A numerical investigation of sinkage and trim effects on the resistance of trimaran hull form in calm water

Abstract

Objectives The motion attitude (sinkage and trim) of a semi-planing ship (at Froude numberFr > 0.4) have significant effects on its resistance performance during voyage. The sinkage and trim effects on the resistance components (frictional resistance and pressure resistance) is discussed.Methods A CFD study is carried out on the resistance performance of trimaran in calm water, and the k-ε turbulent model and overlapping grid are adopted. The free model and constrained model are computed. The computed results are compared to analyze the effects of sinkage and trim on the resistance components.Results The results show that the change of total resistance caused by sinkage and trim is more than 20% in semi-planing conditions. The sinkage and trim have a significant effect on the pressure resistance, up to nearly 50%; and a relatively small effect on frictional resistance, less than 8.5%. More than 90% of the resistance increase caused by motion attitude comes from the change of pressure resistance.Conclusions Predicting the motion attitudes and resulting pressure resistance changes accurately is extremely important for semi-planing trimaran.

Keywords

• semi-planning
• trimaran
• resistance
• sinkage and trim