Subsurface Ice Transport at a Transversally Towed Ship Model

2017 ◽  
Author(s):  
Li Zhou ◽  
Rüdiger U. Franz von Bock und Polach ◽  
Xu Bai
Keyword(s):  
Froude Number ◽  
Densimetric Froude Number ◽  
Ship Model ◽  
Drift Speed ◽  
Ice Accumulation ◽  
Underwater Cameras ◽  
Low Froude Number ◽  
Broken Ice ◽  
Level Ice ◽  
Ice Floes

The subsurface transport of ice along the underwater body of a ship hull or a structure may cause damages to appendages. In order to investigate the conditions under which the ice accumulation occurs, a series of model tests was carried out in the ice basin of Aalto University. The used ship model was towed laterally against the ice with one side breaking level ice. The transport of broken ice floes broken off from the intact ice sheet has been has been monitored with underwater cameras. Both the model drift speed, respectively the ice drift speed, and the ice thickness are found to affect ice accumulation process. The Densimetric Froude number is introduced as measured to determine whether ice floes will accumulate on the upstream of the hull. It is found that ice accumulation is triggered at relatively low Froude number.

Experimental and Theoretical Investigations on the Characteristics of Ice Floes Broken by Ships Sailing Ahead in Level Ice

2019 ◽  
Author(s):  
Daniela Myland
Keyword(s):  
Image Analysis ◽  
Research Effort ◽  
Analysis Procedure ◽  
Shape Parameters ◽  
Ship Model ◽  
Video Frames ◽  
Theoretical Investigations ◽  
Level Ice ◽  
Ice Floes ◽  
Ice Resistance

Abstract Although the hull shapes of modern ice breaking vessels seem to be quite similar at a first glance, there are significant differences in their ice breaking performance. A significant amount of research effort was spent on investigations of the icebreaking process and the resulting forces. However, little information is available on the correlations between ice floe characteristics, hull shape parameters, ice properties and the ice resistance. Thus, systematic model tests in level ice and pre-sawn ice with four icebreaking ship models of one ship type have been conducted to gain new insight on these correlations. During the tests in level ice under water video records have been taken from below the ship model. Video frames have been analyzed by application of a dedicated image analysis procedure which is mainly based on a number of semiautomatic scripts applied in Matlab®. Results of the analysis are presented and discussed within this paper.

Experimental Studies of Sedimentation Basin Dynamics

1977 ◽  
Vol 12 (1) ◽  
pp. 77-90
Author(s):  
J.F. Cordoba-Molina ◽  
P.L. Silveston ◽  
R. R. Hudgins
Keyword(s):  
Dynamic Response ◽  
Froude Number ◽  
Flow Model ◽  
Experimental Studies ◽  
Densimetric Froude Number ◽  
Number Range ◽  
The Real ◽  
Highly Correlated ◽  
Sedimentation Basins ◽  
Simple Flow

Abstract A simple Flow Model is proposed to describe the dynamic response of sedimentation basins. The response predicted by this model is linear as opposed to the real response of the basin which is nonlinear. However, the real response of the basin is highly correlated with its densimetric Froude number, and as a consequence our linear model effectively predicts the response of the basin in a restricted densimetric Froude Number range. Our experiments show that the response of the basin becomes more sluggish and erratic as the densimetric Froude number decreases.

Further Results on Lee Vortices in Low-Froude-Number Flow

1991 ◽  
Vol 48 (19) ◽  
pp. 2204-2211 ◽  
Author(s):  
Richard Rotunno ◽  
Piotr K. Smolarkiewicz
Keyword(s):  
Froude Number ◽  
Low Froude Number ◽  
Number Flow

The Denver Cyclone. Part I: Generation in Low Froude Number Flow

1990 ◽  
Vol 47 (23) ◽  
pp. 2725-2742 ◽  
Author(s):  
N. Andrew Crook ◽  
Terry L. Clark ◽  
Mitchell W. Moncrieff
Keyword(s):  
Froude Number ◽  
Low Froude Number ◽  
Number Flow

Discussion of “Stilling Basin Design for Low Froude Number”

1976 ◽  
Vol 102 (6) ◽  
pp. 797-799
Author(s):  
Heramb D. Sharma ◽  
Dharam V. Varshney
Keyword(s):  
Froude Number ◽  
Stilling Basin ◽  
Low Froude Number

scholarly journals Nose-Angle Bridge Piers as Alternative Countermeasures for Local Scour Reduction

2018 ◽  
Vol 13 (2) ◽  
pp. 110-120 ◽  
Author(s):  
Ibtesam Abudallah Habib ◽  
Wan Hanna Melini Wan Mohtar ◽  
Atef Elsaiad ◽  
Ahmed El-Shafie
Keyword(s):  
Froude Number ◽  
Local Scour ◽  
Bridge Piers ◽  
Scour Depth ◽  
Skew Angle ◽  
Flow Angle ◽  
Sediment Size ◽  
Low Froude Number ◽  
Skew Angles ◽  
Depth Reduction

This study investigates the performance nose-angle piers as countermeasures for local scour reduction around piers. Four nose angles were studied, i.e., 90°, 70°, 60° and 45° and tested in a laboratory. The sediment size was fixed at 0.39 mm whereas the flow angle of attack (or skew angle) was varied at four angles, i.e., skew angles, i.e., 0°, 10°, 20° and 30°. Scour reduction was clear when decreasing nose angles and reached maximum when the nose angle is 45°. Increasing the flow velocity and skew angle was subsequently increasing the scour profile, both in vertical and transversal directions. However, the efficiency of nose angle piers was only high at low Froude number less than 0.40 where higher Froude number gives minimal changes in the maximum scour depth reduction. At a higher skew angle, although showed promising maximum scour depth reduction, the increasing pier projected width resulted in the increase of transversal lengths.

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