Hydrodynamic Interaction Forces on Ship Hulls Equipped With Propulsors

2012 ◽  
Author(s):  
Serge Sutulo ◽  
C. Guedes Soares
Keyword(s):  
Pressure Distribution ◽  
Hydrodynamic Interaction ◽  
Potential Interaction ◽  
Interaction Forces ◽  
Ship Hulls ◽  
Actuator Disk ◽  
Close Proximity ◽  
Body Potential ◽  
Yaw Moment ◽  
Accelerating Motion

Typically, study of hydrodynamic interaction between vessels navigating in close proximity to each other is limited to hydrodynamics of bare hulls. Meanwhile, ship propulsors, especially heavily loaded, which may happen in accelerating motion, can alter substantially the flow and distribution of pressure on the hulls which can be viewed as generalization of the thrust deduction phenomenon. The 3D doubled body potential interaction code based on the source panel method developed earlier by the authors has been enhanced to include the effect of a propeller on each of the interacting ships under the assumption that the propeller jets (slipstreams) are not involved into the interaction. Each propeller is simulated by a disk of sinks further approximated with a polygon composed of identical triangular panels with identical constant sink density linked to the thrust of the propulsor according to the actuator disk theory. Comparative computations were carried out for two identical tanker vessels in the close-proximity overtaking manoeuvre at various values of the loading coefficient of each propeller. The loading coefficient is not supposed to be necessarily defined by the steady propulsion point. Numerical results demonstrate that a heavily loaded propeller substantially modifies the pressure distribution on both hulls resulting in alteration of the hydrodynamic interaction loads, especially of the surge force and yaw moment.

Computation of Ship-to-Ship Interaction Forces by a 3D Potential Flow Panel Method in Finite Water Depth

2010 ◽  
Author(s):  
Xueqian Zhou ◽  
Serge Sutulo ◽  
C. Guedes Soares
Keyword(s):  
Water Depth ◽  
Potential Flow ◽  
Hydrodynamic Interaction ◽  
Single Layer ◽  
Mirror Image ◽  
Present Contribution ◽  
Interaction Forces ◽  
Sea Bottom ◽  
Close Proximity ◽  
Finite Water Depth

The double-body 3D potential flow code developed earlier for computing hydrodynamic interaction forces and moments acting on the hulls of the ships sailing in close proximity with neighbouring ships or some other obstacles, is extended to the shallow water case. Two methods for accounting for the finite water depth were implemented: use of truncated mirror image series, and distribution of an additional single layer of sources on parts of the seabed beneath the moving hulls. While the first method does only apply to the flat horizontal seabed, the second one can also deal with the arbitrary bathymetry situations. As appropriate choice of the discretization parameters can significantly affect the accuracy and efficiency of the second method, the present contribution focuses on comparative computations aiming at defining reasonable dimensions of the moving panelled area on the sea bottom and maximum admissible size of the bottom panel. As result, conclusions concerning optimal parameters of the additional set of panels are drawn.

Simulation of the Hydrodynamic Interaction Forces in Close-Proximity Manoeuvring

2008 ◽  
Author(s):  
Serge Sutulo ◽  
C. Guedes Soares
Keyword(s):  
Real Time ◽  
Hydrodynamic Interaction ◽  
Moving Objects ◽  
Time Derivative ◽  
Kirchhoff Equations ◽  
Interaction Forces ◽  
Acceptable Accuracy ◽  
Close Proximity ◽  
Added Masses ◽  
Real Time Simulations

A code for simulating hydrodynamic interaction forces in manoeuvring simulating systems has been created. The algorithm takes into account potential forces only and is based on the Hess and Smith panel method. Own inertial hydrodynamic forces were estimated through pre-calculation of the added masses followed by use of the Thomson–Tait–Kirchhoff equations. Comparative computations of the added masses, surge and sway interaction forces and yaw interaction moments with varying number of surface computational panels showed that on a typical modern PC, an acceptable accuracy in terms of the integrated loads can be reached with a relatively small number of panels permitting real-time simulations with the developed algorithm in the loop. Importance of the account for the local time derivative of the potential has been demonstrated on comparative calculations in simulation of a passing-by manoeuvre. The code can be used for predicting interaction loads with any number of moving objects and fixed obstacles.

