Hydrodynamic analysis of a SWATH planing USV based on CFD

Abstract

As small waterplane area twin hull (SWATH) has excellent seakeeping performance and low wave resistance, this structure has been applied to unmanned surface vehicle (USV). However, with the increase of speed, fluid resistances will increase exponentially because of its large wet surface. A way to improve this situation is to reduce the depth of draft at high speed, so that all or a part of the volume of the submerged bodies is above the surface of water. Based on this idea, a new type of SWATH USV is designed in this paper. The two submerged bodies of the USV have a planing boat shape. At high speed, hydrodynamic lift force generated by the submerged bodies of the USV can push most part of the submerged bodies out of water, which can greatly reduce the resistance of the USV. In this paper, computational fluid dynamic (CFD) method is used to analyze the attitude and resistance of the USV at different speed, showing that the designed USV can achieve the expected movement characteristics and low resistance at high speed.