Analysis Of Motion And Load Response Of A New Deep-Sea Truss Fish Cage

Most of the fish farms are currently located in sheltered locations,such as fjords and coastal areas,offshore farming tends to be saturated gradually.In order to meet the increasing global demand for seafood and to expand the aquaculture industry,the expansion of fish farms into deeper and farther exposed seas has become a new trend.However,there are few natural barriers in exposed seas,and the sea conditions are complicated.Therefore,deep-sea fish farms are required to have a strong ability to withstand harsh sea conditionsThis paper studied the hydrodynamic characteristics of base module cage structure of a new deep-sea truss-structure Module-based Offshore Fish Farm(MOFF),and proposed a numerical method that can efficiently and accurately predict the motion and load response of the cage in waves and currents.The main contents of this paper are as follows:(1)Studied on a numerical prediction method for the motion and load response of a cage in waves and currents.The truss structure and net were equivalent to concentrated mass points,and the wave force and current resistance of the mass point were calculated by Morison formula;the motion equation of the overall cage was established based on rigid body motion principle,and a calculation program of the motion and load of the cage in waves and currents was written,finally finished the numerical simulation in time domain(2)Studied on the determination method of hydrodynamic coefficients in Morison formula and the optimal analysis of the net grouping scheme.Used CFD method to calculate the horizontal wave forces of the local structure of the cage,then deduced the drag and inertia coefficients of the trusses and spheres under wave conditions and effectively reflected the coupling effect of the truss-sphere combination structure in waves by the value of coefficients.Based on the basic principle of the net grouping method,different net grouping schemes were designed.By considering the calculation efficiency and relative errors,a suitable netting grouping scheme was given(3)Carried out model tests of the motion and load of the cage in waves and currents.Based on the tests results,the validity of the numerical analysis method was verified,and combined with the numerical simulation results,summarized and analyzed the motion and load response of the cage structure in waves and currents.