Ice Block Research Articles

Initiation of ice jam in front of bridge piers—An experimental study

The presence of bridge piers in natural rivers significantly changes the flow and boundary conditions. As a consequence, ice jams can often be initiated in front of bridge piers. With the changes in flow conditions, two types of ice jam formation may appear: surface accumulation of ice blocks (surface ice blockage) and thickened accumulation of ice blocks (vertical ice blockage). In the present study, the initiation process of ice jam was studied based on experiments. It is found that the critical ice concentration for ice jam blockage depends on the ice block dimension, channel opening and flow conditions. Under surface blockage conditions, a larger ratio of ice cube dimension to channel opening (between piers) can result in a smaller critical ice concentration for ice jam blockage, which has no obvious relation with flow conditions. Under vertical blockage conditions, the critical ice concentration for ice jam blockage increases with flow Froude number and decreases with the ratio of ice dimension to channel opening (between piers). Based on experiments conducted in laboratory, equations for determining critical ice concentration for these two types of ice jam blockage have been developed.

Experimental methods for ultrasonic testing of complex-shaped parts encased in ice

Detection of damage in safety-critical components with complex geometry represents a long-standing challenge in NDE. The ultrasonic inspection of these parts in immersion is often not feasible due to the large impedance and velocity contrast between water and metals which can severely limit the penetration of the ultrasonic signal inside the part. However, this contrast can be significantly reduced if the water is frozen prior to the inspection leading to what has been referred to as Cryoultrasonic NDE. Since the speed of longitudinal waves in ice is more than 2.5 times greater than the speed in water, ice can be an ideal solid couplant provided that it is devoid of bubbles and cracks and that it is fully bonded to the surface of the part. This paper introduces new experimental methods to encase complex parts in blocks of crystal clear ice and presents the first low temperature scanner for ultrasonic array testing of ice-encapsulated parts. It is shown that by controlling the propagation of the solidification front while water is freezing, it is possible to prevent the formation of cracks inside the ice volume. On the other hand, bubble nucleation can be avoided by continuously forcing water circulation on the solidification front. An analytical model is provided to describe the propagation of the front and predict freezing times. Moreover, high-frequency ultrasonic monitoring experiments confirm the excellent adhesion strength properties of ice to metals. Finally, experiments performed with an additively manufactured Ti6Al4V impeller demonstrate the feasibility of performing low temperature array contact scans on the surface of the ice block encasing the part.

Development of an Ice Jam Flood Forecasting System for the Lower Oder River—Requirements for Real-Time Predictions of Water, Ice and Sediment Transport

Despite ubiquitous warming, the lower Oder River typically freezes over almost every year. Ice jams may occur during freeze-up and ice cover breakup phases, particularly in the middle and lower reaches of the river, with weirs and piers. The slush ice and ice blocks may accumulate to form ice jams, leading to backwater effects and substantial water level rise. The small bottom slope of the lower Oder and the tidal backflow from the Baltic Sea enhance the formation of ice jams during cold weather conditions, jeopardizing the dikes. Therefore, development of an ice jam flood forecasting system for the Oder River is much needed. This commentary presents selected results from an international workshop that took place in Wrocław (Poland) on 26–27 November 2018 that brought together an international team of experts to explore the requirements and research opportunities in the field of ice jam flood forecasting and risk assessment for the Oder River section along the German–Polish border. The workshop launched a platform for collaboration amongst Canadian, German and Polish scientists, government officials and water managers to pave a way forward for joint research focused on achieving the long-term goal of forecasting, assessing and mitigating ice jam impacts along the lower Oder. German and Polish government agencies are in need of new tools to forecast ice jams and assess their subsequent consequences and risks to communities and ship navigation along a river. Addressing these issues will also help research and ice flood management in a Canadian context. A research program would aim to develop a modelling system by addressing fundamental issues that impede the prediction of ice jam events and their consequences in cold regions.