Automatic Control of Underway Replenishment Maneuvers in a Random Sea

1978 ◽  
Vol 22 (01) ◽  
pp. 20-28
Author(s):  
Reidar Alvestad
Keyword(s):  
Computer Simulation ◽  
Automatic Control ◽  
Collision Avoidance ◽  
Nonlinear Interaction ◽  
Interaction Forces ◽  
Random Seas ◽  
Close Proximity ◽  
Controller Performance ◽  
Hybrid Computer ◽  
Avoidance Problem

This paper describes a hybrid computer simulation of two ships performing replenishment operations in random seas. Such operations present collision hazards due to the nonlinear interaction forces and moments which result from close proximity maneuvering while underway. Maneuvers are simulated to demonstrate automatic controller performance during station-keeping, station-changing, and the approach and breakaway phases of typical underway replenishment (UNREP) operations. Results indicate that automatic control should be considered as a possible solution to the UNREP collision avoidance problem.

scholarly journals A Fast Algorithm for the Prediction of Ship-Bank Interaction in Shallow Water

2020 ◽  
Vol 8 (11) ◽  
pp. 927
Author(s):  
Jin Huang ◽  
Chen Xu ◽  
Ping Xin ◽  
Xueqian Zhou ◽  
Serge Sutulo ◽  
...  
Keyword(s):  
Shallow Water ◽  
Hydrodynamic Interaction ◽  
Surface Boundary ◽  
Complex Flow ◽  
Ship Maneuvering ◽  
Interaction Forces ◽  
Rankine Source ◽  
Bank Effect ◽  
Sinkage And Trim ◽  
Navigation Safety

The hydrodynamic interaction induced by the complex flow around a ship maneuvering in restricted waters has a significant influence on navigation safety. In particular, when a ship moves in the vicinity of a bank, the hydrodynamic interaction forces caused by the bank effect can significantly affect the ship’s maneuverability. An efficient algorithm integrated in onboard systems or simulators for capturing the bank effect with fair accuracy would benefit navigation safety. In this study, an algorithm based on the potential-flow theory is presented for efficient calculation of ship-bank hydrodynamic interaction forces. Under the low Froude number assumption, the free surface boundary condition is approximated using the double-body model. A layer of sources is dynamically distributed on part of the seabed and bank in the vicinity of the ship to model the boundary conditions. The sinkage and trim are iteratively solved via hydrostatic balance, and the importance of including sinkage and trim is investigated. To validate the numerical method, a series of simulations with various configurations are carried out, and the results are compared with experiment and numerical results obtained with RANSE-based and Rankine source methods. The comparison and analysis show the accuracy of the method proposed in this paper satisfactory except for extreme shallow water cases.

Maneuvering Simulation of Two Ships During Meeting and Passing

2014 ◽  
Vol 69 (7) ◽  
Author(s):  
Koki Kitagawa ◽  
Masaaki Sano ◽  
Hironori Yasukawa
Keyword(s):  
Water Depth ◽  
Panel Method ◽  
Time Step ◽  
Interaction Forces ◽  
Motion Equations ◽  
Close Proximity ◽  
External Forces ◽  
Ship Speed

Motion equations of two ships maneuvering in close proximity are solved in consideration of the interaction between hulls. The interaction forces are calculated by a 3D panel method as a function of the ship position in the time step and considered as external forces in maneuvering. Four kinds of ships are prepared and the maneuvering motions are simulated with variation of the combination of ships, water depth, ship speed and draft. The effect of those parameters on the interaction forces and two ships behaviors are investigated. 

