Study on the Parametric Rolling of Medium-Sized Containership Based on Nonlinear Time Domain Analysis

2020 ◽  
Author(s):  
Seung Ho Yang
Keyword(s):  
Mathematical Model ◽  
Numerical Model ◽  
Wave Height ◽  
Time Domain ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Wave Period ◽  
Irregular Waves ◽  
Parametric Rolling ◽  
Nonlinear Numerical Model

Abstract The numerical analysis of parametric rolling of medium-sized containership has been carried out. Target containership was modeled by using two different numerical models, which are nonlinear numerical model and simplified dynamic mathematical model respectively. The simulations were performed in full-loaded operating condition for regular and irregular waves. For regular waves, the analysis was conducted with a wide range of wave periods including the vicinity of the wave period expected to cause parametric rolling of the target containership. On the other hand, regarding irregular waves, the wave period range that is highly likely to occur according to significant wave height was selected and used as input values of wave spectrum for nonlinear time domain analysis. The analysis results are summarized as wave height versus wave period diagrams with the occurrences of parametric rolling motions for each speed. And also, time series based on time domain analysis are represented and compared between nonlinear numerical model and simplified dynamic mathematical model. In addition, the sensitivity of key parameters such as vessel speed, wave period, and roll damping to parametric rolling was investigated and estimated under operating condition. Finally, when the parametric rolling occurred, the characteristics of heave, pitch, and roll motions were analyzed. This study could be used as the basic data for determining the operational conditions for safe operation as well as initial design of the medium-sized containership.

Numerical Study on Sea Keeping Performances of Ship by Exact Linear 3-D Potential Method

2007 ◽  
Author(s):  
N. M. Golam Zakaria ◽  
M. S. Baree
Keyword(s):  
Frequency Domain ◽  
Wave Height ◽  
Time Domain ◽  
Domain Analysis ◽  
Potential Method ◽  
Frequency Domain Analysis ◽  
Numerical Calculations ◽  
Irregular Waves ◽  
Linear Potential ◽  
Time Domain Simulation

This paper deals with the numerical calculations of sea-keeping performances of ship in irregular sea condition. Here linear potential theory has been applied for describing the fluid motion and 3-D sink-source technique has been used to determine hydrodynamic forces for surface ship advancing in waves at constant forward speed. Numerical coding based on 3-D potential method has been tested in an extensive manner keeping an eye with the criteria recommended by various ITTC committees [1]. The numerical accuracy of the coding has been examined using some experiment results as well as some other contemporary numerical calculations given by some authors for the case of frequency domain analysis. Taking a typical Panamax Container Vessel and in order to simulate its sea-keeping performances in real sea condition, the frequency domain analysis has been performed. The result is then used for time domain simulation in short crested irregular waves. Unequal frequency spacing has been taken into account to get longer simulation time and also empirical nonlinear roll damping has been taken in the way of time domain simulation. From this time domain simulation, relative wave height has been calculated which could sometimes damage deck equipment as well as posing a risks to personnel in severe sea condition. The effect of speed & wave direction on relative wave height has been considered and finally the numerical results of the maximum and significant values of irregular relative wave heights for these conditions are discussed.

Study on a Time Domain Prediction Method for Wave Force: Application for a Point-Absorber WEC

2018 ◽  
Author(s):  
Qiao Li ◽  
Motohiko Murai
Keyword(s):  
Time Domain ◽  
Wave Spectrum ◽  
Time Domain Analysis ◽  
Wave Force ◽  
Domain Analysis ◽  
Irregular Waves ◽  
Floating Body ◽  
Control Force ◽  
Electric Generator ◽  
The Time Domain

There are a lot of numerical analysis for solving hydrodynamic responses of a floating body in the time domain. Most of them can give a theoretical solution in given irregular waves. It means, however, that the solution can be obtained only if the accurate irregular waves represented by the wave spectrum should be given. As we consider the actual operation, we know it is difficult to detect the accurate irregular waves instantaneously as needed accuracy in the most of the time domain analysis for feed backing the control force to the system. This paper proposes a new method to predict the practical wave force from the displacement of waves at a floating body in time domain analysis almost instantaneously. The method, that can apply to predict forces in wave energy converter with linear electric generator, helps us to choose the control force for convert more electric power in irregular waves. We confirm the algorithm and examine its effectiveness.

Time-domain analysis of dispersive transmission lines

1993 ◽  
Vol 3 (3) ◽  
pp. 581-591 ◽  
Author(s):  
Wojciech Gwarek ◽  
Malgorzata Celuch-Marcysiak
Keyword(s):  
Transmission Lines ◽  
Time Domain ◽  
Time Domain Analysis ◽  
Domain Analysis
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