scholarly journals A Theoretical Study of Hydrodynamic Derivatives on Ship Maneuvering in Restricted Water

1988 ◽  
Vol 1988 (163) ◽  
pp. 119-129
Author(s):  
Hironori Yasukawa
Keyword(s):  
Theoretical Study ◽  
Ship Maneuvering ◽  
Hydrodynamic Derivatives

Effects of Hull and Control Surface Roughness on Ship Maneuvering

2020 ◽  
pp. 1-10
Author(s):  
John C. Daidola
Keyword(s):  
Surface Roughness ◽  
Equations Of Motion ◽  
Control Surface ◽  
Ship Maneuvering ◽  
Single Screw ◽  
Operation And Maintenance ◽  
Hydrodynamic Derivatives ◽  
Turning Maneuver ◽  
And Control ◽  
Surface Vessel

The effects of hull roughness on ship maneuvering characteristics are investigated. The hydrodynamic derivatives in the equations of motion for surface vessel maneuvering are modified to incorporate roughness of the hull and rudder. Vessel lifetime roughness profiles are postulated based on construction, coatings, operation, and maintenance for a vessel life of 25 years. These are then applied to the turning maneuver for single screw cargo ships with block coefficients from .60 to .80. The implications for naval missions are discussed.

System Identification of Abkowitz Model for Ship Maneuvering Motion Based on ε-Support Vector Regression

2019 ◽  
Author(s):  
B. Liu ◽  
Y. Jin ◽  
A. R. Magee ◽  
L. J. Yiew ◽  
S. Zhang
Keyword(s):  
System Identification ◽  
White Noise ◽  
Support Vector Regression ◽  
Gaussian White Noise ◽  
Support Vector ◽  
Ship Maneuvering ◽  
Model Match ◽  
Hydrodynamic Derivatives ◽  
Batch Learning ◽  
Predicted Model

Abstract System identification is crucial to predict the maneuverability of the ship. In this work, ε-support vector regression (ε-SVR) is implemented to identify hydrodynamic derivatives of Abkowitz maneuver model. A proposed technique, batch learning, is implemented with the addition of Gaussian white noise to reconstruct the samples and alleviate the parameter drift in the system identification of the ship maneuvering model. The predicted results are compared with results obtained from Planar Motion Mechanism (PMM) test. Standard maneuvers, 35° turning circle, 10°/10° and 20°/20° zigzags, are simulated and compared with the predicted model by ε-SVR. The presented results show that the proposed batch learning technique with Gaussian white noise is an effective technique, which improves the accuracy and robustness of ε-SVR in system identification. The results obtained from the predicted model match well with the those obtained from PMM results, which shows its excellent generalization performance. The developed model is applied to understand control requirements for vessels under different conditions.

Time Domain Simulations of Ship Maneuvering and Roll Motion in Regular Waves Based on a Hybrid Method

2019 ◽  
Author(s):  
Chengqian Ma ◽  
Ning Ma ◽  
Xiechong Gu
Keyword(s):  
Time Domain ◽  
Hybrid Approach ◽  
Wave Force ◽  
Domain Model ◽  
Viscous Force ◽  
Scale Model ◽  
Regular Waves ◽  
Ship Maneuvering ◽  
Frequency Wave ◽  
Hydrodynamic Derivatives

Abstract Ship maneuvering performance and rolling in waves under complicated environmental conditions are of significant importance for safety and economic reasons. The existing methods for predicting the maneuvering in adverse sea conditions can be categorized into unified two-time scale model, hybrid approach and CFD method. However, traditional potential methods rely tightly on ship viscous force data from test results, and CFD methods of free running ship require large computational resources consumption. In this paper, a 4-DOF (surge, sway, yaw and roll) model based on MMG method considering the wave effect is established to predict the trajectory and rolling motion with better time efficiency. The 1st order wave force and mean 2nd order drift force in this time-domain model are calculated by the 3D panel method and Cummins impose response function. Instead of model experiments, the hydrodynamic derivatives in the maneuvering model can be calculated by RANS-based numerical simulations of the Planar Motion Mechanism (PMM) test in calm water. Verification for grid convergence is also conducted according to state-of-the-art study. The predicted turning trajectory and rolling angle of the S175 containership in regular waves using CFD results show better agreement with experiment data than empirical formula results. Furthermore, it has been demonstrated that this model is also capable of predicting the ship motion in regular waves with practical accuracy. And the effects of the wave frequency, wave height are investigated consequently base on numerical simulation results.

