On Hydrodynamic Interaction Between Several Freely Floating Vertical Cylinders in Waves

2005 ◽  
Author(s):  
Mir Tareque Ali ◽  
Gazi Md. Khalil
Keyword(s):  
Interaction Effect ◽  
Hydrodynamic Interaction ◽  
Computer Code ◽  
Separation Distance ◽  
Numerical Results ◽  
Physical Aspect ◽  
Floating Bodies ◽  
Exciting Forces ◽  
Source Sink ◽  
Vertical Cylinders

This paper investigates the hydrodynamic interaction between several vertical cylinders freely floating in each other’s close vicinity. The physical aspect of hydrodynamic interaction is rather complicated and numerically accurate scheme is highly recommended to study this complex phenomenon. In the present study, 3D source-sink method has been adopted to determine the hydrodynamic coefficients and wave exciting forces by taking into account accurately the effect of hydrodynamic interaction among the different floating bodies. In order to check the convergence of numerical results, mean wetted surface of the floating cylinders are divided into different numbers of rectangular panels. A computer code is developed using 3D source-sink formulations and the validation of the computer code has been justified by comparing the present results with that of the published ones. In order to study the interaction effect, numerical results for a single cylinder have been compared with those of the multi-cylinder ones. The separation distance between the cylinders has been varied to examine the interaction effect for head sea condition. Finally some conclusions have been drawn on the basis of the present analysis.

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.

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.

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.

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.

scholarly journals Wave Exciting Forces on Groups of Floating Bodies

1979 ◽  
Vol 1979 (145) ◽  
pp. 79-87 ◽  
Author(s):  
Akira Masumoto ◽  
Yoshio Yamagami ◽  
Ryuji Sakata
Keyword(s):  
Floating Bodies ◽  
Exciting Forces ◽  
Wave Exciting Forces

Investigations of the Effect of Annulus Taper on Transonic Turbine Cascade Flow

1986 ◽  
Vol 108 (2) ◽  
pp. 285-292 ◽  
Author(s):  
W. Bra¨unling ◽  
F. Lehthaus
Keyword(s):  
Surface Pressure ◽  
Theoretical Calculations ◽  
Three Dimensional ◽  
Computer Code ◽  
Numerical Results ◽  
Test Facility ◽  
Turbine Cascade ◽  
Pressure Distributions ◽  
Aspect Ratios ◽  
Wide Range

In a test facility for rotating annular cascades with three conical test sections of different taper angles (0, 30, 45 deg), experiments are conducted for two geometrically different turbine cascade configurations, a hub section cascade with high deflection and a tip section cascade with low deflection. The evaluation of time-averaged data derived from conventional probe measurements upstream and downstream of the test wheel in the machine-fixed absolute system is based on the assumption of axisymmetric stream surfaces. The cascade characteristics, i.e., mass flow, deflection, and losses, for a wide range of inlet flow angles and outlet Mach numbers are provided in the blade-fixed relative system with respect to the influence of annulus taper. Some of the results are compared with simple theoretical calculations. To obtain some information about the spatial structure of the flow within the cascade passages, surface pressure distributions on the profiles of the rotating test wheels are measured at three different radial blade sections. For some examples those distributions are compared with numerical results on plane cascades of the same sweep and dihedral angles and the same aspect ratios. The computer code used is based on a three-dimensional time-marching finite-volume method solving the Euler equations. Both experimental and numerical results show a fairly good qualitative agreement in the three-dimensional blade surface pressure distributions. This work will be continued with detailed investigations on the spatial flow structure.

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