System-Based Modelling of KCS Manoeuvring in Calm Water, Current and Waves

2020 ◽  
Author(s):  
Yuting Jin ◽  
Lucas J. Yiew ◽  
Allan R. Magee ◽  
Yingying Zheng
Keyword(s):  
Water Current ◽  
Flow Solver ◽  
Wave Drift ◽  
Future State ◽  
Steady Current ◽  
Mmg Model ◽  
Calm Water ◽  
Wave Effects ◽  
Object Of Study ◽  
Water Speed

Abstract Maritime autonomous surface ships (MASS) require accurate future state projection to initiate collision-avoidance manoeuvres. Forecasts of the vessels’ trajectories and motions are fundamentally based on the mathematical manoeuvring model, which is an essential component of their hydrodynamic digital twin nowadays. Using the benchmark container ship KCS as an object of study, this paper adopts a 4-DOF modular-type manoeuvring (MMG) model to predict the vessel trajectories in calm water and under the presence of steady current and regular waves. The current effects are treated as additional ship over water speed, while the wave effects are considered by superimposing the second-order mean wave drift loads to the calm water hull hydrodynamics. The wave drift loads are solved using the potential flow solver WASIM, which is based on Rankine panel method. The computed vessel trajectories and motions are compared with available literature results and show good correlation.

scholarly journals WAVE-CURRENT INTERACTION OVER SEABEDS WITH DIFFERENT ROUGHNESS: A STATISTICAL ANALYSIS

2017 ◽  
pp. 16
Author(s):  
Carla Faraci ◽  
Pietro Scandura ◽  
Enrico Foti
Keyword(s):  
Gaussian Distribution ◽  
Current Velocity ◽  
Mass Conservation ◽  
Distribution Functions ◽  
Wave Velocities ◽  
Velocity Statistics ◽  
Steady Current ◽  
Wave Effects ◽  
Current Interaction ◽  
Rippled Bed

Wave-current flow over seabeds covered with different roughness has been studied in order to deepen the knowledge on the statistical properties of the near-bed velocity. The results of three different experimental campaigns performed in the presence of a sandy bed, a gravel bed and a rippled bed, carried out superimposing a steady current onto an orthogonal wave, have been analysed. The statistics of the current velocity, including the wave effects on the steady current have been investigated. It has been observed that in the absence of waves, the fluctuations of the near-bed velocities closely follow a Gaussian distribution. When waves are also present, in order to obtain consistent near-bed velocity statistics, it is necessary to decouple the velocity events in the current direction by taking into account the sign of the wave velocities. In the latter case, the nature of the distribution functions is influenced by the mass conservation principle. A Gaussian distribution well describes the turbulent fluctuations obtained by removing the phase averaged velocity from the current velocity.

Wave Effects on the Turning Ability of an Ultra Large Container Ship in Shallow Water

2019 ◽  
Author(s):  
Manases Tello Ruiz ◽  
Marc Mansuy ◽  
Luca Donatini ◽  
Jose Villagomez ◽  
Guillaume Delefortrie ◽  
...  
Keyword(s):  
Shallow Water ◽  
Water Depth ◽  
Experimental Studies ◽  
Scale Model ◽  
Confined Water ◽  
The North ◽  
Calm Water ◽  
Wave Effects ◽  
Water Effects ◽  
Large Container

Abstract The influence of waves on ship behaviour can lead to hazardous scenarios which put at risk the ship, the crew and the surroundings. For this reason, investigating the effect of waves on manoeuvring is of relevant interest. Waves may impair the overall manoeuvring performance of ships hence increasing risks such as collisions, which are of critical importance when considering dense traffic around harbour entrances and in unsheltered access channels. These are conditions met by Ultra Large Container Ships (ULCS) when approaching a port, e.g. in the North Sea access channels to the main sea ports of Belgium. Note that due to the large draft of ULCS and the limited water depth, shallow water effects will also influenced the ship. Thus, in such scenarios the combined effects of shallow water and waves on the ship’s manoeuvring need to be studied. The present work investigates the effect of waves on the turning ability of an ULCS in shallow water. Simulations are carried out using the two time scale approach. The restricted water depth corresponds to 50% Under Keel Clearance (UKC). To gain a better insight on the forces acting on the ship, the propulsion, and the rudder behaviour in waves experimental studies were conducted. These tests were carried out in the Towing Tank for Manoeuvres in Confined Water at Flanders Hydraulics Research (in co-operation with Ghent University) with a scale model of an ULCS. Different wave lengths, wave amplitudes, ships speeds, propeller rates, and rudder angles were tested. The turning ability characteristics obtained from simulations in waves and calm water are presented, and discussed.

