# Characterisation of the Pump-Suction Flow Field of Antarctic Krill and Key Influencing Factors
## 1 Introduction
[17] selected the standard \(k\)-\(\epsilon\) turbulence mode and SIMPLE algorithm to study the flow characteristics of the internal flow field of two electric submersible centrifugal pumps with different vane-guide wheel structures under different working conditions and to investigate the mechanism of the influence of the impeller structure on the external characteristics of the pump, which provides a theoretical basis for the selection and optimisation of the pumps under different working conditions. [PERSON] et al. [18] selected the low-specific-speed centrifugal pump as the object of study. Through a combination of numerical calculations and experimental validation, the impact of gap structure on the performance of centrifugal pumps was investigated. The results demonstrated that utilising smaller gap widths of gap drainage structures can enhance the performance of centrifugal pumps with low specific speeds. However, it was also observed that leakage from the gap would reduce the head of the centrifugal pump. [PERSON] et al. [19] systematically investigated the radial force of the impeller, pressure pulsation, deformation, and vibration of the main shaft under nine distinct flow conditions from the perspective of unstable flow inside the centrifugal pump. They established a correlation between the fluid flow inside the centrifugal pump and the external rotor structure vibration, thereby providing a theoretical foundation for the vibration reduction design and safety monitoring strategy of the centrifugal pump. In the study of solid-liquid two-phase flow in centrifugal pumps, [PERSON] et al. [20; 21; 22] combined theory and engineering practice, applied the computational fluid dynamics-discrete element method (CFD--DEM) algorithm in the mixer, analysed the effects of particle properties on mixing dynamics, and through the test, proved that the method has a certain reliability in the simulation of rotating machinery. [PERSON] et al. [23] tested a multi-stage centrifugal slurry pump and found that the head and efficiency of the pump depended largely on the concentration of the solid phase in the slurry. [PERSON] et al. [24] used CFD--DEM coupled simulation to calculate the unsteady solid-liquid two-phase flow in a centrifugal pump and obtained the trajectory and solid-phase volume rate of the 1.0-3.0 mm particle group in the centrifugal pump. [PERSON] et al. [25] took the dredging pump as an object of study, combined CFD with experiments, and carried out a more in-depth study of the solid-liquid two-phase flow, and the results proved that modelling the solid-liquid two-phase flow using Eulerian-Eulerian methods can analyse the performance level of existing dredging pumps or predict the losses of new dredging pump designs. With the transformation of the global fishery resources development mode in the direction of intensification and intelligence, the rapid development of new facilities and equipment, such as deep-sea aquaculture platforms [26; 27; 28; 29], has prompted the live fish catching link to become a key node of the modern fishery industry chain. In this context, centrifugal pump technology designed based on the principle of fluid dynamics is gradually widely used in fish suction pumps after engineering improvement [30]. In comparison with conventional manual fishing methods, the utilisation of a suction pump offers several advantages. The labour intensity of the former is notably higher, with a daily operation capacity of a single vessel limited to 3 tons. Furthermore, the catch damage rate is observed to be between 15 and 20 per cent, and the operating efficiency is low, with a handling capacity of less than 2 tons per hour. In contrast, the suction pump has the capacity to increase the efficiency of live fish delivery to 10-15 tons per hour. Additionally, it can control the mechanical damage rate at less than 3 per cent, thereby greatly improving the level of mechanisation. This is achieved by effectively reducing the labour intensity and enhancing the quality of fish and fishing efficiency.