Parametric Identification of Abkowitz Model for Ship Maneuvering Motion by Using Partial Least Squares Regression

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Yin Jian-Chuan ◽  
Zou Zao-Jian ◽  
Xu Feng
Keyword(s):  
Least Squares ◽  
Partial Least Squares ◽  
Parametric Identification ◽  
Small Sample ◽  
High Dimensionality ◽  
Pls Regression ◽  
Ship Maneuvering ◽  
Processing Data ◽  
Hydrodynamic Derivatives ◽  
Maneuvering Motion

Partial least squares (PLS) regression is used for identifying the hydrodynamic derivatives in the Abkowitz model for ship maneuvering motion. To identify the dynamic characteristics in ship maneuvering motion, the derivatives of hydrodynamic model's outputs are set as the target output of the PLS identification model. To verify the effectiveness of PLS parametric identification method in processing data with high dimensionality and heavy multicollinearity, the identified results of the hydrodynamic derivatives from the simulated 20 deg/20 deg zigzag test are compared with the planar motion mechanism (PMM) test results. The performance of PLS regression is also compared with that of the conventional least squares (LS) regression using the same dataset. Simulation results show the satisfactory identification and generalization performances of PLS regression and its superiority in comparison with the LS method, which demonstrates its capability in processing measurement data with high dimensionality and heavy multicollinearity, especially in processing data with small sample size.

Parameter Identification of Ship Maneuvering Model Based on Support Vector Machines and Particle Swarm Optimization

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Weilin Luo ◽  
C. Guedes Soares ◽  
Zaojian Zou
Keyword(s):  
Particle Swarm Optimization ◽  
Support Vector Machines ◽  
Difference Method ◽  
Particle Swarm ◽  
Support Vector ◽  
Ship Maneuvering ◽  
Swarm Optimization ◽  
Hydrodynamic Derivatives ◽  
Vector Machines ◽  
Maneuvering Motion

Combined with the free-running model tests of KVLCC ship, the system identification (SI) based on support vector machines (SVM) is proposed for the prediction of ship maneuvering motion. The hydrodynamic derivatives in an Abkowitz model are determined by the Lagrangian factors and the support vectors in the SVM regression model. To obtain the optimized structural factors in SVM, particle swarm optimization (PSO) is incorporated into SVM. To diminish the drift of hydrodynamic derivatives after regression, a difference method is adopted to reconstruct the training samples before identification. The validity of the difference method is verified by correlation analysis. Based on the Abkowitz mathematical model, the simulation of ship maneuvering motion is conducted. Comparison between the predicted results and the test results demonstrates the validity of the proposed methods in this paper.

scholarly journals Numerical Estimation of Hull Hydrodynamic Derivatives in Ship Maneuvering Prediction

2021 ◽  
Vol 28 (2) ◽  
pp. 46-53
Author(s):  
Radosław Kołodziej ◽  
Paweł Hoffmann
Keyword(s):  
Model Tests ◽  
Circular Motion ◽  
Computational Method ◽  
Design Stage ◽  
Hydrodynamic Characteristics ◽  
Ship Maneuvering ◽  
Hydrodynamic Derivatives ◽  
Captive Model Tests ◽  
Ship Maneuverability ◽  
Free Running

Abstract Prediction of the maneuvering characteristics of a ship at the design stage can be done by means of model tests, computational simulations or a combination of both. The model tests can be realized as a direct simulation of the standard maneuvers with the free running model, which gives the most accurate results but is also the least affordable, as it requires a very large tank or natural lake, as well as the complex equipment of the model. Alternatively, a captive model test can be used to identify the hydrodynamic characteristics of the hull, which can be used to simulate the standard maneuvers with the use of dedicated software. Two types of captive model tests are distinguished: circular motion tests (CMT) and planar motion mechanism tests (PMM). The paper presents an attempt to develop a computational method for ship maneuverability prediction in which the hydrodynamic characteristics of the hull are identified by means of computational fluid dynamics (CFD). The CFD analyses presented here directly simulate the circular motion test. The resulting hull characteristics are verified against the available literature data, and the results of the simulations are verified against the results of free running model tests. Reasonable agreement shows the large potential of the proposed method.

Numerical Investigation on the Influence of Froude Number on the Hydrodynamic Derivatives of a Container Ship

2016 ◽  
Author(s):  
Rameesha Thayale Veedu ◽  
Parameswaran Krishnankutty
Keyword(s):  
Hydrodynamic Characteristics ◽  
Container Ship ◽  
Trajectory Prediction ◽  
Ship Maneuvering ◽  
Approach Speed ◽  
Hydrodynamic Derivatives ◽  
Planar Motion Mechanism ◽  
Early Design Stages ◽  
Derivatives Of ◽  
Vessel Speed

Evaluation of maneuverability of a ship at the early design stages is necessary for ensuring safety of its voyage. IMO recommends the test speed or approach speed for the maneuvering predictions as 90–100% of the service speed of the vessel. The confined model tests for ship maneuvering assessment are usually conducted at low speeds and the hydrodynamic derivatives obtained from these tests are used in the equation of motion even when vessel operates at much higher speeds. But the hydrodynamic derivatives and consequently the trajectory predicted using these derivatives differ substantially from the actual maneuvering conditions. Hence the dependency of the derivatives on vessel speed needs to be understood properly to get the correct estimate of the vessel trajectory prediction. This paper investigates the effect of vessel speed (Fn) on hydrodynamic characteristics of a container ship. Straightline test and horizontal planar motion mechanism (HPMM) tests are conducted for a container ship model for different speeds in a CFD environment.

