Thermal budget of river ice covers during breakup

1989 ◽  
Vol 16 (1) ◽  
pp. 62-71 ◽  
Author(s):  
T. D. Prowse ◽  
P. Marsh
Keyword(s):  
Heat Input ◽  
Leading Edge ◽  
Field Measurements ◽  
Open Water ◽  
Heat Fluxes ◽  
River Ice ◽  
Ice Jams ◽  
Frazil Ice ◽  
Ice Melt ◽  
Ice Roughness

The magnitude and relative importance of atmosheric (air–ice) and hydrothermal (water–ice) heat fluxes to intact and fragmented river ice covers are studied for the case of a thermal breakup. Based on field measurements obtained from the Liard River, the atmospheric sources are shown to be dominant during the period of intact ice cover. Radiation was the primary heat source, but its effect was reduced by a granulation of the decaying columnar ice which increased the cover albedo to that comparable for melting snow. The hydrothermal heat input, even with frazil ice entrained within the flow, was comparable to that from atmospheric sources under low melt conditions. The hydrothermal heat flux dramatically increased with the arrival of the breakup front because of a rapid rise in water temperature and an increase in subsurface ice roughness. Higher surface roughness and lower albedo of the fragmented ice also increased the atmospheric heat fluxes, but these were small relative to the hydrothermal heat input near the leading edge of open water. Key words: floating ice, ice breakup, ice jams, ice melt.

scholarly journals Freeze-Up Ice Jam Formation in the River Bend, a Case Study on the Inner Mongolia Reach of Yellow River

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 631
Author(s):  
Shui-Xia Zhao ◽  
Wen-Jun Wang ◽  
Xiao-Hong Shi ◽  
Sheng-Nan Zhao ◽  
Ying-Jie Wu ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Yellow River ◽  
Open Water ◽  
River Ice ◽  
Freezing Process ◽  
Ice Jams ◽  
Narrow Channels ◽  
Frazil Ice ◽  
Ice Jam ◽  
Bed Changes

Concern has been expressed regarding the impacts of climate change on river ice and ice jam formation in cold regions. Ice jams are easily initiated in bends and narrow channels and cause disasters. In this study, observations and remote sensing monitoring are used to study the freeze-up ice jam formation of bends. Sediment transport and freezing process of the river interact, influencing bed changes profile and sedimentary budget. River ice processes, channel evolution, ice hydro-thermodynamics, and ice jam accumulation are explored. The results show that the channel topography determines the river thalweg, and that the channel elevation interacts with the river ice through sediment transport. The channel shrinkage increases the probability of ice jam, and the sharp bend is prone to ice jam formation. Under the effect of secondary circulation flow in the bend and in the outer bank, the juxtaposed freeze-up and the hummocky ice cover occur in the same location, and frazil ice accumulates under the junction of the main channel and the shoals. Affected by the increase of the hydraulic slope and the velocity downstream, open water reaches develops downstream of the ice accumulation. An open water section is emerged upstream of the bend, due to the ice deposition, and partly cut-off supply of the frazil.

scholarly journals Variation in water level under ice-jammed condition – field investigation and experimental study

2005 ◽  
Vol 36 (1) ◽  
pp. 65-84 ◽  
Author(s):  
Jueyi Sui ◽  
Bryan W. Karney ◽  
Daxian Fang
Keyword(s):  
Water Level ◽  
Yellow River ◽  
Experimental Studies ◽  
Field Investigation ◽  
River Ice ◽  
Experimental Investigations ◽  
Physical Parameters ◽  
Ice Jams ◽  
Frazil Ice ◽  
Ice Concentration

This paper presents the impacts of frazil ice jams on the variation in water level at the Hequ Reach of the Yellow River in China. Based on both field observations and experimental studies, it is found that both the evolution of frazil ice jams and the associated variation in water level depend upon an interesting interaction between hydraulic variables during the ice-jammed period. In particular, the critical Froude number governing the formation of river ice jams and their upstream propagation is about 0.09. The water level during ice-jammed periods depends not only on the slope of the water surface and the water level under open-water conditions with the same discharge, but also on the length of the ice jam and the ice concentration in the water. Moreover, the field investigations show that the thickness of river ice strongly influences the variation in water level during ice-jammed periods. Empirical relationships are derived to quantify the relationship between the highest water level during ice periods and related physical parameters. To confirm the field results, and to explore the influence of ice discharge on the variation in water level, experimental studies were also conducted. These results confirm that the ice concentration plays a key role in the variation in water level and the jam thickness. Given the complexity of the jamming processes, surprisingly good agreement is observed between field and experimental investigations.

