Numerical simulation of large commercial ship navigation on Paraná river, Argentina (original) (raw)
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Procedia Engineering, 2017
Wave wash is a hydrodynamic tool which explains ship generated waves and its impacts on shore and shore erosion. This paper describes that wave wash is an important factor to impose ship speed restriction and selecting speed for any shallow and narrow waterway. Relationships among ship speed, water depth, wave height, time period and wave energy have been established. Speed and depth conditions have been classified into four groups: Sub-Critical (F h < 0.75), Trans-Critical (0.75 < F h < 1.0), Critical (F h = 1.0) and Super-Critical (F h > 1.0). It is focused on waves generated by the ships to observe the maximum permissible speed for a vessel operated in a particular shallow and narrow water way. Empirical Formulae have been employed to find out maximum wave heights in relation with ship generated wave period, speed and other parameters. Maximum theoretical wave heights have been compared with wave wash criteria. These wave heights have also been compared with CFD results from potential flow solver and some commercial software. A case study has been done for a particular shallow and narrow waterway of Bangladesh. A vessel operated in that particular waterway had been selected for observing wave wash phenomena. Comparisons among theoretical results from different empirical equations, CFD results and different speed ranges have been done on which a model has been proposed to determine highest permissible ship speed in a shallow and narrow waterway. When a ship moves around critical speed range, wave wash becomes dominant.
Numerical study of viscous wave-making resistance of ship navigation in still water
Journal of Marine Science and Application, 2014
The prediction of a ship's resistance especially the viscous wave-making resistance is an important issue in CFD applications. In this paper, the resistances of six ships from hull 1 to hull 6 with different hull forms advancing in still water are numerically studied using the solver naoe-FOAM-SJTU, which was developed based on the open source code package OpenFOAM. Different components of the resistances are computed and compared while considering two speed conditions (12 kn and 16 kn). The resistance of hull 3 is the smallest while that of hull 5 is the largest at the same speed. The results show hull 3 is a good reference for the design of similar ships, which can provide some valuable guidelines for hull form optimization.
Monohull ship hydrodynamic simulation using CFD
International Journal of Mathematics in Operational Research, 2019
This research analyses the performance of a ship monohull at Galapagos real conditions using ANSYS FLUENT. In order to achieve these analyses, tide charts at Santa Cruz Island coast in Galapagos Islands were considered, since similar motorboats provide services as taxi boats in this area. These analyses were made in order to validate ships behaviour existing in Galapagos Islands. In addition, through simulation is not necessary to build these ships, in a way to obtain same results using less economic and technical resources. The hydrodynamic analysis of a monohull was simulated in static and dynamic conditions. Static analysis considers water and air flows hitting the boat bow which is resting (anchored boat). While dynamic analysis considers both the boat and water flow speed (sailing boat). Main results were: static and dynamic pressures, water height achieved by flow and ship speed variation, turbulence intensity, and simulation convergence residuals.
2018
There are very shallow water regions in Dhaka-Chittagong route of Bangladesh where inland vessels having draft 3.8 meter or more can not operate at its design speed even on high-tide all through the dry season. This thesis work presents hydrodynamic analysis of a 158 TEU container ship by a 3D numerical simulation using SHIPFLOW software to find out resistance, sinkage, trim and squat and suggests how to operate the vessel in very shallow water regions. To validate the computational results, a benchmark KRISO Container Ship (KCS) hull is used. Moreover, the flow around a 158 TEU container ship is simulated in deep water at different Froude numbers and the computed results are compared with experimental results for validation. Then, the flow around 158 TEU container ship is simulated in medium deep, shallow and very shallow water at different Froude numbers to obtain the resistance, sinkage, trim and squat values. The present squat obtained (subtracting deep water sinkage from shallo...
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 ...
