Abstract

The vessels at outer anchorage are exposed to the influence of a complex system of waves. This system is formed by the incident and diffracted waves. In order to examine characteristics of a wave field around the vessel, which floats idling at outer anchorage, we solved two problems. The first problem is determining the velocity potential of diffracted wave motion, caused by the incidence at arbitrary angle of regular waves with small amplitude to a stationary vessel under conditions of shallow water. The solution is executed by the matched asymptotic expansion method (MAEM). The region filled with fluid is conditionally divided into the internal and external zones. In both zones, separate boundary problems are stated, and they are considerably simpler than the initial boundary problem for the entire region. The solutions of the problems are asymptotically merged at the border of zones. The second problem is defining the characteristics of waves near a vessel. From the expression for a speed potential we derived the equation of perturbed free surface. The calculations are conducted of the waves’ amplitudes in the assigned points around the vessel. The variable parameters are the depth of water area, wavelength and a course angle of waves. The examples of wave fields are given. Determining the characteristics of a wave field transformed by the vessel is important for planning the operation of auxiliary ships (tugboats, bunkering vessels, pilot and port roads boats, as well as oil/garbage collector boats and boom crafts). This work is connected with the safety of traffic in the open sea (transfer of people and loads from one vessel to another) and with ecological safety (elimination of oil and petroleum spills). Wave height is the limiting factor for operating the auxiliary vessels, which is why determining it properly is a necessary task.

Highlights

  • In most of the ports of the Black and Azov Seas, large-capacity tankers and bulk carriers, as well as some passenger vessels, have to be loaded, unloaded or fuelled outside of the ports protected by water basins

  • The ships that are docked on outer anchorage are under the influence of the rough sea and, at the same time, they prevent the propagation of waves

  • The height of waves in specific points of the field depends on the location of points around the ship

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Summary

Introduction

In most of the ports of the Black and Azov Seas, large-capacity tankers and bulk carriers, as well as some passenger vessels, have to be loaded, unloaded or fuelled outside of the ports protected by water basins. A diffraction problem is tackled rarely, since overcoming the difficulties associated with the practical evaluation of characteristics of a wave field around the body of a vessel requires special processing of the computing aspects of the obtained theoretical results. Characteristics of the waves around the vessel, which is anchored at the open port roads, are to be considered when planning the operation of auxiliary ships. Auxiliary vessels are tugs, bunkering vessels, pilot and harbor boats, as well as oil/garbage collector boats and boom crafts. The work of these vessels is related to safe navigation (transfer of people and cargo from one ship to another) and environmental safety (elimination of oil and petroleum spills). Determining the transformation of waves on outer anchorage is necessary for their safe operation, which is why this is a relevant task

Literature review and problem statement
The aim and tasks of the study
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