RIASSUNTO
ABSTRACT
An experiment on cubical submerged structure like artificial fish reef is conducted to determine the flow field and mechanisms of local scouring and resultant embedment. Moreover, a numerical scheme for three-dimensional flow field computation including- the vortex formations is developed. Based on the results, the pertinent characteristics of flow field arc discussed in relation to the vortex 1bnnations. For movable bed, the vortex formation and the steady outward flows from the structure are very significant in local scouring which is directly responsible in the embedment of the structure. The relationships between the flow field due to variation of KC and Re numbers with the maximum values of scouring depth and embedment are discussed. Lastly, the flow patterns and vortex formation are well evaluated by the numerical computation; thus, the characteristics of the computed flow field explain well file generation mechanisms of local sourcing.
INTRODUCTION
Artificial fish reefs are today a well established fishery enchancement technique that is being- practiced around the world. For the past centuries, marine anglers have used artificial fish reefs to enhance their fishing efforts by placing rocks in bottom bed. Historical records show that the placement of rocks to enhance kelp production has been the common practice of Japanese fishermen since the late seventeenth century (Aomori Prefecture. 1980). However, during storms and high waves, most of these rocks are moved of severely embedded: thus, many of the attached organisms are crushed and the sheltering of other living organisms in the zone of enhancement is greatly disturbed. Because of the poor stability and very low durability'' of-these kinds of fishing reefs, it is more economical and efficient in the long run to build artificial reels with specially designed structures and durable materials.