Numerical simulations of wave-induced ship motions in regular oblique waves by a time domain panel method

2010 ◽  
Vol 22 (S1) ◽  
pp. 408-415 ◽  
Author(s):  
Jing-pu Chen ◽  
De-xiang Zhu
Keyword(s):  
Numerical Simulations ◽  
Time Domain ◽  
Panel Method ◽  
Ship Motions ◽  
Oblique Waves ◽  
Wave Induced

Motion Prediction of the Ship With Sloshing Tanks

2009 ◽  
Author(s):  
Kang Zou ◽  
Quan-ming Miao ◽  
Ren-qing Zhu
Keyword(s):  
Time Domain ◽  
Three Dimensional ◽  
Panel Method ◽  
Ship Motion ◽  
Motion Prediction ◽  
Ship Motions ◽  
Motion Responses ◽  
Motion Problem ◽  
Good Agreement

Sloshing flow in ship tanks is excited by ship motions, but it affects the ship motions in reverse. This paper focuses on the motion responses of the ship in waves with consideration of coupled effects with sloshing in tanks. A three-dimensional panel method in time-domain is applied to solve the ship motion problem, and the sloshing tanks are solved by commercial CFD software simultaneously. Experiments were carried out on a SL175 ship and good agreement is obtained.

An Investigation Into the Limitations of the Panel Method and the Gap Effect for a Fixed and a Floating Structure Subject to Waves

2016 ◽  
Author(s):  
Blanca Peña ◽  
Aaron McDougall
Keyword(s):  
Time Domain ◽  
Real Life ◽  
Added Mass ◽  
Panel Method ◽  
Gap Effect ◽  
Wave Radiation ◽  
Literature Study ◽  
Floating Structure ◽  
Cfd Analyses ◽  
Wave Induced

The wave-induced motions of vessels moored next to a fixed object and open to the sea impact the operability of many offshore operations, and should be assessed in order to avoid accidents and catastrophes. When analysing vessels moored by a fixed object (e.g. quay-side or platform), time domain simulations have shown numeric instabilities resulting in unreliable outcomes. The origin of the numerical instability might lie in the hydrodynamic added mass and wave radiation damping. This is typically calculated using potential flow methods and influenced by the existence of standing waves in the gap between the two bodies. For certain frequencies, these give negative values, potentially causing instabilities in non-linear (coupled) time domain simulations. In these cases, the vessel can behave unexpectedly, generating energy rather than dissipating it. As such, certain simulations have been disregarded as they are unlikely to accurately represent real-life scenarios. This paper investigates and compares added mass and damping using two different tools and studies the gap effect when conducting diffraction analysis using 3D panel methods. The work covers a literature study into potential theory, multibody analysis, Computational Fluid Dynamics (CFD) and lid techniques. This is followed by a study conducted using both panel method and CFD analyses. The results from both approaches have been compared, showing interesting information and the necessity of researching more into the problem addressed in this paper.

Time Domain Simulation of the Maneuvering of a Vessel in a Seaway

2009 ◽  
Author(s):  
Elin Marita Hermundstad ◽  
Jan R. Hoff
Keyword(s):  
Time Domain ◽  
Transfer Functions ◽  
Experimental Results ◽  
Numerical Code ◽  
Ship Motions ◽  
Time Domain Simulation ◽  
Regular Waves ◽  
Simulation Code ◽  
Wigley Hull ◽  
Wave Induced

This paper presents a new unified seakeeping-maneuvering simulation model valid for surface ships and underwater vessels. If the total ship motions are derived from the traditional formulations for the hydrodynamic and maneuvering models, considering them as two separate problems, the results will be inconsistent. It has therefore been necessary to develop a unified formulation which calculates the total ship motions including both the maneuvering aspects and the wave induced motions. Focus in this study has been on submarines. Examples of application of the developed time domain simulation code are given. These are simulations of the response and corresponding control plane forces of a submarine in straight line motions in regular waves at given headings. The developed code can also be used to e.g. simulate turning circles. This has been conducted for the same submarine, and the results are compared to experimental results. Additionally, simulations of the response of a surface vessel (Wigley hull) with forward speed in regular waves at given headings are presented. In this case only the potential forces are considered. The results from the simulations are used to establish motion transfer functions, which are compared to other numerical and experimental results. There are some limitations in the developed method which affects the application area of the numerical code. This refers particularly to underwater vessels. This will be addressed, and further possible development of the method will be discussed.

Improvement of Rankine Panel Method for Seakeeping Prediction of a Ship in Low Frequency Region

2016 ◽  
Author(s):  
Eiji Yasuda ◽  
Hidetsugu Iwashita ◽  
Masashi Kashiwagi
Keyword(s):  
Low Frequency ◽  
Radiation Condition ◽  
Panel Method ◽  
Ship Motions ◽  
Surface Boundary ◽  
Low Frequencies ◽  
Computational Region ◽  
Rankine Panel Method ◽  
Free Surface Boundary Condition ◽  
Wave Induced

Rankine panel methods have been studied for solving 3D seakeeping problems of a ship with forward speed and oscillatory motions. Nevertheless, there is a drawback in the numerical method for satisfying the radiation condition of outgoing waves at low frequencies, because the waves generated ahead of a ship reflect from the outward computational boundary and smear the flow around the ship. The so-called panel shift technique has been adopted in the frequency-domain Rankine panel method, which is effective when the generated waves propagate downstream of a ship. In this paper, in addition to this conventional panel shift method, Rayleigh’s artificial friction is introduced in the free-surface boundary condition to suppress longer wave components in a computational region apart from the ship. With this practical new method, it is shown that there is no prominent wave reflection from the side and/or upstream computational boundaries even in the range of low frequencies. As a consequence, the unsteady pressure, hydrodynamic forces, wave-induced ship motions, added resistance are computed with reasonable accuracy even in following waves and in good agreement with measured results in the experiment using a bulk carrier model which is also conducted for the present study.

