Sea spray icing: The physical process, and review of prediction models and winterization techniques

2021 ◽  
pp. 1-26
Author(s):  
Sujay Deshpande ◽  
Ane Sæterdal ◽  
Per-Arne Sundsbø
Keyword(s):  
Prediction Models ◽  
Offshore Structures ◽  
Cold Climate ◽  
Working Environment ◽  
The Arctic ◽  
Design Stage ◽  
Sea Spray ◽  
Ice Accretion ◽  
Sea Wind ◽  
The Impact

Abstract Ice accretion on marine vessels and offshore structures is a severe hazard in the Polar Regions. There is increasing activities related to oil and gas exploration, tourism, cargo transport, and fishing in the Arctic. Ice accretion can cause vessel instability, excess load on marine structures and represents a safety risk for outdoor working environment and operations. Freezing sea spray is the main contributor to marine icing. For safe operations in cold climate, it is essential to have verified models for prediction of icing. Sea spray icing forecast models have improved. Empirical and theoretical models providing icing rates based may be useful as guidelines. For predicting the distribution of icing on a surface at the design stage, Computational Fluid Dynamics has to be applied along with a freezing module. State-of-the-art models for numerical simulation of sea spray icing are still not fully capable of modelling complex ship-sea-wind interactions with spray generation and impact of shipped water. Existing models include good understanding of spray flow effects and freezing. Further development should focus on developing models for dynamic ship-sea-wind interactions, in particular including spray generation, effects of shipped water and distribution of icing on the vessel surface. More experimental and full-scale data is needed for development and verification of new and improved models. Models that estimate ice distribution may improve the winterization design process and reduce effort required for de-icing. Improved methods for de-icing and anti-icing will reduce the impact of sea spray icing and increase safety for marine operations in cold waters.

Practical Structural Assessment of Offshore Structures for Wave Slap

2012 ◽  
Author(s):  
Joong Soo Moon ◽  
Tae Hyun Park ◽  
Woo Seung Sim ◽  
Hyun Soo Shin
Keyword(s):  
Static Pressure ◽  
Impact Load ◽  
Offshore Structures ◽  
Model Tests ◽  
Design Stage ◽  
Load Prediction ◽  
Structural Assessment ◽  
Pressure Impulse ◽  
The Impact ◽  
Design Pressure

By the combination of theoretical and empirical approach, the methodology for practical structural assessment of offshore structures for wave slap is proposed. It is developed for engineers in the sense that the precise design pressure is easily obtainable and quickly applicable in early and detail design stage. For impact load prediction, the Pressure-Impulse theory that was well developed and validated in coastal engineering field is applied. The impact pressures are classified into three types (traditional, sharp, and immersed slap) according to model tests and BP Schiehallion FPSO’s bow monitoring. The time histories of impact pressures for the classified impact types are generated with the pressure impulse predicted by the Pressure-Impulse theory. Nonlinear transient structural analyses are performed using the time series of impact pressures to obtain equivalent static pressure factors. Finally, the design pressure is determined by multiplying the maximum peak pressure by the equivalent static pressure factor. The results are validated through the comparison with model tests and dedicated reports.

Negative changes in permafrost due to waste storage

2020 ◽  
Author(s):  
Valery Grebenets ◽  
Fedor Iurov ◽  
Vasily Tolmanov
Keyword(s):  
Chemical Reactions ◽  
Frozen Soil ◽  
Cold Climate ◽  
The Arctic ◽  
Chemical Pollution ◽  
Drilling Fluids ◽  
Waste Storage ◽  
Frozen State ◽  
The Impact ◽  
Cryogenic Processes

