Fluid property measurements study

NASA Technical Reports Server (NTRS)

Devaney, W. E.

1976-01-01

Fluid properties of refrigerant-21 were investigated at temperatures from the freezing point to 423 Kelvin and at pressures to 1.38 x 10 to the 8th power N/sq m (20,000 psia). The fluid properties included were: density, vapor pressure, viscosity, specific heat, thermal conductivity, thermal expansion coefficient, freezing point and bulk modulus. Tables of smooth values are reported.

Experimental Study of the Stability of Aircraft Fuels at Elevated Temperatures

NASA Technical Reports Server (NTRS)

Vranos, A.; Marteney, P. J.

1980-01-01

An experimental study of fuel stability was conducted in an apparatus which simulated an aircraft gas turbine fuel system. Two fuels were tested: Jet A and Number 2 Home Heating oil. Jet A is an aircraft gas turbine fuel currently in wide use. No. 2HH was selected to represent the properties of future turbine fuels, particularly experimental Reference Broad Specification, which, under NASA sponsorship, was considered as a possible next-generation fuel. Tests were conducted with varying fuel flow rates, delivery pressures and fuel pretreatments (including preheating and deoxygenation). Simulator wall temperatures were varied between 422K and 672K at fuel flows of 0.022 to 0.22 Kg/sec. Coking rate was determined at four equally-spaced locations along the length of the simulator. Fuel samples were collected for infrared analysis. The dependence of coking rate in Jet A may be correlated with surface temperature via an activation energy of 9 to 10 kcal/mole, although the results indicate that both bulk fluid and surface temperature affect the rate of decomposition. As a consequence, flow rate, which controls bulk temperature, must also be considered. Taken together, these results suggest that the decomposition reactions are initiated on the surface and continue in the bulk fluid. The coking rate data for No. 2 HH oil are very highly temperature dependent above approximately 533K. This suggests that bulk phase reactions can become controlling in the formation of coke.

Physical and chemical properties of some new perfluoropolyalkylether lubricants prepared by direct fluorination

NASA Technical Reports Server (NTRS)

Jones, W. R., Jr.; Bierschenk, T. R.; Juhlke, T. J.; Kawa, H.; Lagow, R. J.

1993-01-01

A series of perfluoropolyalkylether (PFPAE) fluids was synthesized by direct fluorination. Viscosity-temperature properties, oxidation stabilities, oxidation-corrosion properties, bulk modulus, lubricity, surface tension and density were measured. It was shown that as the carbon to oxygen ratio in the polymer repeating unit decreases, the viscometric properties improve, the fluids may become poorer boundary lubricants, the bulk modulus increases, the surface tension increases and the fluid density increases. The presence of difluoromethylene oxide units in the polymer does not significantly lower the oxidation and oxidation-corrosion stabilities as long as the difluoromethylene oxide units are separated by other units.

The temporal evolution of magnesium isotope fractionation during hydromagnesite dissolution, precipitation, and at equilibrium

NASA Astrophysics Data System (ADS)

Oelkers, Eric H.; Berninger, Ulf-Niklas; Pérez-Fernàndez, Andrea; Chmeleff, Jérôme; Mavromatis, Vasileios

2018-04-01

This study provides experimental evidence of the resetting of the magnesium (Mg) isotope signatures of hydromagnesite in the presence of an aqueous fluid during its congruent dissolution, precipitation, and at equilibrium at ambient temperatures over month-long timescales. All experiments were performed in batch reactors in aqueous sodium carbonate buffer solutions having a pH from 7.8 to 9.2. The fluid phase in all experiments attained bulk chemical equilibrium within analytical uncertainty with hydromagnesite within several days, but the experiments were allowed to continue for up to 575 days. During congruent hydromagnesite dissolution, the fluid first became enriched in isotopically light Mg compared to the dissolving hydromagnesite, but this Mg isotope composition became heavier after the fluid attained chemical equilibrium with the mineral. The δ26Mg composition of the fluid was up to ∼0.35‰ heavier than the initial dissolving hydromagnesite at the end of the dissolution experiments. Hydromagnesite precipitation was provoked during one experiment by increasing the reaction temperature from 4 to 50 °C. The δ26Mg composition of the fluid increased as hydromagnesite precipitated and continued to increase after the fluid attained bulk equilibrium with this phase. These observations are consistent with the hypothesis that mineral-fluid equilibrium is dynamic (i.e. dissolution and precipitation occur at equal, non-zero rates at equilibrium). Moreover the results presented in this study confirm (1) that the transfer of material from the solid to the fluid phase may not be conservative during stoichiometric dissolution, and (2) that the isotopic compositions of carbonate minerals can evolve even when the mineral is in bulk chemical equilibrium with its coexisting fluid. This latter observation suggests that the preservation of isotopic signatures of carbonate minerals in the geological record may require a combination of the isolation of fluid-mineral system from external chemical input and/or the existence of a yet to be defined dissolution/precipitation inhibition mechanism.

Indications of Bulk-Fluid Motion in Direct-Drive Implosions

NASA Astrophysics Data System (ADS)

Mannion, O. M.; Anderson, K. S.; Forrest, C. J.; Glebov, V. Yu.; Goncharov, V. N.; Knauer, J. P.; Radha, P. B.; Regan, S. P.; Sangster, T. C.; Stoeckl, C.

2017-10-01

The neutron spectrum produced by a burning plasma encodes essential information about the fusion products and serves as an important diagnostic for inertial confinement fusion experiments. At the Omega Laser Facility, neutron time-of-flight measurements are used to interpret the first and second moment of the neutron spectrum. These moments have been shown to be directly related to properties of the plasma, such as bulk fluid motion and apparent ion temperature. New measurement devices allow for unprecedented accuracy in the measurement of these moments and will provide a better understanding of the performance of direct-drive implosions. We present measurements of the first moment of the DT and D2 peaks in DT implosions and show that variations in the first moment indicate bulk fluid motion of the plasma. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

Analog geometry in an expanding fluid from AdS/CFT perspective

NASA Astrophysics Data System (ADS)

Bilić, Neven; Domazet, Silvije; Tolić, Dijana

2015-04-01

The dynamics of an expanding hadron fluid at temperatures below the chiral transition is studied in the framework of AdS/CFT correspondence. We establish a correspondence between the asymptotic AdS geometry in the 4 + 1 dimensional bulk with the analog spacetime geometry on its 3 + 1 dimensional boundary with the background fluid undergoing a spherical Bjorken type expansion. The analog metric tensor on the boundary depends locally on the soft pion dispersion relation and the four-velocity of the fluid. The AdS/CFT correspondence provides a relation between the pion velocity and the critical temperature of the chiral phase transition.

Effect of thermal aging on stability of transformer oil based temperature sensitive magnetic fluids

NASA Astrophysics Data System (ADS)

Kaur, Navjot; Chudasama, Bhupendra

2018-04-01

Synthesizing stable temperature sensitive magnetic fluids with tunable magnetic properties that can be used as coolant in transformers is of great interest, however not exploited commercially due to the lack of its stability at elevated temperatures in bulk quantities. The task is quite challenging as the performance parameters of magnetic fluids are strongly influenced by thermal aging. In this article, we report the effect of thermal aging on colloidal stability and magnetic properties of Mn1-xZnxFe2O4 magnetic fluids prepared in industrial grade transformer oil. As-synthesized magnetic fluids possess good dispersion stability and tunable magnetic properties. Effect of accelerated thermal aging on the dispersion stability and magnetic properties have been evaluated by photon correlation spectroscopy and vibration sample magnetometry, respectively. Magnetic fluids are stable under accelerated aging at elevated temperatures (from 50 °C to 125 °C), which is critical for their efficient performance in high power transformers.

Oxygen isotope fractionation between analcime and water - An experimental study

NASA Technical Reports Server (NTRS)

Karlsson, Haraldur R.; Clayton, Robert N.

1990-01-01

The oxygen isotope fractionation between analcime and water is studied to test the feasibility of using zeolites as low-temperature thermometers. The fractionation of oxygen isotopes between natural analcime and water is determined at 300, 350, and 400 C, and at fluid pressures ranging from 1.5 to 5.0 kbar. Also, isotope ratios for the analcime framework, the channel water, and bulk water are obtained. The results suggest that the channel water is depleted in O-18 relative to bulk water by a constant value of about 5 percent, nearly independent of temperature. The analcime-water fractionation curve is presented, showing that the exchange has little effect on grain morphology and does not involve recrystallization. The exchange is faster than any other observed for a silicate. The exchange rates suggest that zeolites in active high-temperature geothermal areas are in oxygen isotopic equilibrium with ambient fluids. It is concluded that calibrated zeolites may be excellent low-temperature oxygen isotope geothermometers.

Molecular aspect ratio and anchoring strength effects in a confined Gay-Berne liquid crystal

NASA Astrophysics Data System (ADS)

Cañeda-Guzmán, E.; Moreno-Razo, J. A.; Díaz-Herrera, E.; Sambriski, E. J.

2014-04-01

Phase diagrams for Gay-Berne (GB) fluids were obtained from molecular dynamics simulations for GB(2, 5, 1, 2) (i.e. short mesogens) and GB(3, 5, 1, 2) (i.e. long mesogens), which yield isotropic, nematic, and smectic-B phases. The long-mesogen fluid also yields the smectic-A phase. Ordered phases of the long-mesogen fluid form at higher temperatures and lower densities when compared to those of the short-mesogen fluid. The effect of confinement under weak and strong substrate couplings in slab geometry was investigated. Compared to the bulk, the isotropic-nematic transition does not shift in temprature significantly for the weakly coupled substrate in either mesogen fluid. However, the strongly coupled substrate shifts the transition to lower temperature. Confinement induces marked stratification in the short-mesogen fluid. This effect diminishes with distance from the substrate, yielding bulk-like behaviour in the slab central region. Fluid stratification is very weak for the long-mesogen fluid, but the strongly coupled substrate induces 'smectisation', an ordering effect that decays with distance. Orientation of the fluid on the substrate depends on the mesogen. There is no preferred orientation in a plane parallel to the substrate for the weakly coupled case. In the strongly coupled case, the mesogen orientation mimics that of adjacent fluid layers. Planar anchoring is observed with a broad distribution of orientations in the weakly coupled case. In the strongly coupled case, the distribution leans toward planar orientations for the short-mesogen fluid, while a marginal preference for tilting persists in the long-mesogen fluid.

Relationships between self-diffusivity, packing fraction, and excess entropy in simple bulk and confined fluids.

PubMed

Mittal, Jeetain; Errington, Jeffrey R; Truskett, Thomas M

2007-08-30

Static measures such as density and entropy, which are intimately connected to structure, have featured prominently in modern thinking about the dynamics of the liquid state. Here, we explore the connections between self-diffusivity, density, and excess entropy for two of the most widely used model "simple" liquids, the equilibrium Lennard-Jones and square-well fluids, in both bulk and confined environments. We find that the self-diffusivity data of the Lennard-Jones fluid can be approximately collapsed onto a single curve (i) versus effective packing fraction and (ii) in appropriately reduced form versus excess entropy, as suggested by two well-known scaling laws. Similar data collapse does not occur for the square-well fluid, a fact that can be understood on the basis of the nontrivial effects that temperature has on its static structure. Nonetheless, we show that the implications of confinement for the self-diffusivity of both of these model fluids, over a broad range of equilibrium conditions, can be predicted on the basis of knowledge of the bulk fluid behavior and either the effective packing fraction or the excess entropy of the confined fluid. Excess entropy is perhaps the most preferable route due to its superior predictive ability and because it is a standard, unambiguous thermodynamic quantity that can be readily predicted via classical density functional theories of inhomogeneous fluids.

Turbulent convective heat transfer of methane at supercritical pressure in a helical coiled tube

NASA Astrophysics Data System (ADS)

Wang, Chenggang; Sun, Baokun; Lin, Wei; He, Fan; You, Yingqiang; Yu, Jiuyang

2018-02-01

The heat transfer of methane at supercritical pressure in a helically coiled tube was numerically investigated using the Reynolds Stress Model under constant wall temperature. The effects of mass flux ( G), inlet pressure ( P in) and buoyancy force on the heat transfer behaviors were discussed in detail. Results show that the light fluid with higher temperature appears near the inner wall of the helically coiled tube. When the bulk temperature is less than or approach to the pseudocritical temperature ( T pc ), the combined effects of buoyancy force and centrifugal force make heavy fluid with lower temperature appear near the outer-right of the helically coiled tube. Beyond the T pc , the heavy fluid with lower temperature moves from the outer-right region to the outer region owing to the centrifugal force. The buoyancy force caused by density variation, which can be characterized by Gr/ Re 2 and Gr/ Re 2.7, enhances the heat transfer coefficient ( h) when the bulk temperature is less than or near the T pc , and the h experiences oscillation due to the buoyancy force. The oscillation is reduced progressively with the increase of G. Moreover, h reaches its peak value near the T pc . Higher G could improve the heat transfer performance in the whole temperature range. The peak value of h depends on P in. A new correlation was proposed for methane at supercritical pressure convective heat transfer in the helical tube, which shows a good agreement with the present simulated results.

Bulk Group-III Nitride Crystal Growth in Supercritical Ammonia-Sodium Solutions

NASA Astrophysics Data System (ADS)

Griffiths, Steven Herbert

Gallium nitride (GaN) and its alloys with indium nitride (InGaN) and aluminum nitride (AlGaN), collectively referred to as Group-III Nitride semiconductors, have enabled white solid-state lighting (SSL) sources and power electronic devices. While these technologies have already made a lasting, positive impact on society, improvements in design and efficiency are anticipated by shifting from heteroepitaxial growth on foreign substrates (such as sapphire, Si, SiC, etc.) to homoepitaxial growth on native, bulk GaN substrates. Bulk GaN has not supplanted foreign substrate materials due to the extreme conditions required to achieve a stoichiometric GaN melt (temperatures and pressures in excess of 2200°C and 6 GPa, respectively). The only method used to produce bulk GaN on an industrial scale is hydride vapor phase epitaxy (HVPE), but the high cost of gaseous precursors and relatively poor crystal quality have limited the adoption of this technology. A solution growth technique known as the ammonothermal method has attracted interest from academia and industry alike for its ability to produce bulk GaN boules of exceedingly high crystal quality. The ammonothermal method employs supercritical ammonia (NH3) solutions to dissolve, transport, and crystallize GaN. However, ammonothermal growth pressures are still relatively high (˜200 MPa), which has thus far prevented the acquisition of fundamental crystal growth knowledge needed to efficiently (i.e. through data-driven approaches) advance the field. This dissertation focused on addressing the gaps in the literature through two studies employing in situ fluid temperature analysis. The first study focused on identifying the solubility of GaN in supercritical NH3-Na solutions. The design and utilization of in situ and ex situ monitoring equipment enabled the first reports of the two-phase nature of supercritical NH3-Na solutions, and of Ga-alloying of Ni-containing autoclave components. The effects of these error sources on the gravimetric determination of GaN solubility were explored in detail. The second study was aimed at correlating autoclave dissolution and growth zone fluid temperatures with bulk GaN crystal growth kinetics, crystal quality, and impurity incorporation. The insights resulting from this analysis include the identification of the barrier between mass transport and surface integration-limited GaN growth regimes, GaN crystal shape evolution with fluid temperature, the sensitivity of (0001)-orientation crystal quality with fluid temperature, and impurity-specific incorporation activated from the dissolution and growth zones of the autoclave. The results of the aforementioned studies motivated a paradigm-shift in ammonothermal growth. To address this need, a fundamentally different crystal growth approach involving isothermal solutions and tailor-made Group-III alloy source materials was developed/demonstrated. This growth method enabled impurity incorporation reduction compared to traditional ammonothermal GaN growth, and the realization of bulk, ternary Group-III Nitride crystals.

Calculation of Macrosegregation in an Ingot

NASA Technical Reports Server (NTRS)

Poirier, D. R.; Maples, A. L.

1986-01-01

Report describes both two-dimensional theoretical model of macrosegregation (separating into regions of discrete composition) in solidification of binary alloy in chilled rectangular mold and interactive computer program embodying model. Model evolved from previous ones limited to calculating effects of interdendritic fluid flow on final macrosegregation for given input temperature field under assumption of no fluid in bulk melt.

Longitudinal and bulk viscosities of Lennard-Jones fluids

NASA Astrophysics Data System (ADS)

Tankeshwar, K.; Pathak, K. N.; Ranganathan, S.

1996-12-01

Expressions for the longitudinal and bulk viscosities have been derived using Green Kubo formulae involving the time integral of the longitudinal and bulk stress autocorrelation functions. The time evolution of stress autocorrelation functions are determined using the Mori formalism and a memory function which is obtained from the Mori equation of motion. The memory function is of hyperbolic secant form and involves two parameters which are related to the microscopic sum rules of the respective autocorrelation function. We have derived expressions for the zeroth-, second-and fourth- order sum rules of the longitudinal and bulk stress autocorrelation functions. These involve static correlation functions up to four particles. The final expressions for these have been put in a form suitable for numerical calculations using low- order decoupling approximations. The numerical results have been obtained for the sum rules of longitudinal and bulk stress autocorrelation functions. These have been used to calculate the longitudinal and bulk viscosities and time evolution of the longitudinal stress autocorrelation function of the Lennard-Jones fluids over wide ranges of densities and temperatures. We have compared our results with the available computer simulation data and found reasonable agreement.

Apparatus and method for excluding gas from a liquid

DOEpatents

Murphy, Jr., Robert J.

1985-01-01

The present invention is directed to an apparatus and method for preventing diffusion of a gas under high pressure into the bulk of a liquid filling a substantially closed chamber. This apparatus and method is particularly useful in connection with test devices for testing fluid characteristics under harsh conditions of extremely high pressure and high temperature. These devices typically pressurize the liquid by placing the liquid in pressure and fluid communication with a high pressure inert gas. The apparatus and method of the present invention prevent diffusion of the pressurizing gas into the bulk of the test liquid by decreasing the chamber volume at a rate sufficient to maintain the bulk of the liquid free of absorbed or dissolved gas by expelling that portion of the liquid which is contaminated by the pressurizing gas.

Temperature rise and flow of Zr-based bulk metallic glasses under high shearing stress

NASA Astrophysics Data System (ADS)

Zhang, Weiguo; Ma, Mingzhen; Song, Aijun; Liang, Shunxing; Hao, Qiuhong; Tan, Chunlin; Jing, Qin; Liu, Riping

2011-11-01

Deformation of the bulk metallic glasses (BMGs) and the creation and propagation of the shear bands are closely interconnected. Shearing force was loaded on Zr41.2Ti13.8Cu12.5Ni10.0Be22.5(Vit.1) BMGs by cutting during the turning of the BMG rod. The temperature rise of alloy on the shear bands was calculated and the result showed that it could reach the temperature of the super-cooled liquid zone or exceed the melting point. The temperature rise caused viscous fluid flow and brought about the deformation of BMGs. This suggested that the deformation of BMGs was derived, at least to some extent, from the adiabatic shear temperature rise.

Radical polymerization of capillary bridges between micron-sized particles in liquid bulk phase as a low temperature route to produce porous solid materials.

PubMed

Hauf, Katharina; Riazi, Kamran; Willenbacher, Norbert; Koos, Erin

2017-10-01

We present a generic and versatile low temperature route to produce macro-porous bodies with porosity and pore size distribution that are adjustable in a wide range. Capillary suspensions, where the minor fluid is a monomer, are used as pre-cursors. The monomer is preferentially located between the particles, creating capillary bridges, resulting in a strong, percolating network. Thermally induced polymerization of these bridges at temperatures below 100 °C for less than 5 hours and subsequent removal of the bulk fluid yields macroscopic, self-supporting solid bodies with high porosity. This process is demonstrated using methylmethacrylate and hydroxyethylmethacrlyate with glass particles as a model system. The produced PMMA had a molecular weight of about 500.000 g/mol and dispersity about three. Application specific porous bodies, including PMMA particles connected by PMMA bridges, micron-sized capsules containing phase change material with high inner surface, and porous graphite membranes with high electrical conductivity, are also shown.

Radical polymerization of capillary bridges between micron-sized particles in liquid bulk phase as a low temperature route to produce porous solid materials

PubMed Central

Hauf, Katharina; Riazi, Kamran; Willenbacher, Norbert; Koos, Erin

2018-01-01

We present a generic and versatile low temperature route to produce macro-porous bodies with porosity and pore size distribution that are adjustable in a wide range. Capillary suspensions, where the minor fluid is a monomer, are used as pre-cursors. The monomer is preferentially located between the particles, creating capillary bridges, resulting in a strong, percolating network. Thermally induced polymerization of these bridges at temperatures below 100 °C for less than 5 hours and subsequent removal of the bulk fluid yields macroscopic, self-supporting solid bodies with high porosity. This process is demonstrated using methylmethacrylate and hydroxyethylmethacrlyate with glass particles as a model system. The produced PMMA had a molecular weight of about 500.000 g/mol and dispersity about three. Application specific porous bodies, including PMMA particles connected by PMMA bridges, micron-sized capsules containing phase change material with high inner surface, and porous graphite membranes with high electrical conductivity, are also shown. PMID:29503494

High energy power-law tail in X-ray binaries and bulk Comptonization due to an outflow from a disk

NASA Astrophysics Data System (ADS)

Kumar, Nagendra

2018-02-01

We study the high energy power-law tail emission of X-ray binaries (XRBs) by a bulk Comptonization process which is usually observed in the very high soft (VHS) state of black hole (BH) XRBs and the high soft (HS) state of the neutron star (NS) and BH XRBs. Earlier, to generate the power-law tail in bulk Comptonization framework, a free-fall converging flow into BH or NS had been considered as a bulk region. In this work, for a bulk region we consider mainly an outflow geometry from the accretion disk which is bounded by a torus surrounding the compact object. We have two choices for an outflow geometry: (i) collimated flow and (ii) conical flow of opening angle θ _b and the axis is perpendicular to the disk. We also consider an azimuthal velocity of the torus fluids as a bulk motion where the fluids are rotating around the compact object (a torus flow). We find that the power-law tail can be generated in a torus flow having large optical depth and bulk speed (>0.75 c), and in conical flow with θ _b > ˜ 30° for a low value of Comptonizing medium temperature. Particularly, in conical flow the low opening angle is more favourable to generate the power-law tail in both the HS state and the VHS state. We notice that when the outflow is collimated, then the emergent spectrum does not have power-law component for a low Comptonizing medium temperature.

Cosmological QCD phase transition in steady non-equilibrium dissipative Hořava–Lifshitz early universe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khodadi, M., E-mail: M.Khodadi@sbu.ac.ir; Sepangi, H.R., E-mail: hr-sepangi@sbu.ac.ir

We study the phase transition from quark–gluon plasma to hadrons in the early universe in the context of non-equilibrium thermodynamics. According to the standard model of cosmology, a phase transition associated with chiral symmetry breaking after the electro-weak transition has occurred when the universe was about 1–10 μs old. We focus attention on such a phase transition in the presence of a viscous relativistic cosmological background fluid in the framework of non-detailed balance Hořava–Lifshitz cosmology within an effective model of QCD. We consider a flat Friedmann–Robertson–Walker universe filled with a non-causal and a causal bulk viscous cosmological fluid respectively and investigatemore » the effects of the running coupling constants of Hořava–Lifshitz gravity, λ, on the evolution of the physical quantities relevant to a description of the early universe, namely, the temperature T, scale factor a, deceleration parameter q and dimensionless ratio of the bulk viscosity coefficient to entropy density (ξ)/s . We assume that the bulk viscosity cosmological background fluid obeys the evolution equation of the steady truncated (Eckart) and full version of the Israel–Stewart fluid, respectively. -- Highlights: •In this paper we have studied quark–hadron phase transition in the early universe in the context of the Hořava–Lifshitz model. •We use a flat FRW universe with the bulk viscosity cosmological background fluid obeying the evolution equation of the steady truncated (Eckart) and full version of the Israel–Stewart fluid, respectively.« less

Analysis of Temperature and Humidity Field in a New Bulk Tobacco Curing Barn Based on CFD.

PubMed

Bai, Zhipeng; Guo, Duoduo; Li, Shoucang; Hu, Yaohua

2017-01-31

A new structure bulk tobacco curing barn was presented. To study the temperature and humidity field in the new structure tobacco curing barn, a 3D transient computational fluid dynamics (CFD) model was developed using porous medium, species transport, κ-ε turbulence and discrete phase models. The CFD results demonstrated that (1) the temperature and relative humidity predictions were validated by the experimental results, and comparison of simulation results with experimental data showed a fairly close agreement; (2) the temperature of the bottom and inlet area was higher than the top and outlet area, and water vapor concentrated on the top and outlet area in the barn; (3) tobacco loading density and thickness of tobacco leaves had an explicit effect on the temperature distributions in the barn.

Effects of CO2 injection and Kerogen Maturation on Low-Field Nuclear Magnetic Resonance Response

NASA Astrophysics Data System (ADS)

Prasad, M.; Livo, K.

2017-12-01

Low-field Nuclear Magnetic Resonance (NMR) is commonly used in petrophysical analysis of petroleum reservoir rocks. NMR experiments record the relaxation and polarization of in-situ hydrogen protons present in gaseous phases such as free-gas intervals and solution gas fluids, bulk fluid phases such as oil and aquifer intervals, and immovable fractions of kerogen and bitumen. Analysis of NMR relaxation spectra is performed to record how fluid composition, maturity, and viscosity change NMR experimental results. We present T1-T2 maps as thermal maturity of a water-saturated, sub-mature Woodford shale is increased at temperatures from 125 to 400 degrees Celsius. Experiments with applied fluid pressure in paraffinic mineral oil and DI water with varying fluid pH have been performed to mimic reservoir conditions in analysis of the relaxation of bulk fluid phases. We have recorded NMR spectra, T1-T2 maps, and fluid diffusion coefficients using a low-field (2 MHz) MagritekTM NMR. CO2 was injected at a pressure of 900 psi in an in house developed NMR pressure vessel made of torlon plastic. Observable 2D NMR shifts in immature kerogen formations as thermal maturity is increased show generation of lighter oils with increased maturity. CO2 injection leads to a decrease in bulk fluid relaxation time that is attributed to viscosity modification with gas presence. pH variation with increased CO2 presence were shown to not effect NMR spectra. From this, fluid properties have been shown to greatly affect NMR readings and must be taken into account for more accurate NMR reservoir characterization.

Mathematical Development of the Spill Assessment Model (SAM) for Hydrazine and Similar Acting Materials in Water Bodies.

DTIC Science & Technology

1980-02-01

migration of the chemical mass in the fluid volume according to two entirely different means, yet governed by the same form of the equation: molecular ...pressure or temperature gradients, gravitational or other body forces, or bulk fluid motion, is observed as molecular diffusion. In general, the...need be made at this stage as to whether the diffusion of a released mass in the fluid is molecular or turbulent in nature. The general form of the one

Landau-de Gennes theory of surface-enhanced ordering in smectic films.

PubMed

Shalaginov, A N; Sullivan, D E

2001-03-01

A Landau theory for surface-enhanced ordering in smectic-A free-standing films is described, based on a generalization of de Gennes' model for a "presmectic" fluid confined between two walls. According to the theory, smectic ordering in free-standing films heated above the bulk smectic melting temperature is due to an intrinsic surface contribution rather than an external field. The theory yields a persistent finite-size effect, in that the film melting temperatures do not tend to the bulk transition temperature in the limit of infinite film thickness. It also predicts that a continuous transition from (N+1)- to N-layer films is impossible without an external field. The theory closely fits existing experimental data on layer-thinning transitions in compounds which exhibit a bulk smectic-A to nematic phase transition. Possible origins of the intrinsic surface contribution are discussed.

Fluid mechanics in crystal growth - The 1982 Freeman scholar lecture

NASA Technical Reports Server (NTRS)

Ostrach, S.

1983-01-01

An attempt is made to unify the current state of knowledge in crystal growth techniques and fluid mechanics. After identifying important fluid dynamic problems for such representative crystal growth processes as closed tube vapor transport, open reactor vapor deposition, and the Czochralski and floating zone melt growth techniques, research results obtained to date are presented. It is noted that the major effort to date has been directed to the description of the nature and extent of bulk transport under realistic conditions, where bulk flow determines the heat and solute transport which strongly influence the temperature and concentration fields in the vicinity of the growth interface. Proper treatment of near field, or interface, problems cannot be given until the far field, or global flow, involved in a given crystal growth technique has been adequately described.

Predicting the distribution of whey protein fouling in a plate heat exchanger using the kinetic parameters of the thermal denaturation reaction of β-lactoglobulin and the bulk temperature profiles.

PubMed

Blanpain-Avet, P; André, C; Khaldi, M; Bouvier, L; Petit, J; Six, T; Jeantet, R; Croguennec, T; Delaplace, G

2016-12-01

Fouling of plate heat exchangers (PHE) is a severe problem in the dairy industry, notably because the relationship between the build-up of protein fouling deposits and the chemical reactions taking place in the fouling solution has not yet been fully elucidated. Experiments were conducted at pilot scale in a corrugated PHE, and fouling deposits were generated using a model β-lactoglobulin (β-LG) fouling solution for which the β-LG thermal denaturation reaction constants had been previously determined experimentally. Then 18 different bulk temperature profiles within the PHE were imposed. Analysis of the fouling runs shows that the dry deposit mass per channel versus the ratio R=k unf /k agg (with k unf and k agg representing, respectively, the unfolding and aggregation rate constants computed from both the identification of the β-LG thermal denaturation process and knowledge of the imposed bulk temperature profile into the PHE channel) is able to gather reasonably well the experimental fouling mass data into a unique master curve. This type of representation of the results clearly shows that the heat-induced reactions (unfolding and aggregation) of the various β-LG molecular species in the bulk fluid are essential to capture the trend of the fouling mass distribution inside a PHE. This investigation also illustrates unambiguously that the release of the unfolded β-LG (also called β-LG molten globule) within the bulk fluid (and the absence of its consumption in the form of aggregates) is a key phenomenon that controls the extent of protein fouling as well as its location inside the PHE. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Experimental study of thermoacoustic effects on a single plate Part I: Temperature fields

NASA Astrophysics Data System (ADS)

Wetzel, M.; Herman, C.

The thermal interaction between a heated solid plate and the acoustically driven working fluid was investigated by visualizing and quantifying the temperature fields in the neighbourhood of the solid plate. A combination of holographic interferometry and high-speed cinematography was applied in the measurements. A better knowledge of these temperature fields is essential to develop systematic design methodologies for heat exchangers in oscillatory flows. The difference between heat transfer in oscillatory flows with zero mean velocity and steady-state flows is demonstrated in the paper. Instead of heat transfer from a heated solid surface to the colder bulk fluid, the visualized temperature fields indicated that heat was transferred from the working fluid into the stack plate at the edge of the plate. In the experiments, the thermoacoustic effect was visualized through the temperature measurements. A novel evaluation procedure that accounts for the influence of the acoustic pressure variations on the refractive index was applied to accurately reconstruct the high-speed, two-dimensional oscillating temperature distributions.

Solutions for the diurnally forced advection-diffusion equation to estimate bulk fluid velocity and diffusivity in streambeds from temperature time series

Treesearch

Charles H. Luce; Daniele Tonina; Frank Gariglio; Ralph Applebee

2013-01-01

Work over the last decade has documented methods for estimating fluxes between streams and streambeds from time series of temperature at two depths in the streambed. We present substantial extension to the existing theory and practice of using temperature time series to estimate streambed water fluxes and thermal properties, including (1) a new explicit analytical...

Electrical conductivity of the plagioclase-NaCl-water system and its implication for the high conductivity anomalies in the mid-lower crust of Tibet Plateau

NASA Astrophysics Data System (ADS)

Li, Ping; Guo, Xinzhuan; Chen, Sibo; Wang, Chao; Yang, Junlong; Zhou, Xingfan

2018-02-01

In order to investigate the origin of the high conductivity anomalies geophysically observed in the mid-lower crust of Tibet Plateau, the electrical conductivity of plagioclase-NaCl-water system was measured at 1.2 GPa and 400-900 K. The relationship between electrical conductivity and temperature follows the Arrhenius law. The bulk conductivity increases with the fluid fraction and salinity, but is almost independent of temperature (activation enthalpy less than 0.1 eV). The conductivity of plagioclase-NaCl-water system is much lower than that of albite-NaCl-water system with similar fluid fraction and salinity, indicating a strong effect of the major mineral phase on the bulk conductivity of the brine-bearing system. The high conductivity anomalies of 10-1 and 100 S/m observed in the mid-lower crust of Tibet Plateau can be explained by the aqueous fluid with a volume fraction of 1 and 9%, respectively, if the fluid salinity is 25%. The anomaly value of 10-1 S/m can be explained by the aqueous fluid with a volume fraction of 6% if the salinity is 10%. In case of Southern Tibet where the heat flow is high, the model of a thin layer of brine-bearing aqueous fluid with a high salinity overlying a thick layer of partial melt is most likely to prevail.

Conductivity measurements on H 2O-bearing CO 2-rich fluids

DOE PAGES

Capobianco, Ryan M.; Miroslaw S. Gruszkiewicz; Bodnar, Robert J.; ...

2014-09-10

Recent studies report rapid corrosion of metals and carbonation of minerals in contact with carbon dioxide containing trace amounts of dissolved water. One explanation for this behavior is that addition of small amounts of H 2O to CO 2 leads to significant ionization within the fluid, thus promoting reactions at the fluid-solid interface analogous to corrosion associated with aqueous fluids. The extent of ionization in the bulk CO 2 fluid was determined using a flow-through conductivity cell capable of detecting very low conductivities. Experiments were conducted from 298 to 473 K and 7.39 to 20 MPa with H 2O concentrationsmore » up to ~1600 ppmw (xH 2O ≈ 3.9 x 10 -3), corresponding to the H 2O solubility limit in liquid CO 2 at ambient temperature. All solutions showed conductivities <10 nS/cm, indicating that the solutions were essentially ion-free. Furthermore, this observation suggests that the observed corrosion and carbonation reactions are not the result of ionization in CO 2-rich bulk phase, but does not preclude ionization in the fluid at the fluid-solid interface.« less

A numerical analysis of the performance of unpumped SBE 41 sensors at low flushing rates

NASA Astrophysics Data System (ADS)

Alvarez, A.

2018-05-01

The thermal and hydrodynamic response of a Sea-Bird unpumped CTD SBE 41, is numerically modeled to assess the biases occurring at the slow flushing rates typical of glider operations. Based on symmetry considerations, the sensor response is approximated by coupling the incompressible Navier-Stokes and the thermal advection-diffusion equations in two dimensions. Numerical results illustrate three regimes in the thermal response of the SBE 41 sensor, when crossing water layers with different thermal signatures. A linear decay in time of the bulk temperature of the conductivity cell is initially found. This is induced by the transit of the inflow through the conductivity cell in the form of a relatively narrow jet. Water masses with new thermal signatures do not immediately fill the sensor chambers, where the cross-section widens. Thermal equilibrium of these water masses is then achieved, in a second regime, via a cross-flow thermal diffusion between the boundary of the jet and the walls. Consequently, the evolution of the bulk temperature scales with the square root of time. In a third regime, the evolution of the bulk temperature depends on the thermal gradient between the fluid and the coating material. This results on an exponential decay of the bulk temperature with time. A comprehensive analytical model of the time evolution of the bulk temperature inside a cell is proposed based on these results.

Thermo-hydro-mechanical coupling in long-term sedimentary rock response

NASA Astrophysics Data System (ADS)

Makhnenko, R. Y.; Podladchikov, Y.

2017-12-01

Storage of nuclear waste or CO2 affects the state of stress and pore pressure in the subsurface and may induce large thermal gradients in the rock formations. In general, the associated coupled thermo-hydro-mechanical effect on long-term rock deformation and fluid flow have to be studied. Principles behind mathematical models for poroviscoelastic response are reviewed, and poroviscous model parameter, the bulk viscosity, is included in the constitutive equations. Time-dependent response (creep) of fluid-filled sedimentary rocks is experimentally quantified at isotropic stress states. Three poroelastic parameters are measured by drained, undrained, and unjacketed geomechanical tests for quartz-rich Berea sandstone, calcite-rich Apulian limestone, and clay-rich Jurassic shale. The bulk viscosity is calculated from the measurements of pore pressure growth under undrained conditions, which requires time scales 104 s. The bulk viscosity is reported to be on the order of 1015 Pa•s for the sandstone, limestone, and shale. It is found to be decreasing with the increase of pore pressure despite corresponding decrease in the effective stress. Additionally, increase of temperature (from 24 ºC to 40 ºC) enhances creep, where the most pronounced effect is reported for the shale with bulk viscosity decrease by a factor of 3. Viscous compaction of fluid-filled porous media allows a generation of a special type of fluid flow instability that leads to formation of high-porosity, high-permeability domains that are able to self-propagate upwards due to interplay between buoyancy and viscous resistance of the deforming porous matrix. This instability is known as "porosity wave" and its formation is possible under conditions applicable to deep CO2 storage in reservoirs and explains creation of high-porosity channels and chimneys. The reported experiments show that the formation of high-permeability pathways is most likely to occur in low-permeable clay-rich materials (caprock representatives) at elevated temperatures.

Natural convection in a fluid layer periodically heated from above.

PubMed

Hossain, M Z; Floryan, J M

2014-08-01

Natural convection in a horizontal layer subject to periodic heating from above has been studied. It is shown that the primary convection leads to the cooling of the bulk of the fluid below the mean temperature of the upper wall. The secondary convection may lead either to longitudinal rolls, transverse rolls, or oblique rolls. The global flow properties (e.g., the average Nusselt number for the primary convection and the critical conditions for the secondary convection) are identical to those of the layer heated from below. However, the flow and temperature patterns exhibit phase shifts in the horizontal directions.

Changes in the Coherent Dynamics of Nanoconfined Room Temperature Ionic Liquids

NASA Astrophysics Data System (ADS)

Vallejo, Kevin; Cano, Melissa; Li, Song; Rotner, Gernot; Faraone, Antonio; Banuelos, Jose

Confinement and temperature effects on the coherent dynamics of the room temperature ionic liquid (RTIL) [C10MPy+] [Tf2N-] were investigated using neutron spin-echo (NSE) in two silica matrices with different pore size. Several intermolecular forces give rise to the bulk molecular structure between anions and cations. NSE provided dynamics (via the coherent intermediate scattering function) in the time range of 0.004 to 10 ns, and at Q-values corresponding to intermediate range ordering and inter- and intra-molecular length scales of the RTIL. Pore wall effects were delineated by comparing bulk RTIL dynamics with those of the confined fluid in 2.8 nm and 8 nm pores. Analytical models were applied to the experimental data to extract decay times and amplitudes of each component. We find a fast relaxation outside the experiment time window, a primary relaxation, and slow, surface-induced dynamics, which all speed up with increased temperature, however, the temperature dependence differs between bulk and confinement. This study sheds light on the structure and dynamics of RTILs and is relevant to the optimization of RTILs for green technologies and applications.

Is the boundary layer of an ionic liquid equally lubricating at higher temperature?

PubMed

Hjalmarsson, Nicklas; Atkin, Rob; Rutland, Mark W

2016-04-07

Atomic force microscopy has been used to study the effect of temperature on normal forces and friction for the room temperature ionic liquid (IL) ethylammonium nitrate (EAN), confined between mica and a silica colloid probe at 25 °C, 50 °C, and 80 °C. Force curves revealed a strong fluid dynamic influence at room temperature, which was greatly reduced at elevated temperatures due to the reduced liquid viscosity. A fluid dynamic analysis reveals that bulk viscosity is manifested at large separation but that EAN displays a nonzero slip, indicating a region of different viscosity near the surface. At high temperatures, the reduction in fluid dynamic force reveals step-like force curves, similar to those found at room temperature using much lower scan rates. The ionic liquid boundary layer remains adsorbed to the solid surface even at high temperature, which provides a mechanism for lubrication when fluid dynamic lubrication is strongly reduced. The friction data reveals a decrease in absolute friction force with increasing temperature, which is associated with increased thermal motion and reduced viscosity of the near surface layers but, consistent with the normal force data, boundary layer lubrication was unaffected. The implications for ILs as lubricants are discussed in terms of the behaviour of this well characterised system.

Temporal and spatial variation in porosity and compaction pressure for the viscoelastic slab

NASA Astrophysics Data System (ADS)

Morishige, M.; Van Keken, P. E.

2017-12-01

Fluid is considered to play key roles in subduction zones. It triggers various types of earthquakes by elevating pore-fluid pressure or forming hydrous minerals, and it also facilitates magma genesis by lowering the solidus temperatures of mantle and crustal rocks. Several previous numerical studies have worked on how fluid migrates and how porosity changes in time and space, but our knowledge of the fluid behavior remains limited. In this presentation, we demonstrate the detailed fluid behavior in the slab. The main features of this study are that (1) viscoelasticity is included, and that (2) fluid flow toward the inner part of the slab is also considered. We construct 2D and 3D finite element models for viscoelastic slab based on a theory of two-phase flow, which allows us to treat the movement of rock- and fluid- phases simultaneously. We solve the equations for porosity and compaction pressure which is defined as the pressure difference in between the two phases. Fluid source is fixed in time and space, and a uniform slab velocity is imposed for the whole model domain. There are several important parameters affecting the fluid behavior which includes bulk viscosity, bulk modulus, permeability, and fluid viscosity. Among these we fix bulk modulus and change the other parameters to investigate their effects on fluid migration. We find that when bulk viscosity is relatively high, elasticity is dominant and large amount of fluid is trapped in and around the fluid source. In addition, fluid migrates along the fluid source when relatively high ratio of permeability to fluid viscosity is assumed. Fluid generally moves with the slab when the ratio of permeability to fluid viscosity is low. One interesting feature is that in some cases porosity increases also in the deeper part of the fluid source due to the diffusion of compaction pressure. It suggests that the effects of resistance to volume change can be an alternative mechanism to effectively hydrate the inner part in the slab. In 3D, we find that fluid migrates in the maximum-dip direction of the slab. It leads to a fluid focusing where the slab bends away from the trench and it results in the increase in porosity and compaction pressure there. This finding may be useful to explain the observed along-arc variation in short-term slow slip events and the upper plane of double seismic zone.

Influences of the Tonga Subduction Zone on seafloor massive sulfide deposits along the Eastern Lau Spreading Center and Valu Fa Ridge

NASA Astrophysics Data System (ADS)

Evans, Guy N.; Tivey, Margaret K.; Seewald, Jeffrey S.; Wheat, C. Geoff

2017-10-01

This study investigates the morphology, mineralogy, and geochemistry of seafloor massive sulfide (SMS) deposits from six back-arc hydrothermal vent fields along the Eastern Lau Spreading Center (ELSC) and Valu Fa Ridge (VFR) in the context of endmember vent fluid chemistry and proximity to the Tonga Subduction Zone. To complement deposit geochemistry, vent fluid analyses of Cu, Zn, Ba, Pb and H2,(aq) were completed to supplement existing data and enable thermodynamic calculations of mineral saturation states at in situ conditions. Results document southward increases in the abundance of mantle-incompatible elements in hydrothermal fluids (Ba and Pb) and SMS deposits (Ba, Pb, As, and Sb), which is also expressed in the abundance of barite (BaSO4) and galena (PbS) in SMS deposits. These increases correspond to a decrease in distance between the ELSC/VFR and the Tonga Subduction Zone that correlates with a change in crustal lithology from back-arc basin basalt in the north to mixed andesite, rhyolite, and dacite in the south. Barite influences deposit morphology, contributing to the formation of horizontal flanges and squat terraces. Results are also consistent with a regional-scale lowering of hydrothermal reaction zone temperatures from north to south (except at the southernmost Mariner vent field) that leads to lower-temperature, higher-pH vent fluids relative to mid-ocean ridges of similar spreading rates (Mottl et al., 2011). These fluids are Cu- and Zn-poor and the deposits formed from these fluids are Cu-poor but Zn-rich. In contrast, at the Mariner vent field, higher-temperature and lower pH vent fluids are hypothesized to result from higher reaction zone temperatures and the localized addition of acidic magmatic volatiles (Mottl et al., 2011). The Mariner fluids are Cu- and Zn-rich and vent from SMS deposits that are rich in Cu but poor in Zn with moderate amounts of Pb. Thermodynamic calculations indicate that the contrasting metal contents of vent fluids and SMS deposits can be accounted for by vent fluid pH. Wurtzite/sphalerite ((Zn, Fe)S) and galena (PbS) are saturated at higher temperatures in higher-pH, Zn-, Cu-, and Pb-poor ELSC/VFR vent fluids, but are undersaturated at similar temperatures in low-pH, Zn-, Cu-, and Pb-rich vent fluids from the Mariner vent field. Indicators of pH in the ELSC and VFR SMS deposits include the presence of co-precipitated wurtzite and chalcopyrite along conduit linings in deposits formed from higher pH fluids, and different correlations between concentrations of Zn and Ag in bulk geochemical analyses. Significant positive bulk geochemical Zn:Ag correlations occur for deposits at vent fields where hydrothermal fluids have a minimum pH (at 25 °C) < 3.3, while correlations of Zn:Ag are weak or negative for deposits at vent fields where the minimum vent fluid pH (at 25 °C) > 3.6. Data show that the compositions of the mineral linings of open conduit chimneys (minerals present, mol% FeS in (Zn,Fe)S) that precipitate directly from hydrothermal fluids closely reflect the temperature and sulfur fugacity of sampled hydrothermal fluids. These mineral lining compositions thus can be used as indicators of hydrothermal fluid temperature and composition (pH, metal content, sulfur fugacity).

Oxygen Mass Flow Rate Generated for Monitoring Hydrogen Peroxide Stability

NASA Technical Reports Server (NTRS)

Ross, H. Richard

2002-01-01

Recent interest in propellants with non-toxic reaction products has led to a resurgence of interest in hydrogen peroxide for various propellant applications. Because peroxide is sensitive to contaminants, material interactions, stability and storage issues, monitoring decomposition rates is important. Stennis Space Center (SSC) uses thermocouples to monitor bulk fluid temperature (heat evolution) to determine reaction rates. Unfortunately, large temperature rises are required to offset the heat lost into the surrounding fluid. Also, tank penetration to accomodate a thermocouple can entail modification of a tank or line and act as a source of contamination. The paper evaluates a method for monitoring oxygen evolution as a means to determine peroxide stability. Oxygen generation is not only directly related to peroxide decomposition, but occurs immediately. Measuring peroxide temperature to monitor peroxide stability has significant limitations. The bulk decomposition of 1% / week in a large volume tank can produce in excess of 30 cc / min. This oxygen flow rate corresponds to an equivalent temperature rise of approximately 14 millidegrees C, which is difficult to measure reliably. Thus, if heat transfer were included, there would be no temperature rise. Temperature changes from the surrounding environment and heat lost to the peroxide will also mask potential problems. The use of oxygen flow measurements provides an ultra sensitive technique for monitoring reaction events and will provide an earlier indication of an abnormal decomposition when compared to measuring temperature rise.

Continuum Model of Gas Uptake for Inhomogeneous Fluids

DOE PAGES

Ihm, Yungok; Cooper, Valentino R.; Vlcek, Lukas; ...

2017-07-20

We describe a continuum model of gas uptake for inhomogeneous fluids (CMGIF) and use it to predict fluid adsorption in porous materials directly from gas-substrate interaction energies determined by first principles calculations or accurate effective force fields. The method uses a perturbation approach to correct bulk fluid interactions for local inhomogeneities caused by gas substrate interactions, and predicts local pressure and density of the adsorbed gas. The accuracy and limitations of the model are tested by comparison with the results of Grand Canonical Monte Carlo simulations of hydrogen uptake in metal-organic frameworks (MOFs). We show that the approach provides accuratemore » predictions at room temperature and at low temperatures for less strongly interacting materials. As a result, the speed of the CMGIF method makes it a promising candidate for high-throughput materials discovery in connection with existing databases of nano-porous materials.« less

A model for the influence of pressure on the bulk modulus and the influence of temperature on the solidification pressure for liquid lubricants

NASA Technical Reports Server (NTRS)

Jacobson, B. O.; Vinet, P.

1986-01-01

Two pressure chambers, for compression experiments with liquids from zero to 2.2 GPa pressure, are described. The experimentally measured compressions are then compared to theoretical values given by an isothermal model of equation of state recently introduced for solids. The model describes the pressure and bulk modulus as a function of compression for different types of lubricants with a very high accuracy up to the pressure limit of the high pressure chamber used (2.2 GPa). In addition the influence of temperature on static solidification pressure was found to be a simple function of the thermal expansion of the fluid.

Localized diffusive motion on two different time scales in solid alkane nanoparticles

NASA Astrophysics Data System (ADS)

Wang, S.-K.; Mamontov, E.; Bai, M.; Hansen, F. Y.; Taub, H.; Copley, J. R. D.; García Sakai, V.; Gasparovic, G.; Jenkins, T.; Tyagi, M.; Herwig, K. W.; Neumann, D. A.; Montfrooij, W.; Volkmann, U. G.

2010-09-01

High-energy-resolution quasielastic neutron scattering on three complementary spectrometers has been used to investigate molecular diffusive motion in solid nano- to bulk-sized particles of the alkane n-C32H66. The crystalline-to-plastic and plastic-to-fluid phase transition temperatures are observed to decrease as the particle size decreases. In all samples, localized molecular diffusive motion in the plastic phase occurs on two different time scales: a "fast" motion corresponding to uniaxial rotation about the long molecular axis; and a "slow" motion attributed to conformational changes of the molecule. Contrary to the conventional interpretation in bulk alkanes, the fast uniaxial rotation begins in the low-temperature crystalline phase.

Solar steam generation by heat localization.

PubMed

Ghasemi, Hadi; Ni, George; Marconnet, Amy Marie; Loomis, James; Yerci, Selcuk; Miljkovic, Nenad; Chen, Gang

2014-07-21

Currently, steam generation using solar energy is based on heating bulk liquid to high temperatures. This approach requires either costly high optical concentrations leading to heat loss by the hot bulk liquid and heated surfaces or vacuum. New solar receiver concepts such as porous volumetric receivers or nanofluids have been proposed to decrease these losses. Here we report development of an approach and corresponding material structure for solar steam generation while maintaining low optical concentration and keeping the bulk liquid at low temperature with no vacuum. We achieve solar thermal efficiency up to 85% at only 10 kW m(-2). This high performance results from four structure characteristics: absorbing in the solar spectrum, thermally insulating, hydrophilic and interconnected pores. The structure concentrates thermal energy and fluid flow where needed for phase change and minimizes dissipated energy. This new structure provides a novel approach to harvesting solar energy for a broad range of phase-change applications.

Investigation of Compressible Fluids for Use in soft Recoil Mechanisms

DTIC Science & Technology

1977-09-01

deNemours & Co., Wilmington, DE . A chemical formula for this material is F This particular material is available in limited stocks and is no longer being...in a dry ice bath,, transported to the laboratory, connected to the gas buret and allowed to warm to room temperature. The gas volume was measured and...their flash points are very low. The MIEL -H-5606 fluid was included here for comparison with published bulk modulus data. Another material evaluated, the

Manufacturing Solid Dosage Forms from Bulk Liquids Using the Fluid-bed Drying Technology.

PubMed

Qi, Jianping; Lu, Y I; Wu, Wei

2015-01-01

Solid dosage forms are better than liquid dosage forms in many ways, such as improved physical and chemical stability, ease of storage and transportation, improved handling properties, and patient compliance. Therefore, it is required to transform dosage forms of liquid origins into solid dosage forms. The functional approaches are to absorb the liquids by solid excipients or through drying. The conventional drying technologies for this purpose include drying by heating, vacuum-, freeze- and spray-drying, etc. Among these drying technologies, fluidbed drying emerges as a new technology that possesses unique advantages. Fluid-bed drying or coating is highly efficient in solvent removal, can be performed at relatively low temperatures, and is a one-step process to manufacture formulations in pellet forms. In this article, the status of the art of manufacturing solid dosage forms from bulk liquids by fluid-bed drying technology was reviewed emphasizing on its application in solid dispersion, inclusion complexes, self-microemulsifying systems, and various nanoscale drug delivery systems.

Methodologies for Reservoir Characterization Using Fluid Inclusion Gas Chemistry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dilley, Lorie M.

2015-04-13

The purpose of this project was to: 1) evaluate the relationship between geothermal fluid processes and the compositions of the fluid inclusion gases trapped in the reservoir rocks; and 2) develop methodologies for interpreting fluid inclusion gas data in terms of the chemical, thermal and hydrological properties of geothermal reservoirs. Phase 1 of this project was designed to conduct the following: 1) model the effects of boiling, condensation, conductive cooling and mixing on selected gaseous species; using fluid compositions obtained from geothermal wells, 2) evaluate, using quantitative analyses provided by New Mexico Tech (NMT), how these processes are recorded bymore » fluid inclusions trapped in individual crystals; and 3) determine if the results obtained on individual crystals can be applied to the bulk fluid inclusion analyses determined by Fluid Inclusion Technology (FIT). Our initial studies however, suggested that numerical modeling of the data would be premature. We observed that the gas compositions, determined on bulk and individual samples were not the same as those discharged by the geothermal wells. Gases discharged from geothermal wells are CO 2-rich and contain low concentrations of light gases (i.e. H 2, He, N, Ar, CH4). In contrast many of our samples displayed enrichments in these light gases. Efforts were initiated to evaluate the reasons for the observed gas distributions. As a first step, we examined the potential importance of different reservoir processes using a variety of commonly employed gas ratios (e.g. Giggenbach plots). The second technical target was the development of interpretational methodologies. We have develop methodologies for the interpretation of fluid inclusion gas data, based on the results of Phase 1, geologic interpretation of fluid inclusion data, and integration of the data. These methodologies can be used in conjunction with the relevant geological and hydrological information on the system to create fluid models for the system. The hope is that the methodologies developed will allow bulk fluid inclusion gas analysis to be a useful tool for estimating relative temperatures, identifying the sources and origins of the geothermal fluids, and developing conceptual models that can be used to help target areas of enhanced permeability.« less

Three-dimensional analysis for liquid hydrogen in a cryogenic storage tank with heat pipe pump system

NASA Astrophysics Data System (ADS)

Ho, Son H.; Rahman, Muhammad M.

2008-01-01

This paper presents a study on fluid flow and heat transfer of liquid hydrogen in a zero boil-off cryogenic storage tank in a microgravity environment. The storage tank is equipped with an active cooling system consisting of a heat pipe and a pump-nozzle unit. The pump collects cryogen at its inlet and discharges it through its nozzle onto the evaporator section of the heat pipe in order to prevent the cryogen from boiling off due to the heat leaking through the tank wall from the surroundings. A three-dimensional (3-D) finite element model is employed in a set of numerical simulations to solve for velocity and temperature fields of liquid hydrogen in steady state. Complex structures of 3-D velocity and temperature distributions determined from the model are presented. Simulations with an axisymmetric model were also performed for comparison. Parametric study results from both models predict that as the speed of the cryogenic fluid discharged from the nozzle increases, the mean or bulk cryogenic fluid speed increases linearly and the maximum temperature within the cryogenic fluid decreases.

Maxon and roton measurements in nanoconfined 4He

NASA Astrophysics Data System (ADS)

Bryan, M. S.; Sokol, P. E.

2018-05-01

We investigate the behavior of the collective excitations of adsorbed 4He in an ordered hexagonal mesopore, examining the crossover from a thin film to a confined fluid. Here, we present the inelastic scattering results as a function of filling at constant temperature. We find a monotonic transition of the maxon excitation as a function of filling. This has been interpreted as corresponding to an increasing density of the adsorbed helium, which approaches the bulk value as filling increases. The roton minimum exhibits a more complicated behavior that does not monotonically approach bulk values as filling increases. The full pore scattering resembles the bulk liquid accompanied by a layer mode. The maxon and roton scattering, taken together, at intermediate fillings does not correspond to a single bulk liquid dispersion at negative, low, or high pressure.

Thermal characteristics of time-periodic electroosmotic flow in a circular microchannel

NASA Astrophysics Data System (ADS)

Moghadam, Ali Jabari

2015-10-01

A theoretical analysis is performed to explore the thermal characteristics of electroosmotic flow in a circular microchannel under an alternating electric field. An analytical approach is presented to solve energy equation, and then, the exact solution of temperature profiles is obtained by using the Green's function method. This study reveals that the temperature field repeats itself for each half-period. Frequency has a strong influence on the thermal behavior of the flow field. For small values of the dimensionless frequency (small channel size, large kinematic viscosity, or small frequency), the advection mechanism is dominant in the whole domain and the resultant heating (Joule heating and wall heat flux) can be transferred by the complete flow field in the axial direction; while, the middle portion of the flow field at high dimensionless frequencies does not have sufficient time to transfer heat by advection, and the bulk fluid temperature, especially in heating, may consequently become greater than the wall temperature. In a particular instance of cooling mode, a constant surface temperature case is temporarily occurred in which the axial temperature gradient will be zero. For relatively high frequencies, the unsteady bulk fluid temperature in some radial positions at some moments may be equal to the wall temperature; hence instantaneous cylindrical surfaces with zero radial heat flux may occur over a period of time. Depending on the value and sign of the thermal scale ratio, the quasi-steady-state Nusselt number (time-averaged at one period) approaches a specific value as the electrokinetic radius becomes infinity.

Nanopore Confinement of C-O-H Fluids Relevant to Subsurface Energy Systems

NASA Astrophysics Data System (ADS)

Cole, D. R.

2016-12-01

Complex intermolecular interactions of C-O-H fluids (e.g., H2O, CO2, CH4) result in their unique thermophysical properties, including large deviations in the volumetric properties from ideality, vapor-liquid equilibria, and critical phenomena as these fluids encounter different pressure-temperature-pore network conditions in the crust. Development of a comprehensive understanding of the structures, dynamics, and reactivity at multiple length scales (molecular to macroscopic) over wide ranges of state conditions and composition is foundational to advances in quantifying geochemical processes involving mineral-fluid interfaces. The size, distribution and connectivity of these confined geometries dictate how fluids migrate into and through these micro- and nano-environments, wet and react with the solid. This presentation will provide an overview of the application of state-of-the-art experimental, analytical and computational tools to assess key features of the fluid-matrix interaction. The multidisciplinary approaches highlighted will include neutron scattering and NMR experiments, thermodynamic measurements and molecular-level simulations to quantitatively assess molecular properties of different mixtures of C-O-H fluids in nanpores. Key results include: (1) The addition of a second carbon-bearing phase or water has a profound effect on the competition for sorption sites, phase chemistry and the dynamical properties of all phases present in the pore. (2) Low solubility phases such as methane may exhibit profound increases in concentration in nanopores in the presence of water at elevated pressures and ambient temperature compared to bulk values. (3) Methane permeability through the hydrated pores is strongly dependent on the solid substrate and local properties of confined water, including its structure and, more importantly, evolution of solvation free energy and hydrogen bond structure. (4) Under certain conditions preferential adsorption of the fluids in the narrow pores can produce a shift in the equilibrium distribution of mixed volatiles present in adjoining fractures (aka the bulk portion of the system).

Stratification calculations in a heated cryogenic oxygen storage tank at zero gravity

NASA Technical Reports Server (NTRS)

Shuttles, J. T.; Smith, G. L.

1971-01-01

A cylindrical one-dimensional model of the Apollo cyrogenic oxygen storage tank has been developed to study the effect of stratification in the tank. Zero gravity was assumed, and only the thermally induced motions were considered. The governing equations were derived from conservation laws and solved on a digital computer. Realistic thermodynamic and transport properties were used. Calculations were made for a wide range of conditions. The results show the fluid behavior to be dependent on the quantity in the tank or equivalently the bulk fluid temperature. For high quantities (low temperatures) the tank pressure rose rapidly with heat addition, the heater temperature remained low, and significant pressure drop potentials accrued. For low quantities the tank pressure rose more slowly with heat addition and the heater temperature became high. A high degree of stratification resulted for all conditions; however, the stratified region extended appreciably into the tank only for the lowest tank quantity.

Numerical solution of chemically reactive non-Newtonian fluid flow: Dual stratification

NASA Astrophysics Data System (ADS)

Rehman, Khalil Ur; Malik, M. Y.; Khan, Abid Ali; Zehra, Iffat; Zahri, Mostafa; Tahir, M.

2017-12-01

We have found that only a few attempts are available in the literature relatively to the tangent hyperbolic fluid flow induced by stretching cylindrical surfaces. In particular, temperature and concentration stratification effects have not been investigated until now with respect to the tangent hyperbolic fluid model. Therefore, we have considered the tangent hyperbolic fluid flow induced by an acutely inclined cylindrical surface in the presence of both temperature and concentration stratification effects. To be more specific, the fluid flow is attained with the no slip condition, which implies that the bulk motion of the fluid particles is the same as the stretching velocity of a cylindrical surface. Additionally, the flow field situation is manifested with heat generation, mixed convection and chemical reaction effects. The flow partial differential equations give a complete description of the present problem. Therefore, to trace out the solution, a set of suitable transformations is introduced to convert these equations into ordinary differential equations. In addition, a self-coded computational algorithm is executed to inspect the numerical solution of these reduced equations. The effect logs of the involved parameters are provided graphically. Furthermore, the variations of the physical quantities are examined and given with the aid of tables. It is observed that the fluid temperature is a decreasing function of the thermal stratification parameter and a similar trend is noticed for the concentration via the solutal stratification parameter.

Convection of viscous fluids: Energetics, self-similarity, experiments, geophysical applications and analogies

NASA Technical Reports Server (NTRS)

Golitsyn, G. S.

1977-01-01

The main results were the formulas for the mean convection velocities, of a viscous fluid and for the mean temperature difference in the bulk of the convecting fluid. These were obtained: by scaling analysis of the Boussinesq equations, by analysis of the energetics of the process, and by using similarity and dimensional arguments. The last approach defines the criteria of similarity and allows the proposition of some self-similarity hypotheses. By several simple new ways, an expression for the efficiency coefficient gamma of the thermal convection was also obtained. An analogy is pointed out between non-turbulent convection of a viscous fluid and the structure of turbulence for scales less than Kolmogorov's internal viscous microscale of turbulence.

A density functional theory for colloids with two multiple bonding associating sites.

PubMed

Haghmoradi, Amin; Wang, Le; Chapman, Walter G

2016-06-22

Wertheim's multi-density formalism is extended for patchy colloidal fluids with two multiple bonding patches. The theory is developed as a density functional theory to predict the properties of an associating inhomogeneous fluid. The equation of state developed for this fluid depends on the size of the patch, and includes formation of cyclic, branched and linear clusters of associated species. The theory predicts the density profile and the fractions of colloids in different bonding states versus the distance from one wall as a function of bulk density and temperature. The predictions from our theory are compared with previous results for a confined fluid with four single bonding association sites. Also, comparison between the present theory and Monte Carlo simulation indicates a good agreement.

Influence of pH, particle size and crystal form on dissolution behaviour of engineered nanomaterials.

PubMed

Avramescu, M-L; Rasmussen, P E; Chénier, M; Gardner, H D

2017-01-01

Solubility is a critical component of physicochemical characterisation of engineered nanomaterials (ENMs) and an important parameter in their risk assessments. Standard testing methodologies are needed to estimate the dissolution behaviour and biodurability (half-life) of ENMs in biological fluids. The effect of pH, particle size and crystal form on dissolution behaviour of zinc metal, ZnO and TiO 2 was investigated using a simple 2 h solubility assay at body temperature (37 °C) and two pH conditions (1.5 and 7) to approximately frame the pH range found in human body fluids. Time series dissolution experiments were then conducted to determine rate constants and half-lives. Dissolution characteristics of investigated ENMs were compared with those of their bulk analogues for both pH conditions. Two crystal forms of TiO 2 were considered: anatase and rutile. For all compounds studied, and at both pH conditions, the short solubility assays and the time series experiments consistently showed that biodurability of the bulk analogues was equal to or greater than biodurability of the corresponding nanomaterials. The results showed that particle size and crystal form of inorganic ENMs were important properties that influenced dissolution behaviour and biodurability. All ENMs and bulk analogues displayed significantly higher solubility at low pH than at neutral pH. In the context of classification and read-across approaches, the pH of the dissolution medium was the key parameter. The main implication is that pH and temperature should be specified in solubility testing when evaluating ENM dissolution in human body fluids, even for preliminary (tier 1) screening.

Cooling beyond the boundary value in supercritical fluids under vibration

NASA Astrophysics Data System (ADS)

Sharma, D.; Erriguible, A.; Amiroudine, S.

2017-12-01

Supercritical fluids when subjected to simultaneous quench and vibration have been known to cause various intriguing flow phenomena and instabilities depending on the relative direction of temperature gradient and vibration. Here we describe a surprising and interesting phenomenon wherein temperature in the fluid falls below the imposed boundary value when the walls are quenched and the direction of vibration is normal to the temperature gradient. We define these regions in the fluid as sink zones, because they act like sink for heat within the fluid domain. The formation of these zones is first explained using a one-dimensional (1D) analysis with acceleration in constant direction. Subsequently, the effect of various boundary conditions and the relative direction of the temperature gradient to acceleration are analyzed, highlighting the necessary conditions for the formation of sink zones. It is found that the effect of high compressibility and the action of self-weight (due to high acceleration) causes the temperature to change in the bulk besides the usual action of piston effect. This subsequently affects the overall temperature profile thereby leading to the formation of sink zones. Though the examined 1D cases differ from the current two-dimensional (2D) cases, owing to the direction of acceleration being normal as compared to parallel in case of former, the explanations pertaining to 1D cases are judiciously utilized to elucidate the formation of sink zones in 2D supercritical fluids subjected to thermal quench and vibrational acceleration. The appearance of sink zones is found to be dependent on several factors such as proximity to the critical point and acceleration. A surface three-dimensional plot illustrating the effect of these parameters on onset time of sink zones is presented to further substantiate these arguments.

