Resistance Predictions for a High-Speed Sealift Trimaran

The purpose of this work is to compare the capability of two different numerical techniques for predicting the calm-water resistance of a high-speed sealift trimaran. The vessel is representative of a future advanced naval design that must be able to travel long distances with heavy payloads, but is constrained geometrically in order to operate in austere ports upon arrival. It has a relatively shallow draft and has an extendable center hull that possesses a wave-piercing bow. This particular design has hulls that are of essentially equal dimensions. For comparison of the codes, a series of large-scale model tests was conducted for six different configurations of the three hulls (variations of overall vessel beam and length). A thin-ship theory is shown to be effective in predicting resistance. Results for both the absolute value and the relative change in resistance due to change in the hull configuration, together with the computational efficacy of the method demonstrate utility for the designer. The complex effect on the resistance due to the proximity of the three hulls is addressed in a first-principle manner to enhance the prediction from the thin-ship theory. The commercial computational fluid dynamics code FLUENT is shown to more accurately predict the resistance when the calculations are performed with the body fixed at the experimental sinkage and trim. The temporal expense associated with computational fluid dynamics is reduced in this study by using very simple computational grids. Also, the solution convergence is enhanced by using polyhedral finite volumes which improve cell skewness.

Presented at the International Conference on Numerical Ship Hydrodynamics (9th) held in Ann Arbor, Michigan, on August 5-8, 2007. Published in the proceedings of the conference (unnumbered pages), 2007. Prepared in cooperation with University of New South Wales (UNSW), and with Seoul National University. Prepared in collaboration with Naval Surface Warfare Center. The original document contains color images. This article is from ADA495720 International Conference on Numerical Ship Hydrodynamics (9th) held in Ann Arbor, Michigan, on August 5-8, 2007