Higher Order Approximations of Multi-Body Hydrodynamic Interactions

2003 ◽  
pp. 201-209
Author(s):  
A. Satoh
Keyword(s):  
Higher Order ◽  
Hydrodynamic Interactions ◽  
Multi Body

A Numerical Study on Hydrodynamic Interactions Between Large Numbers of Multiple Floating Bodies

2003 ◽  
Author(s):  
Yoshiyuki Inoue ◽  
Mir Tareque Ali
Keyword(s):  
Numerical Study ◽  
Computer Code ◽  
Hydrodynamic Forces ◽  
Hydrodynamic Interactions ◽  
Physical Aspect ◽  
Floating Bodies ◽  
Coupled Equations ◽  
Large Numbers ◽  
Exciting Forces ◽  
Multi Body

This paper investigates the hydrodynamic interactions between large numbers of multiple bodies floating in each other’s close vicinity. The physical aspect of hydrodynamic interaction is rather complicated and numerically sound scheme is highly recommended to study this complex phenomenon. In the present study, the 3D sink-source method has been adopted to determine the hydrodynamic forces by taking into account the effect of hydrodynamic interactions among the different floating bodies, and the coupled equations of motions are solved directly. The validation of the computer code developed for this purpose has been justified by comparing the present results with that of the published ones for simple geometrical shaped floating bodies. The numerical computations have been carried out for different numbers of various freely floating multi-body systems and the hydrodynamic interactions between the floating bodies have been studied by calculating the hydrodynamic forces, first order wave exciting forces and motion responses. Finally some conclusions have been drawn on the basis of the present analysis.

Time Domain Turret Load and Motion Analyses for a FPSO

2020 ◽  
Author(s):  
Hyoungchul Kim ◽  
Bonjun Koo ◽  
Johyun Kyoung
Keyword(s):  
Time Domain ◽  
Interaction Model ◽  
Hydrodynamic Interactions ◽  
Test Results ◽  
Mechanical Coupling ◽  
Body Interaction ◽  
Nonlinear Springs ◽  
Frictional Damping ◽  
Multi Body ◽  
Fully Coupled

Abstract Fully coupled time domain turret/FPSO simulations are conducted using TechnipFMC proprietary software MLTSIM. To analyze hydrodynamic interactions and mechanical coupling effects between an FPSO and its turret, a multi-body interaction model is developed and analyzed. In the multi-body interaction model, full coupled hydrodynamic interactions are considered, and the bearing connections are modeled with nonlinear springs and frictional damping. The global performance analysis results are systematically compared with model test results (Kim et al. [1]), and hydrodynamic loads and mechanical coupling loads on the turret are presented in this paper.

scholarly journals Effects of Gap Resonance on the Hydrodynamics and Dynamics of a Multi-Module Floating System with Narrow Gaps

2021 ◽  
Vol 9 (11) ◽  
pp. 1256
Author(s):  
Mingsheng Chen ◽  
Hongrui Guo ◽  
Rong Wang ◽  
Ran Tao ◽  
Ning Cheng
Keyword(s):  
Damping Ratio ◽  
Normal Wave ◽  
Hydrodynamic Interactions ◽  
Period Range ◽  
Artificial Damping ◽  
Potential Applications ◽  
Floating System ◽  
Parametric Studies ◽  
Multi Body ◽  
Narrow Gaps

Multi-module floating system has attracted much attention in recent years as ocean space utilization becomes more demanding. This type of structural system has potential applications in the design and construction of floating piers, floating airports and Mobile Offshore Bases (MOBs) generally consists of multiple modules with narrow gaps in which hydrodynamic interactions play a non-neglected role. This study considers a numerical model consisting of several rectangular modules to study the hydrodynamics and dynamics of the multi-module floating system subjected to the waves. Based on ANSYS-AQWA, both frequency-domain and time-domain simulations are performed to analyze the complex multi-body hydrodynamic interactions by introducing artificial damping on the gap surfaces. Parametric studies are carried out to investigate the effects of the gap width, shielding effects of the multi-body system, artificial damping ratio on the gap surface, and the dependency of the hydrodynamic interaction effect on wave headings is clarified. Based on the results, it is found that the numerical analysis based on the potential flow theory with artificial damping introduced can produce accurate results for the normal wave period range. In addition, the effects of artificial damping on the dynamics and connector loads are investigated by using a simplified RMFC model. For the case of adding an artificial damping ratio of 0.2, the relative heave and pitch motions are found to be reduced by 33% and 50%, respectively. In addition, the maximum cable and fender forces are found to be reduced by 50%, compared with the case without viscosity correction.