<p>Keywords: permafrost, waste, hazardous cryogenic processes</p><p>The problem of waste storage is particularly acute in Arctic. This is due to the vulnerability of northern ecosystems, the existence of permafrost, especially vulnerable to anthropogenic impact, the water-resistant properties of frozen rocks and the effect of destructive cryogenic processes. In addition, the causes of concern are the trends in air and frozen soil temperatures reported for the northern regions: pollutants stored in relatively stable frozen state can be released into the environment as a result of thawing. This is especially true for industrial regions, where billions of cubic meters of waste from the mining and beneficiation of ores and coal, form timber processing, mine water spills and drilling fluids, etc. are stored in a frozen state.</p><p>Field investigations were carried out in number of settlements in cryolithozone of Russia (Norilsk, Vorkuta, Igarka, settlements in the lower Ob, national villages of Taimyr, etc.). The observations involved remote sensing methods and included estimation of the area of littering and the types of waste. In many cases sampling for chemical analyzes, thermometry, and mapping of hazardous processes were made.</p><p>The impact of stored wastes on permafrost was divided into three main types: a) mechanical (changing the relief and the flow paths of surface and ground waters); b) physical and chemical (pollution by the waste itself and by its decomposition products); c) thermal (heating of frozen soils by high-temperature waste or heat generation during various chemical reactions).</p><p>During the research, 6 main types of waste storage were identified, each of which had a destructive effect on permafrost soils and northern ecosystems:</p><p>1) dumps of municipal solid waste (inherent in all settlements);</p><p>2) storages of industrial waste, tailing storage facilities in the industrial centers of the north;</p><p>3) abandoned and cluttered territories;</p><p>4) landfills of timber processing waste in the centers of the timber industry;</p><p>5) rock dumps in open-cast mining sites, which in the cold climate can transform into rock glaciers;</p><p>6) storage areas for polluted snow tranfered from built-up areas.</p><p>Particular attention was paid to the accumulation of chemical pollutants in industrial centers (with Norilsk industrial region as an example). This problem in conditions of permafrost is exacerbated by the low self-purification of northern biogeocenoses; slowdown of oxidation and some other chemical reactions in cold climates; drainage and unloading of groundwater of seasonally thawed layer, intra-permafrost and under-permafrost taliks into the water bodies.</p><p>The use of imperfect technologies for the extraction and processing the raw materials, remains of past years practices with neglected environmental situation, the lack of special standards for the storage of waste and industrial by-products, the lack of development of waste disposal methods for severe climatic conditions led to the pollution of vast territories and to destruction of many ecosystems.</p><p>This work was supported by the RFBR grant 18-05-60080 “Dangerous nival-glacial and cryogenic processes and their impact on infrastructure in the Arctic”.</p>

Predicted Ice Accretion on Horizontal Surfaces of Marine Vessels and Offshore Structures in Arctic Regions

2016 ◽  
Author(s):  
Alireza Dehghani-Sanij ◽  
Yuri S. Muzychka ◽  
Greg F. Naterer
Keyword(s):  
Water Film ◽  
Theoretical Method ◽  
Offshore Structures ◽  
Sea Spray ◽  
Ice Accretion ◽  
Wave Direction ◽  
Arctic Regions ◽  
Air Temperatures ◽  
The Stability ◽  
Marine Vessels

Sea spray icing is one of the most significant problems for the operation of marine vessels and offshore structures in Arctic regions. This phenomenon affects the stability of marine vessels and offshore structures, and also the safety of human activities onboard. In this paper, a new predictive icing model for large horizontal surfaces of a marine vessel is developed. To obtain the total flux of sea spray during the icing process, both wind spray and wave spray are considered. By applying heat, mass and salt concentration balances, the freezing fraction, temperature distribution, ice layer and water film thicknesses are determined. Moreover, the effects of different parameters on the freezing fractions at various air temperatures are investigated. The results indicate that air temperature, wind velocity, vessel speed, spray water salinity, height from the water surface, and angle between the vessel heading and wind/wave direction are major parameters in the growth rate of the ice. This theoretical method provides a reasonably accurate and simple way for predicting the sea spray icing phenomena on marine vessels and offshore structures.

The Fracture Resistance Approach in Order to Prevent Brittle Failure of Offshore Structures Under Arctic Environments

2016 ◽  
Author(s):  
Agnes Marie Horn ◽  
Erling Østby ◽  
Per Olav Moslet ◽  
Mons Hauge
Keyword(s):  
Brittle Failure ◽  
Structural Integrity ◽  
Early Stage ◽  
Steel Structures ◽  
Offshore Structures ◽  
The Arctic ◽  
Design Stage ◽  
Main Question ◽  
Overall Design ◽  
Offshore Industry

