Water Temperature Distribution Research Articles

Numerical modelling of thermally induced desiccation of geosynthetic clay liners observed in laboratory experiments

ABSTRACT: A fully coupled model is used to simulate the results of large-scale laboratory tests that investigated the non-isothermal behaviour of geosynthetic clay liners in landfill basal liner applications. Results of numerical simulations of the laboratory tests in terms of water content, capillary pressure, temperature and stress distributions are presented, and encouraging agreement between the numerical and experimental results is achieved. Under the conditions examined, a 25°C/m temperature gradient led to the development of tensile stresses within the GCL, increasing the resultant likelihood of cracking. A Poisson's ratio of 0.25 resulted in predicted horizontal tensile stresses supporting qualitative observation of desiccation cracking in the GCLs. One important implication of the work reported herein is that elevated temperatures need not occur for extended periods to create the risk of desiccation.

Factors influencing thermal structure in a tributary bay of Three Gorges Reservoir

To better understand the factors influencing the thermal structure of tributaries in the Three Gorges Reservoir (TGR), a well validated three-dimensional hydrodynamic and water temperature model was proposed to simulate the water temperature distribution in the Xiangxi Bay, a representative tributary of TGR. The numerical results show that water temperature stratification seasonally occurred in the Xiangxi Bay, with stable vertical temperature profiles. It is found from the numerical experiments that three key factors are responsible for the formation of water temperature structure: (1) very often, the locations of thermocline are mainly determined by wind speeds, and the higher the wind speed is, the deeper the thermocline is located beneath the water surface, which could be expressed by a fitted exponential function, (2) the thermal structure is affected by static stability of water column, and the thermocline becomes closer to the water surface and its thickness increases with the increase of temperature, (3) due to the effect of the thermal density inflow, the water temperature of the hypolimnion tends to be uniform, however, even under the condition of larger inflow discharge, the influence of the inflow on the epilimnion and the thermocline is not significant.

Using Instream Water Temperature Forecasts for Fisheries Management: An Application in the Pacific Northwest1

Huang, Biao, Christian Langpap, and Richard M. Adams, 2011. Using Instream Water Temperature Forecasts for Fisheries Management: An Application in the Pacific Northwest. Journal of the American Water Resources Association (JAWRA) 47(4):861-876. DOI: 10.1111/j.1752-1688.2011.00562.x Abstract: Water temperature is an important factor affecting aquatic life within the stream environment. Cold water species, such as salmonids, are particularly susceptible to elevated water temperatures. This paper examines the potential usefulness of short-term (7 to 10 days) water temperature forecasts for salmonid management. Forecasts may be valuable if they allow the water resource manager to make better water allocation decisions. This study considers two applications: water releases from Lewiston Dam for management of adult Chinook salmon (Oncorhynchus tshawytscha) in the Klamath River and leasing water from agriculture for management of steelhead trout (Oncorhynchus mykiss) in the John Day River. We incorporate biophysical models and water temperature distribution data into a Bayesian framework to simulate changes in fish populations and the corresponding opportunity cost of water under different levels of temperature forecast reliability. Simulation results indicate that use of the forecasts results in increased fish production and that marginal costs decline as forecast reliability increases, suggesting that provision and use of such stream temperature forecasts would have potential value to society.

The influence of an exceptional Po River flood on the physical and chemical oceanographic properties of the Adriatic Sea

