wave resistance of the vessel (caused by a combination of the actions of the cushion pressure and the two sidehulls), RH is the transom (hydrostatic) drag, Rs is the seal drag, Rm is the momentum drag, and RspRay is the spray drag. Rt is the only one of these quantities that is measured during the model test. The other components require the use of a variety of estimates. In the article, we present specific examples of our approach as applied to a number of tests on surface-effect ship models that we have studied in recent years.

scholarly journals Hull form optimization in the conceptual design stage considering operational efficiency in waves

2018 ◽  
Vol 233 (3) ◽  
pp. 745-759 ◽  
Author(s):  
Yoo-Won Jung ◽  
Yonghwan Kim
Keyword(s):  
Optimization Method ◽  
Operational Efficiency ◽  
Hydrodynamic Performance ◽  
Design Stage ◽  
Total Resistance ◽  
Added Resistance ◽  
Slender Body Theory ◽  
Hull Form ◽  
Weather Factor ◽  
Calm Water

This study focuses on the optimization of ship dimensions by considering hydrodynamic performance in waves. In actual seaways, a ship experiences speed loss due to environmental loads by waves and wind. Therefore, along with calm water resistance, speed loss in waves should be considered in the hull form design in order to improve operational efficiency in waves. However, a trade-off may be needed between total resistance on the ship and the speed loss in waves. To address this problem, Non-dominated Sorting Genetic Algorithm II, which is a multi-objective optimization method, is used to minimize the total resistance on a ship in seaways and the speed loss by additional resistance. In the optimization process, added resistance is predicted using a numerical method based on slender-body theory, Maruo’s far-field formulation, and an empirical formula for added resistance in short waves. The speed loss in waves, which can be expressed by a weather factor ( fw), is estimated using power–speed curves. This article introduces some examples of the sensitivity analysis of added resistance and speed loss in waves to the variations of ship dimensions. Finally, the optimization solutions on a Pareto front set are compared to a basis ship in terms of hull form, and the corresponding hydrodynamic performances are evaluated.

Study of Wave Added Resistance on Wigley Ship

2013 ◽  
Vol 468 ◽  
pp. 105-109
Author(s):  
Tao Sun ◽  
Ming Hui Yuan ◽  
Wei Wang ◽  
Nan Ye
Keyword(s):  
Total Resistance ◽  
Added Resistance ◽  
Ship Model ◽  
Seakeeping Performance ◽  
Head Waves ◽  
Free Model ◽  
Calm Water ◽  
Significant Research ◽  
Energy Consuming ◽  
Hydrodynamic Potential

Global warming is becoming a serious problem nowadays. The emissions of greenhouse gas from vessels draw great attentions. As a significant research part of vessel seakeeping performance, resistance capability exert pretty effect on energy consuming. A Wigley ship model is set as the object to compute constraint and free model in calm water and head waves on resistance and hydrodynamic potential coefficients by STAR-CCM. Differences are discussed between both models. Effects on calculation of hydrostatic resistance ignoring trim and heave are revealed .Wave added resistance of free model is computed and compared at different amplitudes and wavelengths. How trim and heave matter the computed results are discussed. So does how wavelength and amplitudes influence total resistance is considered.

scholarly journals ANALISA KOMPONEN HAMBATAN KAPAL IKAN TRADISIONAL DI PERAIRAN CILACAP

2016 ◽  
Vol 9 (1) ◽  
pp. 1
Author(s):  
S Samuel
Keyword(s):  
Water Resistance ◽  
Frictional Resistance ◽  
Slender Body ◽  
Resistance Components ◽  
Fishing Boat ◽  
Calm Water ◽  
Double Hull ◽  
Traditional Fishing ◽  
Body Method ◽  
Resistance Component

<p><em>RESISTANCE COMPONENT ANALYSIS OF TRADITIONAL FISHING BOAT IN CILACAP</em></p><p><em><br /></em></p><p><em>Monohull fishing boats used to catch fish is modified into a catamaran boat. The purpose of this modification is to get more fish. Catamaran ship has a double hull, but with the double hull ships resulted in increasingly complex resistances. It is interesting to study in depth about the resistance components of Catamaran boat. Resistance Components not only consist of surge resistance, frictional resistance, and the form resistance but with the distance between demihull causing interference waves. There are many research results of Catamaran boat in that aspect, but the data and information obtained from the experiment is still inadequate. In addition, there is still lack of accuracy particularly in predicting interference resistance component in calm water (calm-water resistance) as a result of the distance between the demihull. This study aims to describe the resistance component at Catamaran boat by using slender body method.</em><strong><em></em></strong></p><p align="center"><strong> </strong></p><p><strong>Keywords</strong>: <em>catamaran, Cilacap, slender body method</em></p><p> </p><p align="center"><strong>ABSTRAK</strong></p><p align="center"><strong> </strong></p><p><em>Kapal ikan monohull yang biasa digunakan untuk mencari ikan dimodifikasi menjadi kapal catamaran. Tujuan modifikasi ini untuk mendapatkan muatan ikan yang lebih banyak. Kapal Catamaran mempunyai dua lambung, tetapi dengan adanya dua lambung mengakibatkan hambatan kapal semakin kompleks. Menarik untuk dikaji lebih lanjut tentang komponen hambatan kapal Catamaran. Komponen hambatan tidak hanya terdiri dari hambatan gelombang, hambatan gesek, dan hambatan bentuk namun dengan adanya jarak antar demihull sehingga menimbulkan interferensi gelombang. Sudah banyak dijumpai hasil riset kapal Catamaran pada aspek tersebut, tetapi data dan informasi yang diperoleh dari eksperimen masih kurang memadai. Disamping itu, masih ditemukan ketidak-akurasian khususnya dalam memprediksi interferensi komponen hambatan pada air tenang (calm-water resistance) akibat dari adanya jarak antar demihull tersebut. Penelitian ini bertujuan untuk memaparkan komponen hambatan pada kapal Catamaran dengan menggunakan slender body method. </em></p><p> </p><p><strong>Kata kunci</strong>: <em>catamaran, Cilacap, slender body method</em></p>

scholarly journals Evaluation of the Effect of Container Ship Characteristics on Added Resistance in Waves

2020 ◽  
Vol 8 (9) ◽  
pp. 696
Author(s):  
Ivana Martić ◽  
Nastia Degiuli ◽  
Andrea Farkas ◽  
Ivan Gospić
Keyword(s):  
Point Of View ◽  
Irregular Waves ◽  
Design Stage ◽  
Radius Of Gyration ◽  
Container Ship ◽  
Added Resistance ◽  
Head Waves ◽  
Calm Water ◽  
Added Resistance In Waves ◽  
Longitudinal Position

Added resistance in waves is one of the main causes of an increase in required power when a ship operates in actual service conditions. The assessment of added resistance in waves is important from both an economic and environmental point of view, owing to increasingly stringent rules set by the International Maritime Organization (IMO) with the aim to reduce CO2 emission by ships. For that reason, it is desirable to evaluate the added resistance in waves already in the preliminary ship design stage both in regular and irregular waves. Ships are traditionally designed and optimized with respect to calm water conditions. Within this research, the effect of prismatic coefficient, longitudinal position of the centre of buoyancy, trim, pitch radius of gyration, and ship speed on added resistance is investigated for the KCS (Kriso Container Ship) container ship in regular head waves and for different sea states. The calculations are performed using the 3D panel method based on Kelvin type Green function. The results for short waves are corrected to adequately take into account the diffraction component. The obtained results provide an insight into the effect of variation of ship characteristics on added resistance in waves.

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