Проявление автоволн пластического течения в пресном льду при микроволновых измерениях

AbstractResults of measurements of the coefficient of microwave reflection from a block of freshwater ice subjected to plastic deformation are presented. Strong fluctuations in the phase of reflection coefficient are revealed, with the extremum at an electromagnetic radiation wavelength of 1.35 cm. This wavelength corresponds to the region of localized plastic flow autowaves in crystalline media.

Hyperbolicity of the heat equation

In this manuscript, a comparison between the parabolic and hyperbolic partial differential equations for heat diffusion is studied. First, numerical results and an eigenvalue analysis for these two types of equations are shown, which help to understand the difference in the system dynamics. Then, both equations are also considered in a Stefan problem for the melting of an ice block in a one-dimensional setting. The results show that the hyperbolic partial differential equation shows a finite speed of propagation of heat and can represent the system as properly as the parabolic equation.

High-throughput sequencing of fungal communities across the perennial ice block of Scărișoara Ice Cave

ABSTRACTThis survey presents the first high-throughput characterisation of fungal distribution based on ITS2 Illumina sequencing of uncultured microbiome from a 1500 years old perennial ice deposit in Scărișoara Ice Cave, Romania. Of the total of 1 751 957 ITS2 sequences, 64% corresponded to 182 fungal operational taxonomic units, showing a low diversity, particularly in older ice strata, and a distinct temporal distribution pattern. Ascomycota was the major phylum in all ice samples, dominating the 400 and 1500 years old ice strata deposited during the cold Little Ice Age (LIA) and Dark Ages Cold Period, while Basidiomycota was mostly present in 900-years old ice formed during the Medieval Warm Period (MWP). Chytridiomycota and Mucoromycota phyla were present in recently formed and 400-years old ice, respectively. Among the 80 identified genera,Cryptococcus victoriae, commonly found in glacial habitats, was identified in all strata. A positive correlation between fungal distribution and ice conductivity, Ca, Na and Sr concentrations was observed across the ice block, with pH values trailing climate variations during LIA and MWP, respectively. Our record highlighted the presence of a complex climate and environmental-driven fungal community in perennial ice strata accumulated during the last 1500 years in Scărișoara Ice Cave.

A rockfall-induced glacial lake outburst flood, Upper Barun Valley, Nepal

On April 20, 2017, a flood from the Barun River, Makalu-Barun National Park, eastern Nepal formed a 2–3-km-long lake at its confluence with the Arun River as a result of blockage by debris. Although the lake drained spontaneously the next day, it caused nationwide concern and triggered emergency responses. We identified the primary flood trigger as a massive rockfall from the northwest face of Saldim Peak (6388 m) which fell approximately 570 m down to the unnamed glacier above Langmale glacial lake, causing a massive dust cloud and hurricane-force winds. The impact also precipitated an avalanche, carrying blocks of rock and ice up to 5 m in diameter that plummeted a further 630 m down into Langmale glacial lake, triggering a glacial lake outburst flood (GLOF). The flood carved steep canyons, scoured the river’s riparian zone free of vegetation, and deposited sediment, debris, and boulders throughout much of the river channel from the settlement of Langmale to the settlement of Yangle Kharka about 6.5 km downstream. Peak discharge was estimated at 4400 ± 1800 m3 s−1, and total flood volume was estimated at 1.3 × 106 m3 of water. This study highlights the importance of conducting integrated field studies of recent catastrophic events as soon as possible after they occur, in order to best understand the complexity of their triggering mechanisms, resultant impacts, and risk reduction management options.

