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.

A Numerical Method for Calculation of Ship–Ship Hydrodynamics Interaction in Shallow Water Accounting for Sinkage and Trim

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Huilong Ren ◽  
Chen Xu ◽  
Xueqian Zhou ◽  
Serge Sutulo ◽  
Carlos Guedes Soares
Keyword(s):  
Shallow Water ◽  
Hydrodynamic Interaction ◽  
Mirror Image ◽  
Image Method ◽  
Interaction Forces ◽  
Ship Hydrodynamics ◽  
Time Simulation ◽  
Water Accounting ◽  
Ship Hydrodynamic ◽  
Sinkage And Trim

Abstract Sinkage and trim, which often occur to ships moving in shallow water, do not only have an effect on the ship–ship hydrodynamic interaction forces but also increase the risk of grounding. Potential flow-based online calculation of ship–ship hydrodynamic interaction forces without accounting for dynamic sinkage and trim is able to capture the hydrodynamic interaction effects with fair accuracy; however, there are still discrepancies in many cases, especially in the case of shallow water. An algorithm based on the potential theory has been devised for real-time simulation of the hydrodynamic interaction between two ships in shallow water accounting for sinkage and trim. The shallow water condition is modeled using the mirror image method. The sinkage and trim are solved iteratively based on the principle of hydrodynamic balance, where a mesh trimming procedure is carried out when the waterline is changed. Simulations are performed with and without accounting for the sinkage and trim, and comparison with experimental results shows a fair agreement.

A Numerical Method for Calculation of Ship-Ship Hydrodynamics Interaction in Shallow Water Accounting for Sinkage and Trim

2019 ◽  
Author(s):  
Huilong Ren ◽  
Chen Xu ◽  
Xueqian Zhou ◽  
Serge Sutulo ◽  
Carlos Guedes Soares
Keyword(s):  
Shallow Water ◽  
Hydrodynamic Interaction ◽  
Mirror Image ◽  
Image Method ◽  
Interaction Forces ◽  
Time Simulation ◽  
Water Accounting ◽  
Ship Hydrodynamic ◽  
Sinkage And Trim ◽  
Hydrostatic Balance

Abstract Sinkage and trim, which often occur to ships moving in shallow water, do not only have an effect on the ship-ship hydrodynamic interaction forces, but also increase the risk of grounding. An algorithm based on the potential theory has been devised for real-time simulation of the hydrodynamic interaction between two ships in shallow water accounting for sinkage and trim. The shallow water condition is modeled using the mirror image method; while the sinkage and trim are solved iteratively based on the principle of hydrostatic balance, where a mesh trimming procedure is performed when the waterline is changed. Simulations are performed with and without accounting for the sinkage and trim, and comparison with experimental results shows a fair agreement.

scholarly journals Ship-to-Ship Interaction during Overtaking Operation in Shallow Water

2015 ◽  
Vol 59 (03) ◽  
pp. 172-187
Author(s):  
Zhi-Ming Yuan ◽  
Paula Kellet ◽  
Atilla Incecik ◽  
Osman Turan ◽  
Evangelos Boulougouris
Keyword(s):  
Shallow Water ◽  
Hydrodynamic Interaction ◽  
Contributory Factor ◽  
Test Results ◽  
Loss Of Life ◽  
Narrow Channels ◽  
Rankine Source ◽  
Wave Patterns ◽  
Computational Fluid Dynamics Cfd ◽  
Numerical Program

Hydrodynamic interaction continues to be a major contributory factor in marine casualties and hazardous incidents, in particular, in the case of overtaking operations. The situation becomes even worse when the overtaking operation occurs in shallow and narrow channels, where the interaction can cause the vessels to collide and, in one case has caused the capsizal of the smaller vessel with loss of life. The aim of this article is to propose a methodology, as well as to discuss the development of a numerical program, to predict the ship-to-ship interaction during overtaking operations in shallow water. Since the vessels involved in this study have different forward speeds, an uncoupled method will be used to solve the boundary value problem. The in-house multibody hydrodynamic interaction program MHydro, which is based on the 3D Rankine source method, is used and extended here to investigate the interactive forces and wave patterns between two ships during an overtaking operation. The calculations given in this article are compared with model test results as well as published computational fluid dynamics (CFD) calculations. Very satisfactory agreement has been obtained, which indicates that the proposed methodology and developed program are successfully validated to predict the hydrodynamic interaction between two ships advancing in confined waters. The discussions also highlight the speed effects.

Hydrodynamic Interaction Between Two Ships Arranged Side by Side in Shallow Water

2014 ◽  
Author(s):  
Zhiming Yuan ◽  
Atilla Incecik ◽  
Shi He
Keyword(s):  
Shallow Water ◽  
Hydrodynamic Interaction ◽  
Wave Pattern ◽  
Present Calculation ◽  
Water Effect ◽  
Green Function Method ◽  
Rankine Source ◽  
The Mean ◽  
Shallow Water Effect ◽  
Good Agreement

The hydrodynamic interaction between two ships with side-by-side arrangement is analyzed by using 3-D Rankine source panel code. The source points are distributed over the mean wetted body surface as well as on the free surface. The shallow water effect has been taken into consideration. Moreover, the influence of the distance between the vessels is also investigated. To verify the present code, two Wigley III hulls are simulated both in beam sea and head sea conditions. The wave pattern and the motion RAOs of 6-DOF are calculated by present code and compared with WADAM program which is based on Green function method. From the comparisons, good agreement is found between present calculation and Wadam results. It is found that the hydrodynamic interactions are generally important especially in beam sea case. The resonant frequency is greatly influenced by the distance between the vessels.