Thermohydrodynamic Analysis of Cryogenic Liquid Turbulent Flow Fluid Film Bearings

NASA Technical Reports Server (NTRS)

SanAndres, Luis

1996-01-01

Computational programs developed for the thermal analysis of tilting and flexure-pad hybrid bearings, and the unsteady flow and transient response of a point mass rotor supported on fluid film bearings are described. The motion of a cryogenic liquid on the thin film annular region of a fluid film bearing is described by a set of mass and momentum conservation, and energy transport equations for the turbulent bulk-flow velocities and pressure, and accompanied by thermophysical state equations for evaluation of the fluid material properties. Zeroth-order equations describe the fluid flow field for a journal static equilibrium position, while first-order (linear) equations govern the fluid flow for small amplitude-journal center translational motions. Solution to the zeroth-order flow field equations provides the bearing flow rate, load capacity, drag torque and temperature rise. Solution to the first-order equations determines the rotordynamic force coefficients due to journal radial motions.

Computer simulation of liquid-vapor coexistence of confined quantum fluids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trejos, Víctor M.; Gil-Villegas, Alejandro, E-mail: gil@fisica.ugto.mx; Martinez, Alejandro

2013-11-14

The liquid-vapor coexistence (LV) of bulk and confined quantum fluids has been studied by Monte Carlo computer simulation for particles interacting via a semiclassical effective pair potential V{sub eff}(r) = V{sub LJ} + V{sub Q}, where V{sub LJ} is the Lennard-Jones 12-6 potential (LJ) and V{sub Q} is the first-order Wigner-Kirkwood (WK-1) quantum potential, that depends on β = 1/kT and de Boer's quantumness parameter Λ=h/σ√(mε), where k and h are the Boltzmann's and Planck's constants, respectively, m is the particle's mass, T is the temperature of the system, and σ and ε are the LJ potential parameters. The non-conformalmore » properties of the system of particles interacting via the effective pair potential V{sub eff}(r) are due to Λ, since the LV phase diagram is modified by varying Λ. We found that the WK-1 system gives an accurate description of the LV coexistence for bulk phases of several quantum fluids, obtained by the Gibbs Ensemble Monte Carlo method (GEMC). Confinement effects were introduced using the Canonical Ensemble (NVT) to simulate quantum fluids contained within parallel hard walls separated by a distance L{sub p}, within the range 2σ ⩽ L{sub p} ⩽ 6σ. The critical temperature of the system is reduced by decreasing L{sub p} and increasing Λ, and the liquid-vapor transition is not longer observed for L{sub p}/σ < 2, in contrast to what has been observed for the classical system.« less

Heat transfer direction dependence of heat transfer coefficients in annuli

NASA Astrophysics Data System (ADS)

Prinsloo, Francois P. A.; Dirker, Jaco; Meyer, Josua P.

2018-04-01

In this experimental study the heat transfer phenomena in concentric annuli in tube-in-tube heat exchangers at different annular Reynolds numbers, annular diameter ratios, and inlet fluid temperatures using water were considered. Turbulent flow with Reynolds numbers ranging from 15,000 to 45,000, based on the average bulk fluid temperature was tested at annular diameter ratios of 0.327, 0.386, 0.409 and 0.483 with hydraulic diameters of 17.00, 22.98, 20.20 and 26.18 mm respectively. Both heated and cooled annuli were investigated by conducting tests at a range of inlet temperatures between 10 °C to 30 °C for heating cases, and 30 °C to 50 °C for cooling cases. Of special interest was the direct measurement of local wall temperatures on the heat transfer surface, which is often difficult to obtain and evasive in data-sets. Continuous verification and re-evaluation of temperatures measurements were performed via in-situ calibration. It is shown that inlet fluid temperature and the heat transfer direction play significant roles on the magnitude of the heat transfer coefficient. A new adjusted Colburn j-factor definition is presented to describe the heating and cooling cases and is used to correlate the 894 test cases considered in this study.

Fluid Film Bearing Code Development

NASA Technical Reports Server (NTRS)

1995-01-01

The next generation of rocket engine turbopumps is being developed by industry through Government-directed contracts. These turbopumps will use fluid film bearings because they eliminate the life and shaft-speed limitations of rolling-element bearings, increase turbopump design flexibility, and reduce the need for turbopump overhauls and maintenance. The design of the fluid film bearings for these turbopumps, however, requires sophisticated analysis tools to model the complex physical behavior characteristic of fluid film bearings operating at high speeds with low viscosity fluids. State-of-the-art analysis and design tools are being developed at the Texas A&M University under a grant guided by the NASA Lewis Research Center. The latest version of the code, HYDROFLEXT, is a thermohydrodynamic bulk flow analysis with fluid compressibility, full inertia, and fully developed turbulence models. It can predict the static and dynamic force response of rigid and flexible pad hydrodynamic bearings and of rigid and tilting pad hydrostatic bearings. The Texas A&M code is a comprehensive analysis tool, incorporating key fluid phenomenon pertinent to bearings that operate at high speeds with low-viscosity fluids typical of those used in rocket engine turbopumps. Specifically, the energy equation was implemented into the code to enable fluid properties to vary with temperature and pressure. This is particularly important for cryogenic fluids because their properties are sensitive to temperature as well as pressure. As shown in the figure, predicted bearing mass flow rates vary significantly depending on the fluid model used. Because cryogens are semicompressible fluids and the bearing dynamic characteristics are highly sensitive to fluid compressibility, fluid compressibility effects are also modeled. The code contains fluid properties for liquid hydrogen, liquid oxygen, and liquid nitrogen as well as for water and air. Other fluids can be handled by the code provided that the user inputs information that relates the fluid transport properties to the temperature.

Computation of thermodynamic and transport properties to predict thermophoretic effects in an argon-krypton mixture

NASA Astrophysics Data System (ADS)

Miller, Nicholas A. T.; Daivis, Peter J.; Snook, Ian K.; Todd, B. D.

2013-10-01

Thermophoresis is the movement of molecules caused by a temperature gradient. Here we report the results of a study of thermophoresis using non-equilibrium molecular dynamics simulations of a confined argon-krypton fluid subject to two different temperatures at thermostated walls. The resulting temperature profile between the walls is used along with the Soret coefficient to predict the concentration profile that develops across the channel. We obtain the Soret coefficient by calculating the mutual diffusion and thermal diffusion coefficients. We report an appropriate method for calculating the transport coefficients for binary systems, using the Green-Kubo integrals and radial distribution functions obtained from equilibrium molecular dynamics simulations of the bulk fluid. Our method has the unique advantage of separating the mutual diffusion and thermal diffusion coefficients, and calculating the sign and magnitude of their individual contributions to thermophoresis in binary mixtures.

Process of making cryogenically cooled high thermal performance crystal optics

DOEpatents

Kuzay, Tuncer M.

1992-01-01

A method for constructing a cooled optic wherein one or more cavities are milled, drilled or formed using casting or ultrasound laser machining techniques in a single crystal base and filled with porous material having high thermal conductivity at cryogenic temperatures. A non-machined strain-free single crystal can be bonded to the base to produce superior optics. During operation of the cooled optic, N.sub.2 is pumped through the porous material at a sub-cooled cryogenic inlet temperature and with sufficient system pressure to prevent the fluid bulk temperature from reaching saturation.

Process of making cryogenically cooled high thermal performance crystal optics

DOEpatents

Kuzay, T.M.

1992-06-23

A method is disclosed for constructing a cooled optic wherein one or more cavities are milled, drilled or formed using casting or ultrasound laser machining techniques in a single crystal base and filled with porous material having high thermal conductivity at cryogenic temperatures. A non-machined strain-free single crystal can be bonded to the base to produce superior optics. During operation of the cooled optic, N[sub 2] is pumped through the porous material at a sub-cooled cryogenic inlet temperature and with sufficient system pressure to prevent the fluid bulk temperature from reaching saturation. 7 figs.

Numerical simulation of calcium sulfate (CaSO4) fouling in the plate heat exchanger

NASA Astrophysics Data System (ADS)

Xu, Zhiming; Zhao, Yu; Han, Zhimin; Wang, Jingtao

2018-07-01

Plate heat exchanger is a widely used apparatus in the industrial production processes. Through a numerical simulation method, this paper calculates the deposition rate of CaSO4 fouling on heat transfer surfaces of the plate heat exchanger under saturation in the bulk. The effects of CaSO4 concentration in the range 0.7 kg/m3 to 1.5 kg/m3, inlet flow velocity under turbulent flow, and the fluid's inlet temperature from 288 K to 328 K on the deposition rate, removal mass rate and fouling resistance are investigated. The simulation results are compared with the experimental results showing similar trend. The simulation results show that the concentration and the flow velocity affect significantly the fouling characteristics in the plate heat exchanger. The deposition mass rate, removal mass rate, and asymptotic value of fouling resistance all increase with the increase in CaSO4 concentration and the inlet temperature of the hot fluid, while the asymptotic value of fouling resistance decreases with the increasing of inlet flow velocity. The influence of the inlet temperature of cold fluid may be negligible.

Experimental, in-situ carbon solution mechanisms and isotope fractionation in and between (C-O-H)-saturated silicate melt and silicate-saturated (C-O-H) fluid to upper mantle temperatures and pressures

NASA Astrophysics Data System (ADS)

Mysen, Bjorn

2017-02-01

Our understanding of materials transport processes in the Earth relies on characterizing the behavior of fluid and melt in silicate-(C-O-H) systems at high temperature and pressure. Here, Raman spectroscopy was employed to determine structure of and carbon isotope partitioning between melts and fluids in alkali aluminosilicate-C-O-H systems. The experimental data were recorded in-situ while the samples were at equilibrium in a hydrothermal diamond anvil cell at temperatures and pressures to 825 °C and >1300 MPa, respectively. The carbon solution equilibrium in both (C-O-H)-saturated melt and coexisting, silicate-saturated (C-O-H) fluid is 2CO3 + H2O + 2Qn + 1 = 2HCO3 + 2Qn. In the Qn-notation, the superscript, n, is the number of bridging oxygen in silicate structural units. At least one oxygen in CO3 and HCO3 groups likely is shared with silicate tetrahedra. The structural behavior of volatile components described with this equilibrium governs carbon isotope fractionation factors between melt and fluid. For example, the ΔH equals 3.2 ± 0.7 kJ/mol for the bulk 13C/12C exchange equilibrium between fluid and melt. From these experimental data, it is suggested that at deep crustal and upper mantle temperatures and pressures, the δ13C-differences between coexisting silicate-saturated (C-O-H) fluid and (C-O-H)-saturated silicate melts may change by more than 100‰ as a function of temperature in the range of magmatic processes. Absent information on temperature and pressure, the use of carbon isotopes of mantle-derived magma to derive isotopic composition of magma source regions in the Earth's interior, therefore, should be exercised with care.

Water in the presence of inert Lennard-Jones obstacles

NASA Astrophysics Data System (ADS)

Kurtjak, Mario; Urbic, Tomaz

2014-04-01

Water confined by the presence of a 'sea' of inert obstacles was examined. In the article, freely mobile two-dimensional Mercedes-Benz (MB) water put to a disordered, but fixed, matrix of Lennard-Jones disks was studied by the Monte Carlo computer simulations. For the MB water molecules in the matrix of Lennard-Jones disks, we explored the structures, hydrogen-bond-network formation and thermodynamics as a function of temperature and size and density of matrix particles. We found that the structure of model water is perturbed by the presence of the obstacles. Density of confined water, which was in equilibrium with the bulk water, was smaller than the density of the bulk water and the temperature dependence of the density of absorbed water did not show the density anomaly in the studied temperature range. The behaviour observed as a consequence of confinement is similar to that of increasing temperature, which can for a matrix lead to a process similar to capillary evaporation. At the same occupancy of space, smaller matrix molecules cause higher destruction effect on the absorbed water molecules than the bigger ones. We have also tested the hypothesis that at low matrix densities the obstacles induce an increased ordering and 'hydrogen bonding' of the MB model molecules, relative to pure fluid, while at high densities the obstacles reduce MB water structuring, as they prevent the fluid to form good 'hydrogen-bonding' networks. However, for the size of matrix molecules similar to that of water, we did not observe this effect.

Heat transfer deterioration in tubes caused by bulk flow acceleration due to thermal and frictional influences

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jackson, J. D.

2012-07-01

Severe deterioration of forced convection heat transfer can be encountered with compressible fluids flowing through strongly heated tubes of relatively small bore as the flow accelerates and turbulence is reduced because of the fluid density falling (as the temperature rises and the pressure falls due to thermal and frictional influence). The model presented here throws new light on how the dependence of density on both temperature and pressure can affect turbulence and heat transfer and it explains why the empirical equations currently available for calculating effectiveness of forced convection heat transfer under conditions of strong non-uniformity of fluid properties sometimesmore » fail to reproduce observed behaviour. It provides a criterion for establishing the conditions under which such deterioration of heat transfer might be encountered and enables heat transfer coefficients to be determined when such deterioration occurs. The analysis presented here is for a gaseous fluid at normal pressure subjected strong non-uniformity of fluid properties by the application of large temperature differences. Thus the model leads to equations which describe deterioration of heat transfer in terms of familiar parameters such as Mach number, Reynolds number and Prandtl number. It is applicable to thermal power plant systems such as rocket engines, gas turbines and high temperature gas-cooled nuclear reactors. However, the ideas involved apply equally well to fluids at supercritical pressure. Impairment of heat transfer under such conditions has become a matter of growing interest with the active consideration now being given to advanced water-cooled nuclear reactors designed to operate at pressures above the critical value. (authors)« less

Vapor-Liquid Partitioning of Iron and Manganese in Hydrothermal Fluids: An Experimental Investigation with Application to the Integrated Study of Basalt-hosted Hydrothermal Systems

NASA Astrophysics Data System (ADS)

Pester, N. J.; Seyfried, W. E.

2010-12-01

The chemistry of deep-sea hydrothermal vent fluids, expressed at the seafloor, reflects a complex history of physicochemical reactions. After three decades of field and experimental investigations, the processes of fluid-mineral equilibria that transform seawater into that of a typical “black smoker” are generally well described in the literature. Deep crustal fluids, when encountering a given heat source that ultimately drives hydrothermal circulation, routinely intersect the two-phase boundary. This process results in the nearly ubiquitous observations of variable salinity in vent fluids and is often a secondary driver of circulation via the evolution of a more buoyant (i.e. less saline) phase. Phase separation in chemically complex fluids results in the partitioning of dissolved species between the two evolved phases that deviates from simple charge balance calculations and these effects become more prominent with increasing temperature and/or decreasing pressure along the two-phase envelope. This process of partitioning has not been extensively studied and the interplay between the effects of phase separation and fluid-mineral equilibrium are not well understood. Most basalt-hosted hydrothermal systems appear to enter a steady state mode wherein fluids approach the heat source at depth and rise immediately once the two-phase boundary is met. Thus, venting fluids exhibit only modest deviations from seawater bulk salinity and the effects of partitioning are likely minor for all but the most volatile elements. Time series observations at integrated study sites, however, demonstrate dynamic changes in fluid chemistry following eruptions/magmatic events, including order of magnitude increases in gas concentrations and unexpectedly high Fe/Cl ratios. In this case, the time dependence of vapor-liquid partitioning relative to fluid-mineral equilibrium must be considered when attempting to interpret changes in subsurface reaction conditions. The two-phase region of vent fluids (as modeled by the NaCl-H2O system) represents challenging experimental conditions due to the extreme sensitivity to pressure and temperature. Using a novel flow through system that allows pressure and temperature to be controlled within 0.5 bars and 1°C, respectively, we have derived vapor-liquid partition coefficients for several species, including Fe and Mn. Divalent cations partition more drastically into the liquid phase than monovalent species and the demonstrated temperature sensitivity of equilibrium Fe/Mn ratios in basalt alteration experiments make these two elements excellent candidates when attempting to interpret time series changes in the aftermath of eruptions. Our experiments demonstrate that with decreasing vapor salinity, the Fe/Mn ratio can effectively double, relative to the bulk fluid composition, as the vapors approach the extremely low dissolved Cl concentrations observed at both EPR, 9°N and Main Endeavour, JdFR. Our results suggest that phase separation can easily account for the observed deviation from apparent Fe-Mn equilibrium in these fluids and further suggests that it may take more than a year for these hydrothermal systems to return to steady state.

Analysis of Two-Phase Flow in Damper Seals for Cryogenic Turbopumps

NASA Technical Reports Server (NTRS)

Arauz, Grigory L.; SanAndres, Luis

1996-01-01

Cryogenic damper seals operating close to the liquid-vapor region (near the critical point or slightly su-cooled) are likely to present two-phase flow conditions. Under single phase flow conditions the mechanical energy conveyed to the fluid increases its temperature and causes a phase change when the fluid temperature reaches the saturation value. A bulk-flow analysis for the prediction of the dynamic force response of damper seals operating under two-phase conditions is presented as: all-liquid, liquid-vapor, and all-vapor, i.e. a 'continuous vaporization' model. The two phase region is considered as a homogeneous saturated mixture in thermodynamic equilibrium. Th flow in each region is described by continuity, momentum and energy transport equations. The interdependency of fluid temperatures and pressure in the two-phase region (saturated mixture) does not allow the use of an energy equation in terms of fluid temperature. Instead, the energy transport is expressed in terms of fluid enthalpy. Temperature in the single phase regions, or mixture composition in the two phase region are determined based on the fluid enthalpy. The flow is also regarded as adiabatic since the large axial velocities typical of the seal application determine small levels of heat conduction to the walls as compared to the heat carried by fluid advection. Static and dynamic force characteristics for the seal are obtained from a perturbation analysis of the governing equations. The solution expressed in terms of zeroth and first order fields provide the static (leakage, torque, velocity, pressure, temperature, and mixture composition fields) and dynamic (rotordynamic force coefficients) seal parameters. Theoretical predictions show good agreement with experimental leakage pressure profiles, available from a Nitrogen at cryogenic temperatures. Force coefficient predictions for two phase flow conditions show significant fluid compressibility effects, particularly for mixtures with low mass content of vapor. Under these conditions, an increase on direct stiffness and reduction of whirl frequency ratio are shown to occur. Prediction of such important effects will motivate experimental studies as well as a more judicious selection of the operating conditions for seals used in cryogenic turbomachinery.

Measurement of the Specific Heat Using a Gravity Cancellation Approach

NASA Technical Reports Server (NTRS)

Zhong, Fang

2003-01-01

The specific heat at constant volume C(sob V) of a simple fluid diverges near its liquid-vapor critical point. However, gravity-induced density stratification due to the divergence of isothermal susceptibility hinders the direct comparison of the experimental data with the predictions of renormalization group theory. In the past, a microgravity environment has been considered essential to eliminate the density stratification. We propose to perform specific heat measurements of He-3 on the ground using a method to cancel the density stratification. A He-3 fluid layer will be heated from below, using the thermal expansion of the fluid to cancel the hydrostatic compression. A 6% density stratification at a reduced temperature of 10(exp -5) can be cancelled to better than 0.1% with a steady 1.7 micro K temperature difference across a 0.05 cm thick fluid layer. A conventional AC calorimetry technique will be used to determine the heat capacity. The minimized bulk density stratification with a relaxation time 6500 sec at a reduced temperature of 10(exp -5) will stay unchanged during 1 Hz AC heating. The smear of the specific heat divergence due to the temperature difference across the cell is about 0.1% at a reduced temperature of 10(exp -6). The combination of using High Resolution Thermometry with a 0.5 n K temperature resolution in the AC technique and the cancellation of the density stratification will enable C(sub V) to be measured down to a reduced temperature of 10(exp -6) with less than a 1% systematic error.

Substantial reduction of the heat losses to ambient air by natural convection from horizontal in-tube flows: impact of an axial bundle of passive baffles

NASA Astrophysics Data System (ADS)

Campo, A.; Cortés, C.

This paper is concerned with a distinct and effective technique to insulate horizontal tubes carrying hot fluids without using the variety of insulating materials traditionally utilized in industry. The tubes transport hot fluids and are exposed to a natural convection environment of air at standard atmospheric temperature and pressure. Essentially, an ``equivalent quantity of insulation'' is provided by an envelope of straight symmetric baffles made from a low conductivity material that is affixed to the outer surface of the horizontal tubes. A simple 1-D lumped model of comparable precision to the customary 2-D differential model serves to regulate the thermal interaction between the two perpendicular fluid streams, one horizontal due to internal forced convection and the other vertical due to external natural convection in air. All computations are algebraic and lead to a rapid determination of the two quantities that are indispensable to design engineers: the mean bulk temperatures of the internal hot fluid moving either laminarly or turbulently, together with the degraded levels of heat transfer rates.

Molecular modeling the microstructure and phase behavior of bulk and inhomogeneous complex fluids

NASA Astrophysics Data System (ADS)

Bymaster, Adam

Accurate prediction of the thermodynamics and microstructure of complex fluids is contingent upon a model's ability to capture the molecular architecture and the specific intermolecular and intramolecular interactions that govern fluid behavior. This dissertation makes key contributions to improving the understanding and molecular modeling of complex bulk and inhomogeneous fluids, with an emphasis on associating and macromolecular molecules (water, hydrocarbons, polymers, surfactants, and colloids). Such developments apply broadly to fields ranging from biology and medicine, to high performance soft materials and energy. In the bulk, the perturbed-chain statistical associating fluid theory (PC-SAFT), an equation of state based on Wertheim's thermodynamic perturbation theory (TPT1), is extended to include a crossover correction that significantly improves the predicted phase behavior in the critical region. In addition, PC-SAFT is used to investigate the vapor-liquid equilibrium of sour gas mixtures, to improve the understanding of mercaptan/sulfide removal via gas treating. For inhomogeneous fluids, a density functional theory (DFT) based on TPT1 is extended to problems that exhibit radially symmetric inhomogeneities. First, the influence of model solutes on the structure and interfacial properties of water are investigated. The DFT successfully describes the hydrophobic phenomena on microscopic and macroscopic length scales, capturing structural changes as a function of solute size and temperature. The DFT is used to investigate the structure and effective forces in nonadsorbing polymer-colloid mixtures. A comprehensive study is conducted characterizing the role of polymer concentration and particle/polymer size ratio on the structure, polymer induced depletion forces, and tendency towards colloidal aggregation. The inhomogeneous form of the association functional is used, for the first time, to extend the DFT to associating polymer systems, applicable to any association scheme. Theoretical results elucidate how reversible bonding governs the structure of a fluid near a surface and in confined environments, the molecular connectivity (formation of supramolecules, star polymers, etc.) and the phase behavior of the system. Finally, the DFT is extended to predict the inter- and intramolecular correlation functions of polymeric fluids. A theory capable of providing such local structure is important to understanding how local chemistry, branching, and bond flexibility affect the thermodynamic properties of polymers.

Critical point wetting drop tower experiment

NASA Technical Reports Server (NTRS)

Kaukler, William F.

1990-01-01

The 100 m Drop Tower at NASA-Marshall was used to provide the step change in acceleration from 1.0 to 0.0005 g. An inter-fluid meniscus oscillates vertically within a cylindrical container when suddenly released from earth's gravity and taken into a microgravity environment. Oscillations damp out from energy dissipative mechanisms such as viscosity and interfacial friction. Damping of the oscillations by the later mechanism is affected by the nature of the interfacial junction between the fluid-fluid interface and the container wall. In earlier stages of the project, the meniscus shape which developed during microgravity conditions was applied to evaluations of wetting phenomena near the critical temperature. Variations in equilibrium contact angle against the container wall were expected to occur under critical wetting conditions. However, it became apparent that the meaningful phenomenon was the damping of interfacial oscillations. This latter concept makes up the bulk of this report. Perfluoromethyl cyclohexane and isopropanol in glass were the materials used for the experiment. The wetting condition of the fluids against the wall changes at the critical wetting transition temperature. This change in wetting causes a change in the damping characteristics of the interfacial excursions during oscillation and no measurable change in contact angle. The effect of contact line friction measured above and below the wetting transition temperature was to increase the period of vertical oscillation for the vapor-liquid interface when below the wetting transition temperature.

Effect of pore geometry on the compressibility of a confined simple fluid

NASA Astrophysics Data System (ADS)

Dobrzanski, Christopher D.; Maximov, Max A.; Gor, Gennady Y.

2018-02-01

Fluids confined in nanopores exhibit properties different from the properties of the same fluids in bulk; among these properties is the isothermal compressibility or elastic modulus. The modulus of a fluid in nanopores can be extracted from ultrasonic experiments or calculated from molecular simulations. Using Monte Carlo simulations in the grand canonical ensemble, we calculated the modulus for liquid argon at its normal boiling point (87.3 K) adsorbed in model silica pores of two different morphologies and various sizes. For spherical pores, for all the pore sizes (diameters) exceeding 2 nm, we obtained a logarithmic dependence of fluid modulus on the vapor pressure. Calculation of the modulus at saturation showed that the modulus of the fluid in spherical pores is a linear function of the reciprocal pore size. The calculation of the modulus of the fluid in cylindrical pores appeared too scattered to make quantitative conclusions. We performed additional simulations at higher temperature (119.6 K), at which Monte Carlo insertions and removals become more efficient. The results of the simulations at higher temperature confirmed both regularities for cylindrical pores and showed quantitative difference between the fluid moduli in pores of different geometries. Both of the observed regularities for the modulus stem from the Tait-Murnaghan equation applied to the confined fluid. Our results, along with the development of the effective medium theories for nanoporous media, set the groundwork for analysis of the experimentally measured elastic properties of fluid-saturated nanoporous materials.

Magma genesis at Gale Crater: Evidence for Pervasive Mantle Metasomatism

NASA Astrophysics Data System (ADS)

Filiberto, J.

2017-12-01

Basaltic rocks have been analyzed at Gale Crater with a larger range in bulk chemistry than at any other landing site [1]. Therefore, the rocks may have experienced significantly different formation conditions than those experienced by magmas at Gusev Crater or Meridiani Planum. Specifically, the rocks at Gale Crater have higher potassium than other Martian rocks, with a potential analog of the Nakhlite parental magma, and are consistent with forming from a metasomatized mantle source [2-4]. Mantle metasomatism would not only affect the bulk chemistry but mantle melting conditions, as metasomatism fluxes fluids into the source region. Here I will combine differences in bulk chemistry between Martian basalts to calculate formation conditions in the interior and investigate if the rocks at Gale Crater experienced magma genesis conditions consistent with metasomatism - lower temperatures and pressures of formation. To calculate average formation conditions, I rely on experimental results, where available, and silica-activity and Mg-exchange thermometry calculations for all other compositions following [5, 6]. The results show that there is a direct correlation between the calculated mantle potential temperature and the K/Ti ratio of Gale Crater rocks. This is consistent with fluid fluxed metasomatism introducing fluids to the system, which depressed the melting temperature and fluxed K but not Ti to the system. Therefore, all basalts at Gale Crater are consistent with forming from a metasomatized mantle source, which affected not only the chemistry of the basalts but also the formation conditions. References: [1] Cousin A. et al. (2017) Icarus. 288: 265-283. [2] Treiman A.H. et al. (2016) Journal of Geophysical Research: Planets. 121: 75-106. [3] Treiman A.H. and Medard E. (2016) Geological Society of America Abstracts with Programs. 48: doi: 10.1130/abs/2016AM-285851. [4] Schmidt M.E. et al. (2016) Geological Society of America Abstracts with Programs. 48: doi: 10.1130/abs/2016AM-285651. [5] Filiberto J. and Dasgupta R. (2011) Earth and Planetary Science Letters. 304: 527-537. [6] Filiberto J. and Dasgupta R. (2015) Journal of Geophysical Research: Planets. 120: DOI: 10.1002/2014JE004745.

Genesis of the Sb-W-Au deposits at Ixtahuacan, Guatemala: evidence from fluid inclusions and stable isotopes

NASA Astrophysics Data System (ADS)

Guillemette, N.; Williams-Jones, A. E.

1993-06-01

The Ixtahuacan Sb-W deposits are hosted by upper Pennsylvanian to Permian metasedimentary rocks of the central Cordillera of Guatemala. The deposits consist of gold-bearing arsenopyrite, stibnite and scheelite. Arsenopyrite and scheelite are early in the paragenesis, occurring as disseminations in pyritiferous black shale/sandstone and in argillaceous limestone, respectively. Some stibnite is disseminated, but the bulk of the stibnite occurs as massive stratabound lenses in black shales and in quartz-ankerite veins and breccias, locally containing scheelite. Microthermometric measurements on fluid inclusions in quartz and scheelite point to a low temperature (160 190°C) and low to moderate salinity (5 15 wt% NaCl eq.) aqueous ore fluid. Abundant vapour-rich inclusions suggest that the fluid boiled. Carbon dioxide was produced locally as a result of interaction of the aqueous fluid with the argillaceous limestone. Bulk leaching experiments and SEM-EDS analyses of decrepitated fluid inclusion residues indicate that the ore-bearing solution was NaCl-dominated. The δ18O values of quartz, ankerite and scheelite from mineralized veins range from 19.7 to 20.5‰, 18.1 to 20.0‰ and 7.0 to 8.4‰ respectively. The average temperature calculated from quartz-scheelite oxygen isotopic fractionation is 170°C. The oxygen isotopic composition of the fluid, interpreted to have been in equilibrium with these minerals, ranged from 5.7 to 7.6‰, and is considered to represent an evolved meteoric water. Diagenetic or syngenetic pyrite has a sulphur isotopic composition of 0.5±0.3‰ which is consistent with bacterial reduction of sulphate. The δ34S values of arsenopyrite and stibnite range from -2.8 to 2.0‰ and -2.7 to -2.3‰ respectively, and are though to reflect sulphur derived from pyrite. The Ixtahuacan deposits are interpreted to have formed at low temperature (<200°C) and a depth of a few hundred metres from a low fO2 (10-49-10-57), high pH (7 8) fluid. Arsenic was probably transported as arsenious acid, antimony and gold as thio-complexes and tungsten as the complex HWO{4/-}. A model is proposed in which a meteoric fluid, heated by a felsic intrusion at depth, was focused to shallow levels along faults. The interaction of the fluid with pyritiferous beds caused the deposition of arsenopyrite as a result of sulphidation and/or decreasing fO2; gold probably co-precipitated with As or was adsorbed onto the arsenopyrite. The precipitation of stibnite was caused by boiling. Scheelite deposited in response to the increase in Ca2+ activity which accompanied interaction of the ore fluid with the argillaceous limestones.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Das, Chandan K.; Singh, Jayant K., E-mail: jayantks@iitk.ac.in

Three-stage pseudo-supercritical transformation path and multiple-histogram reweighting technique are employed for the determination of solid-liquid coexistence of the Lennard-Jones (12-6) fluid, in a structureless cylindrical pore of radius, R, ranging from 4 to 20 molecular diameters. The Gibbs free energy difference is evaluated using thermodynamic integration method by connecting solid and liquid phases under confinement via one or more intermediate states without any first order phase transition among them. The thermodynamic melting temperature, T{sub m}, is found to oscillate for pore size, R < 8, which is in agreement with the behavior observed for the melting temperature in slit pores.more » However, T{sub m} for almost all pore sizes is less than the bulk case, which is contrary to the behavior seen for the slit pore. The oscillation in T{sub m} decays at around pore radius R = 8, and beyond that shift in the melting temperature with respect to the bulk case is in line with the prediction of the Gibbs-Thomson equation.« less

Understanding physical rock properties and their relation to fluid-rock interactions under supercritical conditions

NASA Astrophysics Data System (ADS)

Kummerow, Juliane; Raab, Siegfried; Meyer, Romain

2017-04-01

The electrical conductivity of rocks is, in addition to lithological factors (mineralogy, porosity) and physical parameters (temperature, pressure) sensitive to the nature of pore fluids (phase, salinity), and thus may be an indicative measure for fluid-rock interactions. Especially near the critical point, which is at 374.21° C and 22.12 MPa for pure water, the physico-chemical properties of aqueous fluids change dramatically and mass transfer and diffusion-controlled chemical reactivity are enhanced, which in turn leads to the formation of element depletion/ enrichment patterns or cause mineral dissolution. At the same time, the reduction of the dielectric constant of water promotes ion association and consequently mineral precipitation. All this cause changes in the electrical conductivity of geothermal fluids and may have considerable effects on the porosity and hydraulic properties of the rocks with which they are in contact. In order to study the impact of fluid-rock interactions on the physical properties of fluids and rocks in near- and supercritical geological settings in more detail, in the framework of the EU-funded project "IMAGE" (Integrated Methods for Advanced Geothermal Exploration) hydraulic and electrical properties of rock cores from different active and exhumed geothermal areas on Iceland were measured up to supercritical conditions (Tmax = 380° C, pfluid = 23 MPa) during long-term (2-3 weeks) flow-through experiments in an internally heated gas pressure vessel at a maximum confining pressure of 42 MPa. In a second flow-through facility both the intrinsic T-dependent electrical fluid properties as well as the effect of mineral dissolution/ precipitation on the fluid conductivity were measured for increasing temperatures in a range of 24 - 422° C at a constant fluid pressure of 31 MPa. Petro- and fluid physical measurements were supplemented by a number of additional tests, comprising microstructural investigations as well as the chemical analysis of fluid samples, which were taken at every temperature level. Both physical and chemical data indicate only slight fluid-rock interactions at T < 250° C and the increase in bulk conductivity is most probably dominated by a T-dependence of the surface conductance. At higher temperatures, the decreasing fluid density causes the decrease of dielectric constant, which in turn leads to the precipitation of minerals due to a promoted association between oppositely charged ions. This is intensified at the critical point, indicated by a sharp decrease in conductivity, when regarding pure fluids. The opposite was observed in experiments, where fluid-solid interaction was allowed. In this case, the conductivity of the bulk system has increased within seconds nearly by factor 7. This points to a massive release of charge carriers due to an extensive and spontaneous increase in rock solubility, what counterbalances the effect of mineral precipitation. Moreover, the permanent oscillation of conductivities at supercritical conditions may indicate a dynamic interplay of ion depletion by mineral precipitation and the input of new charge carriers due to mineral dissolution. Regarding the permeability we can resolve the influence of mineral precipitation only, which is indicated by a decrease in rock permeability by about 5 % after the sample was exposed to supercritical conditions for 4 hours. Especially, for Si a continuous increase of ion concentration in the fluid samples is revealed for increasing temperatures, indicating a beginning mineral dissolution above 150° C. At near-critical conditions also Al and Pb as well as the rare earth elements (REE) are more intensively dissolved. From SEM analyses it is apparent that the alteration of the solid material is most effective where fresh fluid is continuously flowing around the solid, while stagnant fluids led to a much less pervasive alteration of the material. In this case, solid dissolution seems to slow down considerably or even comes to an end, what can be explained by the adjustment of a chemical equilibrium and the stabilisation of the reaction front.

Smoothed dissipative particle dynamics model for mesoscopic multiphase flows in the presence of thermal fluctuations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lei, Huan; Baker, Nathan A.; Wu, Lei

2016-08-05

Thermal fluctuations cause perturbations of fluid-fluid interfaces and highly nonlinear hydrodynamics in multiphase flows. In this work, we develop a novel multiphase smoothed dissipative particle dynamics model. This model accounts for both bulk hydrodynamics and interfacial fluctuations. Interfacial surface tension is modeled by imposing a pairwise force between SDPD particles. We show that the relationship between the model parameters and surface tension, previously derived under the assumption of zero thermal fluctuation, is accurate for fluid systems at low temperature but overestimates the surface tension for intermediate and large thermal fluctuations. To analyze the effect of thermal fluctuations on surface tension,more » we construct a coarse-grained Euler lattice model based on the mean field theory and derive a semi-analytical formula to directly relate the surface tension to model parameters for a wide range of temperatures and model resolutions. We demonstrate that the present method correctly models the dynamic processes, such as bubble coalescence and capillary spectra across the interface.« less

Multiple stable isotope fronts during non-isothermal fluid flow

NASA Astrophysics Data System (ADS)

Fekete, Szandra; Weis, Philipp; Scott, Samuel; Driesner, Thomas

2018-02-01

Stable isotope signatures of oxygen, hydrogen and other elements in minerals from hydrothermal veins and metasomatized host rocks are widely used to investigate fluid sources and paths. Previous theoretical studies mostly focused on analyzing stable isotope fronts developing during single-phase, isothermal fluid flow. In this study, numerical simulations were performed to assess how temperature changes, transport phenomena, kinetic vs. equilibrium isotope exchange, and isotopic source signals determine mineral oxygen isotopic compositions during fluid-rock interaction. The simulations focus on one-dimensional scenarios, with non-isothermal single- and two-phase fluid flow, and include the effects of quartz precipitation and dissolution. If isotope exchange between fluid and mineral is fast, a previously unrecognized, significant enrichment in heavy oxygen isotopes of fluids and minerals occurs at the thermal front. The maximum enrichment depends on the initial isotopic composition of fluid and mineral, the fluid-rock ratio and the maximum change in temperature, but is independent of the isotopic composition of the incoming fluid. This thermally induced isotope front propagates faster than the signal related to the initial isotopic composition of the incoming fluid, which forms a trailing front behind the zone of transient heavy oxygen isotope enrichment. Temperature-dependent kinetic rates of isotope exchange between fluid and rock strongly influence the degree of enrichment at the thermal front. In systems where initial isotope values of fluids and rocks are far from equilibrium and isotope fractionation is controlled by kinetics, the temperature increase accelerates the approach of the fluid to equilibrium conditions with the host rock. Consequently, the increase at the thermal front can be less dominant and can even generate fluid values below the initial isotopic composition of the input fluid. As kinetics limit the degree of isotope exchange, a third front may develop in kinetically limited systems, which propagates with the advection speed of the incoming fluid and is, therefore, traveling fastest. The results show that oxygen isotope signatures at thermal fronts recorded in rocks and veins that experienced isotope exchange with fluids can easily be misinterpreted, namely if bulk analytical techniques are applied. However, stable isotope microanalysis on precipitated minerals may - if later isotope exchange is kinetically limited - provide a valuable archive of the transient thermal and hydrological evolution of a system.

Effect of Interfacial Turbulence and Accommodation Coefficient on CFD Predictions of Pressurization and Pressure Control in Cryogenic Storage Tank

NASA Technical Reports Server (NTRS)

Kassemi, Mohammad; Kartuzova, Olga; Hylton, Sonya

2015-01-01

Laminar models agree closely with the pressure evolution and vapor phase temperature stratification but under-predict liquid temperatures. Turbulent SST k-w and k-e models under-predict the pressurization rate and extent of stratification in the vapor but represent liquid temperature distributions fairly well. These conclusions seem to equally apply to large cryogenic tank simulations as well as small scale simulant fluid pressurization cases. Appropriate turbulent models that represent both interfacial and bulk vapor phase turbulence with greater fidelity are needed. Application of LES models to the tank pressurization problem can serve as a starting point.

Dormancy and Recovery Testing for Biological Wastewater Processors

NASA Technical Reports Server (NTRS)

Hummerick, Mary E.; Coutts, Janelle L.; Lunn, Griffin M.; Spencer, LaShelle; Khodadad, Christina L.; Birmele, Michele N.; Frances, Someliz; Wheeler, Raymond

2015-01-01

Bioreactors, such as the aerated hollow fiber membrane type, have been proposed and studied for a number of years as an alternate approach for treating wastewater streams for space exploration. Several challenges remain to be resolved before these types of bioreactors can be used in space settings, including transporting the bioreactors with intact and active biofilms, whether that be to the International Space Station or beyond, or procedures for safing the systems and placing them into a dormant state for later start-up. Little information is available on such operations as it is not common practice for terrestrial systems. This study explored several dormancy processes for established bioreactors to determine optimal storage and recovery conditions. Procedures focused on complete isolation of the microbial communities from an operational standpoint and observing the effects of: 1) storage temperature, and 2) storage with or without the reactor bulk fluid. The first consideration was tested from a microbial integrity and power consumption standpoint; both ambient temperature (25 C) and cold (4 C) storage conditions were studied. The second consideration was explored; again, for microbial integrity as well as plausible real-world scenarios of how terrestrially established bioreactors would be transported to microgravity and stored for periods of time between operations. Biofilms were stored without the reactor bulk fluid to simulate transport of established biofilms into microgravity, while biofilms stored with the reactor bulk fluid simulated the most simplistic storage condition to implement operations for extended periods of nonuse. Dormancy condition did not have an influence on recovery in initial studies with immature biofilms (48 days old), however a lengthy recovery time was required (20+ days). Bioreactors with fully established biofilms (13 months) were able to recover from a 7-month dormancy period to steady state operation within 4 days (approx. 1 residence cycle). Results indicate a need for future testing on biofilm age and health and further exploration of dormancy length.

Dormancy and Recovery Testing for Biological Wastewater Processors

NASA Technical Reports Server (NTRS)

Hummerick, Mary E.; Coutts, Janelle L.; Lunn, Griffin M.; Spencer, LaShelle; Khodadad, Christina L.; Frances, Someliz; Wheller, Raymond

2015-01-01

Bioreactors, such as aerated membrane type bioreactors have been proposed and studied for a number of years as an alternate approach for treating wastewater streams for space exploration. Several challenges remain before these types of bioreactors can be used in space settings, including transporting the bioreactors with their microbial communities to space, whether that be the International Space Station or beyond, or procedures for safing the systems and placing them into dormant state for later start-up. Little information is available on such operations as it is not common practice for terrestrial systems. This study explored several dormancy processes for established bioreactors to determine optimal storage and recovery conditions. Procedures focused on complete isolation of the microbial communities from an operational standpoint and observing the effects of: 1) storage temperature, and 2) storage with or without the reactor bulk fluid. The first consideration was tested from a microbial integrity and power consumption standpoint; both room temperature (25 C) and cold (4 C) storage conditions were studied. The second consideration was explored; again, for microbial integrity as well as plausible real-world scenarios of how terrestrially established bioreactors would be transported to microgravity and stored for periods of time between operations. Biofilms were stored without the reactor bulk fluid to simulate transport of established biofilms into microgravity, while biofilms stored with the reactor bulk fluid simulated the most simplistic storage condition to implement operations for extended periods of nonuse. Dormancy condition did not have an influence on recovery in initial studies with immature biofilms (48 days old), however, a lengthy recovery time was required (20+ days). Bioreactors with fully established biofilms (13 months) were able to recover from a 7-month dormancy period to steady state operation within 4 days (approximately 1 residence cycle). Results indicate a need for future testing on biofilm age and health and further exploration of dormancy length.

Characteristics of heat transfer fouling of thin stillage using model thin stillage and evaporator concentrates

NASA Astrophysics Data System (ADS)

Challa, Ravi Kumar

The US fuel ethanol demand was 50.3 billion liters (13.3 billion gallons) in 2012. Corn ethanol was produced primarily by dry grind process. Heat transfer equipment fouling occurs during corn ethanol production and increases the operating expenses of ethanol plants. Following ethanol distillation, unfermentables are centrifuged to separate solids as wet grains and liquid fraction as thin stillage. Evaporator fouling occurs during thin stillage concentration to syrup and decreases evaporator performance. Evaporators need to be shutdown to clean the deposits from the evaporator surfaces. Scheduled and unscheduled evaporator shutdowns decrease process throughput and results in production losses. This research were aimed at investigating thin stillage fouling characteristics using an annular probe at conditions similar to an evaporator in a corn ethanol production plant. Fouling characteristics of commercial thin stillage and model thin stillage were studied as a function of bulk fluid temperature and heat transfer surface temperature. Experiments were conducted by circulating thin stillage or carbohydrate mixtures in a loop through the test section which consisted of an annular fouling probe while maintaining a constant heat flux by electrical heating and fluid flow rate. The change in fouling resistance with time was measured. Fouling curves obtained for thin stillage and concentrated thin stillage were linear with time but no induction periods were observed. Fouling rates for concentrated thin stillage were higher compared to commercial thin stillage due to the increase in solid concentration. Fouling rates for oil skimmed and unskimmed concentrated thin stillage were similar but lower than concentrated thin stillage at 10% solids concentration. Addition of post fermentation corn oil to commercial thin stillage at 0.5% increments increased the fouling rates up to 1% concentration but decreased at 1.5%. As thin stillage is composed of carbohydrates, protein, lipid, fiber and minerals, simulated thin stillage was prepared with carbohydrate mixtures and tested for fouling rates. Induction period, maximum fouling resistance and mean fouling rates were determined. Two experiments were performed with two varieties of starch, waxy and high amylose and short chain carbohydrates, corn syrup solids and glucose. Interaction effects of glucose with starch varieties were studied. In the first experiment, short chain carbohydrates individual and interaction effects with starch were studied. For mixtures prepared from glucose and corn syrup solids, no fouling was observed. Mixtures prepared from starch, a long glucose polymer, showed marked fouling. Corn syrup solids and glucose addition to pure starch decreased the mean fouling rates and maximum fouling resistances. Between corn syrup solids and glucose, starch fouling rates were reduced with addition of glucose. Induction periods of pure mixtures of either glucose or corn syrup solids were longer than the test period (5 h). Pure starch mixture had no induction period. Maximum fouling resistance was higher for mixtures with higher concentration of longer polymers. Waxy starch had a longer induction period than high amylose starch. Maximum fouling resistance was higher for waxy than high amylose starch. Addition of glucose to waxy or high amylose starch increased induction period of mixtures longer than 5 h test period. It appears that the bulk fluid temperature plays an important role on carbohydrate mixture fouling rates. Higher bulk fluid temperatures increased the initial fouling rates of the carbohydrate mixtures. Carbohydrate type, depending on the polymer length, influenced the deposit formation. Longer chain carbohydrate, starch, had higher fouling rates compared to shorter carbohydrates such as glucose and corn syrup solids. For insoluble carbohydrate mixtures, fouling was severe. As carbohydrate solubility increased with bulk fluid temperature, surface reaction increased at probe surface and resulted in deposit formation. Higher surface temperatures eliminated induction periods for thin stillage and fouling was rapid on probe surface.

Molecular mechanics and structure of the fluid-solid interface in simple fluids

NASA Astrophysics Data System (ADS)

Wang, Gerald J.; Hadjiconstantinou, Nicolas G.

2017-09-01

Near a fluid-solid interface, the fluid spatial density profile is highly nonuniform at the molecular scale. This nonuniformity can have profound effects on the dynamical behavior of the fluid and has been shown to play an especially important role when modeling a wide variety of nanoscale heat and momentum transfer phenomena. We use molecular-mechanics arguments and molecular-dynamics (MD) simulations to develop a better understanding of the structure of the first fluid layer directly adjacent to the solid in the layering regime, as delineated by a nondimensional number that compares the effects of wall-fluid interaction to thermal energy. Using asymptotic analysis of the Nernst-Planck equation, we show that features of the fluid density profile close to the wall, such as the areal density of the first layer ΣFL (defined as the number of atoms in this layer per unit of fluid-solid interfacial area), can be expressed as polynomial functions of the fluid average density ρave. This is found to be in agreement with MD simulations, which also show that the width of the first layer hFL is a linear function of the average density and only a weak function of the temperature T . These results can be combined to show that, for system average densities corresponding to a dense fluid (ρave≥0.7 ), the ratio C ≡ΣFLρavehFL, representing a density enhancement with respect to the bulk fluid, depends only weakly on temperature and is essentially independent of density. Further MD simulations suggest that the above results, nominally valid for large systems (solid in contact with semi-infinite fluid), also describe fluid-solid interfaces under considerable nanoconfinement, provided ρave is appropriately defined.

A molecular Debye-Huckel theory of solvation in polar fluids: An extension of the Born model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiao, Tiejun; Song, Xueyu

A dielectric response theory of solvation beyond the conventional Born model for polar fluids is presented. The dielectric response of a polar fluid is described by a Born response mode and a linear combination of Debye-Hückel-like response modes that capture the nonlocal response of polar fluids. The Born mode is characterized by a bulk dielectric constant, while a Debye-Hückel mode is characterized by its corresponding Debye screening length. Both the bulk dielectric constant and the Debye screening lengths are determined from the bulk dielectric function of the polar fluid. The linear combination coefficients of the response modes are evaluated inmore » a self-consistent way and can be used to evaluate the electrostatic contribution to the thermodynamic properties of a polar fluid. In conclusion, our theory is applied to a dipolar hard sphere fluid as well as interaction site models of polar fluids such as water, where the electrostatic contribution to their thermodynamic properties can be obtained accurately.« less

A molecular Debye-Huckel theory of solvation in polar fluids: An extension of the Born model

DOE PAGES

Xiao, Tiejun; Song, Xueyu

2017-12-06

A dielectric response theory of solvation beyond the conventional Born model for polar fluids is presented. The dielectric response of a polar fluid is described by a Born response mode and a linear combination of Debye-Hückel-like response modes that capture the nonlocal response of polar fluids. The Born mode is characterized by a bulk dielectric constant, while a Debye-Hückel mode is characterized by its corresponding Debye screening length. Both the bulk dielectric constant and the Debye screening lengths are determined from the bulk dielectric function of the polar fluid. The linear combination coefficients of the response modes are evaluated inmore » a self-consistent way and can be used to evaluate the electrostatic contribution to the thermodynamic properties of a polar fluid. In conclusion, our theory is applied to a dipolar hard sphere fluid as well as interaction site models of polar fluids such as water, where the electrostatic contribution to their thermodynamic properties can be obtained accurately.« less

A molecular Debye-Hückel theory of solvation in polar fluids: An extension of the Born model

NASA Astrophysics Data System (ADS)

Xiao, Tiejun; Song, Xueyu

2017-12-01

A dielectric response theory of solvation beyond the conventional Born model for polar fluids is presented. The dielectric response of a polar fluid is described by a Born response mode and a linear combination of Debye-Hückel-like response modes that capture the nonlocal response of polar fluids. The Born mode is characterized by a bulk dielectric constant, while a Debye-Hückel mode is characterized by its corresponding Debye screening length. Both the bulk dielectric constant and the Debye screening lengths are determined from the bulk dielectric function of the polar fluid. The linear combination coefficients of the response modes are evaluated in a self-consistent way and can be used to evaluate the electrostatic contribution to the thermodynamic properties of a polar fluid. Our theory is applied to a dipolar hard sphere fluid as well as interaction site models of polar fluids such as water, where the electrostatic contribution to their thermodynamic properties can be obtained accurately.

A molecular Debye-Hückel theory of solvation in polar fluids: An extension of the Born model.

PubMed

Xiao, Tiejun; Song, Xueyu

2017-12-07

A dielectric response theory of solvation beyond the conventional Born model for polar fluids is presented. The dielectric response of a polar fluid is described by a Born response mode and a linear combination of Debye-Hückel-like response modes that capture the nonlocal response of polar fluids. The Born mode is characterized by a bulk dielectric constant, while a Debye-Hückel mode is characterized by its corresponding Debye screening length. Both the bulk dielectric constant and the Debye screening lengths are determined from the bulk dielectric function of the polar fluid. The linear combination coefficients of the response modes are evaluated in a self-consistent way and can be used to evaluate the electrostatic contribution to the thermodynamic properties of a polar fluid. Our theory is applied to a dipolar hard sphere fluid as well as interaction site models of polar fluids such as water, where the electrostatic contribution to their thermodynamic properties can be obtained accurately.

Microgravity Transport Phenomena Experiment (MTPE) Overview

NASA Technical Reports Server (NTRS)

Mason, Larry W.

1999-01-01

The Microgravity Transport Phenomena Experiment (MTPE) is a fluids experiment supported by the Fundamentals in Biotechnology program in association with the Human Exploration and Development of Space (BEDS) initiative. The MTP Experiment will investigate fluid transport phenomena both in ground based experiments and in the microgravity environment. Many fluid transport processes are affected by gravity. Osmotic flux kinetics in planar membrane systems have been shown to be influenced by gravimetric orientation, either through convective mixing caused by unstably stratified fluid layers, or through a stable fluid boundary layer structure that forms in association with the membrane. Coupled transport phenomena also show gravity related effects. Coefficients associated with coupled transport processes are defined in terms of a steady state condition. Buoyancy (gravity) driven convection interferes with the attainment of steady state, and the measurement of coupled processes. The MTP Experiment measures the kinetics of molecular migration that occurs in fluids, in response to the application of various driving potentials. Three separate driving potentials may be applied to the MTP Experiment fluids, either singly or in combination. The driving potentials include chemical potential, thermal potential, and electrical potential. Two separate fluid arrangements are used to study membrane mediated and bulk fluid transport phenomena. Transport processes of interest in membrane mediated systems include diffusion, osmosis, and streaming potential. Bulk fluid processes of interest include coupled phenomena such as the Soret Effect, Dufour Effect, Donnan Effect, and thermal diffusion potential. MTP Experiments are performed in the Microgravity Transport Apparatus (MTA), an instrument that has been developed specifically for precision measurement of transport processes. Experiment fluids are contained within the MTA fluid cells, designed to create a one dimensional flow geometry of constant cross sectional area, and to facilitate fluid filling and draining operations in microgravity. The fluid cells may be used singly for bulk solutions, or in a Stokes diaphragm configuration to investigate membrane mediated phenomena. Thermal and electrical driving potentials are applied to the experiment fluids through boundary plates located at the ends of the fluid cells. In the ground based instrument, two constant temperature baths circulate through reservoirs adjacent to the boundary plates, and establish the thermal environment within the fluid cells. The boundary plates also serve as electrodes for measurement and application of electrical potentials. The Fluid Manipulation System associated with the MTA is a computer controlled system that enables storage and transfer of experiment fluids during on orbit operations. The system is used to automatically initiate experiments and manipulate fluids by orchestrating pump and valve operations through scripted sequences. Unique technologies are incorporated in the MTA for measurement of fluid properties. Volumetric Flow Sensors have been developed for precision measurement of total fluid volume contained within the fluid cells over time. This data is most useful for measuring the kinetics of osmosis, where fluid is transported from one fluid cell to another through a semipermeable membrane. The MicroSensor Array has been designed to perform in situ measurement of several important fluid parameters, providing simultaneous measurement of solution composition at multiple locations within the experiment fluids. Micromachined sensors and interface electronics have been developed to measure temperature, electrical conductivity, pH, cation activity, and anion activity. The Profile Refractometer uses a laser optical system to directly image the fluid Index of Refraction profile that exists along the MTA fluid cell axis. A video system acquires images of the RI profile over time, and records the transport kinetics that occur upon application of chemical, thermal, or electrical driving potentials. Image processing algorithms have been developed to analyze the refractometer images on a pixel by pixel basis, calibrating and scaling the measured Index of Refraction profile to correlated solution properties of interest such as density, concentration, and temperature. Additional software has been developed to compile the processed images into a three dimensional matrix that contains fluid composition data as a function of experiment time and position in the fluid cell. These data are combined with data from the other sensor systems, and analyzed in the context of transport coefficients associated with the various transport phenomena. Analysis protocols have been developed to measure the transient kinetics, and steady state distribution of fluid components that occur in response to the applied driving potentials. The results are expressed in terms of effective transport coefficients. Experiments have been performed using a variety of solutes, and results generated are that are in agreement with published transport coefficient values.

Melting and dissolution of subducting crust at high pressures: the key role of white mica

NASA Astrophysics Data System (ADS)

Schmidt, Max W.; Vielzeuf, Daniel; Auzanneau, Estelle

2004-11-01

Conditions of melting in the crust are generally controlled by the availability of aqueous fluid and, in the absence of fluid, by the stability of hydroxylated minerals. To depths of 80-90 km, melting is controlled by amphibole and biotite. At greater depths, both phases are unstable in crustal compositions. Simultaneous experiments on a mid-ocean ridge basalt (MORB), a greywacke, and a pelite with excess H2O of 0.4-1.4 wt.% demonstrate that, at >100 km depth (≥3.5 GPa), all three bulk compositions are composed of garnet+clinopyroxene+phengite+coesite±kyanite±rutile, phengitic white mica being the only hydrous mineral present at near-melting temperatures. At 4 GPa, melting reactions, temperatures, and initial melt compositions are thus similar in the entire subducted crust. Fluid-saturated initial melting takes place near 850 °C and melt productivities are proportional to phengite contents. All three bulk compositions produce initially slightly peraluminous potassic Si-rich granites with K:Na molar ratios of 1.4-2.0 and containing 8-13 wt.% H2O. The relatively low Na-contents of these melts result from clinopyroxene/melt partitioning coefficients (Dcpx/melt) of 2.2-4.0 at near solidus temperatures. At higher pressures (≥6.5 GPa), we infer that classical melting does not take place. Instead, the bulk H2O-contents (1.5-2.1 wt.%) in the starting materials, although low, are apparently sufficient to dissolve phengite entirely near 1050 °C. This suggests that pressure conditions beyond the singular endpoint (or second critical point) which terminates the wet solidus as defined by Ricci in 1951 [J.E. Ricci, The phase rule and heterogeneous equilibrium, Dover Publications, Inc. New York (1951) 505 p.] were reached for all three bulk compositions. Extraction of these "supercritical" solute-rich (but Na-poor) melts, which contain about 30-40% H2O, or extraction of the potassic granite melts at lower pressure leave an anhydrous garnet+clinopyroxene±coesite±kyanite±rutile residue. Our results suggest that, except for extremely cold subduction zones, the subducting crust will lose all its potassium (and most of B, Be, Rb, and Ba, and other phengite-hosted trace elements) through leaching or melting during its descent to 300 km. The potassium-rich silica-saturated liquids will immediately react with the peridotite when entering the mantle wedge thus creating source regions for ultrapotassic magmas.

Application of magnetohydrodynamic actuation to continuous flow chemistry.

PubMed

West, Jonathan; Karamata, Boris; Lillis, Brian; Gleeson, James P; Alderman, John; Collins, John K; Lane, William; Mathewson, Alan; Berney, Helen

2002-11-01

Continuous flow microreactors with an annular microchannel for cyclical chemical reactions were fabricated by either bulk micromachining in silicon or by rapid prototyping using EPON SU-8. Fluid propulsion in these unusual microchannels was achieved using AC magnetohydrodynamic (MHD) actuation. This integrated micropumping mechanism obviates the use of moving parts by acting locally on the electrolyte, exploiting its inherent conductive nature. Both silicon and SU-8 microreactors were capable of MHD actuation, attaining fluid velocities of the order of 300 microm s(-1) when using a 500 mM KCl electrolyte. The polymerase chain reaction (PCR), a thermocycling process, was chosen as an illustrative example of a cyclical chemistry. Accordingly, temperature zones were provided to enable a thermal cycle during each revolution. With this approach, fluid velocity determines cycle duration. Here, we report device fabrication and performance, a model to accurately describe fluid circulation by MHD actuation, and compatibility issues relating to this approach to chemistry.

Dynamic bulk and shear moduli due to grain-scale local fluid flow in fluid-saturated cracked poroelastic rocks: Theoretical model

NASA Astrophysics Data System (ADS)

Song, Yongjia; Hu, Hengshan; Rudnicki, John W.

2016-07-01

Grain-scale local fluid flow is an important loss mechanism for attenuating waves in cracked fluid-saturated poroelastic rocks. In this study, a dynamic elastic modulus model is developed to quantify local flow effect on wave attenuation and velocity dispersion in porous isotropic rocks. The Eshelby transform technique, inclusion-based effective medium model (the Mori-Tanaka scheme), fluid dynamics and mass conservation principle are combined to analyze pore-fluid pressure relaxation and its influences on overall elastic properties. The derivation gives fully analytic, frequency-dependent effective bulk and shear moduli of a fluid-saturated porous rock. It is shown that the derived bulk and shear moduli rigorously satisfy the Biot-Gassmann relationship of poroelasticity in the low-frequency limit, while they are consistent with isolated-pore effective medium theory in the high-frequency limit. In particular, a simplified model is proposed to quantify the squirt-flow dispersion for frequencies lower than stiff-pore relaxation frequency. The main advantage of the proposed model over previous models is its ability to predict the dispersion due to squirt flow between pores and cracks with distributed aspect ratio instead of flow in a simply conceptual double-porosity structure. Independent input parameters include pore aspect ratio distribution, fluid bulk modulus and viscosity, and bulk and shear moduli of the solid grain. Physical assumptions made in this model include (1) pores are inter-connected and (2) crack thickness is smaller than the viscous skin depth. This study is restricted to linear elastic, well-consolidated granular rocks.

Chemical reaction fouling model for single-phase heat transfer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Panchal, C.B.; Watkinson, A.P.

1993-08-01

A fouling model was developed on the premise that the chemical reaction for generation of precursor can take place in the bulk fluid, in the thermalboundary layer, or at the fluid/wall interface, depending upon the interactive effects of flu id dynamics, heat and mass transfer, and the controlling chemical reaction. The analysis was used to examine the experimental data for fouling deposition of polyperoxides produced by autoxidation of indene in kerosene. The effects of fluid and wall temperatures for two flow geometries were analyzed. The results showed that the relative effects of physical parameters on the fouling rate would differmore » for the three fouling mechanisms; therefore, it is important to identify the controlling mechanism in applying the closed-flow-loop data to industrial conditions.« less

Determination of the thermodynamic correction factor of fluids confined in nano-metric slit pores from molecular simulation

NASA Astrophysics Data System (ADS)

Collell, Julien; Galliero, Guillaume

2014-05-01

The multi-component diffusive mass transport is generally quantified by means of the Maxwell-Stefan diffusion coefficients when using molecular simulations. These coefficients can be related to the Fick diffusion coefficients using the thermodynamic correction factor matrix, which requires to run several simulations to estimate all the elements of the matrix. In a recent work, Schnell et al. ["Thermodynamics of small systems embedded in a reservoir: A detailed analysis of finite size effects," Mol. Phys. 110, 1069-1079 (2012)] developed an approach to determine the full matrix of thermodynamic factors from a single simulation in bulk. This approach relies on finite size effects of small systems on the density fluctuations. We present here an extension of their work for inhomogeneous Lennard Jones fluids confined in slit pores. We first verified this extension by cross validating the results obtained from this approach with the results obtained from the simulated adsorption isotherms, which allows to determine the thermodynamic factor in porous medium. We then studied the effects of the pore width (from 1 to 15 molecular sizes), of the solid-fluid interaction potential (Lennard Jones 9-3, hard wall potential) and of the reduced fluid density (from 0.1 to 0.7 at a reduced temperature T* = 2) on the thermodynamic factor. The deviation of the thermodynamic factor compared to its equivalent bulk value decreases when increasing the pore width and becomes insignificant for reduced pore width above 15. We also found that the thermodynamic factor is sensitive to the magnitude of the fluid-fluid and solid-fluid interactions, which softens or exacerbates the density fluctuations.

Determination of the thermodynamic correction factor of fluids confined in nano-metric slit pores from molecular simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Collell, Julien; Galliero, Guillaume, E-mail: guillaume.galliero@univ-pau.fr

2014-05-21

The multi-component diffusive mass transport is generally quantified by means of the Maxwell-Stefan diffusion coefficients when using molecular simulations. These coefficients can be related to the Fick diffusion coefficients using the thermodynamic correction factor matrix, which requires to run several simulations to estimate all the elements of the matrix. In a recent work, Schnell et al. [“Thermodynamics of small systems embedded in a reservoir: A detailed analysis of finite size effects,” Mol. Phys. 110, 1069–1079 (2012)] developed an approach to determine the full matrix of thermodynamic factors from a single simulation in bulk. This approach relies on finite size effectsmore » of small systems on the density fluctuations. We present here an extension of their work for inhomogeneous Lennard Jones fluids confined in slit pores. We first verified this extension by cross validating the results obtained from this approach with the results obtained from the simulated adsorption isotherms, which allows to determine the thermodynamic factor in porous medium. We then studied the effects of the pore width (from 1 to 15 molecular sizes), of the solid-fluid interaction potential (Lennard Jones 9-3, hard wall potential) and of the reduced fluid density (from 0.1 to 0.7 at a reduced temperature T* = 2) on the thermodynamic factor. The deviation of the thermodynamic factor compared to its equivalent bulk value decreases when increasing the pore width and becomes insignificant for reduced pore width above 15. We also found that the thermodynamic factor is sensitive to the magnitude of the fluid-fluid and solid-fluid interactions, which softens or exacerbates the density fluctuations.« less

Sorption Phase of Supercritical CO2 in Silica Aerogel: Experiments and Mesoscale Computer Simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rother, Gernot; Vlcek, Lukas; Gruszkiewicz, Miroslaw

2014-01-01

Adsorption of supercritical CO2 in nanoporous silica aerogel was investigated by a combination of experiments and molecular-level computer modeling. High-pressure gravimetric and vibrating tube densimetry techniques were used to measure the mean pore fluid density and excess sorption at 35 C and 50 C and pressures of 0-200 bar. Densification of the pore fluid was observed at bulk fluid densities below 0.7 g/cm3. Far above the bulk fluid density, near-zero sorption or weak depletion effects were measured, while broad excess sorption maxima form in the vicinity of the bulk critical density region. The CO2 sorption properties are very similar formore » two aerogels with different bulk densities of 0.1 g/cm3 and 0.2 g/cm3, respectively. The spatial distribution of the confined supercritical fluid was analyzed in terms of sorption- and bulk-phase densities by means of the Adsorbed Phase Model (APM), which used data from gravimetric sorption and small-angle neutron scattering experiments. To gain more detailed insight into supercritical fluid sorption, large-scale lattice gas GCMC simulations were utilized and tuned to resemble the experimental excess sorption data. The computed three-dimensional pore fluid density distributions show that the observed maximum of the excess sorption near the critical density originates from large density fluctuations pinned to the pore walls. At this maximum, the size of these fluctuations is comparable to the prevailing pore sizes.« less

Self-alignment of plasmonic gold nanorods in reconfigurable anisotropic fluids for tunable bulk metamaterial applications.

