To achieve efficient and sustainable marine aquaculture, STAR-CCM+ was used to simulate the internal and external field characteristics of a semi-submersible aquaculture platform based on a porous media model, focusing on the influence of incoming flow velocity and net solidity ratio. The results indicate that the flow field distribution around the platform exhibits no significant regularity and that low-velocity vortex regions are primarily concentrated near the pillars and nets. After velocity attenuation, the velocity reduction coefficients at the centers of the three cages are 90.26%, 63.65%, and 52.56%, respectively. Furthermore, the velocity attenuation inside the cages is minimally influenced by incoming flow velocity, with a maximum difference of 3.10%. In contrast, differences in net solidity ratio significantly affect velocity attenuation, particularly in downstream regions. The velocity reduction coefficient in the third cage varies by up to 43.25% depending on the net solidity ratio. These findings provide practical insights for the engineering design and application of aquaculture platforms.

Fish schooling is a common phenomenon in nature, and offers valuable inspiration for the design of underwater biomimetic propulsors. To investigate the fluid interaction mechanisms among individuals in an oblique tandem arrangement, this study conducts two-dimensional numerical simulations of three airfoil-based biomimetic fish models. Using Computational Fluid Dynamics, the effects of streamwise spacing ($L_x=0.8$–$1.2$) and orientation angle ($\theta =10$–$30°$) on the hydrodynamic performance and wake characteristics of each fish are examined for a selected set of five representative cases. The results show that, within the present parameter range, the overall time-averaged thrust coefficient of the three-fish school in an oblique tandem arrangement is higher than that of a single fish, with an increase ranging from 16% to 22%. As the streamwise spacing increases, the mutual interference among individuals weakens, and the overall thrust gain gradually decreases. With increasing orientation angle, the thrust gain of the leading and middle fish decreases, whereas that of the trailing fish transitions from negative to positive. At a small orientation angle ($\theta =10°$), the leading and middle fish show a substantial thrust increase. This preliminary study indicates that, within the examined parameter space, appropriately adjusting the streamwise spacing and orientation angle can effectively enhance the overall thrust of a fish school in an oblique tandem arrangement and enable the trailing fish to achieve a thrust gain.

This study establishes a triangular numerical wave tank based on the viscous incompressible Navier–Stokes equations. The model is implemented in STAR-CCM+, employing the Reynolds-Averaged Navier–Stokes equations and the Volume of Fluid method, combined with velocity boundary wave-making and momentum source wave-making techniques for wave generation. On this basis, systematic numerical simulations of oblique and head-on waves were conducted, along with simulation studies of wave interactions with both fixed and floating circular cylinders. The accuracy and reliability of the model were validated by comparing simulation results with theoretical solutions and existing literature data. The results demonstrate that the performance of this triangular wave tank is not affected by the wave incident direction. It can stably generate high-quality oblique and head-on waves, making it suitable for numerical simulation studies of wave–structure interactions.