Towards CFD guidelines for planing hull simulations based on the naples systematic series

Abstract

Due to their higher motion amplitudes and instabilities, numerical simulations of planing hulls using Computational Fluid Dynamics (CFD) codes are more difficult than that of displacement ships. Indeed, for an accurate evaluation of the hydrodynamic performances of planing craft, the high-fidelity estimation of the pressure field around the hull is crucial. For this reason, validations and comparisons with experimental data are still important to identify the guidelines for both simulation settings and mesh generation. In this paper, two commercial packages will be compared focusing on a resistance case for the parent hull model (C1 hull) from the Naples Systematic Series (NSS) at four Froude numbers (Fr).

The NSS is a new systematic series of hard chine hulls intensively tested in planing and semiplaning speed range, De Luca et al. [1]. It has been chosen for the hull form: it is characterized by a warped bottom and a sectional area curve significantly different from the prismatic hulls. These differences amplify the difficulties in finding out the exact pressure distribution on the bottom and, consequently, make the evaluation more stringent.

The Unsteady Reynolds-Averaged Navier-Stokes flow solvers results are validated using these benchmark experimental data. Also, grid independence, iteration, and time-step convergence analysis for response variables (resistance coefficients, wetted surfaces, and dynamic trim angles) follow the recommendations published in the verification and validation (V&V) study from De Luca et al. [2]. Hence, the two software are more compared on different features such as the mesh deformation, the overset method, and the correction of numerical ventilation classically observed below the hull. The results show that both software can provide consistent values and that new guidelines are now

identified to improve the reliability of the simulations.