scholarly journals A Study of Shipping Water Pressure on Deck by Two-Dimensional Ship Model Tests

1976 ◽  
Vol 1976 (140) ◽  
pp. 16-22 ◽  
Author(s):  
Kunio Goda ◽  
Takeshi Miyamoto
Keyword(s):  
Water Pressure ◽  
Model Tests ◽  
Two Dimensional ◽  
Ship Model ◽  
Shipping Water

Experimental Study of a Tanker Ship Squat in Shallow Water

2014 ◽  
Vol 66 (2) ◽  
Author(s):  
Mohammadreza Fathi Kazerooni ◽  
Mohammad Saeed Seif
Keyword(s):  
Experimental Study ◽  
Shallow Water ◽  
Experimental Approach ◽  
Model Tests ◽  
Ship Hull ◽  
Experimental Results ◽  
Shallow Waters ◽  
Towing Tank ◽  
Ship Model

One of the phenomena restricting the tanker navigation in shallow waters is reduction of under keel clearance in the terms of sinkage and dynamic trim that is called squatting. According to the complexity of flow around ship hull, one of the best methods to predict the ship squat is experimental approach based on model tests in the towing tank. In this study model tests for tanker ship model had been held in the towing tank and squat of the model are measured and analyzed. Based on experimental results suitable formulae for prediction of these types of ship squat in fairways are obtained.

Wave Loads on Floaters of Aquaculture Plants

2008 ◽  
Author(s):  
David Kristiansen ◽  
Odd M. Faltinsen
Keyword(s):  
Stokes Equations ◽  
Model Tests ◽  
Staggered Grid ◽  
Physical Parameters ◽  
Surface Zone ◽  
Two Dimensional ◽  
Wave Loads ◽  
Wave Load ◽  
Constrained Interpolation ◽  
Advection Term

This paper addresses wave loads on horizontal cylinders in the free surface zone by means of model tests and numerical simulations. This has relevance for the design of floating fish farms at exposed locations. Two model geometries were tested, where two-dimensional flow conditions were sought. The cylinders were fixed and exposed to regular wave trains. Wave overtopping the models were observed. A two-dimensional Numerical Wave Tank (NWT) for wave load computations is described. The NWT is based on the finite difference method and solves the incompressible Navier-Stokes equations on a non-uniform Cartesian staggered grid. The advection term is treated separately by the CIP (Constrained Interpolation Profile) method. A fractional and validation of the NWT is emphasized. Numerical results from simulations with the same physical parameters as in the model tests are performed for comparison. Deviations are discussed.

Studies on Resonant Water Motion Between a Ship and a Fixed Terminal in Shallow Water

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Trygve Kristiansen ◽  
Odd M. Faltinsen
Keyword(s):  
Shallow Water ◽  
Vertical Wall ◽  
Model Tests ◽  
Ship Model ◽  
Wave Flume ◽  
Wave Elevation ◽  
Resonant Behavior ◽  
Liquid Natural Gas ◽  
Sharp Corners ◽  
Hydrodynamical Problem

This work focuses on the hydrodynamical problem of a Liquid Natural Gas (LNG) carrier near a Gravity Based Structure (GBS) -type offshore terminal subject to incoming waves in medium deep to shallow water conditions. The work is restricted to 2D, and the ship is restrained from moving. The resonant behavior of the fluid in the gap between the ship and the terminal is investigated. The problem is investigated by means of a numerical model and model tests. Potential theory is assumed, and a linear as well as a nonlinear time-domain numerical wavetank based on a boundary element method with a mixed Eulerian–Lagrangian approach is implemented for this purpose. Model tests (near 2D) of a midship section near a vertical wall are carried out in a 26.5m long and 0.595m wide wave flume in model scale 1:70. In full scale the ship beam is 45m and the ship draft is 12m. The ship model is constructed in such a way as to avoid flow separation, i.e., no sharp corners. Several parameters are varied: water depth, wave period, and wave steepness. Wave elevation is measured at 12 locations.

scholarly journals Effects of seepage and weak interlayer on the failure modes of surrounding rock: model tests and numerical analysis

2019 ◽  
Vol 6 (9) ◽  
pp. 190790
Author(s):  
Jing Hu ◽  
Haijia Wen ◽  
Qilong Xie ◽  
Binyang Li ◽  
Qu Mo
Keyword(s):  
Failure Modes ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Model Tests ◽  
Surrounding Rock ◽  
Modes Of Failure ◽  
Geological Conditions ◽  
Weak Interlayer ◽  
Rock Model ◽  
Distribution Of Stress

The presence of weak interlayers and groundwater are common adverse geological conditions in tunnels. To investigate the modes of failure of rock masses surrounding tunnels owing to weak interlayers and groundwater, model tests and numerical simulations were conducted in this study based on two cases, and a model that considers only the weak interlayer was conducted for comparison. Based on the tests, differences between two models in terms of rock pressure, displacement, cracks and strain were analysed. The results reveal that the presence of groundwater has a significant effect on the space–time distribution of stress, displacement and cracks in the surrounding rock. Furthermore, based on the numerical model, the seepage field was analysed in terms of pore water pressure, permeability and the seepage process to understand the joint action of groundwater and weak interlayer on the failure mechanism of tunnels. The results show that the groundwater and interlayer complement each other to induce the failure mode of the surrounding rock. The water accelerates slip in the interlayer and the development of cracks. Conversely, low strength, muddy weak interlayers serve as the channels of water flow, resulting in deformations and cracks at different locations and different failure modes.

