Resistance Prediction & Running Attitude of High-Speed Semi-Planing Hull Using Computational Fluid Dynamics

Abstract

Precise resistance estimations and running attitude are crucial factors in the design and production phase of hulls. Model research has conventionally relied on experimental model testing, but this methodology is both costly and time consuming. A precise estimation of ship's hull resistance yields the accurate required propulsive power leading to significant cost saving. To estimate the resistance in the design process, Computational Fluid Dynamics (CFD) methods are extensively implemented. Though, even with the maturity of modern day CFD tools, experimental measurements are still the most reliable solution for resistance measurement. However, as said earlier, due involvement of cost effects, CFD can be seen as near accurate replica of experimental facility, provided the results are well validated. CFD simulations for semi-planing hull is an extremely challenging process. However, an effort has been made to address the issues in simple manner. The simulations are carried out to predict resistance in both displacement and planing modes. Numerical Computation is done by solving RANS equations. Multi-phase Volume of Fluid (VOF) method is used for capturing the free surface. For turbulence and kelvin wake pattern K-e & SST K-ω models are used. Resistance of a semi-Planing hull is also predicted using empirical methods. A comparative analysis between the results from empirical methods, experimental results and CFD results is undertaken to get a validated estimation technique for resistance of Semi-planing hull. CFD simulations has been carried out using ANSYS Fluent software on Semi-displacement R/V Athena hull (DTMB 5365). The CFD results are in good agreement with experimental and empirical results. Once resistance prediction technique for CFD was finalized, the simulations were carried out on a Test hull to predict its resistance and running attitude. Recommendations are made to optimize the test hull design by adding lifting rails and spray rails on several positions of hull geometry.