CFD Analysis of a Stern Flap Effect on the Hydrodynamics of a Catamaran Ship

Abstract

Maritime transport is under increasing pressure to improve hydrodynamic efficiency and decrease emissions. catamarans offer operational benefits; however, they are limited by wave-making resistance at high speeds. Stern flaps are effective for monohulls, but their optimization for catamarans is inadequately investigated owing to the complexities of twin-hull hydrodynamics. this work utilizes computational fluid dynamics simulations to comprehensively assess stern flap performance on a catamaran under varying ship speed conditions and angles of attack. the findings indicate that a 0° flap decreases overall resistance by an average of 5.5%, despite a 1.76% increase in wetted surface area, accomplished by separation-free flow and balanced trim correction, which includes a 42% reduction in stern-squat at higher Froude numbers. conversely, a 20° flap elevates resistance by up to 8.8% at high froude numbers due to flow separation, which exacerbates a 4.48% increase in wetted area and a 0.49% rise in heave, despite its 93% geometric trim correction. research results indicate that neutral flap angles improve catamaran efficiency by avoiding three hydrodynamic drawbacks of higher angles: increased pressure drag, expanded wetted surface, and reduced stability. High-angle configurations are not recommended for any operating profiles.