PubMed

Liu, Qingkun; Cui, Yanxia; Gardner, Dennis; Li, Xin; He, Sailing; Smalyukh, Ivan I

2010-04-14

We demonstrate the bulk self-alignment of dispersed gold nanorods imposed by the intrinsic cylindrical micelle self-assembly in nematic and hexagonal liquid crystalline phases of anisotropic fluids. External magnetic field and shearing allow for alignment and realignment of the liquid crystal matrix with the ensuing long-range orientational order of well-dispersed plasmonic nanorods. This results in a switchable polarization-sensitive plasmon resonance exhibiting stark differences from that of the same nanorods in isotropic fluids. The device-scale bulk nanoparticle alignment may enable optical metamaterial mass production and control of properties arising from combining the switchable nanoscale structure of anisotropic fluids with the surface plasmon resonance properties of the plasmonic nanorods.

Vein mineralizations - archives of paleo-fluid systems in the Thuringian basin (Germany)

NASA Astrophysics Data System (ADS)

Abratis, M.; Brey, M.; Fritsch, S.; Majzlan, J.; Viereck-Götte, L.

2012-04-01

We investigate vein mineralizations within and around the Thuringian basin (Germany) in order to characterize paleo-fluid systems that have been active in the basin. By investigating the composition, temperature, origin, age and evolution of paleo-fluids in the Thuringian basin as a model case, we aim for comprehensive understanding of the character of mineralized fluid systems in sedimentary basins in general and their evolution over geological time scales. Mineralizations along faults are archives for the composition of fluids which intruded the basin and circulated within it millions of years ago. These mineralizations give information on the physical and chemical characteristics of the related fluids as well as on their evolution with time during basin evolution. Mapping of mineralizations in space and time and comparison with the present-day fluid circulation system allows for recognition of the paleo-fluid dynamics and high temperature fluid influx pathways. The chemical characteristics of vein-related mineralizations are proxies for the paleo-fluid sources and their solution load. Methods implied comprise bulk rock analyses (petrography, XRD, XRF, ICP-MS), mineral analyses (EPMA, LA-ICP-MS), fluid inclusion measurements (microthermometry, Raman spectroscopy, ion chromatography) and isotope studies (O, H, C, S, Sr). Vein-related mineralizations within the Mesozoic sediments of the basin occur predominantly along WNW-ESE trending fault systems and comprise mainly carbonates and sulfates. Mineralizations within the basin-confining uplifted Variscan basement rocks and lowermost sedimentary units (Zechstein) show also (Fe-, Cu-, Zn-, As-, Sb-) sulfides, (Fe-, Mn-) oxides, fluorite and barite. The present study is part of INFLUINS, a BMBF-funded project bundle which is dedicated to comprehensive description and understanding of the fluid systems within the Thuringian basin in time and space.

Clumped isotopologue constraints on the origin of methane at seafloor hot springs

NASA Astrophysics Data System (ADS)

Wang, David T.; Reeves, Eoghan P.; McDermott, Jill M.; Seewald, Jeffrey S.; Ono, Shuhei

2018-02-01

Hot-spring fluids emanating from deep-sea vents hosted in unsedimented ultramafic and mafic rock commonly contain high concentrations of methane. Multiple hypotheses have been proposed for the origin(s) of this methane, ranging from synthesis via reduction of aqueous inorganic carbon (∑CO2) during active fluid circulation to leaching of methane-rich fluid inclusions from plutonic rocks of the oceanic crust. To further resolve the process(es) responsible for methane generation in these systems, we determined the relative abundances of several methane isotopologues (including 13CH3D, a "clumped" isotopologue containing two rare isotope substitutions) in hot-spring source fluids sampled from four geochemically-distinct hydrothermal vent fields (Rainbow, Von Damm, Lost City, and Lucky Strike). Apparent equilibrium temperatures retrieved from methane clumped isotopologue analyses average 310-42+53 °C, with no apparent relation to the wide range of fluid temperatures (96-370 °C) and chemical compositions (pH, [H2], [∑CO2], [CH4]) represented. Combined with very similar bulk stable isotope ratios (13C/12C and D/H) of methane across the suite of hydrothermal fluids, all available geochemical and isotopic data suggest a common mechanism of methane generation at depth that is disconnected from active fluid circulation. Attainment of equilibrium amongst methane isotopologues at temperatures of ca. 270-360 °C is compatible with the thermodynamically-favorable reduction of CO2 to CH4 at temperatures at or below ca. 400 °C under redox conditions characterizing intrusive rocks derived from sub-ridge melts. Collectively, the observations support a model where methane-rich aqueous fluids, known to be trapped in rocks of the oceanic lithosphere, are liberated from host rocks during hydrothermal circulation and perhaps represent the major source of methane venting with thermal waters at unsedimented hydrothermal fields. The results also provide further evidence that water-rock reactions occurring at temperatures lower than 200 °C do not contribute significantly to the quantities of methane venting at mid-ocean ridge hot springs.

Water Transport and the Evolution of CM Parent Bodies

NASA Technical Reports Server (NTRS)

Coker, Rob; Cohen, Barbara

2014-01-01

Meteorites have amino acids and hydrated minerals which constrain the peak temperature ranges they have experienced. CMs in particular have a narrow range (273-325K). Bulk fluid motion during hydration constrained to small scales (less than mm). Some asteroids are known to have hydrated minerals on their surfaces. It is presumed these two facts may be related. Problem: hydration only occurs (significantly) with liquid water; melting water only occurs early on in nebula (1-10 Myrs ANC); in nebula asteroid surface temperature very cold (approximately 150K). Can indigenous alteration produce CMs and/or surface hydration?

Experimental and Numerical Study of the Evaporation of Water at Low Pressures.

PubMed

Kazemi, Mohammad Amin; Nobes, David S; Elliott, Janet A W

2017-05-09

Although evaporation is considered to be a surface phenomenon, the rate of molecular transport across a liquid-vapor boundary is strongly dependent on the coupled fluid dynamics and heat transfer in the bulk fluids. Recent experimental thermocouple measurements of the temperature field near the interface of evaporating water into its vapor have begun to show the role of heat transfer in evaporation. However, the role of fluid dynamics has not been explored sufficiently. Here, we have developed a mathematical model to describe the coupling of the heat, mass, and momentum transfer in the fluids with the transport phenomena at the interface. The model was used to understand the experimentally obtained velocity field in the liquid and temperature profiles in the liquid and vapor, in evaporation from a concave meniscus for various vacuum pressures. By using the model, we have shown that an opposing buoyancy flow suppressed the thermocapillary flow in the liquid during evaporation at low pressures in our experiments. As such, in the absence of thermocapillary convection, the evaporation is controlled by heat transfer to the interface, and the predicted behavior of the system is independent of choosing between the existing theoretical expressions for evaporation flux. Furthermore, we investigated the temperature discontinuity at the interface and confirmed that the discontinuity strongly depends on the heat flux from the vapor side, which depends on the geometrical shape of the interface.

Gassmann Theory Applies to Nanoporous Media

NASA Astrophysics Data System (ADS)

Gor, Gennady Y.; Gurevich, Boris

2018-01-01

Recent progress in extraction of unconventional hydrocarbon resources has ignited the interest in the studies of nanoporous media. Since many thermodynamic and mechanical properties of nanoscale solids and fluids differ from the analogous bulk materials, it is not obvious whether wave propagation in nanoporous media can be described using the same framework as in macroporous media. Here we test the validity of Gassmann equation using two published sets of ultrasonic measurements for a model nanoporous medium, Vycor glass, saturated with two different fluids, argon, and n-hexane. Predictions of the Gassmann theory depend on the bulk and shear moduli of the dry samples, which are known from ultrasonic measurements and the bulk moduli of the solid and fluid constituents. The solid bulk modulus can be estimated from adsorption-induced deformation or from elastic effective medium theory. The fluid modulus can be calculated according to the Tait-Murnaghan equation at the solvation pressure in the pore. Substitution of these parameters into the Gassmann equation provides predictions consistent with measured data. Our findings set up a theoretical framework for investigation of fluid-saturated nanoporous media using ultrasonic elastic wave propagation.

A Deeper Understanding of Stability in the Solar Wind: Applying Nyquist's Instability Criterion to Wind Faraday Cup Data

NASA Astrophysics Data System (ADS)

Alterman, B. L.; Klein, K. G.; Verscharen, D.; Stevens, M. L.; Kasper, J. C.

2017-12-01

Long duration, in situ data sets enable large-scale statistical analysis of free-energy-driven instabilities in the solar wind. The plasma beta and temperature anisotropy plane provides a well-defined parameter space in which a single-fluid plasma's stability can be represented. Because this reduced parameter space can only represent instability thresholds due to the free energy of one ion species - typically the bulk protons - the true impact of instabilities on the solar wind is under estimated. Nyquist's instability criterion allows us to systematically account for other sources of free energy including beams, drifts, and additional temperature anisotropies. Utilizing over 20 years of Wind Faraday cup and magnetic field observations, we have resolved the bulk parameters for three ion populations: the bulk protons, beam protons, and alpha particles. Applying Nyquist's criterion, we calculate the number of linearly growing modes supported by each spectrum and provide a more nuanced consideration of solar wind stability. Using collisional age measurements, we predict the stability of the solar wind close to the sun. Accounting for the free-energy from the three most common ion populations in the solar wind, our approach provides a more complete characterization of solar wind stability.

Shock wave structure in rarefied polyatomic gases with large relaxation time for the dynamic pressure

NASA Astrophysics Data System (ADS)

Taniguchi, Shigeru; Arima, Takashi; Ruggeri, Tommaso; Sugiyama, Masaru

2018-05-01

The shock wave structure in rarefied polyatomic gases is analyzed based on extended thermodynamics (ET). In particular, the case with large relaxation time for the dynamic pressure, which corresponds to large bulk viscosity, is considered by adopting the simplest version of extended thermodynamics with only 6 independent fields (ET6); the mass density, the velocity, the temperature and the dynamic pressure. Recently, the validity of the theoretical predictions by ET was confirmed by the numerical analysis based on the kinetic theory in [S Kosuge and K Aoki: Phys. Rev. Fluids, Vol. 3, 023401 (2018)]. It was shown that numerical results using the polyatomic version of ellipsoidal statistical model agree with the theoretical predictions by ET for small or moderately large Mach numbers. In the present paper, first, we compare the theoretical predictions by ET6 with the ones by kinetic theory for large Mach number under the same assumptions, that is, the gas is polytropic and the bulk viscosity is proportional to the temperature. Second, the shock wave structure for large Mach number in a non-polytropic gas is analyzed with the particular interest in the effect of the temperature dependence of specific heat and the bulk viscosity on the shock wave structure. Through the analysis of the case of a rarefied carbon dioxide (CO2) gas, it is shown that these temperature dependences play important roles in the precise analysis of the structure for strong shock waves.

Off-shell hydrodynamics from holography

DOE PAGES

Crossley, Michael; Glorioso, Paolo; Liu, Hong; ...

2016-02-18

In this article, we outline a program for obtaining an action principle for dissipative fluid dynamics by considering the holographic Wilsonian renormalization group applied to systems with a gravity dual. As a first step, in this paper we restrict to systems with a non-dissipative horizon. By integrating out gapped degrees of freedom in the bulk gravitational system between an asymptotic boundary and a horizon, we are led to a formulation of hydrodynamics where the dynamical variables are not standard velocity and temperature fields, but the relative embedding of the boundary and horizon hypersurfaces. At zeroth order, this action reduces tomore » that proposed by Dubovsky et al. as an off-shell formulation of ideal fluid dynamics.« less

From dry to saturated thermal conductivity: mixing-model correction charts and new conversion equations for sedimentary rocks

NASA Astrophysics Data System (ADS)

Fuchs, Sven; Schütz, Felina; Förster, Andrea; Förster, Hans-Jürgen

2013-04-01

The thermal conductivity (TC) of a rock is, in collaboration with the temperature gradient, the basic parameter to determine the heat flow from the Earth interior. Moreover, it forms the input into models targeted on temperature prognoses for geothermal reservoirs at those depths not yet reached by boreholes. Thus, rock TC is paramount in geothermal exploration and site selection. Most commonly, TC of a rock is determined in the laboratory on samples that are either dry or water-saturated. Because sample saturation is time-consuming, it is desirable, especially if large numbers of samples need to be assessed, to develop an approach that quickly and reliably converts dry-measured bulk TC into the respective saturated value without applying the saturation procedure. Different petrophysical models can be deployed to calculate the matrix TC of a rock from the bulk TC and vice versa, if the effective porosity is known (e.g., from well logging data) and the TC of the saturation fluid (e.g., gas, oil, water) is considered. We have studied for a large suite of different sedimentary rocks the performance of two-component (rock matrix, porosity) models that are widely used in geothermics (arithmetic mean, geometric mean, harmonic mean, Hashin and Shtrikman mean, and effective medium theory mean). The data set consisted of 1147 TC data from three different sedimentary basins (North German Basin, Molasse Basin, Mesozoic platform sediments of the northern Sinai Microplate in Israel). Four lithotypes (sandstone, mudstone, limestone, dolomite) were studied exhibiting bulk TC in the range between 1.0 and 6.5 W/(mK). The quality of fit between measured (laboratory) and calculated bulk TC values was studied separately for the influence of lithotype, saturation fluid (water and isooctane), and rock anisotropy (parallel and perpendicular to bedding). The geometric mean model displays the best correspondence between calculated and measured bulk TC, however, the relation is not satisfying. To improve the fit of the models, correction equations are calculated based on the statistical data. In addition, the application of correction equations allows a significant improvement of the accuracy of bulk TC data calculated. However, the "corrected" geometric mean constitutes the only model universally applicable to different types of sedimentary rocks and, thus, is recommended for the calculation of bulk TC. Finally, the statistical analysis also resulted in lithotype-specific conversion equations, which permit a calculation of the water-saturated bulk TC from dry-measured TC and porosity (e.g., well-log-derived porosity). This approach has the advantage that the saturated bulk TC could be calculated readily without application of any mixing model. The expected errors with this approach are in the range between 5 and 10 % (Fuchs et al., 2013).

Oxygen isotope constraints on the alteration temperatures of CM chondrites

NASA Astrophysics Data System (ADS)

Verdier-Paoletti, Maximilien J.; Marrocchi, Yves; Avice, Guillaume; Roskosz, Mathieu; Gurenko, Andrey; Gounelle, Matthieu

2017-01-01

We report a systematic oxygen isotopic survey of Ca-carbonates in nine different CM chondrites characterized by different degrees of alteration, from the least altered known to date (Paris, 2.7-2.8) to the most altered (ALH 88045, CM1). Our data define a continuous trend that crosses the Terrestrial Fractionation Line (TFL), with a general relationship that is indistinguishable within errors from the trend defined by both matrix phyllosilicates and bulk O-isotopic compositions of CM chondrites. This bulk-matrix-carbonate (BMC) trend does not correspond to a mass-dependent fractionation (i.e., slope 0.52) as it would be expected during fluid circulation along a temperature gradient. It is instead a direct proxy of the degree of O-isotopic equilibration between 17,18O-rich fluids and 16O-rich anhydrous minerals. Our O-isotopic survey revealed that, for a given CM, no carbonate is in O-isotopic equilibrium with its respective surrounding matrix. This precludes direct calculation of the temperature of carbonate precipitation. However, the O-isotopic compositions of alteration water in different CMs (inferred from isotopic mass-balance calculation and direct measurements) define another trend (CMW for CM Water), parallel to BMC but with a different intercept. The distance between the BMC and CMW trends is directly related to the temperature of CM alteration and corresponds to average carbonates and serpentine formation temperatures of 110 °C and 75 °C, respectively. However, carbonate O-isotopic variations around the BMC trend indicate that they formed at various temperatures ranging between 50 and 300 °C, with 50% of the carbonates studied here showing precipitation temperature higher than 100 °C. The average Δ17O and the average carbonate precipitation temperature per chondrite are correlated, revealing that all CMs underwent similar maximum temperature peaks, but that altered CMs experienced protracted carbonate precipitation event(s) at lower temperatures than the least altered CMs. Our data suggest that the Δ17O value of Ca-carbonates could be a reliable proxy of the degree of alteration experienced by CM chondrites.

The campi flegrei (Italy) geothermal system: A fluid inclusion study of the mofete and San Vito fields

USGS Publications Warehouse

de, Vivo B.; Belkin, H.E.; Barbieri, M.; Chelini, W.; Lattanzi, P.; Lima, A.; Tolomeo, L.

1989-01-01

A fluid inclusion study of core from the Mofete 1, Mofete 2, Mofete 5, San Vito 1, and San Vito 3 geothermal wells (Campi Flegrei, Campania, Italy) indicates that the hydrothermal minerals were precipitated from aqueous fluids (??CO2) that were moderately saline (3-4 wt.% NaCl equiv.) to hypersaline (> 26 wt.% NaCl equiv.) and at least in part, boiling. Three types of primary fluid inclusions were found in authigenic K-feldspar, quartz, calcite, and epidote: (A) two-phase [liquid (L) + vapor (V)], liquid-rich inclusions with a range of salinity; (B) two-phase (L + V), vaporrich inclusions with low salinity; and (C) three-phase [L + V + crystals (NaCL)], liquid-rich inclusions with hypersalinity. Results of microthermometric and crushing studies are reported for twenty drill core samples taken from the lower portions of the five vertical wells. Data presented for selected core samples reveal a general decrease in porosity and increase in bulk density with increasing depth and temperature. Hydrothermal minerals commonly fill fractures and pore-spaces and define a zonation pattern, similar in all five wells studied, in response to increasing depth (pressure) and temperature. A greenschist facies assemblage, defined by albite + actinolite, gives way to an amphibolite facies, defined by plagioclase (andesine) + hornblende, in the San Vito 1 well at about 380??C. The fluid inclusion salinity values mimic the saline and hypersaline fluids found by drilling. Fluid inclusion V/L homogenization temperatures increase with depth and generally correspond to the extrapolated down-hole temperatures. However, fluid inclusion data for Mofete 5 and mineral assemblage data for San Vito 3, indicate fossil, higher-temperature regimes. A limited 87Sr/86Sr study of leachate (carbonate) and the leached cores shows that for most samples (except San Vito 3) the carbonate deposition has been from slightly 87Sr-enriched fluids and that Sr isotopic exchange has been incomplete. However, San Vito 3 cores show an approach to fluid/rock Sr equilibrium with a fluid similar to modern ocean water in 87Sr/86Sr ratio. The Campi Flegrei volcanic system has evolved undersaturated products, mostly trachyte, and defines a large (??? 12 km) caldera. The hydrothermal system developed in this location can be used as an analog for fossil systems in similar trachytic environments. The potential for ore mineralization is expressed by the recognition, from fluid inclusion and drilling data, of ore-forming environments such as boiling and brine stratification. ?? 1989.

Stimuli Responsive/Rheoreversible Hydraulic Fracturing Fluids for Enhanced Geothermal Energy Production (Part II)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bonneville, Alain; Jung, Hun Bok; Shao, Hongbo

We have used an environmentally friendly and recyclable hydraulic fracturing fluid - diluted aqueous solutions of polyallylamine or PAA – for reservoir stimulation in Enhanced Geothermal System (EGS). This fluid undergoes a controlled and large volume expansion with a simultaneous increase in viscosity triggered by CO2 at EGS temperatures. We are presenting here the results of laboratory-scale hydraulic fracturing experiment using the fluid on small cylindrical rock cores (1.59 cm in diameter and 5.08 cm in length) from the Coso geothermal field in California. Rock samples consisted of Mesozoic diorite metamorphosed to greenschist facies. The experiments were conducted on 5more » samples for realistic ranges of pressures (up to 275 bar) and temperatures (up to 210 °C) for both the rock samples and the injected fluid. After fracturing, cores were subjected to a CO2 leakage test, injection of KI solution, and X-ray microtomography (XMT) scanning to examine the formation and distribution of fractures. The design and conduct of these experiments will be presented and discussed in details. Based on the obtained XMT images, Computational Fluid Dynamics (CFD) simulations were then performed to visualize hydraulic fractures and compute the bulk permeability. OpenFOAM (OpenCFD Ltd., Reading, UK), was used to solve the steady state simulation. The flow predictions, based upon the laminar, 3-D, incompressible Navier-Stokes equations for fluid mass and momentum, show the remarkable stimulation of the permeability in the core samples and demonstrate the efficiency of such a CO2 triggered fluid in EGS.« less

Estimation of Dry Fracture Weakness, Porosity, and Fluid Modulus Using Observable Seismic Reflection Data in a Gas-Bearing Reservoir

NASA Astrophysics Data System (ADS)

Chen, Huaizhen; Zhang, Guangzhi

2017-05-01

Fracture detection and fluid identification are important tasks for a fractured reservoir characterization. Our goal is to demonstrate a direct approach to utilize azimuthal seismic data to estimate fluid bulk modulus, porosity, and dry fracture weaknesses, which decreases the uncertainty of fluid identification. Combining Gassmann's (Vier. der Natur. Gesellschaft Zürich 96:1-23, 1951) equations and linear-slip model, we first establish new simplified expressions of stiffness parameters for a gas-bearing saturated fractured rock with low porosity and small fracture density, and then we derive a novel PP-wave reflection coefficient in terms of dry background rock properties (P-wave and S-wave moduli, and density), fracture (dry fracture weaknesses), porosity, and fluid (fluid bulk modulus). A Bayesian Markov chain Monte Carlo nonlinear inversion method is proposed to estimate fluid bulk modulus, porosity, and fracture weaknesses directly from azimuthal seismic data. The inversion method yields reasonable estimates in the case of synthetic data containing a moderate noise and stable results on real data.

FLUIDS, LUBRICANTS, FUELS AND RELATED MATERIALS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klaus, E.E.; Fenske, M.R.; Tewksbury, E.J.

1961-01-01

Work was carried out on a continuing program to characterize the capabilities of hydraulic fluids, lubricants, and functional fluids for aeronautic and astronautic applications under extreme environmental conditions. The effects of solvent type and solvent to oil ratio on the deep dewaxing process are shown. The yield and viscosity-temperature properties of the deep dewaxed oil are related to the type and degree of refining of the mineral oil fraction. The preparation of large volumes of super-refined mineral oil formulations for ""mock-up'' testing is reponted. Extensive technical liaison on processing, properties, and application is discussed. Physical and chemical stability of basemore » stocks, additives, and finished hydraulic fluid and lubricant formulations after 5 to 17 years in storage is described. A sample of hydraulic fluid taken from the "Lady Be Good" B-25 Bomber after 16 years in the North African desert is discussed. The design, construction, and preliminary testing of a versatile capillary pressure viscometer is reported. The use of this viscometer to measure the effect of gas solubility on viscosity and the analysis of flow profile in a capillary viscometer are discussed. The use of the pressure unit with a modified Lipkin pycnometer for the measure of bulk modulus is suggested. The thermal stability of esters is contrasted and compared as a function of chemical structure. Quantitative evaluations of the gas produced and the liquid phase are used to illustrate the effect of metal catalysts. The effects of fluid type, viscosity, vapor pressure, oxidation mechanism, oxidation inhibitor, and gaseous environment on evaporation are presented. The use of evaporation tests in studying the mechanism of oxidation is suggested. The relative lubricity properties of a series of high-temperature-bearing materials are reported. The relative effects of fluid volatility on lubricity are discussed. The similarities between high-temperature and the lowtemperatare lubricity properties of the residual fluids after high-temperature oxidation and thermal tests are pointed out. The wear properties of mineral oils and esters with and without lubricity additives are compared and contrasted with silicons and silicate fluids at 167 to 700 deg F. A simple, versatile, quantitative oxidation test is described for use with a variety of high-temperature oxidation tests. (auth)« less

Heat transfer from high-temperature surfaces to fluids II : correlation of heat-transfer and friction data for air flowing in inconel tube with rounded entrance

NASA Technical Reports Server (NTRS)

Lowdermilk, Warren H; Grele, Milton D

1949-01-01

A heat transfer investigation, which was an extension of a previously reported NACA investigation, was conducted with air flowing through an electrically heated inconel tube with a rounded entrance,an inside diameter of 0.402 inch, and a length of 24 inches over a range of conditions, which included Reynolds numbers up to 500,000, average surface temperatures up to 2050 degrees R, and heat-flux densities up to 150,000 Btu per hour per square foot. Conventional methods of correlating heat-transfer data wherein properties of the air were evaluated at the average bulk, film, and surface temperatures resulted in reductions of Nusselt number of about 38, 46, and 53 percent, respectively, for an increase in surface temperature from 605 degrees to 2050 degrees R at constant Reynolds number. A modified correlation method in which the properties of air were based on the surface temperature and the Reynolds number was modified by substituting the product of the density at the inside tube wall and the bulk velocity for the conventional mass flow per unit cross-sectional area, resulted in a satisfactory correlation of the data for the extended ranges of conditions investigated.

Numerical analysis of seawater circulation in carbonate platforms: I. Geothermal convection

USGS Publications Warehouse

Sanford, W.E.; Whitaker, F.F.; Smart, P.L.; Jones, G.

1998-01-01

Differences in fluid density between cold ocean water and warm ground water can drive the circulation of seawater through carbonate platforms. The circulating water can be the major source of dissolved constituents for diagenetic reactions such as dolomitization. This study was undertaken to investigate the conditions under which such circulation can occur and to determine which factors control both the flux and the patterns of fluid circulation and temperature distribution, given the expected ranges of those factors in nature. Results indicate that the magnitude and distribution of permeability within a carbonate platform are the most important parameters. Depending on the values of horizontal and vertical permeability, heat transport within a platform can occur by one of three mechanisms: conduction, forced convection, or free convection. Depth-dependent relations for porosity and permeability in carbonate platforms suggest circulation may decrease rapidly with depth. The fluid properties of density and viscosity are controlled primarily by their dependency on temperature. The bulk thermal conductivity of the rocks within the platform affects the conductive regime to some extent, especially if evaporite minerals are present within the section. Platform geometry has only a second-order effect on circulation. The relative position of sealevel can create surface conditions that range from exposed (with a fresh-water lens present) to shallow water (with hypersaline conditions created by evaporation in constricted flow conditions) to submerged or drowned (with free surface water circulation), but these boundary conditions and associated ocean temperature profiles have only a second-order effect on fluid circulation. Deep, convective circulation can be caused by horizon tal temperature gradients and can occur even at depths below the ocean bottom. Temperature data from deep holes in the Florida and Bahama platforms suggest that geothermal circulation is actively occurring today to depths as great as several kilometers.

Thermal evolution of plutons: a parameterized approach.

PubMed

Spera, F

1980-01-18

A conservation-of-energy equation has been derived for the spatially averaged magma temperature in a spherical pluton undergoing simultaneous crystallization and both internal (magma) and external (hydrothermal fluid) thermal convection. The model accounts for the dependence of magma viscosity on crystallinity, temperature, and bulk composition; it includes latent heat effects and the effects of different initial water concentrations in the melt and quantitatively considers the role that large volumes of circulatory hydrothermal fluids play in dissipating heat. The nonlinear ordinary differential equation describing these processes has been solved for a variety of magma compositions, initial termperatures, initial crystallinities, volume ratios of hydrothermal fluid to magma, and pluton sizes. These calculations are graphically summarized in plots of the average magma temperature versus time after emplacement. Solidification times, defined as the time necessary for magma to cool from the initial emplacement temperature to the solidus temperature vary as R(1,3), where R is the pluton radius. The solidification time of a pluton with a radius of 1 kilometer is 5 x 10(4) years; for an otherwise identical pluton with a radius of 10 kilometers, the solidification time is approximately 10(6) years. The water content has a marked effect on the solidification time. A granodiorite pluton with a radius of 5 kilometers and either 0.5 or 4 percent (by weight) water cools in 3.3 x 10(5) or 5 x 10(4) years, respectively. Convection solidification times are usually but not always less than conduction cooling times.

On the early and developed stages of surface condensation: competition mechanism between interfacial and condensate bulk thermal resistances.

PubMed

Sun, Jie; Wang, Hua Sheng

2016-10-10

We use molecular dynamics simulation to investigate the early and developed stages of surface condensation. We find that the liquid-vapor and solid-liquid interfacial thermal resistances depend on the properties of solid and fluid, which are time-independent, while the condensate bulk thermal resistance depends on the condensate thickness, which is time-dependent. There exists intrinsic competition between the interfacial and condensate bulk thermal resistances in timeline and the resultant total thermal resistance determines the condensation intensity for a given vapor-solid temperature difference. We reveal the competition mechanism that the interfacial thermal resistance dominates at the onset of condensation and holds afterwards while the condensate bulk thermal resistance gradually takes over with condensate thickness growing. The weaker the solid-liquid bonding, the later the takeover occurs. This competition mechanism suggests that only when the condensate bulk thermal resistance is reduced after it takes over the domination can the condensation be effectively intensified. We propose a unified theoretical model for the thermal resistance analysis by making dropwise condensation equivalent to filmwise condensation. We further find that near a critical point (contact angle being ca. 153°) the bulk thermal resistance has the least opportunity to take over the domination while away from it the probability increases.

On the early and developed stages of surface condensation: competition mechanism between interfacial and condensate bulk thermal resistances

PubMed Central

Sun, Jie; Wang, Hua Sheng

2016-01-01

We use molecular dynamics simulation to investigate the early and developed stages of surface condensation. We find that the liquid-vapor and solid-liquid interfacial thermal resistances depend on the properties of solid and fluid, which are time-independent, while the condensate bulk thermal resistance depends on the condensate thickness, which is time-dependent. There exists intrinsic competition between the interfacial and condensate bulk thermal resistances in timeline and the resultant total thermal resistance determines the condensation intensity for a given vapor-solid temperature difference. We reveal the competition mechanism that the interfacial thermal resistance dominates at the onset of condensation and holds afterwards while the condensate bulk thermal resistance gradually takes over with condensate thickness growing. The weaker the solid-liquid bonding, the later the takeover occurs. This competition mechanism suggests that only when the condensate bulk thermal resistance is reduced after it takes over the domination can the condensation be effectively intensified. We propose a unified theoretical model for the thermal resistance analysis by making dropwise condensation equivalent to filmwise condensation. We further find that near a critical point (contact angle being ca. 153°) the bulk thermal resistance has the least opportunity to take over the domination while away from it the probability increases. PMID:27721397

Boundary versus bulk behavior of time-dependent correlation functions in one-dimensional quantum systems

NASA Astrophysics Data System (ADS)

Eliëns, I. S.; Ramos, F. B.; Xavier, J. C.; Pereira, R. G.

2016-05-01

We study the influence of reflective boundaries on time-dependent responses of one-dimensional quantum fluids at zero temperature beyond the low-energy approximation. Our analysis is based on an extension of effective mobile impurity models for nonlinear Luttinger liquids to the case of open boundary conditions. For integrable models, we show that boundary autocorrelations oscillate as a function of time with the same frequency as the corresponding bulk autocorrelations. This frequency can be identified as the band edge of elementary excitations. The amplitude of the oscillations decays as a power law with distinct exponents at the boundary and in the bulk, but boundary and bulk exponents are determined by the same coupling constant in the mobile impurity model. For nonintegrable models, we argue that the power-law decay of the oscillations is generic for autocorrelations in the bulk, but turns into an exponential decay at the boundary. Moreover, there is in general a nonuniversal shift of the boundary frequency in comparison with the band edge of bulk excitations. The predictions of our effective field theory are compared with numerical results obtained by time-dependent density matrix renormalization group (tDMRG) for both integrable and nonintegrable critical spin-S chains with S =1 /2 , 1, and 3 /2 .

Subcooled Pool Boiling Heat Transfer Mechanisms in Microgravity: Terrier-improved Orion Sounding Rocket Experiment

NASA Technical Reports Server (NTRS)

Kim, Jungho; Benton, John; Kucner, Robert

2000-01-01

A microscale heater array was used to study boiling in earth gravity and microgravity. The heater array consisted of 96 serpentine heaters on a quartz substrate. Each heater was 0.27 square millimeters. Electronic feedback loops kept each heater's temperature at a specified value. The University of Maryland constructed an experiment for the Terrier-Improved Orion sounding rocket that was delivered to NASA Wallops and flown. About 200 s of high quality microgravity and heat transfer data were obtained. The VCR malfunctioned, and no video was acquired. Subsequently, the test package was redesigned to fly on the KC-135 to obtain both data and video. The pressure was held at atmospheric pressure and the bulk temperature was about 20 C. The wall temperature was varied from 85 to 65 C. Results show that gravity has little effect on boiling heat transfer at wall superheats below 25 C, despite vast differences in bubble behavior between gravity levels. In microgravity, a large primary bubble was surrounded by smaller bubbles, which eventually merged with the primary bubble. This bubble was formed by smaller bubbles coalescing, but had a constant size for a given superheat, indicating a balance between evaporation at the base and condensation on the cap. Most of the heaters under the bubble indicated low heat transfer, suggesting dryout at those heaters. High heat transfer occurred at the contact line surrounding the primary bubble. Marangoni convection formed a "jet" of fluid into the bulk fluid that forced the bubble onto the heater.

Trace elements in magnetite as petrogenetic indicators

NASA Astrophysics Data System (ADS)

Dare, Sarah A. S.; Barnes, Sarah-Jane; Beaudoin, Georges; Méric, Julien; Boutroy, Emilie; Potvin-Doucet, Christophe

2014-10-01

We have characterized the distribution of 25 trace elements in magnetite (Mg, Al, Si, P, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Ge, Y, Zr, Nb, Mo, Sn, Hf, Ta, W, and Pb), using laser ablation ICP-MS and electron microprobe, from a variety of magmatic and hydrothermal ore-forming environments and compared them with data from the literature. We propose a new multielement diagram, normalized to bulk continental crust, designed to emphasize the partitioning behavior of trace elements between magnetite, the melt/fluid, and co-crystallizing phases. The normalized pattern of magnetite reflects the composition of the melt/fluid, which in both magmatic and hydrothermal systems varies with temperature. Thus, it is possible to distinguish magnetite formed at different degrees of crystal fractionation in both silicate and sulfide melts. The crystallization of ilmenite or sulfide before magnetite is recorded as a marked depletion in Ti or Cu, respectively. The chemical signature of hydrothermal magnetite is distinct being depleted in elements that are relatively immobile during alteration and commonly enriched in elements that are highly incompatible into magnetite (e.g., Si and Ca). Magnetite formed from low-temperature fluids has the lowest overall abundance of trace elements due to their lower solubility. Chemical zonation of magnetite is rare but occurs in some hydrothermal deposits where laser mapping reveals oscillatory zoning, which records the changing conditions and composition of the fluid during magnetite growth. This new way of plotting all 25 trace elements on 1 diagram, normalized to bulk continental crust and elements in order of compatibility into magnetite, provides a tool to help understand the processes that control partitioning of a full suit of trace elements in magnetite and aid discrimination of magnetite formed in different environments. It has applications in both petrogenetic and provenance studies, such as in the exploration of ore deposits and in sedimentology.

L4 Milestone Report for MixEOS 2016 experiments and simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Loomis, Eric Nicholas; Bradley, Paul Andrew; Merritt, Elizabeth Catherine

2016-08-01

Accurate simulations of fluid and plasma flows require accurate thermodynamic properties of the fluids or plasmas. This thermodynamic information is represented by the equations of state of the materials. For pure materials, the equations of state may be represented by analytical models for idealized circumstances, or by tabular means, such as the Sesame tables. However, when a computational cell has a mixture of two or more fluids, the equations of state are not well understood, particularly under the circumstances of high energy densities. This is a particularly difficult issue for Eulerian codes, wherein mixed cells arise simply due to themore » advection process. LANL Eulerian codes typically assume an “Amagat’s Law” (or Law of Partial Volumes) for the mixture in which the pressures and temperatures of fluids are at an equilibrium that is consistent with the fluids being segregated within the cell. However, for purposes of computing other EOS properties, e.g., bulk modulus, or sound speed, the fluids are considered to be fully “mixed”. LANL has also been investigating implementing instead “Dalton’s Law” in which the total pressure is considered to be the sum of the partial pressures within the cell. For ideal gases, these two laws give the same result. Other possibilities are nonpressure- temperature-equilibrated approaches in which the two fluids are not assumed to “mix” at all, and the EOS properties of the cell are computed from, say, volume-weighted averages of the individual fluid properties. The assumption of the EOS properties within a mixed cell can have a pronounced effect on the behavior of the cell, resulting in, for example, different shock speeds, pressures, temperatures and densities within the cell. There is no apparent consensus as to which approach is best under HED conditions, though we note that under typical atmospheric and near atmospheric conditions the differences may be slight.« less

Continuum kinetic and multi-fluid simulations of classical sheaths

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cagas, P.; Hakim, A.; Juno, J.

The kinetic study of plasma sheaths is critical, among other things, to understand the deposition of heat on walls, the effect of sputtering, and contamination of the plasma with detrimental impurities. The plasma sheath also provides a boundary condition and can often have a significant global impact on the bulk plasma. In this paper, kinetic studies of classical sheaths are performed with the continuum kinetic code, Gkeyll, which directly solves the Vlasov-Maxwell equations. The code uses a novel version of the finite-element discontinuous Galerkin scheme that conserves energy in the continuous-time limit. The fields are computed using Maxwell equations. Ionizationmore » and scattering collisions are included; however, surface effects are neglected. The aim of this work is to introduce the continuum kinetic method and compare its results with those obtained from an already established finite-volume multi-fluid model also implemented in Gkeyll. Novel boundary conditions on the fluids allow the sheath to form without specifying wall fluxes, so the fluids and fields adjust self-consistently at the wall. Our work demonstrates that the kinetic and fluid results are in agreement for the momentum flux, showing that in certain regimes, a multifluid model can be a useful approximation for simulating the plasma boundary. There are differences in the electrostatic potential between the fluid and kinetic results. Further, the direct solutions of the distribution function presented here highlight the non-Maxwellian distribution of electrons in the sheath, emphasizing the need for a kinetic model. The densities, velocities, and the potential show a good agreement between the kinetic and fluid results. But, kinetic physics is highlighted through higher moments such as parallel and perpendicular temperatures which provide significant differences from the fluid results in which the temperature is assumed to be isotropic. Besides decompression cooling, the heat flux is shown to play a role in the temperature differences that are observed, especially inside the collisionless sheath. Published by AIP Publishing.« less

Continuum kinetic and multi-fluid simulations of classical sheaths

DOE PAGES

Cagas, P.; Hakim, A.; Juno, J.; ...

2017-02-21

The kinetic study of plasma sheaths is critical, among other things, to understand the deposition of heat on walls, the effect of sputtering, and contamination of the plasma with detrimental impurities. The plasma sheath also provides a boundary condition and can often have a significant global impact on the bulk plasma. In this paper, kinetic studies of classical sheaths are performed with the continuum kinetic code, Gkeyll, which directly solves the Vlasov-Maxwell equations. The code uses a novel version of the finite-element discontinuous Galerkin scheme that conserves energy in the continuous-time limit. The fields are computed using Maxwell equations. Ionizationmore » and scattering collisions are included; however, surface effects are neglected. The aim of this work is to introduce the continuum kinetic method and compare its results with those obtained from an already established finite-volume multi-fluid model also implemented in Gkeyll. Novel boundary conditions on the fluids allow the sheath to form without specifying wall fluxes, so the fluids and fields adjust self-consistently at the wall. Our work demonstrates that the kinetic and fluid results are in agreement for the momentum flux, showing that in certain regimes, a multifluid model can be a useful approximation for simulating the plasma boundary. There are differences in the electrostatic potential between the fluid and kinetic results. Further, the direct solutions of the distribution function presented here highlight the non-Maxwellian distribution of electrons in the sheath, emphasizing the need for a kinetic model. The densities, velocities, and the potential show a good agreement between the kinetic and fluid results. But, kinetic physics is highlighted through higher moments such as parallel and perpendicular temperatures which provide significant differences from the fluid results in which the temperature is assumed to be isotropic. Besides decompression cooling, the heat flux is shown to play a role in the temperature differences that are observed, especially inside the collisionless sheath. Published by AIP Publishing.« less

Characterization of Magma-Driven Hydrothermal Systems at Oceanic Spreading Centers

NASA Astrophysics Data System (ADS)

Farough, A.; Lowell, R. P.; Corrigan, R.

2012-12-01

Fluid circulation in high-temperature hydrothermal systems involves complex water-rock chemical reactions and phase separation. Numerical modeling of reactive transport in multi-component, multiphase systems is required to obtain a full understanding of the characteristics and evolution of hydrothermal vent systems. We use a single-pass parameterized model of high-temperature hydrothermal circulation at oceanic spreading centers constrained by observational parameters such as vent temperature, heat output, and vent field area, together with surface area and depth of the sub-axial magma chamber, to deduce fundamental hydrothermal parameters such as mass flow rate, bulk permeability, conductive boundary layer thickness at the base of the system, magma replenishment rate, and residence time in the discharge zone. All of these key subsurface characteristics are known for fewer than 10 sites out of 300 known hydrothermal systems. The principal limitations of this approach stem from the uncertainty in heat output and vent field area. For systems where data are available on partitioning of heat and chemical output between focused and diffuse flow, we determined the fraction of high-temperature vent fluid incorporated into diffuse flow using a two-limb single pass model. For EPR 9°50` N and ASHES, the diffuse flow temperatures calculated assuming conservative mixing are nearly equal to the observed temperatures indicating that approximately 80%-90% of the hydrothermal heat output occurs as high-temperature flow derived from magmatic heat even though most of the heat output appears as low-temperature diffuse discharge. For the Main Endeavour Field and Lucky Strike, diffuse flow fluids show significant conductive cooling and heating respectively. Finally, we calculate the transport of various geochemical constituents in focused and diffuse flow at the vent field scale and compare the results with estimates of geochemical transports from the Rainbow hydrothermal field where diffuse flow is absent.

HPHT reservoir evolution: a case study from Jade and Judy fields, Central Graben, UK North Sea

NASA Astrophysics Data System (ADS)

di Primio, Rolando; Neumann, Volkmar

2008-09-01

3D basin modelling of a study area in Quadrant 30, UK North Sea was performed in order to elucidate the burial, thermal, pressure and hydrocarbon generation, migration and accumulation history in the Jurassic and Triassic high pressure high temperature sequences. Calibration data, including reservoir temperatures, pressures, petroleum compositional data, vitrinite reflectance profiles and published fluid inclusion data were used to constrain model predictions. The comparison of different pressure generating processes indicated that only when gas generation is taken into account as a pressure generating mechanism, both the predicted present day as well as palaeo-pressure evolution matches the available calibration data. Compositional modelling of hydrocarbon generation, migration and accumulation also reproduced present and palaeo bulk fluid properties such as the reservoir fluid gas to oil ratios. The reconstruction of the filling histories of both reservoirs indicates that both were first charged around 100 Ma ago and contained initially a two-phase system in which gas dominated volumetrically. Upon burial reservoir fluid composition evolved to higher GORs and became undersaturated as a function of increasing pore pressure up to the present day situation. Our results indicate that gas compositions must be taken into account when calculating the volumetric effect of gas generation on overpressure.

Structure, alteration, and geochemistry of the Charlotte quartz vein stockwork, Mt Charlotte gold mine, Kalgoorlie, Australia: time constraints, down-plunge zonation, and fluid source

NASA Astrophysics Data System (ADS)

Mueller, Andreas G.

2015-02-01

The Kalgoorlie district in the Archean Yilgarn Craton, Western Australia, comprises two world-class gold deposits: Mt Charlotte (144 t Au produced to 2013) in the northwest and the Golden Mile (1,670 t Au) in the southeast. Both occur in a folded greenschist-facies gabbro sill adjacent to the Golden Mile Fault (D2) in propylitic alteration associated with porphyry dikes. At Mt Charlotte, a shear array of fault-fill veins within the Golden Mile Fault indicates sinistral strike-slip during Golden Mile-type pyrite-telluride mineralization. The pipe-shaped Charlotte quartz vein stockwork, mined in bulk more than 1 km down plunge, is separated in time by barren D3 thrusts from Golden Mile mineralization and alteration, and occurs between two dextral strike-slip faults (D4). Movement on these faults generated an organized network of extension and shear fractures opened during the subsequent infiltration of high-pressure H2S-rich fluid at 2,655 ± 13 Ma (U-Pb xenotime). Gold was deposited during wall rock sulphidation in overlapping vein selvages zoned from deep albite-pyrrhotite (3 g/t Au) to upper muscovite-pyrite assemblages (5 g/t Au bulk grade). Chlorite and fluid inclusion thermometry indicate that this kilometre-scale zonation is due to fluid cooling from 410-440 °C at the base to 350-360 °C at the top of the orebody, while the greenstone terrane remained at 250 °C ambient temperature and at 300 MPa lithostatic pressure. The opened fractures filled with barren quartz and scheelite during the retrograde stage (300 °C) of the hydrothermal event. During fracture sealing, fluid flux was periodically restricted at the lower D3 thrust. Cycles of high and low up-flow, represented by juvenile H2O-CO2 and evolved H2O-CO2-CH4 fluid, respectively, are recorded by the REE and Sr isotope compositions of scheelite oscillatory zones. The temperature gradient measured in the vein stockwork points to a hot (>600 °C) fluid source 2-4 km below the mine workings, and several kilometres above the base of the greenstone belt. Mass balance calculations involving bulk ore indicate enrichment of both felsic (K, Rb, Cs, Li, Ba, W) and mafic elements (Ca, Sr, Mg, Ni, V, Cr, Te), a source signature compatible with the local high-Mg porphyry suite but not with the meta-gabbro host rock. The initial 87Sr/86Sr ratios of the vein scheelites (0.7014-0.7016) are higher than the mantle ratio of the meta-gabbro (0.7009-0.7011) and overlap those of high-Mg monzodiorite intrusions (0.7016-0.7018) emplaced along the Golden Mile Fault at 2,662 ± 6 Ma to 2,658 ± 3 Ma.

Melting/freezing behavior of a fluid confined in porous glasses and MCM-41: Dielectric spectroscopy and molecular simulation

NASA Astrophysics Data System (ADS)

Sliwinska-Bartkowiak, Malgorzata; Dudziak, Grazyna; Sikorski, Roman; Gras, Roman; Radhakrishnan, Ravi; Gubbins, Keith E.

2001-01-01

We report both experimental measurements and molecular simulations of the melting and freezing behavior of fluids in nanoporous media. The experimental studies are for nitrobenzene in the silica-based pores of controlled pore glass, Vycor, and MCM-41. Dielectric relaxation spectroscopy is used to determine melting points and the orientational relaxation times of the nitrobenzene molecules in the bulk and the confined phase. Monte Carlo simulations, together with a bond orientational order parameter method, are used to determine the melting point and fluid structure inside cylindrical pores modeled on silica. Qualitative comparison between experiment and simulation are made for the shift in the freezing temperatures and the structure of confined phases. From both the experiments and the simulations, it is found that the confined fluid freezes into a single crystalline structure for average pore diameters greater than 20σ, where σ is the diameter of the fluid molecule. For average pore sizes between 20σ and 15σ, part of the confined fluid freezes into a frustrated crystal structure with the rest forming an amorphous region. For pore sizes smaller than 15σ, even the partial crystallization did not occur. Our measurements and calculations show clear evidence of a novel intermediate "contact layer" phase lying between liquid and crystal; the contact layer is the confined molecular layer adjacent to the pore wall and experiences a deeper fluid-wall potential energy compared to the inner layers. We also find evidence of a liquid to "hexatic" transition in the quasi-two-dimensional contact layer at high temperatures.

Combined effects of molecular geometry and nanoconfinement on liquid flows through carbon nanotubes

NASA Astrophysics Data System (ADS)

Suga, Kazuhiko; Mori, Yuki; Moritani, Rintaro; Kaneda, Masayuki

2018-05-01

Molecular dynamics simulations are carried out to investigate the geometry effects of diatomic molecules on liquid flows in carbon nanotubes (CNTs). Oxygen molecules are considered as the fluid inside armchair (n ,n ) (n =6 -20 ) CNTs. The simulated fluid temperature and bulk pressure for the liquid state are T =133 K and ρb=1346 kg/m 3 , respectively. In the agglomerated molecular cluster, nanoconfinement-induced structural changes are observed. As the CNT diameter decreases, it is confirmed that the flow rate significantly increases with irregular trends (discontinuity points in the profiles). From the discussion of the structure of the agglomerated fluid molecules, it is found that those trends are not simply caused by the structural changes. The main factor to induce the irregularity is confirmed to be the interlayer molecular movement affected by the combination of the molecular geometry and the arrangement of the multilayered structure.

Bulk viscosity of water in acoustic modal analysis and experiment

NASA Astrophysics Data System (ADS)

Kůrečka, Jan; Habán, Vladimír; Himr, Daniel

2018-06-01

Bulk viscosity is an important factor in the damping properties of fluid systems and exhibits frequency dependent behaviour. A comparison between modal analysis in ANSYS Acoustics, custom code and experimental data is presented in this paper. The measured system consists of closed ended water-filled steel pipes of different lengths. The influence of a pipe wall, flanges on both ends and longitudinal waves in the structural part were included in measurement evaluation. Therefore, the obtained values of sound speed and bulk viscosity are parameters of the fluid. A numerical simulation was carried out only using fluid volume in a range of bulk viscosity. Damping characteristics in this range were compared to measured values. The results show a significant influence of sound speed and subsequently, the use of sound speed value regressed from experimental data yields a better fit between the measurement and the computation.

Various continuum approaches for studying shock wave structure in carbon dioxide

NASA Astrophysics Data System (ADS)

Alekseev, I. V.; Kosareva, A. A.; Kustova, E. V.; Nagnibeda, E. A.

2018-05-01

Shock wave structure in carbon dioxide is studied using different continuum models within the framework of one-temperature thermal equilibrium flow description. Navier-Stokes and Euler equations as well as commonly used Rankine-Hugoniot equations with different specific heat ratios are used to find the gas-dynamic parameters behind the shock wave. The accuracy of the Rankine-Hugoniot relations in polyatomic gases is assessed, and it is shown that they give a considerable error in the predicted values of fluid-dynamic variables. The effect of bulk viscosity on the shock wave structure in CO2 is evaluated. Taking into account bulk viscosity yields a significant increase in the shock wave width; for the complete model, the shock wave thickness varies non-monotonically with the Mach number.

A new technique for surface and shallow subsurface paleobarometry using fluid inclusions: An example from the Upper Ordovician Viola Formation, Kansas, USA

USGS Publications Warehouse

Newell, K.D.; Goldstein, R.H.

1999-01-01

This research illustrates a new approach for paleobarometry employing heterogeneously entrapped fluid inclusions to determine timing and depth of diagenesis. Heterogeneously entrapped fluid inclusions (gas + water) in vug-filling quartz from the Upper Ordovician Viola Formation in the Midcontinent of the United States were analyzed for their internal pressure with a fluid-inclusion crushing stage. The free gas in fluid inclusions was entrapped at near-surface temperature, as indicated by the presence of all-liquid fluid inclusions and fluid inclusions with low homogenization temperatures ( <40??C). Crushing the crystal and measuring the change in bubble size determines the pressure of entrapment directly. Heterogeneous trapping is indicated by widely varying L:V ratios, from all-liquid to vapor-rich. Gas bubbles in most fluid inclusions analyzed expanded upon release to atmospheric pressure, but some collapsed. A mode of 1.5 to 2.0 atm internal pressure was indicated by the crushing runs, but pressures up to 42.9 atm were recorded. Quartz precipitation and associated fluid-inclusion entrapment therefore occurred over a wide depth-range, but principally at depths of approximately 10 m. Crushing runs done in kerosene confirmed the presence of hydrocarbon gases in most of these inclusions, and bulk analyses of gases in the quartz by quadrupole mass spectrometer revealed methane, ethane, and atmospheric gases. The hydrocarbon gases may have originated in deeper thermogenically mature sedimentary strata, and then leaked to the near-surface where they were entrapped in the precipitating quartz cement. Freezing data indicate an event of quartz precipitation from fluids of marine-fresh water intermediate salinity and other events of precipitation from more saline fluids. Considering the determined pressures, the precipitating fluids probably originated at surfaces of subaerial exposure (unconformities) and surfaces of evaporite precipitation in the overlying Silurian strata. Thus, saline inclusions most likely originated from sinking of saline surface waters during Silurian time. Lower-salinity fluids record fluxes of meteoric water during development of unconformities in the Silurian. This type of paleobarometric study may have application in many other sedimentary systems, provided low-temperature and heterogeneous entrapment of an immiscible gas phase can be demonstrated for the fluid-inclusion assemblages studied.

Two fluid anisotropic dark energy models in a scale invariant theory

NASA Astrophysics Data System (ADS)

Tripathy, S. K.; Mishra, B.; Sahoo, P. K.

2017-09-01

Some anisotropic Bianchi V dark energy models are investigated in a scale invariant theory of gravity. We consider two non-interacting fluids such as dark energy and a bulk viscous fluid. Dark energy pressure is considered to be anisotropic in different spatial directions. A dynamically evolving pressure anisotropy is obtained from the models. The models favour phantom behaviour. It is observed that, in presence of dark energy, bulk viscosity has no appreciable effect on the cosmic dynamics.

A mean curvature model for capillary flows in asymmetric containers and conduits

NASA Astrophysics Data System (ADS)

Chen, Yongkang; Tavan, Noël; Weislogel, Mark M.

2012-08-01

Capillarity-driven flows resulting from critical geometric wetting criterion are observed to yield significant shifts of the bulk fluid from one side of the container to the other during "zero gravity" experiments. For wetting fluids, such bulk shift flows consist of advancing and receding menisci sometimes separated by secondary capillary flows such as rivulet-like flows along gaps. Here we study the mean curvature of an advancing meniscus in hopes of approximating a critical boundary condition for fluid dynamics solutions. It is found that the bulk shift flows behave as if the bulk menisci are either "connected" or "disconnected." For the connected case, an analytic method is developed to calculate the mean curvature of the advancing meniscus in an asymptotic sense. In contrast, for the disconnected case the method to calculate the mean curvature of the advancing and receding menisci uses a well-established procedure. Both disconnected and connected bulk shifts can occur as the first tier flow of more complex compound capillary flows. Preliminary comparisons between the analytic method and the results of drop tower experiments are encouraging.

Thermal Conductivity Measurement of Liquids by Using a Suspended Microheater

NASA Astrophysics Data System (ADS)

Oh, Dong-Wook

2017-10-01

In this paper, the traditional 3ω method is modified in order to measure the thermal conductivity of a droplet of liquid. The 3ω sensor is microfabricated using bulk silicon etching on a silicon wafer to form a microheater on a suspended bridge structure. The Si substrate of over 400 μ m thickness beneath the microheater is etched away so that the sample liquid can fill the gap created between the heater and the bottom boundary of the sensor. The frequency of the sinusoidal heating pulses that are generated from the heater is controlled such that the thermal penetration depth is much smaller than the thickness of the liquid layer. The temperature oscillation of the sample fluid is measured at the thin-film heater to calculate the thermal conductivity of the surrounding fluid. The thermal conductivity and measured values of the de-ionized water and ethanol show a good agreement with the theoretical values at room temperature.

Densimetry for the Quantification of Sorption Phenomena on Nonporous Media Near the Dew Point of Fluid Mixtures.

PubMed

Richter, Markus; McLinden, Mark O

2017-07-21

Phase equilibria of fluid mixtures are important in numerous industrial applications and are, thus, a major focus of thermophysical property research. Improved data, particularly along the dew line, are needed to improve model predictions. Here we present experimental results utilizing highly accurate densimetry to quantify the effects of sorption and capillary condensation, which exert a distorting influence on measured properties near the dew line. We investigate the (pressure, density, temperature, composition) behaviour of binary (CH 4  + C 3 H 8 ) and (Ar + CO 2 ) mixtures over the temperature range from (248.15 to 273.15) K starting at low pressures and increasing in pressure towards the dew point along isotherms. Three distinct regions are observed: (1) minor sorption effects in micropores at low pressures; (2) capillary condensation followed by wetting in macro-scale surface scratches beginning approximately 2% below the dew-point pressure; (3) bulk condensation. We hypothesize that the true dew point lies within the second region.

An integrated environmental tracer approach to characterizing groundwater circulation in a mountain block

USGS Publications Warehouse

Manning, Andrew H.; Solomon, D. Kip

2005-01-01

The subsurface transfer of water from a mountain block to an adjacent basin (mountain block recharge (MBR)) is a commonly invoked mechanism of recharge to intermountain basins. However, MBR estimates are highly uncertain. We present an approach to characterize bulk fluid circulation in a mountain block and thus MBR that utilizes environmental tracers from the basin aquifer. Noble gas recharge temperatures, groundwater ages, and temperature data combined with heat and fluid flow modeling are used to identify clearly improbable flow regimes in the southeastern Salt Lake Valley, Utah, and adjacent Wasatch Mountains. The range of possible MBR rates is reduced by 70%. Derived MBR rates (5.5–12.6 × 104 m3 d−1) are on the same order of magnitude as previous large estimates, indicating that significant MBR to intermountain basins is plausible. However, derived rates are 50–100% of the lowest previous estimate, meaning total recharge is probably less than previously thought.

Temperature dependence of the structural relaxation time in equilibrium below the nominal T(g): results from freestanding polymer films.

PubMed

Ngai, K L; Capaccioli, Simone; Paluch, Marian; Prevosto, Daniele

2014-05-22

When the thickness is reduced to nanometer scale, freestanding high molecular weight polymer thin films undergo large reduction of degree of cooperativity and coupling parameter n in the Coupling Model (CM). The finite-size effect together with the surfaces with high mobility make the α-relaxation time of the polymer in nanoconfinement, τ(α)(nano)(T), much shorter than τ(α)(bulk)(T) in the bulk. The consequence is avoidance of vitrification at and below the bulk glass transition temperature, T(g)(bulk), on cooling, and the freestanding polymer thin film remains at thermodynamic equilibrium at temperatures below T(g)(bulk). Molecular dynamics simulations have shown that the specific volume of the freestanding film is the same as the bulk glass-former at equilibrium at the same temperatures. Extreme nanoconfinement renders total or almost total removal of cooperativity of the α-relaxation, and τ(α)(nano)(T) becomes the same or almost the same as the JG β-relaxation time τ(β)(bulk)(T) of the bulk glass-former at equilibrium and at temperatures below T(g)(bulk). Taking advantage of being able to obtain τ(β)(bulk)(T) at equilibrium density below T(g)(bulk) by extreme nanoconfinement of the freestanding films, and using the CM relation between τ(α)(bulk)(T) and τ(β)(bulk)(T), we conclude that the Vogel-Fulcher-Tammann-Hesse (VFTH) dependence of τ(α)(bulk)(T) cannot hold for glass-formers in equilibrium at temperatures significantly below T(g)(bulk). In addition, τ(α)(bulk)(T) does not diverge at the Vogel temperature, T₀, as suggested by the VFTH-dependence and predicted by some theories of glass transition. Instead, τ(α)(bulk)(T) of the glass-former at equilibrium has a much weaker temperature dependence than the VFTH-dependence at temperature below T(g)(bulk) and even below T₀. This conclusion from our analysis is consistent with the temperature dependence of τ(α)(bulk)(T) found experimentally in polymers aged long enough time to attain the equilibrium state at various temperatures below T(g)(bulk).

Process for heating coal-oil slurries

DOEpatents

Braunlin, W.A.; Gorski, A.; Jaehnig, L.J.; Moskal, C.J.; Naylor, J.D.; Parimi, K.; Ward, J.V.

1984-01-03

Controlling gas to slurry volume ratio to achieve a gas holdup of about 0.4 when heating a flowing coal-oil slurry and a hydrogen containing gas stream allows operation with virtually any coal to solvent ratio and permits operation with efficient heat transfer and satisfactory pressure drops. The critical minimum gas flow rate for any given coal-oil slurry will depend on numerous factors such as coal concentration, coal particle size distribution, composition of the solvent (including recycle slurries), and type of coal. Further system efficiency can be achieved by operating with multiple heating zones to provide a high heat flux when the apparent viscosity of the gas saturated slurry is highest. Operation with gas flow rates below the critical minimum results in system instability indicated by temperature excursions in the fluid and at the tube wall, by a rapid increase and then decrease in overall pressure drop with decreasing gas flow rate, and by increased temperature differences between the temperature of the bulk fluid and the tube wall. At the temperatures and pressures used in coal liquefaction preheaters the coal-oil slurry and hydrogen containing gas stream behaves essentially as a Newtonian fluid at shear rates in excess of 150 sec[sup [minus]1]. The gas to slurry volume ratio should also be controlled to assure that the flow regime does not shift from homogeneous flow to non-homogeneous flow. Stable operations have been observed with a maximum gas holdup as high as 0.72. 29 figs.

Process for heating coal-oil slurries

DOEpatents

Braunlin, Walter A.; Gorski, Alan; Jaehnig, Leo J.; Moskal, Clifford J.; Naylor, Joseph D.; Parimi, Krishnia; Ward, John V.

1984-01-03

Controlling gas to slurry volume ratio to achieve a gas holdup of about 0.4 when heating a flowing coal-oil slurry and a hydrogen containing gas stream allows operation with virtually any coal to solvent ratio and permits operation with efficient heat transfer and satisfactory pressure drops. The critical minimum gas flow rate for any given coal-oil slurry will depend on numerous factors such as coal concentration, coal particle size distribution, composition of the solvent (including recycle slurries), and type of coal. Further system efficiency can be achieved by operating with multiple heating zones to provide a high heat flux when the apparent viscosity of the gas saturated slurry is highest. Operation with gas flow rates below the critical minimum results in system instability indicated by temperature excursions in the fluid and at the tube wall, by a rapid increase and then decrease in overall pressure drop with decreasing gas flow rate, and by increased temperature differences between the temperature of the bulk fluid and the tube wall. At the temperatures and pressures used in coal liquefaction preheaters the coal-oil slurry and hydrogen containing gas stream behaves essentially as a Newtonian fluid at shear rates in excess of 150 sec.sup. -1. The gas to slurry volume ratio should also be controlled to assure that the flow regime does not shift from homogeneous flow to non-homogeneous flow. Stable operations have been observed with a maximum gas holdup as high as 0.72.

Temperature Effect on Micelle Formation: Molecular Thermodynamic Model Revisited.

PubMed

Khoshnood, Atefeh; Lukanov, Boris; Firoozabadi, Abbas

2016-03-08

Temperature affects the aggregation of macromolecules such as surfactants, polymers, and proteins in aqueous solutions. The effect on the critical micelle concentration (CMC) is often nonmonotonic. In this work, the effect of temperature on the micellization of ionic and nonionic surfactants in aqueous solutions is studied using a molecular thermodynamic model. Previous studies based on this technique have predicted monotonic behavior for ionic surfactants. Our investigation shows that the choice of tail transfer energy to describe the hydrophobic effect between the surfactant tails and the polar solvent molecules plays a key role in the predicted CMC. We modify the tail transfer energy by taking into account the effect of the surfactant head on the neighboring methylene group. The modification improves the description of the CMC and the predicted micellar size for aqueous solutions of sodium n-alkyl sulfate, dodecyl trimethylammonium bromide (DTAB), and n-alkyl polyoxyethylene. The new tail transfer energy describes the nonmonotonic behavior of CMC versus temperature. In the DTAB-water system, we redefine the head size by including the methylene group, next to the nitrogen, in the head. The change in the head size along with our modified tail transfer energy improves the CMC and aggregation size prediction significantly. Tail transfer is a dominant energy contribution in micellar and microemulsion systems. It also promotes the adsorption of surfactants at fluid-fluid interfaces and affects the formation of adsorbed layer at fluid-solid interfaces. Our proposed modifications have direct applications in the thermodynamic modeling of the effect of temperature on molecular aggregation, both in the bulk and at the interfaces.

Molecular simulation of CO chemisorption on Co(0001) in presence of supercritical fluid solvent: A potential of mean force study

NASA Astrophysics Data System (ADS)

Asiaee, Alireza; Benjamin, Kenneth M.

2016-08-01

For several decades, heterogeneous catalytic processes have been improved through utilizing supercritical fluids (SCFs) as solvents. While numerous experimental studies have been established across a range of chemistries, such as oxidation, pyrolysis, amination, and Fischer-Tropsch synthesis, still there is little fundamental, molecular-level information regarding the role of the SCF on elementary heterogeneous catalytic steps. In this study, the influence of hexane solvent on the adsorption of carbon monoxide on Co(0001), as the first step in the reaction mechanism of many processes involving syngas conversion, is probed. Simulations are performed at various bulk hexane densities, ranging from ideal gas conditions (no SCF hexane) to various near- and super-critical hexane densities. For this purpose, both density functional theory and molecular dynamics simulations are employed to determine the adsorption energy and free energy change during CO chemisorption. Potential of mean force calculations, utilizing umbrella sampling and the weighted histogram analysis method, provide the first commentary on SCF solvent effects on the energetic aspects of the chemisorption process. Simulation results indicate an enhanced stability of CO adsorption on the catalyst surface in the presence of supercritical hexane within the reduced pressure range of 1.0-1.5 at a constant temperature of 523 K. Furthermore, it is shown that the maximum stability of CO in the adsorbed state as a function of supercritical hexane density at 523 K nearly coincides with the maximum isothermal compressibility of bulk hexane at this temperature.

Radiating gravitational collapse with shearing motion and bulk viscosity

NASA Astrophysics Data System (ADS)

Chan, R.

2001-03-01

A model is proposed of a collapsing radiating star consisting of a shearing fluid with bulk viscosity undergoing radial heat flow with outgoing radiation. The pressure of the star, at the beginning of the collapse, is isotropic but due to the presence of the bulk viscosity the pressure becomes more and more anisotropic. The behavior of the density, pressure, mass, luminosity, the effective adiabatic index and the Kretschmann scalar is analyzed. Our work is compared to the case of a collapsing shearing fluid of a previous model, for a star with 6 Msun.

Heat of adsorption, adsorption stress, and optimal storage of methane in slit and cylindrical carbon pores predicted by classical density functional theory.

