Maneuvering characteristics in calm water and regular waves for ONR Tumblehome

2014 ◽  
Author(s):  
Haitham Abdalla Elshiekh
Keyword(s):  
Regular Waves ◽  
Calm Water ◽  
Onr Tumblehome

A Nonlinear Mathematical Model for Ship Turning Circle Simulation in Waves

2005 ◽  
Vol 49 (02) ◽  
pp. 69-79 ◽  
Author(s):  
Ming-Chung Fang ◽  
Jhih-Hong Luo ◽  
Ming-Ling Lee
Keyword(s):  
Mathematical Model ◽  
Degrees Of Freedom ◽  
Regular Waves ◽  
Nonlinear Mathematical Model ◽  
Ship Maneuvering ◽  
Sea Trial ◽  
Six Degrees Of Freedom ◽  
Strip Theory ◽  
Calm Water ◽  
Maneuvering Motion

In the paper, a simplified six degrees of freedom mathematical model encompassing calm water maneuvering and traditional seakeeping theories is developed to simulate the ship turning circle test in regular waves. A coordinate system called the horizontal body axes system is used to present equations of maneuvering motion in waves. All corresponding hydrodynamic forces and coefficients for seakeeping are time varying and calculated by strip theory. For simplification, the added mass and damping coefficients are calculated using the constant draft but vary with encounter frequency. The nonlinear mathematical model developed here is successful in simulating the turning circle of a containership in sea trial conditions and can be extended to make the further simulation for the ship maneuvering under control in waves. Manuscript received at SNAME headquarters February 19, 2003; revised manuscript received January 27, 2004.

Numerical simulations of a ship obliquely advancing in calm water and in regular waves

2020 ◽  
Vol 103 ◽  
pp. 102330
Author(s):  
Wei Zhang ◽  
Ould el Moctar ◽  
Thomas E. Schellin
Keyword(s):  
Numerical Simulations ◽  
Regular Waves ◽  
Calm Water

Numerical Study on the Maneuvering of a Ship in Waves Based on Unified State Space Model

2016 ◽  
Author(s):  
Rameesha Thayale Veedu ◽  
Parameswaran Krishnankutty
Keyword(s):  
State Space ◽  
Numerical Study ◽  
State Space Model ◽  
Container Ship ◽  
Regular Waves ◽  
Ship Maneuvering ◽  
Space Model ◽  
Water Conditions ◽  
Calm Water ◽  
Early Design Stages

Ship maneuvering performance is usually predicted in calm water conditions, which provide valuable information about ship’s turning ability and its directional stability in the early design stages. Investigation of maneuvering simulation in waves is more realistic since the ship usually sails through waves. So it is important to study the effect of waves on the turning ability of a ship. This paper presents the maneuvering simulation for a container ship in presence of regular waves based on unified state space model for ship maneuvering. Standard maneuvers like turning circle and zigzag maneuver are simulated for the head sea condition and the same are compared with calm water maneuvers. The present study shows that wave significantly affects the maneuvering characteristics of the ship and hence cannot be neglected.

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.

Experimental appraisal of hydrodynamic performance and motion of a single-stepped high-speed vessel in calm water and regular waves

2020 ◽  
pp. 095440622096812
Author(s):  
Sayyed Mahdi Sajedi ◽  
Parviz Ghadimi ◽  
Aliakbar Ghadimi ◽  
Mohammad Sheikholeslami
Keyword(s):  
High Speed ◽  
Single Step ◽  
Hydrodynamic Performance ◽  
Sea Waves ◽  
Regular Waves ◽  
Height Range ◽  
Step Model ◽  
Speed Range ◽  
Calm Water ◽  
Laboratory Models

High-speed vessels exhibit various motions and accelerations in calm water and sea waves. For examining the behavior of high-speed vessels, it is possible to examine these movements in laboratory models. In this paper, a single-step model in calm water is experimentally tested and compared with a model of no step. The speed range of these vessels is 1 m/s to 9 m/s equivalent to Beam Froude numbers of 0.43 to 3.87. During these experiments, the resistance parameters, trim, bow, and stern rise-up as well as the center of the gravity are measured. The non-step model has longitudinal instability at a speed of 8 m/s. This instability is avoided when the vessel is equipped by a transversal step. The vessel's trim and resistance are also reduced in the planing mode in calm water. Subsequently, hydrodynamic performance and its seakeeping condition in the planing regime are investigated for both vessels in regular waves. The single-step and non-step vessels are tested in the wavelength range of [Formula: see text], and the wave height range of 6 to 18 centimeters. It is observed that stepped vessel experiences lower motions and bow accelerations and less added resistance in comparison to the non-stepped vessel.

