Experimental Study of Wave Forces on Vertical Cylinders in Shallow Waters

Author(s):  
Rujian Ma ◽  
Guixi Li ◽  
Dong Zhao ◽  
Jungang Wang

An experimental study of wave forces on the vertical cylinders in shallow waters was carried out in a wave channel. The wave parameters, wave forces and wave pressures are measured and studied in the paper. The study indicates that the distribution of wave pressures of the shallow water waves can be described by an exponential function with respect to water depth. The maximum surface elevation for shallow water waves can be estimated using the significant wave height. The wave pressure around circumference can be expressed as a simple form of cosine function. An experimental formula for the calculation of wave forces on vertical cylinders is proposed. As compared with test data, the predicted wave forces showed good agreement and high reliability. The calculated wave forces by different wave theories are less than those of the proposed method. Therefore, the wave force calculation method for shallow water waves should be modified for engneering applications.

Author(s):  
Manases Tello Ruiz ◽  
Marc Mansuy ◽  
Guillaume Delefortrie ◽  
Marc Vantorre

When approaching or leaving a port a ship often needs to perform manoeuvres in the presence of waves. At the same time the water depth is still limited for deep drafted vessels. For manoeuvring simulation purposes this requires a manoeuvring model which includes phenomena such as short crested waves and squat effects. The present paper addresses the manoeuvring problem in shallow water waves numerically and experimentally. The numerical study is conducted by means of potential theory, incorporating first and second order exciting wave forces, and their superposition to the calm water manoeuvring models. The applicability of such an approach is also investigated. The experimental work has been conducted at Flanders Hydraulics Research (in cooperation with Ghent University) with a scale model of an ultra large container vessel. Captive model tests comprise harmonic yaw tests and steady straight line tests with and without waves, at different forward speeds, wave frequencies and amplitudes, in head and following waves. Waves are chosen to represent conditions commonly met by ships in the Belgian coastal zone of the North Sea.


Author(s):  
Shin-ichi AOKI ◽  
Tomoki HAMANO ◽  
Taishi NAKAYAMA ◽  
Eiichi OKETANI ◽  
Takahiro HIRAMATSU ◽  
...  

2021 ◽  
Vol 126 (1) ◽  
Author(s):  
Kenan Šehić ◽  
Henrik Bredmose ◽  
John D. Sørensen ◽  
Mirza Karamehmedović

2014 ◽  
Vol 66 (2) ◽  
Author(s):  
Mohammadreza Fathi Kazerooni ◽  
Mohammad Saeed Seif

One of the phenomena restricting the tanker navigation in shallow waters is reduction of under keel clearance in the terms of sinkage and dynamic trim that is called squatting. According to the complexity of flow around ship hull, one of the best methods to predict the ship squat is experimental approach based on model tests in the towing tank. In this study model tests for tanker ship model had been held in the towing tank and squat of the model are measured and analyzed. Based on experimental results suitable formulae for prediction of these types of ship squat in fairways are obtained.


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