Applied Ocean Research, 2019
Analysis of a craft with two degrees of freedom (2DOF) consumes time more than simulation of a craft with a fixed trim condition; therefore in most of the previous researches fixed trim condition is taken into account to analyze the flow field around a craft in shallow water and head sea wave conditions. In this paper numerical simulation of Reynolds Average Naiver Stokes (RANS) equations are used to analyze the motion of DTMB 62 model 4667-1 planing vessel in calm water and head sea waves in both deep and shallow water with two degrees of freedom (heave and pitch). For this purpose, a finite volume ANSYS-FLUENT code is used to solve the Navier-Stokes equations for the simulation of the flow field around the vessel. In addition, an explicit VOF scheme and SST k-ω model is used with dynamic mesh scheme to capture the interface of a two-phase flow and to model the turbulence respectively in the 2DOF model. Regarding the results, reducing the wavelength and also the depth of the water can increase the drag force. Also comparing the results of a fixed trim vessel with the results of a free to sink and trim one in calm water shows a difference of approximately 50% in the drag force in shallow water.
A WAVE MODEL FOR SIMULATING VESSEL EFFECTING SHALLOW WATER WAVES IN A MARITIME SIMULATOR (Thesis)
One important area of Maritime Simulations is the Wave effects of the ocean. Whilst there is significant work done in modeling deep ocean waves, the area of shallow water wave modeling has taken precedence in recent times. The objective of this thesis is, to study the possibilities of overcoming the barrier of high computation shallow water wave models that cannot be used for real time applications. Quoting from literature there exists three main approaches to model ocean waves: 1) Geometrical Description Models(constructed using periodic functions), 2) Spectral Models (using empirical data from Oceanic researches) & 3) Physical based models (from Computational Fluid Dynamics(CFD) based on numerical models). One key interest of this research is towards models that are able to achieve high accuracy in terms of the wave properties; thus guiding the user in making critical decisions and to predict close to real wave energy effects. It is noteworthy that only the approach of numerically solved physical based models (from the 3 approaches mentioned above) can provide wave parameters with high accuracy. Hence, this experiment is constrained to such physically based numerical models. All such models available for shallow-water simulations are inherently limited to not considering the depth of the water volume. Thus, the main focus of this thesis is towards a wave model that considers "depth" as an integral parameter in its calculations. The challenge imposed by such accurate models is the computation complexity that results in long processing time. Hence, they are not the most suitable choice for real-time simulators. This thesis experiments the possibility of a solution to this problem by restricting the simulation area to only that which has an impact on the vessel and by introducing cell reductions. The results obtained within the duration of this study, reveal that maintaining an optimal accuracy with such mesh-restrictions is not feasible and further efforts needs to be put in terms of parallel/gpu processing, profiling & etc.
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.
Numerical study on motions of a containership on head waves
IOP Conference Series: Materials Science and Engineering
Seakeeping performance represents an important chapter in the study of ship hydrodynamics. Computation of ship motions, amplitudes and accelerations conducts to the prediction of ship safety and security during operation. The experimental measurements of ship motions on regular waves are considered accurate methods, but still expensive. The paper presents the study of motions of a container ship in head regular and irregular waves. The 3D numerical analysis is performed based on BEM boundary element method, a CFD computational fluid dynamics method. In the numerical approach, seakeeping analysis was performed by using potential flow method. The comparison of numerical results for heave and pitch motions with the benchmark experimental tests reveals the accuracy and the validation of the numerical method. The numerical CFD-BEM investigation of ship motions at two forward speeds, 12 respectively 24 knots, were performed for the ship length to wavelength ratio in a range of 0.5-1.95. Based on the irregular wave results and by seakeeping limit criteria, the container ship navigation limits in head waves are analysed. The study results are pointing out good agreement between numerical and experimental models, the methodology being for practical design.
Computation of Hydrodynamic Characteristics of Ships Using CFD
International Journal of Materials, Mechanics and Manufacturing
This paper investigates various hydrodynamic characteristics of two conventional ships namely Wigley hull and Series 60 ship by commercial CFD software named Shipflow. Zonal approach is applied to incorporate 'potential flow solver' in the region outside the boundary layer and wake, 'boundary layer solver' in thin boundary layer region near the hull and 'Navier Stokes solver' in the wake region successively. Finally free-surface wave pattern, wave elevation, pressure coefficient on hull, boundary layer streamline and different resistance components at different speeds are computed and validated by comparing with experimental results.