Virtual Testbed: Simulation of Air Flow Around Ship Hull and Its Effect on Ship Motions

Virtual Testbed: Simulation of Ocean Wave Reflection from the Ship Hull

Computational Science and Its Applications – ICCSA 2020 - Lecture Notes in Computer Science ◽

10.1007/978-3-030-58817-5_3 ◽

2020 ◽

pp. 29-39

Author(s):

Ivan Petriakov ◽

Alexander Degtyarev ◽

Denis Egorov ◽

Ivan Gankevich ◽

Anton Gavrikov ◽

...

Keyword(s):

Wave Reflection ◽

Ship Hull ◽

Ocean Wave ◽

Virtual Testbed

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Safety Assessment of Ship Launching Based on Airbags With the Nonlinear Rigidity of Airbags Being Considered

Volume 2: Structures, Safety and Reliability ◽

10.1115/omae2009-79149 ◽

2009 ◽

Author(s):

Huilong Ren ◽

Chenfeng Li ◽

Guoqing Feng ◽

Xiaobo Liu ◽

Jian Zhang

Keyword(s):

Calculation Method ◽

Scientific Method ◽

Safety Assessment ◽

Ship Hull ◽

Ship Motions ◽

Equilibrium Conditions ◽

Air Bags ◽

Hull Structure ◽

Comparison Of The Results ◽

Force Equilibrium

Launching based on airbags is an important method of ship launching. However, there has not a scientific method for quantitative assessment on the strength of hull structure and safety of airbags at present. With the increases of tonnage of ships launching on airbags, this problem becomes increasingly apparent and important. With the nonlinear rigidity of air-bags and force equilibrium conditions of ship-hull beam being considered during launching, a method based on full ship FEA was put forward to assess the strength of ship structure and the safety of airbags in this paper. The main contents are as follows: Considering nonlinear rigidity of airbags, a calculation method of rigidity of airbags was studied; Based on the elastic launching calculation, a method of calculating ship motion and force on ship hull was studied with the nonlinear rigidity of elastic foundation being considered; Based on the above condition of ship motions and forces, the stress of hull structure and the force on airbags are calculated by full ship FEA; The safety of a real ship launching based on airbags was assessed, based on the comparison of the results with references, the safety of ship launching by airbags and the reliability of the calculation method in this paper are verified.

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A Method of Immersed Surface Capture for Broaching Application

Volume 5: Ocean Engineering ◽

10.1115/omae2013-11527 ◽

2013 ◽

Cited By ~ 1

Author(s):

Boris Horel ◽

Pierre-Emmanuel Guillerm ◽

Jean-Marc Rousset ◽

Bertrand Alessandrini

Keyword(s):

Free Surface ◽

External Disturbance ◽

Static Stability ◽

Mechanical Action ◽

Ship Hull ◽

Ship Motions ◽

Time Step ◽

Following Seas ◽

Intact Stability ◽

Ship Behavior

The modeling of ship behavior in astern seas requires a large range of maneuverability and seakeeping knowledge since the understanding of the ship motions returns to solve a fluid structure interactions problem between waves and the ship hull. The broaching phenomenon is known as an abrupt change in motion in the horizontal plane, resulting in a loss of ship’s heading. It is characterized by a sudden divergence of yaw. Thus, there is a transfer of the kinetic energy on the roll axis that increases the risk of ship capsize. In the aim of modeling this phenomenon, the developed model uses the capture of the intersection between the ship hull and the free surface. Thus, we can overcome the hydrostatic stiffness matrix and integrate directly the hydrostatic pressure on the immersed surface. This method has the advantage of taking into account non-linearities of the wave profile into the calculation of the immersed surface, directly by performing a remodeling of the facets near the free surface. In the literature, three main factors are likely to affect the stability: the loading of the vessel, the presence of external disturbance torques and inadequate conditions of navigation, as is the case when a ship is caught in a storm. The first two factors are taken into account in the study of static stability, while the third factor is considered in the study of the instantaneous stability. Hydrostatic behavior of a ship is interesting when one wants to know her intact stability limits in calm seas. However, in the study of the ship behavior in following seas, the ship is no longer in usual conditions of navigation, but in unsuitable conditions requiring the study of the instantaneous stability. In the model formulation, the dynamic torsor comes from the general non-linear maneuverability equations and the time advance is solved by a 4th order Runge Kutta scheme with a constant time step. The torsor of the total applied mechanical action on the ship hull is expressed as the superposition of six torsors (gravity, hydrostatic, Froude Krylov, radiation, hydrodynamics and maneuverability) expressed in the center of gravity of the ship. Thus, we obtain a strong coupling between the maneuverability and seakeeping equations. Validation cases will be conducted and presented. The improvement of the model will require the implementation of test campaigns that will be specific for the study of ship behavior in astern seas. Validation of the model will help to define new stability criteria for ships in wave.

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