A Numerical Investigation Into Hydrodynamic Interaction Coefficients for Multiple Freely Floating Bodies in Waves

2021 ◽  
Author(s):  
MIR ALI
Keyword(s):  
Numerical Investigation ◽  
Hydrodynamic Interaction ◽  
Floating Bodies ◽  
Interaction Coefficients

A Numerical Investigation Into Hydrodynamic Interaction Coefficients for Multiple Freely Floating Bodies in Waves

2020 ◽  
Author(s):  
Mir Tareque Ali
Keyword(s):  
Hydrodynamic Interaction ◽  
Three Dimensional ◽  
Computer Code ◽  
Source Distribution ◽  
Hydrodynamic Coefficients ◽  
Body System ◽  
Regular Waves ◽  
Floating Bodies ◽  
Interaction Coefficients ◽  
Multi Body

Abstract When two or more bodies are floating in waves in each other’s vicinity, the fluid loading on the separate bodies will be influenced by the presence of the neighboring bodies. The wave loads on each body are affected, because of sheltering or wave-reflection effects due to the presence of surrounding floating body, while additional loads are exerted by the radiated waves, which are produced by the motions of the neighboring bodies. For a multi-body system, it is important to accurately compute the hydrodynamic coefficients and interaction coefficients, since these parameters will be used later to solve the 6xN simultaneous equations to predict the motion responses (where N is the number of freely floating bodies in the multi-body system). This paper aims to investigate the hydrodynamic interaction coefficients for two three dimensional (3-D) bodies floating freely in each other’s vicinity. Since the nature of hydrodynamic interaction is rather complex, it is usually recommended to study this complicated phenomenon using numerically accurate scheme. A computer code developed using 3-D source distribution method which is based on linear three-dimensional potential theory is used and the validation of the computer code has been justified by comparing the present results with that of the published ones for hydrodynamic coefficients and interaction coefficients of two bodies closely floating in regular waves. The calculated results for box-cylinder model are compared with the published results and the agreement is quite satisfactory. Numerical simulations are further conducted for two closely floating rectangular barges of side-by-side position in regular waves. During the computations of hydrodynamic coefficients and interaction coefficients for multi-body model, the separation distance between the floating bodies have been varied. Finally, some conclusions are drawn on the basis of the present analysis.

A Numerical Investigation on Hydrodynamic Interaction Coefficients for a Group of Truncated Composite Cylinders Floating in Waves

2021 ◽  
Author(s):  
Mir Tareque Ali
Keyword(s):  
Hydrodynamic Interaction ◽  
Three Dimensional ◽  
Computer Code ◽  
Source Distribution ◽  
Floating Body ◽  
Body System ◽  
Floating Bodies ◽  
Interaction Coefficients ◽  
Distribution Method ◽  
Multi Body

Abstract When a group of bodies are floating closely in waves, the fluid loading on these bodies will be influenced due to the presence of the neighboring bodies. The wave loading on each of these bodies are affected, because of the sheltering or wave-reflection effects due to the presence of surrounding floating bodies, while additional loads are exerted by the radiated waves produced by the motions of the nearby floating bodies. For a multiple floating body system, it is important to precisely compute the hydrodynamic interaction coefficients, since these parameters will be used later to solve the 6xN simultaneous equations to predict the motion responses (where N is the number of freely floating bodies in the multi-body system). On the other hand, the hydrodynamic interaction coefficients are absent for an isolated floating body case. This paper investigates the hydrodynamic interaction coefficients for a group of three dimensional (3-D) bodies floating freely in each other’s vicinity. Since the nature of hydrodynamic interaction is rather complex, it is usually recommended to study this complicated phenomenon using numerically accurate scheme. A computer code developed using 3-D source distribution method which is based on linear three-dimensional potential theory is used and the validation of the computer code has been justified by comparing the present results with that of the published ones for the hydrodynamic interaction coefficients of multiple bodies. The agreement between the calculated results with those of the published ones is quite satisfactory. Numerical simulations are further conducted for a group of identical truncated composite circular cylinders floating vertically at close proximity in regular waves. During the computations of hydrodynamic interaction coefficients of this multi-body model for different groups, the number of members in the group as well as the gap width among them has been varied. The paper also examines the occurrence of hydrodynamic resonances in the gap among the floating bodies and the presence of spikes with rapid fluctuation in the results of the diagonal and coupling terms for interaction coefficients. Finally, some conclusions are drawn on the basis of the present analysis.

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.

scholarly journals Impact of Hydrodynamic Interaction Between Pontoons on Global Responses of a Long Floating Bridge Under Wind Waves

2018 ◽  
Author(s):  
Xu Xiang ◽  
Thomas Viuff ◽  
Bernt Leira ◽  
Ole Øiseth
Keyword(s):  
Hydrodynamic Interaction ◽  
Wind Waves ◽  
Vertical Motion ◽  
Interaction Effects ◽  
Viscous Damping ◽  
Interaction Coefficients ◽  
Wave Effects ◽  
Floating Bridge ◽  
Bridge Responses ◽  
The Time Domain

The hydrodynamic interaction between floating bridge pontoons and its impact on the bridge global responses are investigated in the current study. The global model for end-anchored floating bridge for Bjørnefjord crossing is modelled in ORCINA-OrcaFlex. Forty-six pontoons are used to support the bridge, with a centerline distance of 100m between two pontoons. Two models are setup for comparison: (1) The OrcaFlex model with hydrodynamic coefficients of pontoons without hydrodynamic interaction; (2) The OrcaFlex model with hydrodynamic interaction coefficients, which were calculated by ANSYS-AQWA. Firstly, a case study of hydrodynamic interaction effects on added mass, potential damping and diffraction force is given, showing that the piston and sloshing modes have strong correlation with the resonances. Then two sea states were run on the two models with and without hydrodynamic interaction effects. The first order wave effects are included in the analysis. The observed extremes of the time-domain bridge girder bending moments and motions were compared between two models. The comparison shows both reduction and increase of bridge responses depending on the wave directions. A sensitivity test of drag coefficients applied on the pontoon vertical motion is carried out as a rough examination of the neglected viscous damping on the hydrodynamic resonances. The viscous damping effects on the resonances should be further quantified.

Computation of Hydrodynamic Interaction of Multiple Bodies in Waves With a Panel-Free Method

2005 ◽  
Author(s):  
Wei Qiu ◽  
Hongxuan Peng ◽  
Sander M. Calisal ◽  
Jianhong Wang
Keyword(s):  
Hydrodynamic Interaction ◽  
Gaussian Quadrature ◽  
Time Domain Analysis ◽  
Performance Study ◽  
Floating Bodies ◽  
B Splines ◽  
Exciting Forces ◽  
Wave Exciting Forces ◽  
The Green Function ◽  
The Time Domain

The hydrodynamic interaction of multiple floating bodies in waves has been computed in the frequency domain based on the panel-free method developed earlier for the time-domain analysis. The integral equations are first desingularized by removing the singularity in the Green function and then discretized by Gaussian quadrature over the exact geometry. Non-uniform rational B-splines (NURBS) surfaces are employed to represent the exact body surface. Robustness and accuracy of the method has been demonstrated by its application to vertically floating cylinders. Computed motions, hydrodynamic coefficients and wave exciting forces due to interactions are presented and compared with other published results. The numerical method has also been applied to the performance study of a wave energy converter. The computed results were compared with the experimental ones.

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