Numerical Simulation of Submarine Surfacing With Six Degrees of Freedom in Regular Waves

2016 ◽  
Author(s):  
Weijian Jiang ◽  
Zhilin Wang ◽  
Ran He ◽  
Xianzhou Wang ◽  
Dakui Feng
Keyword(s):  
Numerical Simulation ◽  
Wave Height ◽  
Velocity Fluctuation ◽  
Degrees Of Freedom ◽  
Wave Length ◽  
Roll Angle ◽  
Regular Waves ◽  
Rolling Moment ◽  
Six Degrees Of Freedom ◽  
Calm Water

Submarine surfacing in waves is three dimensional unsteady motion and includes complex coupling between force and motion. This paper uses computational fluid dynamics (CFD) to solve RANS equation with coupled six degrees of freedom solid body motion equations. RANS equations are solved by finite difference method and PISO arithmetic. Level-set method is used to simulate the free surface. Computations were performed for the standard DARPA SUBOFF model. The structured dynamic overset grid is applied to the numerical simulation of submarine surfacing (no forward speed) in regular waves and computation cases include surfacing in the calm water, transverse regular waves with different ratio of wave height and submarine length (h/L = 0.01, 0.02, 0.03, 0.04) and transverse regular waves with different ratio of wave length and submarine length (λ/L = 0.5, 1, 1.5). The asymmetric vortices in the process of submarine surfacing can be captured. It proves that roll instability is caused by the destabilizing hydrodynamic rolling moment overcoming the static righting moment both under the water and in regular waves. Relations among maximum roll angle, surfacing velocity fluctuation and wave parameters are concluded by comparison with variation trend of submarine motion attitude and velocity of surfacing in different wave conditions. Simulation results confirm that wave height h/L = 0.04 and wave length λ/L = 1.5 lead to surfacing velocity fluctuation significantly. Maximum roll angle increases with the increase of wave height and wave length. Especially the law presents approximate linear relationship. Maximum roll angle with wave height (h/L = 0.04) can reach to 7.29° while maximum roll angle with wave length (λ/L = 1.5) can reach to 5.79° by contrast with 0.85° in calm water. According to the above conclusions, maneuverability can be guided in the process of submarine surfacing in waves in order to avoid potential safety hazard.

The Transient Capsize Diagram—A New Method of Quantifying Stability in Waves

1991 ◽  
Vol 35 (01) ◽  
pp. 58-62 ◽  
Author(s):  
R. C. T. Rainey ◽  
J. M. T. Thompson
Keyword(s):  
Computer Simulation ◽  
Dynamic Systems ◽  
Wave Steepness ◽  
Dynamic Systems Theory ◽  
Regular Waves ◽  
Desktop Computers ◽  
Strip Theory ◽  
Calm Water ◽  
Recent Developments ◽  
The Stability

It is argued that a plot of wave steepness against wave period, showing the combinations which cause capsize, is a well-defined measure of the stability of a ship or ocean vehicle in waves, provided the conditions are transient, that is, the vessel is initially in relatively calm water, and is suddenly hit by a train of regular waves. This conclusion is a consequence of recent developments in dynamic systems theory. Such Transient Capsize Diagrams can obviously be obtained by model testing; it is also argued that they could be obtained by computer simulation on contemporary desktop computers, taking advantage of recent developments in nonlinear strip theory.

Experiments and CFD for ONRT Course Keeping and Turning Circle Maneuvering in Regular Waves

2015 ◽  
Author(s):  
Hamid Sadat-Hosseini ◽  
Yugo Sanada ◽  
Frederick Stern
Keyword(s):  
Experimental Data ◽  
Validation Study ◽  
High Frequency ◽  
Low Frequency ◽  
Harmonic Amplitude ◽  
Regular Waves ◽  
Effective Power ◽  
Head Waves ◽  
Calm Water ◽  
Turning Maneuver

