scholarly journals Ship’S Rolling Amplitude as a Significant Factor Influencing Liquid Sloshing in Partly Filled Tanks / Amplituda Kołysań Statku Jako Istotny Parametr W Badaniach Zjawiska Sloshingu W Niepełnych Zbiornikach Okrętowych

2012 ◽  
Vol 21 (1) ◽  
pp. 63-76
Author(s):  
Przemysław Krata ◽  
Wojciech Wawrzyński
Keyword(s):  
Numerical Simulations ◽  
Liquid Sloshing ◽  
Liquid Motion ◽  
Dynamic Approach ◽  
Non Linear ◽  
Heeling Moment

Abstract The study considers ship’s rolling amplitude as one of the key parameters influencing liquid sloshing in partly filled tanks during sea voyage. This issue is strictly related to the safety of navigation matters and belongs to the group of non-linear hydrodynamic phenomena. The presented investigation is focused on the estimation of typical and extreme rolling amplitude of a vessel in terms of dynamic approach towards liquid motion onboard ships. The number of exemplary numerical simulations of liquid sloshing taking place in moving tanks is carried out and the heeling moment due to liquid sloshing is obtained.

scholarly journals Dynamic Heeling Moment Due to Liquid Sloshing in a Rectangular Tank of Different Dimensions and Elevation in Ship’S Hull / Dynamiczny Moment Przechylający Od Swobodnych Powierzchni Cieczy W Prostokątnym Zbiorniku Okrętowym O Różnych Wymiarach I Lokalizacji Pionowej

2012 ◽  
Vol 21 (1) ◽  
pp. 51-62
Author(s):  
Przemysław Krata ◽  
Jacek Jachowski
Keyword(s):  
Numerical Simulations ◽  
Liquid Sloshing ◽  
Liquid Motion ◽  
Dynamic Approach ◽  
Rectangular Tank ◽  
Different Dimensions ◽  
Sloshing Phenomenon ◽  
The Stability ◽  
Heeling Moment

Abstract Liquid sloshing phenomenon taking place in partly filled ships’ tanks directly affects the stability of a vessel and her safety on seaway, however, only static calculations are carried out onboard ships nowadays. The presented investigation is focused on dynamic approach towards liquid motion onboard ships. The set of numerical simulations of liquid sloshing taking place in moving tanks is carried out in terms of tank’s dimensions and its elevation within ship’s hull. A number of characteristics of the heeling moment due to liquid sloshing is obtained and analyzed.

Numerical Simulations as a Reliable Alternative for Landmine Explosion Studies: The AUTODYN Approach

2010 ◽  
Author(s):  
Stephanie Follett ◽  
Amer Hameed ◽  
S. Darina ◽  
John G. Hetherington
Keyword(s):  
Experimental Data ◽  
Numerical Simulations ◽  
Reasonable Agreement ◽  
Specific Impulse ◽  
Numerical Procedure ◽  
Ground Surface ◽  
Time Of Arrival ◽  
Linear Dynamics ◽  
Non Linear

In order to validate the numerical procedure, the explosion of a mine was recreated within the non-linear dynamics software, AUTODYN. Two models were created and analysed for the purposes of this study — buried and flush HE charge in sand. The explosion parameters — time of arrival, maximum overpressure and specific impulse were recorded at two stand-off distances above the ground surface. These parameters are then compared with LS-DYNA models and published experimental data. The results, presented in table format, are in reasonable agreement.

scholarly journals Multi-physics phenomena influencing the performance of the car horn

2019 ◽  
Vol 38 (2) ◽  
pp. 544-557 ◽  
Author(s):  
Cristian Medè ◽  
Alberto Doria ◽  
Paolo Munaretto ◽  
Jorge SG Valdecasas
Keyword(s):  
Numerical Simulations ◽  
Mechanical Energy ◽  
Input Voltage ◽  
Harmonic Excitation ◽  
Electromagnetic Energy ◽  
Electrical Parameters ◽  
Detailed Model ◽  
Non Linear ◽  
Linear Effects ◽  
Car Horn

Usually cars are equipped with disk horns. In these devices electromagnetic energy is converted into mechanical energy of two nuclei that vibrate and impact each other – the impacts excite the disk that radiates sound. This paper aims at understanding the results of acoustic tests carried out on horns with different excitation voltages and different mounting brackets. Since many non-linear phenomena are inherent in the vibrations of the nuclei, a detailed model of the electromechanical system is developed. Results show the dependence of operating frequency on the input voltage and the role played by the various mechanical and electrical parameters on the dynamics of the horn. Particular non-linear effects, like sub-harmonic excitation, are presented and discussed. A general agreement between experimental results and numerical simulations is found.

scholarly journals Kelvin-Helmholtz Instabilities and the Emission Knots in Herbig-Haro Jets

