Application of a VOF Multiphase Flow Model for Issues concerning Floating Raft Aquaculture

Abstract

Floating raft aquaculture has gradually become a mainstream aquaculture model in the waters of Changhai County, Dalian. To quantitatively describe the impact of floating raft aquaculture facilities on the hydrodynamic environment of nearby sea areas, in this study, we took a single floating raft aquaculture structure as the research object and built a numerical prediction model for water flows passing through the floating raft aquaculture structure using a six-degree-of-freedom VOF (volume of fluid) multiphase flow simulation method based on an overset moving mesh system. Then, we verified the numerical model by utilizing oblique hydraulic jumps and water flows passing through a submerged bar. As shown by the findings, the simulated values are in good agreement with the theoretical solutions and measured values, indicating that the model features high precision and great stability. The impact of the raft area on the hydrodynamic force was introduced into the source term of an equation for consideration. In order to further determine the hindering effect of the raft body on the water body, transport equations and the tracer method were used to simulate the impact of floating raft aquaculture facilities on the water exchange performance of nearby sea areas. This study shows that the VOF multiphase flow model can be easily and accurately applied to studies on floating raft aquaculture, which can greatly reduce the limitations of experiments that utilize pure hydraulic models, wherein the impacts of floating raft aquaculture facilities on hydrodynamic force are generally considered simply based on observations, water roughness or the secondary drag force coefficient, thereby effectively improving the scientific understanding of the physical mechanism involved in floating raft aquaculture.