# CFD Simulation of the Safety of Unmanned Ship Berthing under the Influence of Various Factors
## 1 Introduction
[PERSON], [PERSON], and others, based on the Harris wind speed variation power spectrum and a new type of wind pressure coefficient calculation scheme, at the same time, conducted a wind disturbance simulation through the MATLAB platform, and established mathematics that can quantify wind disturbances at any wind speed and direction in the ocean The model can calculate the disturbance resistance and the torque produced by various ocean winds to the ship [28]. [PERSON] simulated the flow field of a ship sailing by solving the RANS equation, studied multiple factors such as the shore distance and the inclination angle of the shore wall effect generated by the ship when the ship sailed along the coast, and determined the shore wall effect in different situations. The torque and the shore suction force provide an operating strategy for ships sailing along the coast [29]. [PERSON] et al. solved the viscous RANS equation to determine the flow field, supplemented by the volume of fluid (VOF) and dynamic grid method for the three aspects of hydrostatic resistance, seakeeping, and maneuverability prediction, and the results showed that the numerical simulation scheme had high accuracy in the prediction of static water resistance of ships at medium and low speeds, but it was not suitable for the prediction of resistance of high-speed navigation. At the same time, a new method was proposed to accurately predict the resistance of high-speed and ultra-high-speed navigation [30]. [PERSON] established two models of static obstacles and dynamic obstacles based on mathematical models of motion; and quantified the risk of ship collision using these two models. At the same time, the external environmental factors, such as quay wall, wind and water flow, and shallow bottom were also considered. For risk quantification, an automatic collision avoidance model was established, allowing, through simulation, and planning of the best navigation route in specific cases, effective suggestions for ship automatic driving [31]. [PERSON] studied the ship's motion response under the combined load of wind, wave,and current, and obtained the overall motion response of the liquified natural gas (LNG) ship terminal when mooring [32]. [PERSON] computed the aerodynamic performances and wind drag acting on the ship hull with and without accommodations, then analyzed the obtained CFD results, the interaction between hull and accommodation on aerodynamic performances, and the wind drag acting on the ship [33]. [PERSON] presented a systematic study comparing results obtained with different computational methods for wave-induced loads and motions of different ship types in regular and random irregular long-crested extremes waves [34]. [PERSON] proposed the unmanned aerial vehicle (UAV) motion system based on digital twin technology needs to have the following functions: (1) the actual UAV movement should drive the virtual platform to build the motion trajectory in real time; Commands on virtual UAV also control the movement of actual UAV in real time. (2) UAV can use visual measurement and other perceptive equipment to obtain environmental information parameters in the course of operation, and can transmit this information to the virtual operating platform in real time. (3) UAV can realize the real-time positioning of the UAV and the control of flight attitude, achieve synchronous positioning, and has intelligent obstacle avoidance function, and can display the drone flight attitude and trajectory on the operating interface [35]. Most of the above-mentioned studies focused are aimed at large traditional transport ships and UAV. There are also some scholars who have conducted research on berth allocation and monitoring system of the terminal system [36; 37; 38; 39]. In recent years, our research team has been working on a virtual test technology for USV based on digital twins, the work can be integrated into berth allocation systems of terminal operating systems.