Damping Coefficients for Extreme Rolling and Capsize: An Analytical Approach

2000 ◽  
Vol 44 (01) ◽  
pp. 1-13 ◽  
Author(s):  
K. J. Spyrou ◽  
J. M. T. Thompson
Keyword(s):  
Hamiltonian System ◽  
Closed Form ◽  
Large Amplitude ◽  
Analytical Approach ◽  
Roll Motion ◽  
Elliptic Type ◽  
Roll Damping ◽  
Damping Coefficients ◽  
Linear And Nonlinear ◽  
The Law

A method to identify the law of roll motion decay from extreme angles is presented based on perturbations of the elliptic-type solutions of the corresponding Hamiltonian system. Restoring polynomials up to the 7th order are considered. It is shown that the decay law can be expressed in closed form for up to quintic restoring. The method should be especially useful for deriving linear and nonlinear roll damping coefficients in the context of ship capsize investigations where the large amplitude behavior, near to the angle of vanishing stability, needs to be taken into account.

scholarly journals DETERMINATION OF LINEAR AND NONLINEAR ROLL DAMPING COEFFICIENTS OF A SHIP SECTION USING CFD

Brodogradnja ◽  
2019 ◽  
Vol 70 (4) ◽  
pp. 17-33 ◽  
Author(s):  
Soon-Seok Song ◽  
◽  
Sang-Hyun Kim ◽  
Kwang-Jun Paik ◽  
Keyword(s):  
Roll Damping ◽  
Damping Coefficients ◽  
Linear And Nonlinear

Modelling of Roll Damping Effects for a Fishing Vessel With Forward Speed

2015 ◽  
Author(s):  
K. G. Aarsæther ◽  
D. Kristiansen ◽  
B. Su ◽  
C. Lugni
Keyword(s):  
Large Amplitude ◽  
Well Being ◽  
Roll Motion ◽  
Ship Motions ◽  
Limiting Factor ◽  
Real Problem ◽  
Forward Speed ◽  
Roll Damping ◽  
Damping Effects ◽  
Wave Induced

Vessels in the ocean-going fishing fleet are in general operating in almost all weather conditions. This includes operation in high sea-states which may lead to large amplitude ship motions, depending on the seakeeping characteristics of the vessel. Wave-induced ship motions are important factors for the safety and well-being of fishermen at work. Generally, potential flow theory overpredicts wave-induced roll motion amplitudes for conventional ship hulls. This is due to the presence of viscous damping effects in reality. Large amplitude roll motion of ships can be a real problem if no anti-rolling devices (e.g. bilge keels, anti-rolling tanks or roll-damping fins) are installed, as the roll damping coefficient of a ship is the limiting factor for the resonant roll motion amplitudes. The different components of roll damping for a ship at forward speed were investigated by Ikeda et al. [1], [2] and [3] and updated guidelines for numerical estimation of roll damping have been presented by the International Towing Tank Conference [4], where a component discrete type method for estimation of the damping is suggested. The different roll-damping components of Ikeda et al. has been complemented by skeg damping for smooth hulls [5]. This paper presents comparison between model experiments and the numerical results obtained from the guidelines [4] where the effects of bilge-keels and skeg are isolated.

A Piecewise Model for Prediction of Large Amplitude Total Ship Roll Damping

2011 ◽  
Author(s):  
Christopher C. Bassler ◽  
Arthur M. Reed ◽  
Alan J. Brown
Keyword(s):  
Large Amplitude ◽  
Roll Motion ◽  
Practical Implementation ◽  
Roll Damping ◽  
Damping Characteristics ◽  
Ship Roll ◽  
Piecewise Model ◽  
Physical Changes ◽  
Physical Phenomena ◽  
Bilge Keel

A piecewise model is presented to model total ship roll damping, with considerations for large amplitude roll motion effects, such as bilge keel interaction with the free-surface. The model is based on the consideration of distinct ship-specific physical phenomena, such as bilge keel emergence. Abrupt physical changes occur with these events, resulting in significant changes in the damping characteristics of the system. Without these considerations, roll motion may be under-predicted. Some additional considerations needed for the practical implementation of the proposed piecewise model are also discussed.

