CFD VALIDATION STUDIES FOR A HIGH-SPEED FOIL-ASSISTED SEMI-PLANING CATAMARAN

This paper details the CFD validation studies carried out as a pre-requisite for multi-fidelity CFD-based design optimization of high-speed passenger-only ferries aimed at reducing far-field wake energy that causes beach erosion. A potential flow code (WARP) and a URANS code (CFDShip) were validated using full-scale measurements of resistance, sinkage, trim, and far-field wake train obtained over a wide range of Fr for two high-speed semi-planing foil-assisted catamarans: Spirit (LOA-22 m) and 1060 (LOA-17 m). This endeavor posed a unique combination of challenges for CFD modeling: the foil appended geometry required complicated surface overset grids, the effect of the water-jet and wind resistance had to be modeled, and a method had to be devised to extrapolate the calculated near-field elevation to get the far-field wake train using Havelock sources. A more concentrated effort was applied to the URANS verification and validation which forms the focus of this paper. The results show that URANS is able to accurately predict the resistance and motions for both vessels when coupled with models that account for the propulsors and air resistance. The overall accuracy of URANS for the performance analysis of the foil-assisted, semi-planing catamarans was adequate to warrant its use as a tool for subsequent design and optimization of a new vessel with significantly reduced wakes.