Numerical Simulation of Ship Turning in Level Ice

2010 ◽  
Author(s):  
Biao Su ◽  
Kaj Riska ◽  
Torgeir Moan
Keyword(s):  
Numerical Simulation ◽  
Numerical Method ◽  
Field Measurements ◽  
Full Scale ◽  
Ship Maneuverability ◽  
Ice Conditions ◽  
Level Ice ◽  
Ship Performance ◽  
Scale Data ◽  
Good Agreement

The ice-worthy ship must have a verifiable turning ability in the specified ice conditions. At present, most studies on ship maneuverability in ice are conducted by field measurements. In this paper a numerical method which is introduced for predicting ship performance in level ice, is applied to simulate ship turning in level ice. A real icebreaker is modeled in the simulation program. The calculated results are analyzed and compared with the full-scale data measured during turning tests. A good agreement is achieved.

scholarly journals Vibro-Acoustic Numerical Simulation for Analyzing Floor Noise of a Multi-Unit Residential Structure

2019 ◽  
Vol 9 (20) ◽  
pp. 4289 ◽  
Author(s):  
Sangki Park
Keyword(s):  
Numerical Simulation ◽  
Numerical Analysis ◽  
Numerical Model ◽  
South Korea ◽  
Acoustic Analysis ◽  
Measurement Data ◽  
Field Measurements ◽  
Story Structure ◽  
Residential Structures ◽  
Good Agreement

In South Korea, the construction of new multi-unit residential structures has been continuously increasing in order to accommodate multiple households in single structures. However, the presence of walls and floors shared with neighbors makes these structures exceptionally vulnerable to floor noise transmission when the noise of everyday life occurs. In particular, South Korea has many social problems associated with such floor noise, which require the utmost attention and immediate resolution. In this study, a 17-story structure was selected as a test structure. Field measurements were carried out. A numerical model for the 17-story structure was developed in order to perform a vibro-acoustic analysis. The validation of the numerical model comparing with the field measurement data results shows a good agreement. Finally, it is concluded that numerical analysis can be applied to resolve floor noise problems arising in multi-unit residential structures.

Model Tests on a Spar in Level Ice and Ice Ridge Conditions

2009 ◽  
Author(s):  
John Murray ◽  
Stephane LeGuennec ◽  
Don Spencer ◽  
Chang K. Yang ◽  
Wooseuk Yang
Keyword(s):  
Full Scale ◽  
Scale Model ◽  
Test Facility ◽  
Mooring System ◽  
Scaling Effects ◽  
Line System ◽  
Restoring Forces ◽  
Ice Conditions ◽  
Ice Loads ◽  
Level Ice

1:30 and 1:50 model-scale ice tests of an ice-resistant Spar design were carried out to determine the loads on the Spar in level ice and ice ridges. Due to limitations in the depth of the ice test facility, the hull draft and mooring system were truncated. The 1:30 scale model was towed through the ice on a fixed and compliant dynamometer. The stiffness characteristics of the compliant dynamometer matched the horizontal stiffness of the full-scale mooring system. The purpose of these tests was to compare the mooring and ice loads measured in fixed and compliant conditions. The 1:50 scale model was truncated by 70 m. Its mooring system was modeled using a four-line system designed to give the same global restoring forces as the full-scale mooring system. The model was fitted with vertical plates on the exterior of the hull to compensate for loss of added mass and added moment of inertia. A limited number of tests were carried out at the two model scales in the same ice conditions to investigate scaling effects. The mooring and ice loads measured in the fixed and compliant conditions were found to be similar, indicating that loads estimated, assuming the structure is fixed, provide good estimates. Good agreement between the two models was also found for the tests carried out in the same ice conditions, suggesting that the scaling effects may be negligible.

Full-Scale Maneuvering Tests in Level Ice of Canmar Kigoriak and Robert LeMeur

1986 ◽  
Vol 23 (02) ◽  
pp. 131-138
Author(s):  
Kin K. Tue-Fee ◽  
Arno J. Keinonen
Keyword(s):  
Full Scale ◽  
Level Ice ◽  
Scale Data ◽  
Comparable Size

This paper gives an overview of the extensive full-scale maneuvering tests carried out during the period of September 1979 to July 1980 and May to June 1981 on the icebreaker Canmar Kigoriak and during November to December 1982 and June 1983 on the Robert LeMeur. The icebreakers with spoon-shaped bow and reamers perform well, with the Robert LeMeur rivalling and Kigoriak surpassing the performance of conventional Canadian icebreakers of comparable size and power. The effects of heel on the turning performance of the ships were tested and are discussed. Due to the proprietary nature of the full-scale data, only some of the results are presented in this paper.

