ABSTRACT
The shape of arti‚cial reefs can be characterized as having a very complicated structure that, in part, facilitates attracting ‚sh by extending the reef’s adhesion area or creating a large cavity. Drag coef‚cients are often used as one of the quantities to technically express this complexity of arti‚cial reefs. For instance, it is well known that as a drag coef‚cient increases, larger eddies are generated downstream of arti‚cial reefs so that plankton gathers more effectively around the reef. On the contrary, if the cavity of arti‚cial reef is larger, the current ¦ow easily passes through the reef and then plankton does not remain near the reef because the drag coef‚cient becomes small. This study contributes to our understanding of arti‚cial reef deployment projects by clarifying the effect that a drag coef‚cient has on an arti‚cial reef when the reef is subject currents of different direction. In addition, we elucidate the extent of vortex occurrence downstream of the arti‚cial reef when this drag coef‚cient differs. The in¦uence of the extent of this vortex was determined by comparing a
CONTENTS
Abstract .......................................................................................................................................... 279 Introduction ....................................................................................................................................280 Materials and Methods .................................................................................................................. 281
Basic Equations ......................................................................................................................... 281 Eddy Energy Dispersion Theory Downstream of the Arti‚cial Reef ...................................... 281 Experimental Conditions for Simulation Model ....................................................................... 283
Veri‚cation Experiments ...................................................................................................... 283 The Change in the Effective Wake Region Using Drag Coef‚cient .................................... 283
Method of Hydraulic Diffusion Experiment .............................................................................284 Results and Discussions .................................................................................................................284