scholarly journals A theory of ice-sheet surges

1998 ◽  
Vol 44 (146) ◽  
pp. 104-118 ◽  
Author(s):  
A. C. Fowler ◽  
E. Schiavi
Keyword(s):  
Numerical Solution ◽  
Water Pressure ◽  
Ice Sheet ◽  
Simple Theory ◽  
Simplified Model ◽  
Two Dimensional ◽  
Basal Ice ◽  
Sophisticated Model

AbstractA simplified model of a two-dimensional ice sheet is described. It includes basal ice sliding dependent, on the basal water pressure, which itself is described by a simple theory of basal drainage. We show that this simple but sophisticated model predicts surges of the ice mass in realistic circumstances, and we describe these surges by solving the problem numerically. We also are able to describe some parts of the surge analytically. The numerical solution of the model is a delicate matter, and highlights pitfalls to be avoided if more complicated models are to be solved successfully.

Predicting Roll Damping for Barge-Type FPSO Using CFD

2019 ◽  
Author(s):  
Arjen Koop ◽  
Frédérick Jaouën ◽  
Xavier Wadbled ◽  
Erwan Corbineau
Keyword(s):  
Turbulence Model ◽  
Three Dimensional ◽  
Model Tests ◽  
Vortical Flow ◽  
Damping Coefficient ◽  
Physical Parameters ◽  
Two Dimensional ◽  
Roll Damping ◽  
End Effects ◽  
Hydrodynamic Damping

Abstract An accurate prediction of the non-linear roll damping is required in order to calculate the resonant roll motion of moored FPSO’s. Traditionally, the roll damping is obtained with model tests using decays or forced roll oscillation tests. Calculation methods based on potential flow are not capable of predicting this hydrodynamic damping accurately as it originates from the viscous nature of the fluid and the complex vortical flow structures around a rolling vessel. In recent years Computational Fluid Dynamics (CFD) has advanced such that accurate predictions for the roll damping can be obtained. In this paper CFD is employed to predict the roll damping for a barge-type FPSO. The objectives of the paper are to investigate the capability and accuracy of CFD to determine roll damping of an FPSO and to investigate whether two-dimensional calculations can be used to estimate the roll damping of a three-dimensional FPSO geometry. To meet these objectives, extensive numerical sensitivity studies are carried out for a 2D hull section mimicking the midsection of the FPSO. The numerical uncertainty for the added mass and damping coefficients were found to be 0.5% and 2%, respectively. The influence of the turbulence model was found to be significant for the damping coefficient with differences up to 14%. The 2D CFD results are compared to results from two-dimensional model tests. The calculated roll damping using the k-ω SST 2003 turbulence model matches the value from the experiments within 2%. The influence of various physical parameters on the damping was investigated through additional 2D calculations by changing the scale ratio, the roll amplitude, the roll period, the water depth, the origin of rotation and the bilge keel height. Lastly, three-dimensional calculations are carried out with the complete FPSO geometry. The 3D results agree with the 2D results except for the largest roll amplitude calculated, i.e. for 15 degrees, where the damping coefficient was found to be 7% smaller. For this amplitude end-effects from the ends of the bilge keels seem to have a small influence on the flow field around the bilge keels. This indicates that the 2D approach is a cost-effective method to determine the roll damping of a barge-type FPSO, but for large roll amplitudes or for different vessel geometries the 2D approach may not be valid due to 3D effects.

Estimation of Hydrodynamic Coefficients of a Nonlinear Manoeuvring Mathematical Model With Free-Running Ship Model Tests

2018 ◽  
Vol Vol 160 (A3) ◽  
Author(s):  
Haitong Xu ◽  
M A Hinostroza ◽  
C Guedes Soares
Keyword(s):  
Mathematical Model ◽  
System Identification ◽  
Model Tests ◽  
Loss Functions ◽  
Identification Algorithm ◽  
Hydrodynamic Coefficients ◽  
Global Optimization Algorithm ◽  
Identification Process ◽  
Ship Model ◽  
Free Running

Free-running model tests have been carried out based on a scaled chemical tanker ship model, having a guidance, control and navigation system developed and implemented in LabVIEW. In order to make the modelling more flexible and physically more realistic, a modified version of Abkowitz model was introduced. During the identification process, the model’s structure is fixed and its parameters have been obtained using system identification. A global optimization algorithm has been used to search the optimum values and minimize the loss functions. In order to reduce the effect of noise in the variables, different loss functions considering the empirical errors and generalization performance have been defined and implemented in the system identification program. The hydrodynamic coefficients have been identified based on the manoeuvring test data of free-running ship model. Validations of the system identification algorithm were also carried out and the comparisons with experiments demonstrated the effectiveness of the proposed system identification method.

Moving PIV/LDV System for Various Ship Model Tests in a Towing Tank

2010 ◽  
Author(s):  
Aria Yuliartha ◽  
◽  
Che-Chun Chang ◽  
Shi-tai Jian ◽  
Sheng-Jie Shih ◽  
...  
Keyword(s):  
Model Tests ◽  
Towing Tank ◽  
Ship Model
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