A Computational Fluid Dynamics Method for Resistance Prediction of the Floating Hull of Wave Glider

2014 ◽  
Vol 936 ◽  
pp. 2114-2119 ◽  
Author(s):  
Aladdin Elhadad ◽  
Wen Yang Duan ◽  
Rui Deng
Keyword(s):  
Fluid Flow ◽  
Total Resistance ◽  
Numerical Predictions ◽  
Exclusive Economic Zones ◽  
Calm Water ◽  
Wigley Hull ◽  
Wave Glider ◽  
The Cost ◽  
Economic Zones ◽  
Solution Parameters

The wave glider is a surface vehicle with an attached sub-surface wing system which propels the surface component forward, negating the need for a motor. Wave glider could be used for intelligence, surveillance, passive monitoring of marine life, monitoring exclusive economic zones for fishing and other economic resources that are important and useful to coastal countries. Monitoring of coastal waters normally requires large amounts of expensive surveillance. They can be used to find and research resources and fisheries at a fraction of the cost of other methods. Since the wave glider can either be programmed for a journey or to keep station, it is looked at as an alternative for expensive moored buoys. In this paper we present a method focused on the mesh generation to predict calm water resistance for the floating part of the wave glider (the hull). In this study a wigley hull form (4m) used as the floating hull has been investigated in order to predict the fluid flow of the ship using computational fluid dynamics (CFD). Calculations for total resistance are carried out for Froude numbers in the range of 0.10 to 0.40. Commercial CFD software fluent is used to investigate the fluid flow of wigley hull. Three different mesh sizes are used in this study to calculate the mesh effects. The results obtained from CFD calculations for total resistance are compared with the experimental results for accuracy of the solution parameters. The comparison shows a good agreement between experimental and CFD results. The method is evaluated by comparing the numerical predictions for wigley hull form (2m) with wigley hull form (4m) using the same mesh sizes under the same conditions in an attempt to design the floating hull of wave glider . The results obtained from CFD calculations are compared for accuracy of the solution parameters and the method is useful and acceptable.

Comparative Investigation of an Automated Oceanic Wave Surface Glider Robot Influence on Resistance Prediction Using CFD Method

2015 ◽  
Vol 710 ◽  
pp. 91-97
Author(s):  
Aladdin Elhadad ◽  
Wen Yang Duan ◽  
Rui Deng
Keyword(s):  
High Speed ◽  
Water Resistance ◽  
Comparative Investigation ◽  
Numerical Predictions ◽  
Calm Water ◽  
Oceanic Wave ◽  
Computational Fluid Dynamics Cfd ◽  
Wave Glider ◽  
Cfd Method ◽  
Solution Parameters

Thewave glideris composed of two parts: the float is roughly the size and shape of a surfboard that contains all the instrumentation needed for scientific experiments; the sub has wings and hangs 6 meters below on an umbilical tether. This difference allows wave energy to be harvested to produce forward thrust. According to the lake of design information and data for thewave glider, the main aim of the study is usingcomputational fluid dynamics (CFD)to present a method to predict calm water resistance for the floating part of thewave glider(the hull).Wigley parabolic hulland high speed round bilge form (NPL)have been investigated in order to estimate the hydrodynamic performances of the hull usingCFDsoftware fluent.Wave glideris designed with slender hull shapes in order to decrease the wave making resistance of the ship.In this paper a method is evaluated by comparing the numerical predictions forwigleyandNPLforms (2m) using the same mesh generation method under the same conditions to design the hull. Calculations fortotal calm water resistanceare carried out using three different mesh sizes for Froude numbers in the range of 0.10 to 0.40 and compared for accuracy of the solution parameters. The close agreement between the numerical predictions shows the importance ofCFDapplications in estimating the hydrodynamics performance to design the floating hull and the numerical method is useful in glider design. This means that the method discussed in this paper can be used for the resistance calculation of some hulls like the float of the glider.

Numerical Analysis for Resistance Calculations of NPL as a Floating Hull for Wave Glider

2014 ◽  
Vol 619 ◽  
pp. 38-43 ◽  
Author(s):  
Aladdin Elhadad ◽  
Wen Yang Duan ◽  
Rui Deng ◽  
H. Elhanfey
Keyword(s):  
Numerical Analysis ◽  
Mesh Generation ◽  
Numerical Scheme ◽  
Water Resistance ◽  
Numerical Predictions ◽  
Calm Water ◽  
Resistance Prediction ◽  
Wave Glider ◽  
Solution Parameters ◽  
Good Agreement

Thewave glideris an autonomous unmanned vehicle (AUV) which uses the power of the ocean to propel itself. The purpose of this study is using the well known slender modelNPLin developing hull in an attempt to design the floating hull ofwave glider.CFDandMaxsurfsoftware are used to present a method focused on mesh generation to predictcalm water resistancefor the hull. Calculations are carried out for Froude numbers in the range of 0.10 to 0.40. Three different mesh sizes are used forCFDto calculate the mesh effects. The results of numerical predictions under the same conditions obtained fromCFDandMaxsurfcalculations are obtained and compared for accuracy of the solution parameters. The comparison shows a good agreement between the results. The method is useful and acceptable and the overall numerical scheme is suitable for resistance prediction.

scholarly journals Tracking the global reduction of marine traffic during the COVID-19 pandemic