The internal structure of the Brunt Ice Shelf from ice-penetrating radar analysis and implications for ice shelf fracture

Abstract. The rate and direction of rift propagation through ice shelves depend on both the stress field and the heterogeneity (or otherwise) of the physical properties of the ice. The Brunt Ice Shelf in Antarctica has recently developed new rifts, which are being actively monitored as they lengthen and interact with the internal structure of the ice shelf. Here we present the results of a ground-penetrating radar survey of the Brunt Ice Shelf aimed at understanding variations in the internal structure. We find that there are flow bands composed mostly of thick (ca. 250 m) meteoric ice interspersed with thinner (ca. 150 m) sections of ice shelf that have a large proportion of sea ice and seawater-saturated firn. Therefore the ice shelf is, in essence, a series of ice tongues cemented together with ice mélange. The changes in structure are related both to the thickness and flow speed of ice at the grounding line and to subsequent processes of firn accumulation and brine infiltration as the ice shelf flows towards the calving front. It is shown that rifts propagating through the Brunt Ice Shelf preferentially skirt the edges of blocks of meteoric ice and slow their rate of propagation when forced by the stress field to break through them, in contrast to the situation on other ice shelves where rift propagation speeds up in meteoric ice.

Bacterial and archaeal community structures in perennial cave ice

Ice entrenched microcosm represents a vast reservoir of novel species and a proxy for past climate reconstitution. Among glacial ecosystems, ice caves represent one of the scarcely investigated frozen habitats. To characterize the microbial diversity of perennial ice from karst ecosystems, Roche 454 sequencing of 16S rRNA gene amplicons from the underground ice block of Scarisoara Ice Cave (Romania) was applied. The temporal distribution of bacterial and archaeal community structures from newly formed, 400, and 900 years old ice layers was surveyed and analyzed in relation with the age and geochemical composition of the ice substrate. The microbial content of cave ice layers varied from 3.3 104 up to 7.5 105 cells mL−1, with 59–78% viability. Pyrosequencing generated 273,102 reads for the five triplicate ice samples, which corresponded to 3,464 operational taxonomic units (OTUs). The distribution of the bacterial phyla in the perennial cave ice varied with age, organic content, and light exposure. Proteobacteria dominated the 1 and 900 years old organic rich ice deposits, while Actinobacteria was mostly found in 900 years old ice strata, and Firmicutes was best represented in 400 years old ice. Cyanobacteria and Chlorobi representatives were identified mainly from the ice block surface samples exposed to sunlight. Archaea was observed only in older ice strata, with a high incidence of Crenarchaeota and Thaumarchaeaota in the 400 years old ice, while Euryarchaeota dominated the 900 years old ice layers, with Methanomicrobia representing the predominant taxa. A large percentage (55.7%) of 16S rRNA gene amplicons corresponded to unidentified OTUs at genus or higher taxa levels, suggesting a greater undiscovered bacterial diversity in this glacial underground habitat. The prokaryotes distribution across the cave ice block revealed the presence of 99 phylotypes specific for different ice layers, in addition to the shared microbial community. Ice geochemistry represented an important factor that explained the microbial taxa distribution in the cave ice block, while the total organic carbon content had a direct impact on the cell density of the ice microcosm. Both bacterial and archaeal community structures appeared to be affected by climate variations during the ice formation, highlighting the cave ice microbiome as a source of putative paleoclimatic biomarkers. This report constitutes the first high-throughput sequencing study of the cave ice microbiome and its distribution across the perennial underground glacier of an alpine ice cave.

Age Estimates on the Deposition of the Cave Ice Block in the Saarhalle Dachstein-Mammoth Cave (Mammuthöhle, Austria) based on 3H and 14C