Prediction of Ship Response Statistics in Extreme Seas Using Model Test Data and Numerical Simulations Based on the Rankine Panel Method

2013 ◽  
Author(s):  
Bingjie Guo ◽  
Elzbieta M. Bitner-Gregersen ◽  
Hui Sun ◽  
Jens Bloch Helmers
Keyword(s):  
Numerical Simulations ◽  
Linear Codes ◽  
Bending Moment ◽  
Rogue Waves ◽  
Model Tests ◽  
Panel Method ◽  
Irregular Waves ◽  
Ship Motions ◽  
University Of Berlin ◽  
Non Linear

Earlier investigations have indicated that proper prediction of non-linear response due to non-linear waves is important for ship safety in extreme seas. Nonlinearities may increase significantly ship response in steep sea-states. The topic has not been sufficiently investigated yet, particularly when rogue waves are considered. A question remains whether the existing linear codes can predict nonlinear responses with a satisfactory accuracy and how large the deviations from linear predictions are. To indicate it, response statistics have been studied based on the model tests carried out in the Spanish basin CEHIPAR and the sea-keeping tank of the Technical University of Berlin (TUB), and compared with the results derived from numerical simulations using the DNV code WASIM. It is a potential code for wave-ship interaction based on 3D Panel method, which can perform both linear and nonlinear simulations. The numerical simulations with WASIM and the model tests including extreme and rogue waves have been performed on 3 different ship types: Chemical tanker, LNG tanker and a Cruise ship. The analysis includes both regular and irregular waves. Ship motions and bending moments have been studied. The effect of water depth on ship responses is also investigated. The study indicates that nonlinearities may have significant impact on extreme motions and bending moment induced by strongly nonlinear waves. Uncertainties related to the results are also discussed.

Rankine source time domain method for nonlinear ship motions in steep oblique waves

2018 ◽  
Vol 14 (3) ◽  
pp. 295-308 ◽  
Author(s):  
Malte Riesner ◽  
Guillermo Chillcce ◽  
Ould el Moctar
Keyword(s):  
Time Domain ◽  
Time Domain Method ◽  
Ship Motions ◽  
Oblique Waves ◽  
Rankine Source ◽  
Domain Method

scholarly journals RANS Prediction of Wave-Induced Ship Motions, and Steady Wave Forces and Moments in Regular Waves

2021 ◽  
Vol 9 (12) ◽  
pp. 1459
Author(s):  
Qingze Gao ◽  
Lifei Song ◽  
Jianxi Yao
Keyword(s):  
Wave Amplitude ◽  
Ship Motions ◽  
Wave Forces ◽  
Inertial Effects ◽  
Added Resistance ◽  
Oblique Waves ◽  
Steady Wave ◽  
Head Waves ◽  
Wave Induced ◽  
Hydrodynamic Effects

The wave-induced motions, and steady wave forces and moments for the oil tanker KVLCC2 in regular head and oblique waves are numerically predicted by using the expanded RANS solver based on OpenFOAM. New modules of wave boundary condition are programed into OpenFOAM for this purpose. In the present consideration, the steady wave forces and moments include not only the contribution of hydrodynamic effects but also the contribution of the inertial effects due to wave-induced ship motions. The computed results show that the contribution of the inertial effects due to heave and pitch in head waves is non-negligible when wave-induced motions are of large amplitude, for example, in long waves. The influence of wave amplitude on added resistance in head waves is also analyzed. The dimensionless added resistance becomes smaller with the increasing wave amplitude, indicating that added resistance is not proportional to the square of wave amplitude. However, wave amplitude seems not to affect the heave and pitch RAOs significantly. The steady wave surge force, sway force and yaw moment for the KVLCC2 with zero speed in oblique waves are computed as well. The present RANS results are compared with available experimental data, and very good agreements are found between them.

Prediction of Ship Motions Via a Three-Dimensional Time-Domain Method Following a Quad-Tree Adaptive Mesh Technique

2020 ◽  
Vol 27 (1) ◽  
pp. 29-38
Author(s):  
Teng Zhang ◽  
Junsheng Ren ◽  
Lu Liu
Keyword(s):  
Free Surface ◽  
Incident Wave ◽  
Time Domain ◽  
Three Dimensional ◽  
Adaptive Mesh ◽  
Wave Profile ◽  
Time Domain Method ◽  
Ship Motions ◽  
Quad Tree ◽  
Mesh Technique

AbstractA three-dimensional (3D) time-domain method is developed to predict ship motions in waves. To evaluate the Froude-Krylov (F-K) forces and hydrostatic forces under the instantaneous incident wave profile, an adaptive mesh technique based on a quad-tree subdivision is adopted to generate instantaneous wet meshes for ship. For quadrilateral panels under both mean free surface and instantaneous incident wave profiles, Froude-Krylov forces and hydrostatic forces are computed by analytical exact pressure integration expressions, allowing for considerably coarse meshes without loss of accuracy. And for quadrilateral panels interacting with the wave profile, F-K and hydrostatic forces are evaluated following a quad-tree subdivision. The transient free surface Green function (TFSGF) is essential to evaluate radiation and diffraction forces based on linear theory. To reduce the numerical error due to unclear partition, a precise integration method is applied to solve the TFSGF in the partition computation time domain. Computations are carried out for a Wigley hull form and S175 container ship, and the results show good agreement with both experimental results and published results.

Sign in / Sign up

Export Citation Format

Share Document