![]() To solve this problem, computational fluid dynamics (CFD) was employed to investigate the dynamic temperature and velocity fields in the juvenile fish rearing tank. To maintain the water temperature and velocity distributions in the optimal growth conditions for fish, particularly juvenile fish, is a great challenge. These qualitative conclusions may serve as a reference for gas-liquid transport simulations under rolling conditions.īoth velocity and temperature field performance of fish octagonal rearing tank played an important role in the recirculating aquaculture system (RAS). In addition, as the initial gas volume fraction increased, the effects of rolling motion on the transient flow behaviors decreased gradually. Compared with the rolling angle, the transient flow behaviors are more sensitive to the rolling period. The variation of additional inertial force and pressure drop increased with the increase of rolling angle and the decrease of the rolling period. The results showed that the rolling motion caused agglomeration of dispersed bubbles and gas slugs into a continuous gas column, increased the cross-sectional void fraction significantly. Then, the variation in transient flow behaviors by horizontal pipe (L = 2.0 m, D = 0.035 m) with varying rolling conditions (θm = 2°-6°, T = 0.5–4.0 s) and flow velocities (jG = 0.1–10.0 m/s, jL = 0.1–0.5 m/s) are investigated. First, the simulation results are compared with the experimental data, which revealed a reasonable agreement. The three-dimensional rolling flow fields are simulated using the volume of fluid (VOF) model, RNG k−ε turbulence model and additional inertia force method. ![]() In this paper, the gas-liquid two-phase flow numerical model of rolling horizontal pipe is established based on CFD code combined with user-defined functions (UDF). The investigation of transient flow behaviors of gas-liquid two-phase flow under ocean conditions is vital to the application of gas-liquid transport in ocean engineering area. Based on the FFGR, the flow field of aquaculture vessel in rolling oscillations are evaluated for six fish species, including Atlantic salmon and Pseudosciaena crocea. ![]() Statistical analysis on the water velocity indicates that the period-averaged FFGR increases with velocity. The wavelet and fast Fourier transformation on the mass averaged mean kinetic energy reveals a steady-state of the rolling flow condition after 100 oscillating periods. A typical rolling condition of an aquaculture tank from the analyses of response amplitude operator (RAO) was used for the flow field analysis. The fish fitting guaranteed rate (FFGR) based on the statistical cumulative distribution probability is presented and used to analyze water flow. In this paper, the flow field characteristics in an aquaculture tank was numerically investigated. The flow field in fish rearing tanks aboard the vessel is a prerequisite for fish welfare. The mobile aquaculture vessel is expected to be a sustainable way for future nutritious food due to its mobility, potential production rates and environment preservation. The water inlet slightly affects the volume of this low-velocity zone. For all simulations, there is a low-velocity region along the rolling axis in the middle of the fishing tank. The residence time of water in the tank seems insensitive to both rolling angle and period. Moreover, if the rolling period exceeds a threshold, such as 10s in this paper, the velocity increment is tiny. For cases with different rolling angles, the magnitude of water velocity in the tank is very sensitive to the rolling angle and increases with it for cases with different rolling periods, velocity magnitude decreases as rolling periods increase. Roll accelerates the velocity magnitude of water in the tank and shortens the circulation time. Through our simulations, we find that water inlet and drainage play a limited role in accelerating water velocity magnitude when being compared with the effect of the roll. In this paper, the flow characteristics (residence time, velocity uniformity) in a force-rolling aquaculture tank are numerically investigated and analyzed by statistical methods. The fishing platform is expected to be a sustainable method for offshore aquaculture, which can avoid fish escapes by using tanks in harsher sea state and meanwhile make use of natural water.
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