A Mathematical Model for Roll Damping Prediction

2015 ◽  
Author(s):  
Henry Piehl ◽  
Ould el Moctar
Keyword(s):  
Mathematical Model ◽  
Regression Analysis ◽  
Shape Parameter ◽  
Roll Motion ◽  
Damping Properties ◽  
Roll Damping ◽  
Ship Hulls ◽  
Damping Coefficients ◽  
Analytic Expression

A ship in seaway is always prone to roll motion. For the safety of personnel, ship and cargo it is essential to optimize the roll damping properties of the hull shape in order to prevent exceeding roll angles. Therefore, a tool for the prediction of roll damping is an important requirement during the design phase of ship hulls. The objective of this study is to use regression analysis and numerical simulation of roll motion to develop an analytic expression for the determination of roll damping. The development procedure starts with a variation of several hull shape parameter that influence the roll damping. For each of the parameter variants, a numerical roll simulation is conducted and the according roll damping coefficients are determined by time series analysis. Finally, regression analysis is applied to the computed results in order to derive a mathematical model that allows to determine the roll damping coefficient depending on the hull shape parameter.

scholarly journals Bilge Keel Induced Roll Damping of an FPSO With Sponsons

2016 ◽  
Author(s):  
Babak Ommani ◽  
Nuno Fonseca ◽  
Trygve Kristiansen ◽  
Christopher Hutchison ◽  
Hanne Bakksjø
Keyword(s):  
Free Surface ◽  
Two Dimensions ◽  
The Body ◽  
Proximity Effects ◽  
Roll Damping ◽  
Damping Coefficients ◽  
Free Decay ◽  
Strip Theory ◽  
Decay Tests ◽  
Bilge Keel

The bilge keel induced roll damping of an FPSO with sponsons is investigated numerically and experimentally. The influence of the bilge keel size, on the roll damping is studied. Free decay tests of a three-dimensional ship model, for three different bilge keel sizes are used to determine roll damping coefficients. The dependency of the quadratic roll damping coefficient to the bilge keel height and the vertical location of the rotation center is studied using CFD. A Navier-Stokes solver based on the Finite Volume Method is adopted for solving the laminar flow of incompressible water around a section of the FPSO undergoing forced roll oscillations in two-dimensions. The free-surface condition is linearized by neglecting the nonlinear free-surface terms and the influence of viscous stresses in the free surface zone, while the body-boundary condition is exact. An averaged center of rotation is estimated by comparing the results of the numerical calculations and the free decay tests. The obtained two-dimensional damping coefficients are extrapolated to 3D by use of strip theory argumentations and compared with the experimental results. It is shown that this simplified approach can be used for evaluating the bilge keel induced roll damping with efficiency, considering unconventional ship shapes and free-surface proximity effects.

scholarly journals أوامر في سورة النساء المتعلقة بأحكام الأسرة; دراسة تطبيقية

2020 ◽  
Vol 1 (1) ◽  
pp. 180-199
Author(s):  
Awal Rifai ◽  
Usamah Maming
Keyword(s):  
Family Life ◽  
Social Life ◽  
Analytical Approach ◽  
The Family ◽  
The Law

Surah An-Nisa is one of the longest madaniah surah, and is one full of provisions of sharia laws that govern all matters both internal and external ones for Muslims. Among the prominence of this noble surah is that it tells a lot about important things related to women, household, family, country, and social life. In this surah, there are commands and prohibitions in various matters. The purpose of this study was to extract imperative sentences related to family life and then briefly identify the rules that became the base for these commands. The researcher employed an inductive and analytical approach by extrapolating Surah Al-Nisa, taking imperative sentences related to family life, and explaining the law which is concluded from it. Researcher finds, among the most important of the most important ones are as follows: understanding the meaning of al-amr (command) which is a request to do something in the form of superiority. There are two types of amr: direct and indirect. The number of amr related to the family in the surah is seventeen.