New Generic Equation for Interaction Effects on a Moored Containership Due to a Passing Tanker

2006 ◽  
Vol 50 (03) ◽  
pp. 278-287 ◽  
Author(s):  
K. S. Varyani ◽  
M. Vantorre
Keyword(s):  
Horizontal Plane ◽  
Hydrodynamic Interaction ◽  
Equations Of Motion ◽  
Test Program ◽  
Ship Maneuvering ◽  
Interaction Forces ◽  
Captive Model Test ◽  
The Mathematical Model ◽  
Generic Equation ◽  
Systematic Database

In order to improve the formulation of moored-passing ship interaction forces and moments in the mathematical model of a ship maneuvering simulator, a comprehensive captive model test program was carried out and a theoretical calculation method was developed. At present, semiempirical approaches, resulting in an estimation of forces and moments in the horizontal plane caused by hydrodynamic interaction on a moored ship due to a passing ship, are not available in literature. The present research intends to enhance the theoretical approach by validating the calculated peak forces and moments with experimental data. The numerical method is subsequently applied to generate a systematic database for the development of a new set of generic formulae for estimating the effect of passing vessels on moored ships in the equations of motion for surge, sway, and yaw applied in maneuvering and moor-ing simulators.

Investigation of Sinkage and Trim by Ships in Shallow Water Based on Overset Grid

2015 ◽  
Vol 713-715 ◽  
pp. 2126-2132
Author(s):  
Da Ming Sun ◽  
Ji Yong Liu ◽  
Qing Wen Kong
Keyword(s):  
Shallow Water ◽  
Equations Of Motion ◽  
Navier Stokes ◽  
Overset Grid ◽  
Ship Hulls ◽  
Surface Ship ◽  
Solving Equations ◽  
Sinkage And Trim ◽  
Volume Method ◽  
Good Agreement

A study on the navigation behavior for ships in shallow water had been carried out on CFD. The problem of surface ship hulls free of sinkage and trim in shallow water is analyzed numerically by simultaneously solving equations of the Reynolds averaged Navier-Stokes (RANS). The computations, based on the single-phase level set and overset grid, are discretized by finite volume method (FVM). An earth-based reference system is used for the solution to the fluid flow, while a ship-based reference is used to compute the rigid-body equations of motion. A S60 CB=0.6 ship model is taken as an example to the numerical simulation. Numerical results of the sinkage and trim of the seven Froude Numbers (Fn=0.5~0.8) are compared against experimental data, which have a good agreement.

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.

URANS Simulation of an Appended Hull During Steady Turn With Propeller Represented by an Actuator Disk Model

2011 ◽  
Author(s):  
Charles M. Dai ◽  
Ronald W. Miller
Keyword(s):  
Flow Field ◽  
Cross Flow ◽  
Field Measurements ◽  
Navier Stokes ◽  
Experimental Measurements ◽  
Complex Flow ◽  
Ship Maneuvering ◽  
Disk Model ◽  
Actuator Disk ◽  
Propeller Wake

This paper reports on the comparison between computational simulations and experimental measurements of a surface vessel in steady turning conditions. The primary purpose of these efforts is to support the development of physics-based high fidelity maneuvering simulation tools by providing accurate and reliable hydrodynamic data with relevance to maneuvering performances. Reynolds Averaged Unsteady Navier Stokes Solver (URANS): CFDSHIPIOWA was used to perform simulations for validation purposes and for better understanding of the fundamental flow physics of a hull under maneuvering conditions. The Propeller effects were simulated using the actuator disk model included in CFDShip-Iowa. The actuator disk model prescribes a circumferential averaged body force with axial and tangential components. No propeller generated side forces are accounted for in the model. This paper examines the effects of actuator disk model on the overall fidelity of a RANS based ship maneuvering simulations. Both experiments and simulations provide physical insights into the complex flow interactions between the hull and various appendages, the rudders and the propellers. The experimental effort consists of flow field measurements using Stereo Particle-Image Velocimetry (SPIV) in the stern region of the model and force and moment measurements on the whole ship and on ship components such as the bilge keels, the rudders, and the propellers. Comparisons between simulations and experimental measurements were made for velocity distributions at different transverse planes along the ship axis and different forces components for hull, appendages and rudders. The actuator disk model does not predict any propeller generated side forces in the code and they need to be taken into account when comparing hull and appendages generated side forces in the simulations. The simulations were compared with experimental results and they both demonstrate the cross flow effect on the transverse forces and the propeller slip streams generated by the propellers during steady turning conditions. The hull forces (include hull, bilge keels, skeg, shafting and strut) predictions were better for large turning circle case as compared with smaller turning circle. Despite flow field simulations appear to capture gross flow features qualitatively; detailed examinations of flow distributions reveal discrepancies in predictions of propeller wake locations and secondary flow structures. The qualitative comparisons for the rudders forces also reveal large discrepancies and it was shown that the primary cause of discrepancies is due to poor predictions of velocity inflow at the rudder plane.

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