URANS Simulation of ONR Tumblehome Parametric Rolling in Regular Head Waves

2019 ◽  
Author(s):  
Zhiguo Zhang ◽  
Lixiang Guo ◽  
Shuang Wang ◽  
Ye Yuan ◽  
Can Chen
Keyword(s):  
Experimental Data ◽  
Time History ◽  
Head Wave ◽  
Ship Motions ◽  
Parametric Rolling ◽  
Wave Characteristic ◽  
Head Waves ◽  
History Of ◽  
Onr Tumblehome ◽  
Regular Head Waves

Abstract In this paper, an in-house CFD code HUST-Ship is used for the numerical simulation of parametric rolling phenomena of ONR Tumblehome in regular head wave. Preliminary resistance and roll decay simulations at Fr = 0.2 were carried out and compared with existed INSEAN experimental data. Following, three DOFs’ ship motions in regular head wave with an initial roll angle of 30 degrees was calculated to examine the possibility of occurrence of parametric rolling. Finally, a simulation without initial roll disturbance was performed to investigate its influence to the steady roll amplitude. By conducting fast Fourier transform of the time history of motions, forces and moments, the characteristics are analyzed and co-related with wave frequency. Results can be concluded that the in-house code has the ability to perform the parametric rolling simulation, and that the final steady roll amplitude is not affected by the initial disturbance. In addition, heave and pitch motions are dominantly affected by wave characteristic, roll frequency is about half that of wave, and that forces and moments in x direction exhibit high-order non-linearity.

Study of Wave Added Resistance and Motions of KCS in Waves With Different Wave Lengths

2019 ◽  
Author(s):  
Hao Guo ◽  
Decheng Wan
Keyword(s):  
Navier Stokes ◽  
Head Wave ◽  
Ship Motions ◽  
Added Resistance ◽  
Head Waves ◽  
Wide Range ◽  
Stokes Waves ◽  
The Relationship ◽  
Nonlinear Behaviors ◽  
Regular Head Waves

Abstract Estimating added resistance and motions of a ship in waves are essential to predict fuel consumption and speed loss. The added resistance and motions of the 3600 TEU KRISO container ship (KCS) in regular head waves under different wavelengths are investigated using Reynolds-Averaged Navier-Stokes (RANS) method. Volume of Fluid (VOF) method is applied to capture the free surface. The in-house computational fluid dynamics solver, naoe-FOAM-SJTU, is used to compute the added resistance and motions of KCS in regular head waves. Firstly, the first-order Stokes waves in deep water are adopted and generated in naoe-FOAM-SJTU as a numerical wave tank. Secondly, it is presented that the KCS with a Froude number of 0.261 advances in these waves. Regular wave conditions with a wide range of wavelength (0.65 < λ/L < 1.95) are considered. The variations of resistance, pitch and heave show good agreement with experimental results. To investigate nonlinear behaviors of predicted results, Fast Fourier Transform (FFT) is applied to analyze the results of resistance, heave and pitch with in head wave (μ = 180°). KCS with and without motions is also compared to investigate the relationship between components of resistance and wavelengths. The results of added resistances show that the added resistance of KCS is mainly induced by ship diffraction in short waves. The wave diffraction is not affected by wave frequency. In addition, CFD can accurately calculate the problem on added resistance and ship motions.

Characteristics of a Simple Energy Absorption Transducer

1986 ◽  
Vol 108 (3) ◽  
pp. 676-683 ◽  
Author(s):  
B. T. Beck ◽  
G. L. Wedekind
Keyword(s):  
Experimental Data ◽  
Heat Flux ◽  
Laser Radiation ◽  
Steel Substrate ◽  
Time History ◽  
Radiation Absorption ◽  
Flux Analysis ◽  
Manganese Phosphate ◽  
History Of ◽  
Arbitrary Location

This paper presents the results of an investigation into a simple technique developed primarily for evaluating surface coating effectiveness for the absorption of a nonuniform laser radiation heat flux. Analysis suggests that if the transducer sensor is designed appropriately, and the experimental data analyzed in a particular manner, the temperature–time history of the transducer need be measured at only a single arbitrary location. These conclusions are also supported by experimental measurements of laser radiation absorption at a wavelength of 10.6 μm for polished copper, polished steel, and for a manganese–phosphate coating on a steel substrate. The absorptivities measured for the polished copper and steel agree well with other experimental data in the literature. Limitations of the measurement technique, resulting from the temperature dependence of the transducer material properties, radiation absorptivity, and combined convective and radiative heat flux, are also investigated theoretically and experimentally.