PubMed

Hlushak, Stepan

2018-01-03

Temperature, pressure and pore-size dependences of the heat of adsorption, adsorption stress, and adsorption capacity of methane in simple models of slit and cylindrical carbon pores are studied using classical density functional theory (CDFT) and grand-canonical Monte-Carlo (MC) simulation. Studied properties depend nontrivially on the bulk pressure and the size of the pores. Heat of adsorption increases with loading, but only for sufficiently narrow pores. While the increase is advantageous for gas storage applications, it is less significant for cylindrical pores than for slits. Adsorption stress and the average adsorbed fluid density show oscillatory dependence on the pore size and increase with bulk pressure. Slit pores exhibit larger amplitude of oscillations of the normal adsorption stress with pore size increase than cylindrical pores. However, the increase of the magnitude of the adsorption stress with bulk pressure increase is more significant for cylindrical than for slit pores. Adsorption stress appears to be negative for a wide range of pore sizes and external conditions. The pore size dependence of the average delivered density of the gas is analyzed and the optimal pore sizes for storage applications are estimated. The optimal width of slit pore appears to be almost independent of storage pressure at room temperature and pressures above 10 bar. Similarly to the case of slit pores, the optimal radius of cylindrical pores does not exhibit much dependence on the storage pressure above 15 bar. Both optimal width and optimal radii of slit and cylindrical pores increase as the temperature decreases. A comparison of the results of CDFT theory and MC simulations reveals subtle but important differences in the underlying fluid models employed by the approaches. The differences in the high-pressure behaviour between the hard-sphere 2-Yukawa and Lennard-Jones models of methane, employed by the CDFT and MC approaches, respectively, result in an overestimation of the heat of adsorption by the CDFT theory at higher loadings. However, both adsorption stress and adsorption capacity appear to be much less sensitive to the differences between the models and demonstrate excellent agreement between the theory and the computer experiment.

Glycerol in micellar confinement with tunable rigidity

NASA Astrophysics Data System (ADS)

Lannert, Michael; Müller, Allyn; Gouirand, Emmanuel; Talluto, Vincenzo; Rosenstihl, Markus; Walther, Thomas; Stühn, Bernd; Blochowicz, Thomas; Vogel, Michael

2016-12-01

We investigate the glassy dynamics of glycerol in the confinement of a microemulsion system, which is stable on cooling down to the glass transition of its components. By changing the composition, we vary the viscosity of the matrix, while keeping the confining geometry intact, as is demonstrated by small angle X-ray scattering. By means of 2H NMR, differential scanning calorimetry, and triplet solvation dynamics we, thus, probe the dynamics of glycerol in confinements of varying rigidity. 2H NMR results show that, at higher temperatures, the dynamics of confined glycerol is unchanged compared to bulk behavior, while the reorientation of glycerol molecules becomes significantly faster than in the bulk in the deeply supercooled regime. However, comparison of different 2H NMR findings with data from calorimetry and solvation dynamics reveals that this acceleration is not due to the changed structural relaxation of glycerol, but rather due to the rotational motion of essentially rigid glycerol droplets or of aggregates of such droplets in a more fluid matrix. Thus, independent of the matrix mobility, the glycerol dynamics remains unchanged except for the smallest droplets, where an increase of Tg and, thus, a slowdown of the structural relaxation is observed even in a fluid matrix.

Why coronal flux tubes have axially invariant cross-section

NASA Astrophysics Data System (ADS)

Bellan, Paul

2001-10-01

We present here a model that not only explains the long-standing mystery^1 of why solar coronal flux tubes tend towards having axially invariant cross-sections but also explains several other enigmatic features, namely: rotating jets emanating from the ends (surges), counter-streaming beams, ingestion of photospheric material, and elevated pressure/temperature compared to adjacent plasma. The model shows that when a steady current flows along a flux tube with a bulging middle (i.e., a flux tube that is initially produced by a potential magnetic field), non-conservative forces develop which accelerate fluid axially from both ends towards the middle. Remarkably, this axial pumping of fluid into the flux tube causes the flux tube cross-section and volume to decrease in a manner such that the flux tube develops an axial uniform cross-section as observed in coronal loops. The pumping process produces counter-rotating, counter-streaming Alfvenic bulk motion consistent with observations. Collision of the counter-streaming beams causes non-localized bulk heating. This picture also has relevance to astrophysical jets and coaxial spheromak guns and explains why these systems tend to form an axial jet along the geometric axis. Supported by USDOE. l ^1 J. A. Klimchuk, Solar Phys. 193, 53 (2000)

Why coronal flux tubes have axially invariant cross-section

NASA Astrophysics Data System (ADS)

Bellan, P. M.

2001-12-01

We present here a model that not only explains the long-standing mystery of why solar coronal flux tubes tend towards having axially in-variant cross-sections but also explains several other enigmatic features, namely: rotating jets emanating from the ends (surges), counter-streaming beams, ingestion of photospheric material, and elevated pressure/temperature compared to adjacent plasma. The model shows that when a steady current flows along a flux tube with a bulging middle (i.e., a flux tube that is initially produced by a potential magnetic field), non-conservative forces develop which accelerate fluid axially from both ends towards the middle. Remarkably, this axial pumping of fluid into the flux tube causes the flux tube cross-section and volume to decrease in a manner such that the flux tube develops an axial uniform cross-section as observed in coronal loops. The pumping process produces counter-rotating, counter-streaming Alfvenic bulk motion consistent with observations. Collision of the counter-streaming beams causes non-localized bulk heating. This picture also has relevance to astrophysical jets and coaxial spheromak guns and explains why these systems tend to form an axial jet along the geometric axis. Supported by USDOE. [1]J. A. Klimchuk, Solar Phys. 193, 53 (2000)

Investigation of Instabilities and Heat Transfer Phenomena in Supercritical Fuels at High Heat Flux and Temperatures

NASA Technical Reports Server (NTRS)

Linne, Diane L.; Meyer, Michael L.; Braun, Donald C.; Keller, Dennis J.

2000-01-01

A series of heated tube experiments was performed to investigate fluid instabilities that occur during heating of supercritical fluids. In these tests, JP-7 flowed vertically through small diameter tubes at supercritical pressures. Test section heated length, diameter, mass flow rate, inlet temperature, and heat flux were varied in an effort to determine the range of conditions that trigger the instabilities. Heat flux was varied up to 4 BTU/sq in./s, and test section wall temperatures reached as high as 1950 F. A statistical model was generated to explain the trends and effects of the control variables. The model included no direct linear effect of heat flux on the occurrence of the instabilities. All terms involving inlet temperature were negative, and all terms involving mass flow rate were positive. Multiple tests at conditions that produced instabilities provided inconsistent results. These inconsistencies limit the use of the model as a predictive tool. Physical variables that had been previously postulated to control the onset of the instabilities, such as film temperature, velocity, buoyancy, and wall-to-bulk temperature ratio, were evaluated here. Film temperatures at or near critical occurred during both stable and unstable tests. All tests at the highest velocity were stable, but there was no functional relationship found between the instabilities and velocity, or a combination of velocity and temperature ratio. Finally, all of the unstable tests had significant buoyancy at the inlet of the test section, but many stable tests also had significant buoyancy forces.

Scaling Analysis of Alloy Solidification and Fluid Flow in a Rectangular Cavity

NASA Astrophysics Data System (ADS)

Plotkowski, A.; Fezi, K.; Krane, M. J. M.

A scaling analysis was performed to predict trends in alloy solidification in a side-cooled rectangular cavity. The governing equations for energy and momentum were scaled in order to determine the dependence of various aspects of solidification on the process parameters for a uniform initial temperature and an isothermal boundary condition. This work improved on previous analyses by adding considerations for the cooling bulk fluid flow. The analysis predicted the time required to extinguish the superheat, the maximum local solidification time, and the total solidification time. The results were compared to a numerical simulation for a Al-4.5 wt.% Cu alloy with various initial and boundary conditions. Good agreement was found between the simulation results and the trends predicted by the scaling analysis.

Kaluza-Klein Bulk Viscous Fluid Cosmological Models and the Validity of the Second Law of Thermodynamics in f(R, T) Gravity

NASA Astrophysics Data System (ADS)

Samanta, Gauranga Charan; Myrzakulov, Ratbay; Shah, Parth

2017-04-01

The authors considered the bulk viscous fluid in f(R, T) gravity within the framework of Kaluza-Klein space time. The bulk viscous coefficient (ξ) expressed as ξ = {ξ_0} + {ξ_1}{{\\dot a} \\over a} + {ξ_2}{{\\ddot a} \\over {\\dot a}}, where ξ0, ξ1, and ξ2 are positive constants. We take p=(γ-1)ρ, where 0≤γ≤2 as an equation of state for perfect fluid. The exact solutions to the corresponding field equations are given by assuming a particular model of the form of f(R, T)=R+2f(T), where f(T)=λT, λ is constant. We studied the cosmological model in two stages, in first stage: we studied the model with no viscosity, and in second stage: we studied the model involve with viscosity. The cosmological model involve with viscosity is studied by five possible scenarios for bulk viscous fluid coefficient (ξ). The total bulk viscous coefficient seems to be negative, when the bulk viscous coefficient is proportional to {ξ _2}{{\\ddot a} \\over {\\dot a}}, hence, the second law of thermodynamics is not valid; however, it is valid with the generalised second law of thermodynamics. The total bulk viscous coefficient seems to be positive, when the bulk viscous coefficient is proportional to ξ = {ξ _1}{{\\dot a} \\over a} + {ξ _2}{{\\ddot a} \\over {\\dot a}} and ξ = {ξ _0} + {ξ _1}{{\\dot a} \\over a} + {ξ _2}{{\\ddot a} \\over {\\dot a}}, so the second law of thermodynamics and the generalised second law of thermodynamics is satisfied throughout the evolution. We calculate statefinder parameters of the model and observed that it is different from the ∧CDM model. Finally, some physical and geometrical properties of the models are discussed.

Statistical mechanics of homogeneous partly pinned fluid systems.

PubMed

Krakoviack, Vincent

2010-12-01

The homogeneous partly pinned fluid systems are simple models of a fluid confined in a disordered porous matrix obtained by arresting randomly chosen particles in a one-component bulk fluid or one of the two components of a binary mixture. In this paper, their configurational properties are investigated. It is shown that a peculiar complementarity exists between the mobile and immobile phases, which originates from the fact that the solid is prepared in presence of and in equilibrium with the adsorbed fluid. Simple identities follow, which connect different types of configurational averages, either relative to the fluid-matrix system or to the bulk fluid from which it is prepared. Crucial simplifications result for the computation of important structural quantities, both in computer simulations and in theoretical approaches. Finally, possible applications of the model in the field of dynamics in confinement or in strongly asymmetric mixtures are suggested.

Rotary adsorbers for continuous bulk separations

DOEpatents

Baker, Frederick S [Oak Ridge, TN

2011-11-08

A rotary adsorber for continuous bulk separations is disclosed. The rotary adsorber includes an adsorption zone in fluid communication with an influent adsorption fluid stream, and a desorption zone in fluid communication with a desorption fluid stream. The fluid streams may be gas streams or liquid streams. The rotary adsorber includes one or more adsorption blocks including adsorbent structure(s). The adsorbent structure adsorbs the target species that is to be separated from the influent fluid stream. The apparatus includes a rotary wheel for moving each adsorption block through the adsorption zone and the desorption zone. A desorption circuit passes an electrical current through the adsorbent structure in the desorption zone to desorb the species from the adsorbent structure. The adsorbent structure may include porous activated carbon fibers aligned with their longitudinal axis essentially parallel to the flow direction of the desorption fluid stream. The adsorbent structure may be an inherently electrically-conductive honeycomb structure.

Explosively driven low-density foams and powders

DOEpatents

Viecelli, James A [Orinda, CA; Wood, Lowell L [Simi Valley, CA; Ishikawa, Muriel Y [Livermore, CA; Nuckolls, John H [Danville, CA; Pagoria, Phillip F [Livermore, CA

2010-05-04

Hollow RX-08HD cylindrical charges were loaded with boron and PTFE, in the form of low-bulk density powders or powders dispersed in a rigid foam matrix. Each charge was initiated by a Comp B booster at one end, producing a detonation wave propagating down the length of the cylinder, crushing the foam or bulk powder and collapsing the void spaces. The PdV work done in crushing the material heated it to high temperatures, expelling it in a high velocity fluid jet. In the case of boron particles supported in foam, framing camera photos, temperature measurements, and aluminum witness plates suggest that the boron was completely vaporized by the crush wave and that the boron vapor turbulently mixed with and burned in the surrounding air. In the case of PTFE powder, X-ray photoelectron spectroscopy of residues recovered from fragments of a granite target slab suggest that heating was sufficient to dissociate the PTFE to carbon vapor and molecular fluorine which reacted with the quartz and aluminum silicates in the granite to form aluminum oxide and mineral fluoride compounds.

Progressive serpentinization of the oceanic lithosphere from ridge to ridge flank: Consequences for biogeochemical cycles

NASA Astrophysics Data System (ADS)

Frueh-Green, G. L.; Boschi, C.

2011-12-01

Exposure of mantle rocks is an integral process of slow- and ultra-slow spreading ridges and ridge-flanks. Mantle-dominated lithosphere is a highly reactive chemical and thermal system, in which progressive interaction with seawater during serpentinization has significant geophysical, geochemical and biological consequences for the global marine system. This presentation is intended to provide an overview of serpentinization processes as fundamental to understanding the evolution of oceanic lithosphere formed at slow spreading ridges, fluid flow and the consequences of serpentinization for biogeochemical cycles. Seawater progressively reacts with peridotite, commonly as detachment faults unroof mantle material to the seafloor and serpentinites become dominant components of the ridge flanks. The mineral assemblages and textures of abyssal serpentinites typically record progressive, static hydration reactions that take place under a wide range of temperatures, lithospheric depths, fluid compositions and redox conditions. The products and sequence of serpentinization reactions are influenced by the time-integrated flux of seawater, bulk protolith compositions, the presence or absence of magmatic intrusions and/or trapped gabbroic melts, and structure (e.g., detachment faults, cataclastic fault zones). In turn, these factors influence mineral assemblages, fluid chemistry, and volatile contents. Serpentinization processes have major consequences for long-term, global geochemical fluxes by acting as a sink for H2O, Cl, B, U, S, and C from seawater and a source of Ca, Ni and possibly Cr to hydrothermal fluids, and by producing hydrogen-rich reduced fluids that are critical to sustain microbial communities. Seafloor weathering of serpentinized abyssal peridotites may also result in Mg loss and enhanced B uptake during clay mineral formation. The production of hydrogen during serpentinization is generally attributed to the formation of magnetite during olivine hydration and is described by simplified reactions with end-member phases. In reality, serpentinization involves solid solutions and metastable reactions governed by local variations in bulk chemistry, fluid-rock ratios and the activities of elements such as Si, Mg, Fe, Ca, and C. Serpentinization at temperatures below ~200°C produces high alkaline, Ca-rich fluids with elevated concentrations of abiotic hydrocarbons and formate, as exemplified by the Lost City hydrothermal system [1,2]. The high pH and reducing conditions dictate that any carbonate species in the fluids are either reduced or precipitated as carbonate before fluid discharge on the seafloor, and thus represents an important sink of dissolved (inorganic and organic) carbon from seawater [2,3]. In contrast to basalt-dominated ridge flank systems, where conceptual models of the fluid pathways and subsequent reactions and element uptake are relatively well constrained, less is known of the fluid flow and reaction paths in serpentinite-dominated portions of ridge flanks at slow- and ultra-slow spreading environments. [1] Kelley et al. (2005) Science 307, 1428-1434. [2] Proskurowski et al. (2008) Science 319, 604-607. [3] Delacour et al. (2008) GCA 72, 3681-3702.

Transport coefficients and heat fluxes in non-equilibrium high-temperature flows with electronic excitation

NASA Astrophysics Data System (ADS)

Istomin, V. A.; Kustova, E. V.

2017-02-01

The influence of electronic excitation on transport processes in non-equilibrium high-temperature ionized mixture flows is studied. Two five-component mixtures, N 2 / N2 + / N / N + / e - and O 2 / O2 + / O / O + / e - , are considered taking into account the electronic degrees of freedom for atomic species as well as the rotational-vibrational-electronic degrees of freedom for molecular species, both neutral and ionized. Using the modified Chapman-Enskog method, the transport coefficients (thermal conductivity, shear viscosity and bulk viscosity, diffusion and thermal diffusion) are calculated in the temperature range 500-50 000 K. Thermal conductivity and bulk viscosity coefficients are strongly affected by electronic states, especially for neutral atomic species. Shear viscosity, diffusion, and thermal diffusion coefficients are not sensible to electronic excitation if the size of excited states is assumed to be constant. The limits of applicability for the Stokes relation are discussed; at high temperatures, this relation is violated not only for molecular species but also for electronically excited atomic gases. Two test cases of strongly non-equilibrium flows behind plane shock waves corresponding to the spacecraft re-entry (Hermes and Fire II) are simulated numerically. Fluid-dynamic variables and heat fluxes are evaluated in gases with electronic excitation. In inviscid flows without chemical-radiative coupling, the flow-field is weakly affected by electronic states; however, in viscous flows, their influence can be more important, in particular, on the convective heat flux. The contribution of different dissipative processes to the heat transfer is evaluated as well as the effect of reaction rate coefficients. The competition of diffusion and heat conduction processes reduces the overall effect of electronic excitation on the convective heating, especially for the Fire II test case. It is shown that reliable models of chemical reaction rates are of great importance for accurate predictions of the fluid dynamic variables and heat fluxes.

Oxygen Isotopes and the Cooling History of the Mount Barcroft Area, Central White Mountains, Easternmost California

NASA Astrophysics Data System (ADS)

Ernst, W. G.; Rumble, D.

2001-12-01

The White-Inyo Range + Owens Valley marks the western limit of the Basin and Range province, directly east of the Sierra Nevada. At Mount Barcroft, mid-Mesozoic, alkaline, bimodal White Mountain Peak metavolcanic + metaclastic rocks on the N are separated from Lower Cambrian siliciclastic + carbonate metasedimentary strata on the S by the NE-trending Middle Jurassic Barcroft mafic granodioritic pluton. It consists of mineralogically/chemically intergradational gabbro/diorite, granodiorite, metadiorite, and alaskite. Eastward, the section is intruded by the Late Cretaceous, ternary-minimum McAfee Creek Granite. Ignoring altered dikes, bulk-rock analyses of plutonic rocks indicate that metaluminous, I-type rocks of the Barcroft comagmatic suite possess an av(12) d18O value of 7.5. Slightly peraluminous, apparently S-type granitic rocks sensu stricto of the McAfee Creek series have an av(8) d18O value of 8.6. Evidence is lacking for large-scale bulk-rock interaction with near-surface waters, suggesting intermediate crustal depths of intrusion and cooling for these plutons. Coexisting Barcroft minerals exhibit consistent oxygen isotopic partitioning from high to low d18O in the sequence quartz > plagioclase > K-feldspar >> amphibole = biotite. Wall-rock quartz and biotite are richer in 18O than analogous phases in the plutonic rocks, and show slightly greater fractionations than igneous counterparts. Along its borders, late-stage exchange with heated aqueous fluids, derived from recrystallized wall rocks due to emplacement of the Middle Jurassic magma, increased 18O/16O ratios of dikes, and some Barcroft igneous plagioclase and subsolidus tremolite-actinolite. Oxygen isotope geothermometry for Barcroft quartz-amphibole and quartz-biotite pairs yields broadly similar temperatures; the combined average of 13 pairs is 519oC. A single quartz-biotite pair analyzed from a Lower Cambrian quartzite within the inner metamorphic aureole of the Barcroft pluton yields a temperature of 511oC, in agreement with values based on wall-rock metamorphic parageneses. Barcroft quartz, feldspars, biotite, and clinoamphiboles were subjected to exchange with deuteric fluid, and re-equilibrated under subsolidus conditions. Quartz-plagioclase pairs from two Barcroft granodiorites possess similar temperatures of 519 and 515oC, so also re-equilibrated at subsolidus temperatures. Areal distributions for quartz-plagioclase, quartz-clinoamphibole, and quartz-biotite pairs reveal that annealing temperatures are lowest in axial portions of the Barcroft granodioritic pluton. Late Cretaceous emplacement of the McAfee Creek Granite had little effect on d18O values of Barcroft minerals and bulk rocks.

Prediction of forced convective heat transfer and critical heat flux for subcooled water flowing in miniature tubes

NASA Astrophysics Data System (ADS)

Shibahara, Makoto; Fukuda, Katsuya; Liu, Qiusheng; Hata, Koichi

2018-02-01

The heat transfer characteristics of forced convection for subcooled water in small tubes were clarified using the commercial computational fluid dynamic (CFD) code, PHENICS ver. 2013. The analytical model consists of a platinum tube (the heated section) and a stainless tube (the non-heated section). Since the platinum tube was heated by direct current in the authors' previous experiments, a uniform heat flux with the exponential function was given as a boundary condition in the numerical simulation. Two inner diameters of the tubes were considered: 1.0 and 2.0 mm. The upward flow velocities ranged from 2 to 16 m/s and the inlet temperature ranged from 298 to 343 K. The numerical results showed that the difference between the surface temperature and the bulk temperature was in good agreement with the experimental data at each heat flux. The numerical model was extended to the liquid sublayer analysis for the CHF prediction and was evaluated by comparing its results with the experimental data. It was postulated that the CHF occurs when the fluid temperature near the heated wall exceeds the saturated temperature, based on Celata et al.'s superheated layer vapor replenishment (SLVR) model. The suggested prediction method was in good agreement with the experimental data and with other CHF data in literature within ±25%.

To what extent is water responsible for the maintenance of the life for warm-blooded organisms?

PubMed

Fisenko, Anatoliy I; Malomuzh, Nikolay P

2009-05-22

In this work, attention is mainly focused on those properties of water which are essentially changed in the physiological temperature range of warm-blooded organisms. Studying in detail the half-width of the diffusion peak in the quasi-elastic incoherent neutron scattering, the behavior of the entropy and the kinematic shear viscosity, it is shown that the character of the translational and rotational thermal motions in water radically change near T(H) ~ 315 K, which can be interpreted as the temperature of the smeared dynamic phase transition. These results for bulk pure water are completed by the analysis of the isothermic compressibility and the NMR-spectra for water-glycerol solutions. It was noted that the non-monotone temperature dependence of the isothermic compressibility (beta(T)) takes also place for the water-glycerol solutions until the concentration of glycerol does not exceed 30 mol%. At that, the minimum of beta(T) shifts at left when the concentration increases. All these facts give us some reasons to assume that the properties of the intracellular and extracellular fluids are close to ones for pure water. Namely therefore, we suppose that the upper temperature limit for the life of warm-blooded organisms [T(D) = (315 +/- 3) K] is tightly connected with the temperature of the dynamic phase transition in water. This supposition is equivalent to the assertion that the denaturation of proteins at T > or = T(H) is mainly provoked by the rebuilding of the H-bond network in the intracellular and extracellular fluids, which takes place at T > or = T(H). A question why the heavy water cannot be a matrix for the intracellular and extracellular fluids is considered. The lower physiological pH limit for the life of warm-blooded organisms is discussed.

The Sensitivity of Aragonite U/Ca Ratio to Seawater Carbonate Ion Concentration: Insight From Abiogenic Precipitation Experiments and Application to Coral Biomineralization

NASA Astrophysics Data System (ADS)

Decarlo, T. M.; Gaetani, G. A.; Holcomb, M.; Cohen, A. L.

2014-12-01

The U/Ca ratio of aragonite coral skeleton has been shown to correlate with both temperature and seawater carbonate chemistry. However, U/Ca has not been conclusively linked to carbonate chemistry and/or temperature in laboratory experiments. We have performed abiogenic precipitation experiments designed to evaluate the sensitivity of U partitioning between aragonite and seawater to temperature, pH, and the concentration of carbonate ion in seawater. Aragonite was precipitated from seawater by addition of carbonate alkalinity at rates set to maintain stable carbonate chemistry during precipitation. Experiments were conducted between 20-40 °C, pH 7.8-9.0, and carbonate ion concentration 600-2600 μmol kg-1. Mineralogies of the precipitates were identified by Raman spectrometry and U/Ca ratios of the bulk precipitate and fluid were determined by solution ICP-MS. Our results show that the U/Ca ratio of aragonite precipitated from an infinite reservoir of seawater decreases with increasing carbonate ion concentration, and is independent of pH and temperature. Using our abiogenic results as a basis for interpreting coral skeletal chemistry, we model the coral biomineralization process to show that the U/Ca ratio of coral skeleton reflects a calcifying fluid with carbonate ion concentration of at least 1000 μmol kg-1, several times greater than ambient seawater. Further, we show that the coral biomineralization response to environmental changes can be linked to changes in calcifying fluid composition via skeletal U/Ca ratios.

The influence of topology on hydraulic conductivity in a sand-and-gravel aquifer.

PubMed

Morin, Roger H; LeBlanc, Denis R; Troutman, Brent M

2010-01-01

A field experiment consisting of geophysical logging and tracer testing was conducted in a single well that penetrated a sand-and-gravel aquifer at the U.S. Geological Survey Toxic Substances Hydrology research site on Cape Cod, Massachusetts. Geophysical logs and flowmeter/pumping measurements were obtained to estimate vertical profiles of porosity phi, hydraulic conductivity K, temperature, and bulk electrical conductivity under background, freshwater conditions. Saline-tracer fluid was then injected into the well for 2 h and its radial migration into the surrounding deposits was monitored by recording an electromagnetic-induction log every 10 min. The field data are analyzed and interpreted primarily through the use of Archie's (1942) law to investigate the role of topological factors such as pore geometry and connectivity, and grain size and packing configuration in regulating fluid flow through these coarse-grained materials. The logs reveal no significant correlation between K and phi, and imply that groundwater models that link these two properties may not be useful at this site. Rather, it is the distribution and connectivity of the fluid phase as defined by formation factor F, cementation index m, and tortuosity alpha that primarily control the hydraulic conductivity. Results show that F correlates well with K, thereby indicating that induction logs provide qualitative information on the distribution of hydraulic conductivity. A comparison of alpha, which incorporates porosity data, with K produces only a slightly better correlation and further emphasizes the weak influence of the bulk value of varphi on K.

Enthalpy-based equation of state for highly porous materials employing modified soft sphere fluid model

NASA Astrophysics Data System (ADS)

Nayak, Bishnupriya; Menon, S. V. G.

2018-01-01

Enthalpy-based equation of state based on a modified soft sphere model for the fluid phase, which includes vaporization and ionization effects, is formulated for highly porous materials. Earlier developments and applications of enthalpy-based approach had not accounted for the fact that shocked states of materials with high porosity (e.g., porosity more than two for Cu) are in the expanded fluid region. We supplement the well known soft sphere model with a generalized Lennard-Jones formula for the zero temperature isotherm, with parameters determined from cohesive energy, specific volume and bulk modulus of the solid at normal condition. Specific heats at constant pressure, ionic and electronic enthalpy parameters and thermal excitation effects are calculated using the modified approach and used in the enthalpy-based equation of state. We also incorporate energy loss from the shock due to expansion of shocked material in calculating porous Hugoniot. Results obtained for Cu, even up to initial porosities ten, show good agreement with experimental data.

Local equilibrium solutions in simple anisotropic cosmological models, as described by relativistic fluid dynamics

NASA Astrophysics Data System (ADS)

Shogin, Dmitry; Amund Amundsen, Per

2016-10-01

We test the physical relevance of the full and the truncated versions of the Israel-Stewart (IS) theory of irreversible thermodynamics in a cosmological setting. Using a dynamical systems method, we determine the asymptotic future of plane symmetric Bianchi type I spacetimes with a viscous mathematical fluid, keeping track of the magnitude of the relative dissipative fluxes, which determines the applicability of the IS theory. We consider the situations where the dissipative mechanisms of shear and bulk viscosity are involved separately and simultaneously. It is demonstrated that the only case in the given model when the fluid asymptotically approaches local thermal equilibrium, and the underlying assumptions of the IS theory are therefore not violated, is that of a dissipative fluid with vanishing bulk viscosity. The truncated IS equations for shear viscosity are found to produce solutions which manifest pathological dynamical features and, in addition, to be strongly sensitive to the choice of initial conditions. Since these features are observed already in the case of an oversimplified mathematical fluid model, we have no reason to assume that the truncation of the IS transport equations will produce relevant results for physically more realistic fluids. The possible role of bulk and shear viscosity in cosmological evolution is also discussed.

Experimental investigation and numerical simulation of a copper micro-channel heat exchanger with HFE-7200 working fluid

NASA Astrophysics Data System (ADS)

Borquist, Eric

Ever increasing cost and consumption of global energy resources has inspired the development of energy harvesting techniques which increase system efficiency, sustainability, and environmental impact by using waste energy otherwise lost to the surroundings. As part of a larger effort to produce a multi-energy source prototype, this study focused on the fabrication and testing of a waste heat recovery micro-channel heat exchanger. Reducing cost and facility requirements were a priority for potential industry and commercial adoption of such energy harvesting devices. During development of the micro-channel heat exchanger, a new fabrication process using mature technologies was created that reduced cost, time, and required equipment. Testing involved filling the micro-channel heat exchanger with 3MTM NovecTM HFE-7200 working fluid. The working fluid was chosen for appropriate physical and environmental properties for the prototypes intended application. Using a dry heat exchanger as the baseline, the addition of the working fluid proved advantageous by increasing energy output by 8% while decreasing overall device temperatures. Upon successful experimental testing of the physical device, internal operation was determined based on implementation of the lattice Boltzmann method, a physics-based statistical method that actively tracked the phase change occurring in a simulated micro-channel. The simulation demonstrated three primary areas of phase change occurring, surfaces adjacent to where the heat source and heat sink were located and the bulk vapor-liquid interface, which agreed with initial device design intentions. Condensation film thickness grew to 5microm over the time interval, while the bulk interface tracked from initial 12microm from the lid to 20microm from the lid. Surface tension effects dominating vapor pressure kept the liquid near the heat source; however, the temperature and pressure VLE data suggested vapor interface growth from the heated surface to 5microm above the heated copper plate. Reinforcing the simulation results, including location and movement of phase interfaces, was accomplished through a thorough ten dimensionless number analyses. These specialized ratios indicated dominant fluid and heat transfer behavior including phase change conditions. Thus, fabrication and empirical results for the heat energy harvesting prototype were successful and computational modeling provided understanding of applicable internal system behavior.

Downhole Transformation of the Hydraulic Fracturing Fluid Biocide Glutaraldehyde: Implications for Flowback and Produced Water Quality.

PubMed

Kahrilas, Genevieve A; Blotevogel, Jens; Corrin, Edward R; Borch, Thomas

2016-10-18

Hydraulic fracturing fluid (HFF) additives are used to enhance oil and gas extraction from unconventional shale formations. Several kilometers downhole, these organic chemicals are exposed to temperatures up to 200 °C, pressures above 10 MPa, high salinities, and a pH range from 5-8. Despite this, very little is known about the fate of HFF additives under these extreme conditions. Here, stainless steel reactors are used to simulate the downhole chemistry of the commonly used HFF biocide glutaraldehyde (GA). The results show that GA rapidly (t 1/2 < 1 h) autopolymerizes, forming water-soluble dimers and trimers, and eventually precipitates out at high temperatures (∼140 °C) and/or alkaline pH. Interestingly, salinity was found to significantly inhibit GA transformation. Pressure and shale did not affect GA transformation and/or removal from the bulk fluid. On the basis of experimental pseudo-second-order rate constants, a kinetic model for GA downhole half-life predictions for any combination of these conditions within the limits tested was developed. These findings illustrate that the biocidal GA monomer has limited time to control microbial activity in hot and/or alkaline shales, and may return along with its aqueous transformation products to the surface via flowback and produced water in cooler, more acidic, and saline shales.

Temperature and pressure correlation for volume of gas hydrates with crystal structures sI and sII

NASA Astrophysics Data System (ADS)

Vinš, Václav; Jäger, Andreas; Hielscher, Sebastian; Span, Roland; Hrubý, Jan; Breitkopf, Cornelia

The temperature and pressure correlations for the volume of gas hydrates forming crystal structures sI and sII developed in previous study [Fluid Phase Equilib. 427 (2016) 268-281], focused on the modeling of pure gas hydrates relevant in CCS (carbon capture and storage), were revised and modified for the modeling of mixed hydrates in this study. A universal reference state at temperature of 273.15 K and pressure of 1 Pa is used in the new correlation. Coefficients for the thermal expansion together with the reference lattice parameter were simultaneously correlated to both the temperature data and the pressure data for the lattice parameter. A two-stage Levenberg Marquardt algorithm was employed for the parameter optimization. The pressure dependence described in terms of the bulk modulus remained unchanged compared to the original study. A constant value for the bulk modulus B0 = 10 GPa was employed for all selected hydrate formers. The new correlation is in good agreement with the experimental data over wide temperature and pressure ranges from 0 K to 293 K and from 0 to 2000 MPa, respectively. Compared to the original correlation used for the modeling of pure gas hydrates the new correlation provides significantly better agreement with the experimental data for sI hydrates. The results of the new correlation are comparable to the results of the old correlation in case of sII hydrates. In addition, the new correlation is suitable for modeling of mixed hydrates.

Influence of mixing conditions on the rheological properties and structure of capillary suspensions

PubMed Central

Bossler, Frank; Weyrauch, Lydia; Schmidt, Robert; Koos, Erin

2017-01-01

The rheological properties of a suspension can be dramatically altered by adding a small amount of a secondary fluid that is immiscible with the bulk liquid. These capillary suspensions exist either in the pendular state where the secondary fluid preferentially wets the particles or the capillary state where the bulk fluid is preferentially wetting. The yield stress, as well as storage and loss moduli, depends on the size and distribution of secondary phase droplets created during sample preparation. Enhanced droplet breakup leads to stronger sample structures. In capillary state systems, this can be achieved by increasing the mixing speed and time of turbulent mixing using a dissolver stirrer. In the pendular state, increased mixing speed also leads to better droplet breakup, but spherical agglomeration is favored at longer times decreasing the yield stress. Additional mixing with a ball mill is shown to be beneficial to sample strength. The influence of viscosity variance between the bulk and second fluid on the droplet breakup is excluded by performing experiments with viscosity-matched fluids. These experiments show that the capillary state competes with the formation of Pickering emulsion droplets and is often more difficult to achieve than the pendular state. PMID:28194044

How Does Boiling in the Earth's Crust Influence Metal Speciation and Transport?

NASA Astrophysics Data System (ADS)

Kam, K.; Lemke, K.

2014-12-01

The presence of large quantities of precious metals, such as gold and copper, near the Earth's surface (upper crust) is commonly attributed to transport in aqueous solution and precipitation upon variations in temperature and pressure. As a consequence, gold exploration is closely linked to solution chemistry, i.e. hydrothermal processes involving aqueous fluids with densities of around unity. However, as crustal fluids buoyantly ascend, boiling produces a coexisting low-density aqueous liquid with fundamentally different physical and chemical properties, and a, most importantly, a high affinity for coinage metals (Heinrich et al., Econ Geol., 1992, 87, 1566). From recent experimental studies of Au (Hurtig and Williams-Jones, 2014, Geochim. Cosmochim. Acta,, 127, 304), we know that metal speciation in this low-density phase differs fundamentally from that observed in bulk solution, clearly, with important implications for Au, and metal speciation in general, transport and ore concentrations processes (these processes would also be operable in industrial geothermal plants given the quite special solvent properties of steam). In brief, this study focuses on the speciation of select metal halides in bulk solution as well as in water vapor, and is driven by our need to understand the solvent properties of around 2.0x109 cubic kilometers of free water (or 2,500 times as much water as stored in all lakes and rivers) present in the Earth's crust. The scope of this study has particular applications in the geothermal and oil industries, as both deal with high temperature low-density aqueous fluids. Understanding how metal halide species behave upon boiling can also provide insight into how metals, such as copper and silver, coat turbine equipment and steam piping in geothermal plants, ultimately rendering these components inoperable. This study will also provide preliminary results from mass spectrometric experiments of transition metal halides, and will be augmented with results from molecular simulations of metal halides that are aimed at characterizing the nature (i.e. relativistic structures and energies) of metal clusters in water vapor.

Direct Comparison of Surface and Bulk Relaxation of PS - A Temperature Dependent Study

NASA Astrophysics Data System (ADS)

Wu, Wen-Li; Sambasivan, Sharadha; Wang, Chia-Ying; Genzer, Jan; Fischer, Daniel A.

2005-03-01

Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy was used to measure simultaneously the relaxation rates of polystyrene (PS) molecules at the free surface and in the bulk. The samples were uniaxially oriented at room temperature via a modified cold rolling process. The density of the oriented samples as determined by liquid immersion technique is identical to that of bulk PS. At temperatures below its bulk glass transition temperature the rate of surface and bulk chain relaxation was monitored by measuring the partial-electron yield (PEY) and the fluorescence NEXAFS yields (FS), respectively, both parallel and perpendicular to the stretching direction. The decay rate of the dichroic ratios from both PEY and FY at various temperatures was taken as a measure of the relaxation rate of surface and bulk molecules respectively. In addition, the decay rate of the optical birefringence was also measured to provide an independent measure of the bulk relaxation. Relaxation of PS chains was found to occur faster on the surface relative to the bulk. The magnitude of the surface glass transition temperature suppression over the bulk was estimated to be 18 C based on the measured temperature dependence of the relaxation rates.

Molecular simulation of CO chemisorption on Co(0001) in presence of supercritical fluid solvent: A potential of mean force study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Asiaee, Alireza; Benjamin, Kenneth M., E-mail: kenneth.benjamin@sdsmt.edu

2016-08-28

For several decades, heterogeneous catalytic processes have been improved through utilizing supercritical fluids (SCFs) as solvents. While numerous experimental studies have been established across a range of chemistries, such as oxidation, pyrolysis, amination, and Fischer-Tropsch synthesis, still there is little fundamental, molecular-level information regarding the role of the SCF on elementary heterogeneous catalytic steps. In this study, the influence of hexane solvent on the adsorption of carbon monoxide on Co(0001), as the first step in the reaction mechanism of many processes involving syngas conversion, is probed. Simulations are performed at various bulk hexane densities, ranging from ideal gas conditions (nomore » SCF hexane) to various near- and super-critical hexane densities. For this purpose, both density functional theory and molecular dynamics simulations are employed to determine the adsorption energy and free energy change during CO chemisorption. Potential of mean force calculations, utilizing umbrella sampling and the weighted histogram analysis method, provide the first commentary on SCF solvent effects on the energetic aspects of the chemisorption process. Simulation results indicate an enhanced stability of CO adsorption on the catalyst surface in the presence of supercritical hexane within the reduced pressure range of 1.0–1.5 at a constant temperature of 523 K. Furthermore, it is shown that the maximum stability of CO in the adsorbed state as a function of supercritical hexane density at 523 K nearly coincides with the maximum isothermal compressibility of bulk hexane at this temperature.« less

The Boiling eXperiment Facility (BXF) for the Microgravity Science Glovebox (MSG)

NASA Technical Reports Server (NTRS)

McQuillen, John; Chao, David; Vergilii, Frank

2006-01-01

Boiling is an effective means of cooling by removing heat from surfaces through vaporization of a working fluid. It is also affected by both the magnitude and direction of gravity. By conducting pool boiling tests in microgravity, the effect of buoyancy n the overall boiling process and the relative magnitude of other phenomena can be assessed. The Boiling eXperiment Facility (BXF) is being built for the Microgravity Science Glovebox. This facility will conduct two pool boiling studies. The first study the Microheater Array Boiling Experiment (MABE) uses two 96 element microheater arrays, 2.7 mm and 7.0 mm in size, to measure localized hear fluxes while operating at a constant temperature. The other experiment, the Nucleate Pool Boiling eXperiment (NPBX) uses a 85 mm diameter heater wafer that has been "seeded" with five individually-controlled nucleation sites to study bubble nucleation, growth, coalescence and departure. The BXF uses normal-perfluorohexane as the test fluid and will operate between pressures of 60 to 244 Pa. and temperatures of 35 to 60 C. Both sets of experimental heaters are highly instrumented. Pressure and bulk fluid temperature measurements will be made with standard rate video. A high speed video system will be used to visualize the boiling process through the bottom of the MABE heater arrays. The BXF is currently scheduled to fly on Utilization Flight-13A.1 to the ISS with facility integration into the MSG and operation during Increment 15

Fluid inclusion studies of ejected nodules from plinian eruptions of Mt. Somma-Vesuvius

USGS Publications Warehouse

Belkin, H.E.; de Vivo, B.

1993-01-01

Mt. Somma-Vesuvius (Naples, Italy) has erupted potassium-rich and silica-undersaturated products during a complicated history of plinian and non-plinian events. Coarse-grained cognate nodules are commonly found in the pyroclastics and are upper crustal in origin. We examined cumulate and subeffusive nodules from the 3800 y.B.P. Avellino. A.D. 79 Pompei, and A.D. 472 Pollena eruptions. Silicate-melt and liquid-vapor fluid inclusion studies in clinopyroxene from both types of nodules have been used to assess the fluids attending crystallization and to place constraints on the pressure and temperature of nodule formation. Thermometric and volumetric data from primary and pseudosecondary CO2-H2O and CO2 and coeval silicate-melt fluid inclusions indicate that they were trapped at a pressure of ???1 to ???2.5 kbar at ???1200??C. This suggests a crystallization depth of ???4 to ???10 km. The H2O-bearing fluid inclusions are abundant from plinian eruptions in contrast to non-plinian eruptions where H2O-bearing fluid inclusions were rare. The presence of primary H2O-CO2 fluid inclusions indicates that an immiscible, supercritical H2O-CO2 fluid was in the nodule-forming environment. The H2O-bearing fluid inclusions in plinian nodules may record a higher pre-eruptive H2O content in the bulk magma that is dramatically reflected in the eruption dynamics. ?? 1993.

Bulk and Thin film Properties of Nanoparticle-based Ionic Materials

NASA Astrophysics Data System (ADS)

Fang, Jason

2008-03-01

Nanoparticle-based ionic materials (NIMS) offer exciting opportunities for research at the forefront of science and engineering. NIMS are hybrid particles comprised of a charged oligomeric corona attached to hard, inorganic nanoparticle cores. Because of their hybrid nature, physical properties --rheological, optical, electrical, thermal - of NIMS can be tailored over an unusually wide range by varying geometric and chemical characteristics of the core and canopy and thermodynamic variables such as temperature and volume fraction. On one end of the spectrum are materials with a high core content, which display properties similar to crystalline solids, stiff waxes, and gels. At the opposite extreme are systems that spontaneously form particle-based fluids characterized by transport properties remarkably similar to simple liquids. In this poster I will present our efforts to synthesize NIMS and discuss their bulk and surface properties. In particular I will discuss our work on preparing smart surfaces using NIMS.

A fundamental study of nucleate pool boiling under microgravity

NASA Technical Reports Server (NTRS)

Ervin, Jamie S.; Merte, Herman, Jr.

1991-01-01

An experimental study of incipient boiling in short-term microgravity and with a/g = +/- 1 for pool boiling was performed. Calibrated thin gold films sputtered on a smoothly polished quartz surface were used simultaneously for thermal resistance measurements and heating of the boiling surface. The gold films were used for both transient and quasi-steady heating surface temperature measurements. Two test vessels were constructed for precise measurement and control of fluid temperature and pressure: a laboratory pool boiling vessel for the a/g = +/- experiments and a pool boiling vessel designed for the 131 m free-fall in the NASA Lewis Research Center Microgravity Research Facility for the microgravity tests. Measurements included the heater surface temperature, the pressure near the heating surface, and the bulk liquid temperatures. High speed photography was used in the experiments. With high quality microgravity and the measured initial temperature of the quiescent test fluid, R113, the temperature distribution in the liquid at the moment of boiling inception resulting from an imposed step in heat flux is known with a certainty not possible previously. The types of boiling propagation across the large flat heating surface are categorized; the conditions necessary for their occurrence are described. Explosive boiling propagation with a striking pattern of small scale protuberances over the entire vapor mass periphery not observed previously at low heat flux levels is described. For the heater surface with a/g = -1, a step in the heater surface temperature of short duration was imposed. The resulting liquid temperature distribution at the moment of boiling inception was different from that obtained with a step in heat flux.

Plasma properties of driver gas following interplanetary shocks observed by ISEE-3

NASA Technical Reports Server (NTRS)

Zwickl, R. D.; Asbridge, J. R.; Bame, S. J.; Feldman, W. C.; Gosling, J. T.; Smith, E. J.

1983-01-01

Plasma fluid parameters calculated from solar wind and magnetic field data to determine the characteristic properties of driver gas following a select subset of interplanetary shocks were studied. Of 54 shocks observed from August 1978 to February 1980, 9 contained a well defined driver gas that was clearly identifiable by a discontinuous decrease in the average proton temperature. While helium enhancements were present downstream of the shock in all 9 of these events, only about half of them contained simultaneous changes in the two quantities. Simultaneous with the drop in proton temperature the helium and electron temperature decreased abruptly. In some cases the proton temperature depression was accompanied by a moderate increase in magnetic field magnitude with an unusually low variance, by a small decrease in the variance of the bulk velocity, and by an increase in the ratio of parallel to perpendicular temperature. The cold driver gas usually displayed a bidirectional flow of suprathermal solar wind electrons at higher energies.

Electrical conductivity of H2O-NaCl fluids to 10 kbar

NASA Astrophysics Data System (ADS)

Sinmyo, R.; Keppler, H.

2016-12-01

Magnetotelluric studies often reveal zones of elevated electrical conductivity in the mantle wedge above subducting slabs, in the deep crust below fold belts, or below active volcanoes. Since both aqueous fluids and hydrous silivate melts may be highly conductive, they may both account for these observations. Distinguishing between these two posssibilities, however, is difficult. One reason for this problem is that while there are very good conductivity data for silicate melts, such data do not exist for aqueous fluids under the relevant conditions of pressure, temperature and solute concentration. Most crustal and mantle fluids likely contain some NaCl, which greatly enhances conductivity due to its partial dissociation into Na+ and Cl-. We therefore studied the electrical conductivity of 0.01, 0.1 and 1 m NaCl solutions in water to 10 kbar and 600 °C. The measurements were carried out in externally-heated diamond cells containing two gaskets separated by an insulating ring of diamond, following a method described by Ni et al. (2014). The two gaskets were used as electrodes and full impedance spectra were measured from 30 Hz to 10 MHz using a Solartron 1260 impedance analyzer. Electrical conductivity was generally found to increase with pressure temperature, and fluid density. The conductivity increase observed upon variation of NaCl concentration from 0.1m to 1m was smaller than from 0.01m to 0.1m, which reflects the reduced degree of dissociation at high NaCl concentration. In general, the data show that already a very small fraction of NaCl-bearing aqueous fluid is sufficient to enhance bulk conductivities to values that would be expected for a high degree of partial melting. Accordingly, aqueous fluids may be distinguished from hydrous melts by comparing magnetotelluric and seismic data. H2O-NaCl fluids may enhance electrical conductivities with little disturbance of vp or vp/vs ratios.

Direct observation of cerebrospinal fluid bulk flow in the brain

NASA Astrophysics Data System (ADS)

Mestre, Humberto; Tithof, Jeffrey; Thomas, John; Kelley, Douglas; Nedergaard, Maiken

2017-11-01

Cerebrospinal fluid (CSF) serves a vital role in normal brain function. Its adequate flow and exchange with interstitial fluid through perivascular spaces (PVS) has been shown to be important in the clearance of toxic metabolites like amyloid- β, and its disturbance can cause severe neurological diseases. It has long been suspected that bulk flow may transport CSF, but limitations in imaging techniques have prevented direct observation of such flows in the PVS. In this talk, we describe a novel approach using high speed two photon laser scanning microscopy which has allowed for the first ever direct observation of CSF flow in the PVS of a mouse brain. By performing particle tracking velocimetry, we quantify the CSF bulk flow speeds and PVS geometry. This technique enables future studies of CSF flow disturbances on a new scale and will pave the way for evaluating the role of these fluxes in neurodegenerative disease. R01NS100366 (to M.N.).

The Iceland Deep Drilling Project (IDDP): Deep Fluid Sampling in Fractured Quartz, Reykjanes Geothermal System, Iceland

NASA Astrophysics Data System (ADS)

Seward, R. J.; Reed, M. H.; Grist, H. R.; Fridriksson, T.; Danielsen, P.; Thorhallsson, S.; Elders, W. A.; Fridleifsson, G. O.

2011-12-01

In July of 2011 a fluid inclusion tool (FIT) was deployed in well RN-17b of the Reykjanes geothermal system, Iceland, with the goal of sampling fluids in situ at the deepest feed point in the well. The tool consists of a perforated stainless steel pipe containing eight stainless steel mesh canisters, each loaded with 10mm-scale blocks of thermally fractured quartz. Except for one control canister, in each canister the fractured quartz blocks were surrounded by a different grain size of SiO¬2 glass that ranged in size from 10μm-scale glass wool to cm-scale glass shards. The FIT was left in the well on a wireline at a depth of 2768m and retrieved after three weeks. The fluid at 2768m depth is known from November 2010 well logs to have a temperature of about 330°C and pressure of 170 bars, a pressure ~40 bar too high for boiling at that temperature. After retrieval, quartz in all of the canisters contained liquid-dominated fluid inclusions, but their quantity and size differed by canister. Groups of inclusions occur in healed fractures and both healed and open fracture surfaces are visible within single quartz blocks. Measurements on a heating and cooling stage yield approximant inclusion homogenization temperatures of 332°C and freezing points of -2.0°C. These measurements and a pressure of 170 bars yield trapping temperatures of 335°C and a NaCl weight percent of 3.4, both of which match known values, thus verifying that the device trapped fluids as intended. In upcoming studies, these fluids will be analyzed using bulk methods and LA-ICP-MS on individual inclusions. The glass added to the quartz blocks in the canisters allowed the Reykjanes fluids to precipitate enough quartz to heal fractures and trap fluids despite the fluid undersaturation in quartz. Almost all of the glass that was added to the canisters, 27 to 66 grams in each (except glass wool), was consumed in the experiment. Remaining glass was in the non-mesh bottom caps of the canisters where fluid flux may have been minimal, indicating that most of the dissolved SiO2 was carried away with flowing fluid. This may explain why not all fractures were healed, as they were in our previous closed-system laboratory experiments. Upon recovery from the well, the FIT and the canister contents were covered in fine black particles, the greatest quantity by far occurring in canisters that had contained glass wool as the SiO2 source. Preliminary SEM-EDS analyses show that the particles contain silica, iron, magnesium, and small amounts of zinc sulfide. The precipitation of sulfides from the fluid sampled in the quartz fractures provides a valuable constraint on interpretation of the fluid inclusion compositions.

Fluid-rock Interactions recorded in Serpentinites subducted to 60-80 km Depth

NASA Astrophysics Data System (ADS)

Peters, D.; John, T.; Scambelluri, M.; Pettke, D. T.

2016-12-01

The HP metamorphic serpentinised peridotites of Erro-Tobbio (ET, Italy) offer a unique possibility to study fluid-rock interactions in subducted ultrabasic rocks that reached 550-650°C at 2-2.5 GPa. They contain metamorphic olivine + Ti-clinohumite in both the serpentinite matrix and veins cutting the rock foliation, interpreted to represent partial serpentinite dehydration fluid pathways [1,2] being variably retrogressed as e.g., indicated by chrysotile/lizardite mesh textures in vein olivine in strongly altered samples. This study aims to constraining the origin of fluid(s) and the scale(s) of fluid-rock interaction based on major to trace element systematics employing detailed bulk rock (nanoparticulate pressed powder pellet LA-ICP-MS [3] and ion chromatography / liquid ICP-MS analysis), and in situ mineral analysis (work in progress). Bulk data show moderate fluid-mobile element (FME) enrichment for Cs, Rb, Ba, Pb, As, and Sb (up to 100 times primitive mantle (PM)), W (1000 PM), and B (10000 PM). Alkali over U ratios of compiled serpentinite data (n ˜ 620) reveal distinctive global FME enrichment trends for MOR vs. forearc (FA) serpentinisation. ET serpentinites fall into the latter, indicating both sediment-equilibrated fluids and the preservation of characteristic FME enrichment patterns in HP serpentinites. Petrography reveals a multiphase evolution of the HP veins including retrograde serpentinisation, whereas serpentinite hosts have remained largely unaffected by retrogression. Comparison of vein vs. wall rock bulk data indicate vein-forming fluids in equilibrium with wall rocks, however, without evidence for external fluid ingress. The preservation of multiple fluid-rock interaction episodes and the lack of external fluid ingress in the ET HP serpentinites indicate near-closed system behaviour throughout subduction and imprint of characteristic fluid signatures onto the mantle. [1] Scambelluri et al. (1995) Geology, 23, 459-462. [2] John et al. (2011) Earth Planet Sci Lett 308, 65-76. [3] Peters and Pettke (2016) GGR, DOI: 10.1111/ggr.12125.

Effect of Mantle Wedge Hybridization by Sediment Melt on Geochemistry of Arc Magma and Arc Mantle Source - Insights from Laboratory Experiments at High Pressures and Temperatures

NASA Astrophysics Data System (ADS)

Mallik, A.; Dasgupta, R.; Tsuno, K.; Nelson, J. M.

2015-12-01

Generation of arc magmas involves metasomatism of the mantle wedge by slab-derived H2O-rich fluids and/or melts and subsequent melting of the modified source. The chemistry of arc magmas and the residual mantle wedge are not only regulated by the chemistry of the slab input, but also by the phase relations of metasomatism or hybridization process in the wedge. The sediment-derived silica-rich fluids and hydrous partial melts create orthopyroxene-rich zones in the mantle wedge, due to reaction of mantle olivine with silica in the fluid/melt [1,2]. Geochemical evidence for such a reaction comes from pyroxenitic lithologies coexisting with peridotite in supra-subduction zones. In this study, we have simulated the partial melting of a parcel of mantle wedge modified by bulk addition of sediment-derived melt with variable H2O contents to investigate the major and trace element chemistry of the magmas and the residues formed by this process. Experiments at 2-3 GPa and 1150-1300 °C were conducted on mixtures of 25% sediment-derived melt and 75% lherzolite, with bulk H2O contents varying from 2 to 6 wt.%. Partial reactive crystallization of the rhyolitic slab-derived melt and partial melting of the mixed source produced a range of melt compositions from ultra-K basanites to basaltic andesites, in equilibrium with an orthopyroxene ± phlogopite ± clinopyroxene ± garnet bearing residue, depending on P and bulk H2O content. Model calculations using partition coefficients (from literature) of trace elements between experimental minerals and silicate melt suggest that the geochemical signatures of the slab-derived melt, such as low Ce/Pb and depletion in Nb and Ta (characteristic slab signatures) are not erased from the resulting melt owing to reactive crystallization. The residual mineral assemblage is also found to be similar to the supra-subduction zone lithologies, such as those found in Dabie Shan (China) and Sanbagawa Belt (Japan). In this presentation, we will also compare the major and trace element characteristics of bulk rock and minerals found in orthopyroxenites from supra-subduction zones with the residua formed in our experiments, to differentiate between melt versus fluid, and sediment- versus basalt-derived flux in the mantle wedge. [1] Mallik et al. (2015) CMP169(5) [2] Sekine & Wyllie (1982) CMP 81(3)

A binomial modeling approach for upscaling colloid transport under unfavorable conditions: Emergent prediction of extended tailing

NASA Astrophysics Data System (ADS)

Hilpert, Markus; Rasmuson, Anna; Johnson, William P.

2017-07-01

Colloid transport in saturated porous media is significantly influenced by colloidal interactions with grain surfaces. Near-surface fluid domain colloids experience relatively low fluid drag and relatively strong colloidal forces that slow their downgradient translation relative to colloids in bulk fluid. Near-surface fluid domain colloids may reenter into the bulk fluid via diffusion (nanoparticles) or expulsion at rear flow stagnation zones, they may immobilize (attach) via primary minimum interactions, or they may move along a grain-to-grain contact to the near-surface fluid domain of an adjacent grain. We introduce a simple model that accounts for all possible permutations of mass transfer within a dual pore and grain network. The primary phenomena thereby represented in the model are mass transfer of colloids between the bulk and near-surface fluid domains and immobilization. Colloid movement is described by a Markov chain, i.e., a sequence of trials in a 1-D network of unit cells, which contain a pore and a grain. Using combinatorial analysis, which utilizes the binomial coefficient, we derive the residence time distribution, i.e., an inventory of the discrete colloid travel times through the network and of their probabilities to occur. To parameterize the network model, we performed mechanistic pore-scale simulations in a single unit cell that determined the likelihoods and timescales associated with the above colloid mass transfer processes. We found that intergrain transport of colloids in the near-surface fluid domain can cause extended tailing, which has traditionally been attributed to hydrodynamic dispersion emanating from flow tortuosity of solute trajectories.

Bulk-Flow Analysis, part A

NASA Technical Reports Server (NTRS)

Childs, Dara W.

1993-01-01

The bulk-flow analysis results for this contract are incorporated in the following publications: 'Fluid-Structure Interaction Forces at Pump-Impeller Shroud Surfaces for Axial Vibration Analysis'; 'Centrifugal Acceleration Modes for Incompressible Fluid in the Leakage Annulus Between a Shrouded Pump Impeller and Its Housing'; 'Influence of Impeller Shroud Forces on Pump Rotordynamics'; 'Pressure Oscillation in the Leakage Annulus Between a Shrouded Impeller and Its Housing Due to Impeller-Discharge-Pressure Disturbances'; and 'Compressibility Effects on Rotor Forces in the Leakage Path Between a Shrouded Pump Impeller and Its Housing'. These publications are summarized and included in this final report. Computational Fluid Mechanics (CFD) results developed by Dr. Erian Baskharone are reported separately.

Cryogenic Autogenous Pressurization Testing for Robotic Refueling Mission 3

NASA Technical Reports Server (NTRS)

Boyle, R.; DiPirro, M.; Tuttle, J.; Francis, J.; Mustafi, S.; Li, X.; Barfknecht, P.; DeLee, C. H.; McGuire, J.

2015-01-01

A wick-heater system has been selected for use to pressurize the Source Dewar of the Robotic Refueling Mission Phase 3 on-orbit cryogen transfer experiment payload for the International Space Station. Experimental results of autogenous pressurization of liquid argon and liquid nitrogen using a prototype wick-heater system are presented. The wick-heater generates gas to increase the pressure in the tank while maintaining a low bulk fluid temperature. Pressurization experiments were performed in 2013 to characterize the performance of the wick heater. This paper describes the experimental setup, pressurization results, and analytical model correlations.

Impact of temperature-velocity distribution on fusion neutron peak shape

DOE PAGES

Munro, D. H.; Field, J. E.; Hatarik, R.; ...

2017-02-21

Doppler broadening of the 14 MeV DT and 2.45 MeV DD fusion neutron lines has long been our best measure of temperature in a burning plasma. At the National Ignition Facility (NIF), yields are high enough and our neutron spectrometers accurate enough that we see finer details of the peak shape. For example, we can measure the shift of the peak due to the bulk motion of the plasma, and we see indications of non-thermal broadening, skew, and kurtosis of the peak caused by the variations of temperature and fluid velocity during burn. We can also distinguish spectral differences amongmore » several lines of sight. Finally, this paper will review the theory of fusion neutron line shape, show examples of non-Gaussian line shapes and directional variations in NIF data, and describe detailed spectral shapes we see in radiation-hydrodynamics simulations of implosions.« less

Impact of temperature-velocity distribution on fusion neutron peak shape

NASA Astrophysics Data System (ADS)

Munro, D. H.; Field, J. E.; Hatarik, R.; Peterson, J. L.; Hartouni, E. P.; Spears, B. K.; Kilkenny, J. D.

2017-05-01

Doppler broadening of the 14 MeV DT and 2.45 MeV DD fusion neutron lines has long been our best measure of temperature in a burning plasma. At the National Ignition Facility (NIF), yields are high enough and our neutron spectrometers accurate enough that we see finer details of the peak shape. For example, we can measure the shift of the peak due to the bulk motion of the plasma, and we see indications of non-thermal broadening, skew, and kurtosis of the peak caused by the variations of temperature and fluid velocity during burn. We can also distinguish spectral differences among several lines of sight. This paper will review the theory of fusion neutron line shape, show examples of non-Gaussian line shapes and directional variations in NIF data, and describe detailed spectral shapes we see in radiation-hydrodynamics simulations of implosions.

Black hole acoustics in the minimal geometric deformation of a de Laval nozzle

NASA Astrophysics Data System (ADS)

da Rocha, Roldão

2017-05-01

The correspondence between sound waves, in a de Laval propelling nozzle, and quasinormal modes emitted by brane-world black holes deformed by a 5D bulk Weyl fluid are here explored and scrutinized. The analysis of sound waves patterns in a de Laval nozzle in the laboratory, reciprocally, is here shown to provide relevant data about the 5D bulk Weyl fluid and its on-brane projection, comprised by the minimal geometrically deformed compact stellar distribution on the brane. Acoustic perturbations of the gas fluid flow in the de Laval nozzle are proved to coincide with the quasinormal modes of black holes solutions deformed by the 5D Weyl fluid, in the geometric deformation procedure. Hence, in a phenomenological Eötvös-Friedmann fluid brane-world model, the realistic shape of a de Laval nozzle is derived and its consequences studied.

Natural convection along a heated vertical plate immersed in a nonlinearly stratified medium: application to liquefied gas storage

NASA Astrophysics Data System (ADS)

Forestier, M.; Haldenwang, P.

We consider free convection driven by a heated vertical plate immersed in a nonlinearly stratified medium. The plate supplies a uniform horizontal heat flux to a fluid, the bulk of which has a stable stratification, characterized by a non-uniform vertical temperature gradient. This gradient is assumed to have a typical length scale of variation, denoted Z0, while 0, and the physical properties of the medium.We then apply the new theory to the natural convection affecting the vapour phase in a liquefied pure gas tank (e.g. the cryogenic storage of hydrogen). It is assumed that the cylindrical storage tank is subject to a constant uniform heat flux on its lateral and top walls. We are interested in the vapour motion above a residual layer of liquid in equilibrium with the vapour. High-precision axisymmetric numerical computations show that the flow remains steady for a large range of parameters, and that a bulk stratification characterized by a quadratic temperature profile is undoubtedly present. The application of the theory permits a comparison of the numerical and analytic results, showing that the theory satisfactorily predicts the primary dynamical and thermal properties of the storage tank.

Hydrodynamic cavitation to improve bulk fluid to surface mass transfer in a nonimmersed ultraviolet system for minimal processing of opaque and transparent fluid foods.

PubMed

Milly, P J; Toledo, R T; Chen, J; Kazem, B

2007-11-01

Ultraviolet (UV)-induced chemical reactions and inactivation of microorganisms in transparent and opaque fluids are strongly dependent upon the homogenous exposure of the target species to the UV irradiation. Current UV technologies used in water disinfection and food preservation applications have limited efficacy due to suspended particles shading target species. An Ultraviolet-Shockwave Power Reactor (UV-SPR) consisting of an inner rotating rotor and a stationary quartz housing and 2 end plates was used to induce 'controlled cavitation.' Eight UV low-pressure mercury lamps spaced uniformly were installed lengthwise around the quartz housing periphery. A KI to I(3) (-)chemical dosimeter for UV was used to quantify photons received by fluid in the annular space of the SPR. UV dose (J/m(2)) increased from 97 J/m(2) at 0 rpm to over 700 J/m(2) for SPR speeds above 2400 rpm. Inactivation of E. coli 25922 in apple juice and skim milk in the UV-SPR at exit temperatures below 45 degrees C was greater than 4.5 and 3 logs, respectively. The UV-SPR system proved successful in increasing the mass transfer of transparent and opaque fluid to the UV irradiated surface.

