Comparative Study on the Wave Impact Load in a Sloshing Tank

2004 ◽  
Author(s):  
J. H. Kyoung ◽  
J. W. Kim ◽  
K. J. Bai
Keyword(s):  
Free Surface ◽  
Impact Load ◽  
Three Dimensional ◽  
Free Surface Flow ◽  
Surface Flow ◽  
Wave Impact ◽  
Time Step ◽  
Surface Conditions ◽  
Nonlinear Free Surface ◽  
The Impact

Wave impact load occurring in a liquid storage tank during a sloshing motion is numerically simulated. Due to a violent sloshing, an excessive impact load can cause a critical damage to the tank structure. Recently this type of the accidents are reported and the problem becomes an important research topic in LNG (Liquefied Natural Gas) Tanker and FPSO (Floating Production Storage Offloading) design. To predict the sloshing impact load, Morison’s formula could be used for a practical reason. But using the Morison formula may provide directly an inaccurate estimation for the impact load because this formula is based on the linear model in the present nonlinear dominating phenomena. In this study, the wave impact load on the structure is obtained by imposing the exact nonlinear free surface conditions numerically and compared with that predicted by Morison’s formula. As a numerical method, a three-dimensional free surface flow in a tank is formulated in the scope of potential flow theory with the nonlinear free-surface conditions. A finite-element method based on Hamilton’s principle is employed as a numerical scheme. The problem is treated as an initial-value problem. The nonlinear problem is numerically solved through an iterative method at each time step.

A Finite Element Method for a Nonlinear Sloshing Problem

2003 ◽  
Author(s):  
J. H. Kyoung ◽  
J. W. Kim ◽  
K. J. Bai
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Free Surface ◽  
Impact Load ◽  
Surface Condition ◽  
Free Surface Flow ◽  
Surface Flow ◽  
Time Step ◽  
Nonlinear Sloshing ◽  
Element Method

A nonlinear sloshing problem in LNG tanker is numerically simulated. During excessive sloshing, the sloshing-induced impact load can cause a critical damage on the tank structure. Recently, this problem became one of important issues in FPSO design. A three-dimensional free surface flow in a tank is formulated in the scope of potential flow theory. The exact nonlinear free surface condition is satisfied numerically. A finite-element method based on Hamilton’s principle is employed as a numerical scheme. The problem is treated as an initial-value problem. The computations are made through an iterative method at each time step. The hydrodynamic loading on the pillar in the tank is computed and compared with other results.

Studying the Impact of Unstructured Mesh Adaptation on Free Surface Flow Simulations

2009 ◽  
Author(s):  
Olivier Allain ◽  
Damien Gue´gan ◽  
Fre´de´ric Alauzet
Keyword(s):  
Free Surface ◽  
Message Passing ◽  
Three Dimensional ◽  
Free Surface Flow ◽  
Two Dimensions ◽  
Surface Flow ◽  
Mesh Adaptation ◽  
Message Passing Algorithm ◽  
Dimensional Simulation ◽  
The Impact

Engineering offshore problems require a continuous progress in the simulation of systems coupling structures and fluids with interfaces. The needs concern complex interface motions and fluid-structure interaction with slamming. The proposed methodology combines, in a parallel message passing algorithm, a level set based interface tracking, a standard finite element projection method on unstructured meshes and a dynamic mesh adaptation process for time dependent problems. This numerical method is applied to the study of a wedge impacting a free surface in two dimensions [1, 2] and the three-dimensional simulation of a breaking water column which impacts an obstacle [3] for which experimental results are available.

Surface Ship Total Resistance Prediction Based on a Nonlinear Free Surface Potential Flow Solver and a Reynolds-Averaged Navier-Stokes Viscous Correction

2007 ◽  
Vol 51 (01) ◽  
pp. 47-64
Author(s):  
James C. Huan ◽  
Thomas T. Huang
Keyword(s):  
Free Surface ◽  
Surface Potential ◽  
Potential Flow ◽  
Free Surface Flow ◽  
Surface Flow ◽  
Navier Stokes ◽  
Total Resistance ◽  
Flow Solver ◽  
Resistance Prediction ◽  
Nonlinear Free Surface

A fast turnaround and an accurate computational fluid dynamics (CFD) approach for ship total resistance prediction is developed. The approach consists of a nonlinear free surface potential flow solver (PShip code) with a wet-or-dry transom stern model, and a Reynolds-averaged Navier-Stokes (RANS) equation solver that solves viscous free surface flow with a prescribed free surface given from the PShip. The prescribed free surface RANS predicts a viscous correction to the pressure resistance (viscous form) and viscous flow field around the hull. The viscous free surface flow solved this way avoids the time-consuming RANS iterations to resolve the free surface profile. The method, however, requires employing a flow characteristic-based nonreflecting boundary condition at the free surface. The approach can predict the components of ship resistance, the associated wave profile around the hull, and the sinkage and trim of the ship. Validation of the approach is presented with Wigley, Series 60 (CB = 0.6), and NSWCCD Model 5415 hulls. An overall accuracy of ±2% for ship total resistance prediction is achieved. The approach is applied to evaluating the effects of a stern flap on a DD 968 model on ship performance. An empirical viscous form resistance formula is also devised for a quick ship total resistance estimate.

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