Experimental and Numerical Studies on Resistance of a Catamaran ‎Vessel with Non-Parallel Demihulls

Abstract

In common catamaran vessels, demihulls are parallel to each other. In this paper, the total resistance of a catamaran vessel with non-parallel demihulls is investigated experimentally and numerically. Experiments are carried out at different Separation Ratios (S.R.) that is the ratio of fore to aft separation of the catamaran demihulls; and also in two ratios of Length to Separation in amidships (L/Sm). FLUENT solver based on finite volume method (FVM) was used for numerical solution. Applying VOF model, free surface around catamaran vessel and total resistance is calculated and compared with experimental results. Finally, frictional resistance of catamaran from ITTC 1957 correlation line is calculated and compared with CFD frictional resistance. The results show that, non-parallel demihulls cause the total resistance to increase at Froude numbers below 0.8 and decrease resistance at Froude Numbers over 0.8. In the numerical part, at low Froude numbers, numerical results have an error up to 10% relative to model test results, but error increases at high Froude numbers up to 25%.