High-pressure cell for neutron reflectometry of supercritical and subcritical fluids at solid interfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carmichael, Justin R; Rother, Gernot; Browning, Jim

2012-01-01

A new high-pressure cell design for use in neutron reflectometry (NR) for pressures up to 50 MPa and a temperature range of 300 473 K is described. The cell design guides the neutron beam through the working crystal without passing through additional windows or the bulk fluid, which provides for a high neutron transmission, low scattering background, and low beam distortion. The o-ring seal is suitable for a wide range of subcritical and supercritical fluids and ensures high chemical and pressure stability. Wafers with a diameter of 5.08 cm (2 in.) and 5 mm or 10 mm thickness can bemore » used with the cells, depending on the required pressure and momentum transfer range. The fluid volume in the sample cell is very small at about 0.1 ml, which minimizes scattering background and stored energy. The cell design and pressure setup for measurements with supercritical fluids are described. NR data are shown for silicon/silicon oxide and quartz wafers measured against air and subsequently within the high-pressure cell to demonstrate the neutron characteristics of the high-pressure cell. Neutron reflectivity data for supercritical CO2 in contact with quartz and Si/SiO2 wafers are also shown.« less

Tuning the tetrahedrality of the hydrogen-bonded network of water: Comparison of the effects of pressure and added salts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prasad, Saurav, E-mail: saurav7188@gmail.com, E-mail: cyz118212@chemistry.iitd.ac.in; Chakravarty, Charusita

Experiments and simulations demonstrate some intriguing equivalences in the effect of pressure and electrolytes on the hydrogen-bonded network of water. Here, we examine the extent and nature of equivalence effects between pressure and salt concentration using relationships between structure, entropy, and transport properties based on two key ideas: first, the approximation of the excess entropy of the fluid by the contribution due to the atom-atom pair correlation functions and second, Rosenfeld-type excess entropy scaling relations for transport properties. We perform molecular dynamics simulations of LiCl–H{sub 2}O and bulk SPC/E water spanning the concentration range 0.025–0.300 molefraction of LiCl at 1more » atm and pressure range from 0 to 7 GPa, respectively. The temperature range considered was from 225 to 350 K for both the systems. To establish that the time-temperature-transformation behaviour of electrolyte solutions and water is equivalent, we use the additional observation based on our simulations that the pair entropy behaves as a near-linear function of pressure in bulk water and of composition in LiCl–H{sub 2}O. This allows for the alignment of pair entropy isotherms and allows for a simple mapping of pressure onto composition. Rosenfeld-scaling implies that pair entropy is semiquantitatively related to the transport properties. At a given temperature, equivalent state points in bulk H{sub 2}O and LiCl–H{sub 2}O (at 1 atm) are defined as those for which the pair entropy, diffusivity, and viscosity are nearly identical. The microscopic basis for this equivalence lies in the ability of both pressure and ions to convert the liquid phase into a pair-dominated fluid, as demonstrated by the O–O–O angular distribution within the first coordination shell of a water molecule. There are, however, sharp differences in local order and mechanisms for the breakdown of tetrahedral order by pressure and electrolytes. Increasing pressure increases orientational disorder within the first neighbour shell while addition of ions shifts local orientational order from tetrahedral to close-packed as water molecules get incorporated in ionic hydration shells. The variations in local order within the first hydration shell may underlie ion-specific effects, such as the Hofmeister series.« less

Tuning the tetrahedrality of the hydrogen-bonded network of water: Comparison of the effects of pressure and added salts

NASA Astrophysics Data System (ADS)

Prasad, Saurav; Chakravarty, Charusita

2016-06-01

Experiments and simulations demonstrate some intriguing equivalences in the effect of pressure and electrolytes on the hydrogen-bonded network of water. Here, we examine the extent and nature of equivalence effects between pressure and salt concentration using relationships between structure, entropy, and transport properties based on two key ideas: first, the approximation of the excess entropy of the fluid by the contribution due to the atom-atom pair correlation functions and second, Rosenfeld-type excess entropy scaling relations for transport properties. We perform molecular dynamics simulations of LiCl-H2O and bulk SPC/E water spanning the concentration range 0.025-0.300 molefraction of LiCl at 1 atm and pressure range from 0 to 7 GPa, respectively. The temperature range considered was from 225 to 350 K for both the systems. To establish that the time-temperature-transformation behaviour of electrolyte solutions and water is equivalent, we use the additional observation based on our simulations that the pair entropy behaves as a near-linear function of pressure in bulk water and of composition in LiCl-H2O. This allows for the alignment of pair entropy isotherms and allows for a simple mapping of pressure onto composition. Rosenfeld-scaling implies that pair entropy is semiquantitatively related to the transport properties. At a given temperature, equivalent state points in bulk H2O and LiCl-H2O (at 1 atm) are defined as those for which the pair entropy, diffusivity, and viscosity are nearly identical. The microscopic basis for this equivalence lies in the ability of both pressure and ions to convert the liquid phase into a pair-dominated fluid, as demonstrated by the O-O-O angular distribution within the first coordination shell of a water molecule. There are, however, sharp differences in local order and mechanisms for the breakdown of tetrahedral order by pressure and electrolytes. Increasing pressure increases orientational disorder within the first neighbour shell while addition of ions shifts local orientational order from tetrahedral to close-packed as water molecules get incorporated in ionic hydration shells. The variations in local order within the first hydration shell may underlie ion-specific effects, such as the Hofmeister series.

Global asymmetry of fluids and local singularity in the diameter of the coexistence curve.

PubMed

Rogankov, Vitaly B; Levchenko, Valeriy I

2013-05-01

By combining a measurable vapor-liquid coexistence curve and the extended van der Waals-type of equation of state (EOS) with the additional temperature-dependent coefficient, the phenomenological model of global fluid asymmetry has been developed separately for both coexisting bulk phases in the entire range of subcritical states. It is shown, in particular, that the adequate description of a liquid branch and its near-critical vicinity in terms of appropriate critical exponents and amplitudes connected by the two-scale-factor universal interrelations can be achieved. The asymmetric influence of heterophase fluctuations on the criticality of gaseous states is demonstrated. It is inherently similar to the well-known Fisher's droplet model, which corresponds to the scaling EOS too. The principle of corresponding isotherms has been formulated without any adjustable parameters. An attempt to avoid the use of a locally singular coexistence-curve diameter is proposed in the framework of two alternative models. The accurate vapor-liquid data for two fluid metals, Rb and Cs, as well as two molecular fluids, C(2)H(6) and CO(2), are reanalyzed by the above models to confirm the presumed opportunity.

Fluid-structural dynamics of ground-based and microgravity caloric tests

NASA Technical Reports Server (NTRS)

Kassemi, M.; Oas, J. G.; Deserranno, Dimitri

2005-01-01

Microgravity caloric tests aboard the 1983 SpaceLab1 mission produced nystagmus results with an intensity comparable to those elicited during post- and pre- flight tests, thus contradicting the basic premise of Barany's convection hypothesis for caloric stimulation. In this work, we present a dynamic fluid structural analysis of the caloric stimulation of the lateral semicircular canal based on two simultaneous driving forces for the endolymphatic flow: natural convection driven by the temperature-dependent density variation in the bulk fluid and expansive convection caused by direct volumetric displacement of the endolymph during the thermal irrigation. Direct numerical simulations indicate that on earth, the natural convection mechanism is dominant. But in the microgravity environment of orbiting spacecraft, where buoyancy effects are mitigated, expansive convection becomes the sole mechanism for producing cupular displacement. A series of transient 1 g and microgravity case studies are presented to delineate the differences between the dynamics of the 1 g and microgravity endolymphatic flows. The impact of these different flow dynamics on the endolymph-cupula fluid-structural interactions is also analyzed based on the time evolutions of cupular displacement and velocity and the transcupular pressure differences.

Fluid-structural dynamics of ground-based and microgravity caloric tests.

PubMed

Kassemi, M; Oas, J G; Deserranno, Dimitri

2005-01-01

Microgravity caloric tests aboard the 1983 SpaceLab1 mission produced nystagmus results with an intensity comparable to those elicited during post- and pre- flight tests, thus contradicting the basic premise of Barany's convection hypothesis for caloric stimulation. In this work, we present a dynamic fluid structural analysis of the caloric stimulation of the lateral semicircular canal based on two simultaneous driving forces for the endolymphatic flow: natural convection driven by the temperature-dependent density variation in the bulk fluid and expansive convection caused by direct volumetric displacement of the endolymph during the thermal irrigation. Direct numerical simulations indicate that on earth, the natural convection mechanism is dominant. But in the microgravity environment of orbiting spacecraft, where buoyancy effects are mitigated, expansive convection becomes the sole mechanism for producing cupular displacement. A series of transient 1 g and microgravity case studies are presented to delineate the differences between the dynamics of the 1 g and microgravity endolymphatic flows. The impact of these different flow dynamics on the endolymph-cupula fluid-structural interactions is also analyzed based on the time evolutions of cupular displacement and velocity and the transcupular pressure differences.

Scaled particle theory for bulk and confined fluids: A review

NASA Astrophysics Data System (ADS)

Dong, Wei; Chen, XiaoSong

2018-07-01

More than half a century after its first formulation by Reiss, Frisch and Lebowitz in 1959, scaled particle theory (SPT) has proven its immense usefulness and has become one of the most successful theories in liquid physics. In recent years, we have strived to extend SPT to fluids confined in a variety of random porous matrices. In this article, we present a timely review of these developments. We have endeavored to present a formulation that is pedagogically more accessible than those presented in various original papers, and we hope this benefits newcomers in their research work. We also use more consistent notations for different cases. In addition, we discuss issues that have been scarcely considered in the literature, e.g., the one-fluid structure of SPT due to the isomorphism between the equation of state for a multicomponent fluid and that for a one-component fluid or the pure-confinement scaling relation that provides a connection between a confined and a bulk fluid.

Relativistic thermal electron scale instabilities in sheared flow plasma

NASA Astrophysics Data System (ADS)

Miller, Evan D.; Rogers, Barrett N.

2016-04-01

> The linear dispersion relation obeyed by finite-temperature, non-magnetized, relativistic two-fluid plasmas is presented, in the special case of a discontinuous bulk velocity profile and parallel wave vectors. It is found that such flows become universally unstable at the collisionless electron skin-depth scale. Further analyses are performed in the limits of either free-streaming ions or ultra-hot plasmas. In these limits, the system is highly unstable in the parameter regimes associated with either the electron scale Kelvin-Helmholtz instability (ESKHI) or the relativistic electron scale sheared flow instability (RESI) recently highlighted by Gruzinov. Coupling between these modes provides further instability throughout the remaining parameter space, provided both shear flow and temperature are finite. An explicit parameter space bound on the highly unstable region is found.

Elution of monomer from different bulk fill dental composite resins.

PubMed

Cebe, Mehmet Ata; Cebe, Fatma; Cengiz, Mehmet Fatih; Cetin, Ali Rıza; Arpag, Osman Fatih; Ozturk, Bora

2015-07-01

The purpose of this study was to evaluate the elution of Bis-GMA, TEGDMA, HEMA, and Bis-EMA monomers from six bulk fill composite resins over four different time periods, using HPLC. Six different composite resin materials were used in the present study: Tetric Evo Ceram Bulk Fill (Ivoclar Vivadent, Amherst, NY), X-tra Fill (VOCO, Cuxhaven, Germany), Sonic Fill (Kerr, Orange, CA, USA), Filtek Bulk Fill (3M ESPE Dental Product, St. Paul, MN), SDR (Dentsply, Konstanz, Germany), EQUIA (GC America INC, Alsip, IL). The samples (4mm thickness, 5mm diameter) were prepared and polymerized for 20s with a light emitted diode unit. After fabrication, each sample was immediately immersed in 75wt% ethanol/water solution used as extraction fluid and stored in the amber colored bottles at room temperature. Ethanol/water samples were taken (0.5mL) at predefined time intervals:10m (T1), 1h (T2), 24h (T3) and 30 days (T4). These samples were analyzed by HPLC. The obtained data were analyzed with one-way ANOVA and Tukey HSD at significance level of p<0.05. Amount of eluted Bis-EMA and Bis-GMA from Tetric Evo Ceram Bulk Fill and amount of eluted TEGDMA and HEMA from X-tra Fill higher than others composites (p<0.05). Residual monomers were eluted from bulk fill composite resins in all time periods and the amount of eluted monomers was increased with time. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

The influence of topology on hydraulic conductivity in a sand-and-gravel aquifer

USGS Publications Warehouse

Morin, Roger H.; LeBlanc, Denis R.; Troutman, Brent M.

2010-01-01

A field experiment consisting of geophysical logging and tracer testing was conducted in a single well that penetrated a sand-and-gravel aquifer at the U.S. Geological Survey Toxic Substances Hydrology research site on Cape Cod, Massachusetts. Geophysical logs and flowmeter/pumping measurements were obtained to estimate vertical profiles of porosity ϕ, hydraulic conductivity K, temperature, and bulk electrical conductivity under background, freshwater conditions. Saline-tracer fluid was then injected into the well for 2 h and its radial migration into the surrounding deposits was monitored by recording an electromagnetic-induction log every 10 min. The field data are analyzed and interpreted primarily through the use of Archie's (1942) law to investigate the role of topological factors such as pore geometry and connectivity, and grain size and packing configuration in regulating fluid flow through these coarse-grained materials. The logs reveal no significant correlation between K and ϕ, and imply that groundwater models that link these two properties may not be useful at this site. Rather, it is the distribution and connectivity of the fluid phase as defined by formation factor F, cementation index m, and tortuosity α that primarily control the hydraulic conductivity. Results show that F correlates well with K, thereby indicating that induction logs provide qualitative information on the distribution of hydraulic conductivity. A comparison of α, which incorporates porosity data, with K produces only a slightly better correlation and further emphasizes the weak influence of the bulk value of ϕ on K.

The influence of topology on hydraulic conductivity in a sand-and-gravel aquifer

USGS Publications Warehouse

Morin, R.H.; LeBlanc, D.R.; Troutman, B.M.

2010-01-01

A field experiment consisting of geophysical logging and tracer testing was conducted in a single well that penetrated a sand-and-gravel aquifer at the U.S. Geological Survey Toxic Substances Hydrology research site on Cape Cod, Massachusetts. Geophysical logs and flowmeter/pumping measurements were obtained to estimate vertical profiles of porosity ??, hydraulic conductivity K, temperature, and bulk electrical conductivity under background, freshwater conditions. Saline-tracer fluid was then injected into the well for 2 h and its radial migration into the surrounding deposits was monitored by recording an electromagnetic-induction log every 10 min. The field data are analyzed and interpreted primarily through the use of Archie's (1942) law to investigate the role of topological factors such as pore geometry and connectivity, and grain size and packing configuration in regulating fluid flow through these coarse-grained materials. The logs reveal no significant correlation between K and ??, and imply that groundwater models that link these two properties may not be useful at this site. Rather, it is the distribution and connectivity of the fluid phase as defined by formation factor F, cementation index m, and tortuosity ?? that primarily control the hydraulic conductivity. Results show that F correlates well with K, thereby indicating that induction logs provide qualitative information on the distribution of hydraulic conductivity. A comparison of ??, which incorporates porosity data, with K produces only a slightly better correlation and further emphasizes the weak influence of the bulk value of ?? on K. Copyright ?? 2009 The Author(s) are Federal Government Employees. Journal compilation ?? 2009 National Ground Water Association.

Longitudinal assessment of dairy farm management practices associated with the presence of psychrotolerant Bacillales spores in bulk tank milk on 10 New York State dairy farms.

PubMed

Masiello, S N; Kent, D; Martin, N H; Schukken, Y H; Wiedmann, M; Boor, K J

2017-11-01

The ability of certain spore-forming bacteria in the order Bacillales (e.g., Bacillus spp., Paenibacillus spp.) to survive pasteurization in spore form and grow at refrigeration temperatures results in product spoilage and limits the shelf life of high temperature, short time (HTST)-pasteurized fluid milk. To facilitate development of strategies to minimize contamination of raw milk with psychrotolerant Bacillales spores, we conducted a longitudinal study of 10 New York State dairy farms, which included yearlong monthly assessments of the frequency and levels of bulk tank raw milk psychrotolerant spore contamination, along with administration of questionnaires to identify farm management practices associated with psychrotolerant spore presence over time. Milk samples were first spore pasteurized (80°C for 12 min) and then analyzed for sporeformer counts on the initial day of spore pasteurization (SP), and after refrigerated storage (6°C) for 7, 14, and 21 d after SP. Overall, 41% of samples showed sporeformer counts of >20,000 cfu/mL at d 21, with Bacillus and Paenibacillus spp. being predominant causes of high sporeformer counts. Statistical analyses identified 3 management factors (more frequent cleaning of the bulk tank area, the use of a skid steer to scrape the housing area, and segregating problem cows during milking) that were all associated with lower probabilities of d-21 Bacillales spore detection in SP-treated bulk tank raw milk. Our data emphasize that appropriate on-farm measures to improve overall cleanliness and cow hygiene will reduce the probability of psychrotolerant Bacillales spore contamination of bulk tank raw milk, allowing for consistent production of raw milk with reduced psychrotolerant spore counts, which will facilitate production of HTST-pasteurized milk with extended refrigerated shelf life. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

The length of channelized lava flows: Insight from the 1859 eruption of Mauna Loa Volcano, Hawai‘i

NASA Astrophysics Data System (ADS)

Riker, Jenny M.; Cashman, Katharine V.; Kauahikaua, James P.; Montierth, Charlene M.

2009-06-01

The 1859 eruption of Mauna Loa Volcano, Hawai'i, produced paired 'a'ā and pāhoehoe flows of exceptional length (51 km). The 'a'ā flow field is distinguished by a long (> 36 km) and well-defined pāhoehoe-lined channel, indicating that channelized lava remained fluid to great distances from the vent. The 1859 eruption was further unusual in initiating at a radial vent on the volcano's northwest flank, instead of along the well-defined rift zone that has been the source of most historic activity. As such, it presents an opportunity both to examine controls on the emplacement of long lava channels and to assess hazards posed by future flank eruptions of Mauna Loa. Here we combine evidence from historical chronicles with analysis of bulk compositions, glass geothermometry, and microlite textures of samples collected along the 1859 lava flows to constrain eruption and flow emplacement conditions. The bulk compositions of samples from the 'a'ā and pāhoehoe flow fields are bimodally distributed and indicate tapping of two discrete magma bodies during eruption. Samples from the pāhoehoe flow field have bulk compositions similar to those of historically-erupted lavas (< 8 wt.% MgO); lava that fed the 'a'ā channel is more primitive (> 8 wt.% MgO), nearly aphyric, and was erupted at high temperatures (1194-1216 °C). We suggest that the physical properties of proximal channel-fed lava (i.e., high-temperature, low crystallinity, and low bulk viscosity) promoted both rapid flow advance and development of long pāhoehoe-lined channels. Critical for the latter was the large temperature decrease (~ 50 °C) required to reach the point at which plagioclase and pyroxene started to crystallize; the importance of phase constraints are emphasized by our difficulty in replicating patterns of cooling and crystallization recorded by high-temperature field samples using common models of flow emplacement. Placement of the 1859 eruption within the context of historic activity at Mauna Loa suggests that the formation of radial vents and eruptions of high-temperature magma may not only be linked, but may also be a consequence of periods of high magma supply (e.g., 1843-1877). Flank eruptions could therefore warrant special consideration in models and hazard mitigation efforts.

Advances in cryogenic engineering. Volume 27 - Proceedings of the Cryogenic Engineering Conference, San Diego, CA, August 11-14, 1981

NASA Technical Reports Server (NTRS)

Fast, R. W. (Editor)

1982-01-01

Applications of superconductivity are considered, taking into account MHD and fusion, generators, transformers, transmission lines, magnets for physics, cryogenic techniques, electrtronics, and aspects of magnet stability. Advances related to heat transfer in He I are discussed along with subjects related to theat transfer in He II, refrigeration of superconducting systems, refrigeration and liquefaction, dilution and magnetic refrigerators, refrigerators for space applications, mass transfer and flow phenomena, and the properties of fluids. Developments related to cryogenic applications are also explored, giving attention to bulk storage and transfer of cryogenic fluids, liquefied natural gas operations, space science and technology, and cryopumping. Topics related to cryogenic instrumentation and controls include the production and use of high grade silicon diode temperature sensors, the choice of strain gages for use in a large superconducting alternator, microprocessor control of cryogenic pressure, and instrumentation, data acquisition and reduction for a large spaceborne helium dewar.

Lattice Boltzmann Method for Spacecraft Propellant Slosh Simulation

NASA Technical Reports Server (NTRS)

Orr, Jeb S.; Powers, Joseph F.; Yang, Hong Q

2015-01-01

A scalable computational approach to the simulation of propellant tank sloshing dynamics in microgravity is presented. In this work, we use the lattice Boltzmann equation (LBE) to approximate the behavior of two-phase, single-component isothermal flows at very low Bond numbers. Through the use of a non-ideal gas equation of state and a modified multiple relaxation time (MRT) collision operator, the proposed method can simulate thermodynamically consistent phase transitions at temperatures and density ratios consistent with typical spacecraft cryogenic propellants, for example, liquid oxygen. Determination of the tank forces and moments is based upon a novel approach that relies on the global momentum conservation of the closed fluid domain, and a parametric wall wetting model allows tuning of the free surface contact angle. Development of the interface is implicit and no interface tracking approach is required. A numerical example illustrates the method's application to prediction of bulk fluid behavior during a spacecraft ullage settling maneuver.

Lattice Boltzmann Method for Spacecraft Propellant Slosh Simulation

NASA Technical Reports Server (NTRS)

Orr, Jeb S.; Powers, Joseph F.; Yang, Hong Q.

2015-01-01

A scalable computational approach to the simulation of propellant tank sloshing dynamics in microgravity is presented. In this work, we use the lattice Boltzmann equation (LBE) to approximate the behavior of two-phase, single-component isothermal flows at very low Bond numbers. Through the use of a non-ideal gas equation of state and a modified multiple relaxation time (MRT) collision operator, the proposed method can simulate thermodynamically consistent phase transitions at temperatures and density ratios consistent with typical spacecraft cryogenic propellants, for example, liquid oxygen. Determination of the tank forces and moments relies upon the global momentum conservation of the fluid domain, and a parametric wall wetting model allows tuning of the free surface contact angle. Development of the interface is implicit and no interface tracking approach is required. Numerical examples illustrate the method's application to predicting bulk fluid motion including lateral propellant slosh in low-g conditions.

Transformation of MT Resistivity Sections into Geologically Meaningful Images

NASA Astrophysics Data System (ADS)

Park, S. K.

2004-05-01

Earthscope offers an unprecedented opportunity for interdisciplinary studies of North America. In addition to a continent-wide seismic study, it includes the acquisition of magnetotelluric (MT) data at many of the Bigfoot array sites. Earthscope will thus provide a uniform 3-D MT survey over regional scales when completed. MT interpreters will be able to include 3-D regional effects in their models for the first time whether they are interpreting local studies. However, the full value of the interdisciplinary nature of Earthscope will be realized only if MT sections and maps are useful to other earth scientists. The standard final product from any 2-D or 3-D MT interpretation is a spatial distribution of electrical resistivity. Inference of the physicochemical state from bulk resistivity is complicated because a variety of factors influence the property including temperature, intrinsic conduction of silicates, and small amounts of interconnected conducting materials (e.g., graphite, metallic minerals, partial melt, fluid). Here, I use petrophysical measurements and a petrological model to transform a resistivity section into cross sections of temperature and partial melt fraction in the mantle beneath the Sierra Nevada. In this manner, I am able to separate the contributions of increasing temperature and melt fraction to the bulk resistivity. Predicted melt fractions match observations from xenoliths relatively well but temperatures are systematically 200C higher than those observed. A small amount of dissolved hydrogen (~70 ppm H/Si) lowers the predicted temperatures to match those from the xenoliths, however. I conclude that while this transformation is a simple first step based on many assumptions, initial results are promising.

Thermo-mechanical Properties of Upper Jurassic (Malm) Carbonate Rock Under Drained Conditions

NASA Astrophysics Data System (ADS)

Pei, Liang; Blöcher, Guido; Milsch, Harald; Zimmermann, Günter; Sass, Ingo; Huenges, Ernst

2018-01-01

The present study aims to quantify the thermo-mechanical properties of Neuburger Bankkalk limestone, an outcrop analog of the Upper Jurassic carbonate formation (Germany), and to provide a reference for reservoir rock deformation within future enhanced geothermal systems located in the Southern German Molasse Basin. Experiments deriving the drained bulk compressibility C were performed by cycling confining pressure p c between 2 and 50 MPa at a constant pore pressure p p of 0.5 MPa after heating the samples to defined temperatures between 30 and 90 °C. Creep strain was then measured after each loading and unloading stage, and permeability k was obtained after each creep strain measurement. The drained bulk compressibility increased with increasing temperature and decreased with increasing differential pressure p d = p c - p p showing hysteresis between the loading and unloading stages above 30 °C. The apparent values of the indirectly calculated Biot coefficient α ind containing contributions from inelastic deformation displayed the same temperature and pressure dependencies. The permeability k increased immediately after heating and the creep rates were also temperature dependent. It is inferred that the alteration of the void space caused by temperature changes leads to the variation of rock properties measured under isothermal conditions while the load cycles applied under isothermal conditions yield additional changes in pore space microstructure. The experimental results were applied to a geothermal fluid production scenario to constrain drawdown and time-dependent effects on the reservoir, overall, to provide a reference for the hydromechanical behavior of geothermal systems in carbonate, and more specifically, in Upper Jurassic lithologies.

Estimates of olivine-basaltic melt electrical conductivity using a digital rock physics approach

NASA Astrophysics Data System (ADS)

Miller, Kevin J.; Montési, Laurent G. J.; Zhu, Wen-lu

2015-12-01

Estimates of melt content beneath fast-spreading mid-ocean ridges inferred from magnetotelluric tomography (MT) vary between 0.01 and 0.10. Much of this variation may stem from a lack of understanding of how the grain-scale melt geometry influences the bulk electrical conductivity of a partially molten rock, especially at low melt fraction. We compute bulk electrical conductivity of olivine-basalt aggregates over 0.02 to 0.20 melt fraction by simulating electric current in experimentally obtained partially molten geometries. Olivine-basalt aggregates were synthesized by hot-pressing San Carlos olivine and high-alumina basalt in a solid-medium piston-cylinder apparatus. Run conditions for experimental charges were 1.5 GPa and 1350 °C. Upon completion, charges were quenched and cored. Samples were imaged using synchrotron X-ray micro-computed tomography (μ-CT). The resulting high-resolution, 3-dimensional (3-D) image of the melt distribution constitutes a digital rock sample, on which numerical simulations were conducted to estimate material properties. To compute bulk electrical conductivity, we simulated a direct current measurement by solving the current continuity equation, assuming electrical conductivities for olivine and melt. An application of Ohm's Law yields the bulk electrical conductivity of the partially molten region. The bulk electrical conductivity values for nominally dry materials follow a power-law relationship σbulk = Cσmeltϕm with fit parameters m = 1.3 ± 0.3 and C = 0.66 ± 0.06. Laminar fluid flow simulations were conducted on the same partially molten geometries to obtain permeability, and the respective pathways for electrical current and fluid flow over the same melt geometry were compared. Our results indicate that the pathways for flow fluid are different from those for electric current. Electrical tortuosity is lower than fluid flow tortuosity. The simulation results are compared to existing experimental data, and the potential influence of volatiles and melt films on electrical conductivity of partially molten rocks is discussed.

A Fundamental Study of Nucleate Pool Boiling Under Microgravity

NASA Technical Reports Server (NTRS)

Ervin, Jamie S.; Merte, Herman, Jr.

1996-01-01

An experimental study of incipient boiling in short-term microgravity and with a/g = +/- 1 for pool boiling was performed. Calibrated thin gold films sputtered on a smoothly polished quartz surface were used simultaneously for thermal-resistance measurements and heating of the boiling surface. The gold films were used for both transient and quasi-steady heating surface temperature measurements. Two test vessels were constructed for precise measurement and control of fluid temperature and pressure: a laboratory pool boiling vessel for the a/g = +/- 1 experiments and a pool boiling vessel designed for the 131 m free-fall in the NASA Lewis Research Center Microgravity Research Facility for the microgravity tests. Measurements included the heater surface temperature, the pressure near the heating surface, the bulk liquid temperatures. High speed photography (up to 1,000 frames per second) was used in the experiments. With high quality microgravity and the measured initial temperature of the quiescent test fluid, R113, the temperature distribution in the liquid at the moment of boiling inception resulting from an imposed step in heat flux is known with a certainty not possible previously. The types of boiling propagation across the large flat heating surface, some observed here for the first time, are categorized; the conditions necessary for their occurrence are described. Explosive boiling propagation with a striking pattern of small scale protuberances over the entire vapor mass periphery not observed previously at low heat flux levels (on the order of 5 W/cm(exp 2)) is described. For the heater surface with a/g = -1, a step in the heater surface temperature of short duration was imposed. The resulting liquid temperature distribution at the moment of boiling inception was different from that obtained with a step in heat flux.

On the adsorption properties of magnetic fluids: Impact of bulk structure

NASA Astrophysics Data System (ADS)

Kubovcikova, Martina; Gapon, Igor V.; Zavisova, Vlasta; Koneracka, Martina; Petrenko, Viktor I.; Soltwedel, Olaf; Almasy, László; Avdeev, Mikhail V.; Kopcansky, Peter

2017-04-01

Adsorption of nanoparticles from magnetic fluids (MFs) on solid surface (crystalline silicon) was studied by neutron reflectometry (NR) and related to the bulk structural organization of MFs concluded from small-angle neutron scattering (SANS). The initial aqueous MF with nanomagnetite (co-precipitation reaction) stabilized by sodium oleate and MF modified by a biocompatible polymer, poly(ethylene glycol) (PEG), were considered. Regarding the bulk structure it was confirmed in the SANS experiment that comparatively small and compact (size 30 nm) aggregates of nanoparticle in the initial sample transfer to large and developed (size>130 nm, fractal dimension 2.7) associates in the PEG modified MF. This reorganization in the aggregates correlates with the changes in the neutron reflectivity that showed that a single adsorption layer of individual nanoparticles on the oxidized silicon surface for the initial MF disappears after the PEG modification. It is concluded that all particles in the modified fluid are in the aggregates that are not adsorbed by silicon.

Confinement effects on liquid oxygen flows in carbon nanotubes: A MD simulation study

NASA Astrophysics Data System (ADS)

Suga, Kazuhiko; Moritani, Rintaro; Mori, Yuki; Kaneda, Masayuki

2017-11-01

Molecular dynamics simulations are performed to investigate the liquid flow mechanism of diatomic molecules in armchair carbon nanotubes (CNTs). Oxygen molecules are considered as the fluid inside armchair (n,n) (n=6-20) CNTs at a temperature of 133[K] and a bulk density of 1680[kg /m3] for the liquid state. The velocity profiles and slip lengths are discussed considering the radial distributions of the fluid density by the finite difference-based velocity fitting method. It is shown that as the diameter of the CNT increases, the slip length and the flow rate enhancement generally become smaller while irregular tendencies (discontinuity points) are observed in the distribution profiles. Between the (7,7) and (8,8) CNTs, a steep drop can be seen in the profiles. Between the (9,9) and (11,11) CNTs, and between the (12,12) and (14,14) CNTs transitional profiles are observed. It is confirmed that those phenomena are caused by an instability of the fluid molecule cluster due to the discontinuous confinement of the CNTs. Professor.

Using second-sound shock waves to probe the intrinsic critical velocity of liquid helium II

NASA Technical Reports Server (NTRS)

Turner, T. N.

1983-01-01

A critical velocity truly intrinsic to liquid helium II is experimentally sought in the bulk fluid far from the apparatus walls. Termed the 'fundamental critical velocity,' it necessarily is caused by mutual interactions which operate between the two fluid components and which are activated at large relative velocities. It is argued that flow induced by second-sound shock waves provides the ideal means by which to activate and isolate the fundamental critical velocity from other extraneous fluid-wall interactions. Experimentally it is found that large-amplitude second-sound shock waves initiate a breakdown in the superfluidity of helium II, which is dramatically manifested as a limit to the maximum attainable shock strength. This breakdown is shown to be caused by a fundamental critical velocity. Secondary effects include boiling for ambient pressures near the saturated vapor pressure or the formation of helium I boundary layers at higher ambient pressures. When compared to the intrinsic critical velocity discovered in highly restricted geometries, the shock-induced critical velocity displays a similar temperature dependence and is the same order of magnitude.

Crossing the phantom divide with dissipative normal matter in the Israel-Stewart formalism

NASA Astrophysics Data System (ADS)

Cruz, Norman; Lepe, Samuel

2017-04-01

A phantom solution in the framework of the causal Israel-Stewart (IS) formalism is discussed. We assume a late time behavior of the cosmic evolution by considering only one dominant matter fluid with viscosity. In the model it is assumed a bulk viscosity of the form ξ =ξ0ρ 1 / 2, where ρ is the energy density of the fluid. We evaluate and discuss the behavior of the thermodynamical parameters associated to this solution, like the temperature, rate of entropy, entropy, relaxation time, effective pressure and effective EoS. A discussion about the assumption of near equilibrium of the formalism and the accelerated expansion of the solution is presented. The solution allows to cross the phantom divide without evoking an exotic matter fluid and the effective EoS parameter is always lesser than -1 and time independent. A future singularity (big rip) occurs, but different from the Type I (big rip) solution classified in S. Nojiri, S.D. Odintsov and S. Tsujikawa (2005) [2], if we consider other thermodynamics parameters like, for example, the effective pressure in the presence of viscosity or the relaxation time.

An estimate of the bulk viscosity of the hadronic medium

NASA Astrophysics Data System (ADS)

Sarwar, Golam; Chatterjee, Sandeep; Alam, Jane

2017-05-01

The bulk viscosity (ζ) of the hadronic medium has been estimated within the ambit of the Hadron Resonance Gas (HRG) model including the Hagedorn density of states. The HRG thermodynamics within a grand canonical ensemble provides the mean hadron number as well as its fluctuation. The fluctuation in the chemical composition of the hadronic medium in the grand canonical ensemble can result in non-zero divergence of the hadronic fluid flow velocity, allowing us to estimate the ζ of the hadronic matter up to a relaxation time. We study the influence of the hadronic spectrum on ζ and find its correlation with the conformal symmetry breaking measure, ε -3P. We estimate ζ along the contours with constant, S/{N}B (total entropy/net baryon number) in the T-μ plane (temperature-baryonic chemical potential) for S/{N}B=30,45 and 300. We also assess the value of ζ on the chemical freeze-out curve for various centers of mass energy (\\sqrt{{s}{NN}}) and find that the bulk viscosity to entropy density ratio, \\zeta /s is larger in the energy range of the beam energy scan program of RHIC, low energy SPS run, AGS, NICA and FAIR, than LHC energies.

Aggregation of concentrated monoclonal antibody solutions studied by rheology and neutron scattering

NASA Astrophysics Data System (ADS)

Castellanos, Maria Monica; Pathak, Jai; Colby, Ralph

2013-03-01

Protein solutions are studied using rheology and scattering techniques to investigate aggregation. Here we present a monoclonal antibody (mAb) that aggregates after incubation at 40 °C (below its unfolding temperature), with a decrease in monomer purity of 6% in 10 days. The mAb solution contains surfactant and behaves as a Newtonian fluid when reconstituted into solution from the lyophilized form (before incubation at 40 °C). In contrast, mAb solutions incubated at 40 °C for 1 month exhibit shear yielding in torsional bulk rheometers. Interfacial rheology reveals that interfacial properties are controlled by the surfactant, producing a negligible surface contribution to the bulk yield stress. These results provide evidence that protein aggregates formed in the bulk are responsible for the yield stress. Small-angle neutron scattering (SANS) measurements show an increase in intensity at low wavevectors (q < 4*10-2 nm-1) that we attribute to protein aggregation, and is not observed in solutions stored at 4 °C for 3 days before the measurement. This work suggests a correlation between the aggregated state of the protein (stability) and the yield stress from rheology. Research funded by MedImmune

The incompressible Rindler fluid versus the Schwarzschild-AdS fluid

NASA Astrophysics Data System (ADS)

Matsuo, Yoshinori; Natsuume, Makoto; Ohta, Masahiro; Okamura, Takashi

2013-02-01

We study the proposal by Bredberg et al. [J. High Energy Phys. 1103, 141 (2011)], where the fluid is defined by the Brown-York tensor on a timelike surface at r = rc in black hole backgrounds. We consider both Rindler space and the Schwarzschild-AdS (SAdS) black hole. The former describes an incompressible fluid, whereas the latter describes the vanishing bulk viscosity at arbitrary rc. Although the near-horizon limit of the SAdS black hole is Rindler space, these two results do not contradict each other. We also find an interesting "coincidence" with the black hole membrane paradigm that gives a negative bulk viscosity. In order to show these results, we rewrite the hydrodynamic stress tensor via metric perturbations using the conservation equation. The resulting expressions are suitable to compare with the Brown-York tensor.

Predicting the pKa and stability of organic acids and bases at an oil-water interface.

PubMed

Andersson, M P; Olsson, M H M; Stipp, S L S

2014-06-10

We have used density functional theory and the implicit solvent model, COSMO-RS, to investigate how the acidity constant, pKa, of organic acids and bases adsorbed at the organic compound-aqueous solution interface changes, compared to its value in the aqueous phase. The pKa determine the surface charge density of the molecules that accumulate at the fluid-fluid interface. We have estimated the pKa by comparing the stability of the protonated and unprotonated forms of a series of molecules in the bulk aqueous solution and at an interface where parts of each molecule reside in the hydrophobic phase and the rest remains in the hydrophilic phase. We found that the pKa for acids is shifted by ∼1 pH unit to higher values compared to the bulk water pKa, whereas they are shifted to lower values by a similar amount for bases. Because this pKa shift is similar in magnitude for each of the molecules studied, we propose that the pKa for molecules at a water-organic compound interface can easily be predicted by adding a small shift to the aqueous pKa. This shift is general and correlates with the functional group. We also found that the relative composition of molecules at the fluid-fluid interface is not the same as in the bulk. For example, species such as carboxylic acids are enriched at the interface, where they can dominate surface properties, even when they are a modest component in the bulk fluid. For high surface concentrations of carboxylic acid groups at an interface, such as a self-assembled monolayer, we have demonstrated that the pKa depends on the degree of deprotonation through direct hydrogen bonding between protonated and deprotonated acidic headgroups.

The effect of artificial bulk viscosity in simulations of forced compressible turbulence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Campos, A.; Morgan, B.

The use of an artificial bulk viscosity for shock stabilization is a common approach employed in turbulence simulations with high-order numerics. The effect of the artificial bulk viscosity is analyzed in the context of large eddy simulations by using as a test case simulations of linearly-forced compressible homogeneous turbulence (Petersen and Livescu, 2010 [12]). This case is unique in that it allows for the specification of a priori target values for total dissipation and ratio of solenoidal to dilatational dissipation. A comparison between these target values and the true predicted levels of dissipation is thus used to investigate the performancemore » of the artificial bulk viscosity. Results show that the artificial bulk viscosity is effective at achieving stable solutions, but also leads to large values of artificial dissipation that outweigh the physical dissipation caused by fluid viscosity. An alternate approach, which employs the artificial thermal conductivity only, shows that the dissipation of dilatational modes is entirely due to the fluid viscosity. However, this method leads to unwanted Gibbs oscillations around the shocklets. The use of shock sensors that further localize the artificial bulk viscosity did not reduce the amount of artificial dissipation introduced by the artificial bulk viscosity. Finally, an improved forcing function that explicitly accounts for the role of the artificial bulk viscosity in the budget of turbulent kinetic energy was explored.« less

The effect of artificial bulk viscosity in simulations of forced compressible turbulence

DOE PAGES

Campos, A.; Morgan, B.

2018-05-17

The use of an artificial bulk viscosity for shock stabilization is a common approach employed in turbulence simulations with high-order numerics. The effect of the artificial bulk viscosity is analyzed in the context of large eddy simulations by using as a test case simulations of linearly-forced compressible homogeneous turbulence (Petersen and Livescu, 2010 [12]). This case is unique in that it allows for the specification of a priori target values for total dissipation and ratio of solenoidal to dilatational dissipation. A comparison between these target values and the true predicted levels of dissipation is thus used to investigate the performancemore » of the artificial bulk viscosity. Results show that the artificial bulk viscosity is effective at achieving stable solutions, but also leads to large values of artificial dissipation that outweigh the physical dissipation caused by fluid viscosity. An alternate approach, which employs the artificial thermal conductivity only, shows that the dissipation of dilatational modes is entirely due to the fluid viscosity. However, this method leads to unwanted Gibbs oscillations around the shocklets. The use of shock sensors that further localize the artificial bulk viscosity did not reduce the amount of artificial dissipation introduced by the artificial bulk viscosity. Finally, an improved forcing function that explicitly accounts for the role of the artificial bulk viscosity in the budget of turbulent kinetic energy was explored.« less

Performance of journal bearings with semi-compressible fluids

NASA Technical Reports Server (NTRS)

Carpino, M.; Peng, J.-P.

1991-01-01

Cryogenic fluids in isothermal rigid surface and foil type journal bearings can sometimes be treated as semicompressible fluids. In these applications, the fluid density is a function of the pressure. At low pressures, the fluids can change from a liquid to a saturated liquid-vapor phase. The performance of a rigid surface journal bearing with an idealized semicompressible fluid is discussed. Pressure solutions are based upon a Reynolds equation which includes the effects of a compressibility via the bulk modulus of the fluid. Results are contrasted with the performance of isothermal constant property incompressible fluids.

Fluid inclusion studies of the Rodeo de Los Molles REE and Th deposit, Las Chacras Batholith, Central Argentina

NASA Astrophysics Data System (ADS)

Lira, Raul; Ripley, Edward M.

1990-03-01

The Rodeo de Los Molles rare earth element (REE) and thorium deposit is located in granitic rocks of the Las Chacras-Piedras Coloradas Batholith, in the southern block of the Eastern Pampean Ranges, Central Argentina. Mineralization occurs within an elongate (2 km × 0.6 km) body of alkalifeldspar granite (alaskite) localized along the northeastern edge of a composite batholith. The surrounding lithology is predominantly a biotite monzogranite. Both the alaskite and localized areas of quartz alkalifeldspar syenite within the alaskite have been produced by hydrothermal alteration of a late-crystallizing phase of the monzogranite. REE minerals are primarily of the cerium group and include britholite and allanite, both partially replaced by bastnaesite or thorbastnaesite. These minerals occur as nodules with quartz, fluorite, aegirine-augite, sphene, and Fe-Ti oxides within aplitic to pegmatoidal quartz alkalifeldspar syenite. Uranothorite, along with a second generation of fluorite and minor amounts of MnBa oxides, occurs in the alaskite as nodules, or within quartz-lined miarolitic cavities, but is not found with the Ce-mineralization. Studies of fluid inclusions contained in quartz and fluorite indicate a complex history of open-system fluid migration and interaction with monzogranite host rocks. Fluids responsible for REE mineralization and quartz deposition, along with initial alteration of the monzogranite to alaskite and quartz alkalifeldspar syenite, were of relatively high temperature (T h of fluid inclusions in quartz = 356-535°C) and moderate salinity (15-25 eq. wt% NaCl). Mixed CO 2H 2O fluids (XCO 2 = .13-.07) found as both primary and secondary inclusions within fluorite are representative of fluids involved in the replacement of britholite-allanite by bastnaesite and sphene, aegirine-augite, and plagioclase by calcite. Minimum pressures of mineral deposition estimated from H 2OCO 2NaCl phase relations range from 1 to 2 kbars. Secondary aqueous fluid inclusions in quartz define a trend of low salinity-high temperature to high salinity-low temperature, thought to be a result of hydration reactions occurring in alaskite and quartz alkali-feldspar syenite. The highest salinity fluids (35-37 eq. wt% NaCl) detected in the area are associated with the formation of uranothorite and late fluorite. Multiple periods of hydrothermal fluid introduction are consistent with recent geological data that indicate that the batholith is composed of several stock-like bodies. The location of the mineralized area near the top of the magma chamber, the presence of numerous miarolitic cavities, and the bulk composition of inclusion fluids (Na ≥ K > Ca) suggest that the fluids responsible for REE and Th mineralization were of magmatic origin.

The La Unión Au ± Cu prospect, Camagüey District, Cuba: fluid inclusion and stable isotope evidence for ore-forming processes

NASA Astrophysics Data System (ADS)

Santana, Miriela María Ulloa; Moura, Márcia Abrahão; Olivo, Gema R.; Botelho, Nilson Francisquini; Kyser, T. Kurtis; Bühn, Bernhard

2011-01-01

The Camagüey district, Cuba, is known for its epithermal precious metal deposits in a Cretaceous volcanic arc setting. Recently, the La Unión prospect was discovered in the southern part of the district, containing gold and minor copper mineralization interpreted as porphyry type. Mineralization is hosted in a 73.0 ± 1.5 Ma calc-alkaline I-type oxidized porphyry quartz diorite intrusive within volcanic and volcaniclastic rocks of the early Cretaceous Guáimaro Formation. The porphyry is affected by propylitic alteration and crosscut by a network of quartz and carbonate veinlets and veins. Chlorite, epidote, sericite, quartz, and pyrite are the main minerals in the early veins which are cut by late carbonate and zeolite veins. Late barite pseudomorphously replaces pyrite. Gold is associated with pyrite as disseminations in the altered quartz diorite and in the veins, occurring as inclusions or filling fractures in pyrite with 4 g/t Au in bulk samples, and up to 900 ppm Au in in pyrite. Fluid inclusion and oxygen isotope data are consistent with a H2O-NaCl-(KCl) mineralizing fluid, derived from the quartz diorite magma, and trapped at least at 425°C and 1.2 kbar. This primary fluid unmixed into two fluid phases, a hypersaline aqueous fluid and a low-salinity vapor-rich fluid. Boiling during cooling may have played an important role in metal precipitation. Pyrite δ34S values for the La Unión prospect range between 0.71‰ and 1.31‰, consistent with a homogeneous magmatic sulfur source. The fluids in equilibrium with the mineralized rocks have estimated δ18O values from 8‰ to 11.8‰, calculated for a temperature range of 480-505°C. The tectonic environment of the La Unión prospect, its high gold and low copper contents, the physical-chemical characteristics of the mineralizing fluids and the isotopic signature of the alteration minerals and fluids indicate that the La Unión gold mineralization is similar to the porphyry gold type, even though the ore-related epidote-chlorite alteration can be classified as propylitic and not the classic potassic and/or phyllic alteration. The low copper contents in the prospect could be due to a mineralizing fluid previously saturated in copper, which is indicated by trapped chalcopyrite crystals in high-temperature fluid inclusions. The low-temperature paragenesis, represented by carbonate, zeolite and barite, indicates epithermal overprint. The study shows the potential for other gold porphyry-type deposits in the Cretaceous volcanoplutonic arc of Cuba.

Sulfate brines in fluid inclusions of hydrothermal veins: Compositional determinations in the system H2O-Na-Ca-Cl-SO4

NASA Astrophysics Data System (ADS)

Walter, Benjamin F.; Steele-MacInnis, Matthew; Markl, Gregor

2017-07-01

Sulfate is among the most abundant ions in seawater and sulfate-bearing brines are common in sedimentary basins, among other environments. However, the properties of sulfate-bearing fluid inclusions during microthermometry are as yet poorly constrained, restricting the interpretation of fluid-inclusion compositions where sulfate is a major ion. The Schwarzwald mining district on the eastern shoulder of the Upper Rhinegraben rift is an example of a geologic system characterized by sulfate-bearing brines, and constraints on the anion abundances (chloride versus sulfate) would be desirable as a potential means to differentiate fluid sources in hydrothermal veins in these regions. Here, we use the Pitzer-type formalism to calculate equilibrium conditions along the vapor-saturated liquidus of the system H2O-Na-Ca-Cl-SO4, and construct phase diagrams displaying the predicted phase equilibria. We combine these predicted phase relations with microthermometric and crush-leach analyses of fluid inclusions from veins in the Schwarzwald and Upper Rhinegraben, to estimate the compositions of these brines in terms of bulk salinity as well as cation and anion loads (sodium versus calcium, and chloride versus sulfate). These data indicate systematic differences in fluid compositions recorded by fluid inclusions, and demonstrate the application of detailed low-temperature microthermometry to determine compositions of sulfate-bearing brines. Thus, these data provide new constraints on fluid sources and paleo-hydrology of these classic basin-hosted ore-forming systems. Moreover, the phase diagrams presented herein can be applied directly to compositional determinations in other systems.

Aerial thermography studies of power plant heated lakes

NASA Astrophysics Data System (ADS)

Villa-Aleman, Eliel; Garrett, Alfred J.; Kurzeja, Robert J.; Pendergast, Malcolm M.

2000-03-01

Remote sensing temperature measurements of water bodies is complicated by the temperature differences between the true surface or `skin' water and the bulk water below. Weather conditions control the reduction of the skin temperature relative to the bulk water temperature. Typical skin temperature depressions range from a few tenths of a degree Celsius to more than one degree. In this research project, the Savannah River Technology Center used aerial thermography and surface-based meteorological and water temperature measurements to study a power plant cooling lake in South Carolina. Skin and bulk water temperatures were measured simultaneously for imagery calibration and to product a database for modeling of skin temperature depressions as a function of weather and bulk water temperatures. This paper will present imagery that illustrates how the skin temperature depression was affected by different conditions in several locations on the lake and will present skin temperature modeling results.

Geochronology, fluid inclusions and isotopic characteristics of the Chaganbulagen Pb-Zn-Ag deposit, Inner Mongolia, China

NASA Astrophysics Data System (ADS)

Li, Tiegang; Wu, Guang; Liu, Jun; Wang, Guorui; Hu, Yanqing; Zhang, Yunfu; Luo, Dafeng; Mao, Zhihao; Xu, Bei

2016-09-01

The large Chaganbulagen Pb-Zn-Ag deposit is located in the Derbugan metallogenic belt of the northern Great Xing'an Range. The vein-style orebodies of the deposit occur in the NWW-trending fault zones. The ore-forming process at the deposit can be divided into three stages: an early quartz-pyrite-arsenopyrite-pyrrhotite-sphalerite-galena-chalcopyrite stage, a middle quartz-carbonate-pyrite-sphalerite-galena-silver-bearing minerals stage, and a late quartz-carbonate-pyrite stage. The sericite sample yielded a 40Ar -39Ar plateau age of 138 ± 1 Ma and an isochron age of 137 ± 3 Ma, and the zircon LA-ICP-MS U-Pb age of monzogranite porphyry was 143 ± 2 Ma, indicating that the ages of mineralization and monzogranite porphyry in the Chaganbulagen deposit should be the Early Cretaceous, and that the mineralization should be slightly later than the intrusion of monzogranite porphyry. There are only liquid inclusions in quartz veins of the Chaganbulagen deposit. Homogenization temperatures, densities, and salinities of the fluid inclusions from the early stage are 261-340 °C, 0.65-0.81 g/cm3, and 0.7-6.3 wt.% NaCl eqv., respectively. Fluid inclusions of the middle stage have homogenization temperatures, densities, and salinities of 209-265 °C, 0.75-0.86 g/cm3, and 0.5-5.7 wt.% NaCl eqv., respectively. For fluid inclusions of the late stage, their homogenization temperatures, densities, and salinities are 173-219 °C, 0.85-0.91 g/cm3, and 0.4-2.7 wt.% NaCl eqv., respectively. The ore-forming fluids of the deposit are generally characterized by moderate temperature and low salinity and density, and belong to an H2O-NaCl ± CO2 ± CH4 system. The δ18Owater values calculated for ore-bearing quartz vary from - 17.9‰ to - 10.8‰, and the δDV-SMOW values from bulk extraction of fluid inclusion waters vary from - 166‰ to - 127‰, suggesting that the ore-forming fluids consist dominantly of meteoric water. The δ34SV-CDT values range from 1.4‰ to 4.1‰. The 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb values of the ore minerals are in the ranges of 18.302-19.037, 15.473-15.593, and 38.110-38.945, respectively. The data for the S and Pb isotopic systems indicate that the ore-forming metals and sulfur came from Mesozoic magma. The Chaganbulagen deposit is a low-sulfidation epithermal Pb-Zn-Ag deposit, and the temperature decrease is the dominant mechanism for the deposition of ore-forming materials.

Development and Validation of Computational Fluid Dynamics Models for Prediction of Heat Transfer and Thermal Microenvironments of Corals

PubMed Central

Ong, Robert H.; King, Andrew J. C.; Mullins, Benjamin J.; Cooper, Timothy F.; Caley, M. Julian

2012-01-01

We present Computational Fluid Dynamics (CFD) models of the coupled dynamics of water flow, heat transfer and irradiance in and around corals to predict temperatures experienced by corals. These models were validated against controlled laboratory experiments, under constant and transient irradiance, for hemispherical and branching corals. Our CFD models agree very well with experimental studies. A linear relationship between irradiance and coral surface warming was evident in both the simulation and experimental result agreeing with heat transfer theory. However, CFD models for the steady state simulation produced a better fit to the linear relationship than the experimental data, likely due to experimental error in the empirical measurements. The consistency of our modelling results with experimental observations demonstrates the applicability of CFD simulations, such as the models developed here, to coral bleaching studies. A study of the influence of coral skeletal porosity and skeletal bulk density on surface warming was also undertaken, demonstrating boundary layer behaviour, and interstitial flow magnitude and temperature profiles in coral cross sections. Our models compliment recent studies showing systematic changes in these parameters in some coral colonies and have utility in the prediction of coral bleaching. PMID:22701582

T-XCO2 stability relations and phase equilibria of a calcic carbonate scapolite

USGS Publications Warehouse

Aitken, B.G.

1983-01-01

At a total pressure of 5 kb, calcic, Cl-free scapolite (Me83) is stable relative to plagioclase-bearing assemblages at T ??? 625??C, XCO2 ??? 0.12. With decreasing temperature, scapolite breaks down to plagioclase + calcite. Scapolite is replaced by plagioclase + grossular + cancrinite + CO2 in the presence of H2O-rich fluids. The stable coexistence of scapolite and calcite, an assemblage typical of most natural occurrences of calcic scapolite, is limited by the reaction: scapolite + calcite ??? grossular + cancrinite + CO2, which occurs at 750??C, XCO2 = 0.46; 700??C, XCO2 = 0.33; 650??C, XCO2 = 0.18, for the chosen bulk composition. Generalization of the experimental results to encompass the complete range of fully carbonated scapolite compositions indicates that mizzonite (Me75) has the largest T-XCO2 stability field. For scapolite more calcic than mizzonite, stable growth is restricted to conditions of increasingly higher temperature and XCO2. The experimental results are consistent with various petrologic features of scapolite-bearing rocks, particularly scapolite-clinopyroxene granulites, and indicate that such rocks were formed in the presence of CO2-rich fluids. ?? 1983.

Temperature-dependent poroelastic and viscoelastic effects on microscale-modelling of seismic reflections in heavy oil reservoirs

NASA Astrophysics Data System (ADS)

Ciz, Radim; Saenger, Erik H.; Gurevich, Boris; Shapiro, Serge A.

2009-03-01

We develop a new model for elastic properties of rocks saturated with heavy oil. The heavy oil is represented by a viscoelastic material, which at low frequencies and/or high temperatures behaves as a Newtonian fluid, and at high frequencies and/or low temperatures as a nearly elastic solid. The bulk and shear moduli of a porous rock saturated with such viscoelastic material are then computed using approximate extended Gassmann equations of Ciz and Shapiro by replacing the elastic moduli of the pore filling material with complex and frequency-dependent moduli of the viscoelastic pore fill. We test the proposed model by comparing its predictions with numerical simulations based on a direct finite-difference solution of equations of dynamic viscoelasticity. The simulations are performed for the reflection coefficient from an interface between a homogeneous fluid and a porous medium. The numerical tests are performed both for an idealized porous medium consisting of alternating solid and viscoelastic layers, and for a more realistic 3-D geometry of the pore space. Both sets of numerical tests show a good agreement between the predictions of the proposed viscoelastic workflow and numerical simulations for relatively high viscosities where viscoelastic effects are important. The results confirm that application of extended Gassmann equations in conjunction with the complex and frequency-dependent moduli of viscoelastic pore filling material, such as heavy oil, provides a good approximation for the elastic moduli of rocks saturated with such material. By construction, this approximation is exactly consistent with the classical Gassmann's equation for sufficiently low frequencies or high temperature when heavy oil behaves like a fluid. For higher frequencies and/or lower temperatures, the predictions are in good agreement with the direct numerical solution of equations of dynamic viscoelasticity on the microscale. This demonstrates that the proposed methodology provides realistic estimates of elastic properties of heavy oil rocks.

The equation of state of n-pentane in the atomistic model TraPPE-EH

NASA Astrophysics Data System (ADS)

Valeev, B. U.; Pisarev, V. V.

2018-01-01

In this work, we study the vapor-liquid equilibrium in n-pentane. We use the TraPPE-EH (transferable potentials for phase equilibria-explicit hydrogen) forcefield, where each hydrogen and carbon atom is considered as independent center of force. The fluid behavior was investigated with different values of density and temperature by molecular dynamics method. The n-pentane evaporation curve was calculated in the temperature range of 290 to 390 K. The densities of the coexisting phases are also calculated. The compression curve at 370 K was calculated and isothermal bulk modulus was found. The simulated properties of n-pentane are in good agreement with data from a database of the National Institute of Standards and Technology, so the TraPPE-EH model can be recommended for simulations of hydrocarbons.

Effects of flow on insulin fibril formation at an air/water interface

NASA Astrophysics Data System (ADS)

Posada, David; Heldt, Caryn; Sorci, Mirco; Belfort, Georges; Hirsa, Amir

2009-11-01

The amyloid fibril formation process, which is implicated in several diseases such as Alzheimer's and Huntington's, is characterized by the conversion of monomers to oligomers and then to fibrils. Besides well-studied factors such as pH, temperature and concentration, the kinetics of this process are significantly influenced by the presence of solid or fluid interfaces and by flow. By studying the nucleation and growth of a model system (insulin fibrils) in a well-defined flow field with an air/water interface, we can identify the flow conditions that impact protein aggregation kinetics both in the bulk solution and at the air/water interface. The present flow system (deep-channel surface viscometer) consists of an annular region bounded by stationary inner and outer cylinders, an air/water interface, and a floor driven at constant rotation. We show the effects of Reynolds number on the kinetics of the fibrillation process both in the bulk solution and at the air/water interface, as well as on the structure of the resultant amyloid aggregates.

Momentum and charge transport in non-relativistic holographic fluids from Hořava gravity

NASA Astrophysics Data System (ADS)

Davison, Richard A.; Grozdanov, Sašo; Janiszewski, Stefan; Kaminski, Matthias

2016-11-01

We study the linearized transport of transverse momentum and charge in a conjectured field theory dual to a black brane solution of Hořava gravity with Lifshitz exponent z = 1. As expected from general hydrodynamic reasoning, we find that both of these quantities are diffusive over distance and time scales larger than the inverse temperature. We compute the diffusion constants and conductivities of transverse momentum and charge, as well the ratio of shear viscosity to entropy density, and find that they differ from their relativistic counterparts. To derive these results, we propose how the holographic dictionary should be modified to deal with the multiple horizons and differing propagation speeds of bulk excitations in Hořava gravity. When possible, as a check on our methods and results, we use the covariant Einstein-Aether formulation of Hořava gravity, along with field redefinitions, to re-derive our results from a relativistic bulk theory.

Unraveling the Alteration History of Serpentinites and Associated Ultramafic Rocks from the Kampos HPLT Subduction Complex, Syros, Greece

NASA Astrophysics Data System (ADS)

Cooperdock, E. H. G.; Stockli, D. F.

2016-12-01

Serpentinization, hydration of peridotite, has a profound effect on fundamental tectonic and petrologic processes such as deformation of the lithosphere, bulk rheology, fluid-mobile element cycling and deep earth carbon cycling. Though numerous studies have investigated the petrology, structure and geochemistry of serpentinites, the absolute chronology of serpentinization remains elusive due to a lack of accessory minerals that can be dated using established geochronological techniques. Magnetite forms as a common secondary mineral in serpentinites from the fluid-induced breakdown reaction of primary peridotite minerals. Magnetite (U-Th)/He chronometry provides the potential to directly date the cooling of exhumed ultramafic bodies and the low-temperature fluid alteration of serpentinites. We present the first application of magnetite (U-Th)/He chronometry to date stages of alteration in ultramafic rocks from the Kampos mélange belt, a high-pressure low-temperature (HP-LT) subduction complex that experienced exhumation in the Miocene on the island of Syros, Greece. Two generations of magnetite are distinguishable by grain size, magnetite trace element geochemistry and (U-Th)/He age. Large magnetite grains (mm) from a chlorite schist and a serpentinite schist have distinct geochemical signatures indicative of formation during blackwall-related fluid alteration and record Mid-Miocene exhumation-related cooling ages, similar to zircon (U-Th)/He ages from northern Syros. Smaller grains (µm) from the serpentinite schist lack blackwall-related fluid signatures and record post-exhumation mineral formation associated with widespread high-angle Pliocene normal faulting. These results reveal evidence for multiple episodes of fluid-rock alteration, which has implications for the cooling history and local geochemical exchanges of this HP-LT terrane. Given the fundamental impact of serpentinizaton on a vast array of tectonic, petrological, and geochemical processes, the ability to differentiate and date these alteration events can be used to address significant questions related to serpentinization in exhumed subduction complexes, continental margins, or obducted ophiolites.

Dynamic behavior of microscale particles controlled by standing bulk acoustic waves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Greenhall, J.; Raeymaekers, B., E-mail: bart.raeymaekers@utah.edu; Guevara Vasquez, F.

2014-10-06

We analyze the dynamic behavior of a spherical microparticle submerged in a fluid medium, driven to the node of a standing bulk acoustic wave created by two opposing transducers. We derive the dynamics of the fluid-particle system taking into account the acoustic radiation force and the time-dependent and time-independent drag force acting on the particle. Using this dynamic model, we characterize the transient and steady-state behavior of the fluid-particle system as a function of the particle and fluid properties and the transducer operating parameters. The results show that the settling time and percent overshoot of the particle trajectory are dependentmore » on the ratio of the acoustic radiation force and time-independent damping force. In addition, we show that the particle oscillates around the node of the standing wave with an amplitude that depends on the ratio of the time-dependent drag forces and the particle inertia.« less

The surface diffusion coefficient for an arbitrarily curved fluid-fluid interface. (I). General expression

NASA Astrophysics Data System (ADS)

M. C. Sagis, Leonard

2001-03-01

In this paper, we develop a theory for the calculation of the surface diffusion coefficient for an arbitrarily curved fluid-fluid interface. The theory is valid for systems in hydrodynamic equilibrium, with zero mass-averaged velocities in the bulk and interfacial regions. We restrict our attention to systems with isotropic bulk phases, and an interfacial region that is isotropic in the plane parallel to the dividing surface. The dividing surface is assumed to be a simple interface, without memory effects or yield stresses. We derive an expression for the surface diffusion coefficient in terms of two parameters of the interfacial region: the coefficient for plane-parallel diffusion D (AB)aa(ξ) , and the driving force d(B)I||(ξ) . This driving force is the parallel component of the driving force for diffusion in the interfacial region. We derive an expression for this driving force using the entropy balance.

Nonlinear viscosity in brane-world cosmology with a Gauss–Bonnet term

NASA Astrophysics Data System (ADS)

Debnath, P. S.; Beesham, A.; Paul, B. C.

2018-06-01

Cosmological solutions are obtained with nonlinear bulk viscous cosmological fluid in the Randall–Sundrum type II (RS) brane-world model with or without Gauss–Bonnet (GB) terms. To describe such a viscous fluid, we consider the nonlinear transport equation which may be used far from equilibrium during inflation or reheating. Cosmological models are explored for both (i) power law and (ii) exponential evolution of the early universe in the presence of an imperfect fluid described by the non-linear Israel and Stewart theory (nIS). We obtain analytic solutions and the complex field equations are also analyzed numerically to study the evolution of the universe. The stability analysis of the equilibrium points of the dynamical system associated with the evolution of the nonlinear bulk viscous fluid in the RS Brane in the presence (or absence) of a GB term are also studied.

Analysis of sources of bulk conductivity change in saturated silica sand after unbuffered TCE oxidation by permanganate.

PubMed

Hort, Ryan D; Revil, André; Munakata-Marr, Junko

2014-09-01

Time lapse resistivity surveys could potentially improve monitoring of permanganate-based in situ chemical oxidation (ISCO) of organic contaminants such as trichloroethene (TCE) by tracking changes in subsurface conductivity that result from injection of permanganate and oxidation of the contaminant. Bulk conductivity and pore fluid conductivity changes during unbuffered TCE oxidation using permanganate are examined through laboratory measurements and conductivity modeling using PHREEQC in fluid samples and porous media samples containing silica sand. In fluid samples, oxidation of one TCE molecule produces three chloride ions and one proton, resulting in an increase in fluid electrical conductivity despite the loss of two permanganate ions in the reaction. However, in saturated sand samples in which up to 8mM TCE was oxidized, at least 94% of the fluid conductivity associated with the presence of protons was removed within 3h of sand contact, most likely through protonation of silanol groups found on the surface of the sand grains. Minor conductivity effects most likely associated with pH-dependent reductive dissolution of manganese dioxide were also observed but not accounted for in pore-fluid conductivity modeling. Unaccounted conductivity effects resulted in an under-calculation of post-reaction pore fluid conductivity of 2.1% to 5.5%. Although small increases in the porous media formation factor resulting from precipitation of manganese dioxide were detected (about 3%), these increases could not be confirmed to be statistically significant. Both injection of permanganate and oxidation of TCE cause increases in bulk conductivity that would be detectable through time-lapse resistivity surveys in field conditions. Copyright © 2014 Elsevier B.V. All rights reserved.

A possible source of water in seismogenic subduction zones

NASA Astrophysics Data System (ADS)

Kameda, J.; Yamaguchi, A.; Kimura, G.; Iodp Exp. 322 Scientists

2010-12-01

Recent works on the subduction megathrusts have emphasized the mechanical function of fluids contributing dynamic slip-weakening. Basalt-hosting fault zones in on-land accretionary complexes present several textures of seismic slip under fluid-assisted condition such as implosion breccia with carbonate matrix and decrepitation of fluid inclusion. In order to clarify initiation and evolution processes of such fault zones as well as possible source of fluid in the seismogenic subduction zone, we examined a mineralogical/geochemical feature of basaltic basement recovered by IODP Exp. 322 at C0012, that is a reference site for subduction input in the Nankai Trough. A total of 10 samples (about 4 m depth interval from the basement top) were analyzed in this study. XRD analyses indicate that all of the samples contain considerable amount of smectite. The smectite does not appear as a form of interstratified phase with illite or chlorite. Preliminary chemical analyses by EDS in TEM suggest that the smectite is trioctahedral saponite with Ca as a dominant interlayer cation. To determine the saponite content quantitatively, cation exchange capacity (CEC) of bulk samples was measured. The samples show almost similar CEC of around 30 meq/100g, implying that bulk rock contains about 30 wt% of saponite, considering a general CEC of 100 meq/100g for monomineralic saponite. Such abundance of saponite might be a result from intense alteration of oceanic crust due to sea water circulation at low temperature. Previous experimental work suggests that saponite might be highly hydrated (two to three water layer hydration form) at the seismogenic P-T condition. Hence, altered upper oceanic crust is a possible water sink in the seismogenic zone. The water stored in the smectite interlayer region will be expelled via smectite to chlorite transition reaction, that might contribute to the dynamic weakening of the seimogenic plate boundary between the basement basalt and overlying accretionary prism.

Young-Laplace equation for liquid crystal interfaces

NASA Astrophysics Data System (ADS)

Rey, Alejandro D.

