Research on Longitudinal Motion Prediction of Hybrid Monohull Considering Based on Numerical Simulation

2014 ◽  
Vol 716-717 ◽  
pp. 776-779
Author(s):  
Bo Tian ◽  
Hui Long Ren ◽  
Zhi Yuan Dong
Keyword(s):  
Numerical Simulation ◽  
Model Test ◽  
Potential Flow ◽  
Motion Prediction ◽  
Longitudinal Motion ◽  
Hydrodynamic Coefficients ◽  
Regular Waves ◽  
Damping Force ◽  
Main Component ◽  
Rans Method

The shape of hybrid monohull at the bow is quite complex and the viscosity force is the main component of the damping force in the drainage area of the bow when the ship moves in waves so that the result of the motion predicition by the traditional potential flow method is very different from the result of experiments. This paper tries to use new numerical compute method considering the effect of the viscosity to improve the precision of the sea keeping predicition. Based on the Reynolds Averaged N-S Equations (RANS) method, the paper takes a hrbrid monohull to compute the hydrodynamic coefficients. According to the result of model test, the prediction of the hybrid monohull’s the longitudinal motion in regular waves at speed of 18kn also indicates that RANS method can reflect viscid influence reducing the motion of hybrid monohull in waves.

Assessment of Latching Control for the Hemispheric Heaving Buoy Type Point Absorber With and Without Nonlinear Froude-Krylov Force Acting on the Buoy

2019 ◽  
Author(s):  
Sung-Jae Kim ◽  
Weoncheol Koo ◽  
Chul H. Jo
Keyword(s):  
Control Strategy ◽  
Potential Flow ◽  
Flow Theory ◽  
Hydrodynamic Performance ◽  
Hydrodynamic Coefficients ◽  
Damping Force ◽  
Hydraulic Power ◽  
Coulomb Damping ◽  
Point Absorber ◽  
Latching Control

Abstract In this study, a latching control strategy was utilized to increase the efficiency of a heaving buoy-type point absorber with a hydraulic Power take-off (PTO) system. For this purpose, the hydrodynamic performance of a floating buoy was analyzed based on the potential flow theory and Cummins equation. Nonlinear Froude-Krylov (FK) force according to instantaneous wetted surface of a buoy was calculated by a theoretical solution. The effect of the latching control on a point absorber was evaluated by considering PTO performance with hydrodynamic coefficients including nonlinear FK force. The hydraulic PTO system was modeled as an approximate coulomb damping force.

Hydrodynamic Coefficients of a Moored Semisubmersible in Waves

1992 ◽  
Vol 114 (1) ◽  
pp. 9-15 ◽  
Author(s):  
S. K. Chakrabarti ◽  
D. C. Cotter
Keyword(s):  
Model Test ◽  
Nonlinear Damping ◽  
Added Mass ◽  
Hydrodynamic Coefficients ◽  
Regular Waves ◽  
Initial Displacement ◽  
Slow Drift ◽  
Linear And Nonlinear ◽  
The Waves ◽  
Line Loads

The hydrodynamic coefficients of a semisubmersible undergoing slow-drift oscillation were determined through a model test. The semisubmersible model was moored in head seas, fore and aft, with linear springs which were pretensioned and never became slack during any test run. At the beginning of each test run, the vessel was held at an initial displacement from its equilibrium position and then released, and the resulting line loads were recorded. The semisubmersible was tested in still water and in regular waves. The amplitude of the waves at a given period was varied. The added mass and damping of the semisubmersible were determined from the decayed oscillation of the loads. The semisubmersible experienced both linear and nonlinear damping. The hydrodynamic coefficients obtained from the semisubmersible as functions of wave height and period are compared with those found previously on a tanker.

Comparison of Two Correction Methods for Predicting the Longitudinal Motion of the Hybrid Monohull

2011 ◽  
Vol 105-107 ◽  
pp. 2209-2212
Author(s):  
Xu Jie Wang ◽  
Shu Zheng Sun ◽  
Ji De Li
Keyword(s):  
Model Test ◽  
Engineering Application ◽  
The Other ◽  
Viscous Force ◽  
Longitudinal Motion ◽  
Hydrodynamic Coefficients ◽  
Viscous Effect ◽  
Test Results ◽  
Fluent Software ◽  
Better Than

Using traditional strip method to predict longitudinal motion of hybrid monohull, the results are very different from test results, it can not reflect the effect of built-up appendage by reason of ignoring viscous force. This paper calculated the hydrodynamic coefficients of the hybrid monohull with two correction methods, one considering the viscous effect with lateral flow theory, the other calculating the correction coefficients based on RANS equation by using FLUENT software, and then predicted the longitudinal motion by STF method. By comparing the predicted results with the model test results, it shows that, both of two correction methods can reflect the effect of built-up appendage, and can be used for predicting the longitudinal motion of hybrid monohull, the accuracy of the latter is obviously better than former, it has good value in engineering application.