scholarly journals Numerical Simulation of a Polar Ship Moving in Level Ice Based on a One-Way Coupling Method

2020 ◽  
Vol 8 (9) ◽  
pp. 692
Author(s):  
Bao-Yu Ni ◽  
Zi-Wang Chen ◽  
Kai Zhong ◽  
Xin-Ang Li ◽  
Yan-Zhuo Xue
Keyword(s):  
Numerical Simulation ◽  
Failure Process ◽  
Coupling Method ◽  
Crack Propagation Process ◽  
Order Of Magnitude ◽  
Level Ice ◽  
Ice Failure ◽  
Ice Resistance ◽  
Ship Speed ◽  
Good Agreement

In most previous ice–ship interaction studies involving fluid effects, ice was taken as unbreakable. Building breakable level ice on water domain is still a big challenge in numerical simulation. This paper overcomes this difficulty and presents a numerical modeling of a ship moving in level ice on the water by using a one-way CFD-DEM (computational fluid dynamics-discrete element method) coupling method. The detailed numerical processes and techniques are introduced. The ice crack propagation process including radial and circular cracks have been observed. Numerical results are compared with previous experimental data and good agreement has been achieved. The results show that water resistance is an order of magnitude smaller than ice resistance during the ice-breaking process. Ice resistance shows strong oscillation along with ice failure process, which are affected by ship speed and ice thickness significantly.

A New Icebreaking Pattern for the Application in Numerical Simulation of Ship Performance in Level Ice

2018 ◽  
Author(s):  
Fang Li ◽  
Mikko Kotilainen ◽  
Floris Goerlandt ◽  
Pentti Kujala
Keyword(s):  
Numerical Simulation ◽  
Numerical Models ◽  
Computation Time ◽  
Ship Hull ◽  
Large Set ◽  
Ice Loads ◽  
Level Ice ◽  
Proper Definition ◽  
Definition Of ◽  
Ship Performance

For the evaluation of ship performance in ice and ice loads on the ship hull, numerical simulation methods have been increasingly developed in recent years. In these models, the shapes of ice cusps broken from the intact ice sheet are idealized as either part of a circle or a triangle. Effects arising from the geometry of the loading area are neglected or idealized. Since the proper definition of the geometry of ice cusps is one of the key factors in numerical models, this paper introduces a new icebreaking pattern based on theoretical deviation. The finite difference method is adopted to approximate the deflection field of the wedge plate. This model takes a large set of factors as input while consuming little computation time. The outcome provides some new features compared to previous models. The results are validated using full-scale measurements of ice cusps around a ship hull, based on stereo camera recording and image processing. The validation shows that the derived method is appropriate in predicting realistic icebreaking patterns. Hence, it is plausible that its implementation in numerical models for ship performance in level ice will lead to improved prediction of the ship performance and ice loads on the hull.

scholarly journals Propeller Hydrodynamic Characteristics in Oblique Flow by Unsteady Ranse Solver

2020 ◽  
Vol 27 (1) ◽  
pp. 6-17
Author(s):  
Hossein Nouroozi ◽  
Hamid Zeraatgar
Keyword(s):  
Numerical Method ◽  
Navier Stokes ◽  
Hydrodynamic Characteristics ◽  
Time Step ◽  
Sliding Mesh ◽  
Oblique Flow ◽  
Ranse Solver ◽  
Ship Performance ◽  
Thrust And Torque ◽  
Good Agreement

AbstractPropellers may encounter oblique flow during operation in off-design conditions. Study of this issue is important from the design and ship performance points of view. On the other hand, a propeller operating in oblique flow may sometimes result in a better propulsion efficiency. The main goal of the present study is to provide an insight on the propeller characteristics in the oblique flow condition. In this research, the performance of the DTMB 4419 propeller is studied by the numerical method based on solving Reynolds Averaged Navier–Stokes (RANS) equations in several inflow angles. The sliding mesh approach is used to model the rotary motion of the propeller. Initially, the numerical method is verified by grid and time step dependency analysis at various inflow angles. Additionally, computed results at zero inflow angle are compared with the available experimental data and good agreement is achieved. Finally, the forces and moments acting on the propeller are obtained for 0° to 30° inflow angles. It is concluded that the inflow angle up to 10° has no significant influence on the thrust and torque coefficients as well as the propeller efficiency. However, at high angles up to 30°, the thrust and torque coefficients increase as the inflow angle increases, which may result in a significant improvement of propeller efficiency.