Physical and chemical characteristics of the Adriatic Sea during 2001 are analyzed to better understand the influence of an exceptional flooding of the Po River (the largest river flowing into the Adriatic Sea) occurred in October 2000. Spatial and temporal distributions of water temperature, salinity, dissolved oxygen and nutrients over the basin are presented. To better understand the impact of river flood during 2001, an analysis of a data-set along a transect during the years 1999–2002 is carried out. Results confirmed that the Po River outflows strongly affect the physical and chemical characteristics of the basin. In particular, during 2001, a sharp decrease in salinity and an increase in nutrient and fluorescence concentrations occurred in the northwestern Adriatic Sea after the 2000 flood event. The amount of nutrients transported during the river flood into the northwestern part of the basin is depleted by phytoplankton uptake until April 2001. All the nutrients were consumed before they could enrich the eastern coast, even though the freshwater input extends towards the Croatian coast. The Po River discharge flowing into the North Adriatic Sea during October–November 2000 (about 5000 m 3/s) is twice the mean discharge of the 2-month period (about 2000 m 3/s) and diluting the basin sufficiently to influence the North Adriatic Deep Water formation, almost absent in winter 2001. The flood event contributed to modifying the physical and chemical dynamics of the Adriatic Sea and its influence is clearly visible even 5–6 months later.

The insensitivity of thermal preferences to various thermal gradient profiles in newts

Many ectotherms possess the ability to behaviourally regulate their body temperatures. Thermoregulatory behaviour is affected by various biotic and abiotic factors, which may cause a substantial bias in the laboratory estimates of preferred body temperatures (Tp). We examined thermoregulatory behaviour in alpine newts, Ichthyosaura (formerly Triturus) alpestris, in both horizontal linear and vertical nonlinear thermal gradients, to evaluate the influence of a disparate water temperature distribution on their thermal preferences. Newt positions in thermal gradients differed from those in constant temperatures, which indicates their thermal preferences in both experimental setups. The mean and range of body temperatures showed similar values in both types of aquatic thermal gradients. We concluded that under a sufficiently wide range of environmental temperatures, newt thermal preferences are largely insensitive to the thermal gradient profile. This supports the suitability of Tp estimates for further experimental and comparative studies in newts.

Experimental study of the energy and thermal comfort performance of chilled ceiling panels

This article presents the results of a study performed to obtain the main operating characteristics of a chilled heating ceiling system in cooling mode. An experimental analysis of the cooling ceiling system in a climatic chamber is presented in order to evaluate the behavior of its cooling capacity, pressure drop, and thermal comfort. The purpose of the present study is to evaluate the influence of certain factors, such as the ventilation strategy, water mass flow rate, water temperature, and load distribution, on the global behavior and performance of the system. The results show that a high cooling load can be removed, and also a high degree of thermal comfort can be achieved, with this kind of system. However, strong influences of the heat sources distribution and surface temperatures inside the room on its performance are observed, especially for thermal comfort conditions (asymmetric thermal radiation).

Use of Advanced Meteorological Model Output for Coastal Ocean Modeling in Puget Sound

It is a great challenge to specify meteorological forcing in estuarine and coastal circulation modeling using observed data because of the lack of complete datasets. As a result of this limitation, water temperature is often not simulated in estuarine and coastal modeling, with the assumption that density-induced currents are generally dominated by salinity gradients. However, in many situations, temperature gradients could be sufficiently large to influence the baroclinic motion. In this paper, we present an approach to simulate water temperature using outputs from advanced meteorological models. This modeling approach was applied to simulate annual variations of water temperatures of Puget Sound, a fjordal estuary in the Pacific Northwest of USA. Meteorological parameters from North American Region Re-analysis (NARR) model outputs were evaluated with comparisons to observed data at real-time meteorological stations. Model results demonstrated that NARR outputs can be used to drive coastal ocean models for realistic simulations of long-term water-temperature distributions in Puget Sound. Model results indicated that the net flux from NARR can be further improved with the additional information from real-time observations.