Numerical Evaluation of Ship Turning Performance in Regular and Irregular Waves

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Min-Guk Seo ◽  
Bo Woo Nam ◽  
Yeon-Gyu Kim
Keyword(s):  
Experimental Data ◽  
Degrees Of Freedom ◽  
Irregular Waves ◽  
Time Signal ◽  
Group Model ◽  
Frequency Wave ◽  
Wave Condition ◽  
Wave Drift ◽  
Mmg Model ◽  
Drift Force

Abstract In this study, ship's maneuvering performance in waves is evaluated using numerical computation. To this end, three degrees-of-freedom (3DOF) planar motions are considered, and modular-type maneuvering model (maneuvering modeling group model (MMG model)) is applied. As external force of the equation of motion, hull force, propulsion force, rudder force, and wave drift force are adopted. In order to calculate wave drift force, seakeeping program which is based on a higher-order Rankine panel method is used by considering wave frequency, wave heading, ship's forward speed, and ship's lateral speed. This wave drift force is pre-calculated, made into database, and used in time domain simulation. The developed simulation program is validated by comparing the computation results of a turning test in regular waves with experimental data. Using this program, turning performance in irregular waves is evaluated and sensitivities for time signal of wave elevation are investigated. Through this study, it is confirmed that the simplified method based on the MMG model including wave drift force can provide good agreement with experimental data in a practical point of view. It can be observed that the simulation results considering the lateral speed show better agreement with the experimental data than those without consideration. In the case of irregular wave condition, the turning performance can be affected by wave random phases. When the ship encounters the beam sea during the turning operation, the wave elevations at that time play an essential role in the change of ship speed and turning trajectory.

Hybrid Method for Predicting Ship Manoeuvrability in Regular Waves

2019 ◽  
Author(s):  
Tianlong Mei ◽  
Yi Liu ◽  
Manasés Tello Ruiz ◽  
Marc Vantorre ◽  
Evert Lataire ◽  
...  
Keyword(s):  
Experimental Data ◽  
Hybrid Method ◽  
Potential Flow ◽  
Flow Theory ◽  
Regular Waves ◽  
Potential Flow Theory ◽  
Hydrodynamic Derivatives ◽  
Mmg Model ◽  
Calm Water ◽  
Wave Induced

Abstract The ship’s manoeuvring behaviour in waves is significantly different from that in calm water. In this context, the present work uses a hybrid method combining potential flow theory and Computational Fluid Dynamics (CFD) techniques for the prediction of ship manoeuvrability in regular waves. The mean wave-induced drift forces are calculated by adopting a time domain 3D higher-order Rankine panel method, which includes the effect of the lateral speed and forward speed. The hull-related hydrodynamic derivatives are determined based on a RANS solver using the double body flow model. The two-time scale method is applied to integrate the improved seakeeping model in a 3-DOF modular type Manoeuvring Modelling Group (MMG model) to investigate the ship’s manoeuvrability in regular waves. Numerical simulations are carried out to predict the turning circle in regular waves for the S175 container carrier. The turning circle’s main characteristics as well as the wave-induced motions are evaluated. A good agreement is obtained by comparing the numerical results with experimental data obtained from existing literature. This demonstrates that combining potential flow theory with CFD techniques can be used efficiently for predicting the manoeuvring behaviour in waves. This is even more true when the manoeuvring derivatives cannot be obtained from model tests when there is lack of such experimental data.

scholarly journals A Framework of Numerically Evaluating a Maneuvering Vessel in Waves