ABSTRACTMeasurements of the radiocarbon (14C) and tritium (3H) activity in a 5.8-m-long ice core from the Saarhalle, Dachstein-Mammoth Cave allowed a substantial revision of previous opinions concerning the age of the ice block, and provide useful experience that may be applied to future 14C dating of cave ice deposits. The stepped combustion technique results in a remarkably older radiocarbon age for the 800°C than for the 400°C fractions of the carbonaceous matter from ice layer samples. The highest tritium activity (37.2±1.2 TU) can be linked to the period of anthropogenically increased tritium activity of atmospheric precipitation at the mid-1960s, providing a well-dated radiochemical reference horizon. Compared the 3H-based extrapolated ages of two shallow samples to the expected atmospheric signal an average 14C reservoir bias of ~1500 BP was obtained for the insoluble organic fraction combusted at 400°C. The conventional 14C age measured for the 400°C fraction of the deeper samples has been corrected with the average reservoir bias. The median calibrated age of the deepest analyzed sample of the ice profile is ~1830 cal BC and a linear extrapolation to the bottom ice layer gave 2590 cal BC, making the Saarhalle ice block among the oldest dated cave ice deposits known in the Alpine domain.

A review of discrete element simulation of ice-structure interaction.

Sea ice loads on marine structures are caused by the failure process of ice against the structure. The failure process is affected by both the structure and the ice, thus is called ice–structure interaction. Many ice failure processes, including ice failure against inclined or vertical offshore structures, are composed of large numbers of discrete failure events which lead to the formation of piles of ice blocks. Such failure processes have been successfully studied by using the discrete element method (DEM). In addition, ice appears in nature often as discrete floes; either as single floes, ice floe fields or as parts of ridges. DEM has also been successfully applied to study the formation and deformation of these ice features, and the interactions of ships and structures with them. This paper gives a review of the use of DEM in studying ice–structure interaction, with emphasis on the lessons learned about the behaviour of sea ice as a discontinuous medium.This article is part of the theme issue ‘Modelling of sea-ice phenomena’.

Morphology, internal structure and formation of ice ridges in the sea around Svalbard

The results from 3 years of comprehensive field investigations on first-year ice ridges in the Arctic are presented in this paper. The scopes of these investigations were to fill existing knowledge gaps on ice ridges, gain understanding on ridge characteristics and study internal properties of ice. The ability of developing reliable simulations and load predictions for ridge-structure interactions is the final principal purpose, but beyond the scope of this paper. The presented data comprise ridge geometry, ice block dimensions from ridge sails, ice structure in the ridge and values on the ridge porosity and the degree of consolidation. The total ridge thickness conformed to other ridges studied in the same regions. The consolidated layer thickness was on average 2–3 times the level ice thickness. Minimum 33% and in average 90% of the ridge keel area was consolidated. The distribution of ice block sizes and block shapes within a ridge appears to be predictable. A new approach for deriving a possible ridging scenario and ridge age is presented. Different steps of the ridge building process were identified, which are in good agreement with earlier simulated ridging events. After formation of very thin lead ice between two floes deformation occurs through rafting and ridging until closure of the lead. Subsequently the adjacent level ice floe fractures proceeding ridge formation until ridging forces exceed driving forces. A time span of 10 days could be assessed for a possible ridge formation date, estimating the ridge age of the studied ridge located east of Edgeøya at 78° N to be 7 to 8 weeks.

Numerical simulation of propeller exciting force induced by milling-shape ice

On the basis of the Computational Fluid Dynamics technique (CFD) combined with the overlap grid method, this paper establishes a numerical simulation method to study the problem of ice-propeller interaction in viscous flow and carries out a simulation forecast of the hydrodynamic performance of an ice-class propeller and flow characteristics when in the proximity of milling-shape ice (i.e., an ice block with a groove cut by a high-speed revolving propeller). We use a trimmed mesh in the entire calculation domain and use the overlap grid method to transfer information between the domains of propeller rotation calculation and ice-surface computing. The grid is refined in the narrow gap between the ice and propeller to ensure the accuracy of the flow field. Comparison with the results of the experiment reveals that the error of the hydrodynamic performance is within 5%. This confirms the feasibility of the calculation method. In this paper, we calculate the exciting force of the propeller, analyze the time domain of the exciting force, and obtain the curve of the frequency domain using a Fourier transform of the time-domain curve of the exciting force. The existence of milling-shape ice before the propeller can greatly disturb the wake flow field. Unlike in open water, the propeller bearing capacity shows a downward trend in three stages, and fluctuating pressure is more disordered near the ice.

