Study of a Container Ship with Breaking Waves at High Froude Number Using URANS and DDES Methods (original) (raw)
Related papers
Numerical Simulation of Ship Bow Wave Breaking using SST-DES and SST-URANS
2018
The phenomena of wave breaking, known as white water, always occurs when ships advances in high speeds. The common issue has attracted many researchers since its complex mechanism and effects on the performance of ship. Since the shortages of towing experiments, such as expensive cost, insufficient information in flow field, et al. Computational fluid dynamics (CFD) is becoming gradually a popular approach to study the overturning and breaking of ship bow wave. The advantage to provide detailed information in flow field is very helpful to understand better the mechanism of breaking wave. The CFD solver naoe-FOAM-SJTU, which is developed on the open source software OpenFOAM, is used to investigate the wave breaking phenomena of the bow wave of KRISO Container Ship (KCS) model with sinkage and trim. In the present work, the SST-DES and SST-URANS turbulence model are adopted to simulate the bow wave breaking of KCS in different advance speeds, i.e. Fr=0.26, 0.30, 0.35. In the simulatio...
Breaking wave at the bow of a fast displacement ship model
Journal of Marine Science and Technology, 2003
We investigated the flow structures under the bow wave generated by a fast displacement ship model (INSEAN model 2340) in the presence of wave breaking. The data acquired were also used for a detailed database for CFD validation. The mean and r.m.s. point-wise values of the wave height were measured by means of a finger probe. The intensity of the breaking wave was taken as the r.m.s value of the wave height. The mean velocity field under the free surface was measured at 0.15 L PP and 0.2 L PP downstream of the fore perpendicular by means of a 5-hole Pitot probe. Uncertainty assessment of the wave height and velocity field results was performed following the AIAA Standards S-071-1995. Preliminary CFD results from a RANSE code with a breaking model are shown in comparison with the measured data.
Numerical modeling of breaking waves generated by a ship?s hull
Journal of Marine Science and Technology, 2004
functions, the traditional boundary-fitted grid is not suitable and other approaches have been devised to overcome the problem. We note the marker-and-cell method, initially proposed by Harlow and Welch, 3 and with further developments by Chen et al., 4,5 the volumeof-fluid method by Hirt and Nichols 6 (see also the review by Scardovelli and Zaleski, 7 and the level-set method, 8,9 which has recently been used for the simulation of a three-dimensional viscous flow featuring the plunging of the bow breaker with subsequent air-entrapment and the formation of a second jet. 10 Despite their limitations, when they are applicable surface-fitting approaches deliver excellent results, as is evident from the workshop held in Gothenburg, 11 and many researchers worldwide use this type of algorithm.
Preliminary study about the wave influence on the ship hydrodynamics
Marine Systems & Ocean Technology
The computational modeling is an important tool that can be used to assist the development of engineering projects. In this work a two-dimensional numerical model, under development at the Universidade Federal do Rio Grande, is used to describe the ship hydrodynamics (using three degrees of freedom) and understand the behavior under variation of: thrust produced by the engine and effects of external forces, focusing in wave influence. This work is based on the development of the numerical model to investigate the ship hydrodynamics using three degrees of freedom through the Lagrangian Mechanics. The thrust is represented in exponential form increasing or decreasing over 30 hours of numerical simulation, on the other hand, the wave properties are obtained from a numerical model SWAN for the coastal region adjacent to the Patos Lagoon. The vessel velocity is a function of the thrust and for both simulations some variations are observed for the two components during the first hour of simulation. During this period of simulation, the variation of the initial velocity favors the more effective action of inertial forces. After 1 hour of simulation, the thrust and the ship velocity reaches a period of stabilization. During this period, the influence of the external forces associated with the wave and drag effects are observed, in this way the effects of pressure gradients become important causing increasing (reducing) of the ship velocity according with the increasing (reduction) of the wave velocity. On the situation with the thrust decreasing, the variations on the x and y components are not observed. On the other hand, for the situation with the increasing thrust the variations on the x and y components reflect on lateral deviations of the ship trajectory.