2020 ◽  
Vol 8 (6) ◽  
pp. 392 ◽  
Author(s):  
Zhitian Xie ◽  
Jeffrey Falzarano ◽  
Hao Wang
Keyword(s):  
Wave Loads ◽  
Environmental Loads ◽  
Adverse Conditions ◽  
Damping Effect ◽  
Hydrodynamic Phenomenon ◽  
Calm Water ◽  
Wave Effects ◽  
Maneuvering In Waves ◽  
Wave Drift Damping ◽  
Propulsion Power

Maneuvering in waves is a hydrodynamic phenomenon that involves both seakeeping and maneuvering problems. The environmental loads, such as waves, wind, and current, have a significant impact on a maneuvering vessel, which makes it more complex than maneuvering in calm water. Wave effects are perhaps the most important factor amongst these environmental loads. In this research, a framework has been developed that simultaneously incorporates the maneuvering and seakeeping aspects that includes the hydrodynamics effects corresponding to both. To numerically evaluate the second-order wave loads in the seakeeping problem, a derivation has been presented with a discussion and the Neumann-Kelvin linearization has been applied to consider the wave drift damping effect. The maneuvering evaluations of the KVLCC (KRISO Very Large Crude Carrier) and KCS (KRISO Container Ship) models in calm water and waves have been conducted and compared with the model tests. Through the comparison with the experimental results, this framework had been proven to provide a convincing numerical prediction of the horizontal motions for a maneuvering vessel in waves. The current framework can be extended and contribute to the IMO (International Maritime Organization) standards for determining the minimum propulsion power to maintain the maneuverability of vessels in adverse conditions.

Influence of Water Speed on Tadpoles of Ranidella signifera and R. riparia (Anura:Leptodactylidae)

1980 ◽  
Vol 28 (1) ◽  
pp. 79 ◽  
Author(s):  
FJ Odendaal ◽  
CM Bull
Keyword(s):  
Water Flow ◽  
South Australia ◽  
Breeding Habitat ◽  
Water Current ◽  
Similar Species ◽  
Flinders Ranges ◽  
Species Overlap ◽  
Influence Of Water ◽  
The Difference ◽  
Water Speed

Ranidella riparia is restricted to the Flinders Ranges of South Australia. and has a distribution largely allopatric to that of the morphologically similar species, R. signifera. The distributions of these two species overlap in the lower Flinders Ranges. In an experimental water flow, tadpoles of R. riparia were less often moved by the water current than those of R. signifera, and the difference increased with increasing water speed. In the Flinders Ranges most of the breeding habitat for frogs is in fast flowing creeks. The likelihood that tadpoles of R. signifera would be swept away in these creeks may be a factor restricting its distribution in this area.

Flow Induced Motions on Multi Column Floaters

2007 ◽  
Author(s):  
Olaf J. Waals ◽  
Amal C. Phadke ◽  
Stephen Bultema
Keyword(s):  
Frequency Response ◽  
Global Analysis ◽  
Low Frequency ◽  
Mass Ratio ◽  
Complex Flow ◽  
Lower Mass ◽  
Steady Current ◽  
Calm Water ◽  
Mean Current ◽  
Motion Behavior

Recent years have shown an increasing interest in low frequency response of offshore floaters in current. Spar VIM behavior and Semi Submersible flow induced behavior is known from calm water tow tests. Recent tow test projects have also shown low frequency TLP response in steady current. The motions from the model tests are used in the global analysis of the mooring systems and risers for these platforms. This paper discusses the dynamic behavior in current of multi column floaters and the associated complex flow patterns. Shielding between columns is addressed as well as the effect of mass ratio (i.e. floater mass divided by displacement). It is shown that lower mass ratios such as for conventional TLP’s may result in larger sway response than for deep draft semi submersibles. The motion behavior is discussed as well as the increase in total mean current loads due to transverse motions.