This paper is concerned with the challenges related to steel design under Arctic conditions where both loading and temperature have been discussed in relation to material requirements. Today there is a lack of rules and standards for selecting steel materials for bulk engineering for a lower design temperature than −10°C (NORSOK N-004 [1] allows down to −14°C). Both ISO 19902 Steel Structures [2] and NORSOK N-004 Design of steel structures make reference to EN10225 “Weldable structural steels for fixed offshore structures technical delivery conditions [5]” where steel materials are Charpy tested at a lowest test temperature of −40°C and proven for a design of −10°C. Hence, one major challenge for designers are to specify adequate toughness requirements at an early stage of the design process for low temperature applications. Both NORSOK N-004[1] and ISO 19902[2] provide requirements to load combinations that need to be fulfilled, however the relationship between various load types and temperature is not mentioned in any of these standards. Thus, in the design stage the material needs to demonstrate adequate toughness where loading and temperature are treated independently. For the offshore industry, the main question is the balance between materials requirements and cost-effective solutions, and how to address this within an overall design perspective in order to avoid brittle failure. This paper discusses some of these challenges with the aim of starting a focused process leading up to a clear interpretation of the implications of overall design philosophies, necessary in order to define consistent materials requirements ensuring that brittle fracture is not going to represent a significant threat to the structural integrity. The material recommendations provided in the paper are based on the latest research results from the Arctic Materials project (2008–2017) managed by SINTEF and supported by the industry.

Impact of Orbital Parameters and Greenhouse Gas on the Climate of MIS 7 and MIS 5 Glacial Inceptions

2014 ◽  
Vol 27 (23) ◽  
pp. 8918-8933 ◽  
Author(s):  
Florence Colleoni ◽  
Simona Masina ◽  
Annalisa Cherchi ◽  
Doroteaciro Iovino
Keyword(s):  
Greenhouse Gas ◽  
General Circulation ◽  
Regional Scale ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Cold Climate ◽  
The Arctic ◽  
Orbital Parameters ◽  
The Impact ◽  
Mis 5

Abstract This work explores the impact of orbital parameters and greenhouse gas concentrations on the climate of marine isotope stage (MIS) 7 glacial inception and compares it to that of MIS 5. The authors use a coupled atmosphere–ocean general circulation model to simulate the mean climate state of six time slices at 115, 122, 125, 229, 236, and 239 kyr, representative of a climate evolution from interglacial to glacial inception conditions. The simulations are designed to separate the effects of orbital parameters from those of greenhouse gas (GHG). Their results show that, in all the time slices considered, MIS 7 boreal lands mean annual climate is colder than the MIS 5 one. This difference is explained at 70% by the impact of the MIS 7 GHG. While the impact of GHG over Northern Hemisphere is homogeneous, the difference in temperature between MIS 7 and MIS 5 due to orbital parameters differs regionally and is linked with the Arctic Oscillation. The perennial snow cover is larger in all the MIS 7 experiments compared to MIS 5, as a result of MIS 7 orbital parameters, strengthened by GHG. At regional scale, Eurasia exhibits the strongest response to MIS 7 cold climate with a perennial snow area 3 times larger than in MIS 5 experiments. This suggests that MIS 7 glacial inception is more favorable over this area than over North America. Furthermore, at 239 kyr, the perennial snow covers an area equivalent to that of MIS 5 glacial inception (115 kyr). The authors suggest that MIS 7 glacial inception is more extensive than MIS 5 glacial inception over the high latitudes.

scholarly journals Plant Sedimentary Ancient DNA From Far East Russia Covering the Last 28,000 Years Reveals Different Assembly Rules in Cold and Warm Climates

2021 ◽  
Vol 9 ◽  
Author(s):  
Sichao Huang ◽  
Kathleen R. Stoof-Leichsenring ◽  
Sisi Liu ◽  
Jeremy Courtin ◽  
Andrej A. Andreev ◽  
...  
Keyword(s):  
Ancient Dna ◽  
Genetic Divergence ◽  
Far East ◽  
Cold Climate ◽  
The Arctic ◽  
Assembly Rules ◽  
Number Of Species ◽  
Shrub Tundra ◽  
Plant Assemblages ◽  
The Impact