2000-12-01

This letter uses the classical theories of liquid crystal physics to derive the Young-Laplace equation of capillary hydrostatics for interfaces between viscous isotropic (I) fluids and nematic liquid crystals (NLC's), and establishes the existence of four energy contributions to pressure jumps across these unusual anisotropic interfaces. It is shown that in addition to the usual curvature contribution, bulk and surface gradient elasticity, elastic stress, and anchoring energy contribute to pressure differentials across the interface. The magnitude of the effect is proportional to the elastic moduli of the NLC, and to the bulk and surface orientation gradients that may be present in the nematic phase. In contrast to the planar interface between isotropic fluids, flat liquid crystal interfaces support pressure jumps if elastic stresses, bulk and surface gradient energy, and/or anchoring energies are finite.

An overview of rotating machine systems with high-temperature bulk superconductors

NASA Astrophysics Data System (ADS)

Zhou, Difan; Izumi, Mitsuru; Miki, Motohiro; Felder, Brice; Ida, Tetsuya; Kitano, Masahiro

2012-10-01

The paper contains a review of recent advancements in rotating machines with bulk high-temperature superconductors (HTS). The high critical current density of bulk HTS enables us to design rotating machines with a compact configuration in a practical scheme. The development of an axial-gap-type trapped flux synchronous rotating machine together with the systematic research works at the Tokyo University of Marine Science and Technology since 2001 are briefly introduced. Developments in bulk HTS rotating machines in other research groups are also summarized. The key issues of bulk HTS machines, including material progress of bulk HTS, in situ magnetization, and cooling together with AC loss at low-temperature operation are discussed.

Low grade metamorphism fluid circulation in a sedimentary environment thrust fault zone: properties and modeling

NASA Astrophysics Data System (ADS)

Trincal, Vincent; Lacroix, Brice; Buatier, Martine D.; Charpentier, Delphine; Labaume, Pierre; Lahfid, Abdeltif

2014-05-01

In fold-and-thrust belts, shortening is mainly accommodated by thrust faults that can constitute preferential pathways for fluid circulation. The present study focuses on the Pic de Port Vieux thrust, a second-order thrust related to major Gavarnie thrust in the Axial Zone of the Pyrenees. The fault juxtaposes lower Triassic red siltstones and sandstones in the hanging-wall and Upper Cretaceous limestone in the footwall. A dense network of synkinematic quartz-chlorite veins is present in outcrop and allows to unravel the nature of the fluid that circulated in the fault zone. The hanging wall part of fault zone comprises a core which consists of intensely foliated phyllonite; the green color of this shear zone is related to the presence of abundant newly-formed chlorite. Above, the damage zone consists of red pelites and sandstones. Both domains feature kinematic markers like S-C type shear structures associated with shear and extension quartz-chlorite veins and indicate a top to the south displacement. In the footwall, the limestone display increasing mylonitization and marmorization when getting close to the contact. In order to investigate the mineralogical and geochemical changes induced by deformation and subsequent fluid flow, sampling was conducted along a complete transect of the fault zone, from the footwall limestone to the red pelites of the hanging wall. In the footwall limestone, stable isotope and Raman spectroscopy analyzes were performed. The strain gradient is strongly correlated with a high decrease in δ18OV PDB values (from -5.5 to -14) when approaching the thrust (i.e. passing from limestone to marble) while the deformation temperatures estimated with Raman spectroscopy on carbon remain constant around 300° C. These results suggest that deformation is associated to a dynamic calcite recrystallization of carbonate in a fluid-open system. In the hanging wall, SEM observations, bulk chemical XRF analyses and mineral quantification from XRD analyses were conducted in order to compare the green phyllonites from the fault core zone with the red pelites from the damage zone. Quartz, muscovite 2M1, chlorite (clinochlore), calcite and rutile are present in all samples. Hematite occurs in the damage zone but is absent in the core zone. Synkinematic chlorites are abundant in the core and damage zones and are mainly located in veins, sometimes in association with quartz. The temperature of formation of these newly-formed chlorites is 300-350° C according to Inoue (2009) geothermometer. Mössbauer spectroscopic analyses were performed on bulk rock samples. In the damage zone, Fe3+/Fetotal vary between 0.7 and 0.8, whereas in the core zone Fe3+/Fetotal is about 0.35. This decrease in Fe3+ from the damage zone to the core zone can be related to the dissolution of hematite. In contrast, Fe3+/Fetotal in phyllosilicates is clearly related to the chlorite content relative to mica, as Fe2+ increases with chlorite content. All these data allow us to propose a model of fluid circulation in relation with the Pic de Port Vieux thrust activity. The origin of the fluid, its interactions with host-rock and the consequences on fault zone mineralizations will be discussed. Inoue, A., Meunier, A., Patrier-Mas, P., Rigault, C., Beaufort, D., Vieillard, P., 2009. Application of chemical geothermometry to low-temperature trioctahedral chlorites. Clay Clay Min. 57, 371-382.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Glynos, Emmanouil; Johnson, Kyle J.; Frieberg, Bradley

Here, the surface relaxation dynamics of supported star-shaped polymer thin films are shown to be slower than the bulk, persisting up to temperatures at least 50 degrees above the bulk glass transition temperature Tmore » $$bulk\\atop{g}$$. This behavior, exhibited by star-shaped polystyrenes (SPSs) with functionality f = 8 arms and molecular weights per arm M arm < M e (M e is the entanglement molecular weight), is shown by molecular dynamics simulations to be associated with a preferential localization of these macromolecules at the free surface. This new phenomenon is in notable contrast to that of linear chain polymer thin film systems where the surface relaxations are enhanced in relation to the bulk; this enhancement persists only for a limited temperature range above the bulk T$$bulk\\atop{g}$$. Finally, evidence of the slow surface dynamics, compared to the bulk, for temperatures well above T g and at length and time scales not associated with the glass transition has not previously been reported for polymers.« less

Free Surface Relaxations of Star-Shaped Polymer Films

DOE PAGES

Glynos, Emmanouil; Johnson, Kyle J.; Frieberg, Bradley; ...

2017-11-28

Here, the surface relaxation dynamics of supported star-shaped polymer thin films are shown to be slower than the bulk, persisting up to temperatures at least 50 degrees above the bulk glass transition temperature Tmore » $$bulk\\atop{g}$$. This behavior, exhibited by star-shaped polystyrenes (SPSs) with functionality f = 8 arms and molecular weights per arm M arm < M e (M e is the entanglement molecular weight), is shown by molecular dynamics simulations to be associated with a preferential localization of these macromolecules at the free surface. This new phenomenon is in notable contrast to that of linear chain polymer thin film systems where the surface relaxations are enhanced in relation to the bulk; this enhancement persists only for a limited temperature range above the bulk T$$bulk\\atop{g}$$. Finally, evidence of the slow surface dynamics, compared to the bulk, for temperatures well above T g and at length and time scales not associated with the glass transition has not previously been reported for polymers.« less

Transient heat transfer to a forced flow of supercritical helium at 4.2 K

NASA Astrophysics Data System (ADS)

Bloem, W. B.

The transient heat transfer coefficient of supercritical helium flowing through a rectangular copper tube with a hydraulic diameter of 5 mm has been measured. The conditions of the flow were: inlet bulk temperature of the fluid was 4.2 K pressures from 3 to 10 bar and Reynolds numbers between 1.5 × 10 4 and 2 × 10 5. The tube was heated on four sides with heat fluxes up to 9800 W m -2. From the experiments it followed that during the first tens of milliseconds the heat transfer is determined by the heat conduction in the boundary layer of the supercritical helium flow. The heat transfer coefficient can be described by h = 0.5(Π λ p C p/t) 1/2. Although the helium properties λ p and Cp are a strong function of pressure and temperature, it was remarkable that the temperature increase during a heat pulse was almost the same at different flow pressures. After analysing the data an empirical relation, h =b ṁ0.75 (t t/t) case1/n, was derived, which predicts the heat transfer coefficient at a given mass flow, ṁ, to within 10% during 0.1 s. The constants b, n and tt are related to the mass flow, ṁ, and the pressure of the fluid.

Numerical study of a confined slot impinging jet with nanofluids

PubMed Central

2011-01-01

Background Heat transfer enhancement technology concerns with the aim of developing more efficient systems to satisfy the increasing demands of many applications in the fields of automotive, aerospace, electronic and process industry. A solution for obtaining efficient cooling systems is represented by the use of confined or unconfined impinging jets. Moreover, the possibility of increasing the thermal performances of the working fluids can be taken into account, and the introduction of nanoparticles in a base fluid can be considered. Results In this article, a numerical investigation on confined impinging slot jet working with a mixture of water and Al2O3 nanoparticles is described. The flow is turbulent and a constant temperature is applied on the impinging. A single-phase model approach has been adopted. Different geometric ratios, particle volume concentrations and Reynolds number have been considered to study the behavior of the system in terms of average and local Nusselt number, convective heat transfer coefficient and required pumping power profiles, temperature fields and stream function contours. Conclusions The dimensionless stream function contours show that the intensity and size of the vortex structures depend on the confining effects, given by H/W ratio, Reynolds number and particle concentrations. Furthermore, for increasing concentrations, nanofluids realize increasing fluid bulk temperature, as a result of the elevated thermal conductivity of mixtures. The local Nusselt number profiles show the highest values at the stagnation point, and the lowest at the end of the heated plate. The average Nusselt number increases for increasing particle concentrations and Reynolds numbers; moreover, the highest values are observed for H/W = 10, and a maximum increase of 18% is detected at a concentration equal to 6%. The required pumping power as well as Reynolds number increases and particle concentrations grow, which is almost 4.8 times greater than the values calculated in the case of base fluid. List of symbols PMID:21711743

Multi-fluid MHD simulations of Europa's interaction with Jupiter's magnetosphere

NASA Astrophysics Data System (ADS)

Harris, C. D. K.; Jia, X.; Slavin, J. A.; Rubin, M.; Toth, G.

2017-12-01

Several distinct physical processes generate the interaction between Europa, the smallest of Jupiter's Galilean moons, and Jupiter's magnetosphere. The 10˚ tilt of Jupiter's dipole causes time varying magnetic fields at Europa's orbit which interact with Europa's subsurface conducting ocean to induce magnetic perturbations around the moon. Jovian plasma interacts with Europa's icy surface to sputter off neutral particles, forming a tenuous exosphere which is then ionized by impact and photo-ionization to form an ionosphere. As jovian plasma flows towards the moon, mass-loading and interaction with the ionosphere slow the flow, producing magnetic perturbations that propagate along the field lines to form an Alfvén wing current system, which connects Europa to its bright footprint in Jupiter's ionosphere. The Galileo mission has shown that the plasma interaction generates significant magnetic perturbations that obscure signatures of the induced field from the subsurface ocean. Modeling the plasma-related perturbations is critical to interpreting the magnetic signatures of Europa's induction field, and therefore to magnetic sounding of its interior, a central goal of the upcoming Europa Clipper mission. Here we model the Europa-Jupiter interaction with multi-fluid magnetohydrodynamic simulations to understand quantitatively how these physical processes affect the plasma and magnetic environment around the moon. Our model separately tracks the bulk motion of three different ion fluids (exospheric O2+, O+, and magnetospheric O+), and includes sources and losses of mass, momentum and energy to each of the ion fluids due to ionization, charge-exchange and recombination. We include calculations of the electron temperature allowing for field-aligned electron heat conduction, and Hall effects due to differential ion-electron motion. Compared to previous simulations, this multi-fluid model allows us to more accurately determine the precipitation flux of jovian plasma to Europa's surface, which has significant implications for space weathering at the moon. Including the Hall effect in our simulations enables us to determine the effects of separate ion-electron bulk motion throughout the interaction, and our simulations reveal noticeable asymmetries and small-scale features in the Alfvén wings.

Rescue Shuttle Flight Re-Entry: Controlling Astronaut Thermal Exposure

NASA Technical Reports Server (NTRS)

Gillis, David B.; Hamilton, Douglas; Ilcus, Stana; Stepaniak, Phil; Polk, J. D.; Son, Chang; Bue, Grant

2008-01-01

A rescue mission for the STS-125 Hubble Telescope Repair Mission requires reentry from space with 11 crew members aboard, exceeding past cabin thermal load experience and risking crew thermal stress potentially causing cognitive performance and physiological decrements. The space shuttle crew cabin air revitalization system (ARS) was designed to support a nominal crew complement of 4 to 7 crew and 10 persons in emergencies, all in a shirt-sleeve environment. Subsequent to the addition of full pressure suits with individual cooling units, the ARS cannot maintain a stable temperature in the crew cabin during reentry thermal loads. Bulk cabin thermal models, used for rescue mission planning and analysis of crew cabin air, were unable to accurately represent crew workstation values of air flow, carbon dioxide, and heat content for the middeck. Crew temperature models suggested significantly elevated core temperatures. Planning for an STS-400 potential rescue of seven stranded crew utilized computational fluid dynamics (CFD) models to demonstrate inhomogeneous cabin thermal properties and improve analysis compared to bulk models. In the absence of monitoring of crew temperature, heart rate, metabolic rate and incomplete engineering data on the performance of the integrated cooling garment/cooling unit (ICG/CU) at cabin temperatures above 75 degrees F, related systems & models were reevaluated and tests conducted with humans in the loop. Changes to the cabin ventilation, ICU placement, crew reentry suit-donning procedures, Orbiter Program wave-off policy and post-landing power down and crew extraction were adopted. A second CFD and core temperature model incorporated the proposed changes and confirmed satisfactory cabin temperature, improved air distribution, and estimated core temperatures within safe limits. CONCLUSIONS: These changes in equipment, in-flight and post-landing procedures, and policy were implemented for the STS-400 rescue shuttle & will be implemented in any future rescue flights from the International Space Station of stranded shuttle crews.

The standard mean-field treatment of inter-particle attraction in classical DFT is better than one might expect

NASA Astrophysics Data System (ADS)

Archer, Andrew J.; Chacko, Blesson; Evans, Robert

2017-07-01

In classical density functional theory (DFT), the part of the Helmholtz free energy functional arising from attractive inter-particle interactions is often treated in a mean-field or van der Waals approximation. On the face of it, this is a somewhat crude treatment as the resulting functional generates the simple random phase approximation (RPA) for the bulk fluid pair direct correlation function. We explain why using standard mean-field DFT to describe inhomogeneous fluid structure and thermodynamics is more accurate than one might expect based on this observation. By considering the pair correlation function g(x) and structure factor S(k) of a one-dimensional model fluid, for which exact results are available, we show that the mean-field DFT, employed within the test-particle procedure, yields results much superior to those from the RPA closure of the bulk Ornstein-Zernike equation. We argue that one should not judge the quality of a DFT based solely on the approximation it generates for the bulk pair direct correlation function.

Maglev performance of a double-layer bulk high temperature superconductor above a permanent magnet guideway

NASA Astrophysics Data System (ADS)

Deng, Z.; Wang, J.; Zheng, J.; Lin, Q.; Zhang, Y.; Wang, S.

2009-05-01

In order to improve the performance of the present high temperature superconducting (HTS) maglev vehicle system, the maglev performance of single- and double-layer bulk high temperature superconductors (HTSC) was investigated above a permanent magnet guideway (PMG). It is found that the maglev performance of a double-layer bulk HTSC is not a simple addition of each layer's levitation and guidance force. Moreover, the applied magnetic field at the position of the upper layer bulk HTSC is not completely shielded by the lower layer bulk HTSC either. 53.5% of the levitation force and 27.5% of the guidance force of the upper layer bulk HTSC are excited in the double-layer bulk HTSC arrangement in the applied field-cooling condition and working gap, bringing a corresponding improvement of 16.9% and 8.8% to the conventional single-layer bulk HTSC. The present research implies that the cost performance of upper layer bulk HTSC is a little low for the whole HTS maglev system.

Impact of temperature-velocity distribution on fusion neutron peak shape

NASA Astrophysics Data System (ADS)

Munro, David

2016-10-01

Doppler broadening of the 14 MeV DT and 2.45 MeV DD fusion neutron lines has long been our best measure of temperature in a burning plasma. At the National Ignition Facility yields are high enough and our neutron spectrometers accurate enough that we see finer details of the peak shape. For example, we can measure the shift of the peak due to bulk motion of the plasma, and we see indications of non-thermal broadening, skew, and kurtosis of the peak caused by the variations of temperature and fluid velocity during burn. We can also distinguish spectral differences among several lines of sight. This talk will review the theory of fusion neutron line shape, show examples of non-Gaussian line shapes and directional variations in NIF data, and describe detailed spectral shapes we see in radhydro implosion simulations. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Ultra-reducing conditions in average mantle peridotites and in podiform chromitites: a thermodynamic model for moissanite (SiC) formation

NASA Astrophysics Data System (ADS)

Golubkova, Anastasia; Schmidt, Max W.; Connolly, James A. D.

2016-05-01

Natural moissanite (SiC) is reported from mantle-derived samples ranging from lithospheric mantle keel diamonds to serpentinites to podiform chromitites in ophiolites related to suprasubduction zone settings (Luobusa, Dongqiao, Semail, and Ray-Iz). To simulate ultra-reducing conditions and the formation of moissanite, we compiled thermodynamic data for alloys (Fe-Si-C and Fe-Cr), carbides (Fe3C, Fe7C3, SiC), and Fe-silicides; these data were augmented by commonly used thermodynamic data for silicates and oxides. Computed phase diagram sections then constrain the P- T- fO2 conditions of SiC stability in the upper mantle. Our results demonstrate that: Moissanite only occurs at oxygen fugacities 6.5-7.5 log units below the iron-wustite buffer; moissanite and chromite cannot stably coexist; increasing pressure does not lead to the stability of this mineral pair; and silicates that coexist with moissanite have X Mg > 0.99. At upper mantle conditions, chromite reduces to Fe-Cr alloy at fO2 values 3.7-5.3 log units above the moissanite-olivine-(ortho)pyroxene-carbon (graphite or diamond) buffer (MOOC). The occurrence of SiC in chromitites and the absence of domains with almost Fe-free silicates suggest that ultra-reducing conditions allowing for SiC are confined to grain scale microenvironments. In contrast to previous ultra-high-pressure and/or temperature hypotheses for SiC origin, we postulate a low to moderate temperature mechanism, which operates via ultra-reducing fluids. In this model, graphite-/diamond-saturated moderately reducing fluids evolve in chemical isolation from the bulk rock to ultra-reducing methane-dominated fluids by sequestering H2O into hydrous phases (serpentine, brucite, phase A). Carbon isotope compositions of moissanite are consistent with an origin of such fluids from sediments originally rich in organic compounds. Findings of SiC within rocks mostly comprised by hydrous phases (serpentine + brucite) support this model. Both the hydrous phases and the limited diffusive equilibration of SiC with most minerals in the rocks indicate temperatures below 700-800 °C. Moissanite from mantle environments is hence a mineral that does not inform on pressure but on a low to moderate temperature environment involving ultra-reduced fluids. Any mineral in equilibrium with SiC could only contain traces of Fe2+ or Cr3+.

Alteration and mineralization of an oceanic forearc and the ophiolite-ocean crust analogy

USGS Publications Warehouse

Alt, J.C.; Teagle, D.A.H.; Brewer, T.; Shanks, Wayne C.; Halliday, A.

1998-01-01

Mineralogical, chemical, and isotopic (O, C, S, and Sr) analyses were performed on minerals and bulk rocks from a forearc basement section to understand alteration processes and compare with mid-ocean ridges (MOR) and ophiolites. Ocean Drilling Program Hole 786B in the Izu-Bonin forearc penetrates 103 m of sediment and 725 m into volcanic flows, breccias, and basal dikes. The rocks comprise boninites and andesites to rhyolites. Most of the section was affected by low-temperature (<100??C) seawater alteration, with temperatures increasing downward. The rocks are partly (5-25%) altered to smectite, Fe-oxyhydroxide, calcite, and phillipsite, and exhibit gains of K, Rb, and P, loss of Ca, variable changes in Si, Na, Mg, Fe, Sr, and Y, and elevated ??18O and 87Sr/86Sr. Higher temperatures (???150??C) in the basal dikes below 750 m led to more intense alteration and formation of chlorite-smectite, corrensite, albite, K-feldspar, and quartz (??chlorite). A 5 m thick hydrothermally altered and pyritized zone at 815 m in the basal dikes reacted with mixtures of seawater and hydrothermal fluids to Mg-chlorite, albite, and pyrite, and gained Mg and S and lost Si and Ca. Focused flow of hydrothermal fluids produced sericitization halos (Na-K sericite, quartz, pyrophyllite, K-feldspar, and pyrite) along quartz veins at temperatures of 200??-250??C. High 87Sr/86Sr ratios of chloritized (???0.7055) and sericitized (???0.7065) rocks indicate involvement of seawater via mixing with hydrothermal fluids. Low ??34S of sulfide (???2 to -5.5???) and sulfate (12.5???) are consistent with input of magmatic SO2 into hydrothermal fluids and disproportionation to sulfide and sulfate. Alteration processes were generally similar to those at MORs, but the arc section is more intensively altered, in part because of the presence of abundant glassy rocks and mafic phases. The increase in alteration grade below 750 m and the mineralization in the basal dikes are analogous to changes that occur near the base of the volcanic section in MOR and the Troodos ophiolite.

LABORATORY AND FIELD RESULTS LINKING HIGH BULK CONDUCTIVITIES TO THE MICROBIAL DEGRADATION OF PETROLEUM HYDROCARBONS

EPA Science Inventory

Diesel contaminated layer (i.e. 32-45 cm) was the most geoelectrically conductive and showed the peak microbial activity. Below the saturated zone microbial enhanced mineral weathering increases the ionic concentration of pore fluids, leading to increased bulk electrical conducit...

21 CFR 610.12 - Sterility.

Code of Federal Regulations, 2011 CFR

2011-04-01

... container material. (a) The test. Bulk material shall be tested separately from final container material and material from each final container shall be tested in individual test vessels as follows: (1) Using Fluid Thioglycollate Medium—(i) Bulk and final container material. The volume of product, as required by paragraph (d...

Effects of water, depth and temperature on partial melting of mantle-wedge fluxed by hydrous sediment-melt in subduction zones

NASA Astrophysics Data System (ADS)

Mallik, Ananya; Dasgupta, Rajdeep; Tsuno, Kyusei; Nelson, Jared

2016-12-01

This study investigates the partial melting of variable bulk H2O-bearing parcels of mantle-wedge hybridized by partial melt derived from subducted metapelites, at pressure-temperature (P-T) conditions applicable to the hotter core of the mantle beneath volcanic arcs. Experiments are performed on mixtures of 25% sediment-melt and 75% fertile peridotite, from 1200 to 1300 °C, at 2 and 3 GPa, with bulk H2O concentrations of 4 and 6 wt.%. Combining the results from these experiments with previous experiments containing 2 wt.% bulk H2O (Mallik et al., 2015), it is observed that all melt compositions, except those produced in the lowest bulk H2O experiments at 3 GPa, are saturated with olivine and orthopyroxene. Also, higher bulk H2O concentration increases melt fraction at the same P-T condition, and causes exhaustion of garnet, phlogopite and clinopyroxene at lower temperatures, for a given pressure. The activity coefficient of silica (ϒSiO2) for olivine-orthopyroxene saturated melt compositions (where the activity of silica, aSiO2 , is buffered by the reaction olivine + SiO2 = orthopyroxene) from this study and from mantle melting studies in the literature are calculated. In melt compositions generated at 2 GPa or shallower, with increasing H2O concentration, ϒSiO2 increases from <1 to ∼1, indicating a transition from non-ideal mixing as OH- in the melt (ϒSiO2 <1) to ideal mixing as molecular H2O (ϒSiO2 ∼1). At pressures >2 GPa, ϒSiO2 >1 at higher H2O concentrations in the melt, indicate requirement of excess energy to incorporate molecular H2O in the silicate melt structure, along with a preference for bridging species and polyhedral edge decorations. With vapor saturation in the presence of melt, ϒSiO2 decreases indicating approach towards ideal mixing of H2O in silicate melt. For similar H2O concentrations in the melt, ϒSiO2 for olivine-orthopyroxene saturated melts at 3 GPa is higher than melts at 2 GPa or shallower. This results in melts generated at 3 GPa being more silica-poor than melts at 2 GPa. Thus, variable bulk H2O and pressure of melt generation results in the partial melts from this study varying in composition from phonotephrite to basaltic andesite at 2 GPa and foidite/phonotephrite to basalt at 3 GPa, forming a spectrum of arc magmas. Modeling suggests that the trace element patterns of sediment-melt are unaffected by the process of hybridization within the hotter core of the mantle-wedge. K2O/H2O and H2O/Ce ratios of the sediment-melts are unaffected, within error, by the process of hybridization of the mantle-wedge. This implies that thermometers based on K2O/H2O and H2O/Ce ratios of arc lavas may be used to estimate slab-top temperatures when (a) sediment-melt from the slab reaches the hotter core of the mantle-wedge by focused flow (b) sediment-melt freezes in the overlying mantle at the slab-mantle interface and the hybridized package rises as a mélange diapir and partially melts at the hotter core of the mantle-wedge. Based on the results from this study and previous studies, both channelized and porous flow of sediment-melt/fluid through the sub-arc mantle can explain geochemical signatures of arc lavas under specific geodynamic scenarios of fluid/melt fluxing, hybridization, and subsequent mantle melting.

Analysis of Screen Channel LAD Bubble Point Tests in Liquid Oxygen at Elevated Temperature

NASA Technical Reports Server (NTRS)

Hartwig, Jason; McQuillen, John

2011-01-01

The purpose of this paper is to examine the key parameters that affect the bubble point pressure for screen channel Liquid Acquisition Devices in cryogenic liquid oxygen at elevated pressures and temperatures. An in depth analysis of the effect of varying temperature, pressure, and pressurization gas on bubble point is presented. Testing of a 200 x 1400 and 325 x 2300 Dutch Twill screen sample was conducted in the Cryogenics Components Lab 7 facility at the NASA Glenn Research Center in Cleveland, Ohio. Test conditions ranged from 92 to 130K and 0.138 - 1.79 MPa. Bubble point is shown to be a strong function of temperature with a secondary dependence on pressure. The pressure dependence is believed to be a function of the amount of evaporation and condensation occurring at the screen. Good agreement exists between data and theory for normally saturated liquid but the model generally under predicts the bubble point in subcooled liquid. Better correlation with the data is obtained by using the liquid temperature at the screen to determine surface tension of the fluid, as opposed to the bulk liquid temperature.

Growth and characterization of high quality UPt(3) single crystals and high resolution NMR study of superfluid He-3-B

NASA Astrophysics Data System (ADS)

Kycia, Jan Bronislaw

An ultra-high-vacuum crystal growth facility using the electron beam float zone refining method was designed and built. High quality single crystals of UPtsb3 were grown. Material quality was characterized by mass spectrometry and x-ray scattering techniques. Low temperature resistivity, AC susceptibility and specific heat measurements were also conducted. We find that the transition temperature of the material can be varied systematically by annealing. The suppression of the superconducting transition from defects is consistent with a modified Abrikosov-Gorkov formula that includes anisotropic pairing, Fermi surface anisotropy and anisotropic scattering by defects. High resolution nuclear magnetic resonance (NMR) measurements of bulk superfluid sp3He-B were performed at temperatures above 0.5 mK and at pressures from 0.3 to 28.8 bar. The resonance frequency of the bulk superfluid sp3He-B is shifted from the Larmor frequency of the normal fluid. According to the theory of Greaves the frequency shift at the superfluid transition determines a specific combination, betasb{345}, of the five fourth-order coefficients of the order parameter invariants used in the Ginzburg-Landau description of superfluid sp3He. NMR measurements were performed to determine the coefficient betasb{345} and its dependence on pressure. The results are in agreement with the theoretical calculations of Sauls and Serene that are based on strong coupling contributions which are enhanced at higher pressures.

Carbonatitic liquids and COH fluids from epidote-dolomite eclogites at 3.7 - 4.6 GPa: new perspectives on carbon transfer at subduction zones

NASA Astrophysics Data System (ADS)

Poli, S.

2013-12-01

Current knowledge on the solidus temperature for carbonate-bearing rocks suggests that carbonatitic liquids should not form in a subducted oceanic lithosphere, unless anomalous thermal relaxation occurs. For a mildly warm subduction path, COH-bearing basaltic eclogites are expected to loose all H2O component at epidote breakdown, located at approx. 2.8-3.0 GPa. Above this pressure limit, the solidus is that of a carbonated basaltic eclogite which shows a minimum temperature of 1020 °C at 4.0-4.5 GPa (Dasgupta et al. 2004). However, the oceanic crust includes a range of gabbroic rocks, altered on rifts and transforms, with large amounts of An-rich plagioclase. It has been shown that epidote disappearance with pressure depend on the normative anorthite content of the bulk composition considered (Poli et al. 2009); we therefore expect that altered gabbros might display a much wider pressure range where epidote persists, potentially affecting the solidus relationships. Notably, this applies to epidosite rocks formed in hydrothermal environments at oceanic settings, then recovered in high-pressure and ultra-high pressure terrains. New experimental data from 3.7 to 4.6 GPa, 750°C to 1000 °C are intended to unravel the effect of variable bulk and volatile compositions in model eclogites, enriched in the normative anorthite component (An37 and An45). Experiments are performed in piston cylinder and multianvil machines apparatus, using both single and, buffered, double capsule techniques. Garnet, clinopyroxene and coesite form in all syntheses. Lawsonite was found to persist at 3.7 GPa, 750 °C, with both dolomite and magnesite; at 3.8 GPa, 775-800 °C, fluid saturated conditions, epidote coexists with kyanite, dolomite and magnesite. The anhydrous assemblage garnet, omphacite, aragonite, kyanite is found at 4.2 GPa, 850 °C. At 900 °C, fluid-rich conditions, a silicate fluid/melt of granitoid composition, a carbonatitic melt and Na-carbonate are observed. Close to fluid-saturation, 3.8-4.2 GPa, 900 °C, garnet and Na-rich clinopyroxene coexist with a carbonatitic melt and dolomite. The carbonatitic melt is richer in Ca compared to dolomite, consistently with phase relationships in the model system MgCO3-FeCO3-CaCO3. In fluid-undersaturated compositions, fluid-absent melting of epidote + dolomite, enlarged in its pressure stability for An-rich gabbros, is expected to promote the generation of carbonatitic liquids. The subsolidus breakdown of epidote in the presence of carbonates at depths exceeding 120 km provides a major source of COH fluids at subarc depth. In warm subduction zones, the possibility of extracting carbonatitic liquids from a variety of gabbroic rocks and epidosites offers new scenarios on the metasomatic processes in the lithospheric wedge of subduction zones and a new mechanism for recycling carbon. Dasgupta R., Hirschmann M.M., Withers A. (2004) Earth Planet Sci Lett, 227: 73-85 Poli S., Franzolin E., Fumagalli P., Crottini A. (2009) Earth Planet Sci Lett, 278: 350-360

Thermodynamics of fluid conduction through hydrophobic channel of carbon nanotubes: The exciting force for filling of nanotubes with polar and nonpolar fluids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sahu, Pooja; Ali, Sk. M., E-mail: musharaf@barc.gov.in; Shenoy, K. T.

2015-02-21

Thermodynamic properties of the fluid in the hydrophobic pores of nanotubes are known to be different not only from the bulk phase but also from other conventional confinements. Here, we use a recently developed theoretical scheme of “two phase thermodynamic (2PT)” model to understand the driving forces inclined to spontaneous filling of carbon nanotubes (CNTs) with polar (water) and nonpolar (methane) fluids. The CNT confinement is found to be energetically favorable for both water and methane, leading to their spontaneous filling inside CNT(6,6). For both the systems, the free energy of transfer from bulk to CNT confinement is favored bymore » the increased entropy (TΔS), i.e., increased translational entropy and increased rotational entropy, which were found to be sufficiently high to conquer the unfavorable increase in enthalpy (ΔE) when they are transferred inside CNT. To the best of our knowledge, this is the first time when it has been established that the increase in translational entropy during confinement in CNT(6,6) is not unique to water-like H bonding fluid but is also observed in case of nonpolar fluids such as methane. The thermodynamic results are explained in terms of density, structural rigidity, and transport of fluid molecules inside CNT. The faster diffusion of methane over water in bulk phase is found to be reversed during the confinement in CNT(6,6). Studies reveal that though hydrogen bonding plays an important role in transport of water through CNT, but it is not the solitary driving factor, as the nonpolar fluids, which do not have any hydrogen bond formation capacity can go inside CNT and also can flow through it. The associated driving force for filling and transport of water and methane is enhanced translational and rotational entropies, which are attributed mainly by the strong correlation between confined fluid molecules and availability of more free space for rotation of molecule, i.e., lower density of fluid inside CNT due to their single file-like arrangement. To the best of our information, this is perhaps the first study of nonpolar fluid within CNT using 2PT method. Furthermore, the fast flow of polar fluid (water) over nonpolar fluid (methane) has been captured for the first time using molecular dynamic simulations.« less

An internally consistent inverse model to calculate ridge-axis hydrothermal fluxes

NASA Astrophysics Data System (ADS)

Coogan, L. A.; Dosso, S.

2010-12-01

Fluid and chemical fluxes from high-temperature, on-axis, hydrothermal systems at mid-ocean ridges have been estimated in a number of ways. These generally use simple mass balances based on either vent fluid compositions or the compositions of altered sheeted dikes. Here we combine these approaches in an internally consistent model. Seawater is assumed to enter the crust and react with the sheeted dike complex at high temperatures. Major element fluxes for both the rock and fluid are calculated from balanced stoichiometric reactions. These reactions include end-member components of the minerals plagioclase, pyroxene, amphibole, chlorite and epidote along with pure anhydrite, quartz, pyrite, pyrrhotite, titanite, magnetite, ilmenite and ulvospinel and the fluid species H2O, Mg2+, Ca2+, Fe2+, Na+, Si4+, H2S, H+ and H2. Trace element abundances (Li, B, K, Rb, Cs, Sr, Ba, U, Tl, Mn, Cu, Zn, Co, Ni, Pb and Os) and isotopic ratios (Li, B, O, Sr, Tl, Os) are calculated from simple mass balance of a fluid-rock reaction. A fraction of the Cu, Zn, Pb, Co, Ni, Os and Mn in the fluid after fluid-rock reaction is allowed to precipitate during discharge before the fluid reaches the seafloor. S-isotopes are tied to mineralogical reactions involving S-bearing phases. The free parameters in the model are the amounts of each mineralogical reaction that occurs, the amounts of the metals precipitated during discharge, and the water-to-rock ratio. These model parameters, and their uncertainties, are constrained by: (i) mineral abundances and mineral major element compositions in altered dikes from ODP Hole 504B and the Pito and Hess Deep tectonic windows (EPR crust); (ii) changes in dike bulk-rock trace element and isotopic compositions from these locations relative to fresh MORB glass compositions; and (iii) published vent fluid compositions from basalt-hosted high-temperature ridge axis hydrothermal systems. Using a numerical inversion algorithm, the probability density of different model parameter sets has been computed and thus the probability of different fluid and chemical fluxes. Most data can be fit by the model within their uncertainty. The entire dataset is best-fit with a water-to-rock mass ratio between 1.3 and 2.1 (~1 to 1.5 x10**13 kg yr-1) implying a substantial fraction of the magmatic (latent) heat available to drive the axial hydrothermal system is extracted by these systems. Many element fluxes are better constrained than in previous studies (e.g., Sr: 2 to 7 x10**8 moles yr-1; Ca: 2 to 7 x10**11 moles yr-1). Future developments will use experimental data to further constrain the model.

Accurate bulk density determination of irregularly shaped translucent and opaque aerogels

NASA Astrophysics Data System (ADS)

Petkov, M. P.; Jones, S. M.

2016-05-01

We present a volumetric method for accurate determination of bulk density of aerogels, calculated from extrapolated weight of the dry pure solid and volume estimates based on the Archimedes' principle of volume displacement, using packed 100 μm-sized monodispersed glass spheres as a "quasi-fluid" media. Hard particle packing theory is invoked to demonstrate the reproducibility of the apparent density of the quasi-fluid. Accuracy rivaling that of the refractive index method is demonstrated for both translucent and opaque aerogels with different absorptive properties, as well as for aerogels with regular and irregular shapes.

Comparative study of magnetic ordering in bulk and nanoparticles of Sm0.65Ca0.35MnO3: Magnetization and electron magnetic resonance measurements

NASA Astrophysics Data System (ADS)

Goveas, Lora Rita; Anuradha, K. N.; Bhagyashree, K. S.; Bhat, S. V.

2015-05-01

To explore the effect of size reduction to nanoscale on the hole doped Sm0.65Ca0.35MnO3 compound, dc magnetic measurements and electron magnetic resonance (EMR) were done on bulk and nanoparticle samples in the temperature range 10 ≤ T ≤ 300 K. Magnetization measurement showed that the bulk sample undergoes a charge ordering transition at 240 K and shows a mixed magnetic phase at low temperature. However, the nanosample underwent a ferromagnetic transition at 75 K, and the charge ordered state was destabilized on size reduction down to nanoscale. The low-temperature ferromagnetic component is found to be enhanced in nanoparticles as compared to their bulk counterpart. Interestingly around room temperature, bulk particles show higher magnetization where as at low temperature nanoparticles show higher magnetization. Ferromagnetism in the bulk is due to super exchange where as ferromagnetism in nanoparticles is due to uncompensated spins of the surface layer. Temperature variation of EMR parameters correlates well with the results of magnetic measurements. The magnetic behaviour of the nanoparticles is understood in terms of the core shell scenario.

Bulk viscosity of molecular fluids

NASA Astrophysics Data System (ADS)

Jaeger, Frederike; Matar, Omar K.; Müller, Erich A.

2018-05-01

The bulk viscosity of molecular models of gases and liquids is determined by molecular simulations as a combination of a dilute gas contribution, arising due to the relaxation of internal degrees of freedom, and a configurational contribution, due to the presence of intermolecular interactions. The dilute gas contribution is evaluated using experimental data for the relaxation times of vibrational and rotational degrees of freedom. The configurational part is calculated using Green-Kubo relations for the fluctuations of the pressure tensor obtained from equilibrium microcanonical molecular dynamics simulations. As a benchmark, the Lennard-Jones fluid is studied. Both atomistic and coarse-grained force fields for water, CO2, and n-decane are considered and tested for their accuracy, and where possible, compared to experimental data. The dilute gas contribution to the bulk viscosity is seen to be significant only in the cases when intramolecular relaxation times are in the μs range, and for low vibrational wave numbers (<1000 cm-1); This explains the abnormally high values of bulk viscosity reported for CO2. In all other cases studied, the dilute gas contribution is negligible and the configurational contribution dominates the overall behavior. In particular, the configurational term is responsible for the enhancement of the bulk viscosity near the critical point.

Effects of solid/liquid phase fractionation on pH and aqueous species molality in subduction zone fluids

NASA Astrophysics Data System (ADS)

Zhong, X.; Galvez, M. E.

2017-12-01

Metamorphic fluids are a crucial ingredient of geodynamic evolution, i.e. heat transfer, rock mechanics and metamorphic/metasomatic reactions. During crustal evolution at elevated P and T, rock forming components can be effectively fractionated from the reactive rock system by at least two processes: 1. extraction from porous rocks by liquid phases such as solute-bearing (e.g. Na+, Mg2+) aqueous fluids or partial melts. 2. isolation from effective bulk rock composition due to slow intragranular diffusion in high-P refractory phases such as garnet. The effect of phase fractionation (garnet, partial melt and aqueous species) on fluid - rock composition and properties remain unclear, mainly due to a high demand in quantitative computations of the thermodynamic interactions between rocks and fluids over a wide P-T range. To investigate this problem, we build our work on an approach initially introduced by Galvez et al., (2015) with new functionalities added in a MATLAB code (Rubisco). The fluxes of fractionated components in fluid, melt and garnet are monitored along a typical prograde P-T path for a model crustal pelite. Some preliminary results suggest a marginal effect of fractionated aqueous species on fluid and rock properties (e.g. pH, composition), but the corresponding fluxes are significant in the context of mantle wedge metasomatism. Our work provides insight into the role of high-P phase fractionation on mass redistribution between the surface and deep Earth in subduction zones. Existing limitations relevant to our liquid/mineral speciation/fractionation model will be discussed as well. ReferencesGalvez, M.E., Manning, C.E., Connolly, J.A.D., Rumble, D., 2015. The solubility of rocks in metamorphic fluids: A model for rock-dominated conditions to upper mantle pressure and temperature. Earth Planet. Sci. Lett. 430, 486-498.

Fast 2D fluid-analytical simulation of ion energy distributions and electromagnetic effects in multi-frequency capacitive discharges

NASA Astrophysics Data System (ADS)

Kawamura, E.; Lieberman, M. A.; Graves, D. B.

2014-12-01

A fast 2D axisymmetric fluid-analytical plasma reactor model using the finite elements simulation tool COMSOL is interfaced with a 1D particle-in-cell (PIC) code to study ion energy distributions (IEDs) in multi-frequency capacitive argon discharges. A bulk fluid plasma model, which solves the time-dependent plasma fluid equations for the ion continuity and electron energy balance, is coupled with an analytical sheath model, which solves for the sheath parameters. The time-independent Helmholtz equation is used to solve for the fields and a gas flow model solves for the steady-state pressure, temperature and velocity of the neutrals. The results of the fluid-analytical model are used as inputs to a PIC simulation of the sheath region of the discharge to obtain the IEDs at the target electrode. Each 2D fluid-analytical-PIC simulation on a moderate 2.2 GHz CPU workstation with 8 GB of memory took about 15-20 min. The multi-frequency 2D fluid-analytical model was compared to 1D PIC simulations of a symmetric parallel-plate discharge, showing good agreement. We also conducted fluid-analytical simulations of a multi-frequency argon capacitively coupled plasma (CCP) with a typical asymmetric reactor geometry at 2/60/162 MHz. The low frequency 2 MHz power controlled the sheath width and sheath voltage while the high frequencies controlled the plasma production. A standing wave was observable at the highest frequency of 162 MHz. We noticed that adding 2 MHz power to a 60 MHz discharge or 162 MHz to a dual frequency 2 MHz/60 MHz discharge can enhance the plasma uniformity. We found that multiple frequencies were not only useful for controlling IEDs but also plasma uniformity in CCP reactors.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Das, Chandan K.; Singh, Jayant K., E-mail: jayantks@iitk.ac.in

The solid-liquid coexistence of a Lennard-Jones fluid confined in slit pores of variable pore size, H, is studied using molecular dynamics simulations. Three-stage pseudo-supercritical transformation path of Grochola [J. Chem. Phys. 120(5), 2122 (2004)] and multiple histogram reweighting are employed for the confined system, for various pore sizes ranging from 20 to 5 molecular diameters, to compute the solid-liquid coexistence. The Gibbs free energy difference is evaluated using thermodynamic integration method by connecting solid-liquid phases under confinement via one or more intermediate states without any first order phase transition among them. Thermodynamic melting temperature is found to oscillate with wallmore » separation, which is in agreement with the behavior seen for kinetic melting temperature evaluated in an earlier study. However, thermodynamic melting temperature for almost all wall separations is higher than the bulk case, which is contrary to the behavior seen for the kinetic melting temperature. The oscillation founds to decay at around H = 12, and beyond that pore size dependency of the shift in melting point is well represented by the Gibbs-Thompson equation.« less

Fermionic halos at finite temperature in AdS/CFT

NASA Astrophysics Data System (ADS)

Argüelles, Carlos R.; Grandi, Nicolás E.

2018-05-01

We explore the gravitational backreaction of a system consisting in a very large number of elementary fermions at finite temperature, in asymptotically AdS space. We work in the hydrodynamic approximation, and solve the Tolman-Oppenheimer-Volkoff equations with a perfect fluid whose equation of state takes into account both the relativistic effects of the fermionic constituents, as well as its finite temperature effects. We find a novel dense core-diluted halo structure for the density profiles in the AdS bulk, similarly as recently reported in flat space, for the case of astrophysical dark matter halos in galaxies. We further study the critical equilibrium configurations above which the core undergoes gravitational collapse towards a massive black hole, and calculate the corresponding critical central temperatures, for two qualitatively different central regimes of the fermions: the diluted-Fermi case, and the degenerate case. As a probe for the dual CFT, we construct the holographic two-point correlator of a scalar operator with large conformal dimension in the worldline limit, and briefly discuss on the boundary CFT effects at the critical points.

Effects of small-scale chemical reactions between supercritical CO2 and arkosic sandstone on large-scale permeability fields: An experimental study with implications for geologic carbon sequestration

NASA Astrophysics Data System (ADS)

Luhmann, A. J.; Ding, K.; Saar, M. O.; Seyfried, W. E.

2011-12-01

During geologic carbon sequestration, small, pore-scale changes in mineralogy due to dissolution and precipitation reactions can modify bulk porosity. Porosity/permeability relationships are then typically used to infer large-scale permeability field changes. However, these relationships have limited use because they do not account for changes in pore geometry. Therefore, in connection with a DOE sponsored program, involving CO2 sequestration with geothermal energy usage, we constructed a novel hydrothermal flow system that allows simultaneous determination of changes in fluid chemistry and associated changes in permeability at elevated temperatures and high CO2 pressure. Initial experiments were conducted with an arkosic sandstone core of the Eau Claire Formation from southeastern Minnesota. The core was disaggregated and then wet sieved to yield a grain size distribution of 90-120 μm that was used to fill the Teflon sleeve held within the stainless steel pressure vessel. Initial water chemistry consisted of CO2 dissolved in deionized water. Outlet pressure was set to 11 MPa, and confinement pressure was 20 MPa. Flow rates produced inlet pressures between these two extremes, allowing CO2 solubility up to 1.1 mol/kg water. Rates of fluid flow ranged from 0.04 to 1.5 mL/min at a temperature of 21°C over the course of 33 days. Based on these data, the in-situ permeability of ~1E-14 to 9E-14 m2 for the arkosic sandstone was calculated. The reaction cell temperature was then increased to 50°C, and eventually 100°C. Each temperature step was associated with a sharp decrease in permeability, such that at 100°C the permeability had decreased by approximately three orders of magnitude from the starting condition. Fluid samples indicate release of dissolved Na, Ca, Mg, K, Al, SiO2, and Cl from minerals in the core, suggesting dissolution of primary mineral components. Charge balance constraints indicate a pH of approximately 4.2 at the highest temperature run condition, considerably higher than would exist in a simple water-CO2 fluid, underscoring the effectiveness of mineral dissolution/precipitation reactions in buffering pH. Distribution of aqueous species calculations suggests possible secondary phases may include illite, muscovite, kaolinite, and quartz. We speculate that mineral precipitation occurs at the fluid-mineral interface. Thus, potentially small changes in mineralogy may produce a significant change in rock permeability.

Phenomenological constraints on the bulk viscosity of QCD

NASA Astrophysics Data System (ADS)

Paquet, Jean-François; Shen, Chun; Denicol, Gabriel; Jeon, Sangyong; Gale, Charles

2017-11-01

While small at very high temperature, the bulk viscosity of Quantum Chromodynamics is expected to grow in the confinement region. Although its precise magnitude and temperature-dependence in the cross-over region is not fully understood, recent theoretical and phenomenological studies provided evidence that the bulk viscosity can be sufficiently large to have measurable consequences on the evolution of the quark-gluon plasma. In this work, a Bayesian statistical analysis is used to establish probabilistic constraints on the temperature-dependence of bulk viscosity using hadronic measurements from RHIC and LHC.

Some heat transfer and hydrodynamic problems associated with superconducting cables (SPTL)

NASA Technical Reports Server (NTRS)

Hendricks, R. C.; Daney, D. E.; Yeroshenko, V. M.; Kuznetsov, Y. V.; Shevckenko, O. A.

1978-01-01

To study some effects of thermogravitation on (CIIK-SPTL) systems, a heated tube experiment was set up at Krzhizhanovsky Power Engineering Institute Moscow, U.S.S.R. Heat transfer data were taken with fluid helium flowing through a 2.85 m, 19 mm diameter uniformly heated horizontal tube. Temperatures were measured on the top and bottom of the tube at six axial locations with three other circumferential measurements made at (X/L) =57. Typical temperature profiles show significant variations both axially and circumferentially. The data are grouped using reduced Nusselt number (NuR) and the bulk expansion parameter for each axial location. The average data for 0.26 less than or equal to X/L less than or equal to 0.76 follow a power law relation with the average expansion parameter. System instabilities are noted and discussed. Future work including heat transfer in coaxial cylinders is discussed.

A network model for characterizing brine channels in sea ice

NASA Astrophysics Data System (ADS)

Lieblappen, Ross M.; Kumar, Deip D.; Pauls, Scott D.; Obbard, Rachel W.

2018-03-01

The brine pore space in sea ice can form complex connected structures whose geometry is critical in the governance of important physical transport processes between the ocean, sea ice, and surface. Recent advances in three-dimensional imaging using X-ray micro-computed tomography have enabled the visualization and quantification of the brine network morphology and variability. Using imaging of first-year sea ice samples at in situ temperatures, we create a new mathematical network model to characterize the topology and connectivity of the brine channels. This model provides a statistical framework where we can characterize the pore networks via two parameters, depth and temperature, for use in dynamical sea ice models. Our approach advances the quantification of brine connectivity in sea ice, which can help investigations of bulk physical properties, such as fluid permeability, that are key in both global and regional sea ice models.

Effects of causality on the fluidity and viscous horizon of quark-gluon plasma

NASA Astrophysics Data System (ADS)

Rahaman, Mahfuzur; Alam, Jan-e.

2018-05-01

The second-order Israel-Stewart-M u ̈ller relativistic hydrodynamics was applied to study the effects of causality on the acoustic oscillation in relativistic fluid. Causal dispersion relations have been derived with nonvanishing shear viscosity, bulk viscosity, and thermal conductivity at nonzero temperature and baryonic chemical potential. These relations have been used to investigate the fluidity of quark-gluon plasma (QGP) at finite temperature (T ). Results of the first-order dissipative hydrodynamics have been obtained as a limiting case of the second-order theory. The effects of the causality on the fluidity near the transition point and on the viscous horizon are found to be significant. We observe that the inclusion of causality increases the value of fluidity measure of QGP near Tc and hence makes the flow strenuous. It was also shown that the inclusion of the large magnetic field in the causal hydrodynamics alters the fluidity of QGP.

Numerical modeling of temperature and species distributions in hydrocarbon reservoirs

NASA Astrophysics Data System (ADS)

Bolton, Edward W.; Firoozabadi, Abbas

2014-01-01

We examine bulk fluid motion and diffusion of multicomponent hydrocarbon species in porous media in the context of nonequilibrium thermodynamics, with particular focus on the phenomenology induced by horizontal thermal gradients at the upper and lower horizontal boundaries. The problem is formulated with respect to the barycentric (mass-averaged) frame of reference. Thermally induced convection, with fully time-dependent temperature distributions, can lead to nearly constant hydrocarbon composition, with minor unmixing due to thermal gradients near the horizontal boundaries. Alternately, the composition can be vertically segregated due to gravitational effects. Independent and essentially steady solutions have been found to depend on how the compositions are initialized in space and may have implications for reservoir history. We also examine injection (to represent filling) and extraction (to represent leakage) of hydrocarbons at independent points and find a large distortion of the gas-oil contact for low permeability.

Models for viscosity and shear localization in bubble-rich magmas

NASA Astrophysics Data System (ADS)

Vona, Alessandro; Ryan, Amy G.; Russell, James K.; Romano, Claudia

2016-09-01

Bubble content influences magma rheology and, thus, styles of volcanic eruption. Increasing magma vesicularity affects the bulk viscosity of the bubble-melt suspension and has the potential to promote non-Newtonian behavior in the form of shear localization or brittle failure. Here, we present a series of high temperature uniaxial deformation experiments designed to investigate the effect of bubbles on the magma bulk viscosity. The starting materials are cores of natural rhyolitic obsidian synthesized to have variable vesicularity (ϕ = 0- 66%). The foamed cores were deformed isothermally (T = 750 °C) at atmospheric conditions using a high-temperature uniaxial press under constant displacement rates (strain rates between 0.5- 1 ×10-4 s-1) and to total strains of 10-40%. The viscosity of the bubble-free melt (η0) was measured by micropenetration and parallel plate methods to establish a baseline for experiments on the vesicle rich cores. At the experimental conditions, rising vesicle content produces a marked decrease in bulk viscosity that is best described by a two-parameter empirical equation: log10 ⁡ηBulk =log10 ⁡η0 - 1.47[ ϕ / (1 - ϕ) ] 0.48. Our parameterization of the bubble-melt rheology is combined with Maxwell relaxation theory to map the potential onset of non-Newtonian behavior (shear localization) in magmas as a function of melt viscosity, vesicularity, and strain rate. For low degrees of strain (i.e. as in our study), the rheological properties of vesicular magmas under different flow types (pure vs. simple shear) are indistinguishable. For high strain or strain rates where simple and pure shear viscosity values may diverge, our model represents a maximum boundary condition. Vesicular magmas can behave as non-Newtonian fluids at lower strain rates than unvesiculated melts, thereby, promoting shear localization and (explosive or non-explosive) magma fragmentation. The extent of shear localization in magma influences outgassing efficiency, thereby, affecting magma ascent and the potential for explosivity.

Advances in cryogenic engineering. Volume 27 - Proceedings of the Cryogenic Engineering Conference, San Diego, CA, August 11-14, 1981

NASA Astrophysics Data System (ADS)

Fast, R. W.

Applications of superconductivity are considered, taking into account MHD and fusion, generators, transformers, transmission lines, magnets for physics, cryogenic techniques, electrtronics, and aspects of magnet stability. Advances related to heat transfer in He I are discussed along with subjects related to theat transfer in He II, refrigeration of superconducting systems, refrigeration and liquefaction, dilution and magnetic refrigerators, refrigerators for space applications, mass transfer and flow phenomena, and the properties of fluids. Developments related to cryogenic applications are also explored, giving attention to bulk storage and transfer of cryogenic fluids, liquefied natural gas operations, space science and technology, and cryopumping. Topics related to cryogenic instrumentation and controls include the production and use of high grade silicon diode temperature sensors, the choice of strain gages for use in a large superconducting alternator, microprocessor control of cryogenic pressure, and instrumentation, data acquisition and reduction for a large spaceborne helium dewar. For individual items see A83-43221 to A83-43250

Carbide-metal assemblages in a sample returned from asteroid 25143 Itokawa: Evidence for methane-rich fluids during metamorphism

NASA Astrophysics Data System (ADS)

Harries, Dennis; Langenhorst, Falko

2018-02-01

We found that the particle RA-QD02-0115 returned by the Hayabusa spacecraft from near-Earth asteroid 25143 Itokawa contains the iron carbide haxonite (Fe21.9-22.7Co0.2-0.3Ni0.2-0.8)C6 and several Fe,Ni alloys, including multi-domain tetrataenite and spinodally decomposed taenite. Ellipsoidal to nearly spherical voids occur throughout the particle and suggest the presence of a fluid phase during textural and chemical equilibration of the host rock within the parent asteroid of 25143 Itokawa. The calculated solubility of carbon in Fe,Ni metal indicates that the carbide formed at temperatures larger than 600 °C during thermal metamorphism of the LL-chondritic mineral assemblage. Haxonite formed metastably with respect to graphite and cohenite, probably due to its high degree of lattice match with neighboring taenite, a low cooling rate at peak metamorphic temperatures, and the hindered nucleation of graphite. Thermodynamic equilibrium calculations indicate that the fluid present was dry (H2O-poor) and dominated by methane. The reactive fluid most plausibly had an atomic H/C ratio of 4-5 and was derived from the reduction of macromolecular, insoluble organic matter (IOM) that initially co-accreted with water ice. The initial presence of water is a necessary assumption to provide sufficient hydrogen for the formation of methane from hydrolyzed IOM. Metallic iron was in turn partially oxidized and incorporated into the ferromagnesian silicates during the high-temperature stage of metamorphism. An exemplary bulk reaction from unequilibrated material on the left to an equilibrated assemblage on the right may be written as: 330 CH0.8O0.2(IOM) + 500 H2O(ice/g) + 681 Fe(in alloy) + 566 FeSiO3(in Opx) → 300 CH4(g) + 32 H2(g) + 5 Fe23C6(in Hx) + 566 Fe2SiO4(in Ol) (Opx = orthopyroxene, Hx = haxonite, Ol = olivine, g = fluid species). The best estimate of the fluid/rock ratio in the region of the LL parent body where RA-QD02-0115 formed is about 3 × 10-3 and corresponds to an initial ice/rock ratio of about 7 × 10-3 (both by mass).

Reequilibration of fluid inclusions in low-temperature calcium-carbonate cement

NASA Astrophysics Data System (ADS)

Goldstein, Robert H.

1986-09-01

Calcium-carbonate cements precipitated in low-temperature, near-surface, vadose environments contain fluid inclusions of variable vapor-to-liquid ratios that yield variable homogenization temperatures. Cements precipitated in low-temperature, phreatic environments contain one-phase, all-liquid fluid inclusions. Neomorphism of unstable calcium-carbonate phases may cause reequilibration of fluid inclusions. Stable calcium-carbonate cements of low-temperature origin, which have been deeply buried, contain fluid inclusions of variable homogenization temperature and variable salt composition. Most inclusion fluids are not representative of the fluids present during cement growth and are more indicative of burial pore fluids. Therefore, low-temperature fluid inclusions probably reequilibrate with burial fluids during progressive burial. Reequilibration is likely caused by high internal pressures in inclusions which result in hydrofracturing. The resulting fluid-inclusion population could contain a nearly complete record of burial fluids in which a particular rock has been bathed. *Present address: Department of Geology, University of Kansas, Lawrence, Kansas 66045

Remobilizing the Interfaces of Thermocapillary Driven Bubbles Retarded by the Adsorption of a Surfactant Impurity on the Bubble Surface

NASA Technical Reports Server (NTRS)

Palaparthi, Ravi; Maldarelli, Charles; Papageorgiou, Dimitri; Singh, Bhim S. (Technical Monitor)

2000-01-01

Thermocapillary migration is a method for moving bubbles in space in the absence of buoyancy. A temperature gradient is applied to the continuous phase in which a bubble is situated, and the applied gradient impressed on the bubble surface causes one pole of the drop to be cooler than the opposite pole. As the surface tension is a decreasing function of temperature, the cooler pole pulls at the warmer pole, creating a flow which propels the bubble in the direction of the warmer fluid. A major impediment to the practical use of thermocapillarity to direct the movement of bubbles in space is the fact that surfactant impurities which are unavoidably present in the continuous phase can significantly reduce the migration velocity. A surfactant impurity adsorbed onto the bubble interface is swept to the trailing end of the bubble. When bulk concentrations are low (which is the case with an impurity), diffusion of surfactant to the front end is slow relative to convection, and surfactant collects at the back end of the bubble. Collection at the back lowers the surface tension relative to the front end setting up a reverse tension gradient. For buoyancy driven bubble motions in the absence of a thermocapillarity, the tension gradient opposes the surface flow, and reduces the surface and terminal velocities (the interface becomes more solid-like). When thermocapillary forces are present, the reverse tension gradient set up by the surfactant accumulation reduces the temperature tension gradient, and decreases to near zero the thermocapillary velocity. The objective of our research is to develop a method for enhancing the thermocapillary migration of bubbles which have been retarded by the adsorption onto the bubble surface of a surfactant impurity, Our remobilization theory proposes to use surfactant molecules which kinetically rapidly exchange between the bulk and the surface and are at high bulk concentrations. Because the remobilizing surfactant is present at much higher concentrations than the impurity, it adsorbs to the bubble much faster than the impurity when the bubble is formed, and thereby prevents the impurity from adsorbing onto the surface. In addition the rapid kinetic exchange and high bulk concentration maintain a saturated surface with a uniform surface concentrations. This prevents retarding surface tension gradients and keeps the velocity high. In our first report last year, we detailed experimental results which verified the theory of remobilization in ground based experiments in which the steady velocity of rising bubbles was measured in a continuous phase consisting of a glycerol/water mixture containing a polyethylene glycol surfactant C12E6 (CH3(CH2)11(OCH2CH2)6OH). In our report this year, we detail our efforts to describe theoretically the remobilization observed. We construct a model in which a bubble rises steadily by buoyancy in a continuous (Newtonian) viscous fluid containing surfactant with a uniform far field bulk concentration. We account for the effects of inertia as well as viscosity in the flow in the continuous phase caused by the bubble motion (order one Reynolds number), and we assume that the bubble shape remains spherical (viscous and inertial forces are smaller than capillary forces, i e. small Weber and capillary numbers). The surfactant distribution is calculated by solving the mass transfer equations including convection and diffusion in the bulk, and finite kinetic exchange the bulk and the surface. Convective effects dominate diffusive mass transfer in the bulk of the liquid (high Peclet numbers) except in a thin boundary layer near the surface. A finite volume method is used to numerically solve the hydrodynamic and mass transfer equations on a staggered grid which accounts specifically for the thin boundary layer. We present the results of the nondimensional drag as a function of the bulk concentration of surfactant for different rates of kinetic exchange, from which we develop criteria for the concentration necessary to develop a prescribed degree of remobilization. The criteria compare favorably with the experimental results.

Green Tea Leaves Extract: Microencapsulation, Physicochemical and Storage Stability Study.

PubMed

Zokti, James A; Sham Baharin, Badlishah; Mohammed, Abdulkarim Sabo; Abas, Faridah

2016-07-26

Green tea polyphenols have been reported to possess many biological properties. Despite the many potential benefits of green tea extracts, their sensitivity to high temperature, pH and oxygen is a major disadvantage hindering their effective utilization in the food industry. Green tea leaves from the Cameron Highlands Malaysia were extracted using supercritical fluid extraction (SFE). To improve the stability, green tea extracts were encapsulated by spray-drying using different carrier materials including maltodextrin (MD), gum arabic (GA) and chitosan (CTS) and their combinations at different ratios. Encapsulation efficiency, total phenolic content and antioxidant capacity were determined and were found to be in the range of 71.41%-88.04%, 19.32-24.90 (g GAE/100 g), and 29.52%-38.05% respectively. Further analysis of moisture content, water activity, hygroscopicity, bulk density and mean particles size distribution of the microparticles were carried out and the results ranged from; 2.31%-5.11%, 0.28-0.36, 3.22%-4.71%, 0.22-0.28 g/cm³ and 40.43-225.64 µm respectively. The ability of the microparticles to swell in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) was determined as 142.00%-188.63% and 207.55%-231.77%, respectively. Release of catechin polyphenol from microparticles in SIF was higher comparable to that of SGF. Storage stability of encapsulated catechin extracts under different temperature conditions was remarkably improved compared to non-encapsulated extract powder. This study showed that total catechin, total phenolic content (TPC) and antioxidant activity did not decrease significantly (p ≥ 0.05) under 4 °C storage conditions. The half-life study results were in the range of 35-60, 34-65 and 231-288 weeks at storage temperatures of 40 °C, 25 °C and 4 °C respectively, therefore, for improved shelf-life stability we recommend that microparticles should be stored at temperatures below 25 °C.

Synthesis and Manipulation of Semiconductor Nanocrystals inMicrofluidic Reactors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chan, Emory Ming-Yue

2006-01-01

Microfluidic reactors are investigated as a mechanism tocontrol the growth of semiconductor nanocrystals and characterize thestructural evolution of colloidal quantum dots. Due to their shortdiffusion lengths, low thermal masses, and predictable fluid dynamics,microfluidic devices can be used to quickly and reproducibly alterreaction conditions such as concentration, temperature, and reactiontime, while allowing for rapid reagent mixing and productcharacterization. These features are particularly useful for colloidalnanocrystal reactions, which scale poorly and are difficult to controland characterize in bulk fluids. To demonstrate the capabilities ofnanoparticle microreactors, a size series of spherical CdSe nanocrystalswas synthesized at high temperature in a continuous-flow, microfabricatedglass reactor. Nanocrystalmore » diameters are reproducibly controlled bysystematically altering reaction parameters such as the temperature,concentration, and reaction time. Microreactors with finer control overtemperature and reagent mixing were designed to synthesize nanoparticlesof different shapes, such as rods, tetrapods, and hollow shells. The twomajor challenges observed with continuous flow reactors are thedeposition of particles on channel walls and the broad distribution ofresidence times that result from laminar flow. To alleviate theseproblems, I designed and fabricated liquid-liquid segmented flowmicroreactors in which the reaction precursors are encapsulated inflowing droplets suspended in an immiscible carrier fluid. The synthesisof CdSe nanocrystals in such microreactors exhibited reduced depositionand residence time distributions while enabling the rapid screening aseries of samples isolated in nL droplets. Microfluidic reactors werealso designed to modify the composition of existing nanocrystals andcharacterize the kinetics of such reactions. The millisecond kinetics ofthe CdSe-to-Ag 2Se nanocrystal cation exchange reaction are measured insitu with micro-X-ray Absorption Spectroscopy in silicon microreactorsspecifically designed for rapid mixing and time-resolved X-rayspectroscopy. These results demonstrate that microreactors are valuablefor controlling and characterizing a wide range of reactions in nLvolumes even when nanoscale particles, high temperatures, causticreagents, and rapid time scales are involved. These experiments providethe foundation for future microfluidic investigations into the mechanismsof nanocrystal growth, crystal phase evolution, and heterostructureassembly.« less

The Burgers/squirt-flow seismic model of the crust and mantle

NASA Astrophysics Data System (ADS)

Carcione, José M.; Poletto, Flavio; Farina, Biancamaria

2018-01-01

Part of the crust shows generally brittle behaviour while areas of high temperature and/or high pore pressure, including the mantle, may present ductile behaviour. For instance, the potential heat source of geothermal fields, overpressured formations and molten rocks. Seismic waves can be used to detect these conditions on the basis of reflection and transmission events. Basically, from the elastic-plastic point of view the seismic properties (seismic velocity, quality factor and density) depend on effective pressure and temperature. Confining and pore pressures have opposite effects on these properties, and high temperatures may induce a similar behaviour by partial melting. In order to model these effects, we consider a poro-viscoelastic model based on the Burgers mechanical element and the squirt-flow model to represent the properties of the rock frame to describe ductility in which deformation takes place by shear plastic flow, and to model local and global fluid flow effects. The Burgers element allows us to model the effects of the steady-state creep flow on the dry-rock frame. The stiffness components of the brittle and ductile media depend on stress and temperature through the shear viscosity, which is obtained by the Arrhenius equation and the octahedral stress criterion. Effective pressure effects are taken into account in the dry-rock moduli by using exponential functions whose parameters are obtained by fitting experimental data as a function of confining pressure. Since fluid effects are important, the density and bulk modulus of the saturating fluids (water at sub- and supercritical conditions) are modeled by using the equations provided by the NIST website. The squirt-flow model has a single free parameter represented by the aspect ratio of the grain contacts. The theory generalizes a preceding theory based on Gassmann (low-frequency) moduli to the more general case of the presence of local (squirt) flow and global (Biot) flow, which contribute with additional attenuation mechanisms to the wave propagation.