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
David March ◽  
Kristian Metcalfe ◽  
Joaquin Tintoré ◽  
Brendan J. Godley
Keyword(s):  
Large Scale ◽  
Human Mobility ◽  
Western Mediterranean ◽  
Western Mediterranean Sea ◽  
Marine Traffic ◽  
Human Movements ◽  
Exclusive Economic Zones ◽  
Global Impacts ◽  
Economic Zones

AbstractThe COVID-19 pandemic has resulted in unparalleled global impacts on human mobility. In the ocean, ship-based activities are thought to have been impacted due to severe restrictions on human movements and changes in consumption. Here, we quantify and map global change in marine traffic during the first half of 2020. There were decreases in 70.2% of Exclusive Economic Zones but changes varied spatially and temporally in alignment with confinement measures. Global declines peaked in April, with a reduction in traffic occupancy of 1.4% and decreases found across 54.8% of the sampling units. Passenger vessels presented more marked and longer lasting decreases. A regional assessment in the Western Mediterranean Sea gave further insights regarding the pace of recovery and long-term changes. Our approach provides guidance for large-scale monitoring of the progress and potential effects of COVID-19 on vessel traffic that may subsequently influence the blue economy and ocean health.

Autonomous Technology and Dynamic Obligations: Uncrewed Maritime Vehicles and the Regulation of Maritime Military Surveillance in the Exclusive Economic Zone

2021 ◽  
pp. 1-30
Author(s):  
Simon MCKENZIE
Keyword(s):  
Legal Regime ◽  
Coastal State ◽  
Maritime Surveillance ◽  
Legal Obligations ◽  
Legal Implications ◽  
Exclusive Economic Zones ◽  
Dynamic Quality ◽  
Economic Zones ◽  
Environmental Interests ◽  
Autonomous Technology

Abstract The development of uncrewed maritime vehicles [UMVs] has the potential to increase the scale of military maritime surveillance in the exclusive economic zones of foreign coastal states. This paper considers the legal implications of the expanded use of UMVs for this purpose. It shows how features of the legal regime—namely how its application depends on determining the intent of a vessel's operation (to distinguish marine scientific research from military surveillance), as well the obligation to have due regard—have a “dynamic” quality that will pose a challenge to UMVs operated by autonomous technology. The legal obligations will require equipping UMVs with the capacity to communicate something about their identity, the purpose of their mission, and to be able to have some capacity to be responsive to the economic and environmental interests of the coastal state.

Military Activities in the Exclusive Economic Zones of Foreign Coastal States

2012 ◽  
Vol 27 (4) ◽  
pp. 795-803 ◽  
Author(s):  
Moritaka Hayashi
Keyword(s):  
United States ◽  
Exclusive Economic Zone ◽  
Law Of The Sea ◽  
United States Military ◽  
Opposing View ◽  
Coastal State ◽  
Stable Order ◽  
Exclusive Economic Zones ◽  
Economic Zones ◽  
Common Understanding

Abstract One disturbing element in an overall stable order built on the Law of the Sea Convention is the disagreement between some States over the use of the exclusive economic zone (EEZ) of a coastal State by another State for military purposes. While it appears to be generally accepted that military activities in the EEZ of another State are part of “the freedoms . . . of navigation and overflight and other internationally lawful uses of the sea related to these freedoms . . .” under Article 58(1), some States, notably China, hold an opposing view. The disagreement has led to several incidents involving forceful disturbance of activities of United States military vessels and aircraft in and above the EEZ of China. There is an urgent need for the States concerned and the international community to find a common understanding on the issue or some kind of practical arrangement for avoiding further serious incidents.

Differences in foraging habitat result in contrasting fisheries interactions in two albatross populations

2021 ◽  
Vol 663 ◽  
pp. 197-208
Author(s):  
A Corbeau ◽  
J Collet ◽  
A Pajot ◽  
R Joo ◽  
T Thellier ◽  
...  
Keyword(s):  
Habitat Use ◽  
Habitat Specialization ◽  
Encounter Rate ◽  
Automatic Identification ◽  
Identification System ◽  
Diomedea Exulans ◽  
Exclusive Economic Zones ◽  
Males And Females ◽  
Fisheries Interactions ◽  
Economic Zones

Albatrosses attend fishing boats to feed on fishing discards but are often at risk of accidental bycatch. To examine whether populations (same species) and sexes differ in their overlap with fisheries due to differences in habitat use, we combined the use of recently developed loggers equipped with GPS and boat radar detectors with Automatic Identification System (AIS) data. Our study indicates that incubating wandering albatrosses Diomedea exulans from Crozet and Kerguelen foraged in different habitats although the duration of trips was similar. Both female and male Kerguelen birds took advantage of the large and productive surrounding shelf, whereas Crozet birds used the small shelf around the islands to a lesser extent. In Crozet, there was segregation between males and females, the latter favouring deeper and warmer waters. The 2 strategies of habitat use led to different overlap and attraction to boats, with Kerguelen birds encountering and attending boats for longer and at closer proximity to the colony than Crozet birds. Crozet females encountered boats at greater distances from the colony than males. Because of their different habitat use and foraging outside exclusive economic zones (EEZ) and further from the colony, Crozet birds attended more non-declared boats (without AIS) than Kerguelen birds. Albatrosses were more attracted by fisheries than cargo vessels and were especially attracted by fishing discards that led them to attend vessels for longer periods for both sexes and populations. The differences found between populations and individuals in terms of habitat specialization and encounter rate of fisheries should be considered for future assessments of risk of bycatch.

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