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Collaborating Authors
Results
Study On Coupling Effects of Sloshing And Ship Motion
Kim, Yonghwan (Department of Naval Architecture & Ocean Engineering, Seoul National University) | Bo-Woo, Nam (Department of Naval Architecture & Ocean Engineering, Seoul National University) | Dae-Woong, Kim (Ship & Ocean R&D Institute, Daewoo Shipbuilding & Marine Engineering Co., Ltd.) | Yung-Bum, Lee (Ship & Ocean R&D Institute, Daewoo Shipbuilding & Marine Engineering Co., Ltd.) | Jung-Hwan, Lee (Ship & Ocean R&D Institute, Daewoo Shipbuilding & Marine Engineering Co., Ltd.)
ABSTRACT In the present study, the coupling effects of ship motion and sloshing is considered. The linear ship motion is solved using an impulse response function (IRF) method, while the nonlinear sloshing flow is simulated using a finite difference method. The wave-induced and sloshing-induced forces and moments are added up for motion excitation, and the corresponding linear ship motion is obtained in the time domain. The present scheme is applied for the roll motion of a modified S175 hull with rectangular anti-rolling tank. Due to the nonlinearity of sloshing flow, it is found that the ship motion is strong sensitive to wave slope. INTRODUCTION The present study considers the coupling effects of sloshing and ship motion. In particular, the study focuses on the nonlinear effects of sloshing flow in the linear ship motion. There are some existing studies on the coupling analysis, e.g. Dillingham (1981), Kim (2002), Rognebakke and Faltinsen (2003), and Newman (2005). The recent studies on the coupled problem can be categorized into two approaches; the frequency-domain approach (e.g. Newman, 2005) and the time-domain approach (e.g. Kim, 2002). According to existing studies, the assumption of linear ship motion seems enough in the coupled analysis. However, the linear sloshing flow is not valid in many engineering problems. Therefore, the nonlinear sloshing flow should be properly considered for coupling with the ship motion. In the present study, an impulse-response function (IRF) is applied for the analysis of ship motion in the time domain. Since CFD-type methods require a great effort to solve the ship motion alone, a more efficient method is needed when the coupling problem is considered. In the realm of linear theory, the IRF approach is enough for this purpose. The IRF approach adopts the inverse Fourier transform of the frequency-domain solution (Cummins, 1962).
- Europe (0.46)
- North America > United States > California (0.28)
ABSTRACT A smoothed particle hydrodynamics (SPH) method is applied for simulating violent sloshing flows in two-dimensional tanks. The SPH method based on the Lagrangian formulation shows realistic behavior with extreme fluid deformation, fragmentation and reunification. In the present study, boundary conditions are improved and re-initialization is used for the prediction of stable pressure field. Numerical simulations are performed for various water depth and frequencies, and the results are compared with existing experimental data and the results of a finite difference method. The comparison shows fair agreement. INTRODUCTION Many studies on ship sloshing problem were carried out in 1970's and early 1980's for the design of LNG carriers. Recently, the demand of sloshing analysis is increasing again, mostly due to the design of larger LNG carriers and LNG FPSOs. In the present study, a smooth particle hydrodynamics (SPH) is applied for two-dimensional violent sloshing flows. After the pioneering work of Monaghan(1994) for water wave problem, the SPH method has been applied for various free surface problems, especially for strongly nonlinear wave problems. Songdong(2002) solved a pressure-Poisson equation, not the state equation, and Colagrossi et al.(2003) considered both one-phase and two-phase flow model to study sloshing and wave problems. They also introduced a re-initialization technique to obtain stable solution. Iglesias et al.(2004) applied the SPH method to 3-D sloshing flows. Oger(2005) proposed a pressure-sensor concept to evaluate stable local pressure, and introduced the results of 2-D wedge entry problem using the SPH method. The present study, the algorithm based on the assumption of weakly compressible fluid is applied. For the implementation of boundary condition, the concept of ghost particles is adopted. Furthermore, to avoid unphysical large pressure oscillations in space and time, the density field is re-initialized using an accurate interpolation scheme.
- Reservoir Description and Dynamics > Reservoir Simulation (1.00)
- Facilities Design, Construction and Operation > Natural Gas Conversion and Storage > Liquified natural gas (LNG) (0.94)
- Data Science & Engineering Analytics > Information Management and Systems (0.89)
- Reservoir Description and Dynamics > Fluid Characterization > Fluid modeling, equations of state (0.87)