CFD applications for Ballast water management studies

The International Conference on Marine and Freshwater Environments, 2014

Transportation of oil and gas and oil spills are two potential risks posed to the marine environment. This paper mainly focuses on the use of Computational Fluid Dynamics (CFD) at Oceanic Consulting Corporation (OCC). With OCC's extensive CFD experience in Marine Engineering, it is expected that we could expand our expertise into the area of oil spill forecast and response or other related areas. Under support of the Atlantic Innovation Fund (AIF), Oceanic has been engaged in a project "Numerical Simulation of Hydrodynamic Loads for the Safe Production and Transportation of Oil and Gas in Harsh Marine Environments" since 2008. This paper presents some CFD studies taken from this project, which includes: 1) 3-dimension flow simulation; 2) Sloshing prediction of a U-tube tank in a vessel; and 3) Moored structure motion in waves and visualization. It also includes an introduction to some commercial CFD and in-house codes used in Oceanic.

2018

This paper presents the numerical investigation of ship resistance of Indonesian traditional fishing vessel. The Open-source computational fluid dynamics (CFD) library, OpenFOAM, was used to predict three dimensional, incompressible, unsteady RANS equations for the ship resistance. The volume of fluid (VOF) method is used to predict the resistance. InterFoam solver is adopted to solve the computational problem. The KCS model was calculated and compared to the experimental result for validating the solver and relatively good agreement is achieved, then can be used to simulate the present model. The present model was using Indonesian traditional fishing vessel from the north and south coastal of Java island. The water condition in this study is in calm water condition and the same Froude number (Fn) for both models. As a result, the presented model for preliminary total resistance prediction in advance of the evaluation of the traditional fishing vessel performances.<br>

Polish Maritime Research, 2019

On inland waterways the ship resistance and propulsive characteristics are strictly related to the depth of the waterway, thus it is important to have an understanding of the influence of water depth on ship hydrodynamic characteristics. Therefore, accurate predictions of hydrodynamic forces in restricted waterways are required and important. The aim of this paper is investigating the capability of the commercial unsteady Reynolds–Averaged Navier–Stokes (RANS) solver to predict the influence of water depth on ship resistance. The volume of fluid method (VOF) is applied to simulate the free surface flow around the ship. The hull resistance in shallow and deep water is compared. The obtained numerical results are validated against related experimental studies available in the literature.

Proceedings of Symposium on Analyses of Strongly Nonlinear Flows around Moving Boundaries

A numerical method for the prediction of hydrodynamic performance of a trimaran vessel is developed and it is validated through the comparison with experiments. The unsteady Reynolds-averaged Navier-Stokes equations are solved with the density function for the free surface treatment. The multi-block grid system is used to cope with the complicated geometry around a practical trimaran vessel with a long bulb and a transom stern. Using this method, flows around a trimaran vessel are simulated in steadily towed conditions. In order to evaluate seakeeping performance, the motion simulations in incident waves are carried out with heave, roll and pitch motions being set free. The experiments are conducted for the condition of steady straight condition and the drag, the attitude and the transverse wave profiles are measured. The experimental and numerical data, especially the transverse wave profiles, agrees well. Thus, the availability of the present method is demonstrated by these simulations.

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.

Strojarstvo Casopis Za Teoriju I Praksu U Strojarstvu, 2011

CFD Letters, 2021

The numerous ship accidents at sea have usually resulted in tremendous loss and casualties. To prevent such disastrous accidents, a comprehensive investigation into reliable prediction of seakeeping performance of a ship is necessarily required. This paper presents computational fluid dynamics (CFD) analysis on seakeeping performance of a training ship (full scale model) quantified through a Response of Amplitude Operators (RAO) for heave and pitch motions. The effects of wavelengths, wave directions and ship forward velocities have been accordingly taken into account. In general, the results revealed that the shorter wavelengths (l/L ? 1.0) have insignificant effect to the heave and pitch motions performance of the training ship, which means that the ship has good seakeeping behavior. However, the further increase of wavelength was proportional with the increase of RAO for her heave and pitch motions; whilst it may lead to degrade her seakeeping quality. In addition, the vertical m...

In this study, a 3D potential flow, panel method based CFD tool called AEGIR™ was assessed for predicting bare hull resistance and seakeeping performance. The program was run on mid-range personal computers, and analyses were performed on few different hullforms including the Joint High Speed Sealift (JHSS) monohull, a catamaran, a trimaran and a hard-chined semi-displacement monohull. Two different bow configurations, an elliptical shaped bulb and a gooseneck shaped bulb, were considered for the JHSS monohull bare hull resistance. For the catamaran and trimaran hullforms, the demihull and the center hull alone configurations were also considered for bare hull resistance. Measured data from model tests was used as a benchmark for validation. The focus was mainly on bare hull resistance with a very limited study on seakeeping. For all the hullforms and configurations, the coefficient of residuary resistance, sinkage and trim over a range of Froude numbers in calm water were obtained in AEGIR™ and compared with model test results. A limited set of seakeeping runs were performed in AEGIR™ on JHSS Monohull with gooseneck bulb and the catamaran demihull to obtain heave and pitch RAOs in regular head sea waves.

2014

Although CFD computation can predict resistance for conventional vessels with reliable accuracy at deep water condition, its predictive capability at shallow water condition is still unclear. One of the main objective of this study is to assess the accuracy of CFD computation for this kind of configuration and attempt to identify physical phenomena poorly modeled in the simulation. Shallow water resistance and squat are predicted for two different ship models, namely the DTC container ship, and the KVLCC2 tanker. Numerical uncertainty related to grid density, turbulence model as well as near wall turbulence model treatment will be investigated. Computation at full scale is also performed for the container ship to check the scale effect in ship squat prediction.