Woody plants are expanding into the Arctic in response to the warming climate. The impact on arctic plant communities is not well understood due to the limited knowledge about plant assembly rules. Records of past plant diversity over long time series are rare. Here, we applied sedimentary ancient DNA metabarcoding targeting the P6 loop of the chloroplast trnL gene to a sediment record from Lake Ilirney (central Chukotka, Far Eastern Russia) covering the last 28 thousand years. Our results show that forb-rich steppe-tundra and dwarf-shrub tundra dominated during the cold climate before 14 ka, while deciduous erect-shrub tundra was abundant during the warm period since 14 ka. Larix invasion during the late Holocene substantially lagged behind the likely warmest period between 10 and 6 ka, where the vegetation biomass could be highest. We reveal highest richness during 28–23 ka and a second richness peak during 13–9 ka, with both periods being accompanied by low relative abundance of shrubs. During the cold period before 14 ka, rich plant assemblages were phylogenetically clustered, suggesting low genetic divergence in the assemblages despite the great number of species. This probably originates from environmental filtering along with niche differentiation due to limited resources under harsh environmental conditions. In contrast, during the warmer period after 14 ka, rich plant assemblages were phylogenetically overdispersed. This results from a high number of species which were found to harbor high genetic divergence, likely originating from an erratic recruitment process in the course of warming. Some of our evidence may be of relevance for inferring future arctic plant assembly rules and diversity changes. By analogy to the past, we expect a lagged response of tree invasion. Plant richness might overshoot in the short term; in the long-term, however, the ongoing expansion of deciduous shrubs will eventually result in a phylogenetically more diverse community.

Explosion Safety Drivers for Arctic Platform Designs

2012 ◽  
Author(s):  
Joar Dalheim ◽  
Sverre Nodland ◽  
Jan Pappas
Keyword(s):  
Safety Issue ◽  
Arctic Region ◽  
Cold Climate ◽  
Working Environment ◽  
The Arctic ◽  
Process Equipment ◽  
Main Process ◽  
Explosion Safety ◽  
Mechanically Ventilated ◽  
Explosion Risk

The unique and harsh environment of the arctic region requires specialized process area designs and safety solutions. One main process safety issue in the arctic is the need for more enclosed modules. Enclosed modules are used for two reasons; to prevent ice and snow to expose the process equipment; and to prevent the cold climate to impose an unduly harsh working environment for operators. The enclosed mechanically ventilated process modules are different from the open naturally ventilated process modules that are normally used in offshore facilities. The explosion safety performance of the non-standard mechanically ventilated process modules has therefore been studied in detail through several extensive programs of CFD simulations; see [1], [2] and [3]. It is seen that confined and mechanically ventilated modules has explosion risk drivers that are distinctly different from open and naturally ventilated modules. The following is seen to have significant impact on the explosion risk levels on confined process modules; the module size; the HVAC philosophy; the ignition source isolation efficiency; and the use of pressure release panels. These factors, and their impact on the explosion risk, are discussed in this paper. The presented conclusions are of high importance in future developments in arctic climate.

scholarly journals Numerical analysis of impact pressures on board during vessel movement in ice

2020 ◽  
Author(s):  
В.Г. Бугаев ◽  
В.В. Новиков ◽  
К.А. Молоков ◽  
Д.В. Славгородская
Keyword(s):  
Method Comparison ◽  
The Body ◽  
The Arctic ◽  
Design Stage ◽  
Shock Pulse ◽  
Good Convergence ◽  
The Many ◽  
Comparison Of The Results ◽  
The Impact ◽  
Contact Pressures

Вопросам прочности судов при эксплуатации во льдах в последнее время уделяется все больше внимания в связи возрастающим интересом к освоению Арктики. Несмотря на множество проведенных исследований, остаются не всегда ясными и трудно определимыми величина и характер ударных контактных давлений на корпус, что связано со сложным процессом соударения льда и корабля, зависящим от многочисленных факторов. В этой связи, важным является накопление и систематизация результатов исследований. В данной работе проведен расчетный анализ ударного воздействия льда на корпус ледокола, показано, как изменяются амплитуда, длительность и форма ударного импульса. Выполнена оценка напряжений, перемещений и деформаций, возникающих в процессе смятия и изгиба ледовой пластины, контактных давлений в зависимости от скорости соударения, массы, толщины и конфигурации льдины, а также от углов наклона борта к вертикали и ватерлинии к диаметральной плоскости. Исследование проведено при рассмотрении процесса удара на 3D-модели корпуса и аналитическим методом. Сравнение результатов анализа численного моделирования и аналитических расчетов показывают достаточно хорошую их сходимость. Картина взаимодействия корпуса судна со льдом, а также численные значения параметров (ударного импульса, состояния льда) свидетельствуют о пригодности нелинейного динамического исследования на этапе проектирования и инженерного анализа формы корпуса судна. Полученные данные о количественном влиянии рассмотренных параметров на интенсивность ударного давления могут быть учтены при разработке судовой поверхности ледокольных судов на начальной стадии проектирования, а также при составлении ледовых паспортов. Recently, more and more attention has been paid to the issues of ship durability during operation in ice due to the growing interest in the development of the Arctic. Despite the many studies performed, the magnitude and nature of impact contact pressures on the hull are not always clear and difficult to determine, which is associated with the complex process of collision of ice and the ship, depending on numerous factors. In this regard, the accumulation and systematization of research results is important. In this work, we performed a calculation analysis of the impact of ice on the icebreaker’s hull, showing how the amplitude, duration and shape of the shock pulse change. The stresses, displacements, and deformations arising during the crushing and bending of the ice plate, the contact pressures depending on the impact speed, mass, thickness and configuration of the ice floe, as well as on the angles of inclination of the bead to the vertical and the waterline to the diametrical plane, were estimated. The study was conducted when considering the impact process on a 3D model of the body and the analytical method. Comparison of the results of the analysis of numerical simulation and analytical calculations show a fairly good convergence. The picture of the interaction of the ship’s hull with ice, as well as the numerical values of the parameters (shock pulse, ice state) indicate the suitability of nonlinear dynamic research at the stage of design and engineering analysis of the shape of the ship’s hull. The obtained data on the quantitative influence of the considered parameters on the pressure intensity can be taken into account when developing the ship surface of icebreaking vessels at the initial design stage, as well as when compiling ice certificates.

