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.

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.

A Numerical Model to Initiate the Icebreaking Pattern in Level Ice

2014 ◽  
Author(s):  
Sandro Erceg ◽  
Sören Ehlers ◽  
Rüdiger von Bock und Polach ◽  
Bernt Leira
Keyword(s):  
Numerical Models ◽  
Numerical Approach ◽  
Interaction Zone ◽  
Ice Loads ◽  
Level Ice ◽  
Semi Empirical ◽  
Model Features ◽  
Radial Cracks ◽  
Increased Activity

Ships navigating in ice-covered waters experience local and global ice loads due to ice-hull interaction. The design of a ship with good ice performance requires adequate assessment of these forces. Recently, an increased activity in developing numerical models of ice-hull interaction in level ice has been observed, owed to the increased computational capabilities. However, certain semi-empirical icebreaking patterns inevitably influencing the interaction process have been implemented in the majority of interaction models used for the assessment of ice performance of ships. Therefore, an attempt using a quasi-static numerical approach to model the initiation of icebreaking pattern in level ice has been made and is presented in this paper. The term initiation herein denotes the creation of circumferential cracks, disregarding thus the succeeding radial cracks. The concept used in the model features a set of radially oriented ice beams at the interaction zone. The model accounts for the bow geometry and the properties of the encountered ice. The icebreaking pattern for a case study ship is simulated using the developed model. Lastly, this paper discusses the sensitivity of the model with respect to the bow shape.

scholarly journals Numerical simulation of ship performance in level ice: A framework and a model

2020 ◽  
Vol 102 ◽  
pp. 102288
Author(s):  
Fang Li ◽  
Floris Goerlandt ◽  
Pentti Kujala
Keyword(s):  
Numerical Simulation ◽  
Level Ice ◽  
Ship Performance

Simultaneous heat and mass transfer during evaporation from a film of liquid into the turbulent gas

1982 ◽  
Vol 47 (3) ◽  
pp. 766-775 ◽  
Author(s):  
Václav Kolář ◽  
Jan Červenka
Keyword(s):  
Experimental Data ◽  
Mass Transfer ◽  
Liquid Film ◽  
Heat And Mass Transfer ◽  
Driving Forces ◽  
Proper Definition ◽  
Definition Of ◽  
Simultaneous Heat ◽  
Theory And Experiment

The paper presents results obtained by processing a series of published experimental data on heat and mass transfer during evaporation of pure liquids from the free board of a liquid film into the turbulent gas phone. The data has been processed on the basis of the earlier theory of mechanism of heat and mass transfer. In spite of the fact that this process exhibits a strong Stefan's flow, the results indicate that with a proper definition of the driving forces the agreement between theory and experiment is very good.

scholarly journals Can one use Earth’s magnetic axial dipole field intensity to predict reversals?

2020 ◽  
Author(s):  
K Gwirtz ◽  
M Morzfeld ◽  
A Fournier ◽  
G Hulot
Keyword(s):  
Magnetic Field ◽  
Numerical Models ◽  
Dipole Field ◽  
Axial Dipole ◽  
Intensity Threshold ◽  
Magnetic Dipole Field ◽  
Model Hierarchy ◽  
Definition Of ◽  
Virtual Axial Dipole Moment ◽  
Prediction Strategy