Ice jam release surges, ice runs, and breaking fronts: field measurements, physical descriptions, and research needs

2003 ◽  
Vol 30 (1) ◽  
pp. 113-127 ◽  
Author(s):  
Martin Jasek
Keyword(s):  
Unsteady Flow ◽  
Field Measurements ◽  
Open Water ◽  
Two Phase ◽  
Ice Jams ◽  
Water Ice ◽  
Flow Models ◽  
Ice Jam ◽  
Recent Developments ◽  
Break Up

Surges or flood waves made up of ice and water resulting from the release of ice jams can be destructive to life and property and are also one of the more complicated problems in river ice engineering. The interaction between the ice mechanics and unsteady flow leads to results that are often unpredictable with open water unsteady flow models. There are considerable differences of opinion on the degree of significance of this water–ice interaction. There have also been recent developments in two-phase unsteady flow modelling which are capable of handling these complicated situations. It is the aim of this paper to present both quantitative data and qualitative observations on ice runs and breaking fronts to provide insight to the physical processes involved as and possible sources of model calibration data.Key words: ice jam, surge, unsteady flow, ice run, ice jam release, breaking front, break-up, breakup, break-up front.

scholarly journals A Simplified Ice–Ocean Coupled Model for the Antarctic Ice Melt Season

2005 ◽  
Vol 35 (2) ◽  
pp. 188-201 ◽  
Author(s):  
Kay I. Ohshima ◽  
Sohey Nihashi
Keyword(s):  
Sea Ice ◽  
Mixed Layer ◽  
Heat Input ◽  
Coupled Model ◽  
Open Water ◽  
Two Dimensions ◽  
Antarctic Ocean ◽  
Ice Melt ◽  
Ice Concentration ◽  
The Antarctic

Abstract In the Antarctic Ocean, sea ice melts mostly by warming of the ocean mixed layer through heat input (mainly solar radiation) in open water areas. A simplified ice–upper ocean coupled model is proposed in which sea ice melts only by the ocean heat supplied from the air. The model shows that the relationship between ice concentration (i.e., fraction, C) and mixed layer temperature (T) converges asymptotically with time (C–T relationship), which agrees with observed C–T plots during summer in the sector 25°–45°E. This relationship can be used for estimating the bulk heat transfer coefficient between ice and ocean by fitting to observations, and a value of 1.2 × 10−4 m s−1 is obtained. The model shows that the ratio of the heat used for melting to the heat input through open water is inclined to be determined as a function of ice concentration. For typical conditions in the Antarctic ice melt season, the ratio ranges mostly between 0.7 and 0.9. When the model is extended to two dimensions in the meridional direction, with the inclusion of wind forcing, it approximately reproduces the meridional retreat of the Antarctic sea ice. This two-dimensional model can describe the open water–albedo feedback effect, which partly explains the year-to-year variation of the sea-ice retreat in the Antarctic Ocean.

Modelling water temperature beneath river ice covers

1990 ◽  
Vol 17 (1) ◽  
pp. 36-44 ◽  
Author(s):  
Philip Marsh
Keyword(s):  
Heat Flux ◽  
Water Temperature ◽  
Water Depth ◽  
Frictional Heating ◽  
Ice Cover ◽  
Heat Fluxes ◽  
River Ice ◽  
Simple Method ◽  
Ice Melt ◽  
Bed Roughness

The water temperature beneath river ice covers has an important influence on the heat flux to the overlying ice cover and on ice melt. Measurements of water temperature beneath the Liard River ice cover showed that prior to spring breakup, the water temperature was always between 0.0 and 0.025 °C, with important cross-channel and diurnal variations. The lowest temperatures were controlled by the bed heat flux and frictional heating, while variations above these minimum values were explained by changes in solar radiation. Using measurements of these heat fluxes, in conjunction with measurements of ice and bed roughness, water depth and velocity, and slope, a simple method which assumes the similarity between heat and momentum transfer was able to accurately predict water temperatures beneath the ice cover. During breakup when the river had both ice-free and ice-covered sections, water temperatures rose to a few degrees above 0 °C. When this water entered an ice-covered reach, the water temperature declined rapidly to near 0 °C within 10 km. This temperature decay was predicted from measurements of the initial temperature, ice and bed roughness, and water depth. Key words: water temperature, ice, thermal regime, ice melt.

Heat and mass balance of an ablating ice jam

1990 ◽  
Vol 17 (4) ◽  
pp. 629-635 ◽  
Author(s):  
Terry D. Prowse
Keyword(s):  
Mass Balance ◽  
Field Data ◽  
Heat Fluxes ◽  
Relative Importance ◽  
Ice Jams ◽  
Theoretical Methods ◽  
Ice Melt ◽  
Ice Jam ◽  
Ice Breakup ◽  
Atmospheric Heat