Unexpected Rise of Glass Transition Temperature of Ice Crystallized from Antifreeze Protein Solution.

Antifreeze protein (AFP) is known to bind to a single ice crystal composed of hexagonally arranged waters, hexagonal ice. To investigate the effect of the AFP binding to a general ice block that is an assembly of numerous hexagonal ice crystals, thermodynamic properties, dynamics, and the crystal structure of the ice block were examined in the presence of type I AFP (AFP-I). Previously, it was found that hexagonal ice has a glass transition based on the proton ordering in the ice lattice at low temperature. Measurements of heat capacity under adiabatic conditions, dielectric permittivity, and powder X-ray diffraction revealed that the glass transition occurs around 140 K in the ice containing 0.01-1% (w/w) of the AFP-I, which is greater than the value for the pure hexagonal ice (ca. 110 K). These data imply that AFP affects the glass transition kinetics, i.e., the slowness of the proton migration in the ice block. Hence, adsorption of AFP molecules to each hexagonal ice is thought to change the physicochemical properties of the bulk ice.

Experimental study on the wake fields of a ship attached with model ice based on stereo particle image velocimetry

In this study, a 76000 DWT 1B ice-class Panamax Bulker attached with model ice was used as a test system for measuring the nominal wake fields based on underwater stereo particle image velocimetry. The results show that: The attached ice block adds a “virtual thickness” to the ship's stern that is equal to the thickness of the ice blocks. The interferes between ice blocks and ship's wake field results in significant expansions of the ship's axial velocity contours compared with the ice-free state, which also leads to the formation of severe velocity blockage zones (with u/U < 0.1) within the wake field against the incident flows of the propeller. The attachment of model ice to hull leads to interference in the stern's wake fields, and disrupts the streamlined in the vicinity of the hull. Furthermore, the non-streamlined shape of the model ice generates complex vortices that interfered with the bilge vortices of the bare hull. The level of interference varies according to the size and distribution of the model ice attachments, and the bilge vortices tends to weaken or shift outwards. Then, the test data were corrected based on momentum theory to be more close to the real phenomena.

Fungi in perennial ice from Sc\u0103ri\u0219oara Ice Cave (Romania)

Screening of 1,000-years old ice layers from the perennial ice block of Scărișoara Ice Cave (NW Romania) revealed the presence of fungal communities. Using culture-dependent methods and molecular techniques based on DGGE fingerprinting of 18S rRNA gene fragments and sequencing, we identified 50 cultured and 14 uncultured fungi in presently-forming, 400 and 900 years old ice layers, corresponding to 28 distinct operational taxonomic units (OTUs). The dominant ice-contained fungal OTUs were related to Ascomycota, Basidiomycota and Cryptomycota phyla. Representatives of Mucoromycota and Chytridiomycota were also isolated from recent and 400 years old ice samples. The cryophilic Mrakia stokesii was the most abundant fungal species found in the cave ice samples of all prospected ages, alongside other cryophilic fungi also identified in various glacial environments. Ice deposits formed during the Little Ice Age (dated between AD 1,250 and 1,850) appeared to have a higher fungal diversity than the ice layer formed during the Medieval Warm Period (prior to AD 1,250). A more complex fungal community adapted to low temperatures was obtained from all analyzed ice layers when cultivated at 4 °C as compared to 15 °C, suggesting the dominance of cold-adapted fungi in this glacial habitat. The fungal distribution in the analyzed cave ice layers revealed the presence of unique OTUs in different aged-formed ice deposits, as a first hint for putative further identification of fungal biomarkers for climate variations in this icy habitat. This is the first report on fungi from a rock-hosted cave ice block.