A Hybrid Method for Predicting Ship Maneuverability in Regular Waves

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Tianlong Mei ◽  
Yi Liu ◽  
Manasés Tello Ruiz ◽  
Evert Lataire ◽  
Marc Vantorre ◽  
...  
Keyword(s):  
Hybrid Method ◽  
Panel Method ◽  
Regular Waves ◽  
Ship Maneuvering ◽  
Wave Drift ◽  
Hydrodynamic Derivatives ◽  
Ship Maneuverability ◽  
Wave Drift Forces ◽  
Maneuvering Motion ◽  
Drift Forces

Abstract Traditionally, ship maneuvering is analyzed under calm water condition. In a more realistic scenario, such as a ship sailing in waves, the importance of taking the wave effects into account should be stressed. In this context, this paper proposes a hybrid method for predicting ship maneuverability in regular waves by combining a potential flow theory based panel method and a Reynolds-averaged Navier–Stokes (RANS)-based computational fluid dynamics method. The mean wave drift forces are evaluated by applying a three-dimensional time-domain higher-order Rankine panel method, which takes the effects of ship's forward speed and lateral speed into consideration. The hull-related hydrodynamic derivatives in the equations of ship maneuvering motion are determined by using a RANS solver based on the double-body model. Then, the two-time scale method is applied to predict ship maneuvering in regular waves by integrating the seakeeping model in a three degrees-of-freedom MMG model for ship maneuvering motion. The numerical results of a laterally drifting S175 container ship, including the wave-induced motions, wave drift forces, and turning trajectories in regular waves, are presented and compared with the available experimental data in literature. The results show that the proposed hybrid method can be used for qualitatively predicting ship maneuvering behavior in regular waves.

Numerical Prediction of Ship Hydrodynamic Derivatives in Close Proximity to a Vertical Bank and Maneuvering Stability Analysis

2016 ◽  
Author(s):  
Han Liu ◽  
Ning Ma ◽  
Xiechong Gu
Keyword(s):  
Lateral Force ◽  
Ship Maneuvering ◽  
Directional Stability ◽  
Bank Effect ◽  
Hydrodynamic Derivatives ◽  
Captive Model Tests ◽  
Close Proximity ◽  
Derivatives Of ◽  
Yaw Moment ◽  
Water Depths

As bank effect has a remarkable influence on the maneuverability of a ship proceeding close to a vertical bank, the assessment of ship maneuvering stability is of great importance. The hydrodynamic derivatives of a ship can reflect the change of the ship’s maneuverability and they are determined with the method of planar motion mechanism (PMM) tests. This paper presents a numerical way to simulate the PMM captive model tests for the ship KVLCC2. A general purpose viscous flow solver was adopted to solve unsteady Reynolds averaged Navier Stokes (RANS) equations in conjunction with a RNG k-ε turbulence model. A hybrid dynamic mesh technique is developed to update the mesh volume around the ship hull when the ship is undertaking pure yaw motions and it turns out efficient and effective to solve the limitation of small ship-bank distance to the mesh configuration and remeshing.. The numerical simulations and the accuracy of the numerical method was validated in comparison with the results of PMM tests in a circulating water channel. Then a series of distances between ship and bank together with different water depths were set for simulating the PMM tests of the KVLCC2 model in proximity to a vertical bank. The first order hydrodynamic derivatives of the ship were analyzed from the time history of lateral force and yaw moment according to the multiple-run simulating procedure. The values of derivatives in different lateral proximities to the bank and variant water depths were compared and it showed some favorable trends for predicting the ship’s maneuverability in the restricted waterways. For example, the influence of velocity derivatives on lateral force reduces while that of velocity derivatives on yaw moment strengthens and this is partly due to the suction force and bow-out moment caused by bank wall effect. The straight line stability and directional stability in terms of the calculated hydrodynamic derivatives were also discussed based on the MMG model for ship maneuvering. Results indicate that the ship is inherently unstable without control and the enhancement of bank effect makes the condition even worse. Moreover, a stable or unstable zone of PD controller parameters focusing on the directional stability was illustrated and setting the values of controller parameters in the range of “Control with high sensitivity” is recommended for cases of the ship navigating in very close proximity to a bank.

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