Transactions of the Royal Institution of Naval Architects Part A: International Journal of Maritime Engineering, 2011
The aim of this paper is to compare the heave and pitch motions for the S175 containership, travelling in head regular waves, obtained from frequency domain linear and time domain partly nonlinear potential flow analyses. The frequency domain methods comprise the pulsating and the translating, pulsating Green's function methods, with the relevant source distribution over the mean wetted surface of the hull. The time domain method uses the radiation and diffraction potentials related to the mean wetted surface, implemented using Impulse Response Functions (IRF), whilst the incident wave and restoring actions are evaluated on the instantaneous wetted surface. The calculations are carried out for a range of Froude numbers, and in the case of the partly nonlinear method for different wave steepness values. Comparisons are made with available experimental measurements. The discussion focuses on the necessity for a nonlinear approach for predicting the radiation potential and the possible numerical methods for its formulation.
Numerical Study on Hydrodynamics of Ships with Forward Speed Based on Nonlinear Steady Wave
Journal of Marine Science and Engineering, 2020
In this paper, an improved potential flow model is proposed for the hydrodynamic analysis of ships advancing in waves. A desingularized Rankine panel method, which has been improved with the added effect of nonlinear steady wave-making (NSWM) flow in frequency domain, is employed for 3D diffraction and radiation problems. Non-uniform rational B-splines (NURBS) are used to describe the body and free surfaces. The NSWM potential is computed by linear superposition of the first-order and second-order steady wave-making potentials which are determined by solving the corresponding boundary value problems (BVPs). The so-called mj terms in the body boundary condition of the radiation problem are evaluated with nonlinear steady flow. The free surface boundary conditions in the diffraction and radiation problems are also derived by considering nonlinear steady flow. To verify the improved model and the numerical method adopted in the present study, the nonlinear wave-making problem of a subm...
Volume 6: Ocean Engineering, 2011
The paper presents experimental results from model tests with a containership advancing in abnormal wave conditions and comparisons with numerical simulations. A nonlinear time domain method based on strip theory is used for the calculation of vertical ship responses induced by abnormal waves. This code combines the linear diffraction and radiation forces with dominant nonlinear forces associated with vertical response arising from Froude-Krylov forces, hydrostatic forces and shipping of green water. The time domain simulations are compared directly with experimental records from tests with a model of a container ship in deterministic waves for a range of Froude numbers. Extreme sea conditions were replicated by the reproduction of realistic abnormal waves like the New Year Wave and abnormal wave from North Alwyn. Head sea condition is considered and the comparisons include the wave elevation, the vertical motions of the ship and the vertical bending moment at midship.
Numerical Investigation of Motion Response of Two Model Ships in Regular Waves
In this paper, the sea keeping performances of two model ships in regular waves are studied by our in-house solver naoe-FOAM-SJTU based on OpenFOAM code package. Volume of Fluid (VOF) method is used to capture the free interface and Finite Volume Method (FVM) is adopted as the discretization scheme. Different wave conditions are set by the wave generation and damping module in the solver. The heave and pitch are simulated, and green water is found during the ship motion. The function of bulbous bow for that is discussed.
URANSE simulation for the Seakeeping of the KVLCC2 Ship Model in Short and Long Regular Head Waves
IOP Conference Series: Materials Science and Engineering, 2019
In the present study, the vertical motions and the added resistance in waves of the KVLCC2 ship model are predicted numerically in regular head wave, for a single wave height and different wave lengths, including long and short waves. The numerical simulation is performed by making use of the ISIS-CFD solver of the commercial software FineTM/Marine provided by NUMECA, where the discretization in space is based on finite volume method using unstructured grid. The unsteady RANSE are numerically solved, while the turbulence is modelled by making use of the k-ω SST model. The free-surface is captured through an air-water interface based on the Volume of Fluid method. For validation purposes, the computed solutions are compared with the available tank test data existing in the public domain. A systematic grid convergence study based on Richardson Extrapolation method is performed for a single wave case on three different grid resolutions, as an attempt of predicting the uncertainties in ...
2021
In this paper, the added wave resistance of an Ultra Large Container Ship (ULCS) in shallow water is investigated both experimentally and numerically. The experimental results come from a series of tests performed in the Towing Tank for Manoeuvres in Confined Water (co-operation Flanders Hydraulics Research and Ghent University) in Antwerp (Belgium) in 2016. Tests were executed for head and following waves, with two wave amplitudes, and using two different beam frames to attach the ship to the towing tank's carriage. One of the frames restrained the heave and pitch motions while the other one allowed the free motion of both. The results of experiments outline the proportionality of added resistance on the square of the wave amplitude in shallow water conditions. Moreover, the expected behaviour of added resistance at different wave lengths can be observed: in long waves, the added resistance is tightly related to the ship motions, while in short waves it achieves an asymptotic t...