THE VALUE OF IN‐STREAM WATER TEMPERATURE FORECASTS FOR FISHERIES MANAGEMENT

Water temperature is an important factor affecting aquatic life within the stream environment. Cold water species, such as salmonids, are particularly susceptible to elevated water temperatures. This paper examines the economic value of short‐term water temperature forecasts for salmonid management. Forecasts may have economic value if they allow the water resource manager to make better water allocation decisions. This study considers two applications: water releases for management of Chinook salmon in the Klamath River and leasing water from agriculture for management of steelhead trout in the John Day River. We incorporate biophysical models and water temperature distribution data into a Bayesian framework to simulate changes in fish populations and the corresponding benefit from recreational fishing and opportunity cost of water under different temperature forecast accuracies. Simulation results indicate that use of the forecasts results in increased fish production and that marginal costs decline and net benefits increase as forecast accuracy increases, suggesting that provision and use of such stream temperature forecasts would have value to society.(JELQ22, Q25, Q28, Q50)

Utilization improvement of PDMS and fluoropolymers by mutual application

We investigated about the utilization improvement of the PDMS and fluoropolymers by mutual application in environmental analysis. We were conducted the direct fluorination with mild condition on the PDMS films and analyzed its surfaces before and after fluorination. The results of FTIR and SEM analysis on the PDMS films showed that the film surfaces were fluorinated without irreversible deformation by the fluorination. During the fluorination, the measured contact angles of water and several alcohols on the PDMS films decreased with time and that of most alcohols decreased to 0 after 30 minutes. The surface energy of fluorinated PDMS films has increased by 2 times. Also, we investigated the influence factors on the change of permeation rate of water through PDMS tubes with time. It was observed that the change of permeation rate of water through PDMS tube was affected by temperature, water phase and spatial distribution of water. From these results, we could verify the principal causes of the decrease of permeation rate of water through PDMS tube with time and proposed a new experimental setup for reducing the variation of permeation rate of water less than 2%.

An approach to reproduce water temperature structure in the Glacier Lake in Himalaya

This study aims to reproduce the water temperature structure in the Imja glacial lake using the 3D-Hydrodynamic model "Imja-3D" and the hypothetic meteorological datasets at the Imja glacial lake. The one-year datasets of hourly average air temperature were hypothesized using the temperature datasets at Namche Bazaar in 2008. The datasets of the wind speeds and the wind directions were considered diurnal pattern of the regional climate features in the Solukhumbu region. The model reproduced the water temperature structure of the lake in July 2008. The thermocline appeared near the lake water surface. The water temperature (2-3 degree) distribution was shown in mid layer. These results showed the similar water temperature structure on the observed one in the Imja glacial lake in 1997.

Innovation in radioactive wastewater-stream management. Part II: theoretical model and experimental verification

The present work is the second part of the authors’ innovative method for radioactive wastewater-stream management, by volume reduction, by a mutual heating and humidification of a compressed dry air introduced through the wastewater. In this part, to determine the optimal operating conditions, a theoretical model describing volume reduction of the radioactive wastewater stream is achieved. A set of first-order simultaneous differential equations describing the bubble humidity, temperature, liquid temperature, and mass diffusion to the bubbles variations, are obtained through the mass and energy conservations. A set of coupled first-order differential equations are used to solve for the humidity ratio, water diffused to the air stream, water temperature and humid air stream temperature distributions through the bubbling column. These coupled differential equations are simultaneously solved numerically by a developed computer program using the fourth-order Runge–Kutta method. Therefore, the behaviour of the air bubble state variables with column height can be predicted and optimised. Moreover, the design curves of the volumetric reduction of the wastewater streams are obtained and assessed at the different operating conditions. An experimental set-up was constructed to verify the suggested model. Comprehensive comparison between suggested model results, recent experimental measurements and the results of previous works was carried out and assessed. A good agreement between experimental and theoretical model is obtained. A semi-empirical correlation is obtained together with design curve of bubbling column.

APPLICABILITY OF MEAN FIELD APPROXIMATION TO NUMERICAL EXPERIMENTS OF THERMAL CONVECTION UNDER THE CONDITION OF LAKE BIWA

This paper describes the fundamental characteristics of the numerical experiments on thermal convection carried out under the condition of the northern part of Lake Biwa. Since the temporal change of vertical distribution of water temperature during the cooling period can be reproduced by means of a simple simulation model of thermal convection in the previous study, the numerical results of thermal convection simulation was firstly shown under wide range of cooling rates at water surface. We considered to clarify the basic features of these numerical data on thermal convection using a stochastic model and its mean field approximation. It was shown through the comparison of theoretical results to numerical results that the mean field approximation with some refinement is applicable to the numerical experiments to some extent.

