Abstract Traditional methods, both experiment al and numerical approaches, for the study of ship resistance mainly focus on the model-scale. However, the differences between the full-scale prediction (extrapolated from the results of the model) and reality, caused by the scale effect, make it difficult for the model-scale research to meet the engineering requirements. In this study, the URANS (unsteady Reynolds-averaged Navier–Stokes) simulations of ship resistance in calm water are carried out to predict the resistance components and the resistance of the appendages of the full-/model-scale fully appended ship with 2DOF (two degrees of freedom), and the scale effect on the resistance of the appendages is investigated. The fully appended surface combatants DTMB5415 with the scale ratio 1:46.6 and 1:1, which is free to heave and pitch, are selected as the computational models. The ship velocities corresponding to Fr=0.15–0.3 are taken into account according to the model-scale benchmark cases provided by Laboratory of Ship Model Towing Tank of Naval Architecture & Ocean Engineering College of Huazhong University of Science and Technology. All the simulations are solved using an in-house CFD code (computational fluid dynamics) and a dynamic overset grid approach in this study. The multi-layer wall function model is used for the full-scale simulations. First of all, the model-scale simulations in calm water are conducted and the results are compared with the experimental data to verify the reliability of the numerical method. The simulation results show a good agreement with the EFD data (experimental fluid dynamics) and the differences of total resistance are less than 5%. Then the full-scale simulations are performed and the scale effect on the resistance components is discussed. Moreover, the resistance of each appendage is monitored separately and the full-/model-scale resistances of all the appendages are compared in detail to study the scale effect on appendages.
Li et al. (Sun,) studied this question.