Page 510 - Practical Design Ships and Floating Structures

Practical Design of Ships and Other Floating Structures 485
You-Sheng Wu, Wei-Cheng Cui and Guo-Jun Zhou (Us)
Q 200 I Elsevier Science Ltd. All rights reserved

ON SCALE EFFECT OF THE RESISTANCE DUE TO STERN
WAVES INCLUDING FORWARD-ORIENTED WAVE BREAKING
JUST BEHIND A TRANSOM STERN

Tadao Yamano', Yoshikazu Kusunoki', Fumiyasu Kuratani', Teturo Ikebuchi2 and Isao Funeno'

'Department of Practical Life Studies, Hyogo University of Teacher Education
942- 1, Shimokume, Yashiro-cho, Kato-gun, Hyogo, 673-1494 Japan
2Fluid Dynamics Research Department, Akashi Technical Institute, Kawasaki Heavy Industries Ltd.
1-1, Kawasaki-cho, Akashi, 673-8666 Japan

ABSTRACT

When a ship with a wide immersed transom stem runs on a deeper draft, forward-oriented wave
breaking often occurs just behind the transom stem. Stem waves in such condition consist of two main
components: the forward-oriented wave breaking and remained following waves. An example of such
stem waves is shown in Figure 4. In our previous papers"*, we have developed a method to treat the
former one and have clarified that it has scale effect and its resistance coefficient decreases with
increase of model ship size. Purpose of this paper is to develop a method to treat the latter ones and
then to clarify scale effect of such stem waves. We have developed a method to estimate resistance due
to the latter ones. After the studies by those methods, we have come to the conclusions: Resistance
increases largely, if the latter ones change to the former one. The latter one resistance coeficient
increases only slightly with increase of model ship size. Resistance coeficient due to such stem waves
is largely affected by the former one and, therefore, decreases with increase of model ship size.

KEYWORDS
Stem waves, Forward-oriented wave breaking, Remained following waves, Resistance, Scale effect

1 INTRODUCTION

Most of the recent container ships have rather wide immersed transom stems to keep necessary
transverse stability with much more containers on deck compared with those of two decades ago.
When such a ship runs on a deeper draft than its design draft, forward-oriented wave breaking with
high turbulence intensity often occurs just behind the transom stem. The phenomenon accompanies
large momentum loss and accordingly generates large hull resistance. Research on the phenomenon is,
therefore, important for energy saving for such ships, Regardinf grevention or decrease of thc
phenomenon, one of the authors has conducted some studies3, 35, . Occurrence mechanism and
characteristics detail of the phenomenon have, however, not yet completely been clarified.