Computation of ship hydrodynamic interaction forces in restricted waters using potential theory

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.

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

Volume 7B: Ocean Engineering ◽

10.1115/omae2019-96151 ◽

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.

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CFD Analysis of Ship-to-Ship Hydrodynamic Interaction

Journal of Marine Science and Application ◽

10.1007/s11804-018-0010-z ◽

2018 ◽

Vol 17 (1) ◽

pp. 21-37 ◽

Cited By ~ 3

Author(s):

A. D. Wnęk ◽

Serge Sutulo ◽

C. Guedes Soares

Keyword(s):

Hydrodynamic Interaction ◽

Cfd Analysis ◽

Ship Hydrodynamic

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

Journal of Marine Science and Engineering ◽

10.3390/jmse8110927 ◽

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.

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Hydrodynamic Interaction Forces on Ship Hulls Equipped With Propulsors

Volume 4: Offshore Geotechnics; Ronald W. Yeung Honoring Symposium on Offshore and Ship Hydrodynamics ◽

10.1115/omae2012-84181 ◽

2012 ◽

Cited By ~ 1

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.

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

29th International Conference on Ocean, Offshore and Arctic Engineering: Volume 4 ◽

10.1115/omae2010-20497 ◽

2010 ◽

Cited By ~ 3

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.

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