Vertical Relative Motion Between Two Adjacent Platforms in Oblique Waves

1985 ◽  
Vol 107 (4) ◽  
pp. 455-460 ◽  
Author(s):  
C. H. Kim ◽  
M. C. Fang
Keyword(s):  
Relative Motion ◽  
Hydrodynamic Interaction ◽  
Two Dimensional ◽  
Oblique Waves ◽  
Strip Method ◽  
Strip Theory ◽  
Close Proximity ◽  
Relative Motions

The paper presents a strip theory and its correlation with experiment and analysis on the relative motions of two ships. The ships are in close proximity and in parallel position in oblique waves. The two-dimensional procedure takes account of the hydrodynamic interaction between two cylindrical bodies. It was found that the strip method is a useful technique to predict the hydrodynamically coupled motions of two ships.

Experimental Investigation of Ice Mass Hydrodynamic Interaction With Offshore Structure in Close Proximity

2015 ◽  
Author(s):  
Tanvir Mehedi Sayeed ◽  
Bruce Colbourne ◽  
Heather Peng ◽  
Benjamin Colbourne ◽  
Don Spencer
Keyword(s):  
Hydrodynamic Interaction ◽  
Impact Load ◽  
Numerical Study ◽  
Numerical Models ◽  
Offshore Structures ◽  
Ocean Engineering ◽  
Offshore Structure ◽  
Area Of Interest ◽  
Close Proximity ◽  
The Impact

Iceberg/bergy bit impact load with fixed and floating offshore structures and supply ships is an important design consideration in ice-prone regions. Studies tend to divide the iceberg impact problem into phases from far field to contact. This results in a tendency to over simplify the final crucial stage where the structure is impacted. The authors have identified knowledge gaps and their influence on the analysis and prediction of iceberg impact velocities and loads (Sayeed et. al (2014)). The experimental and numerical study of viscous dominated very near field region is the main area of interest. This paper reports preliminary results of physical model tests conducted at Ocean Engineering Research Center (OERC) to investigate hydrodynamic interaction between ice masses and fixed offshore structure in close proximity. The objective was to perform a systematic study from simple to complex phenomena which will be a support base for the development of subsequent numerical models. The results demonstrated that hydrodynamic proximity and wave reflection effects do significantly influence the impact velocities at which ice masses approach to large structures. The effect is more pronounced for smaller ice masses.

Transient Analysis of Hydrodynamic Interaction Effects on an Autonomous Underwater Vehicle in Proximity of a Moving Submarine

2015 ◽  
Vol 157 (A4) ◽  
pp. 205-218
Keyword(s):  
Relative Motion ◽  
Transient Analysis ◽  
Hydrodynamic Interaction ◽  
Autonomous Underwater Vehicle ◽  
Underwater Vehicle ◽  
Cfd Simulations ◽  
Close Proximity ◽  
Computational Fluid Dynamics Cfd ◽  
Submarine Hull ◽  
Hull Forms

"When an Autonomous Underwater Vehicle (AUV) is operating close to a moving submarine, the hydrodynamic interaction between the two vehicles can prevent the AUV from maintaining its desired trajectory. This can lead to mission failure and, in extreme cases, collision with the submarine. This paper outlines the transient interaction influence on the hydrodynamic coefficients of an AUV operating in close proximity and in relative motion to a larger moving submarine. The effects of relative motion on the interaction behaviour were investigated via two manoeuvres, i.e. the AUV overtaking and being overtaken by the submarine at different relative forward velocities and lateral distances. The results presented are from a series of Computational Fluid Dynamics (CFD) simulations on axisymmetric AUV and submarine hull forms, with validation of the CFD model carried out through scaled captive model experiments. The results showed that an AUV becomes less susceptible to the interaction influence when overtaking at speeds higher than the submarine. The implications of the interaction influence on the AUV’s ability to safely manoeuvre around the submarine are also discussed."

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