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 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.

Some Extensions of the Classical Approach to Strip Theory of Ship Motions, Including the Calculation of Mean Added Forces and Moments

1978 ◽  
Vol 22 (01) ◽  
pp. 1-19 ◽  
Author(s):  
Theodore A. Loukakis ◽  
Paul D. Scfavounos
Keyword(s):  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Dynamical Theory ◽  
Forced Oscillations ◽  
Ship Motions ◽  
Regular Waves ◽  
Strip Theory ◽  
Calm Water ◽  
Exciting Forces ◽  
New Formulation

The application of the dynamical theory to the problem of a ship moving with constant forward speed on a free surface has been extended to include the exciting forces in oblique regular waves. As a result, it has become possible to derive a new formulation for the equations of motion, for a ship moving with five degrees of freedom. The application of the same theory has yielded formulas for the calculation of the mean added resistance and drift force in oblique regular waves and the calculation of all mean forces and moments for the forced oscillations of a ship in calm water.

A New Technique for Testing a Sailing Yacht in Waves

1991 ◽  
Author(s):  
G. K. Kapsenberg
Keyword(s):  
Degrees Of Freedom ◽  
Water Resistance ◽  
Ship Motions ◽  
Added Resistance ◽  
Regular Waves ◽  
Six Degrees Of Freedom ◽  
Resistance Increase ◽  
Calm Water ◽  
Sailing Yacht ◽  
A New Technique

A new experimental technique is presented to test sailing yachts in waves. The method is suitable for the investigation of ship motions in all six degrees of freedom and added resistance for the close hauled condition. Measurements can be made both in regular waves and in irregular seas. The technique has been tried out on a model of a 12-Meter class yacht and showed a resistance increase for the yacht sailing to windward in a wind generated sea of 90% of the calm water resistance.

Research on HOV Space Motion Mathematical Model

2013 ◽  
Vol 706-708 ◽  
pp. 1795-1798
Author(s):  
Feng Liu ◽  
Duan Feng Han
Keyword(s):  
Mathematical Model ◽  
Degrees Of Freedom ◽  
Motion Simulation ◽  
Simulation Research ◽  
Six Degrees Of Freedom ◽  
Object Based ◽  
Space Motion ◽  
Motion Characteristics ◽  
Important Basis ◽  
Maneuvering Motion

Human Occupied Vehicle（HOV） is a typical system which is characterized by high nonlinearities,couplings,uncertainties and multi-stance 3D movement.It requires quite exact description and dynamic simulation research .In general,it is difficult to get precise dynamic model. this paper regards a certain HOV as research object, based on the HOV six degrees of freedom equations motion, simplified the present mathematical model of HOV space maneuvering motion , developed HOV motion simulation program by Matlab software,simulation were taken by choosing several typical motion states,the simulation results show that the HOV space motion mathematical model can reflect the HOV motion characteristics,also provide important basis for the design of HOV motion control system.

Research on Network Communication Model of Intelligent Ship Handling Simulator

2011 ◽  
Vol 97-98 ◽  
pp. 787-793 ◽  
Author(s):  
Shen Hua Yang ◽  
Guo Quan Chen ◽  
Xing Hua Wang ◽  
Yue Bin Yang
Keyword(s):  
Mathematical Model ◽  
Degrees Of Freedom ◽  
Communication Process ◽  
Network Communication ◽  
Communication Model ◽  
Test Results ◽  
Six Degrees Of Freedom ◽  
Model Based ◽  
Hydraulic Servo ◽  
Ship Handling

Due to the target ship in the traditional ship handling simulator have not the ability to give way to other ships automatically to avoid collision, this paper put forward a new idea that bringing the hydraulic servo platform, six degrees of freedom ship mathematical model, the actual traffic flow, researching achievement of automatic anti-collision in research of the new pattern ship handling simulator, and successfully develop the Intelligent Ship Handling Simulator(ISHS for short). The paper focuse on the research on the network communication model of ISHS. We took the entire simulator system as three relatively independent networks, proposed a framework of communication network that combined IOCP model based on TCP with blocking model based on UDP, and gave the communication process and protocols of system. Test results indicate that this is an effective way to improve the ownship capacity of ship handling simulator and meet the need of multi-ownship configuration of desktop system of ship handling simulator.