A Coupled System for Investigating the Physics of Wave–Ice Interactions

AbstractA coupled model system has been developed to investigate the physics of wave attenuation and ice edge retreat in the marginal ice zone (MIZ) at small scales [O(m)]. A phase-dependent finite-volume/finite-difference fluid dynamics model is used to simulate waves and currents, and a discrete element software package is employed to represent ice floes as bonded collections of individually tracked smaller particles. We first review the development of the coupled system, with an emphasis on the coupling software and the representation of wave–ice shear stress. Then we describe a series of simulations that were conducted to evaluate and qualitatively validate the performance of the coupled models. The system produced reasonable results for cases of a vertically oscillating ice block and a free-floating ice floe in monochromatic waves. In larger-scale simulations involving multiple ice floes and pancake ice, estimated transmission and reflection coefficients were similar to those obtained from alternate models and/or data, although numerical dissipation may have reduced estimates of transmitted wave energy in longer wave flumes. Challenges and limitations involving relative length scales in the coupled wave and ice domains are explained and discussed.

Formation, collapse and composition of ice banks in a macrotidal channel of the Bay of Fundy

Large ice blocks containing enough sediment to be denser than sea water form in the Minas Basin of the Bay of Fundy, Canada. Ice block composition and the timing of ice block formation were monitored to improve understanding of the potential threat to tidal power generators posed by collision with ice blocks. Field studies were carried out in 2012 and 2013 in the Kennetcook River, which is a tributary of the Minas Basin of the Bay of Fundy. In 2012, the cross-sectional area of the channel at the study site decreased by 21% due to the formation of ice walls. In 2013, it decreased by 24%. Large ice blocks separated from the ice walls during spring tides following a time lag of the minimum air temperature. The time lag was 20 days in 2012 and 21 days in 2013. Eleven percent of samples from ice blocks were denser than sea water.

Enhancing PV modules efficiency and power output using multi-concept cooling technique

The efficiency and power output of a PV module decrease at the peak of sunlight due to energy loss as heat energyand this reduces the module power output. Multi-concept cooling technique, a concept that involves three types of passive cooling, namely conductive cooling, air passive cooling and water passive cooling has the potential to tackle this challenge. The experiment was set up using two solar panels of 250 watts each with both modules mounted at a height of 37 cm to create room for air-cooling, with the application of water-cooling at the surface of one of the PV modules to reduce the surface temperature to 20 ∘C. The rear of the same module attached to an aluminium, Al heat sink. The other module also mounted was without water-cooling and Al heat sink attachment. The Al heat sink comprises aluminium plate attached with aluminium fins to aid cooling, and water at a reduced temperature achieved with the introduction blocks of ice facilitated the module surface cooling. Analysis of the power output achieved, carried out with the help of the equation for PV array power output with a derating factor of 80%. The experiment recorded an increase in output power of 20.96 watts, and an increase in efficiency of not less than 3% achieved thus making the module more efficient and productive.

Perancangan Sistem Photovoltaic untuk Mesin Pembuat Es di Pelabuhan Perikanan Sadeng

Currently, requirement of ice as medium fish cooling in PP Sadeng has not been fulfilled. This causes deterioration of fish quality when received by the consumers. The self production of ice blocks using ice maker machine has not solved this problem due to the highly operating costs, especially fuel. Photovoltaic (PV) systems are expected to overcome this problem. PV systems have high potential, since it is clean, environment-friendly, secure, and renewable. This paper explains the stages of PV system design, including PV module size, battery, solar charge controller, inverter, and also economic feasibility analysis. The results show that energy requirement of ice maker machines is 19,383.60 watts. The PV system consists of 40 units of 260 wp PV module, 82 units of battery 12V 100AH, 11 units of solar charge controller 40 A type MPPT, and 20 units of inverter DC-AC pure sine wave 1,200 W. Economic analysis shows that the life cycle cost (LCC) PV system designed is Rp513,704,165 for 25 years and levelized cost of energy (LCOE) of PV system is Rp1,401 per kWh.