Numerical Study of Resistance Trimaran Unmanned Surface Vehicle Based on NACA Foil

Unmanned Surface Vehicles (USVs) are used to monitor territorial waters and collect sea data, including hydrographic and oceanographic data. Compared with larger survey vessels, USVs are more flexible and cost-efficient because of their compact form. The latest USV design uses NACA foil as a trimaran hull form with a self-maneuvering system. This design must provide minimal resistance for longer durability during operation. In this study, the authors investigated the relationship between the distance, angle of attack, and shape of the NACA foil as a USV trimaran hull to reduce the resistance. The analysis began with verification and validation based on previous experimental research. Several configurations of the positions of each hull were modelled using an angle of attack of up to 20 °. Computational Fluid Dynamics (CFD) analysis was employed in ANSYS CFX to simulate the model. After obtaining the optimal configuration, variations in the NACA foil on the hull were performed, and the simulation was repeated. The study found that the configuration without an angle of attack, with one hull positioned in front and two hulls positioned behind, using NACA 0024 produces the smallest resistance value. Furthermore, this configuration exhibited wave interference with smaller volume-fraction contours. The study concludes that the angle of attack results in greater resistance owing to the shorter distance between the NACA foils. This research provides insight into the trimaran design of USVs and contributes to the further development of marine robotics technology and unmanned surface vehicles.