General Mathematical Model of Multi-Arm Cooperating Robots With Elastic Interconnection at the Contact

1997 ◽  
Vol 119 (4) ◽  
pp. 707-717 ◽  
Author(s):  
Milovan Z˘ivanovic´ ◽  
Miomir Vukobratovic´
Keyword(s):  
Mathematical Model ◽  
Degrees Of Freedom ◽  
Dynamic Environment ◽  
Six Degrees Of Freedom ◽  
General Mathematical Model ◽  
Cooperating Robots ◽  
Six Degree Of Freedom ◽  
Physical Phenomena ◽  
First Time ◽  
Object Dynamic

The procedure of modeling and the complete general form mathematical model of manipulators with six degrees of freedom in cooperative work are presented in the paper, together with the solution of undefiniteness problem with respect to force distribution. For the first time, a system of active spatial six-degree-of-freedom mechanisms elastically interconnected with the object (dynamic environment) is modeled. The reason for the emergence of the undefiniteness problem with respect to force is explained and the procedure for solving this problem given. Unlike the approaches given in the available literature, the undefiniteness problem with respect to force is solved in accordance with physical phenomena. The modeling procedure is illustrated by a simplified example.

Model Tests of a Caisson in Wet Towing for Assessing Resistance and Stability in Calm Water and Waves

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Chang-Wook Park ◽  
Jeonghwa Seo ◽  
Shin Hyung Rhee
Keyword(s):  
Degrees Of Freedom ◽  
Model Tests ◽  
Added Resistance ◽  
Power Requirement ◽  
Effective Power ◽  
Six Degrees Of Freedom ◽  
Calm Water ◽  
Improved Stability ◽  
Scale Ratio ◽  
The Stability

A series of model tests of a caisson in wet towing were conducted in a towing tank to assess the stability and effective power requirement in calm water and head sea conditions. The scale ratio of the model was 1/30, and the model-length-based Froude number in the tests ranged from 0.061 to 0.122, which is equivalent to 2 and 4 knots in the full scale, respectively. During the towing of the model, tension on the towline and six-degrees-of-freedom (6DOF) motion of the model were measured. Under the calm water condition, the effects of towing speed, draft, and initial trim variation on the towing stability and effective power were investigated. Initial trim improved stability and reduced required towing power. In head seas, effective power and towing stability were changed with the wavelength. It increased as the wavelength became longer, but the added resistance in long waves also stabilized the model with reduced yaw motion.

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.

Numerical Simulation of Damaged Ship’s Motion in Beam Waves

2019 ◽  
Author(s):  
Qing Wang ◽  
Xuanshu Chen ◽  
Liwei Liu ◽  
Xianzhou Wang ◽  
MingJing Liu
Keyword(s):  
Degrees Of Freedom ◽  
Body Motion ◽  
Ship Motions ◽  
Rans Equations ◽  
Six Degrees Of Freedom ◽  
Calm Water ◽  
Unsteady Simulation ◽  
Ship Hydrodynamic ◽  
Physical Phenomena ◽  
Damaged Ship

Abstract The dangerous situation caused by the breakage of the ship will pose a serious threat to crew and ship safety. If the ship’s liquid cargo or fuel leaks, it will cause serious damage to the marine environment. If damage occurs accompanied by roll and other motions, it may cause more dangerous consequences. It is an important issue to study the damaged ship in time-domain. In this paper, the motions of the damaged DTMB 5512 in calm water and regular beam waves are studied numerically. The ship motions are analyzed through CFD methods, which are acknowledged as a reliable approach to simulate and analyze these complex physical phenomena. An in-house CFD (computational fluid dynamics) code HUST-Ship (Hydrodynamic Unsteady Simulation Technology for Ship) is used for solving RANS equations coupled with six degrees of freedom (6DOF) solid body motion equations. RANS equations discretized by finite difference method and solved by PISO algorithm. Level set was used for free surface simulation. The dynamic behavior of model was observed in both intact and damaged condition. The heave, roll and pitch amplitudes of the damaged ship were studied in calm water and beam wave of three wavelengths.

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.

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