scholarly journals Sea Spray Generation at a Rocky Shoreline

2016 ◽  
Vol 55 (9) ◽  
pp. 2037-2052 ◽  
Author(s):  
Edgar L Andreas
Keyword(s):  
Wind Speed ◽  
Surf Zone ◽  
Open Water ◽  
High Energy ◽  
Offshore Structures ◽  
The Arctic ◽  
Sea Spray ◽  
Near Surface ◽  
Marginal Seas ◽  
Wind Speeds

AbstractWith sea ice in the Arctic continuing to shrink, the Arctic Ocean and the surrounding marginal seas will become more like the ocean at lower latitudes. In particular, with more open water, air–sea exchange will be more intense and storms will be stronger and more frequent. The longer fetches over open water and the more energetic storms will combine to produce higher waves and more sea spray. Offshore structures—such as oil drilling, exploration, and production platforms—will face increased hazards from freezing sea spray. On the basis of sea spray observations made with a cloud-imaging probe at Mount Desert Rock (an island off the coast of Maine), the spray that artificial islands built in the Arctic might experience is quantified. Mount Desert Rock is small, low, and unvegetated and has an abrupt, rocky shoreline like these artificial islands might have. Many of the observations were at air temperatures below freezing. This paper reports the near-surface spray concentration and the rate of spray production at this rocky shoreline for spray droplets with radii from 6.25 to 143.75 μm and for wind speeds from 5 to 17 m s−1. Spray concentration increases as the cube of the wind speed, but the shape of the concentration spectrum with respect to radius does not change with wind speed. Both near-surface spray concentration and the spray-production rate are three orders of magnitude higher at this rocky shoreline than over the open ocean because of the high energy and resulting continuous white water in the surf zone.

Improved Structural Integrity for Arctic Designs by Ignition Isolation Control

2011 ◽  
Author(s):  
Joar Dalheim ◽  
Sverre Nodland ◽  
Jan Pappas
Keyword(s):  
Structural Integrity ◽  
Safety Issue ◽  
Cold Climate ◽  
Working Environment ◽  
Ignition Source ◽  
The Arctic ◽  
Process Equipment ◽  
Mechanically Ventilated ◽  
Design Loads ◽  
Extensive Program

The harsh environment of the arctic requires specialized safety solutions. One main safety issue in the arctic is the need for more enclosed modules. Enclosed modules are used for two reasons; to prevent ice and snow to expose the process equipment; and to prevent the cold climate to impose an unduly harsh working environment for operators. The enclosed mechanically ventilated process modules are different from the open naturally ventilated process modules that are normally used in offshore facilities. The explosion safety performance of the non-standard mechanically ventilated process modules has therefore been studied in detail through an extensive program of CFD simulations. It is seen that mechanically ventilated modules has explosion risk drivers that are distinctly different from risk drivers in naturally ventilated modules. It is seen that the ignition source isolation efficiency is significantly more important for confined modules than for standard naturally ventilated modules. The explosion design loads are therefore strongly depending on the ignition source isolation efficiency. Isolation control, and its impact on the explosion design loads, is discussed in this paper. The presented conclusions are of high importance in future developments in arctic climate.

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