This paper reports on the heat and mass balance of an ablating ice jam at the confluence of the Liard and Mackenzie rivers in the spring of 1983. From May 6 to May 9, sufficient data were collected to determine the magnitude and relative importance of the major heat fluxes that caused thermal decay of the ice jam. The total atmospheric heat input of 1.25 × 108 MJ and the much larger contribution from hydrothermal sources of 9.80 × 109 MJ resulted in a total melt of 3.24 × 107 m3 of ice within the jam. These data in combination with previous results regarding jam dimensions permitted calculation of ice jam porosity, a variable frequently used in hydraulic studies of river ice jams although unverified by field data. The largest potential error in the calculations was related to the accuracy of water temperature measurement. Accounting for this resulted in an estimate of porosity of 0.38 ± 10% which lends credence to the commonly assumed value of 0.40. Details of the field conditions, instrumentation, theoretical methods, and results of the energy and mass balance analyses are described. Key words: floating ice, ice breakup, ice jams, ice melt, ice porisity.

Characteristics of a separated flow past a semicircular leading-edge airfoil model under different imposed pressure gradient

2021 ◽  
pp. 095441002110212
Author(s):  
K Anand ◽  
KT Ganesh
Keyword(s):  
Boundary Layer ◽  
Particle Image Velocimetry ◽  
Pressure Gradient ◽  
Particle Image ◽  
Separation Bubble ◽  
Separated Flow ◽  
Leading Edge ◽  
Field Measurements ◽  
Bench Mark ◽  
Image Velocimetry

The effect of pressure gradient on a separated boundary layer past the leading edge of an airfoil model is studied experimentally using electronically scanned pressure (ESP) and particle image velocimetry (PIV) for a Reynolds number ( Re) of 25,000, based on leading-edge diameter ( D). The features of the boundary layer in the region of separation and its development past the reattachment location are examined for three cases of β (−30°, 0°, and +30°). The bubble parameters such as the onset of separation and transition and the reattachment location are identified from the averaged data obtained from pressure and velocity measurements. Surface pressure measurements obtained from ESP show a surge in wall static pressure for β = −30° (flap deflected up), while it goes down for β = +30° (flap deflected down) compared to the fundamental case, β = 0°. Particle image velocimetry results show that the roll up of the shear layer past the onset of separation is early for β = +30°, owing to higher amplification of background disturbances compared to β = 0° and −30°. Downstream to transition location, the instantaneous field measurements reveal a stretched, disoriented, and at instances bigger vortices for β = +30°, whereas a regular, periodically shed vortices, keeping their identity past the reattachment location, is observed for β = 0° and −30°. Above all, this study presents a new insight on the features of a separation bubble receiving a disturbance from the downstream end of the model, and these results may serve as a bench mark for future studies over an airfoil under similar environment.

Progress in the study and management of river ice jams

2008 ◽  
Vol 51 (1) ◽  
pp. 2-19 ◽  
Author(s):  
Spyros Beltaos
Keyword(s):  
River Ice ◽  
Ice Jams

Aerodynamic performance effects due to small leading-edge ice (roughness) on wings and tails

1993 ◽  
Vol 30 (6) ◽  
pp. 807-812 ◽  
Author(s):  
Walter O. Valarezo ◽  
Frank T. Lynch ◽  
Robert J. McGhee
Keyword(s):  
Leading Edge ◽  
Aerodynamic Performance ◽  
Ice Roughness ◽  
Performance Effects

Vortex formation on surging aerofoils with application to reverse flow modelling

2018 ◽  
Vol 859 ◽  
pp. 59-88 ◽  
Author(s):  
Philip B. Kirk ◽  
Anya R. Jones
Keyword(s):  
Surface Pressure ◽  
Reverse Flow ◽  
Vortex Formation ◽  
Three Dimensional ◽  
Tangential Velocity ◽  
Leading Edge ◽  
Field Measurements ◽  
Reduced Frequency ◽  
Advance Ratio ◽  
Convection Speed

The leading-edge vortex (LEV) is a powerful unsteady flow structure that can result in significant unsteady loads on lifting blades and wings. Using force, surface pressure and flow field measurements, this work represents an experimental campaign to characterize LEV behaviour in sinusoidally surging flows with widely varying amplitudes and frequencies. Additional tests were conducted in reverse flow surge, with kinematics similar to the tangential velocity profile seen by a blade element in recent high-advance-ratio rotor experiments. General results demonstrate the variability of LEV convection properties with reduced frequency, which greatly affected the average lift-to-drag ratio in a cycle. Analysis of surface pressure measurements suggests that LEV convection speed is a function only of the local instantaneous flow velocity. In the rotor-comparison tests, LEVs formed in reverse flow surge were found to convect more quickly than the corresponding reverse flow LEVs that form on a high-advance-ratio rotor, demonstrating that rotary motion has a stabilizing effect on LEVs. The reverse flow surging LEVs were also found to be of comparable strength to those observed on the high-advance-ratio rotor, leading to the conclusion that a surging-wing simplification might provide a suitable basis for low-order models of much more complex three-dimensional flows.

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