Characterization of convective heat transfer in channels of small cross section using digital interferometry

Forced convection in channels of small cross sectional dimensions has been recommended as an effective heat removal method for electronic components and packages. Many of the experimental results reported in the literature on the heat transfer performance of small-cross section channels are of contradicting nature, even though some generally agreeing results are also found. One of the probable reasons for the deviations, as suggested by investigators, is the intrusive nature of measurement techniques, which interferes with the flow field. Hence a non intrusive measurement technique is preferable for temperature measurement in small channels. The present work is aimed at developing an interferometric method for convective heat transfer measurement in a liquid medium flowing through channels of small cross sectional dimensions, with hydraulic diameters ranging from 12 to 3 mm and characterizing the nature of fluid flow and heat transfer in these channels. Mach–Zehnder interferometric arrangement is used to obtain the temperature distributions in water flowing through the channels, which are further analyzed digitally to obtain the local heat transfer coefficients and Nusselt numbers. The results are compared and contrasted with classical results for channel flow and heat transfer, and attempt has been made to interpret the variations and deviations observed. The experimental study has been performed under different fluid velocities in the laminar flow regime, and under various wall heat fluxes corresponding to the heat dissipation range expected in microelectronic devices. Parametric variations for the heat transfer performance have been obtained and correlated using the experimental results.

Spatial–Temporal Variability of Great Slave Lake Levels From Satellite Altimetry

The study of lake-level variability of five selected areas across Great Slave Lake (GSL) using satellite altimetry is presented. Data from Topex/Poseidon (TP) and Jason-1 (J1) missions at GSL for the ice-free seasons of 1993-2002 and 2002-2008, respectively, reveal lower performance of J1 for areas closer to 20 km from the coastline compared to 10 km for TP. A calculated bias of 6.99 cm was subtracted to J1 range since TP has better tracking of shoreline waters and lower data rejection. High correlation coefficients for the relative rate of change between lake altimetry heights (LAHs) and corresponding gauge data for Yellowknife Bay and Hay River support the use of LAH changes as effective indicators of variability at GSL. Differences in LAH between the five areas indicate a nonuniform slope which we relate more to variability of the surface water temperature distribution than wind effects. The deeper and colder areas are associated to the least change of LAH gradient through time; therefore, they represent ideal areas to study interannual climate variability. A potential correlation between areas with higher variability in LAH gradients and higher changes in modeled surface water temperatures during the 2003 ice free season is observed.

Time-resolved radiation beam profiles in water obtained by ultrasonic tomography

This paper presents a practical ultrasonic system for near real-time imaging of spatial temperature distributions in water caused by absorption of radiation. Initial testing with radiation from a highly attenuated infrared lamp demonstrates that the system is able to map sub-millikelvin temperature changes, thus making it suitable for characterizing dose profiles of therapy-level ionizing radiation beams. The system uses a fan-beam tomographic reconstruction algorithm to invert time-of-flight data derived from ultrasonic pulses produced and detected by a circular array of transducers immersed in water. Temperature dependence of the speed of sound in water permits the conversion of these measured two-dimensional velocity distributions into temperature distributions that indicate the absorbed radiation dose. The laboratory prototype, based on a 128-element transducer array, is used to acquire temperature maps of a 230 mm × 230 mm area every 4 s with sub-millikelvin resolution in temperature and about 5 mm resolution in space. Earlier measurements with a single-channel version of this prototype suggest refinements in signal-conditioning electronics and signal-processing algorithms that would allow the present instrument to resolve temperature changes as low as a few microkelvin. Possible applications include real-time intensity profiling of radiation beams and three-dimensional characterization of the absorbed dose.