Numerical study of vorticity-enhanced heat transfer

NASA Astrophysics Data System (ADS)

Wang, Xiaolin; Alben, Silas

2013-11-01

Vortices produced by vibrated reeds and flapping foils can improve heat transfer efficiency in electronic hardware. Vortices enhance forced convection by boundary layer separation and thermal mixing in the bulk flow. In this work, we modeled and simulated the fluid flow and temperature in a 2-D channel flow with vortices injected at the upstream boundary. We classified four types of vortex streets depending on the Reynolds number and vortices' strengths and spacings, and studied the different vortex dynamics in each situation. We then used Lagrangian coherent structures (LCS) to study the effect of the vortices on mixing and determined how the Nusselt number and Coefficients of performance vary with flow parameters and Peclet numbers.

Active fluids at circular boundaries: swim pressure and anomalous droplet ripening.

PubMed

Jamali, Tayeb; Naji, Ali

2018-06-13

We investigate the swim pressure exerted by non-chiral and chiral active particles on convex or concave circular boundaries. Active particles are modeled as non-interacting and non-aligning self-propelled Brownian particles. The convex and concave circular boundaries are used to model a fixed inclusion immersed in an active bath and a cavity (or container) enclosing the active particles, respectively. We first present a detailed analysis of the role of convex versus concave boundary curvature and of the chirality of active particles in their spatial distribution, chirality-induced currents, and the swim pressure they exert on the bounding surfaces. The results will then be used to predict the mechanical equilibria of suspended fluid enclosures (generically referred to as 'droplets') in a bulk with active particles being present either inside the bulk fluid or within the suspended droplets. We show that, while droplets containing active particles behave in accordance with standard capillary paradigms when suspended in a normal bulk, those containing a normal fluid exhibit anomalous behaviors when suspended in an active bulk. In the latter case, the excess swim pressure results in non-monotonic dependence of the inside droplet pressure on the droplet radius; hence, revealing an anomalous regime of behavior beyond a threshold radius, in which the inside droplet pressure increases upon increasing the droplet size. Furthermore, for two interconnected droplets, mechanical equilibrium can occur also when the droplets have different sizes. We thus identify a regime of anomalous droplet ripening, where two unequal-sized droplets can reach a final state of equal size upon interconnection, in stark contrast with the standard Ostwald ripening phenomenon, implying shrinkage of the smaller droplet in favor of the larger one.

Molecular Mechanism of Pancreatic and Salivary Glands Fluid and HCO3− Secretion

PubMed Central

Lee, Min Goo; Ohana, Ehud; Park, Hyun Woo; Yang, Dongki; Muallem, Shmuel

2013-01-01

Fluid and HCO3− secretion is a vital function of all epithelia and is required for the survival of the tissue. Aberrant fluid and HCO3− secretion is associated with many epithelial diseases, such as cystic fibrosis, pancreatitis, Sjögren’s syndrome and other epithelial inflammatory and autoimmune diseases. Significant progress has been made over the last 20 years in our understanding of epithelial fluid and HCO3− secretion, in particular by secretory glands. Fluid and HCO3− secretion by secretory glands is a two step process. Acinar cells secrete isotonic fluid in which the major salt is NaCl. Subsequently, the duct modifies the volume and electrolyte composition of the fluid to absorb the Cl− and secrete HCO3−. The relative volume secreted by acinar and duct cells and modification of electrolyte composition of the secreted fluids varies among secretory glands to meet their physiological functions. In the pancreas, acinar cells secrete small amount of NaCl-rich fluid, while the duct absorbs the Cl− and secretes HCO3− and the bulk of the fluid in the pancreatic juice. Fluid secretion appears to be driven by active HCO3− secretion. In the salivary glands, acinar cells secrete the bulk of the fluid in the saliva that contains high concentrations of Na+ and Cl− and fluid secretion is mediated by active Cl− secretion. The salivary glands duct absorbs both the Na+ and Cl− and secretes K+ and HCO3−. In this review, we focus on the molecular mechanism of fluid and HCO3− secretion by the pancreas and salivary glands, to highlight the similarities of the fundamental mechanisms of acinar and duct cell functions, and point the differences to meet glands specific secretions. PMID:22298651

Compton Scattering by Static and Moving Media. Part 1; The Transfer Equation and its Moments

NASA Technical Reports Server (NTRS)

Psaltis, Dimitrios; Lamb, Frederick K.

1997-01-01

Compton scattering of photons by nonrelativistic particles is thought to play an important role in forming the radiation spectrum of many astrophysical systems. Here we derive the time-dependent photon kinetic equation that describes spontaneous and induced Compton scattering, as well as absorption and emission by static and moving media, the corresponding radiative transfer equation, and their zeroth and first angular moments, both in the system frame and in the frame comoving with the medium. We show that it is necessary to use the correct relativistic differential scattering cross section in order to obtain a photon kinetic equation that is correct to first order in Epsilon/m(sub e), T(sub e)/m(sub e), and V, where Epsilon is the photon energy, T(sub e) and m(sub e) are the electron temperature and rest mass, and V is the electron bulk velocity in units of the speed of light. We also demonstrate that the terms in the radiative transfer equation that are second order in V should usually be retained, because if the radiation energy density is sufficiently large, compared to the radiation flux, the effects of bulk Comptonization described by the terms that are second order in V can be as important as the effects described by the terms that are first order in V, even when V is small. The system- and fluid-frame equations that we derive are correct to first order in Epsilon/m(sub e). Our system-frame equations, which are correct to second order in V, may be used when V is not too large. Our fluid-frame equations, which are exact in V, may be used when V approaches 1. Both sets of equations are valid for systems of arbitrary optical depth and can therefore be used in both the free-streaming and diffusion regimes. We demonstrate that Comptonization by the electron bulk motion occurs whether or not the radiation field is isotropic or the bulk flow converges and that it is more important than thermal Comptonization if V(sup 2) is greater than 3T(sub e)/m(sub e).

Identification of dairy farm management practices associated with the presence of psychrotolerant sporeformers in bulk tank milk.

PubMed

Masiello, S N; Martin, N H; Watters, R D; Galton, D M; Schukken, Y H; Wiedmann, M; Boor, K J

2014-07-01

Some strains of sporeforming bacteria (e.g., Bacillus spp. and Paenibacillus spp.) can survive pasteurization and subsequently grow at refrigeration temperatures, causing pasteurized fluid milk spoilage. To identify farm management practices associated with different levels of sporeformers in raw milk, a bulk tank sample was obtained from and a management and herd health questionnaire was administered to 99 New York State dairy farms. Milk samples were spore pasteurized [80°C (176°F) for 12 min] and subsequently analyzed for most-probable number and for sporeformer counts on the initial day of spore pasteurization (SP), and after refrigerated storage (6°C) at 7, 14, and 21 d after SP. Management practices were analyzed for association with sporeformer counts and bulk tank somatic cell counts. Sixty-two farms had high sporeformer growth (≥3 log cfu/mL at any day after SP), with an average sporeformer count of 5.20 ± 1.41 mean log10 cfu/mL at 21 d after SP. Thirty-seven farms had low sporeformer numbers (<3 log cfu/mL for all days after SP), with an average sporeformer count of 0.75 ± 0.94 mean log10 cfu/mL at 21 d after SP. Farms with >25% of cows with dirty udders in the milking parlor were 3.15 times more likely to be in the high category than farms with ≤10% of milking cows with dirty udders. Farms with <200 cows were 3.61 times more likely to be in the high category than farms with ≥200 cows. Management practices significantly associated with increased bulk tank somatic cell count were a lack of use of the California mastitis test at freshening and >25% of cows with dirty udders observed in the milking parlor. Changes in management practices associated with cow cleanliness may directly ensure longer shelf life and higher quality of pasteurized fluid milk. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

BULK AND FILM CONTRIBUTIONS TO FLUID/FLUID INTERFACIAL AREA IN GRANULAR MEDIA. (R827116)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

Open Source Platform Application to Groundwater Characterization and Monitoring

NASA Astrophysics Data System (ADS)

Ntarlagiannis, D.; Day-Lewis, F. D.; Falzone, S.; Lane, J. W., Jr.; Slater, L. D.; Robinson, J.; Hammett, S.

2017-12-01

Groundwater characterization and monitoring commonly rely on the use of multiple point sensors and human labor. Due to the number of sensors, labor, and other resources needed, establishing and maintaining an adequate groundwater monitoring network can be both labor intensive and expensive. To improve and optimize the monitoring network design, open source software and hardware components could potentially provide the platform to control robust and efficient sensors thereby reducing costs and labor. This work presents early attempts to create a groundwater monitoring system incorporating open-source software and hardware that will control the remote operation of multiple sensors along with data management and file transfer functions. The system is built around a Raspberry PI 3, that controls multiple sensors in order to perform on-demand, continuous or `smart decision' measurements while providing flexibility to incorporate additional sensors to meet the demands of different projects. The current objective of our technology is to monitor exchange of ionic tracers between mobile and immobile porosity using a combination of fluid and bulk electrical-conductivity measurements. To meet this objective, our configuration uses four sensors (pH, specific conductance, pressure, temperature) that can monitor the fluid electrical properties of interest and guide the bulk electrical measurement. This system highlights the potential of using open source software and hardware components for earth sciences applications. The versatility of the system makes it ideal for use in a large number of applications, and the low cost allows for high resolution (spatially and temporally) monitoring.

Impedance Spectroscopy and AC Conductivity Studies of Bulk 3-Amino-7-(dimethylamino)-2-methyl-hydrochloride

NASA Astrophysics Data System (ADS)

El-Shabaan, M. M.

2018-02-01

Impedance spectroscopy and alternating-current (AC) conductivity (σ AC) studies of bulk 3-amino-7-(dimethylamino)-2-methyl-hydrochloride (neutral red, NR) have been carried out over the temperature (T) range from 303 K to 383 K and frequency (f) range from 0.5 kHz to 5 MHz. Dielectric data were analyzed using the complex impedance (Z *) and complex electric modulus (M *) for bulk NR at various temperatures. The impedance loss peaks were found to shift towards high frequencies, indicating an increase in the relaxation time (τ 0) and loss in the material, with increasing temperature. For each temperature, a single depressed semicircle was observed at high frequencies, originating from the bulk transport, and a spike in the low-frequency region, resulting from the electrode effect. Fitting of these curves yielded an equivalent circuit containing a parallel combination of a resistance R and constant-phase element (CPE) Q. The carrier transport in bulk NR is governed by the correlated barrier hopping (CBH) mechanism, some parameters of which, such as the maximum barrier height (W M), charge density (N), and hopping distance (r), were determined as functions of both temperature and frequency. The frequency dependence of σ AC at different temperatures indicated that the conduction in bulk NR is a thermally activated process. The σ AC value at different frequencies increased linearly with temperature.

Bulk viscous cosmology with causal transport theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Piattella, Oliver F.; Fabris, Júlio C.; Zimdahl, Winfried, E-mail: oliver.piattella@gmail.com, E-mail: fabris@pq.cnpq.br, E-mail: winfried.zimdahl@pq.cnpq.br

2011-05-01

We consider cosmological scenarios originating from a single imperfect fluid with bulk viscosity and apply Eckart's and both the full and the truncated Müller-Israel-Stewart's theories as descriptions of the non-equilibrium processes. Our principal objective is to investigate if the dynamical properties of Dark Matter and Dark Energy can be described by a single viscous fluid and how such description changes when a causal theory (Müller-Israel-Stewart's, both in its full and truncated forms) is taken into account instead of Eckart's non-causal one. To this purpose, we find numerical solutions for the gravitational potential and compare its behaviour with the corresponding ΛCDMmore » case. Eckart's and the full causal theory seem to be disfavoured, whereas the truncated theory leads to results similar to those of the ΛCDM model for a bulk viscous speed in the interval 10{sup −11} || cb{sup 2} ∼< 10{sup −8}.« less

First-principles melting of gallium clusters down to nine atoms: structural and electronic contributions to melting.

PubMed

Steenbergen, Krista G; Gaston, Nicola

2013-10-07

First-principles Born-Oppenheimer molecular dynamics simulations of small gallium clusters, including parallel tempering, probe the distinction between cluster and molecule in the size range of 7-12 atoms. In contrast to the larger sizes, dynamic measures of structural change at finite temperature demonstrate that Ga7 and Ga8 do not melt, suggesting a size limit to melting in gallium exists at 9 atoms. Analysis of electronic structure further supports this size limit, additionally demonstrating that a covalent nature cannot be identified for clusters larger than the gallium dimer. Ga9, Ga10 and Ga11 melt at greater-than-bulk temperatures, with no evident covalent character. As Ga12 represents the first small gallium cluster to melt at a lower-than-bulk temperature, we examine the structural properties of each cluster at finite temperature in order to probe both the origins of greater-than-bulk melting, as well as the significant differences in melting temperatures induced by a single atom addition. Size-sensitive melting temperatures can be explained by both energetic and entropic differences between the solid and liquid phases for each cluster. We show that the lower-than-bulk melting temperature of the 12-atom cluster can be attributed to persistent pair bonding, reminiscent of the pairing observed in α-gallium. This result supports the attribution of greater-than-bulk melting in gallium clusters to the anomalously low melting temperature of the bulk, due to its dimeric structure.

Experimental constraints on the relative stabilities of the two systems monazite-(Ce) - allanite-(Ce) - fluorapatite and xenotime-(Y) - (Y,HREE)-rich epidote - (Y,HREE)-rich fluorapatite, in high Ca and Na-Ca environments under P-T conditions of 200-1000 MPa and 450-750 °C

NASA Astrophysics Data System (ADS)

Budzyń, Bartosz; Harlov, Daniel E.; Kozub-Budzyń, Gabriela A.; Majka, Jarosław

2017-04-01

The relative stabilities of phases within the two systems monazite-(Ce) - fluorapatite - allanite-(Ce) and xenotime-(Y) - (Y,HREE)-rich fluorapatite - (Y,HREE)-rich epidote have been tested experimentally as a function of pressure and temperature in systems roughly replicating granitic to pelitic composition with high and moderate bulk CaO/Na2O ratios over a wide range of P-T conditions from 200 to 1000 MPa and 450 to 750 °C via four sets of experiments. These included (1) monazite-(Ce), labradorite, sanidine, biotite, muscovite, SiO2, CaF2, and 2 M Ca(OH)2; (2) monazite-(Ce), albite, sanidine, biotite, muscovite, SiO2, CaF2, Na2Si2O5, and H2O; (3) xenotime-(Y), labradorite, sanidine, biotite, muscovite, garnet, SiO2, CaF2, and 2 M Ca(OH)2; and (4) xenotime-(Y), albite, sanidine, biotite, muscovite, garnet, SiO2, CaF2, Na2Si2O5, and H2O. Monazite-(Ce) breakdown was documented in experimental sets (1) and (2). In experimental set (1), the Ca high activity (estimated bulk CaO/Na2O ratio of 13.3) promoted the formation of REE-rich epidote, allanite-(Ce), REE-rich fluorapatite, and fluorcalciobritholite at the expense of monazite-(Ce). In contrast, a bulk CaO/Na2O ratio of 1.0 in runs in set (2) prevented the formation of REE-rich epidote and allanite-(Ce). The reacted monazite-(Ce) was partially replaced by REE-rich fluorapatite-fluorcalciobritholite in all runs, REE-rich steacyite in experiments at 450 °C, 200-1000 MPa, and 550 °C, 200-600 MPa, and minor cheralite in runs at 650-750 °C, 200-1000 MPa. The experimental results support previous natural observations and thermodynamic modeling of phase equilibria, which demonstrate that an increased CaO bulk content expands the stability field of allanite-(Ce) relative to monazite-(Ce) at higher temperatures indicating that the relative stabilities of monazite-(Ce) and allanite-(Ce) depend on the bulk CaO/Na2O ratio. The experiments also provide new insights into the re-equilibration of monazite-(Ce) via fluid-aided coupled dissolution-reprecipitation, which affects the Th-U-Pb system in runs at 450 °C, 200-1000 MPa, and 550 °C, 200-600 MPa. A lack of compositional alteration in the Th, U, and Pb in monazite-(Ce) at 550 °C, 800-1000 MPa, and in experiments at 650-750 °C, 200-1000 MPa indicates the limited influence of fluid-mediated alteration on volume diffusion under high P-T conditions. Experimental sets (3) and (4) resulted in xenotime-(Y) breakdown and partial replacement by (Y,REE)-rich fluorapatite to Y-rich fluorcalciobritholite. Additionally, (Y,HREE)-rich epidote formed at the expense of xenotime-(Y) in three runs with 2 M Ca(OH)2 fluid, at 550 °C, 800 MPa; 650 °C, 800 MPa; and 650 °C, 1000 MPa similar to the experiments involving monazite-(Ce). These results confirm that replacement of xenotime-(Y) by (Y,HREE)-rich epidote is induced by a high Ca bulk content with a high CaO/Na2O ratio. These experiments demonstrate also that the relative stabilities of xenotime-(Y) and (Y,HREE)-rich epidote are strongly controlled by pressure.

Electro-osmosis of non-Newtonian fluids in porous media using lattice Poisson-Boltzmann method.

PubMed

Chen, Simeng; He, Xinting; Bertola, Volfango; Wang, Moran

2014-12-15

Electro-osmosis in porous media has many important applications in various areas such as oil and gas exploitation and biomedical detection. Very often, fluids relevant to these applications are non-Newtonian because of the shear-rate dependent viscosity. The purpose of this study was to investigate the behaviors and physical mechanism of electro-osmosis of non-Newtonian fluids in porous media. Model porous microstructures (granular, fibrous, and network) were created by a random generation-growth method. The nonlinear governing equations of electro-kinetic transport for a power-law fluid were solved by the lattice Poisson-Boltzmann method (LPBM). The model results indicate that: (i) the electro-osmosis of non-Newtonian fluids exhibits distinct nonlinear behaviors compared to that of Newtonian fluids; (ii) when the bulk ion concentration or zeta potential is high enough, shear-thinning fluids exhibit higher electro-osmotic permeability, while shear-thickening fluids lead to the higher electro-osmotic permeability for very low bulk ion concentration or zeta potential; (iii) the effect of the porous medium structure depends significantly on the constitutive parameters: for fluids with large constitutive coefficients strongly dependent on the power-law index, the network structure shows the highest electro-osmotic permeability while the granular structure exhibits the lowest permeability on the entire range of power law indices considered; when the dependence of the constitutive coefficient on the power law index is weaker, different behaviors can be observed especially in case of strong shear thinning. Copyright © 2014 Elsevier Inc. All rights reserved.

Processing of MnBi bulk magnets with enhanced energy product

DOE PAGES

Poudyal, Narayan; Liu, Xubo; Wang, Wei; ...

2016-02-23

Here, we report magnetic properties and microstructure of high energy-product MnBi bulk magnets fabricated by low-temperature ball-milling and warm compaction technique. A maximum energy product (BH) max of 8.4 MGOe and a coercivity of 6.2 kOe were obtained in the bulk MnBi magnet at room temperature. Magnetic characterization at elevated temperatures showed an increase in coercivity to 16.2 kOe while (BH) max value decreased to 6.8 MGOe at 400 K. Microstructure characterization revealed that the bulk magnets consist of oriented uniform nanoscale grains with average size about 50 nm.

Relaxation of the bulk modulus in partially molten dunite?

NASA Astrophysics Data System (ADS)

Cline, C. J.; Jackson, I.

2016-11-01

To address the possibility of melt-related bulk modulus relaxation, a forced oscillation experiment was conducted at seismic frequencies on a partially molten synthetic dunite specimen (melt fraction = 0.026) utilizing the enhanced capacity of the Australian National University attenuation apparatus to operate in both torsional and flexural oscillation modes. Shear modulus and dissipation data are consistent with those for melt-bearing olivine specimens previously tested in torsion, with a pronounced dissipation peak superimposed on high-temperature background. Flexural data exhibit a monotonic decrease in complex Young's modulus with increasing temperature under transsolidus temperatures. The observed variation of Young's modulus is well described by the relationship 1/E 1/3G, without requiring relaxation of the bulk modulus. At high homologous temperatures, when shear modulus is low, extensional and flexural oscillation measurements have little resolution of bulk modulus, and thus, only pressure oscillation measurements can definitively constrain bulk properties at these conditions.

Dynamics of yield-stress droplets: Morphology of impact craters

NASA Astrophysics Data System (ADS)

Neufeld, Jerome; Sohr, David; Ferrari, Leo; Dalziel, Stuart

2017-11-01

Yield strength can play an important role for the dynamics of droplets impacting on surfaces, whether at the industrial or planetary scale, and can capture a zoo of impact crater morphologies, from simple parabolic craters, to more complex forms with forms with, for example, multiple rings, central peaks. Here we show that the morphology of planetary impact craters can be reproduced in the laboratory using carbopol, a transparent yield-stress fluid, as both impactor and bulk fluid. Using high-speed video photography, we characterise the universal, transient initial excavation stage of impact and show the dependence of the subsequent relaxation to final crater morphology on impactor size, impact speed and yield stress. To further interrogate our laboratory impacts, we dye our impactor to map its final distribution and use particle tracking to determine the flow fields during impact and the maximal extent of the yield surface. We characterise the flow-fields induced during impact, and the maximal extent of the yield surface, by tracking particles within the bulk fluid and map the distribution of impactor and bulk by tracing the final distribution of dyed impactor. The results of laboratory impact droplets are used to infer the properties of planetary impactors, and aid in inter.

Influence of mantle viscosity structure and mineral grain size on fluid migration pathways in the mantle wedge.

NASA Astrophysics Data System (ADS)

Cerpa, N. G.; Wada, I.; Wilson, C. R.; Spiegelman, M. W.

2016-12-01

We develop a 2D numerical porous flow model that incorporates both grain size distribution and matrix compaction to explore the fluid migration (FM) pathways in the mantle wedge. Melt generation for arc volcanism is thought to be triggered by slab-derived fluids that migrate into the hot overlying mantle and reduce its melting temperature. While the narrow location of the arcs relative to the top of the slab ( 100±30 km) is a robust observation, the release of fluids is predicted to occur over a wide range of depth. Reconciling such observations and predictions remains a challenge for the geodynamic community. Fluid transport by porous flow depends on the permeability of the medium which in turn depends on fluid fraction and mineral grain size. The grain size distribution in the mantle wedge predicted by laboratory derived laws was found to be a possible mechanism to focusing of fluids beneath the arcs [Wada and Behn, 2015]. The viscous resistance of the matrix to the volumetric strain generates compaction pressure that affects fluid flow and can also focus fluids towards the arc [Wilson et al, 2014]. We thus have developed a 2D one-way coupled Darcy's-Stokes flow model (solid flow independent of fluid flow) for the mantle wedge that combines both effects. For the solid flow calculation, we use a kinematic-dynamic approach where the system is driven by the prescribed slab velocity. The solid rheology accounts for both dislocation and diffusion creep and we calculate the grain size distribution following Wada and Behn [2015]. In our fluid flow model, the permeability of the medium is grain size dependent and the matrix bulk viscosity depends on solid shear viscosity and fluid fraction. The fluid influx from the slab is imposed as a boundary condition at the base of the mantle wedge. We solve the discretized governing equations using the software package TerraFERMA. Applying a range of model parameter values, including slab age, slab dip, subduction rate, and fluid influx, we quantify the combined effects of grain size and compaction on fluid flow paths.

Measurements of unjacketed moduli of porous rock

NASA Astrophysics Data System (ADS)

Tarokh, A.; Makhnenko, R. Y.; Labuz, J.

2017-12-01

Coupling of stress and pore pressure appears in a number of applications dealing with subsurface (sedimentary) rock, including petroleum exploration and waste storage. Poroelastic analyses consider the compressibility of the solid constituents forming the rock, and often times solid bulk modulus Ks is assumed to be the same as the dominant mineral bulk modulus. In fact, there are two different parameters describing solid compressibility of a porous rock: the unjacketed bulk modulus Ks' and the unjacketed pore modulus Ks". Experimental techniques are developed to measure the two poroelastic parameters of fluid-saturated porous rock under the unjacketed condition. In an unjacketed experiment, the rock without a membrane is loaded by the fluid in a pressure vessel. The confining fluid permeates the connected pore space throughout the interior of the rock. Therefore, changes in mean stress P will produce equal changes in pore pressure p, i.e. ΔP = Δp. The test can also be performed with a jacketed rock specimen by applying equal increments of mean stress and pore pressure. The unjacketed bulk modulus, Ks', is obtained by measuring the bulk strain with resistive strain gages. The unjacketed pore modulus, Ks", the pore volume counterpart to Ks', is a measure of the change in pore pressure per unit pore volume strain under the unjacketed condition. Several indirect estimates of Ks" have been reported but limitations of these approaches do not provide an accurate value. We present direct measurements of Ks" with detailed calibration on the system volumetric response. The results indicate that for Dunnville sandstone Ks' and Ks" are equal while for Berea sandstone, a difference between the two moduli exists, which is explained by the presence of non-connected pores. The experiments also strongly suggest that both Ks' and Ks" are independent of effective stress.

Fluid absorption solar energy receiver

NASA Technical Reports Server (NTRS)

Bair, Edward J.

1993-01-01

A conventional solar dynamic system transmits solar energy to the flowing fluid of a thermodynamic cycle through structures which contain the gas and thermal energy storage material. Such a heat transfer mechanism dictates that the structure operate at a higher temperature than the fluid. This investigation reports on a fluid absorption receiver where only a part of the solar energy is transmitted to the structure. The other part is absorbed directly by the fluid. By proportioning these two heat transfer paths the energy to the structure can preheat the fluid, while the energy absorbed directly by the fluid raises the fluid to its final working temperature. The surface temperatures need not exceed the output temperature of the fluid. This makes the output temperature of the gas the maximum temperature in the system. The gas can have local maximum temperatures higher than the output working temperature. However local high temperatures are quickly equilibrated, and since the gas does not emit radiation, local high temperatures do not result in a radiative heat loss. Thermal radiation, thermal conductivity, and heat exchange with the gas all help equilibrate the surface temperature.

Intravenous fluid temperature management by infrared thermometer.

PubMed

Lapostolle, Frédéric; Catineau, Jean; Le Toumelin, Philippe; Proust, Clément; Garrigue, Bruno; Galinski, Michel; Adnet, Frédéric

2006-03-01

The management of intravenous (IV) fluid temperature is a daily challenge in critical care, anesthesiology, and emergency medicine. Infusion of IV fluids at the right temperature partly influences clinical outcomes of critically ill patients. Nowadays, intravenous fluid temperature is poorly managed, as no suitable device is routinely available. Infrared (IR) thermometers have been recently developed for industrial, personal, or medical purposes. The aim of this study was to evaluate the accuracy of an IR thermometer in measuring temperature of warmed and cooled infusion fluids in fluid bags. This study compared temperatures simultaneously recorded by an infrared thermometer and a temperature sensor. Temperatures of warmed (41 degrees C) and cooled (4 degrees C) infusion fluids in fluid bags were recorded by 2 independent operators every minute until IV bags' temperature reached ambient temperature. The relation curve was established with 576 measures. Temperature measures performed with an IR thermometer were perfectly linear and perfectly correlated with the reference method (R(2) = 0.995, P < 10(-5)). Infrared thermometers are efficient to measure IV fluid bag temperature in the range of temperatures used in clinical practice. As these devices are easy to use and inexpensive, they could be largely used in critical care, anesthesiology, or emergency medicine.

Computational fluid mechanics utilizing the variational principle of modeling damping seals

NASA Technical Reports Server (NTRS)

Abernathy, J. M.

1986-01-01

A computational fluid dynamics code for application to traditional incompressible flow problems has been developed. The method is actually a slight compressibility approach which takes advantage of the bulk modulus and finite sound speed of all real fluids. The finite element numerical analog uses a dynamic differencing scheme based, in part, on a variational principle for computational fluid dynamics. The code was developed in order to study the feasibility of damping seals for high speed turbomachinery. Preliminary seal analyses have been performed.

Unravelling the effects of melt depletion and secondary infiltration on mantle Re-Os isotopes beneath the French Massif Central

NASA Astrophysics Data System (ADS)

Harvey, J.; Gannoun, A.; Burton, K. W.; Schiano, P.; Rogers, N. W.; Alard, O.

2010-01-01

Spinel lherzolite xenoliths from Mont Briançon, French Massif Central, retain evidence for multiple episodes of melt depletion and melt/fluid infiltration (metasomatism). Evidence for primary melt depletion is still preserved in the co-variation of bulk-rock major elements (MgO 38.7-46.1 wt.%; CaO 0.9-3.6 wt.%), and many samples yield unradiogenic bulk-rock Os isotope ratios ( 187Os/ 188Os = 0.11541-0.12626). However, many individual xenoliths contain interstitial glasses and melt inclusions that are not in equilibrium with the major primary minerals. Incompatible trace element mass balance calculations demonstrate that metasomatic components comprise a significant proportion of the bulk-rock budget for these elements in some rocks, ranging to as much as 25% of Nd and 40% of Sr Critically, for Re-Os geochronology, melt/fluid infiltration is accompanied by the mobilisation of sulfide. Consequently, bulk-rock isotope measurements, whether using lithophile (e.g. Rb-Sr, Sm-Nd) or siderophile (Re-Os) based isotope systems, may only yield a perturbed and/or homogenised average of these multiple events. Osmium mass balance calculations demonstrate that bulk-rock Os in peridotite is dominated by contributions from two populations of sulfide grain: (i) interstitial, metasomatic sulfide with low [Os] and radiogenic 187Os/ 188Os, and (ii) primary sulfides with high [Os] and unradiogenic 187Os/ 188Os, which have been preserved within host silicate grains and shielded from interaction with transient melts and fluid. The latter can account for >97% of bulk-rock Os and preserve geochronological information of the melt from which they originally precipitated as an immiscible liquid. The Re-depletion model ages of individual primary sulfide grains preserve evidence for melt depletion beneath the Massif Central from at least 1.8 Gyr ago despite the more recent metasomatic event(s).

Anatomy of a deep sub-surface ridge flank aquifer: The "Red Brick" Horizon in ODP Hole 1256D

NASA Astrophysics Data System (ADS)

Teagle, D. A.; Smith-Duque, C. E.; Harris, M.; Rutter, J.; Coggon, R. M.; Tominaga, M.; Alt, J.; Murphy, B.; Banerjee, N.

2012-12-01

Long-lived conductive heat flow deficits, near isothermal basement temperatures, and sedimentary pore water profiles from mid-ocean ridge flanks provide compelling arguments for the substantial lateral movement of seawater-derived fluids within the upper oceanic crust. However, there are few descriptions of zones within the oceanic basement for which there is strong evidence for sustained low temperature hydrothermal fluid flow and alteration. This paper describes a distinctive horizon of intense low temperature alteration encountered in ODP Hole 1256D. Hole 1256D, located on 15 million-year-old East Pacific Rise crust formed at a superfast spreading rate (>200 mm/yr) provides a reference section for fast spreading ocean crust and is the only well to sample a complete section of lavas, sheeted dikes, and into the upper most gabbros. The volcanic sequences at Hole 1256D are >800 m thick. The Red Brick horizon occurs at ~400 m sub-basement (msb) in massive and sheet flows that overly a ~30 m-thick zone of massive flows. These flows probably crystallized at the base of the ridge axial slope within a few 1000 meters of the ridge axis (Tominaga and Umino, 2010). The Red Brick horizon comprises a 50 cm-thick zone of massive, sparsely olivine-phyric microcrystalline basalt that is very strongly (80 to 90%) hydrothermally altered. Olivine, clinopyroxene, and plagioclase are replaced by beidellite, celadonite, K feldspar and iron oxyhydroxide, imparting blue-green and brick red colors to the rock. These secondary minerals plus quartz and carbonate also fill vugs and pore space. Compared to surrounding basalts that exhibit only background levels of low temperature alteration, the rocks of the Red Brick zone are strongly oxidized (Fe3+/FeTot >0.7), hydrated (>4 wt.%), and have highly elevated concentrations of alkali metals (K, Rb, Cs) and Mg. There are strong reductions in Si, Ca, Mn, Zn and Cu. Bulk rock oxygen isotope (δ18O ~8.5 to 9 per mil) indicate hydrothermal alteration at about 70 °C for a seawater-like fluid. 87Sr/86Sr is significantly elevated (0.7033 to 0.7045) compared to primary igneous values but still rock-dominated. The near complete mineral recrystallization should mean that Sr isotope ratios record the signature of the parent hydrothermal fluid. Intriguingly this range is much less radiogenic than our estimate for Site 1256 paleo-black smoker fluids (0.7051 to 0.7053) indicating that the altering fluids are not seawater-diluted black smoker fluids. The core pieces of the Red Brick zone can be confidently identified in the wireline geophysical measurements by integrating formation micro-scanner and gamma ray logs. The occurrence of intense alteration at the Red Brick horizon appears to result from the occurrence of an impermeable unit of massive basalt with few fractures directly below, that may have acted as a long term channel for the lateral flow of ridge flank hydrothermal fluids.

7 CFR 1032.30 - Reports of receipts and utilization.

Code of Federal Regulations, 2013 CFR

2013-01-01

... the following information: (1) Product pounds, pounds of butterfat, pounds of protein, pounds of solids-not-fat other than protein (other solids), and the value of the somatic cell adjustment pursuant... of fluid milk products and bulk fluid cream products; (3) The utilization or disposition of all milk...

7 CFR 1033.30 - Reports of receipts and utilization.

Code of Federal Regulations, 2014 CFR

2014-01-01

... the following information: (1) Product pounds, pounds of butterfat, pounds of protein, pounds of solids-not-fat other than protein (other solids), and the value of the somatic cell adjustment pursuant... of fluid milk products and bulk fluid cream products; (3) The utilization or disposition of all milk...

7 CFR 1032.30 - Reports of receipts and utilization.

Code of Federal Regulations, 2011 CFR

2011-01-01

... the following information: (1) Product pounds, pounds of butterfat, pounds of protein, pounds of solids-not-fat other than protein (other solids), and the value of the somatic cell adjustment pursuant... of fluid milk products and bulk fluid cream products; (3) The utilization or disposition of all milk...

7 CFR 1033.30 - Reports of receipts and utilization.

Code of Federal Regulations, 2012 CFR

2012-01-01

... the following information: (1) Product pounds, pounds of butterfat, pounds of protein, pounds of solids-not-fat other than protein (other solids), and the value of the somatic cell adjustment pursuant... of fluid milk products and bulk fluid cream products; (3) The utilization or disposition of all milk...

7 CFR 1032.30 - Reports of receipts and utilization.

Code of Federal Regulations, 2014 CFR

2014-01-01

... the following information: (1) Product pounds, pounds of butterfat, pounds of protein, pounds of solids-not-fat other than protein (other solids), and the value of the somatic cell adjustment pursuant... of fluid milk products and bulk fluid cream products; (3) The utilization or disposition of all milk...

7 CFR 1033.30 - Reports of receipts and utilization.

Code of Federal Regulations, 2010 CFR

2010-01-01

... the following information: (1) Product pounds, pounds of butterfat, pounds of protein, pounds of solids-not-fat other than protein (other solids), and the value of the somatic cell adjustment pursuant... of fluid milk products and bulk fluid cream products; (3) The utilization or disposition of all milk...

7 CFR 1126.30 - Reports of receipts and utilization.

Code of Federal Regulations, 2010 CFR

2010-01-01

... pool plant operator shall report for each of its operations the following information: (1) Product pounds, pounds of butterfat, pounds of protein, pounds of nonfat solids other than protein (other solids...) Inventories at the beginning and end of the month of fluid milk products and bulk fluid cream products; (3...

7 CFR 1032.30 - Reports of receipts and utilization.

Code of Federal Regulations, 2012 CFR

2012-01-01

... the following information: (1) Product pounds, pounds of butterfat, pounds of protein, pounds of solids-not-fat other than protein (other solids), and the value of the somatic cell adjustment pursuant... of fluid milk products and bulk fluid cream products; (3) The utilization or disposition of all milk...

7 CFR 1126.30 - Reports of receipts and utilization.

Code of Federal Regulations, 2011 CFR

2011-01-01

... pool plant operator shall report for each of its operations the following information: (1) Product pounds, pounds of butterfat, pounds of protein, pounds of nonfat solids other than protein (other solids...) Inventories at the beginning and end of the month of fluid milk products and bulk fluid cream products; (3...

7 CFR 1124.30 - Reports of receipts and utilization.

Code of Federal Regulations, 2011 CFR

2011-01-01

... the following information: (1) Product pounds, pounds of butterfat, pounds of protein, and pounds of solids-not-fat other than protein (other solids) contained in or represented by: (i) Receipts of producer... and end of the month of fluid milk products and bulk fluid cream products; (3) The utilization or...

7 CFR 1126.30 - Reports of receipts and utilization.

Code of Federal Regulations, 2013 CFR

2013-01-01

... pool plant operator shall report for each of its operations the following information: (1) Product pounds, pounds of butterfat, pounds of protein, pounds of nonfat solids other than protein (other solids...) Inventories at the beginning and end of the month of fluid milk products and bulk fluid cream products; (3...

7 CFR 1124.30 - Reports of receipts and utilization.

Code of Federal Regulations, 2013 CFR

2013-01-01

... the following information: (1) Product pounds, pounds of butterfat, pounds of protein, and pounds of solids-not-fat other than protein (other solids) contained in or represented by: (i) Receipts of producer... and end of the month of fluid milk products and bulk fluid cream products; (3) The utilization or...

7 CFR 1124.30 - Reports of receipts and utilization.

Code of Federal Regulations, 2010 CFR

2010-01-01

... the following information: (1) Product pounds, pounds of butterfat, pounds of protein, and pounds of solids-not-fat other than protein (other solids) contained in or represented by: (i) Receipts of producer... and end of the month of fluid milk products and bulk fluid cream products; (3) The utilization or...

7 CFR 1126.30 - Reports of receipts and utilization.

Code of Federal Regulations, 2012 CFR

2012-01-01

... pool plant operator shall report for each of its operations the following information: (1) Product pounds, pounds of butterfat, pounds of protein, pounds of nonfat solids other than protein (other solids...) Inventories at the beginning and end of the month of fluid milk products and bulk fluid cream products; (3...

7 CFR 1032.30 - Reports of receipts and utilization.

Code of Federal Regulations, 2010 CFR

2010-01-01

... the following information: (1) Product pounds, pounds of butterfat, pounds of protein, pounds of solids-not-fat other than protein (other solids), and the value of the somatic cell adjustment pursuant... of fluid milk products and bulk fluid cream products; (3) The utilization or disposition of all milk...

7 CFR 1126.30 - Reports of receipts and utilization.

Code of Federal Regulations, 2014 CFR

2014-01-01

... pool plant operator shall report for each of its operations the following information: (1) Product pounds, pounds of butterfat, pounds of protein, pounds of nonfat solids other than protein (other solids...) Inventories at the beginning and end of the month of fluid milk products and bulk fluid cream products; (3...

7 CFR 1033.30 - Reports of receipts and utilization.

Code of Federal Regulations, 2013 CFR

2013-01-01

... the following information: (1) Product pounds, pounds of butterfat, pounds of protein, pounds of solids-not-fat other than protein (other solids), and the value of the somatic cell adjustment pursuant... of fluid milk products and bulk fluid cream products; (3) The utilization or disposition of all milk...

7 CFR 1033.30 - Reports of receipts and utilization.

Code of Federal Regulations, 2011 CFR

2011-01-01

... the following information: (1) Product pounds, pounds of butterfat, pounds of protein, pounds of solids-not-fat other than protein (other solids), and the value of the somatic cell adjustment pursuant... of fluid milk products and bulk fluid cream products; (3) The utilization or disposition of all milk...

7 CFR 1124.30 - Reports of receipts and utilization.

Code of Federal Regulations, 2012 CFR

2012-01-01

... the following information: (1) Product pounds, pounds of butterfat, pounds of protein, and pounds of solids-not-fat other than protein (other solids) contained in or represented by: (i) Receipts of producer... and end of the month of fluid milk products and bulk fluid cream products; (3) The utilization or...

7 CFR 1124.30 - Reports of receipts and utilization.

Code of Federal Regulations, 2014 CFR

2014-01-01

... the following information: (1) Product pounds, pounds of butterfat, pounds of protein, and pounds of solids-not-fat other than protein (other solids) contained in or represented by: (i) Receipts of producer... and end of the month of fluid milk products and bulk fluid cream products; (3) The utilization or...

Probing Chemical Properties of Interstitial Micro-fluids in Ice

NASA Astrophysics Data System (ADS)

Cheng, J.; Colussi, A. J.; Hoffmann, M. R.

2007-12-01

Liquid is present as microscopic channels in polycrystalline ice at sub-freezing and even sub-eutectic temperatures. Not only do chemicals tend to concentrate substantially in this microscopic liquid phase, but local physicochemical properties may also differ widely from the bulk counterparts, therefore critically affecting the thermodynamics and kinetics of chemical processes occurring in frozen media such as snow, frost, and frost- flowers. This phenomenon has important implications in atmospheric chemistry such as affecting the composition of the atmospheric boundary layer in snow-covered regions. A method using con-focal laser scanning microscope equipped with a cryostat has been developed to measure physicochemical properties of the microscopic liquid phase in ice that are not readily extrapolated from the bulk data. The experimental setup allows for monitoring the freezing process of an aqueous solution with a sub- second time resolution and a submicron 3D spatial resolution. The physicochemical properties (e.g. viscosity, polarity, and acidity) can, in theory, be deduced from features of the fluorescence spectra of particular fluorescent indicators. For example, the acidity change during the freezing and melting process of electrolyte solutions has been monitored in real time by a pH-dependent dual emission fluorescent probe C-SNARF-1. The effects of temperature, freezing rate, and added electrolytes such as ammonium sulfate, sodium chloride and zwitterions are also examined. The findings complement the theory and previous experimental evidence of freezing hydrolysis.

PREFACE: Ionic fluids Ionic fluids

NASA Astrophysics Data System (ADS)

Levin, Yan; Kornyshev, Alexei; Barbosa, Marcia C.

2009-10-01

In spite of its apparent simplicity Coulomb law, when applied to many body systems, leads to an amazingly rich mathematical structure. The simple idea that two similarly charged objects always repel, is not necessarily true in a colloidal suspension or a dusty plasma. Neither can one simply predict the direction of the electrophoretic motion of a polyion from only knowing its chemical charge. Strong Coulomb correlations in ionic fluids result in instabilities very similar to the gas--liquid phase separation observed in atomic fluids. It is fair to say that bulk behavior of simple aqueous monovalent electrolytes is now very well understood. Unfortunately this is not the case for multivalent electrolytes or molten salts. In these systems cation-anion association leads to strong non-linear effects which manifest themselves in formations of tightly bound ionic clusters. In spite of the tremendous effort invested over the years, our understanding of these systems remains qualitative. In this special issue we have collected articles from some of the biggest experts working on ionic fluids. The papers are both experimental and theoretical. They range from simple electrolytes in the bulk and near interfaces, to polyelectrolytes, colloids, and molten salts. The special issue, covers a wide spectrum of the ongoing research on ionic fluids. All readers should find something of interest here.

Abnormal temperature dependence of conductance of single Cd-doped ZnO nanowires

NASA Astrophysics Data System (ADS)

Li, Q. H.; Wan, Q.; Wang, Y. G.; Wang, T. H.

2005-06-01

Positive temperature coefficient of resistance is observed on single Cd-doped ZnO nanowires. The current along the nanowire increases linearly with the bias and saturates at large biases. The conductance is greatly enhanced either by ultraviolet illumination or infrared illumination. However, the conductance decreases with increasing temperature, in contrast to the reported temperature behavior either for ZnO nanostructures or for CdO nanoneedles. The increase of the conductance under illumination is related to surface effect and the decrease with increasing temperature to bulk effect. These results show that Cd doping does not change surface effect but affects bulk effect. Such a bulk effect could be used to realize on-chip temperature-independent varistors.

Temperature and volumetric water content petrophysical relationships in municipal solid waste for the interpretation of bulk electrical resistivity data

NASA Astrophysics Data System (ADS)

Pilawski, Tamara; Dumont, Gaël; Nguyen, Frédéric

2015-04-01

Landfills pose major environmental issues including long-term methane emissions, and local pollution of soil and aquifers but can also be seen as potential energy resources and mining opportunities. Water content in landfills determine whether solid fractions can be separated and recycled, and controls the existence and efficiency of natural or enhanced biodegradation. Geophysical techniques, such as electrical and electromagnetic methods have proven successful in the detection and qualitative investigation of sanitary landfills. However, their interpretation in terms of quantitative water content estimates makes it more challenging due to the influence of parameters such as temperature, compaction, waste composition or pore fluid. To improve the confidence given to bulk electrical resistivity data and to their interpretation, we established temperature and volumetric water content petrophysical relationships that we tested on field and laboratory electrical resistivity measurements. We carried out two laboratory experiments on leachates and waste samples from a landfill located in Mont-Saint-Guibert, Belgium. We determined a first relationship between temperature and electrical resistivity with pure and diluted leachates by progressively increasing the temperature from 5°C to 65°C, and then cooling down to 5°C. The second relationship was obtained by measuring electrical resistivity on waste samples of different volumetric water contents. First, we used the correlations obtained from the experiments to compare electrical resistivity measurements performed in a landfill borehole and on reworked waste samples excavated at different depths. Electrical resistivities were measured every 20cm with an electromagnetic logging device (EM39) while a temperature profile was acquired with optic fibres. Waste samples were excavated every 2m in the same borehole. We filled experimental columns with these samples and measured electrical resistivities at laboratory temperature. We made corrections according to the temperature profile and to volumetric water contents obtained previously on undisturbed samples. Corrected values tended to be superimposed on those obtained in the field. Then, we calculated the water content of the different reworked waste samples using the correlation between volumetric water content correlation and electrical resistivity and we compared this value to the one measured at the laboratory. Both values were correlated satisfactorily. In conclusion, we show that bulk electrical resistivity measurements are very promising to quantify water content in landfills if temperature can be estimated independently. In future applications, electrical resistivity tomography coupled with distributed temperature sensing could give important estimates of water content of the waste and thus helping in dealing with problematics such as boosting biodegradation and stabilization of the waste, reducing risks of soil and aquifers pollution, landfill mining, and controlled production of methane.

Phase relations among K-feldspar, muscovite and H2O at 1.0 GPa and 800°C: Implications for metasediment dissolution and melting at high pressures and temperatures

NASA Astrophysics Data System (ADS)

Fineman, D.; Manning, C. E.

2016-12-01

Melting and solubility of K-feldspar (ksp) and muscovite (mus) were investigated in the system KSi3O6.5 -Al2O3 - H2O at 1.0 GPa and 800 °C with rapid-quench piston-cylinder techniques. Equilibrium assemblages of ksp, mus, silicate liquid (L) and aqueous fluid (V) were deduced from optical and scanning electron microscopy. Quenched silicate liquids and aqueous fluids were distinguished using the methodology of Burnham and Jahns (1962, Am J Sci, 260, 721) and Makhluf et al. (2016, CMP, in press). Experiments on a range of bulk compositions constrain the locations of the V, ksp+V, ms+V, and ksp+L+V fields. This allowed geometrical constraints to be placed on additional phase boundaries in the ternary system. The results show that ksp dissolves incongruently in H2O, with residual liquid or ms depending on the fluid-rock ratio. In contrast, ms dissolves congruently in H2O and KSi3O6.5 -H2O solutions with up to 25 wt% KSi3O6.5. Results indicate that stable hydrous liquid at these conditions has an Al content intermediate between ksp and ms. There is no stable liquid along the ksp-H2O join, consistent with results of Goldsmith and Peterson (1990, Am Min, 75, 1362). All data are consistent with the stability of a supercritical fluid on the KAlSi3O8 -H2O join, with 5-10 wt% dissolved Al2O3. Compositional constraints imply that the liquid phase contains 25 wt% H2O and coexists with a V phase containing 25 wt% dissolved solutes. This in turn implies critical mixing of the fluid phases at higher temperature, which is similar to the systems NaAlSi3O8-H2O and simple granite-H2O. Our results help constrain the conditions of production of supercritical granitic-H2O fluids systems in deep crustal and subduction zone settings.

Tank Pressure Control Experiment: Thermal Phenomena in Microgravity. Video 3 of 4

NASA Technical Reports Server (NTRS)

1996-01-01

The report presents the results of the flight experiment Tank Pressure Control Experiment/Thermal Phenomena (TPCE/TP) performed in the microgravity environment of the space shuttle. TPCE/TP, flown on the Space Transportation System STS-52, was a second flight of the Tank Pressure Control Experiment (TPCE). The experiment used Freon 113 at near saturation conditions. The test tank was filled with liquid to about 83 percent by volume. The experiment consisted of 21 tests. Each test generally started with a heating phase to increase the tank pressure and to develop temperature stratification in the fluid, followed by a fluid mixing phase for the tank pressure reduction and fluid temperature equilibration. The heating phase provided pool boiling data from large (relative to bubble sizes) heating surfaces (0.1046 m by 0.0742 m) at low heat fluxes (0.23 to 1.16 kW/m(exp 2)). The system pressure and the bulk liquid subcooling varied from 39 to 78 kPa and 1 to 3 deg C, respectively. The boiling process during the entire heating period, as well a jet-induced mixing process for the first 2 min. of the mixing period, was also recorded on video. Analyses of data from the two flight experiments (TPCE and TPCE/TP) and their comparison with the results obtained in drop tower experiments suggest that as Bond number approaches zero the flow pattern produced by an axial jet and the mixing time can be predicted by the Weber number. This is video 3 of 4.

Tank Pressure Control Experiment: Thermal Phenomena in Microgravity. Video 4 of 4

NASA Technical Reports Server (NTRS)

1996-01-01

The report presents the results of the flight experiment Tank Pressure Control Experiment/Thermal Phenomena (TPCE/TP) performed in the microgravity environment of the space shuttle. TPCE/TP, flown on the Space Transportation System STS-52, was a second flight of the Tank Pressure Control Experiment (TPCE). The experiment used Freon 113 at near saturation conditions. The test tank was filled with liquid to about 83 percent by volume. The experiment consisted of 21 tests. Each test generally started with a heating phase to increase the tank pressure and to develop temperature stratification in the fluid, followed by a fluid mixing phase for the tank pressure reduction and fluid temperature equilibration. The heating phase provided pool boiling data from large (relative to bubble sizes) heating surfaces (0.1046 m by 0.0742 m) at low heat fluxes (0.23 to 1.16 kW/m(exp 2)). The system pressure and the bulk liquid subcooling varied from 39 to 78 kPa and 1 to 3 deg C, respectively. The boiling process during the entire heating period, as well a jet-induced mixing process for the first 2 min. of the mixing period, was also recorded on video. Analyses of data from the two flight experiments (TPCE and TPCE/TP) and their comparison with the results obtained in drop tower experiments suggest that as Bond number approaches zero the flow pattern produced by an axial jet and the mixing time can be predicted by the Weber number. This is video 4 of 4.

Tank Pressure Control Experiment: Thermal Phenomena in Microgravity. Video 1 of 4

NASA Technical Reports Server (NTRS)

1996-01-01

The report presents the results of the flight experiment Tank Pressure Control Experiment/Thermal Phenomena (TPCE/TP) performed in the microgravity environment of the space shuttle. TPCE/TP, flown on the Space Transportation System STS-52, was a second flight of the Tank Pressure Control Experiment (TPCE). The experiment used Freon 113 at near saturation conditions. The test tank was filled with liquid to about 83 percent by volume. The experiment consisted of 21 tests. Each test generally started with a heating phase to increase the tank pressure and to develop temperature stratification in the fluid, followed by a fluid mixing phase for the tank pressure reduction and fluid temperature equilibration. The heating phase provided pool boiling data from large (relative to bubble sizes) heating surfaces (0.1046 m by 0.0742 m) at low heat fluxes (0.23 to 1.16 kW/m(exp 2)). The system pressure and the bulk liquid subcooling varied from 39 to 78 kPa and 1 to 3 deg C, respectively. The boiling process during the entire heating period, as well a jet-induced mixing process for the first 2 min. of the mixing period, was also recorded on video. Analyses of data from the two flight experiments (TPCE and TPCE/TP) and their comparison with the results obtained in drop tower experiments suggest that as Bond number approaches zero the flow pattern produced by an axial jet and the mixing time can be predicted by the Weber number. This is video 1 of 4.

Tank Pressure Control Experiment: Thermal Phenomena in Microgravity. Video 2 of 4

NASA Technical Reports Server (NTRS)

1996-01-01

The report presents the results of the flight experiment Tank Pressure Control Experiment/Thermal Phenomena (TPCE/TP) performed in the microgravity environment of the space shuttle. TPCE/TP, flown on the Space Transportation System STS-52, was a second flight of the Tank Pressure Control Experiment (TPCE). The experiment used Freon 113 at near saturation conditions. The test tank was filled with liquid to about 83 percent by volume. The experiment consisted of 21 tests. Each test generally started with a heating phase to increase the tank pressure and to develop temperature stratification in the fluid, followed by a fluid mixing phase for the tank pressure reduction and fluid temperature equilibration. The heating phase provided pool boiling data from large (relative to bubble sizes) heating surfaces (0.1046 m by 0.0742 m) at low heat fluxes (0.23 to 1.16 kW/m(exp 2)). The system pressure and the bulk liquid subcooling varied from 39 to 78 kPa and 1 to 3 deg C, respectively. The boiling process during the entire heating period, as well a jet-induced mixing process for the first 2 min. of the mixing period, was also recorded on video. Analyses of data from the two flight experiments (TPCE and TPCE/TP) and their comparison with the results obtained in drop tower experiments suggest that as Bond number approaches zero the flow pattern produced by an axial jet and the mixing time can be predicted by the Weber number. This is video 2 of 4.

Hydrous orthopyroxene-rich pyroxenite source of the Xinkailing high magnesium andesites, Western Liaoning: Implications for the subduction-modified lithospheric mantle and the destruction mechanism of the North China Craton

NASA Astrophysics Data System (ADS)

Hong, Lu-Bing; Zhang, Yin-Hui; Xu, Yi-Gang; Ren, Zhong-Yuan; Yan, Wen; Ma, Qiang; Ma, Liang; Xie, Wei

2017-06-01

Metasomatism of the lithospheric mantle by subduction-related fluids/melts is recorded in the Early Cretaceous Xinkailing high magnesium andesites (HMAs) from Western Liaoning. Olivine-hosted melt inclusions within the Xinkailing HMAs are alkaline and record a much lower SiO2 content and higher Al2O3 and CaO contents than the sub-alkaline bulk rock compositions. These observed compositional differences between bulk rocks and melt inclusions suggest that a crustally derived, high-SiO2 melt was incorporated in the Xinkailing HMAs within the pre-eruptive magma chamber. The process of this incorporation accounts for the compositional differences between upper (HMAs) and lower (high magnesium basalts) successions of the Yixian Formation. Olivine phenocrysts also record unusually high Ni and Ni/MgO contents with high Fo values. Based on the fact that bulk rocks record low Ni contents, whereas olivine crystals record a steep correlation between Fo and Ni and low CaO and CaO/FeO contents, in addition to the likely considerable depression of the olivine liquidus temperature, we argue that a hydrous (2-6% H2O) orthopyroxene-rich pyroxenite source was formed by the reaction between subducted slab-released SiO2-rich fluids and overlying mantle peridotite. We further propose that during a series of Phanerozoic successive subduction events around the Eastern NCC, a significant amount of water may have been transported to the lithospheric mantle, thus lowering its viscosity and ultimately destabilizing the cratonic lithosphere. Hydrous experiments data (circles filled by yellow color) used to parameterize the equation after screened several data significantly deviates from the line (circles without color). Data source: Gaetani and Grove (1998); Almeev et al. (2007); Médard and Grove (2008); Tenner et al. (2009); Mitchell and Grove (2015).

Unipolar memristive Switching in Bulk Negative Temperature Coefficient Thermosensitive Ceramics

PubMed Central

Wu, Hongya; Cai, Kunpeng; Zhou, Ji; Li, Bo; Li, Longtu

2013-01-01

A memristive phenomenon was observed in macroscopic bulk negative temperature coefficient nickel monoxide (NiO) ceramic material. Current-voltage characteristics of memristors, pinched hysteretic loops were systematically observed in the Ag/NiO/Ag cell. A thermistor-based model for materials with negative temperature coefficient was proposed to explain the mechanism of the experimental phenomena. Most importantly, the results demonstrate the potential for a realization of memristive systems based on macroscopic bulk materials. PMID:24255717

Low-resistivity bulk silicon prepared by hot-pressing boron- and phosphorus-hyperdoped silicon nanocrystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luan, Qingbin; Ni, Zhenyi; Zhu, Tiejun

2014-12-15

Technologically important low-resistivity bulk Si has been usually produced by the traditional Czochralski growth method. We now explore a novel method to obtain low-resistivity bulk Si by hot-pressing B- and P-hyperdoped Si nanocrystals (NCs). In this work bulk Si with the resistivity as low as ∼ 0.8 (40) mΩ•cm has been produced by hot pressing P (B)-hyperdoped Si NCs. The dopant type is found to make a difference for the sintering of Si NCs during the hot pressing. Bulk Si hot-pressed from P-hyperdoped Si NCs is more compact than that hot-pressed from B-hyperdoped Si NCs when the hot-pressing temperature ismore » the same. This leads to the fact that P is more effectively activated to produce free carriers than B in the hot-pressed bulk Si. Compared with the dopant concentration, the hot-pressing temperature more significantly affects the structural and electrical properties of hot-pressed bulk Si. With the increase of the hot-pressing temperature the density of hot-pressed bulk Si increases. The highest carrier concentration (lowest resistivity) of bulk Si hot-pressed from B- or P-hyperdoped Si NCs is obtained at the highest hot-pressing temperature of 1050 °C. The mobility of carriers in the hot-pressed bulk Si is low (≤  ∼ 30 cm{sup -2}V{sup -1}s{sup -1}) mainly due to the scattering of carriers induced by structural defects such as pores.« less

A Two-Dimensional Liquid Structure Explains the Elevated Melting Temperatures of Gallium Nanoclusters.

PubMed

Steenbergen, Krista G; Gaston, Nicola

2016-01-13

Melting in finite-sized materials differs in two ways from the solid-liquid phase transition in bulk systems. First, there is an inherent scaling of the melting temperature below that of the bulk, known as melting point depression. Second, at small sizes changes in melting temperature become nonmonotonic and show a size-dependence that is sensitive to the structure of the particle. Melting temperatures that exceed those of the bulk material have been shown to occur for a very limited range of nanoclusters, including gallium, but have still never been ascribed a convincing physical explanation. Here, we analyze the structure of the liquid phase in gallium clusters based on molecular dynamics simulations that reproduce the greater-than-bulk melting behavior observed in experiments. We observe persistent nonspherical shape distortion indicating a stabilization of the surface, which invalidates the paradigm of melting point depression. This shape distortion suggests that the surface acts as a constraint on the liquid state that lowers its entropy relative to that of the bulk liquid and thus raises the melting temperature.

Initial fuel temperature effects on burning rate of pool fire.

PubMed

Chen, Bing; Lu, Shou-Xiang; Li, Chang-Hai; Kang, Quan-Sheng; Lecoustre, Vivien

2011-04-15

The influence of the initial fuel temperature on the burning behavior of n-heptane pool fire was experimentally studied at the State Key Laboratory of Fire Science (SKLFS) large test hall. Circular pool fires with diameters of 100mm, 141 mm, and 200 mm were considered with initial fuel temperatures ranging from 290 K to 363 K. Burning rate and temperature distributions in fuel and vessel wall were recorded during the combustion. The burning rate exhibited five typical stages: initial development, steady burning, transition, bulk boiling burning, and decay. The burning rate during the steady burning stage was observed to be relatively independent of the initial fuel temperature. In contrast, the burning rate of the bulk boiling burning stage increases with increased initial fuel temperature. It was also observed that increased initial fuel temperature decreases the duration of steady burning stage. When the initial temperature approaches the boiling point, the steady burning stage nearly disappears and the burning rate moves directly from the initial development stage to the transition stage. The fuel surface temperature increases to its boiling point at the steady burning stage, shortly after ignition, and the bulk liquid reaches boiling temperature at the bulk boiling burning stage. No distinguished cold zone is formed in the fuel bed. However, boiling zone is observed and the thickness increases to its maximum value when the bulk boiling phenomena occurs. Copyright © 2011 Elsevier B.V. All rights reserved.

Effect of sintering temperatures on the in vitro bioactivity, molecular structure and mechanical properties of titanium/carbonated hydroxyapatite nanobiocomposites

NASA Astrophysics Data System (ADS)

Youness, Rasha A.; Taha, Mohammed A.; Ibrahim, Medhat A.

2017-12-01

Titanium-containing carbonated hydroxyapatite (Ti-CHA) nanocomposite powders, with different CHA contents, have been prepared using high-energy ball milling method. The effect of sintering temperatures, 900, 1100 and 1300 °C on molecular structure and microstructure of these samples were examined by XRD; Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM), respectively. Furthermore, their mechanical properties including hardness, longitudinal modulus, Young's modulus, shear modulus, bulk modulus and Poisson's ratio were measured by ultrasonic non-destructive technique. Moreover, bioactivity of sintered samples at different firing temperatures was assessed by immersing them in simulated body fluid at 37 ± 0.5 °C for 7 days and then, analyzed by FTIR spectroscopy. The results pointed out that increasing sintering temperature up to 1100 °C caused significant increases in densities and mechanical properties of these nanocomposite samples. However, further increase of firing temperature to 1300 °C was responsible for complete CHA decomposition and the resultant α-tricalcium (α-TCP) phase greatly affected these properties. On the contrary, better bioactivity was observed for sintered samples at 900 °C only. However, increase of sintering temperature of these samples up to 1300 °C led to severe decrease in their bioactivity due to the formation of highly soluble α-TCP phase.

Unraveling multiple phases of sulfur cycling during the alteration of ancient ultramafic oceanic lithosphere

NASA Astrophysics Data System (ADS)

Schwarzenbach, Esther M.; Gill, Benjamin C.; Johnston, David T.

2018-02-01

Ultramafic-hosted hydrothermal systems - characterized by ongoing serpentinization reactions - exert an important influence on the global sulfur cycle. Extensive water-rock interaction causes elemental exchange between seawater and the oceanic lithosphere, effectively removing sulfate from seawater through both abiogenic and biogenic processes. Here, we use bulk rock multiple sulfur isotope signatures (32S, 33S, 34S) and in situ sulfide analyses together with petrographic observations to track the sulfur cycling processes and the hydrothermal evolution of ancient peridotite-hosted hydrothermal systems. We investigate serpentinized peridotites from the Northern Apennine ophiolite in Italy and the Santa Elena ophiolite in Costa Rica and compare those with the Iberian Margin (Ocean Drilling Program (ODP) Leg 149 and 173) and the 15°20‧N Fracture Zone along the Mid-Atlantic Ridge (ODP Leg 209). In situ measurements of sulfides in the Northern Apennine serpentinites preserve a large range in δ34Ssulfide of -33.8 to +13.3‰ with significant heterogeneities within single sulfide grains and depending on mineralogy. Detailed mineralogical investigation and comparison with bulk rock Δ33Ssulfide and in situ δ34Ssulfide data implies a thermal evolution of the system from high temperatures (∼350 °C) that allowed thermochemical sulfate reduction and input of hydrothermal sulfide to lower temperatures (<120 °C) that permitted microbial activity. The change in temperature regime is locally preserved in individual samples and correlates with the progressive uplift and exposure of mantle rock associated with detachment faulting along a mid-ocean ridge spreading center. The Santa Elena peridotites preserve distinct signatures for fluid circulation at high temperatures with both closed system thermochemical sulfate reduction and input of mafic-derived sulfur. In addition, the peridotites provide strong evidence that low Ca2+ concentrations in peridotite-hosted systems can limit sulfate removal during anhydrite precipitation at temperatures above 150 °C. This may play a central role for the availability of sulfate to microbial communities within these systems. Overall, the combined application of in situ and bulk rock multiple sulfur isotope measurements with petrographic observations allows us to resolve the different episodes of sulfur cycling during alteration of the oceanic lithosphere and the temporal changes between abiogenic and biogenic processes that control the sulfur cycling in these systems.

[Effect of sludge bulking on membrane fouling of MBR under low temperature].

PubMed

Ren, Nan-qi; Liu, Jiao; Wang, Xiu-heng

2009-01-01

The performance and membrane fouling of submerged membrane bioreactor were studied in the case of active sludge bulking under low temperature. The factors contributing to membrane fouling were discussed from the microorganism aspect. The results showed that COD removal efficiencies of supernatant and permeate were 85% and 92% respectively and filamentous sludge bulking had little impact on them. The sludge settleability became bad and the filament index (FI) increased from 2 to 5 during the formation of filamentous sludge bulking under low temperature. The filamentous bacteria extending from the sludge flocs formed net structure. Membrane fouling changed with time in linear under low temperature and the operation period of MBR was 15 d. However, membrane fouling was more serious in the condition of filamentous sludge bulking at low temperature, shortening the operation period of MBR to 7 d. The extracellular polymeric substances (EPS) content of bulking sludge was three times as that of normal sludge and the relative hydrophobicity (RH) of sludge flocs was decreased as FI increased. The increase of EPS and RH may cause more materials to deposit on the membrane surface, thus the membrane fouling rate improved and the operation period of MBR became short. Further analysis indicated that the mixed liquid viscosity, Zeta potential and sludge floc structure were all important factors of membrane fouling.

