Investigation on Components of Added Resistance in Short Waves

Abstract

In order to estimate decrease of ship speed in actual seas, it is important to calculate added resistance in waves with accuracy. Especially added resistance in short waves is one of the predominant factors inducing the decrease of speed for a large ship in relation to wave spectrum. Various calculation methods have been proposed for the added resistance in short waves. However those methods are proposed for blunt and low-speed ships, for example, tanker, bulk carrier, etc. Those methods give poor agreement with experimental data for fine and high-speed ships. To improve the estimation method, firstly numerical investigation on the effect of draft and frequency was carried out. Thereafter experiments of wall-sided models with motion fixed were conducted. From these results a new formula is proposed, which gives good agreement with the experimental results.

Verification on the Resistance Test in Waves Using the Actual Sea Model Basin

“…(6) and (7), where I 1 is modified Bessel function of the first kind of order 1, K 1 is modified Bessel function of the second kind of order 1, K is the wave number of regular waves,  is the circular frequency of regular waves and V is the ship speed. The term is originally derived by Ursell 15) and modified by Kuroda et al 16) from numerical and experimental studies.  U is firstly derived by Fujii and Takahashi 13) as an empirical formula and Faltinsen et al 17) derived it as an asymptotic formula for small wave length.…”

A Practical Correction Method for Added Resistance in Waves

“…From experiments of wall-sided models of a fine and a blunt ship the following formula is proposed by Kuroda et al 15) .…”

“…However, for fine ships such as a container ship the calculated value is out of application of the formulas and is poor agreement with the experimental results. Recently Kuroda et al 15) has proposed a correction formula for added resistance due to wave reflection from a point of accuracy. In this paper a practical correction method of added resistance in waves for fine ships is presented.…”

Numerical analysis of added resistance on blunt ships with different bow shapes in short waves

“…In another study, Fujii and Takahashi [4] also derived the semi-empirical formula of the added resistance in short waves by modifying several coefficients in the drift force of a fixed vertical cylinder. Then, the National Maritime Research Institute (NMRI) in Japan proposed an improved expression of Fujii and Takahashi's formula using experimental data [6,17]. Furthermore, Kuroda et al [18] investigated the effect of bow shapes above the waterline for 6500 TEU containerships using a model test, and they proposed the application of a bluntness to determine the coefficients of their empirical formula, which is also known as the NMRI formula.…”

“…Even though many studies on wave-added resistance have been conducted based on experiments [4][5][6][7] and potential-flow solvers [8][9][10][11], computational fluid dynamics (CFD) has also been applied to simulate the added resistance in waves. In the CFD method, it is possible to investigate the details of flow characteristics such as pressure and velocity distribution, even for the violent freesurface flows that interact with a solid body.…”