1997 ◽  
Vol 182 ◽  
pp. 335-342 ◽  
Author(s):  
S. Massaglia ◽  
M. Micono ◽  
A. Ferrari ◽  
G. Bodo ◽  
P. Rossi
Keyword(s):  
Numerical Simulations ◽  
Astrophysical Jets ◽  
General Applicability ◽  
Simple Assumption ◽  
Linear Evolution ◽  
Radiation Losses ◽  
Non Linear ◽  
Constant Heating ◽  
Non Equilibrium

We discuss the non-linear evolution of Kelvin-Helmholtz instabilities in Herbig-Haro jets performing numerical simulations by means of a PPM hydro-code modified as to include non-equilibrium, optically thin, radiation losses and heating. In this paper we discuss in particular the effects of different functional dependences of heating on density. The results obtained show a weak dependency of the instability evolution on the different forms of the heating function, that is largely unknown, therefore the simple assumption of constant heating, adopted in previous papers on this matter, does not lead to severe limitations on the general applicability of the results to the astrophysical jets and, in particular, to the origin of the emission knots.

Numerical vs. Experimental Predictions of Yaw Motion of Single Point Moored Vessel

2005 ◽  
Author(s):  
Mathieu Brotons ◽  
Philippe Jean
Keyword(s):  
Numerical Simulation ◽  
Differential Equations ◽  
Numerical Simulations ◽  
Time Domain ◽  
Model Tests ◽  
Linear Differential Equations ◽  
Integration Scheme ◽  
Engineering Model ◽  
Non Linear ◽  
Linear Differential

The accurate prediction of SPM vessel yaw motion is important to its mooring system design. Inconsistencies have been observed between the numerical and model test predictions of offloading responses. In some cases, the numerical simulation predicted unstable yaw behavior of the vessel (fishtailing) while the model tests did not show such instability. This discrepancy between experiment and theory casts doubt as to whether the numerical simulation predicts correctly the vessel yaw motion. The work presented in this paper investigates the following two hypotheses to possibly explain the non-expected fishtailing in the numerical simulations: The mooring software may not accurately integrate non-linear differential equations that describe the yaw motion of the SPM vessel. Some damping terms may be under-estimated in the software (user input issue). To validate the integration scheme of the system of non-linear differential equations as implemented in the mooring software, a stability analysis has been conducted on a shuttle tanker moored to a West Africa deep water buoy. Variations of parameters like the hawser length, its axial stiffness and the vessel’s drag coefficients have been studied to explore their impacts on the vessel yaw stability. The approach is to identify without performing any time domain simulations, the domains of stability by linearizing the differential equations of SPM vessel’s yaw motion around its equilibrium point. The validity of the developed approach is then confirmed by performing time domain simulations of the same case. The second conjecture which may explain the non-expected fishtailing in numerical simulations was that some damping terms may be under-estimated. A semi empirical formula for the drag moment can be derived from rotation tests and comparisons were performed with the engineering model implemented in the mooring analysis software. The results show that by calibrating this damping term with the one derived from the experiments, the numerical simulations would match the stable yaw motion behavior as predicted during model tests. Following the above findings, a tool has been developed to fit the yaw drag moment engineering model based on experimental measurements, for any case of mooring analysis.

A non-linear model of sulphation of porous stones: Numerical simulations and preliminary laboratory assessments

2008 ◽  
Vol 9 (1) ◽  
pp. 14-22 ◽  
Author(s):  
C. Giavarini ◽  
M.L. Santarelli ◽  
R. Natalini ◽  
F. Freddi
Keyword(s):  
Numerical Simulations ◽  
Linear Model ◽  
Non Linear

Evaluation of Gun Support Structure Using Equivalent Dynamic Approach in Non Linear FEA

2013 ◽  
Vol 376 ◽  
pp. 331-335
Author(s):  
Sunil Shukla ◽  
H. S. Deshmukh ◽  
Patil Vinaay ◽  
B.A. Thite A.
Keyword(s):  
Standard Operating Procedure ◽  
Dynamic Loads ◽  
Robot Arm ◽  
Dynamic Approach ◽  
Contact Algorithm ◽  
Standard Operating ◽  
Non Linear ◽  
Single Structure ◽  
Cost Efficient ◽  
Linear Geometry

Robot Gun structure is an efficient way in which multiple welds can be done simultaneously. However mounting several weld guns on a single structure induces a variety of dynamic loads, especially during movement of the robot arm as it maneuvers to reach the weld locations.The primary idea employed in this paper, is to model those dynamic loads as equivalent G force loads in FEA. This approach will be on the conservative side, and will be saving time and subsequently cost efficient. The approach of the paper is towards creating a standard operating procedure (SOP) when it comes to analysis of such structures, with emphasis on deploying various technical aspects of FEA such as Non Linear Geometry, Multipoint Constraint Contact Algorithm, Multizone meshing .

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