Numerical Modelling of Automatic Mooring Winches Applied to Moored Ships in Harbours

2008 ◽  
Author(s):  
Joa˜o Alfredo Santos
Keyword(s):  
Numerical Model ◽  
Numerical Modelling ◽  
Vertical Component ◽  
Ship Motions ◽  
Head Waves ◽  
Constant Tension ◽  
Vertical Breakwater ◽  
Regular Head Waves ◽  
Exposed Location

In order to control excessive motions of moored ships, automatic mooring winches, namely constant tension winches and automatic tension winches, have been employed. It has been common practice the recovering force in automatic tension winches never becoming lower than one third of the rendering force. However, the existence of such a non-zero recovering force implies that the cable where that force is applied to may be counteracting the rendering force produced on an opposing cable by another winch. Ideally, winches should only produce forces to reduce ship motions, hence the recovering force should be zero. This paper describes the use of a numerical model for moored ship behaviour in the study of the effects of automatic tension winches in the motion amplitudes of a 108 416 m3 displacement ship moored in two different conditions: a) alone at an exposed location; b) 30 m apart from a vertical breakwater. Additional cables connected to automatic mooring winches are considered and the change from idealized conditions where the cables apply forces on the ship with no vertical component to realistic conditions where such component exists is investigated as well as the influence of the recovering force on the ship motions for the ship subject to regular head waves.

Numerical and Experimental Study of the Parametric Rolling of a Fishing Vessel in Regular Head Waves

2013 ◽  
Vol 155 (A4) ◽  
Keyword(s):  
Degrees Of Freedom ◽  
Assessment Tool ◽  
Prediction Method ◽  
Theory Model ◽  
Design Stage ◽  
Ship Motions ◽  
Fishing Vessel ◽  
Parametric Rolling ◽  
Strip Theory ◽  
Head Waves

The dynamic behaviour of a fishing vessel in waves is studied in order to reveal its parametric rolling characteristics. This paper presents experimental and numerical results in longitudinal regular waves. The experimental results are compared against the results of a time-domain non-linear strip theory model of ship motions in six degrees-of-freedom. These results contribute to the validation of the parametric rolling prediction method, so that it can be used as an assessment tool to evaluate both the susceptibility and severity of occurrence of parametric rolling at the early design stage of these types of vessels.

NUMERICAL AND EXPERIMENTAL STUDY OF THE PARAMETRIC ROLLING OF A FISHING VESSEL IN REGULAR HEAD WAVES

2021 ◽  
Vol 155 (A4) ◽  
Author(s):  
E Uzunoglu ◽  
S. Ribeiro E Silva ◽  
C. Guedes Soares ◽  
R. Zamora ◽  
L. Perez Rojas
Keyword(s):  
Degrees Of Freedom ◽  
Assessment Tool ◽  
Prediction Method ◽  
Theory Model ◽  
Design Stage ◽  
Ship Motions ◽  
Fishing Vessel ◽  
Parametric Rolling ◽  
Strip Theory ◽  
Head Waves

The dynamic behaviour of a fishing vessel in waves is studied in order to reveal its parametric rolling characteristics. This paper presents experimental and numerical results in longitudinal regular waves. The experimental results are compared against the results of a time-domain non-linear strip theory model of ship motions in six degrees-of-freedom. These results contribute to the validation of the parametric rolling prediction method, so that it can be used as an assessment tool to evaluate both the susceptibility and severity of occurrence of parametric rolling at the early design stage of these types of vessels.

Application of Volterra Series Analysis for Parametric Rolling in Irregular Seas

2014 ◽  
Vol 58 (02) ◽  
pp. 97-105
Author(s):  
Hisham Moideen ◽  
Abhilash Somayajula ◽  
Jeffrey M. Falzarano
Keyword(s):  
Volterra Series ◽  
Irregular Waves ◽  
Parametric Roll ◽  
Peak Period ◽  
Parametric Rolling ◽  
Motion Sensitivity ◽  
Direct Excitation ◽  
Head Waves ◽  
Metacentric Height ◽  
Regular Head Waves

Parametric roll is a phenomenon in which there is a large rolling motion of a ship even when the ship is moving into head seas with no direct excitation. It is a nonlinear dynamic phenomenon of a ship rolling system with nonlinearities in the stiffness as well as the damping terms. Parametric roll of container ships in head seas is a relatively new problem, which has gained lot of importance after the catastrophic incidence of APL China in 1998. Analysis of parametric roll of container ships in regular head waves has been studied extensively. However, the ships do not encounter regular waves in the ocean. So, it is necessary to study how important parametric roll is in irregular seas. To study this, it is first important to model the variation of metacentric height in irregular waves, which is nonlinear as a result of the influence of underwater geometry and the motions of the ship in a seaway. In this work, the change of metacentric height (GM) in irregular waves has been modeled using a Volterra series approach. This transfer function for metacentric height (GM) is used to study parametric rolling of ships in irregular waves. Based on this study, roll motion sensitivity to the spectral peak period and significant wave height has been carried out.