Hydrodynamics Interactions on Vortex-Induced Motions of a Multi-Body Floating System

2019 ◽  
Author(s):  
Yibo Liang ◽  
Longbin Tao
Keyword(s):  
Horizontal Plane ◽  
Numerical Data ◽  
Hydrodynamic Interactions ◽  
Gap Ratio ◽  
Floating System ◽  
Preliminary Study ◽  
Drag And Lift ◽  
Lock In ◽  
Multi Body ◽  
Floating Platforms

Abstract In this study, numerical analysis has been carried out to investigate the hydrodynamic interactions of two multi-columns platforms. The objective of the work is to preliminarily evaluate the feasibility of a tension-leg-platform (TLP) dry tree unit (DTU) with tender assisted drilling (TAD) from the aspect of vortex-induced motions, characterized by the current. Two multi-columns floating platforms with a small gap ratio (28% of the overall platform width) are numerically simulated with the scenario of 3 degree-of-freedom (DOF) on the horizontal plane (including transverse, in-line and yaw motions). A comprehensive numerical simulation was conducted to examine the hydrodynamics interactions due to the flow over two floating platforms. Horizontal plane motions including transverse, in-line and yaw motions as well as drag and lift forces on both structures are discussed. The numerical data on the multi-body VIM interactions within the “lock-in” region will serve as a preliminary study for future coupled motions analysis of the TLP-TAD system design.

Time-Domain Simulation of a Multi-Body Floating System in Waves

2010 ◽  
Author(s):  
Xiaochuan Yu ◽  
Jeffrey M. Falzarano ◽  
Zhiyong Su
Keyword(s):  
Time Domain ◽  
Impulse Response Function ◽  
Hydrodynamic Interactions ◽  
Time Domain Simulation ◽  
Single Vessel ◽  
Close Proximity ◽  
Floating System ◽  
Response Amplitude Operators ◽  
Multi Body ◽  
Coefficient Method

It is important to study multi-body dynamics when analyzing the transfer of cargo between ships and platforms at sea. The hydrodynamic interactions should be considered in an accurate way to predict the relative motions between them. In this paper, the response amplitude operators (RAOs) of a single vessel will be compared with those of a multi-body system, considering different spacing between them. Further, the coupled hydrodynamic interactions among multiple vessels in close proximity are studied. Various levels of approximation, including the constant coefficient method (CCM) and the impulse response function (IRF) method, are employed to model the hydrodynamic interactions. Finally, the comparison between a single vessel and multi-body time domain simulation is also given.

Wave Drift Forces on Three Barges Arranged Side by Side in Floatover Installation

2013 ◽  
Author(s):  
Xin Xu ◽  
Jianmin Yang ◽  
Xin Li ◽  
Haining Lu
Keyword(s):  
Near Field ◽  
Field Method ◽  
Hydrodynamic Interactions ◽  
Body System ◽  
Wave Drift ◽  
Single Body ◽  
Motion Responses ◽  
Wave Drift Forces ◽  
Multi Body ◽  
Drift Forces

Floatover is a new method for installing integrated topside of a spar platform. It has several obvious advantages such as less time and cost compared with derrick lifting. In general, the floatover installation consists of three procedures: firstly a single barge is used for long-distance transportation of the topside in order to get good stability; secondly two barges take place of the single barge for floatover installation near the operating site; finally the topside is transferred from the two barges to the spar hull and the installation is completed. Between the first and second procedures, the case occurs that the single transportation barge is sided left and right by two floatover barges in the second procedure with close proximity. This case is concerned by many designers and operators for the security problem brought by possible large relative motions and forces of the three barges in side by side configuration. The hydrodynamics of side-by-side barges are much more complex than that of a single barge in waves. In numerical simulation, it is a challenge to consider all effects including the hydrodynamic interactions, the shielding effects, the viscous effects and the wave resonance effect which has been observed in the gaps between the barges and has a significant impact on wave drift forces. In this paper, motion responses and wave drift forces were calculated in frequency domain for both the multi-body system and the single body. Far-field, middle-field and near-field method were all carried out to calculate wave drift forces. Numerical analysis was executed using potential flow code WAMIT. Corresponding model tests were also performed in the Deepwater Offshore Basin in Shanghai Jiao Tong University. Comparison between numerical and experimental results shows that numerical results agree well with the experiment and that middle-field method has better convergence than near-field method. The comparison between the multi-body system and single body shows that the hydrodynamic interactions (including wave shielding effect and Helmholtz resonance of water in the gaps) are remarkable and motion responses in the multi-body system are larger than single barge at some frequencies.

Dual systems for all: Higher-order, role-based relational reasoning as a uniquely derived feature of human cognition

2019 ◽  
Vol 42 ◽  
Author(s):  
Daniel J. Povinelli ◽  
Gabrielle C. Glorioso ◽  
Shannon L. Kuznar ◽  
Mateja Pavlic
Keyword(s):  
Temporal Reasoning ◽  
Higher Order ◽  
Important Case ◽  
Human Cognition ◽  
Relational Reasoning ◽  
Dual Systems ◽  
First Order ◽  
Reasoning System ◽  
Role Based

Abstract Hoerl and McCormack demonstrate that although animals possess a sophisticated temporal updating system, there is no evidence that they also possess a temporal reasoning system. This important case study is directly related to the broader claim that although animals are manifestly capable of first-order (perceptually-based) relational reasoning, they lack the capacity for higher-order, role-based relational reasoning. We argue this distinction applies to all domains of cognition.

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