Summary We study predictions of reversals of Earth’s axial magnetic dipole field that are based solely on the dipole’s intensity. The prediction strategy is, roughly, that once the dipole intensity drops below a threshold, then the field will continue to decrease and a reversal (or a major excursion) will occur. We first present a rigorous definition of an intensity threshold-based prediction strategy and then describe a mathematical and numerical framework to investigate its validity and robustness in view of the data being limited. We apply threshold-based predictions to a hierarchy of numerical models, ranging from simple scalar models to 3D geodynamos. We find that the skill of threshold-based predictions varies across the model hierarchy. The differences in skill can be explained by differences in how reversals occur: if the field decreases towards a reversal slowly (in a sense made precise in this paper), the skill is high, and if the field decreases quickly, the skill is low. Such a property could be used as an additional criterion to identify which models qualify as Earth-like. Applying threshold-based predictions to Virtual Axial Dipole Moment (VADM) paleomagnetic reconstructions (PADM2M and Sint-2000) covering the last two million years, reveals a moderate skill of threshold-based predictions for Earth’s dynamo. Besides all of their limitations, threshold-based predictions suggests that no reversal is to be expected within the next 10 kyr. Most importantly, however, we show that considering an intensity threshold for identifying upcoming reversals is intrinsically limited by the dynamic behavior of Earth’s magnetic field.

scholarly journals An Approach to Determine Optimal Bow Configuration of Polar Ships under Combined Ice and Calm-Water Conditions

2021 ◽  
Vol 9 (6) ◽  
pp. 680
Author(s):  
Hui Li ◽  
Yan Feng ◽  
Muk Chen Ong ◽  
Xin Zhao ◽  
Li Zhou
Keyword(s):  
Numerical Simulation ◽  
Water Resistance ◽  
Numerical Technique ◽  
Experimental Studies ◽  
Resistance Index ◽  
Simulation Method ◽  
Present Approach ◽  
Calm Water ◽  
Level Ice ◽  
Ice Resistance

Selecting an optimal bow configuration is critical to the preliminary design of polar ships. This paper proposes an approach to determine the optimal bow of polar ships based on present numerical simulation and available published experimental studies. Unlike conventional methods, the present approach integrates both ice resistance and calm-water resistance with the navigating time. A numerical simulation method of an icebreaking vessel going straight ahead in level ice is developed using SPH (smoothed particle hydrodynamics) numerical technique of LS-DYNA. The present numerical results for the ice resistance in level ice are in satisfactory agreement with the available published experimental data. The bow configurations with superior icebreaking capability are obtained by analyzing the sensitivities due to the buttock angle γ, the frame angle β and the waterline angle α. The calm-water resistance is calculated using FVM (finite volume method). Finally, an overall resistance index devised from the ship resistance in ice/water weighted by their corresponding weighted navigation time is proposed. The present approach can be used for evaluating the integrated resistance performance of the polar ships operating in both a water route and ice route.

WoCoVA consensus on the clinical use of in-line filtration during intravenous infusions: Current evidence and recommendations for future research

2021 ◽  
pp. 112972982198916
Author(s):  
Ton Van Boxtel ◽  
Mauro Pittiruti ◽  
Annemarie Arkema ◽  
Patrick Ball ◽  
Giovanni Barone ◽  
...  
Keyword(s):  
Potential Benefit ◽  
Scientific Evidence ◽  
Venous Access ◽  
Current Evidence ◽  
Future Research ◽  
Global Awareness ◽  
Current State ◽  
Intravenous Infusions ◽  
Proper Definition ◽  
Definition Of

The need for filtering intravenous infusions has long been recognized in the field of venous access, though hard scientific evidence about the actual indications for in-line filters has been scarce. In the last few years, several papers and a few clinical studies have raised again this issue, suggesting that the time has come for a proper definition of the type of filtration, of its potential benefit, and of its proper indications in clinical practice. The WoCoVA Foundation, whose goal is to increase the global awareness on the risk of intravenous access and on patients’ safety, developed the project of a consensus on intravenous filtration. A panel of experts in different aspects of intravenous infusion was chosen to express the current state of knowledge about filtration and to indicate the direction of future research in this field. The present document reports the final conclusions of the panel.

Numerical Simulation of the Free-Surface Turbulent Flow around a VLCC Ship Hull

2007 ◽  
Author(s):  
Adrian Lungu ◽  
Theodore E. Simos ◽  
George Psihoyios ◽  
Ch. Tsitouras
Keyword(s):  
Numerical Simulation ◽  
Free Surface ◽  
Turbulent Flow ◽  
Ship Hull
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