On Roll Hydrodynamics of FPSO’s Fitted With Bilge Keels and Riser Balcony

2011 ◽  
Author(s):  
R. van ’t Veer ◽  
F. Fathi ◽  
J. G. Kherian
Keyword(s):  
Model Test ◽  
Potential Flow ◽  
Model Tests ◽  
Continuous Operation ◽  
Motion Prediction ◽  
Roll Motion ◽  
Test Results ◽  
Site Location ◽  
Cfd Simulations ◽  
Roll Damping

The topic of this paper is the roll motion prediction of ship-shaped FPSO’s, designed for continuous operation at site location. The maximum roll amplitude is a critical operability parameter which is difficult to predict accurately due to the nonlinear roll damping associated with the appendages. This paper contributes to the understanding of roll damping physics through model test results, CFD simulations and potential flow predictions. The model tests discussed concern two different Floating Production, Storage and Offloading (FPSO) units, designed by SBM as spread-moored units for operation offshore Brazil. The relevant roll damping appendages are the bilge keels on both sides and the submerged riser balcony on one side of the vessel. In particular the riser balcony complicates the motion prediction and was a main reason for the model tests and CFD investigation. The results presented focus on roll motion prediction in the frequency domain.

Numerical Simulation of Ship Collision and Validations With Experimental Results

2021 ◽  
Author(s):  
Xiangbiao Wang ◽  
Chun Bao Li ◽  
Ling Zhu
Keyword(s):  
Numerical Simulation ◽  
Model Test ◽  
Structural Damage ◽  
Added Mass ◽  
Ship Motion ◽  
Time Dependent ◽  
Structural Deformation ◽  
Structure Interaction ◽  
Ship Collision ◽  
Good Agreement

Abstract Ship collision accidents occur from time to time in recent years, and this would cause serious consequences such as casualties, environmental pollution, loss of cargo on board, damage to the ship and its equipment, etc. Therefore, it is of great significance to study the response of ship motion and the mechanism of structural damage during the collision. In this paper, model experiments and numerical simulation are used to study the ship-ship collision. Firstly, the Coupled Eulerian-Lagrangian (CEL) was used to simulate the fluid-structure interaction for predicting structural deformation and ship motion during the normal ship-ship collision. Meanwhile, a series of model tests were carried out to validate the numerical results. The validation presented that the CEL simulation was in good agreement with the model test. However, the CEL simulation could not present the characteristics the time-dependent added mass.

Diffraction Waves About an Advancing Wedge Model in Deep Water

1990 ◽  
Vol 34 (02) ◽  
pp. 105-122
Author(s):  
Hideaki Miyata ◽  
Makoto Kanai ◽  
Noriaki Yoshiyasu ◽  
Yohichi Furuno
Keyword(s):  
Numerical Simulation ◽  
Finite Difference ◽  
Finite Difference Method ◽  
Wedge Angle ◽  
Wave Pattern ◽  
Regular Waves ◽  
Nonlinear Characteristics ◽  
Diffracted Waves ◽  
Nonlinear Features ◽  
Incident Waves

The diffraction of regular waves by advancing wedge models is studied both experimentally and numerically. The nonlinear features of diffracted waves are visualized by wave pattern pictures and the formation is analyzed by the grid-projection method. The experimental observation indicates that the diffracted waves have a number of nonlinear characteristics similar to shock waves due to the interaction of incident waves with the advancing obstacle in the flow-field caused by the advancing motion. Bow waves of both oblique type and normal detached type are observed at remarkably lower Froude numbers than in the case of a ship in steady advance motion. Their occurrence systematically depends on the Froude number and the wedge angle. The numerical simulation of this phenomenon by a finite-difference method shows approximate agreement with the experimental results.

Numerical simulation of regular waves: Optimization of a numerical wave tank

2018 ◽  
Vol 170 ◽  
pp. 89-99 ◽  
Author(s):  
Fábio M. Marques Machado ◽  
António M. Gameiro Lopes ◽  
Almerindo D. Ferreira
Keyword(s):  
Numerical Simulation ◽  
Numerical Wave Tank ◽  
Regular Waves ◽  
Wave Tank ◽  
Numerical Wave

Study on Similar Skills of Dynamic Model Test Concerning Fluid-Structure Interaction for Water-Conveyance Tunnel in Soft Soil

2010 ◽  
Vol 29-32 ◽  
pp. 1458-1463 ◽  
Author(s):  
Jin Yun Liu ◽  
Jian Yun Chen
Keyword(s):  
Numerical Simulation ◽  
Model Test ◽  
Structural Model ◽  
Soft Soil ◽  
Fluid Structure Interaction ◽  
Similar Relationship ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Water Conveyance ◽  
Water Conveyance Tunnel

Three basic types of similar relationship between the prototype and the model for dynamic structural model test and dynamic destructive model test were proposed in corresponding literatures. At the time the situation where various similar relationships are applicable and the technique to ensure similarity for the different goal was discussed. Here the numerical simulation of model test of water-conveyance tunnel concerning fluid-structure interaction in soft soil is studied. Based on economy and practicability of selective material for model test, the similar relationship and the technique are proposed, which are validated through the example. The results of numerical simulation show: under the specific conditions, data of the model test can completely transfer to those of the prototype by use of this type of similar skill, and get more useful information. Some new ideas are introduced to keep the similarity of the hydro-structure structures.

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