Numerical investigation of the components of calm-water resistance of a surface-effect ship

The elements of the calm-water resistance of an surface-effect ship are studied with two different numerical methods. A potential-flow-based method that satisfies linearized free-surface boundary conditions is used to predict the wave resistance of the sidehulls and air cushion. A RANS-based program that employs a single-phase level set method is used to simulate the flow around an SES of a nonlinear viscous fluid. Detailed comparison of the dynamic wetted surface, the free-surface elevation, and the wave, cushion, and frictional drag is made for a geometry that has experimental resistance data. It is shown that the linear free-surface boundary conditions of an inviscid fluid are accurate for prediction of wave drag. Disagreement is present between the two methods for the free-surface elevation behind the vessel, which might possibly be due to the transom-stern model that is used in the potential-flow method. The small difference between the numerically predicted resistance and the experimental measurement is attributed to the error in the seal and air drag models that are used in this study.