Numerical Studies of Coupling Effect of Sloshing on 3D Ship Motions
- Jai Ram Saripilli (Indian Register of Shipping) | Debabrata Sen (Indian Institute of Technology)
- Document ID
- International Society of Offshore and Polar Engineers
- International Journal of Offshore and Polar Engineering
- Publication Date
- March 2017
- Document Type
- Journal Paper
- 27 - 35
- 2017. The International Society of Offshore and Polar Engineers
- Sloshing, finite volume method, ship motion, transient Green’s function method, coupled analysis
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- 68 since 2007
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The present work describes the development of an approach to study the problem of ship motions coupled with internal sloshing effects. A hybrid solution algorithm is developed that integrates a three-dimensional potential flow solver for ship motions into a viscous flow solver for sloshing loads. A three-dimensional time-domain forward-speed boundary element method (BEM), based on the transient Green’s function technique, is employed to capture the external ship hydrodynamics, while the open source finite volume method (FVM)-based solver, OpenFOAM, which incorporates an incompressible multiphase viscous flow model into an interface-capturing volume of fluid (VOF) technique, is employed to capture the internal sloshing hydrodynamics. After the individual solvers are validated against the experiments and other computations available in the literature, the solution from the coupled solver is discussed, and the influence of the coupling effects of sloshing loads on ship motions is brought out.
Sloshing is caused or initiated by ship motions under the action of waves that in turn affect ship motions. This coupling effect of sloshing on ship motions depends on the resonant characteristics of the sloshing flow in the tanks. The modified motions in turn affect the sloshing loads that are essential to evaluate the strength of the containment system. Conventionally, sloshing loads are determined by model experiments or computational fluid dynamics (CFD) simulations, where the precomputed ship motions obtained from a seakeeping analysis without consideration of the sloshing effects are used. This may lead to overestimation or underestimation of the loads.
To determine the effect of sloshing on ship motions and vice versa, a robust numerical tool capable of capturing the coupling effects is necessary. Several numerical studies have been attempted in the past in which potential flow and viscous flow solvers have been coupled. Kim (2002) used the 3D transient Green’s function-based method for computing ship motions and a fused deposition modeling (FDM)-based single phase solver for sloshing. Rognebakke and Faltinsen (2003) used a low-order boundary element method (BEM) for ship motions and a 2D simplified nonlinear multimodal approach for internal tank sloshing. Kim et al. (2004) used an impulse response function (IRF) method in conjunction with an FDM-based single phase solver and a smoothed-particle hydrodynamics (SPH)-based solver for the internal sloshing loads. The last two studies focused on the effect of sloshing in anti-rolling tanks.
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