A hybrid RANS-LES approach is used to resolve the Fore-body Side Vortex (FSV) separating from the KVLCC2 hull at 30° drift angle and Reynolds number ReLoa ≈ 2.56e6. The performance of the DES approach is evaluat...A hybrid RANS-LES approach is used to resolve the Fore-body Side Vortex (FSV) separating from the KVLCC2 hull at 30° drift angle and Reynolds number ReLoa ≈ 2.56e6. The performance of the DES approach is evaluated using a proper grid study. Besides, the following aspects of the CFD results are investigated: the resolution of turbulent energy, the prediction of instantaneous and time-averaged vortical structures, local flow features, the limiting streamlines and the evolution of the vortex core flow. New PIV data from wind tunnel experiments is compared to the latter. The results form a basis for future investigations in particular on the vortex interaction further downstream and the applicability of different kinds of turbulence models to trailing vortices like the FSV. Turbulence modelling is realised with the k-ω-SST-IDDES model presented in [1], the grids’ cell count is 6.4 M, 10.5 M and 17.5 M. Grid convergence of the time-averaged vortex core flow is observed. OpenFOAM version 1806 is used to carry out the simulations and snappyHexMesh to build the mesh.展开更多
The added resistance of KVLCC2 in short and regular head waves has been studied theoretically and experimentally. Model tests are performed to determine how well the asymptotic formula （Faltinsen et al. 1980） predic...The added resistance of KVLCC2 in short and regular head waves has been studied theoretically and experimentally. Model tests are performed to determine how well the asymptotic formula （Faltinsen et al. 1980） predicts the typical level of added resistance in short waves. Because the asymptotic formula neglects the effects of ship motions, it is combined with theoretical methods to calculate the added resistance in long waves using an function to predict the added resistance in the intermediate wavelength region where both ship motions and wave reflection are important. A unique feature of this experiment is that the ship model is divided into three segments to explore the added resistance distribution with respect to hull segment. This paper discusses the sensitivity of experimental results to the quality of the incident regular head waves. Moreover, a novel procedure for analyzing added resistance is described. Finally, the experimentally determined added resistance of KVLCC2 is compared with theoretical results. It is shown that the added resistance from the combined theoretical methods agrees well with experimental results in both the intermediate and short wave regions. The use of hull segments shows that added resistance is concentrated primarily at the bow.展开更多
This paper presents numerical predictions of ship manoeuvring motions with the help of computational fluid dynamics （CFD） techniques. A program applying the modular concept proposed by the Japanese ship manoeuvring ...This paper presents numerical predictions of ship manoeuvring motions with the help of computational fluid dynamics （CFD） techniques. A program applying the modular concept proposed by the Japanese ship manoeuvring mathematical modelling group （MMG） to simulate the standard manoeuvring motions of ships has been initially developed for 3 degrees of freedom manoeu- vring motions in deep water with regression formulae to derive the hydrodynamic derivatives of the vessels. For higher accuracy, several CFD generated derivatives had been substituted to replace the empirical ones. This allows for the prediction of the maneuve- rability of a vessel in a variety of scenarios such as shallow water with expected good results in practice, which may be significantly more time-consuming if performed using a fully CFD approach. The MOERI KVLCC2 tanker vessel was selected as the sample ship for prediction. Model scale aligned and oblique resistance and Planar Motion Mechanism （PMM） simulations were carried out using the commercial CFD software StarCCM＋. The PMM simulations included pure sway and pure yaw to obtain the linear manoeuvring derivatives required by the computational model of the program. Simulations of the standard free running manoeuvers were carried out on the vessel in deep water and compared with published results available for validation. Finally, simulations in shallow water were also presented based on the CFD results from existing publications and compared with model test results. The challenges of using a coupled CFD approach in this manner are outlined and discussed.展开更多
文摘A hybrid RANS-LES approach is used to resolve the Fore-body Side Vortex (FSV) separating from the KVLCC2 hull at 30° drift angle and Reynolds number ReLoa ≈ 2.56e6. The performance of the DES approach is evaluated using a proper grid study. Besides, the following aspects of the CFD results are investigated: the resolution of turbulent energy, the prediction of instantaneous and time-averaged vortical structures, local flow features, the limiting streamlines and the evolution of the vortex core flow. New PIV data from wind tunnel experiments is compared to the latter. The results form a basis for future investigations in particular on the vortex interaction further downstream and the applicability of different kinds of turbulence models to trailing vortices like the FSV. Turbulence modelling is realised with the k-ω-SST-IDDES model presented in [1], the grids’ cell count is 6.4 M, 10.5 M and 17.5 M. Grid convergence of the time-averaged vortex core flow is observed. OpenFOAM version 1806 is used to carry out the simulations and snappyHexMesh to build the mesh.
基金part of the research project SeaPro, which is sponsored by Rolls-Royce Marine and the Research Council of Norway
文摘The added resistance of KVLCC2 in short and regular head waves has been studied theoretically and experimentally. Model tests are performed to determine how well the asymptotic formula （Faltinsen et al. 1980） predicts the typical level of added resistance in short waves. Because the asymptotic formula neglects the effects of ship motions, it is combined with theoretical methods to calculate the added resistance in long waves using an function to predict the added resistance in the intermediate wavelength region where both ship motions and wave reflection are important. A unique feature of this experiment is that the ship model is divided into three segments to explore the added resistance distribution with respect to hull segment. This paper discusses the sensitivity of experimental results to the quality of the incident regular head waves. Moreover, a novel procedure for analyzing added resistance is described. Finally, the experimentally determined added resistance of KVLCC2 is compared with theoretical results. It is shown that the added resistance from the combined theoretical methods agrees well with experimental results in both the intermediate and short wave regions. The use of hull segments shows that added resistance is concentrated primarily at the bow.
基金Funded FP7 Framework Project SHOPERA (Energy Efficient Safe Ship Operation) (Grant No. 605221 under the theme SST.2013.4-1)Results were obtained using the EPSRC funded ARCHIE-West High Performance Computer (www.archie-west.ac.uk).EPSRC (Grant No. EP/K000586/1)
文摘This paper presents numerical predictions of ship manoeuvring motions with the help of computational fluid dynamics （CFD） techniques. A program applying the modular concept proposed by the Japanese ship manoeuvring mathematical modelling group （MMG） to simulate the standard manoeuvring motions of ships has been initially developed for 3 degrees of freedom manoeu- vring motions in deep water with regression formulae to derive the hydrodynamic derivatives of the vessels. For higher accuracy, several CFD generated derivatives had been substituted to replace the empirical ones. This allows for the prediction of the maneuve- rability of a vessel in a variety of scenarios such as shallow water with expected good results in practice, which may be significantly more time-consuming if performed using a fully CFD approach. The MOERI KVLCC2 tanker vessel was selected as the sample ship for prediction. Model scale aligned and oblique resistance and Planar Motion Mechanism （PMM） simulations were carried out using the commercial CFD software StarCCM＋. The PMM simulations included pure sway and pure yaw to obtain the linear manoeuvring derivatives required by the computational model of the program. Simulations of the standard free running manoeuvers were carried out on the vessel in deep water and compared with published results available for validation. Finally, simulations in shallow water were also presented based on the CFD results from existing publications and compared with model test results. The challenges of using a coupled CFD approach in this manner are outlined and discussed.
