A Comprehensive Investigation Of Ship Resistance Prediction Based On CFD Theory

Computational Fluid Dynamics (CFD) is applied widely in ship design for it can improve the capacity and efficiency of ship design. It is a hot research topic and more and more researchers focus on it and are studying on it in various academic, engineering and technology opinions. The viscous flow around ship is a complex 3-D phenomena which includes complex viscous flow near ship wall, free surface, ship body motions and so on. Thus numerical simulation of flow around ship which takes the external influence factors into consideration is a task of great challenge and importance. With the rapid development of computational methods and computer technology, now the comprehensive investigation of ship resistance prediction based on the CFD tools is possible.Recent developing and research progress of the ship resistance calculation is systematically reviewed here. The numerical towing tank applied to simulate the water flow around ship is established based on the secondary development of commercial CFD software. The capacity of resistance prediction for model ship voyaging in the numerical towing tank is verified by a physical test of fishery administration ship, the reasonable calculation results are obtained which agree well with the measured ones in physical model experiment. The different transition of laminar flow turning to turbulent flow due to model various scales and the ship hull roughness influence on resistance are discussed in the present paper. In order to solve the problem that the model and full ship are in different scale, boundary layer trip are set up around the model bow in physical model experiment, it is proved here that it is not necessary to do it while CFD simulation method is hired.A new method to predict full-scale ship resistance based on CFD approach is outlined here. The ship form factor is obtained by double-model theory in turbulent flow model, and the wave resistance is calculated by ideal fluid flow and multi-phase theory. Whatever the theory of turbulent flow or ideal fluid flow is used to simulate flow around ship, lesser calculation time is consumed. The simulation can easily be carried out on Personal Computer and it keeps good accuracy. Theoritical calculation and resistance prediction for Ship S60 and KCS are done as well as the comparison with experiment results. It shows the new method fits for engineering application.Since trim and sinkage are significant while vessels advancing forward with high speed, the predicted vessel resistance based on restrained model theory or experiment may not reflect resistance of vessels during voyage. It is necessary to take hull gesture influence into account for resistance prediction of high speed ship. Here the resistance problem of high speed ship is treated by the viscous flow theory regime, the dynamic mesh technique is adopted to coincide with variation of hull gesture of high speed vessel on voyage. The simulation of the models of S60 ship moving in towing tank with high speed are conducted by using the above theory and technique. The calculation results both of the resistance and hull gesture are in good agreement with the experimental data. It indicates the resistance prediction for high speed vessels should take hull gesture into consideration and the dynamic mesh method proposed here is useful to investigate the resistance calculation for high speed vessels.The trimaran ship is a new type ship with unique hydrodynamic characteristic. Some research methods of hydrodynamics for single-hull ship can not be applied to the trimaran ship. Here a numerical towing test of trimaran model is conducted with the aids of dynamic mesh techniques. The rapidity and influence of hull gesture is investigated and resistance of trimaran is forecasted. Compared with experimental data, it is proved that the comprehensive method of resistance prediction promoted here is reliable, and it will be a useful tool at the ship design stage.