Closed-form analytical approach for calculating noise contours of directive aircraft noise sources

2021 ◽  
Author(s):  
Daniel C. Amargianitakis ◽  
Rodney H. Self ◽  
Antonio J. Torija ◽  
Anderson Proenca ◽  
Athanasios P. Synodinos
Keyword(s):  
Closed Form ◽  
Analytical Approach ◽  
Aircraft Noise ◽  
Noise Sources

Experimental Investigation of Hydrodynamic Coefficients of a Wave-Piercing Tumblehome Hull Form

2007 ◽  
Author(s):  
Christopher C. Bassler ◽  
Jason B. Carneal ◽  
Paisan Atsavapranee
Keyword(s):  
Experimental Investigation ◽  
System Modeling ◽  
Flow Simulation ◽  
Roll Damping ◽  
Hull Form ◽  
Damping Coefficients ◽  
Calm Water ◽  
Forced Roll ◽  
Future Work ◽  
Damping Model

A systematic series of calm-water forced roll model tests were performed over a range of forward speeds using an advanced tumblehome hull form (DTMB model #5613-1) to examine the mechanisms of roll damping. This experimental investigation is part of an ongoing effort to advance the capability to assess seakeeping, maneuvering, and dynamic stability characteristics of an advanced surface combatant. The experiment was performed to provide data for development and validation of a semi-empirical roll damping model for use in validation of ship motion and viscous flow simulation codes, as well as to provide a basis for future work with additional experiments, contributing to the development of an improved analytical roll damping model. Two hull configurations were tested: barehull with skeg, and bare hull with skeg and bilge keels. Measurements of forces and moments were obtained over a range of forward speeds, roll frequencies, and roll amplitudes. Stereo particle-image velocimetry (SPIV) measurments were also taken for both zero and forward speeds. Test data was used to calculate added mass/inertia and damping coefficients. Two different system modeling techniques were used. The first method modeled the system as an equivalent linearly-damped second-order harmonic oscillator with the time-varying total stiffness coefficient considered linear. The second technique used equivalent linear damping, including higher-order Fourier components, and a non-linear stiffness formulation. Results are shown, including plots of added inertia and damping coefficients as functions of roll frequency, roll amplitude, and forward speed and SPIV measurements. Trends from the experimental data are compared to results from traditional component roll damping formulations for conventional hull from geometries and differences are discussed.

scholarly journals PIDANA PENGAWASAN TERHADAP ANAK YANG BERHADAPAN DENGAN HUKUM DALAM SISTEM PEMIDANAAN DI INDONESIA

2013 ◽  
Vol 2 (3) ◽  
Author(s):  
I Putu Suwarsa
Keyword(s):  
Criminal Law ◽  
Analytical Approach ◽  
Criminal Policy ◽  
Legal Protection ◽  
Comparative Approach ◽  
Legal Concept ◽  
Normative Approach ◽  
Positive Law ◽  
The Law

ABSTRACTThis research was conducted with the normative approach legislation. Factualapproach, analytical approach to the legal concept of a comparative approach in thecriminal judicial oversight of Children in Conflict with the Law in the criminal sistem inIndonesia.In formulating criminal law criminal policy oversight of Children in Conflict withthe Law in the guidance sistem of positive law in Indonesia, consists of 3 major topics:First, the substance of Children in Conflict with the Law into law in Indonesia, Second,Determination of sanctions / penalties against Children in Conflict with the Law inIndonesia's criminal law policy, Third, criminal oversight of Children in Conflict with theLaw and its relevance to the theory of punishment in modern criminal law in Indonesia.Criminal oversight of Children in Conflict with the Law as the integrative goals ofpunishment in accordance with the ideas and correctional sistem discussed 3 subjectsnamely: First, criminal oversight of anal naughty review of aspects of the integrativetheory of punishment, Second, Criminal oversight of Children in Conflict with the Lawreview of aspects of correctional sistem, Third, Criminal oversight of Children in Conflictwith the Law in terms of aspects of legal protection and benefit of the criminal lawrequirement for social welfare (children). And its application by all law enforcementcomponents and related institutions involved in handling cases of children in conflict withthe law in coaching children in prison.

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