Numerical investigation of a stepped planing hull in calm water

Stepped planing hulls enable the feasibility of running at relatively low Drag-Lift ratio by means of achieving more optimal trim angle at high speeds. Currently, there is no precise method to analyze these hulls over the full range of operating speeds. In this study, a three-dimensional computational fluid dynamics (CFD) model using volume of fluid (VOF) approach is presented for examining the characteristics of a planing hull having one transverse step. A procedure is presented to transform a series of fixed-position simulations into a free to heave and pitch simulation. Resistance, lift, running draft, dynamic trim angle, and wetted area are compared with available experimental data and those of a semi-empirical method at volumetric Froude number in the range of 2.41-7.12. Centerline wake profile and reattachment location are compared with those of empirical equations. Wetted area at forebody chines-dry mode is qualitatively compared with a typical under water photograph of a stepped hull. The quantitative and qualitative results are found in acceptable correlation with experimental data, hence they can be reliably used in the stepped hull hydrodynamic investigation.