In this paper, the characteristics of the flow field inside the deep-sea aquaculture cage in the sea and the effects of different oxygen supply methods on the diffusion of micro-nano bubbles and the distribution of feed particles were studied by numerical simulation. The results show that the cage net can reduce the influence of external waves and currents on the internal flow field of the cage. When the wavelength is large, the influence of waves on the internal flow field of the cage cannot be ignored. When the total oxygen injected into the cage is the same, the diffusion of oxygen in the form of micro-nano bubbles inside the cage will be affected by the method of oxygen supply, waves and currents. The injection of oxygen can promote the diffusion of fish feed inside the cage, and also increases the residence time of fish feed inside the cage, so it can improve the breeding environment. The results of this paper can provide technical support for the selection of oxygenation method and feeding method in the deep-sea aquaculture cage.
China has rich marine fishery resources, and its aquaculture production accounts for about 70% of the total of the world. China is the world's largest producer of fishery and trader of aquatic products. However, with the increase in people's demand for aquatic products, resulting in over-exploitation of fishery resources and less space for offshore aquaculture (Naylor R et al.,2005), moreover, a large amount of residual feeding and fish feces produced by cage culture are lost to the sea, which seriously affects the offshore mariculture environment (R.S.S. Wu,1995). This results in frequent occurrence of fish diseases, decline of major economic fish resources, and almost extinction of some species in some waters. Deep-sea cage culture can increase the output of aquatic products and relieve the pressure of offshore aquaculture. Therefore, in order to achieve the effect of improving fish quality and reducing environmental impact of deep-sea cage, it is very necessary to study the deep-sea cage culture environment, and the research results will play a positive role in guiding the production practice of deep-sea cage culture (Naylor R.L.,2000).
