Modeling of the hydrodynamics of subsea floating structures for mollusc offshore cultivation

Bruno Galler Kubelka¹; Claudio Rodrigues Olinto¹; Walter Jesus Paucar Casas²; Waldir Terra Pinto¹

¹ Universidade do Rio Grande - FURG; ² Universidade Federal do Rio Grande do Sul - UFRGS

doi:10.20906/CPS/CILAMCE2017-0938

Resumo

The use of the ocean space for installing aquaculture farms seems to be a sustainable and attractive alternative to the production of protein. However, the installation of such farms near shore may be unappropriated owing to strong environmental loads due to wave and currents. In addition, production residues may cause local pollution, reducing the water quality. Offshore production may be viable as long as the farm can be automatized or operated from shore. Also, farming structure should be placed well below the ocean surface such that wave loading can be significantly reduced. Moreover, the structure should be placed at depths with high concentration of nutrients. This work presents a study of different structure configurations for the culture of molluscs. Mollusc are cultivated in vertical cables or very flexible structures which resemble perforated cylinders, as far the hydrodynamics is concerned. These culture cylinders are hung in flexible structures whose station keeping is achieved through mooring lines. The structural members are considered slender structures and can be modelled by three dimensional cable elements. The hydrodynamic loading is estimated by Morison equation with time dependent drag and lift coefficients to take into account vortex shedding effects. The culture cylinders are modelled as highly flexible second order frame elements. The model is used to simulate some key factors in the design and testing of subsea offshore structures for the development of ocean farming technology.

Palavras-chave: Offshore farming; subsea systems; fluid structure interaction