CFD Study on Hydrodynamic Performances of a Planing Hull

Abstract

The scope of the present study is to investigate the effects of various geometrical hull features, such as tunnels, spray rails and whiskers on the hydrodynamic performance of a high-speed planing hull. The criteria being tested to emphasize the boat performance are the total drag, sinkage and trim angle. In addition, the decomposition of the resistance into viscous and wave-making resistance are taken into consideration. The study starts with a validation test against experimental data in order to accentuate the capability of the Computational Fluid Dynamics CFD simulation to accurately predict the total drag and trim angle of the initial form. This is later followed by a verification study based on the Richardson Extrapolation method with a grid- and time-step-convergence test in order to predict the numerical errors during the simulation. After establishing the simulation parameters regarding the proper grid size and time step, the comparative study takes place for five hull shapes and two whisker configurations while the boat is sailing at eight different speeds. The assessment of the hydrodynamic flow parameters is evaluated compared to the initial form in order to investigate the influence of the geometry change on the hydrodynamic performances of the boat. Validation of the numerical results showed the reliability of the CFD simulation to accurately predict the drag and trim angle of the boat, while the comparative study revealed that the total drag can be reduced by up to 9%, especially at higher speeds.

Numerical Investigation of Single and Double Steps in Planing Hulls

“…The results noticed from the different grid sizes agreed well with the experimental results. A total of four mesh refinement sizes were used and the resistance percentage error between the EFD and CFD was within the recommended range [34,35] and the asymptotic trend is detected for the latest mesh sizes (M3 and M4), as shown in Figure 6 The ITTC guidelines [33] recommend a uniform refinement ratio in the range of √ 2 and 2. In the mesh independence study, four different sizes were used to achieve mesh independence.…”