

@mastersthesis {7078,
	title = {The resistance increase of a ship in waves},
	year = {1993},
	note = {C348217},
	school = {Technische Universiteit Delft (The Netherlands)},
	type = {phdDr.},
	address = {Ann Arbor},
	abstract = {In this thesis a detailed investigation is described of the resistance increase of a ship in waves. For a ship sailing on a stormy sea, resistance is increased due to contributions from a whole range of sources: waves, wind, rudder drag, and drift angle, as a result of which often the speed is reduced. One of the most important contributions to the resistance increase stems from the forces of the waves on the ship. This may either cause a speed loss or increased fuel consumption. It can be shown that the resistance increase due to waves, or the {\textquoteright}wave added resistance{\textquoteright}, is predominantly of potential origin, the frictional contribution being small. This opens up the possibility of invoking the Froude scaling law to convert experimental data from model scale to the full ship scale, and it allows the use of potential theory to describe the behaviour of the flow. It was hypothesized that the wave added resistance is for the most part the result of the relative water motions predominantly at the bow; and the study had the objective to validate this hypothesis. An extensive suite of model test programs was carried out to obtain insight into the behaviour of the flow, the pressures and the free surface around a ship model in motion in waves. A mathematical model based on linear potential theory was set up to describe the observed effects. Correlation computations were made for 4 hull forms, a slender and a beamy Wigley hull, a cargo ship and a frigate. The key aspects of the study are the analysis of the relative water motion at the bow in which a strong interaction between the stationary and the non-stationary flow field was discovered, leading to the definition of the {\textquoteright}dynamic swell-up{\textquoteright}. This {\textquoteright}swell-up{\textquoteright} is an effect brought about by the influence of local draft on the steady bow wave, and it was shown to be remarkably independent of frequency. The interaction was also shown to exist deeper in the fluid. The dynamic variations about the steady mean value contained a significant contribution of the swell-up. In the global sense the upper part of the bow of the model was found to contribute the greater part of the extra resistance, the lower bow and the stern making only minor contributions. Both the model experiments and the mathematical model based computations supported the hypothesis. (Abstract shortened by UMI.)},
	keywords = {0547:Ocean engineering, Applied sciences, Ocean engineering},
	url = {http://search.proquest.com/docview/304113712?accountid=14270},
	author = {Blok, Jan Jacobus}
}