Numerical simulation of the flow field in a bioreactor

2000 ◽  
Vol 41 (4-5) ◽  
pp. 207-210 ◽  
Author(s):  
S. Ester ◽  
X. Guo ◽  
A. Delgado
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Numerical Method ◽  
Mechanical Behaviour ◽  
Numerical Code ◽  
Measurement Instruments ◽  
Local Flow ◽  
Velocity Pressure ◽  
Detailed Picture ◽  
Good Agreement

In order to give detailed information about the local flow field in a bioreactor a numerical method has been developed. This method gives information about the velocity, pressure and temperature in each point of the reactor, avoiding the problems caused by placing measurement instruments inside. Comparisons of experiments and numerical results show good agreement. The functionality and physical fundamentals of this tool are described. This is followed by explaining a reasonable application of the numerical code in the field of biological reactors. The reactors considered are filled with polydisperse, spherical support particles. From the results of the simulation a detailed picture of a reactor's fluid mechanical behaviour is drawn. This includes the quantification of mechanical stresses on the biofilm surface as well as information about the inflow, outflow and channelling behaviour of a reactor. Furthermore the effect of polydisperse support carries in discussed.

Numerical Simulation of Ship-Ice Interaction

2019 ◽  
Author(s):  
Michael Huisman ◽  
Sandro Erceg ◽  
Rüdiger U. Franz von Bock und Polach ◽  
Thomas Rung ◽  
Sören Ehlers
Keyword(s):  
Numerical Simulation ◽  
Free Surface Flow ◽  
Computational Effort ◽  
Surface Flow ◽  
Total Resistance ◽  
Flow Solver ◽  
Broken Ice ◽  
Ice Conditions ◽  
Level Ice ◽  
Boltzmann Method

Abstract The increasing activities in arctic sea areas over the last years have led to a rising demand for numerical tools to design and evaluate ice-going ships. Numerical simulation of ship-ice interaction can be a suitable method for engineers to evaluate ship designs in early development phases. We present an efficient method to evaluate local and global loads on ships in level ice at moderate computational effort. The objective of this contribution is the holistic simulation of the icebreaking process along with the hydrodynamic interplay of the broken ice cups with the surrounding level ice and the hull. For this purpose, a free surface flow solver based upon the Lattice Boltzmann method is coupled to an icebreaking model and a contact-dynamic physics engine. Overall, the approach seeks to compute both local loads, acting on the ship hull, as well as the total resistance in ice. The direct simulation approach makes it possible to consider the load contributions of icebreaking and displacement separately and to analyze their contribution to the total resistance more precisely. Simulation results for a tanker in various ice conditions show significant differences in load distribution and can provide valuable information for the designer of ice-going ships.

Numerical Simulation of Ship Maneuverability in Wind and Current, With Escort Tugs

2005 ◽  
Vol 42 (04) ◽  
pp. 159-176
Author(s):  
Ye Li ◽  
Sander M Çalisal
Keyword(s):  
Numerical Simulation ◽  
Performance Criteria ◽  
Successful Operation ◽  
Ship Maneuvering ◽  
Ship Maneuverability ◽  
Different Types ◽  
Using Data ◽  
Ocean Environment ◽  
Hydrodynamics Coefficients ◽  
Good Agreement

A number of recent large-ship accidents have compelled naval architects and engineers to advance the research on ship maneuverability and the prediction of ship response in the ocean environment. In the meantime, new maneuverability standards have been developed and the International Maritime Organization (IMO) has also proposed one such standard. This standard provides four ship-maneuvering performance criteria, and its latest version is dated December 2002. Simulation technology, in particular the simulation of ship maneuvering, has advanced considerably in recent years with the advent of computers. Computer programs using either numerically computed or experimentally determined hydrodynamics coefficients have allowed an accurate simulation of ship maneuverability for different types of vessels. Relatively good agreement has been reported by various researchers between simulated results and those obtained from full-scale ship trials. It seems that simulation can now identify acceptable ship maneuvering performance in calm seas. However, the effects of wind and current and escort tug assistance have not been that well studied and reported, and they are always important factors for ship maneuvering especially in restricted waters. The numerical simulation program presented in this paper (UBCManeuver) has been validated using data on the Esso Osaka 278,000 DWT tanker, a ship well tested for regular maneuvering tests. UBCManeuver is able to identify IMO class and non-IMO class ships according to the most recent IMO standards for ship maneuverability. A good agreement was obtained between simulation and the sea trials reported for Esso Osaka. After the validation of the code, the course-keeping abilities of this ship in restricted waters were studied in calm seas and under wind and current conditions. The effect of escort tugs on such an operation has also been quantified and Esso Osaka's maneuvering performance around Vancouver harbor simulated. The limits of current and wind strengths for "successful" operation with and without escort tugs have then been established. In addition, the effectiveness of multiple tug assistance in different positions is discussed in some detail.

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