CFD computations are validated for course keeping and maneuvering of ONRT ship hull advancing at Froude number 0.2 in regular waves. The course keeping computations are conducted for various wave headings (0, 45, 90, 135, 180 deg) with λ/L=1.0 and H/λ=0.02. The maneuvering computation is performed for a turning maneuver with 35 deg rudder deflection for the ship located initially in head waves with λ/L=1.0 and H/λ=0.02. The 6DOF motions/velocities and wave elevation are validated against available experimental data. For course keeping, the validation study focuses on the 0th, 1st and 2nd harmonic amplitude of motions/velocities. The effective and propeller power are also investigated using CFD results. For the turning maneuver, the validation study focuses on the characteristics of turning trajectory in waves and low and high frequency of motions/velocities. For course keeping, the 0th and 2nd harmonic of motions show an average error of 30%DR whereas 1st harmonic amplitude predictions show a smaller error with an average value of 12%DR over all the wave headings. For all harmonics, the largest error value was for the stern quartering wave and the smallest value was often for the head wave conditions. The study on the propeller performance in course keeping showed that the effective power required for the ship was largest in head waves, about 30% more than the power required in calm water. The effective power decreased by increasing the wave heading such that the values were close to the effective power in calm water for wave heading > 90 deg. The propeller efficiency was found to be higher in waves. The increase of the propeller efficiency was largest for wave heading of 45 deg, about 10% increase compared to calm water. For the turning maneuver, the trajectory was well predicted with E=2.9%D and 3.7%D for the advance distance and tactical diameter, respectively. The drift distance was under predicted by 9%D and the drift angle is predicted 87 deg whereas the experimental data shows 55 deg. The comparison of course keeping and turning showed the low frequency values are significantly affected by turning. The low frequency values of the experimental heave and pitch showed the wave is distorted by the ship motion for the second and third turning cycles. The high frequency values of turning and course keeping are similar for the heave and pitch motions and different for other motions/velocities. CFD shows good agreement for the high frequency values of heave, pitch and roll motions and low frequency values of most motions/velocities excluding heave and pitch.

The Influence of Towing Method on Planing Boat Accelerations in Waves

2017 ◽  
Author(s):  
Carolyn Judge ◽  
Bill Beaver ◽  
John Zseleczk
Keyword(s):  
Rigid Body ◽  
Digital Measurement ◽  
Vertical Acceleration ◽  
Regular Waves ◽  
Towing Tank ◽  
Analog Signals ◽  
Hull Structure ◽  
Calm Water ◽  
Low Pass ◽  
Body Response

TRACT Vertical acceleration measurements are often used to evaluate the “rigid body” response of a planing hull to hydrodynamic forces in waves. Unfortunately accelerometers respond to both the rigid body hull motions of interest and to unwanted vibrations, which if not addressed, produce artificially higher peak acceleration values (Riley, et.al, 2010). In full scale hulls, vibrations from the propulsors are telegraphed through the hull structure to the accelerometer. In towing tank models vibrations from the carriage are transmitted by the tow post through the hull and to the accelerometer. Historically, different methods have been used to eliminate the unwanted acceleration components including engineering judgement, electronic low-pass filtering of analog signals and postprocessing of digital measurement records using computational filtering techniques. This paper documents a study of the effects of different towing methods on planing boat model accelerations. A four foot long planing hull was tested in calm water and in waves using three different towing methods: - Traditional heave post with model towed at constant velocity - Self-propelled model mounted on a lightweight free-in-surge sub-carriage - String tow bridal with spring as proposed by Savitsky 2016 Tests were conducted in regular waves which made it possible to overlay accelerations peaks from a large number of nearly identical hull slams and make direct comparisons of the magnitude and shape of acceleration peaks measured with each towing method. Details of the three towing methods and the pros/cons of each are presented. The string tow method produced significantly cleaner acceleration THE 30th AMERICAN TOWING TANK CONFERENCE WEST BETHESDA, MARYLAND, OCTOBER 2017 2 records. The plots presented make a strong case for this simple and unconventional towing method and may encourage other towing tank facilities to experiment with it in the future.

Assessment of Hydrodynamic Tools for R/V Athena Model 5365 in Calm Water

2017 ◽  
Author(s):  
Anne Fullerton ◽  
Charles Weil ◽  
Evan Lee ◽  
Minyee Jiang ◽  
Fredrick Stern ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Structural Design ◽  
High Speed ◽  
Irregular Waves ◽  
Impact Loads ◽  
Empirical Methods ◽  
Regular Waves ◽  
Hull Form ◽  
Calm Water ◽  
Naval Surface Warfare

Current structural design methods for high speed naval craft rely heavily on empirical methods. Though these methods have been employed reliably for a number of years, it is likely that an unknown level of conservatism exists in the prediction of impact loads. A better physical understanding of the dynamic response of high speed craft in seas would allow for increased structural optimization. The publicly releasable hull form Naval Surface Warfare Center Carderock Division (NSWCCD) Model 5365 (R/V Athena) was chosen to facilitate release of results to various computational teams. Model 5365 was tested in calm water, regular waves, and irregular waves. After reviewing data from the first test in 2014, it was determined that the model should be modified to enable towing from the longitudinal center of gravity. Model 5365 was then modified and re-tested using with added calm water speeds, and additional wave conditions. Calm water results from this test are presented with uncertainty analysis for resistance, heave, and trim.

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