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 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.

SHIP-SHIP HYDRODYNAMIC INTERACTION IN CONFINED WATERS WITH COMPLEX BOUNDARIES BY A PANELLED MOVING PATCH METHOD

2021 ◽  
Vol 158 (A1) ◽  
Author(s):  
X-Q Zhou ◽  
S Sutulo ◽  
C Guedes Soares
Keyword(s):  
Shallow Water ◽  
Satisfactory Agreement ◽  
Potential Flow ◽  
Hydrodynamic Interaction ◽  
Mirror Image ◽  
Ship Hulls ◽  
Seabed Topography ◽  
Image Technique ◽  
Ship Hydrodynamic ◽  
Complex Boundaries

This paper presents a potential flow solution for online estimation of hydrodynamic interaction between ships moving in restricted waters with complex boundaries. Each ship in concern is linked with a moving patch representing the arbitrary bathymetry beneath it. The wetted surfaces of ship hulls are meshed and loaded prior to the simulation, while the moving patches are dynamically discretized by a fast and robust mesh generator. The proposed method is validated for the ship- ship interaction case in the shallow water case with a flat and horizontal seabed where the mirror image technique is applicable, and satisfactory agreement is obtained. The method is further applied to simulate two interaction scenarios involving arbitrary seabed topography, and the numerical results are obtained and discussed.

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.

Bank effects on ship–ship hydrodynamic interaction in shallow water based on high-order panel method

2017 ◽  
Vol 12 (6) ◽  
pp. 843-861 ◽  
Author(s):  
Hua-fu Xu ◽  
Zao-jian Zou ◽  
Si-wei Wu ◽  
Xiao-yan Liu ◽  
Lu Zou
Keyword(s):  
Shallow Water ◽  
Hydrodynamic Interaction ◽  
High Order ◽  
Panel Method ◽  
Water Based ◽  
Ship Hydrodynamic ◽  
Bank Effects

ShallowFlow: A Program to Model Ship Hydrodynamics in Shallow Water

2014 ◽  
Author(s):  
Tim P. Gourlay
Keyword(s):  
Shallow Water ◽  
Cross Section ◽  
Hydrodynamic Pressure ◽  
Open Water ◽  
Arbitrary Cross Section ◽  
Far Field ◽  
Shallow Water Theory ◽  
Ship Hydrodynamics ◽  
Cruise Ships ◽  
Sinkage And Trim

In this article we present details of “ShallowFlow”, a computer program to model the hydrodynamic flow around ships in calm shallow water. The program is based on slender-body shallow-water theory. Outputs from the program include far-field hydrodynamic pressure and flow velocities; free surface drawdown; sinkage and trim. Varying transverse bathymetry including open water, dredged channels, and canals of arbitrary cross-section may be modelled. The method is best suited to displacement ships, including cargo ships, ferries, cruise ships, warships and superyachts.

Combination Resonance of a Magnet Over a High-TC Superconductor Excited Vertically

2001 ◽  
Author(s):  
Toshihiko Sugiura ◽  
Masayuki Kondo
Keyword(s):  
Magnetic Force ◽  
Vertical Direction ◽  
Vertical Motion ◽  
Mirror Image ◽  
Image Method ◽  
Combination Resonance ◽  
Nonlinear Functions ◽  
High Tc ◽  
High Tc Superconductor ◽  
Oscillation Modes

Abstract This research deals with nonlinear dynamics of a permanent magnet freely levitated above a high-Tc superconductor (HTSC) excited in the vertical direction. Magnetic force and torque can be evaluated analytically by the advanced mirror image method as nonlinear functions of both displacement and roll angle of the magnet. Equations of 3 d.o.f. motion show that the magnet has two oscillation modes due to linear coupling of the horizontal and roll motions. The both modes can be excited by nonlinear coupling with vertical motion when the superconductor is exited vertically in the neighborhood of the sum of the natural frequency of each mode. Frequency response of this combination resonance was numerically simulated. This resonance was also observed in experiments.

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