Analysis and Modelling of Ship Manoeuvring Simulation in Landslide-Generated Waves

The geological conditions of the Three Gorges Reservoir Region are complex and changing, and large- and medium-sized landslides are widely distributed. When a high-speed moving landslide enters the water, the water is significantly disturbed, and a landslide-generated wave will be formed, which will spread along the upstream and downstream of the river, causing significant threats and destruction to the hydraulic structures and the navigation of ships. Based on the typical rock landslide parameters and fracture development, we establish a three-dimensional physics experimental model of the bending section of the landslide-generated wave in the Three Gorges Reservoir Region. This paper primarily studies the variation law of the first wave height of landslide-generated waves with the width, height, and water entry velocity of the landslide body and then provides an empirical formula for the first wave height of landslide-generated waves in the curved section of the Three Gorges Reservoir Region. The ship rolling motion equation in the landslide-generated water area is analysed and established systematically. Additionally, the ship manoeuvring motion model in the landslide-generated water area is built. This paper explains the variation characteristics of ship turning tracks at different sailing speeds and sailing positions and proposes a basis to determine the navigation safety of ships in this area, thus providing new theoretical and technical support for the risk assessment of navigation of ships in the reservoir area.

A COMPARISON OF EXPERIMENTAL AND NUMERICAL BEHAVIOUR CHARACTERISTICS OF A SHIP ENTERING A LOCK USING BENCHMARK TEST DATA

This paper discusses several papers that were presented at the 3rd International Conference on Ship Manoeuvring in Shallow and Confined Water, which had a non-exclusive focus on Ship Behaviour in Locks. For this conference, experimental model test data obtained at Flanders Hydraulics Research had been made public and researchers were encouraged to compare numerical with experimental results [1]. Data of benchmark tests carried out both with self- propelled and captive models were used by researchers for comparison with various numerical tools. The objective of this paper is to give a selected overview of how accurately numerical tools are presently able to predict the hydrodynamic forces that occur on ships approaching locks. Based on this, the paper concludes that experiments and numerical tools complement each other.

EXPERIMENTAL AND NUMERICAL STUDY OF THE EFFECT OF A PIER ON SHIP TRAJECTORIES IN CURRENTS

A study is presented of the effect of a pier on ship trajectories in currents. The current flow field around the pier is investigated. Experiments on ship manoeuvring and drift motion in the vicinity of a rectangular pier were carried out in a tank. Different current velocities and current angles were taken into account. The characteristics of the deviations of the ship trajectories from the initial course around the pier are investigated. Experimental findings indicate that the minimum required distance for safety navigation becomes larger with an increase of the current velocity. To obtain the details of continuous three-dimensional flow field around a pier, numerical simulation based on CFD calculations is conducted. The validity of the numerical simulation is demonstrated by comparison with experimental results.

Identification of Ship Hydrodynamic Derivatives Based on LS-SVM with Wavelet Threshold Denoising

Nowadays, system-based simulation is one of the main methods for ship manoeuvring prediction. Great efforts are usually devoted to the determination of hydrodynamic derivatives as required for the mathematical models used for such methods. System identification methods can be applied to determine hydrodynamic derivatives. The purpose of this work is to present a parameter identification study based on least-squares support-vector machines (LS-SVMs) to obtain hydrodynamic derivatives for an Abkowitz-type model. An approach for constructing training data is used to reduce parameter drift. In addition, wavelet threshold denoising is applied to filter out the noise from the sample data during data pre-processing. Most of the resulting derivatives are very close to the original ones—especially for linear derivatives. Although the errors of high-order derivatives seem large, the final predicted results of the turning circle and zigzag manoeuvres agree pretty well with the reference ones. This indicates that the used methods are effective in obtaining manoeuvring hydrodynamic derivatives.

Maritime navigational assistance by visual augmentation

Several types of equipment have been developed over the years to assist ship operators with their tasks. Nowadays, navigational equipment typically provides an enormous volume of information. Thus, there is a corresponding need for efficiency in how such information is presented to ship operators. Augmented reality (AR) systems are being investigated for such efficient presentation of typical navigational information. The present work is particularly interested in an AR architecture commonly referred as monitor augmented reality (MAR). In this context, the development of MAR systems is briefly summarised. The projection of three-dimensional elements into a camera scene is presented. Potential visual assets are proposed and exemplified with videos from a ship manoeuvring simulator and a real experiment. Enhanced scenes combining pertinent virtual elements are shown exemplifying potential assistance applications. The authors mean to contribute to the popularisation of MAR systems in maritime environments. Further research is suggested to define optimal combinations of visual elements for alternative maritime navigation scenarios. Note that there are still many challenges for the deployment of MAR tools in typical maritime operations.