The effect of locomotor activity on the growth of brook charr, Salvelinus fontinalis Mitchill

1987 ◽  
Vol 65 (4) ◽  
pp. 843-846 ◽  
Author(s):  
Pierre East ◽  
Pierre Magnan
Keyword(s):  
Salvelinus Fontinalis ◽  
Dry Weight ◽  
Individual Growth ◽  
Water Current ◽  
Brook Charr ◽  
Internal Organs ◽  
Relative Water ◽  
Wet Weight ◽  
The Individual ◽  
Water Speed

Yearling hatchery-reared brook charr, Salvelinus fontinalis Mitchill, were trained during a 20-day period at different water velocities: 0.00, 0.85, 1.72, and 2.50 body lengths/s (bl/s). Our results indicate that growth (wet weight), food conversion efficiency, and the deposition of lipids on the digestive tract were maximized at 0.85 bl/s. The individual growth (wet weight) was also more homogeneous at this water speed. The storage of lipids in the white muscles was significantly lower in still water (0.00 bl/s) while the increase in length, the increase in the dry weight of the carcass (whole fish less internal organs), and the relative water content of the muscle showed no significant differences between the tested water velocities. Behavioural observations indicated that the frequency of agonistic behaviours between individuals was important in still water, but decreased significantly in the presence of a water current.

Design of the University of New Orleans Ship-Offshore University Laboratory for Offshore Industry Support

1988 ◽  
Vol 110 (3) ◽  
pp. 133-140 ◽  
Author(s):  
R. Latorre
Keyword(s):  
New Orleans ◽  
Water Current ◽  
Offshore Structure ◽  
Water Research ◽  
Towing Tank ◽  
Calm Water ◽  
Tank Design ◽  
Offshore Industry ◽  
The University ◽  
University Laboratory

On July 23, 1987, the University of New Orleans (UNO) dedicated its new Engineering Building, which houses a 38.3 m×4.57 m×0–2.134 m deep ship-offshore university laboratory tow tank. This paper covers the initial stages of the project and summarizes the towing tank design for ship-offshore testing. The tank is configured for three purposes: 1) conventional ship research in deep water with calm water or waves; 2) offshore structure testing with provision for observation and anchoring; 3) shallow water research in calm water, current, and waves.

A Joint-Industry Effort to Develop and Verify CFD Modeling Practice for Predicting Hydrodynamic Coefficients on Bare Riser Surfaces

2021 ◽  
Author(s):  
Hyunchul Jang ◽  
Madhusuden Agrawal ◽  
Dongwhan Lee ◽  
Wei Xu ◽  
Jerry Huang ◽  
...  
Keyword(s):  
Forced Oscillation ◽  
Lift Coefficient ◽  
Circular Cross Section ◽  
Cfd Modeling ◽  
First Year ◽  
Cfd Analysis ◽  
Hydrodynamic Coefficients ◽  
Steady Current ◽  
Calm Water ◽  
Modeling Practice

Abstract Hydrodynamic force coefficients are important parameters in design and assessment of marine risers. The hydrodynamic coefficients are widely used for assessing marine riser responses due to floater motion excitation and vortex-induced vibrations (VIV). Traditionally, the hydrodynamic coefficients have been obtained from physical model tests on short rigid riser sections. Recently, the offshore industry has started to use computational fluid dynamics (CFD) analysis for predicting the hydrodynamic coefficients due to the recent advancement of CFD software and high-performance computing capabilities, but a reliable CFD modeling practice is requested for CFD analysis to be a more widely accepted prediction tool in the industry. A joint industry effort has been made for developing and verifying the reliable CFD modeling practice through a working group of the Reproducible Offshore CFD JIP. In the working group, a CFD modeling practice document was written based on existing practices already validated for model test data, and verified by blind validations with three CFD practitioners. The first year works are focused on the bare riser with circular cross-section, and the second year work will be extended to the other riser sections such as staggered buoyancy module and straked riser. This paper presents the working group’s first-year verification activities for a bare riser with circular cross-section. The verification works covers three test problems: 1) stationary simulation in steady current, 2) forced-oscillation in calm water, 3) forced-oscillation in steady current. In the stationary simulation, mean drag coefficient, standard deviation of lift coefficient, and Strouhal numbers are compared. In the forced-oscillation simulation in calm water, the fully-submerged riser section oscillates with a sinusoidal motion, and damping and added mass coefficients are compared. In the forced-oscillation simulation in current, the riser section oscillates in cross-flow direction to the steady current, and lift coefficient and added mass coefficient are compared. By following the modeling practice, the CFD predictions are consistent with each other and close to the model test data for a majority of test cases.

Sign in / Sign up

Export Citation Format

Share Document