Numerical evaluation (CFD) of Wake and Thrust deduction fraction of a Warped Hard Chine Hulls Systematic Series

This work is strictly related with the paper " The Naples Warped Hard Chine Hulls Systematic Series ??? First Part: Resistance in Still Water" presented at this same Symposium. The aim of this work is to show the results of the numerical evaluation of the hull-propeller interactions obtained by the commercial RANSE Computational Fluid Dynamic software CD-ADAPCO Star CCM+. In literature there is a significant lack of experimental data on wake and thrust fraction magnitude especially regarding medium and high speed vessels. This is due to the high costs and to the reduced reliability of the tests carried out with small models whose dimensions are constrained by the high Froude numbers. In spite of the high model speed, the smallness of the models induces small Reynolds numbers and therefore not negligible scale effects on propellers dynamic (laminar flow) and on wake intensity. In this paper a numerical analysis has been performed on the parent hull of the series. In particular, three procedures, characterized by simulations with different degree of freedom and different relations with experimental data, have been applied. The simulations have been carried out in the speed range Fr = 0.5 ÷ 1.5. This way is submitted also as an alternative to towing tank experiments on big models if these tests are not feasible.