Food Powders Flowability Characterization: Theory, Methods, and Applications

Characterization of food powders flowability is required for predicting powder flow from hoppers in small-scale systems such as vending machines or at the industrial scale from storage silos or bins dispensing into powder mixing systems or packaging machines. This review covers conventional and new methods used to measure flowability in food powders. The method developed by Jenike (1964) for determining hopper outlet diameter and hopper angle has become a standard for the design of bins and is regarded as a standard method to characterize flowability. Moreover, there are a number of shear cells that can be used to determine failure properties defined by Jenike's theory. Other classic methods (compression, angle of repose) and nonconventional methods (Hall flowmeter, Johanson Indicizer, Hosokawa powder tester, tensile strength tester, powder rheometer), used mainly for the characterization of food powder cohesiveness, are described. The effect of some factors preventing flow, such as water content, temperature, time consolidation, particle composition and size distribution, is summarized for the characterization of specific food powders with conventional and other methods. Whereas time-consuming standard methods established for hopper design provide flow properties, there is yet little comparative evidence demonstrating that other rapid methods may provide similar flow prediction.

A Study on Air-Sea Mixing due to Wind and Wave under Strong Wind Condition

Since major driving forces of vertical mixing processes are wind and wind wave mixing, the boundary condition of turbulent kinetic energy flux at the ocean face is formulated as cubic of friction velocity by Craig-Banner relation. It is not well verified in general conditions including wave conditions and shallow water environment. This study estimates effects of wave conditions on vertical mixing processes at the ocean upper layers in the stormy condition. The field observation was conducted during typhoon Melor in 2009. The observed water temperature distributions indicate importance of wind and wave induced mixing in the nearshore. The numerical results show that the wave induced vertical turbulent flux significantly influences on the water temperature and the current, respectively.

Synoptic-scale anomalies of Lake Ladoga surface temperature fields

Results of studying characteristic features of variability of the water surface temperature fields of Lake Ladoga during the open water period are presented. Anomalies and extreme deviations of real spatial distributions from those typical of the scales of synoptic variability are estimated. Typical surface temperature distribution of Lake Ladoga during an open water period occupies not more than 20% of the lake area. The near-shore shallow water area is characterized as an area of most anomalous water temperature distribution. The abnormality extent changes from month to month. July is the most anomalous month of the open water period.

Stream-aquifer interactions in the Maules Creek catchment, Namoi Valley, New South Wales, Australia

The interaction between surface-water streams and groundwater in the Maules Creek catchment of northern New South Wales, Australia has been investigated using a wide range of techniques. Zones of groundwater discharge were mapped by measuring the temperature and fluid electrical-conductivity distribution in bores and surface water. Zones where surface water appears to be recharging the aquifer were investigated by measuring the vertical head gradient between the stream and adjacent bores and by estimates of the decreasing surface flow. Geological heterogeneity appears to be the most significant factor in controlling exchange. Lithological information was assembled using geophysical logging of existing bores, supplemented by the results of electrical resistivity imaging. A preliminary water balance was assembled from the available State records of groundwater abstraction for irrigation, rainfall, evapotranspiration and flow gauging in Maules Creek and the adjacent Namoi River. The analysis has demonstrated the complexity of these coupled systems and gives an indication of the most efficient techniques to be deployed in the field to investigate these complex but important systems.

멸치의 산란기 수온이 어획량에 미치는 영향

The water temperature from 1980 to 2000 and the anchovy catch from 1990 to 2000 in the southeastern portion of the South Sea of Korea were used to illustrate the influence of water temperature on the catch of the anchovy, Engraulis japonica. 1993 and 1998 were selected as poor and good fishing years therefore, the horizontal and vertical distribution of water temperature and catch per unit effort in these years was compared. When the anchovy catch was lower, the water temperature at 10 m was also about <TEX>$0-2^{\circ}C$</TEX> lower than during a normal year, which resulted in the formation of a weak thermocline. Conversely, when the anchovy catch was higher, the water temperature at 10m was <TEX>$0-2^{\circ}C$</TEX> greater than during a normal year, which resulted in the formation of a strong thermocline at around 20 m.