scholarly journals A STUDY ON NUMERICAL ACCURACY FOR THE PREDICTION OF MOTION RESPONSES AND DRIFT FORCES OF MULTIPLE FLOATING BODIES

2002 ◽  
Vol 2002 (192) ◽  
pp. 289-298
Author(s):  
Yoshiyuki Inoue ◽  
Mir Tareque Ali
Keyword(s):  
Floating Bodies ◽  
Numerical Accuracy ◽  
Motion Responses ◽  
Multiple Floating Bodies ◽  
Drift Forces

Wave Drift Forces' Calculation on Two Floating Bodies Based on the Boundary Element Method—Attempt for Improvement of the Constant Panel Method

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Qiao Li ◽  
Yasunori Nihei
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Evaluation Method ◽  
Panel Method ◽  
Floating Bodies ◽  
Wave Drift ◽  
Wave Drift Forces ◽  
Multiple Floating Bodies ◽  
Drift Forces ◽  
Element Method

An improved constant panel method for more accurate evaluation of wave drift forces and moment is proposed. The boundary element method (BEM) of solving boundary integral equations is used to calculate velocity potentials of floating bodies. The equations are discretized by either the higher-order boundary element method or the constant panel method. Though calculating the velocity potential via the constant panel method is simple, the results are unable to accurately evaluate wave drift forces and moment. An improved constant panel method is introduced to address these issues. The improved constant panel method can, without difficulty, employ the near-field method to evaluate wave drift forces and moment, especially for multiple floating bodies. Results of the new evaluation method will be compared with other evaluation method. Additionally, hydrodynamic interaction between multiple floating bodies will be assessed.

Reduced-Order Time-Domain Simulation of Floating Bodies for Efficient Design Analysis

2015 ◽  
Author(s):  
Hyun Y. Kim ◽  
Stephanie L. Fitzpatrick ◽  
David C. Kring
Keyword(s):  
Memory Function ◽  
Computational Effort ◽  
Impulse Response Functions ◽  
Time Domain Simulation ◽  
Efficient Design ◽  
Floating Bodies ◽  
Order Model ◽  
Reduced Order ◽  
Multi Body ◽  
Multiple Floating Bodies

This paper describes the development and implementation of a reduced-order model to represent the hydrodynamic forces acting on a ship using Impulse-Response Functions (IRF). The approach will be conducted using Aegir, a timedomain seakeeping program that uses an advanced, Non-Rational Uniform B-Spline (NURBS) based, high-order boundary element method. The Cummins equation is slightly modified such that the memory function is decomposed into two terms: one for the impulsive velocity and the other term for the impulsive displacement. The present approach also further develops a method to simulate interactions between multiple floating bodies. The IRF convolutions for the free surface memory effect significantly reduce the computational effort compared to direct simulation. This will be demonstrated for both single and multi-body forward-speed, seakeeping simulations.

Effects of Motion Responses and Drift Forces on Side-by-Side Offloading Operations of FPSO

2019 ◽  
pp. 407-413 ◽  
Author(s):  
Mohammed Shihab Patel ◽  
Mohd. Shahir Liew ◽  
Zahiraniza Mustaffa ◽  
Abdurrasheed Said Abdurrasheed ◽  
Andrew Whyte
Keyword(s):  
Motion Responses ◽  
Drift Forces

Wave forces on multiple floating bodies

1982 ◽  
Vol 4 (1) ◽  
pp. 2-8 ◽  
Author(s):  
Akira Masumoto ◽  
Yoshio Yamagami ◽  
Ryuji Sakata
Keyword(s):  
Wave Forces ◽  
Floating Bodies ◽  
Multiple Floating Bodies

Drift of an articulated cylinder in regular waves

1984 ◽  
Vol 394 (1807) ◽  
pp. 363-385 ◽  
Keyword(s):  
Near Field ◽  
Second Order ◽  
Regular Waves ◽  
Floating Bodies ◽  
Wave Heights ◽  
Tilt Mode ◽  
The Mean ◽  
Wave Induced ◽  
Theoretical Results ◽  
Drift Forces

Potential flow theory is used to investigate the wave induced harmonic response and the mean drift of an articulated column in regular waves. The mean drift horizontal force is evaluated by means of the Stokes expansion to second order in wave steepness. Analyses based on both near field and far field formulations are shown to give identical expressions, provided that the second-order forces at the intersection between column and seabed are included in the near field approach. The latter have not been considered in previous studies concerned with drift forces on floating bodies. It is shown that the drift forces on a column, although of second order, can excite piech responses of first order: this is because articulated columns are designed to have a low natural frequency in the tilt mode, relative to wave frequencies. Comparison of the theoretical results with experimental data, from a model tested in regular waves, suggests reasonable agreement for the drift forces over a range of frequencies and two wave heights.

Experimental and Numerical Studies on Ship Motion Responses Coupled with Sloshing in Waves

2009 ◽  
Vol 53 (02) ◽  
pp. 68-82 ◽  
Author(s):  
Bo-Woo Nam ◽  
Yonghwan Kim ◽  
Dae-Woong Kim ◽  
Yong-Soo Kim
Keyword(s):  
Numerical Study ◽  
Experimental Studies ◽  
Impulse Response Function ◽  
Ship Motion ◽  
Computational Results ◽  
Floating Bodies ◽  
Motion Responses ◽  
Significant Difference ◽  
Response Amplitude Operators ◽  
Liquid Natural Gas

This study considers the motion responses of floating bodies in waves coupled with sloshing-induced internal forces and their effects on sloshing-induced impact loads. 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 considered models are a liquid natural gas floating production, storage, and offloading unit (LNG FPSO) with two partially filled tanks and a modified S175 hull with an antirolling tank. In the case of the LNG FPSO model, both numerical and experimental studies are carried out. Three degree-of-freedom motion responses are allowed in the presence of regular waves, and the measured response amplitude operators (RAOs) are compared with computational results. For the modified S175 hull, the computational results are compared with other existing computational results. It is observed that the present method provides a fair agreement with experimental and other numerical results, showing significant coupling effects on both motion responses and sloshing flows. The numerical study extends to the observation of pressure field inside the tanks, and a significant difference in internal pressure is also shown.

Hydrodynamic Interaction of Floating Structure in Regular Waves

2014 ◽  
Vol 66 (2) ◽  
Author(s):  
Hassan Abyn ◽  
Adi Maimun ◽  
Jaswar Jaswar ◽  
M. Rafiqul Islam ◽  
Allan Magee ◽  
...  
Keyword(s):  
Hydrodynamic Interaction ◽  
Oil And Gas ◽  
Irregular Waves ◽  
Source Distribution ◽  
Floating Bodies ◽  
Floating Structure ◽  
Distribution Method ◽  
Floating Structures ◽  
Motion Responses ◽  
Hydrodynamics Coefficients

Floating structures play an important role for exploring the oil and gas from the sea. In loading and offloading, motion responses of offshore floating structures are affected through hydrodynamic interaction. Large motions between floating bodies would cause the damage of moorings, offloading system and may colloid to each other. This research studies on hydrodynamic interaction between Tension Leg Platform (TLP) and Semi-Submersible (Tender Assisted Drilling (TAD)) in regular and irregular waves with scenario as follows: fixed TLP and 6-DOF floating semi-submersible and 6-DOF both TLP and semi-submersible. Under these conditions, hydrodynamics coefficients, mooring and connectors forces, motions and relative motions of TLP and Semi-Submersible will be simulated numerically by using 3D source distribution method. As the scope is big, this paper only presents model experiment of floating TLP and semi-submersible in the regular wave. The experiment is carried out in the UTM Towing Tank.

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