Numerical Study into the Resistance of a Trimaran Hull at Various Longitudinal Spacing

Abstract

Although the design of trimaran hull has gained popularity at the end of the 20th century, there are few databases available to numerical analysis of trimaran hull. This paper presents a numerical study of the resistance of trimaran hull at various length ratio (S/L) 0.2, 0.3, 0.4 and Froude numbers 0.2 to 0.6 carried out by CFD simulation using FINETM/MARINE by NUMECA software and experimental data. Tri-A has a lower resistance than the trimaran B and C at low Froude number, but at hight Froude number 0.5 and 0.6, the Tri-A has a low resistance than the others. These results are compared with towing tank test data and obtained a lowest difference in the resistance of 0.98 % at TRI-A3. The lowest resistance for the trimaran model is Tri-C5 (Fr=0.6; S/L=0.4) with a total resistance coefficient (CT) of 65.89x10-4, this is due to favorable wave interference with a minimum IF of 0.02. The Interference Factor (IF) follows the same pattern in each configuration, however at maximum Fr, the minimal IF produced on Tri-A3(Fr=0.4; S/L=0.2), Tri-C4 (Fr=0.5; S/L=0.4), and Tri-C5 is 0.22, 0.12, and 0.02, respectively. Where the lowest IF indicates a positive effect because the resistance of the interference hull is lower hull at high speed. The results of this study are expected to be able to strengthen the data base in presenting the effect of interference resistance of the trimaran, which can then be applied directly in determining the magnitude of the ship’s propulsion at the preliminary design stage.