RIASSUNTO
ABSTRACT:
In this paper, the motion characteristics of some kinds of fishery cages are analyzed by experimental and numerical method. Circular and rectangular types are considered to investigate the difference of the hydrodynamic behaviors in waves and to find out the effective shape of the frame in terms of the reduction of the motion which alleviates the stress put on the fish. The models of the two cages were made of high density PE pipe and the experiment was carried out in the ocean engineering basin at KRISOIKORDI. A numerical code developed by using HOBEM is used to calculate the hydrodynamic coefficients and the motion responses.
INTRODUCTION
The aquaculture plays an increasingly important role in the fish production industry in Korea. For about two decades, the improvement in the aquaculture hasn’t met the increasing demand for fish as a food. The protected coastal regions, so called near shore, such as harbor, in which artificial or natural shields make environment less affected by the off-shore weather, have been so spoiled that they may not be suitable for cultivating fish. The red tide also threatens the fishes in the cage. Therefore, an increased activity is expected to force a move to less sheltered sites where wave effects leading to motions in the cage and the loads in the mooring lines are expected to become more important(Hugunen, 1997). These cages require a mooring system to maintain their position on site and allow their survival at inclement weather and seastate. In the operation condition, the motion response properties are the more important factor for the cages to do their primary role; protecting the fishes to give them a comfortable room. Thereafter, a prototype could be designed by the numerical model and experiment to tolerate the severe environmental conditions.