Modeling of Advanced Combat Helmet Under Ballistic Impact

2015 ◽  
Vol 82 (11) ◽  
Author(s):  
Y. Q. Li ◽  
X. G. Li ◽  
X.-L. Gao
Keyword(s):  
Experimental Data ◽  
Time History ◽  
Ballistic Impact ◽  
Medium Size ◽  
Lateral Impact ◽  
Ballistic Performance ◽  
Ballistic Impacts ◽  
Large Size ◽  
History Of ◽  
Head Form

The use of combat helmets has greatly reduced penetrating injuries and saved lives of many soldiers. However, behind helmet blunt trauma (BHBT) has emerged as a serious injury type experienced by soldiers in battlefields. BHBT results from nonpenetrating ballistic impacts and is often associated with helmet back face deformation (BFD). In the current study, a finite element-based computational model is developed for simulating the ballistic performance of the Advanced Combat Helmet (ACH), which is validated against the experimental data obtained at the Army Research Laboratory. Both the maximum value and time history of the BFD are considered, unlike existing studies focusing on the maximum BFD only. The simulation results show that the maximum BFD, the time history of the BFD, and the shape and size of the effective area of the helmet shell agree fairly well with the experimental findings. In addition, it is found that ballistic impacts on the helmet at different locations and in different directions result in different BFD values. The largest BFD value is obtained for a frontal impact, which is followed by that for a crown impact and then by that for a lateral impact. Also, the BFD value is seen to decrease as the oblique impact angle decreases. Furthermore, helmets of four different sizes—extra large, large, medium, and small—are simulated and compared. It is shown that at the same bullet impact velocity the small-size helmet has the largest BFD, which is followed by the medium-size helmet, then by the large-size helmet, and finally by the extra large-size helmet. Moreover, ballistic impact simulations are performed for an ACH placed on a ballistic dummy head form embedded with clay as specified in the current ACH testing standard by using the validated helmet model. It is observed that the BFD values as recorded by the clay in the head form are in good agreement with the experimental data.

Growth and translation of a liquid-vapour compound drop in a second liquid. Part 2. Heat transfer

1989 ◽  
Vol 209 ◽  
pp. 639-660 ◽  
Author(s):  
S. T. Vuong ◽  
S. S. Sadhal
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Finite Difference Methods ◽  
Time History ◽  
Immiscible Liquid ◽  
Transport Processes ◽  
Contact Heat ◽  
Contact Heat Exchange ◽  
History Of ◽  
Single Compound

The present work is a comprehensive theoretical study of the heat transfer associated with a 3-singlet compound drop that is growing because of change of phase. The geometry is the same as in Part 1, i.e. a vapour bubble partially surrounded by its own liquid in another immiscible liquid. The attempt here is to gain fundamental understanding of the transport processes that take place in connection with direct-contact heat exchange. The fluid dynamics associated with its growth and translation is treated in Part 1. Here, that flow field solution is used to obtain the temperature field and hence the evaporation rate. The energy equation for the system consisting of a single compound drop is solved numerically by finite-difference methods. The results give the complete time history of evaporation of the drop. In addition, useful quantities such as the Nusselt number are given and compared with existing experimental data. Most of the results have good agreement with experimental data.

Numerical Simulation of Maneuvering of "Naniwa-maru," A Full-scale Reconstruction of Sailing Trader of Japanese Heritage

2003 ◽  
Author(s):  
Yutaka Masuyama ◽  
Kensaku Nomoto ◽  
Akira Sakurai
Keyword(s):  
Numerical Simulation ◽  
Equations Of Motion ◽  
Time History ◽  
Ship Motions ◽  
Measured Time ◽  
Generic Class ◽  
History Of ◽  
Heading Angle ◽  
Ship Performance ◽  
Rudder Angle

Numerical simulation of maneuvering of “Naniwa-maru" was performed to clarify the maneuver characteristics in particular with wearing operation. "Naniwa-maru" belongs to a type called Higaki-kaisen, and the Higaki-kaisen is a type of the more generic class of vessels named "Bezai-ship". Bezai-ship are typical Japanese sailing traders in the 18th to the mid- 19th century which have different appearance and construction from those of Western tall ships. The present paper shows the numerical simulation of her wearing operation, and the results compared with the measured data. The equations of motion dealt with coupled ship motions of surge, sway, roll and yaw with co-ordinate system using horizontal body axes. The numerical simulation indicates ship response according to the measured time history of rudder angle, and shows the ship trajectory and the sailing state parameters such as heading angle, leeway angle, heel angle and velocity. The calculated results indicated the ship performance very well.

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