Dynamical studies of confined fluids and polymers

NASA Astrophysics Data System (ADS)

Grabowski, Christopher A.

Soft matter, a class of materials including polymers, colloids, and surfactant molecules, are ubiquitous in our everyday lives. Plastics, soaps, foods and living organisms are mostly comprised of soft materials. Research conducted to understand soft matter behavior at the molecular level is essential to create new materials with unique properties. Self-healing plastics, targeted drug delivery, and nanowire assemblies have all been further advanced by soft matter research. The author of this dissertation investigates fundamental soft matter systems, including polymer solutions and melts, colloid dispersions in polymer melts, and interfacial fluids. The dynamics of polymers and confined fluids were studied using the single-molecule sensitive technique of fluorescence correlation spectroscopy (FCS). Here, fluorescent dyes are attached to polymer coils or by introducing free dyes directly into the solution/film. Complementary experiments were also performed, utilizing atomic force microscopy (AFM) and ellipsometry. FCS and AFM experiments demonstrated the significant difference in properties of thin fluid films of the nearly spherical, nonpolar molecule TEHOS (tetrakis(2-ethylhexoxy)silane) when compared to its bulk counterpart. AFM experiments confirmed TEHOS orders in layers near a solid substrate. FCS experiments show that free dyes introduced in these thin films do not have a single diffusion coefficient, indicating that these films have heterogeneity at the molecular level. FCS experiments have been applied to study the diffusion of gold colloids. The diffusion of gold colloids in polymer melts was found to dramatically depart from the Stokes-Einstein prediction when colloid size was smaller than the surrounding polymer mesh size. This effect is explained by noting the viscosity experienced by the colloid is not equivalent to the overall bulk viscosity of the polymer melt. The conformational change of polymers immersed in a binary solvent was measured via FCS. This experiment was conducted to test a theory proposed by Brochard and de Gennes, who postulated a polymer chain undergoes a collapse and a dramatic re-swelling as the critical point of the binary mixture is approached. Measuring polymer chain diffusion as a function of temperature, this theory was confirmed. To my knowledge, this was the first experimental evidence of contraction/re-swelling for polymers in critical binary solvents.

Constraints on Fault Permeability from Helium and Heat Flow in the Los Angeles Basin

NASA Astrophysics Data System (ADS)

Garven, G.; Boles, J. R.

2016-12-01

Faults have profound controls on fluid flow in the Earth's crust. Faults affect the diagenesis of sediments, the migration of brines and petroleum, and the dynamics of hydrothermal mineralization. In southern California, the migration of petroleum and noble gases can be used to constrain fault permeability at both the formation and crustal scale. In the Los Angeles Basin, mantle-derived helium is a significant component of casing gas from deep production wells along the Newport-Inglewood Fault zone (NIFZ). Helium isotope ratios are as high as 5.3 Ra, indicating up to 66% mantle contribution along parts of this strike-slip fault zone (Boles et al., 2015). The 3He inversely correlates with CO2, a potential magmatic-derived carrier gas, and the d13C of the CO2 in the 3He rich samples is between 0 and -10 per mil, suggesting a mantle influence. The strong mantle-helium signal along the NIFZ is surprising, considering that the fault is currently in a transpressional state of stress (rather than extensional), has no history of recent magma emplacement, and lacks high geothermal gradients. Structurally it has been modeled as being truncated by a "potentially seismically active" décollement beneath the LA basin. But the geochemical data demonstrate that the NIFZ is a deep-seated fault connected with the mantle. Assuming that the helium migration is linked to the bulk fluid transport in the crust, we have used 1-D reactive mass transport theory to calculate a maximum inter-seismic Darcy flow rate of 2.2 cm yr-1 and intrinsic permeability of 160 microdarcys (1.6 x 10 -16 m2), vertically averaged across the crust. Based on thermal Peclet numbers and numerical models for the basin, we show that fault-focused fluid flow is too slow to elevate heat flow around the NIFZ. Although heat flow data are sparse, there generally doesn't appear to be any clear pattern of anomalous heat flow with the large strike-slip faults of southern California, suggesting that neither bulk fluid flow nor frictional heating alter the conductive temperature regime.

Isotopic studies of authigenic sulfides, silicates and carbonates, and calcite and pyrite veinlets in the Creede Formation, San Juan Mountains, Southwest Colorado

USGS Publications Warehouse

Bethke, Philip M.; Rye, Robert O.; Finkelstein, David B.

2000-01-01

Sulfur isotope analysis of authigenic pyrite in the Creede Formation documents its precipitation by the reaction between iron in the volcaniclastic sediments and H2S formed through bacteriogenic reduction of sulfate added to the lake during and immediately following repeated volcanic eruptions during sedimentation. Pyrite veinlets in the underlying Snowshoe Mountain Tuff were formed by the percolation of H2S-bearing pore waters into fractures in the tuff. Conventional analyses of bulk samples of authigenic pyrite range from -20.4% to 34.5% essentially equivalent to the range of -30% to 40% determined using SHRIMP microprobe techniques. Conventional analyses of bulk samples of pyrite from veinlets in the Snowshow Mountain Tiff range from -3.5% to 17.6% much more limited than the ranges of -23% to 111% and -15.6% to 67.0% determined by SHRIMP and laser ablation microbeam techniques, respectively. The extreme range of δ34S for the veinlets is interpreted to be the result of continued fractionation of the already 34S-depleted pore water. Oxygen isotope analysis of authigenic smectite, kaolinite, and K-feldspar together with fluid-inclusion temperatures and oxygen isotope analysis of calcite coexisting with kaolinite indicate that the smectites formed early during burial diagenesis, in accord with petrographic observations. The 40Ar/39Ar dating of K-feldspar, concorfance of K-feldspar, kaolinite, and calcite δ18O values, and fluid-inclusion temperatures in calcite, indicate that the sediments at core hole CCM-1 were subjected to a hydrothermal event at 17.6 Ma. The minerals formed oxygen-shifted meteoric waters with δ18O values of ~-9% Smecities at CCM-1 at least partially exchanged with these waters. Carbon and oxygen isotope analysis of authigenic calcites in the Creede Formation show that they formed over a wide range of temperatures from fluids having a wide range of isotopic composition, presumably over an extended period time. Some of the cements apparently formed very late from unexchanged meteoric water. Concretions and possibly some cements at CCM-1 appear to have exchanged with the 17.6 Ma oxygen-shifted hydrothermal fluids. Such exchange is consistent with evidence that lacustrine carbonates at CCM-1 exchanged with low 18O waters, whereas those at CCM-2 underwent little, if any, exchange. The δ13C-δ18O values for calcite veinlets in the Creede Formation are similar to those for authegenic calcites. Fluid-inclusion temperatures and δ18O indicate that some were deposited during the 17.6 Ma hydrothermal event and others from unexchanged meteoric water at a later date. The isotope studies confirm that part of the model of Rye et al., proposing that the barites in the southern end of the Creede Mining District were formed by mixing of the Creede hydrotermal system with Lake Creede pore of lake waters. The silicate and carbonate isotope data indicate that the pores of the Creede Formation were occupied by at least three isotopically distinct water since the time of deposition. The original pore fluids were probably shifted to lower δ18O values during burial diagensis as a result of the hydrolysis of the volcanic glass to for smectites and other hydrous silicates. During or prior to a 17.6 Ma hydrothermal event in the vicinity of CCM-1, the Creede Formation was flushed with oxygen-shifted meteoric water, possibly related to the breaching of the east side of the caldera wall sometime between 20 and 22 Ma. Later, the Creede Formation was again flushed, this time with unexchanged meteoric water with δD-δ18O values of present-day waters, possibly during the incision of the Rio Grande drainage during uplifting of the southern Rocky Mountains beginning about 5 Ma.

Experimental investigation on the failure of T-joints at elevated temperature under unaxial loading

NASA Astrophysics Data System (ADS)

Bahri, N. F.; Afendi, M.; Razlan, Z. M.; Nor, A.; Baharuddin, S. A.

2017-09-01

In this study, the mechanical properties and maximum failure load of a bulk and T-joints subjected to tensile loading were investigated experimentally. A bulk and the T-joint specimens were fabricated and tested in order to investigate the effects of temperature conditions on the failure of the joints. The adherent and adhesive used for T-joint are 304 L stainless steel and Hysol E 214 HP with the adhesive thickness of 1.0 mm. The tensile test of the bulk specimen and adhesively T-joint were conducted by using a universal testing machine (UTM) at room temperature (RT), 55 °C, 75 °C, 100 °C and 120 °C, respectively. It was found that as the temperature increases, the failure force strength decreases for bulk and T-joint specimen. Data obtained from the tests at 120 °C showed the failure force of the bulk adhesive decreased by approximately 44 % compared to the specimen tested at RT. Next, the bulk of Hysol failure force result was compared with Araldite at RT and 100 °C. Araldite data was taken from the previous study [1]. It has also been found that the bulk for Hysol has higher failure force compared to Araldite at RT and 100 °C.

Imprinting bulk amorphous alloy at room temperature

DOE PAGES

Kim, Song-Yi; Park, Eun-Soo; Ott, Ryan T.; ...

2015-11-13

We present investigations on the plastic deformation behavior of a brittle bulk amorphous alloy by simple uniaxial compressive loading at room temperature. A patterning is possible by cold-plastic forming of the typically brittle Hf-based bulk amorphous alloy through controlling homogenous flow without the need for thermal energy or shaping at elevated temperatures. The experimental evidence suggests that there is an inconsistency between macroscopic plasticity and deformability of an amorphous alloy. Moreover, imprinting of specific geometrical features on Cu foil and Zr-based metallic glass is represented by using the patterned bulk amorphous alloy as a die. These results demonstrate the abilitymore » of amorphous alloys or metallic glasses to precisely replicate patterning features onto both conventional metals and the other amorphous alloys. In conclusion, our work presents an avenue for avoiding the embrittlement of amorphous alloys associated with thermoplastic forming and yields new insight the forming application of bulk amorphous alloys at room temperature without using heat treatment.« less

High-resolution nuclear magnetic resonance of superfluid 3B

NASA Astrophysics Data System (ADS)

Kycia, J. B.; Haard, T. M.; Rand, M. R.; Hensley, H. H.; Moores, G. F.; Lee, Y.; Hamot, P. J.; Sprague, D. T.; Halperin, W. P.; Thuneberg, E. V.

1994-02-01

High-resolution nuclear magnetic resonance measurements of bulk superfluid 3B have been performed at temperatures above 0.5 mK and at pressures from 0.3 to 21.7 bars. We have found that the resonance frequency is shifted from the Larmor frequency of the normal fluid. According to the theory of Greaves the shift at the superfluid transition determines a specific combination, β345, of the 5 fourth-order coefficients of the order parameter invariants used in the Ginzburg-Landau description of superfluid 3He. We found that β345 approaches the weak coupling limit at low pressure, and decreases at higher pressures qualitatively consistent with the theory of Sauls and Serene but in disagreement with the results of Tang et al.

Fluid channeling system

NASA Technical Reports Server (NTRS)

Davis, Donald Y. (Inventor); Hitch, Bradley D. (Inventor)

1994-01-01

A fluid channeling system includes a fluid ejector, a heat exchanger, and a fluid pump disposed in series flow communication The ejector includes a primary inlet for receiving a primary fluid, and a secondary inlet for receiving a secondary fluid which is mixed with the primary fluid and discharged therefrom as ejector discharge. Heat is removed from the ejector discharge in the heat exchanger, and the heat exchanger discharge is compressed in the fluid pump and channeled to the ejector secondary inlet as the secondary fluid In an exemplary embodiment, the temperature of the primary fluid is greater than the maximum operating temperature of a fluid motor powering the fluid pump using a portion of the ejector discharge, with the secondary fluid being mixed with the primary fluid so that the ejector discharge temperature is equal to about the maximum operating temperature of the fluid motor.

Natural convection heat transfer in water near its density maximum

NASA Astrophysics Data System (ADS)

Yen, Yin-Chao

1990-12-01

This monograph reviews and summarizes to date the experimental and analytical results on the effect of water density near its maximum convection, transient flow and temperature structure characteristics: (1) in a vertical enclosure; (2) in a vertical annulus; (3) between horizontal concentric cylinders; (4) in a square enclosure; (5) in a rectangular enclosure; (6) in a horizontal layer; (7) in a circular confined melt layer; and (8) in bulk water during melting. In a layer of water containing a maximum density temperature of 4 C, the onset of convection (the critical number) is found not to be a constant value as in the classical normal fluid but one that varies with the imposed thermal and hydrodynamic boundaries. In horizontal layers, a nearly constant temperature zone forms and continuously expands between the warm and cold boundaries. A minimum heat transfer exists in most of the geometries studied and, in most cases, can be expressed in terms of a density distribution parameter. The effect of this parameter on a cells formation, disappearance and transient structure is discussed, and the effect of split boundary flow on heat transfer is presented.

Venous compliance and fluid shift measurements on Spacelab IML-1

NASA Technical Reports Server (NTRS)

Leiski, D.; Thirsk, R. B.; Charles, J. B.; Bennett, B.

1992-01-01

During the first few hours of a human spaceflight mission, a headward fluid shift out of the abdomen, pelvis, and legs initiates a number of adaptive cardiovascular responses, including a loss of intravascular and extravascular fluid volume. On return to earth, these cardiovascular changes may lead to debilitating symptoms of orthostatic intolerance in an unprotected astronaut. To test the hypothesis that an inflight increase in compliance of the leg veins may contribute to this condition, measurements of lower leg fluid shift and bulk venous compliance were collected from crew members during the eight-day First International Microgravity Laboratory shuttle mission. An ultrasonic limb plethysmograph, in conjunction with two compression cuffs encircling the calf and thigh, was used to determine bulk compliance of the underlying veins over a range of negative and positive transmural pressures. The data from inflight experiment sessions were compared to preflight and postflight sessions. The preliminary results indicate that the volume of the lower leg decreased by over 10 percent by the sixth day of flight, but there was no apparent change in venous compliance.

Smectite diagenesis, pore-water freshening, and fluid flow at the toe of the Nankai wedge

USGS Publications Warehouse

Brown, K.M.; Saffer, D.M.; Bekins, B.A.

2001-01-01

The presence of low-chloride fluids in the lowermost sediments drilled at Ocean Drilling Program Site 808, at the Nankai accretionary wedge, has been considered as prime evidence for long-distance, lateral fluid flow from depth. Here, we re-evaluate the potential role of in situ reaction of smectite (S) to illite (I) in the genesis of this low chloride anomaly. This reaction is known to be occurring at Site 808, with both the S content and S to I ratio in the mixed layer clays decreasing substantially with depth. We show that the bulk of the chloride anomaly can generate by in situ clay dehydration, particularly if pre-reaction smectite abundances (Ai) approach ?? 10-15% of the bulk sediment. The Ai values, however, are not well constrained. At Ai values < 10-15%, an additional source of low-Cl fluid centered close to the de??collement could be required. Thus, there remains the important possibility that the observed low-Cl anomaly is a compound effect of both lateral flow and in situ smectite dehydration. ?? 2001 Elsevier Science B.V. All rights reserved.

Numerical simulations of internal wave generation by convection in water.

PubMed

Lecoanet, Daniel; Le Bars, Michael; Burns, Keaton J; Vasil, Geoffrey M; Brown, Benjamin P; Quataert, Eliot; Oishi, Jeffrey S

2015-06-01

Water's density maximum at 4°C makes it well suited to study internal gravity wave excitation by convection: an increasing temperature profile is unstable to convection below 4°C, but stably stratified above 4°C. We present numerical simulations of a waterlike fluid near its density maximum in a two-dimensional domain. We successfully model the damping of waves in the simulations using linear theory, provided we do not take the weak damping limit typically used in the literature. To isolate the physical mechanism exciting internal waves, we use the spectral code dedalus to run several simplified model simulations of our more detailed simulation. We use data from the full simulation as source terms in two simplified models of internal-wave excitation by convection: bulk excitation by convective Reynolds stresses, and interface forcing via the mechanical oscillator effect. We find excellent agreement between the waves generated in the full simulation and the simplified simulation implementing the bulk excitation mechanism. The interface forcing simulations overexcite high-frequency waves because they assume the excitation is by the "impulsive" penetration of plumes, which spreads energy to high frequencies. However, we find that the real excitation is instead by the "sweeping" motion of plumes parallel to the interface. Our results imply that the bulk excitation mechanism is a very accurate heuristic for internal-wave generation by convection.

Three-temperature plasma shock solutions with gray radiation diffusion

DOE PAGES

Johnson, Bryan M.; Klein, Richard I.

2016-04-19

Here we discuss the effects of radiation on the structure of shocks in a fully ionized plasma are investigated by solving the steady-state fluid equations for ions, electrons, and radiation. The electrons and ions are assumed to have the same bulk velocity but separate temperatures, and the radiation is modeled with the gray diffusion approximation. Both electron and ion conduction are included, as well as ion viscosity. When the material is optically thin, three-temperature behavior occurs. When the diffusive flux of radiation is important but radiation pressure is not, two-temperature behavior occurs, with the electrons strongly coupled to the radiation.more » Since the radiation heats the electrons on length scales that are much longer than the electron–ion Coulomb coupling length scale, these solutions resemble radiative shock solutions rather than plasma shock solutions that neglect radiation. When radiation pressure is important, all three components are strongly coupled. Results with constant values for the transport and coupling coefficients are compared to a full numerical simulation with a good match between the two, demonstrating that steady shock solutions constitute a straightforward and comprehensive verification test methodology for multi-physics numerical algorithms.« less

Three-temperature plasma shock solutions with gray radiation diffusion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Bryan M.; Klein, Richard I.

Here we discuss the effects of radiation on the structure of shocks in a fully ionized plasma are investigated by solving the steady-state fluid equations for ions, electrons, and radiation. The electrons and ions are assumed to have the same bulk velocity but separate temperatures, and the radiation is modeled with the gray diffusion approximation. Both electron and ion conduction are included, as well as ion viscosity. When the material is optically thin, three-temperature behavior occurs. When the diffusive flux of radiation is important but radiation pressure is not, two-temperature behavior occurs, with the electrons strongly coupled to the radiation.more » Since the radiation heats the electrons on length scales that are much longer than the electron–ion Coulomb coupling length scale, these solutions resemble radiative shock solutions rather than plasma shock solutions that neglect radiation. When radiation pressure is important, all three components are strongly coupled. Results with constant values for the transport and coupling coefficients are compared to a full numerical simulation with a good match between the two, demonstrating that steady shock solutions constitute a straightforward and comprehensive verification test methodology for multi-physics numerical algorithms.« less

Degradation Behavior of the HTS Bulk Magnet in Cryocooler System with Cyclic Temperature Variation

NASA Astrophysics Data System (ADS)

Okuno, K.; Sawa, K.; Iwasa, Y.

2006-03-01

This paper presents a change of magnetic flux trapped in the YBCO bulk magnet under thermal excursions. We have supposed a new cryocooler system for the high temperature superconducting(HTS) bulk magnet in which the thermal cycles are generated. From the past research, it was found that the trapped flux mainly deteriorated at the first temperature rise, but a large change of the trapped flux was not seen at the first temperature descent and following thermal cycles. Degradation of the trapped flux by the first temperature-rise was explained by using the bean model. Moreover we proposed the model which does not have a current distribution constant. In this paper, we examined a change of magnetic field in each part of the bulk in detail. In addition, we applied attention to the change of the trapped flux after the first temperature rise. Although there is no big change of the trapped flux after the first temperature-rise, it is decreasing slowly. This cause is considered as influence of the flux creep, but its decay is more rapid than usual.

Static analysis of a sonar dome rubber window

NASA Technical Reports Server (NTRS)

Lai, J. L.

1978-01-01

The application of NASTRAN (level 16.0.1) to the static analysis of a sonar dome rubber window (SDRW) was demonstrated. The assessment of the conventional model (neglecting the enclosed fluid) for the stress analysis of the SDRW was made by comparing its results to those based on a sophisticated model (including the enclosed fluid). The fluid was modeled with isoparametric linear hexahedron elements with approximate material properties whose shear modulus was much smaller than its bulk modulus. The effect of the chosen material property for the fluid is discussed.

Fluid Dynamics for Physicists

NASA Astrophysics Data System (ADS)

Faber, T. E.

1995-08-01

This textbook provides an accessible and comprehensive account of fluid dynamics that emphasizes fundamental physical principles and stresses connections with other branches of physics. Beginning with a basic introduction, the book goes on to cover many topics not typically treated in texts, such as compressible flow and shock waves, sound attenuation and bulk viscosity, solitary waves and ship waves, thermal convection, instabilities, turbulence, and the behavior of anisotropic, non-Newtonian and quantum fluids. Undergraduate or graduate students in physics or engineering who are taking courses in fluid dynamics will find this book invaluable.

Numerical investigations on the characteristics of thermomagnetic instability in MgB2 bulks

NASA Astrophysics Data System (ADS)

Xia, Jing; Li, Maosheng; Zhou, Youhe

2017-07-01

This paper presents the characteristics of thermomagnetic instability in MgB2 bulks by numerically solving the macroscopic dynamics of thermomagnetic interaction governed by the coupled magnetic and heat diffusion equations in association with a modified E-J power-law relationship. The finite element method is used to discretize the system of partial differential equations. The calculated magnetization loops with flux jumps are consistent with the experimental results for MgB2 slabs bathed in a wide range of ambient temperatures. We reveal the evolution process of the thermomagnetic instability and present the distributions of the magnetic field, temperature, and current density before and after flux jumps. A 2D axisymmetric model is used to study the thermomagnetic instability in cylindrical MgB2 bulks. It is found that the number of flux jumps monotonously reduces as the ambient temperature rises and no flux jump appears when the ambient temperature exceeds a certain value. Moreover, the flux-jump phenomenon exists in a wide range of the ramp rate of the applied external field, i.e. 10-2-102 T s-1. Furthermore, the dependences of the first flux-jump field on the ambient temperature, ramp rate, and bulk thickness are investigated. The critical bulk thicknesses for stability are obtained for different ambient temperatures and sample radii. In addition, the influence of the capability of the interfacial heat transfer on the temporal response of the bulk temperature is discussed. We also find that the prediction of thermomagnetic instability is sensitive to the employment of the flux creep exponent in the simulations.

Method for net-shaping using aerogels

DOEpatents

Brinker, C. Jeffrey; Ashey, Carol S.; Reed, Scott T.; Sriram, Chunangad S.; Harris, Thomas M.

2001-01-01

A method of net-shaping using aerogel materials is provided by first forming a sol, aging the sol to form a gel, with the gel having a fluid component and having been formed into a medium selected from the group consisting of a powder, bulk material, or granular aerobeads, derivatizing the surface of the gel to render the surface unreactive toward further condensation, removing a portion of the fluid component of the final shaped gel to form a partially dried medium, placing the medium into a cavity, wherein the volume of said medium is less that the volume of the cavity, and removing a portion of the fluid component of the medium. The removal, such as by heating at a temperature of approximately less than 50.degree. C., applying a vacuum, or both, causes the volume of the medium to increase and to form a solid aerogel. The material can be easily removed by exposing the material to a solvent, thereby reducing the volume of the material. In another embodiment, the gel is derivatized and then formed into a shaped medium, where subsequent drying reduces the volume of the shaped medium, forming a net-shaping material. Upon further drying, the material increases in volume to fill a cavity. The present invention is both a method of net-shaping and the material produced by the method.

Prediction of the rate of the rise of an air bubble in nanofluids in a vertical tube.

PubMed

Cho, Heon Ki; Nikolov, Alex D; Wasan, Darsh T

2018-04-19

Our recent experiments have demonstrated that when a bubble rises through a nanofluid (a liquid containing dispersed nanoparticles) in a vertical tube, a nanofluidic film with several particle layers is formed between the gas bubble and the glass tube wall, which significantly changes the bubble velocity due to the nanoparticle layering phenomenon in the film. We calculated the structural nanofilm viscosity as a function of the number of particle layers confined in it and found that the film viscosity increases rather steeply when the film contains only one or two particle layers. The nanofilm viscosity was found to be several times higher than the bulk viscosity of the fluid. Consequently, the Bretherton equation cannot accurately predict the rate of the rise of a slow-moving long bubble in a vertical tube in a nanofluid because it is valid only for very thick films and uses the bulk viscosity of the fluid. However, in this brief note, we demonstrate that the Bretherton equation can indeed be used for predicting the rate of the rise of a long single bubble through a vertical tube filled with a nanofluid by simply replacing the bulk viscosity with the proper structural nanofilm viscosity of the fluid. Copyright © 2018. Published by Elsevier Inc.

Simultaneous Rheoelectric Measurements of Strongly Conductive Complex Fluids

NASA Astrophysics Data System (ADS)

Helal, Ahmed; Divoux, Thibaut; McKinley, Gareth H.

2016-12-01

We introduce an modular fixture designed for stress-controlled rheometers to perform simultaneous rheological and electrical measurements on strongly conductive complex fluids under shear. By means of a nontoxic liquid metal at room temperature, the electrical connection to the rotating shaft is completed with minimal additional mechanical friction, allowing for simultaneous stress measurements at values as low as 1 Pa. Motivated by applications such as flow batteries, we use the capabilities of this design to perform an extensive set of rheoelectric experiments on gels formulated from attractive carbon-black particles, at concentrations ranging from 4 to 15 wt %. First, experiments on gels at rest prepared with different shear histories show a robust power-law scaling between the elastic modulus G0' and the conductivity σ0 of the gels—i.e., G0'˜σ0α, with α =1.65 ±0.04 , regardless of the gel concentration. Second, we report conductivity measurements performed simultaneously with creep experiments. Changes in conductivity in the early stage of the experiments, also known as the Andrade-creep regime, reveal for the first time that plastic events take place in the bulk, while the shear rate γ ˙ decreases as a weak power law of time. The subsequent evolution of the conductivity and the shear rate allows us to propose a local yielding scenario that is in agreement with previous velocimetry measurements. Finally, to establish a set of benchmark data, we determine the constitutive rheological and electrical behavior of carbon-black gels. Corrections first introduced for mechanical measurements regarding shear inhomogeneity and wall slip are carefully extended to electrical measurements to accurately distinguish between bulk and surface contributions to the conductivity. As an illustrative example, we examine the constitutive rheoelectric properties of five different grades of carbon-black gels and we demonstrate the relevance of this rheoelectric apparatus as a versatile characterization tool for strongly conductive complex fluids and their applications.

Thermal treatment induced modification of structural, surface and bulk magnetic properties of Fe61.5Co5Ni8Si13.5B9Nb3 metallic glass

NASA Astrophysics Data System (ADS)

Shah, M.; Satalkar, M.; Kane, S. N.; Ghodke, N. L.; Sinha, A. K.; Varga, L. K.; Teixeira, J. M.; Araujo, J. P.

2018-05-01

Effect of thermal annealing induced modification of structural, surface and bulk magnetic properties of Fe61.5Co5Ni8Si13.5B9Nb3 alloy is presented. The changes in properties were observed using synchrotron x-ray diffraction technique (SXRD), atomic force microscopy (AFM), magneto-optical kerr effect (MOKE) and bulk magnetic measurements. Significant variations on the both side of surface occur for the annealing temperature upto 500 °C promotes the surface crystallization. Surface roughness appears due to presence of nanocrystallization plays an important role in determining magnetic properties. Observed lower value of bulk coercivity Hc of 6.2 A/m annealed temperature at 450 °C/1 h ascribed to reduction of disorder as compared to the surface (both shiny and wheel side observed by MOKE measurement) whereas improvement of bulk saturation magnetization with annealing temperature indicates first near neighbor shell of Fe atoms are surrounded by Fe atoms. Evolution of coercivity of surface and bulk with annealing temperature has been presented in conjunction with the structural observations.

The role of bulk viscosity on the decay of compressible, homogeneous, isotropic turbulence

NASA Astrophysics Data System (ADS)

Johnsen, Eric; Pan, Shaowu

2016-11-01

The practice of neglecting bulk viscosity in studies of compressible turbulence is widespread. While exact for monatomic gases and unlikely to strongly affect the dynamics of fluids whose bulk-to-shear viscosity ratio is small and/or of weakly compressible turbulence, this assumption is not justifiable for compressible, turbulent flows of gases whose bulk viscosity is orders of magnitude larger than their shear viscosities (e.g., CO2). To understand the mechanisms by which bulk viscosity and the associated phenomena affect compressible turbulence, we conduct DNS of freely decaying compressible, homogeneous, isotropic turbulence for ratios of bulk-to-shear viscosity ranging from 0-1000. Our simulations demonstrate that bulk viscosity increases the decay rate of turbulent kinetic energy; while enstrophy exhibits little sensitivity to bulk viscosity, dilatation is reduced by an order of magnitude within the two eddy turnover time. Via a Helmholtz decomposition of the flow, we determined that bulk viscosity damps the dilatational velocity and reduces dilatational-solenoidal exchanges, as well as pressure-dilatation coupling. In short, bulk viscosity renders compressible turbulence incompressible by reducing energy transfer between translational and internal modes.

Bulk Viscosity of Bubbly Magmas and the Amplification of Pressure Waves

NASA Astrophysics Data System (ADS)

Navon, O.; Lensky, N. G.; Neuberg, J. W.; Lyakhovsky, V.

2001-12-01

The bulk viscosity of magma is needed in order to describe the dynamics of a compressible bubbly magma flowing in conduits and to follow the attenuation of pressure waves travelling through a compressible magma. We developed a model for the bulk viscosity of a suspension of gas bubbles in an incompressible Newtonian liquid that exsolves volatiles (e.g. magma). The suspension is modeled as a close pack of spherical cells, consisting of gas bubbles centered in spherical shells of a volatile-bearing liquid. Following a drop in the ambient pressure the resulting dilatational motion and driving pressure are obtained in terms of the two-phase cell parameters, i.e. bubble radius and gas pressure. By definition, the bulk viscosity of a fluid is the relation between changes of the driving pressure with respect to changes in the resulted expansion strain-rate. Thus, we can use the two-phase solution to define the bulk viscosity of a hypothetical cell, composed of a homogeneously compressible, one-phase, continuous fluid. The resulted bulk viscosity is highly non-linear. At the beginning of the expansion process, when gas exsolution is efficient, the expansion rate grows exponentially while the driving pressure decreases slightly. That means that bulk viscosity is formally negative. The negative value reflects the release of the energy stored in the supersaturated liquid (melt) and its conversion to mechanical work during exsolution. Later, when bubbles are large enough and the gas influx decreases significantly, the strain rate decelerates and the bulk viscosity becomes positive as expected in a dissipative system. We demonstrate that amplification of seismic wave travelling through a volcanic conduit filled with a volatile saturated magma may be attributed to the negative bulk viscosity of the compressible magma. Amplification of an expansion wave may, at some level in the conduit, damage the conduit walls and initiate opening of new pathways for magma to erupt.

Temperature Control in a Franz Diffusion Cell Skin Sonoporation Setup

NASA Astrophysics Data System (ADS)

Robertson, Jeremy; Becker, Sid

2017-11-01

In vitro experimental studies that investigate ultrasound enhanced transdermal drug delivery employ Franz diffusion cells. Because of absorption, the temperature of the coupling fluid often increases drastically during the ultrasound application. The current methodologies for controlling the coupling fluid temperature require either replacement of the coupling fluid during the experiment or the application of a time consuming duty cycle. This paper introduces a novel method for temperature control that allows for a wide variety of coupling fluid temperatures to be maintained. This method employs a peristaltic pump to circulate the coupling fluid through a thermoelectric cooling device. This temperature control method allowed for an investigation into the role of coupling fluid temperature on the inertial cavitation that impacts the skin aperture (inertial cavitation is thought to be the main cause of ultrasound induced skin permeability increase). Both foil pitting and passive cavitation detection experiments indicated that effective inertial cavitation activity decreases with increasing coupling fluid temperature. This finding suggests that greater skin permeability enhancement can be achieved if a lower coupling fluid temperature is maintained during skin insonation.

Experimental study of the replacement of calcite by calcium sulphates

NASA Astrophysics Data System (ADS)

Ruiz-Agudo, E.; Putnis, C. V.; Hövelmann, J.; Álvarez-Lloret, P.; Ibáñez-Velasco, A.; Putnis, A.

2015-05-01

Among the most relevant mineral replacement reactions are those involving sulphates and carbonates, which have important geological and technological implications. Here it is shown experimentally that during the interaction of calcite (CaCO3) cleavage surfaces with sulphate-bearing acidic solutions, calcite is ultimately replaced by gypsum (CaSO4 2H2O) and anhydrite (CaSO4), depending on the reaction temperature. Observations suggest that this occurs most likely via an interface-coupled dissolution-precipitation reaction, in which the substrate is replaced pseudomorphically by the product. At 120 and 200 °C gypsum and/or bassanite (CaSO4·0.5H2O) form as precursor phases for the thermodynamically stable anhydrite. Salinity promotes the formation of less hydrated precursor phases during the replacement of calcite by anhydrite. The reaction stops before equilibrium with respect to calcite is reached and during the course of the reaction most of the bulk solutions are undersaturated with respect to the precipitating phase(s). A mechanism consisting of the dissolution of small amounts of solid in a thin layer of fluid at the mineral-fluid interface and the subsequent precipitation of the product phase from this layer is in agreement with these observations. PHREEQC simulations performed in the framework of this mechanism highlight the relevance of transport and surface reaction kinetics on the volume change associated with the CaCO3-CaSO4 replacement. Under our experimental conditions, this reaction occurs with a positive volume change, which ultimately results in passivation of the unreacted substrate before calcite attains equilibrium with respect to the bulk solution.

Genesis of the Abu Marawat gold deposit, central Eastern Desert of Egypt

NASA Astrophysics Data System (ADS)

Zoheir, Basem A.; Akawy, Ahmed

2010-06-01

Gold mineralisation at the Abu Marawat mine, central Eastern Desert of Egypt, is related to a system of massive and sheared, milky quartz veins cutting a sequence of Neoproterozoic island arc metavolcanic/volcaniclastic rocks and related banded iron formation (BIF). Sulphide-bearing quartz veins and related hydrothermal breccia bodies display a range of textures including sheared, boudinaged and recrystallised quartz, open space filling and microbreccia. These variable textures imply a complex history of crack-seal mechanism characterising the relation between mineral deposition and a major N-S-trending shear zone, during a late brittle-ductile deformation event which affected the area at about 550 Ma. Gold-base metal mineralisation is associated with brecciation and fracturing of the iron ore bands, close to silicified shears and related quartz veins. The auriferous quartz lodes are characterised by the occurrence of visible pyrite-chalcopyrite ± pyrrhotite ± sphalerite ± galena mineralisation. Gold is refractory in pyrite and chalcopyrite, but rare visible gold/electrum and telluride specks were observed in a few samples. Hydrothermal alteration includes pervasive silicification, pyritisation, sericitisation, carbonatisation confined to a delicate set of veins and altered shears, and a more widespread propylitic alteration assemblage (quartz + chlorite + pyrite + calcite ± epidote). Fluid inclusion petrography and microthermometric studies suggest heterogeneous trapping of a low-salinity (1.4-6.7 wt.% eq. NaCl) aqueous solution and a carbonic fluid. Evidence for fluid immiscibility during ore formation includes variable liquid/vapour ratios in inclusions along individual trails and bulk inclusion homogenisation into liquid and occasionally to vapour at comparable temperatures. The trapping conditions of intragranular aqueous-carbonic inclusions approximate 264-378 °C at 700-1300 bar. Similar temperature estimates have been obtained from Al-in-chlorite geothermometry of chlorite associated with sulphides in the mineralised quartz veins. Fracturing enhanced fluid circulation through the wallrock and related BIF, allowing reaction of the S-bearing ore fluid with iron oxides. This caused pyrite formation and concomitant Au precipitation, enhanced by fluid immiscibility as H 2S partitioned preferentially into the carbonic phase. The ore fluids may have originated from granitoid intrusions (likely the post-Hammamat felsites, whereas gold and base metals might have been leached from the Abu Marawat basic metavolcanics.

The Gassmann-Burgers Model to Simulate Seismic Waves at the Earth Crust And Mantle

NASA Astrophysics Data System (ADS)

Carcione, José M.; Poletto, Flavio; Farina, Biancamaria; Craglietto, Aronne

2017-03-01

The upper part of the crust shows generally brittle behaviour while deeper zones, including the mantle, may present ductile behaviour, depending on the pressure-temperature conditions; moreover, some parts are melted. Seismic waves can be used to detect these conditions on the basis of reflection and transmission events. Basically, from the elastic-plastic point of view the seismic properties (seismic velocity and density) depend on effective pressure and temperature. Confining and pore pressures have opposite effects on these properties, such that very small effective pressures (the presence of overpressured fluids) may substantially decrease the P- and S-wave velocities, mainly the latter, by opening of cracks and weakening of grain contacts. Similarly, high temperatures induce the same effect by partial melting. To model these effects, we consider a poro-viscoelastic model based on Gassmann equations and Burgers mechanical model to represent the properties of the rock frame and describe ductility in which deformation takes place by shear plastic flow. The Burgers elements allow us to model the effects of seismic attenuation, velocity dispersion and steady-state creep flow, respectively. The stiffness components of the brittle and ductile media depend on stress and temperature through the shear viscosity, which is obtained by the Arrhenius equation and the octahedral stress criterion. Effective pressure effects are taken into account in the dry-rock moduli using exponential functions whose parameters are obtained by fitting experimental data as a function of confining pressure. Since fluid effects are important, the density and bulk modulus of the saturating fluids (water and steam) are modeled using the equations provided by the NIST website, including supercritical behaviour. The theory allows us to obtain the phase velocity and quality factor as a function of depth and geological pressure and temperature as well as time frequency. We then obtain the PS and SH equations of motion recast in the velocity-stress formulation, including memory variables to avoid the computation of time convolutions. The equations correspond to isotropic anelastic and inhomogeneous media and are solved by a direct grid method based on the Runge-Kutta time stepping technique and the Fourier pseudospectral method. The algorithm is tested with success against known analytical solutions for different shear viscosities. An example shows how anomalous conditions of pressure and temperature can in principle be detected with seismic waves.

The surface stability of Cr 2O 3 (0 0 0 1)

DOE PAGES

Cao, Shi; Wu, Ning; Echtenkamp, William; ...

2015-05-28

The surface of chromia (Cr 2O 3) has a surface electronic structure distinct from the bulk and a packing density distinct from the bulk. More than a demarcation between the solid and the vacuum, the surface differs from the bulk of chromia, not just because of a partial occupancy of chromium sites, but also because of an increased number of unoccupied surface oxygen sites (vacancy sites), evident in angle-resolved core level photoemission. In spite of the structural differences that exist at the surface, there is, as yet, no evidence that these complications affect the surface Debye temperature beyond the mostmore » simple of assumptions regarding the lower coordination of the surface. Using low-energy electron diffraction (LEED), the effective surface Debye temperature (similar to 490 K) is found to be lower than the bulk (similar to 645 K) Debye temperature of Cr 2O 3(0 0 0 1). This surface effective Debye temperature, indicative of vibrations along the surface normal, uncorrected for anharmonic effects, has a value reduced from the effective bulk Debye temperature yet close to the value root 2 expected from a simple mean field argument.« less

Direct and indirect measurement of the magnetocaloric effect in bulk and nanostructured Ni-Mn-In Heusler alloy

NASA Astrophysics Data System (ADS)

Ghahremani, Mohammadreza; Aslani, Amir; Hosseinnia, Marjan; Bennett, Lawrence H.; Della Torre, Edward

2018-05-01

A systematic study of the magnetocaloric effect of a Ni51Mn33.4In15.6 Heusler alloy converted to nanoparticles via high energy ball-milling technique in the temperature range of 270 to 310 K has been performed. The properties of the particles were characterized by x-ray diffraction, electron microscopy, and magnetometer techniques. Isothermal magnetic field variation of magnetization exhibits field hysteresis in bulk Ni51Mn33.4In15.6 alloy across the martensitic transition which significantly lessened in the nanoparticles. The magnetocaloric effects of the bulk and nanoparticle samples were measured both with direct method, through our state of the art direct test bed apparatus with controllability over the applied fields and temperatures, as well as an indirect method through Maxwell and thermodynamic equations. In direct measurements, nanoparticle sample's critical temperature decreased by 6 K, but its magnetocaloric effect enhanced by 17% over the bulk counterpart. Additionally, when comparing the direct and indirect magnetocaloric curves, the direct method showed 14% less adiabatic temperature change in the bulk and 5% less adiabatic temperature change in the nanostructured sample.

Poly-N-acetylglucosamine matrix polysaccharide impedes fluid convection and transport of the cationic surfactant cetylpyridinium chloride through bacterial biofilms.

PubMed

Ganeshnarayan, Krishnaraj; Shah, Suhagi M; Libera, Matthew R; Santostefano, Anthony; Kaplan, Jeffrey B

2009-03-01

Biofilms are composed of bacterial cells encased in a self-synthesized, extracellular polymeric matrix. Poly-beta(1,6)-N-acetyl-d-glucosamine (PNAG) is a major biofilm matrix component in phylogenetically diverse bacteria. In this study we investigated the physical and chemical properties of the PNAG matrix in biofilms produced in vitro by the gram-negative porcine respiratory pathogen Actinobacillus pleuropneumoniae and the gram-positive device-associated pathogen Staphylococcus epidermidis. The effect of PNAG on bulk fluid flow was determined by measuring the rate of fluid convection through biofilms cultured in centrifugal filter devices. The rate of fluid convection was significantly higher in biofilms cultured in the presence of the PNAG-degrading enzyme dispersin B than in biofilms cultured without the enzyme, indicating that PNAG decreases bulk fluid flow. PNAG also blocked transport of the quaternary ammonium compound cetylpyridinium chloride (CPC) through the biofilms. Binding of CPC to biofilms further impeded fluid convection and blocked transport of the azo dye Allura red. Bioactive CPC was efficiently eluted from biofilms by treatment with 1 M sodium chloride. Taken together, these findings suggest that CPC reacts directly with the PNAG matrix and alters its physical and chemical properties. Our results indicate that PNAG plays an important role in controlling the physiological state of biofilms and may contribute to additional biofilm-associated processes such as biocide resistance.

Modern high powered led curing lights and their effect on pulp chamber temperature of bulk and incrementally cured composite resin.

PubMed

Oberholzer, T G; Makofane, M E; du Preez, I C; George, R

2012-06-01

Pulpal temperature changes induced by modern high powered light emitting diodes (LEDs) are of concern when used to cure composite resins. This study showed an increase in pulp chamber temperature with an increase in power density for all light cure units (LCU) when used to bulk cure composite resin. Amongst the three LEDs tested, the Elipar Freelight-2 recorded the highest temperature changes. Bulk curing recorded a significantly larger rise in pulp chamber temperature change than incrementally cured resin for all light types except for the Smartligh PS. Both the high powered LED and the conventional curing units can generate heat. Though this temperature rise may not be sufficient to cause irreversible pulpal damage, it would be safer to incrementally cure resins.

The role of zonal flows in reactive fluid closures

NASA Astrophysics Data System (ADS)

Jan, WEILAND

2018-07-01

We will give an overview of results obtained by our reactive fluid model. It is characterised as a fluid model where all moments with sources in the experiment are kept. Furthermore, full account is taken for the highest moments appearing in unexpanded denominators also including full toroidicity. It has been demonstrated that the strength of zonal flows is dramatically larger in reactive fluid closures than in those which involve dissipation. This gives a direct connection between the fluid closure and the level of excitation of turbulence. This is because zonal flows are needed to absorb the inverse cascade in quasi 2D turbulence. This also explains the similarity in structure of the transport coefficients in our model with a reactive closure in the energy equation and models which have a reactive closure because of zero ion temperature such as the Hasegawa–Wakatani model. Our exact reactive closure unifies several well-known features of tokamak experiments such as the L–H transition, internal transport barriers and the nonlinear Dimits upshift of the critical gradient for onset of transport. It also gives transport of the same level as that in nonlinear gyrokinetic codes. Since these include the kinetic resonance this confirms the validity of the thermodynamic properties of our model. Furthermore, we can show that while a strongly nonlinear model is needed in kinetic theory a quasilinear model is sufficient in the fluid description. Thus our quasilinear fluid model will be adequate for treating all relevant problems in bulk transport. This is finally confirmed by the reproduction by the model of the experimental power scaling of the confinement time τ E ∼ P ‑2/3. This confirms the validity of our reactive fluid model. This also gives credibility to our ITER simulations including the H-mode barrier. A new result is here, that alpha heating strongly reduces the slope of the H-mode barrier. This should significantly reduce the effects of ELM’s.

Nanoscale Pore Features and Associated Fluid Behavior in Shale

NASA Astrophysics Data System (ADS)

Cole, D. R.; Striolo, A.

2017-12-01

Unconventional hydrocarbons occurring in economic abundance require greater than industry-standard levels of technology or investment to exploit. Geological formations that host unconventional oil and gas are extraordinarily heterogeneous and exhibit a wide range of physical and chemical features that can vary over many orders of magnitude in length scale. The size, distribution and connectivity of these confined geometries, the chemistry of the solid, the chemistry of the fluids and their physical properties collectively dictate how fluids migrate into and through these micro- and nano-environments, wet and ultimately react with the solid surfaces. Our current understanding of the rates and mechanisms of fluid and mass transport and interaction within these multiporosity systems at the molecular scale is far less robust than we would like. This presentation will take a two-fold approach to this topic area. First, a brief overview is provided that highlights the use of advanced electron microscopy and neutrons scattering methods to quantify the nature of the nanopore system that hosts hydrocarbons in representative gas shale formations such as the Utica, Marcellus and Eagle Ford. Second, results will be presented that leverage the application of state-of-the-art experimental, analytical and computational tools to assess key features of the fluid-matrix interaction relevant to shale settings. The multidisciplinary approaches highlighted will include neutron scattering and NMR experiments, thermodynamic measurements and molecular-level simulations to quantitatively assess molecular properties of C-O-H fluids confined to well-characterized porous media, subjected to temperatures and pressures relevant to subsurface energy systems. These studies conducted in concert are beginning to provide a fundamental understanding at the molecular level of how intrinsically different hydrocarbon-bearing fluids behave in confined geometries compared to bulk systems, and shed light on key geochemical processes such as fluid wetting, competitive sorption and the onset of mineral dissolution and precipitation.

Mineralogical, geochemical and isotopic characteristics of hydrothermal alteration processes in the active, submarine, felsic-hosted PACMANUS field, Manus Basin, Papua New Guinea

NASA Astrophysics Data System (ADS)

Lackschewitz, K. S.; Devey, C. W.; Stoffers, P.; Botz, R.; Eisenhauer, A.; Kummetz, M.; Schmidt, M.; Singer, A.

2004-11-01

During ODP Leg 193, 4 sites were drilled in the active PACMANUS hydrothermal field on the crest of the felsic Pual Ridge to examine the vertical and lateral variations in mineralization and alteration patterns. We present new data on clay mineral assemblages, clay and whole rock chemistry and clay mineral strontium and oxygen isotopic compositions of altered rocks from a site of diffuse low-temperature venting (Snowcap, Site 1188) and a site of high-temperature venting (Roman Ruins, Site 1189) in order to investigate the water-rock reactions and associated elemental exchanges. The volcanic succession at Snowcap has been hydrothermally altered, producing five alteration zones: (1) chlorite ± illite-cristobalite-plagioclase alteration apparently overprinted locally by pyrophyllite bleaching at temperatures of 260-310°C; (2) chlorite ± mixed-layer clay alteration at temperatures of 230°C; (3) chlorite and illite alteration; (4) illite and chlorite ± illite mixed-layer alteration at temperatures of 250-260°C; and (5) illite ± chlorite alteration at 290-300°C. Felsic rocks recovered from two holes (1189A and 1189B) at Roman Ruins, although very close together, show differing alteration features. Hole 1189A is characterized by a uniform chlorite-illite alteration formed at ˜250°C, overprinted by quartz veining at 350°C. In contrast, four alteration zones occur in Hole 1189B: (1) illite ± chlorite alteration formed at ˜300°C; (2) chlorite ± illite alteration at 235°C; (3) chlorite ± illite and mixed layer clay alteration; and (4) chlorite ± illite alteration at 220°C. Mass balance calculations indicate that the chloritization, illitization and bleaching (silica-pyrophyllite assemblages) alteration stages are accompanied by different chemical changes relative to a calculated pristine precursor lava. The element Cr appears to have a general enrichment in the altered samples from PACMANUS. The clay concentrate data show that Cr and Cu are predominantly present in the pyrophyllites. Illite shows a significant enrichment for Cs and Cu relative to the bulk altered samples. Considerations of mineral stability allow us to place some constraints on fluid chemistry. Hydrothermal fluid pH for the chloritization and illitization was neutral to slightly acidic and relatively acidic for the pyrophyllite alteration. In general the fluids, especially from Roman Ruins and at intermediate depths below Snowcap, show only a small proportion of seawater mixing (<10%). Fluids in shallow and deep parts of the Snowcap holes, in contrast, show stronger seawater influence.

Intensive low-temperature tectono-hydrothermal overprint of peraluminous rare-metal granite: a case study from the Dlhá dolina valley (Gemericum, Slovakia)

NASA Astrophysics Data System (ADS)

Breiter, Karel; Broska, Igor; Uher, Pavel

2015-02-01

A unique case of low-temperature metamorphic (hydrothermal) overprint of peraluminous, highly evolved rare-metal S-type granite is described. The hidden Dlhá dolina granite pluton of Permian age (Western Carpathians, eastern Slovakia) is composed of barren biotite granite, mineralized Li-mica granite and albitite. Based on whole-rock chemical data and evaluation of compositional variations of rock-forming and accessory minerals (Rb-P-enriched K-feldspar and albite; biotite, zinnwaldite and di-octahedral micas; Hf-(Sc)-rich zircon, fluorapatite, topaz, schorlitic tourmaline), the following evolutionary scenario is proposed: (1) Intrusion of evolved peraluminous melt enriched in Li, B, P, F, Sn, Nb, Ta, and W took place followed by intrusion of a large body of biotite granites into Paleozoic metapelites and metarhyolite tuffs; (2) The highly evolved melt differentiated in situ forming tourmaline-bearing Li-biotite granite at the bottom, topaz-zinnwaldite granite in the middle, and quartz albitite to albitite at the top of the cupola. The main part of the Sn, Nb, and Ta crystallized from the melt as disseminated cassiterite and Nb-Ta oxide minerals within the albitite, while disseminated wolframite appears mainly within the topaz-zinnwaldite granite. The fluid separated from the last portion of crystallized magma caused small scale greisenization of the albitite; (3) Alpine (Cretaceous) thrusting strongly tectonized and mylonitized the upper part of the pluton. Hydrothermal low-temperature fluids enriched in Ca, Mg, and CO2 unfiltered mechanically damaged granite. This fluid-driven overprint caused formation of carbonate veinlets, alteration and release of phosphorus from crystal lattice of feldspars and Li from micas, precipitating secondary Sr-enriched apatite and Mg-rich micas. Consequently, all bulk-rock and mineral markers were reset and now represent the P-T conditions of the Alpine overprint.

Mechanically Enhanced Liquid Interfaces at Human Body Temperature Using Thermosensitive Methylated Nanocrystalline Cellulose.

PubMed

Scheuble, N; Geue, T; Kuster, S; Adamcik, J; Mezzenga, R; Windhab, E J; Fischer, P

2016-02-09

The mechanical performance of materials at oil/water interfaces after consumption is a key factor affecting hydrophobic drug release. In this study, we methylated the surface of nanocrystalline cellulose (NCC) by mercerization and dimethyl sulfate exposure to produce thermosensitive biopolymers. These methylated NCC (metNCC) were used to investigate interfacial thermogelation at air/water and medium-chain triglyceride (MCT)/water interfaces at body temperature. In contrast to bulk fluid dynamics, elastic layers were formed at room temperature, and elasticity increased significantly at body temperature, which was measured by interfacial shear and dilatational rheology in situ. This unique phenomenon depends on solvent quality, temperature, and polymer concentration at interfaces. Thus, by adjusting the degree of hydrophobicity of metNCC, the interfacial elasticity and thermogelation of the interfaces could be varied. In general, these new materials (metNCC) formed more brittle interfacial layers compared to commercial methylcellulose (MC A15). Thermogelation of methylcellulose promotes attractive intermolecular forces, which were reflected in a change in self-assembly of metNCC at the interface. As a consequence, layer thickness and density increased as a function of temperature. These effects were measured by atomic force microscopy (AFM) images of the displaced interface and confirmed by neutron reflection. The substantial structural and mechanical change of methylcellulose interfaces at body temperature represents a controllable encapsulation parameter allowing optimization of lipid-based drug formulations.

Tuning the heat transfer medium and operating conditions in magnetic refrigeration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghahremani, Mohammadreza, E-mail: mghahrem@shepherd.edu; Dept. of Electrical and Computer Engineering, The George Washington University, Washington DC 20052; Aslani, Amir

A new experimental test bed has been designed, built, and tested to evaluate the effect of the system’s parameters on a reciprocating Active Magnetic Regenerator (AMR) near room temperature. Bulk gadolinium was used as the refrigerant, silicon oil as the heat transfer medium, and a magnetic field of 1.3 T was cycled. This study focuses on the methodology of single stage AMR operation conditions to get a high temperature span near room temperature. Herein, the main objective is not to report the absolute maximum attainable temperature span seen in an AMR system, but rather to find the system’s optimal operatingmore » conditions to reach that maximum span. The results of this research show that there is a optimal operating frequency, heat transfer fluid flow rate, flow duration, and displaced volume ratio in any AMR system. By optimizing these parameters in our AMR apparatus the temperature span between the hot and cold ends increased by 24%. The optimized values are system dependent and need to be determined and measured for any AMR system by following the procedures that are introduced in this research. It is expected that such optimization will permit the design of a more efficient magnetic refrigeration system.« less

7 CFR 1000.42 - Classification of transfers and diversions.

Code of Federal Regulations, 2011 CFR

2011-01-01

.... (a) Transfers and diversions to pool plants. Skim milk or butterfat transferred or diverted in the form of a fluid milk product or transferred in the form of a bulk fluid cream product from a pool plant... corresponding step of § 1000.44(b); (2) If the transferring plant received during the month other source milk to...

Highly resolved fluid flows: "liquid plasmas" at the kinetic level.

PubMed

Morfill, Gregor E; Rubin-Zuzic, Milenko; Rothermel, Hermann; Ivlev, Alexei V; Klumov, Boris A; Thomas, Hubertus M; Konopka, Uwe; Steinberg, Victor

2004-04-30

Fluid flow around an obstacle was observed at the kinetic (individual particle) level using "complex (dusty) plasmas" in their liquid state. These "liquid plasmas" have bulk properties similar to water (e.g., viscosity), and a comparison in terms of similarity parameters suggests that they can provide a unique tool to model classical fluids. This allows us to study "nanofluidics" at the most elementary-the particle-level, including the transition from fluid behavior to purely kinetic transport. In this (first) experimental investigation we describe the kinetic flow topology, discuss our observations in terms of fluid theories, and follow this up with numerical simulations.

Disentangling the surface and bulk electronic structures of LaOFeAs

DOE PAGES

Zhang, P.; Ma, J.; Qian, T.; ...

2016-09-20

We performed a comprehensive angle-resolved photoemission spectroscopy study of the electronic band structure of LaOFeAs single crystals. We found that samples cleaved at low temperature show an unstable and very complicated band structure, whereas samples cleaved at high temperature exhibit a stable and clearer electronic structure. Using in situ surface doping with K and supported by first-principles calculations, we identify both surface and bulk bands. Our assignments are confirmed by the difference in the temperature dependence of the bulk and surface states.

Modeling ARRM Xenon Tank Pressurization Using 1D Thermodynamic and Heat Transfer Equations

NASA Technical Reports Server (NTRS)

Gilligan, Patrick; Tomsik, Thomas

2016-01-01

As a first step in understanding what ground support equipment (GSE) is required to provide external cooling during the loading of 5,000 kg of xenon into 4 aluminum lined composite overwrapped pressure vessels (COPVs), a modeling analysis was performed using Microsoft Excel. The goals of the analysis were to predict xenon temperature and pressure throughout loading at the launch facility, estimate the time required to load one tank, and to get an early estimate of what provisions for cooling xenon might be needed while the tanks are being filled. The model uses the governing thermodynamic and heat transfer equations to achieve these goals. Results indicate that a single tank can be loaded in about 15 hours with reasonable external coolant requirements. The model developed in this study was successfully validated against flight and test data. The first data set is from the Dawn mission which also utilizes solar electric propulsion with xenon propellant, and the second is test data from the rapid loading of a hydrogen cylindrical COPV. The main benefit of this type of model is that the governing physical equations using bulk fluid solid temperatures can provide a quick and accurate estimate of the state of the propellant throughout loading which is much cheaper in terms of computational time and licensing costs than a Computation Fluid Dynamics (CFD) analysis while capturing the majority of the thermodynamics and heat transfer.

Modeling Xenon Tank Pressurization using One-Dimensional Thermodynamic and Heat Transfer Equations

NASA Technical Reports Server (NTRS)

Gilligan, Ryan P.; Tomsik, Thomas M.

2017-01-01

As a first step in understanding what ground support equipment (GSE) is required to provide external cooling during the loading of 5,000 kg of xenon into 4 aluminum lined composite overwrapped pressure vessels (COPVs), a modeling analysis was performed using Microsoft Excel. The goals of the analysis were to predict xenon temperature and pressure throughout loading at the launch facility, estimate the time required to load one tank, and to get an early estimate of what provisions for cooling xenon might be needed while the tanks are being filled. The model uses the governing thermodynamic and heat transfer equations to achieve these goals. Results indicate that a single tank can be loaded in about 15 hours with reasonable external coolant requirements. The model developed in this study was successfully validated against flight and test data. The first data set is from the Dawn mission which also utilizes solar electric propulsion with xenon propellant, and the second is test data from the rapid loading of a hydrogen cylindrical COPV. The main benefit of this type of model is that the governing physical equations using bulk fluid solid temperatures can provide a quick and accurate estimate of the state of the propellant throughout loading which is much cheaper in terms of computational time and licensing costs than a Computation Fluid Dynamics (CFD) analysis while capturing the majority of the thermodynamics and heat transfer.

Role of Confinement on Adsorption and Dynamics of Ethane and an Ethane–CO 2 Mixture in Mesoporous CPG Silica

DOE PAGES

Patankar, Sumant; Gautam, Siddharth; Rother, Gernot; ...

2016-02-10

It was found that ethane is confined to mineral and organic pores in certain shale formations. Effects of confinement on structural and dynamic properties of ethane in mesoporous controlled pore glass (CPG) were studied by gravimetric adsorption and quasi-elastic neutron scattering (QENS) measurements. The obtained isotherms and scattering data complement each other by quantifying the relative strength of the solid–fluid interactions and the transport properties of the fluid under confinement, respectively. We used a magnetic suspension balance to measure the adsorption isotherms at two temperatures and over a range of pressures corresponding to a bulk density range of 0.01–0.35 g/cmmore » 3. Key confinement effects were highlighted through differences between isotherms for the two pore sizes. A comparison was made with previously published isotherms for CO 2 on the same CPG materials. Behavior of ethane in the smaller pore size was probed further using quasi-elastic neutron scattering. By extracting the self-diffusivity and residence time, we were able to study the effect of pressure and transition from gaseous to supercritical densities on the dynamics of confined ethane. Moreover, a temperature variation QENS study was also completed with pure ethane and a CO 2–ethane mixture. Activation energies extracted from the Arrhenius plots show the effects of CO 2 addition on ethane mobility.« less

Forward Analyses of Dehydration Reactions in Mafic Rocks Along the P-T Trajectories of the Subducting Slabs

NASA Astrophysics Data System (ADS)

Kuwatani, T.; Okamoto, A.; Toriumi, M.

2005-12-01

Fluids in the subduction zone play an important role in magmatism, metamorphism, and mechanical processes involving seismic activity. Additionally, recent geophysical researches found low-frequency tremors which may be related to the movement of fluid (Obara, 2002) and a zone of high Poisson_fs ratio which reflects high pore fluid pressure (Kodaira et al.,2004) in the Southwest Japan fore-arc. It is widely accepted that these fluids are supplied by the dehydration of hydrous metamorphic minerals in the subducting oceanic plate. Although many previous studies attempted to estimate the water content of the subducting oceanic crust experimentally and theoretically (e.g., Schmidt and Poli, 1998; Hacker et al., 2003), there have been no studies which quantify the continuous dehydration reactions in detail. The aim of this study is to quantify the progress of the continuous dehydration reactions of mafic rocks in the condition of greenschist facies, corresponding to low-intermediate depth (10-50km) of warm subduction zone. We use the differential thermodynamics (Spear 1993) which include mass balance to predict the continuous metamorphic reaction history of mafic rocks along the P-T trajectory of the subducting slab. With fixed bulk chemical composition the thermodynamic system is divariant, as specified in Duhem_fs theorem. In differential thermodynamics, applying a series of changes in pressure and temperature (ΔP and ΔT, respectively) from initial conditions (P0, T0, X0s, M0s), we can trace ΔXs and ΔMs, that is, the progress (history) of the metamorphic reactions along the arbitrary P-T trajectory (Thermodynamic forward modeling). According to Okamoto and Toriumi, 2001, we modeled the greenschist/ blueschist/ (epidote -) amphibolite assemblage of mafic rocks, which consist of the following phases: Amphibole ± Epidote ± Chlorite + Plagioclase + Quartz + Fluid (H2O), in the system of Na2O - CaO - MgO - FeO - Fe2O3 - Al2O3 - SiO2 - H2O. The reference compositions and modes of minerals were assumed according to the natural sample of greenschist which has MORB-like bulk composition (Hacker et al. 2003). The reference temperature and pressure were set to be 300°C, 0.3GPa. Calculations were performed along the P-T paths of the Southwest Japan (4MPa/°C) and the Cape Mendocino (the North California, 2MPa/°C) predicted by Yamasaki and Seno, 2003. As a result, the water production rates have the peak depths at the boundary between the greenschist facies and the epidote-amphibolite facies in the Southwest Japan, and at the boundary between the greenschist facies and the amphibolite facies in the Cape Mendocino, respectively. Chlorite decomposition is the main dehydration reaction. These peak depths correspond to the zone of low frequency tremors, high Poisson_fs ratio and active seismicity (30-50km) in the Southwest Japan, and active seismicity (10-20km) in the Cape Mendocino, respectively.

Microwave plasma synthesis of Si/Ge and Si/WSi2 nanoparticles for thermoelectric applications

NASA Astrophysics Data System (ADS)

Petermann, Nils; Schneider, Tom; Stötzel, Julia; Stein, Niklas; Weise, Claudia; Wlokas, Irenäus; Schierning, Gabi; Wiggers, Hartmut

2015-08-01

The utilization of microwave-based plasma systems enables a contamination-free synthesis of highly specific nanoparticles in the gas phase. A reactor setup allowing stable, long-term operation was developed with the support of computational fluid dynamics. This paper highlights the prospects of gas-phase plasma synthesis to produce specific materials for bulk thermoelectrics. Taking advantage of specific plasma reactor properties such as Coulomb repulsion in combination with gas temperatures considerably higher than 1000 K, spherical and non-aggregated nanoparticles of multiple compositions are accessible. Different strategies towards various nanostructured composites and alloys are discussed. It is shown that, based on doped silicon/germanium alloys and composites, thermoelectric materials with zT values up to almost unity can be synthesized in one step. First experimental results concerning silicon/tungsten silicide thermoelectrics applying the nanoparticle-in-alloy idea are presented indicating that this concept might work. However, it is found that tungsten silicides show a surprising sinter activity more than 1000 K below their melting temperature.

Mineralogy and fluid content of sediments entering the Costa Rica subduction zone - Results from Site U1414, IODP Expedition 344

NASA Astrophysics Data System (ADS)

Charpentier, D.; Buatier, M.; Kutterolf, S.; Straub, S. M.; Nascimento, D.; Millan, C.

2013-12-01

Subduction zones are characterized by the largest thrust earthquakes, as quantified by both rupture area and seismic moment release. Offshore Costa Rica, the oceanic Cocos Plate subducts under the Caribbean plate forming the southern end of the Middle America trench. A high convergence rate and almost complete subduction of incoming sediments make the Costa Rica convergent margin an extremely dynamic environment. The Costa Rica Seismogenesis Project (CRISP) is designed to understand the processes that control nucleation and seismic rupture of large earthquakes at erosional subduction zones. Site U1414 of IODP Exp.344 was drilled to investigate the material from the incoming Cocos Plate. A key parameter of incoming plate is fluid content and release because it impacts deformation within the subduction complex. The deposition, compaction and diagenesis of sedimentary rocks control the distribution of fluids, fluid pressures and fluid flow patterns within subduction zones. We therefore decided to characterize sediment composition and quantify the different types of water at Site U1414. Mineralogical investigations were performed using optical and electronic microscope observations, X Ray Diffraction (on bulk and clay fractions), Cation Exchange Capacity measurements, carbon analyses (to determine carbonate contents), and sequenced extractions in NaOH (to quantify the biogenic opal content). Fluid characteristics were approached by thermal gravimetric analyses. The entire sedimentary sequence was recovered at Site U1414 and can be divided into three major sedimentary units. The first one is a hemipelagic silty clay to clay with a gradual increase of calcareous nannofossils. The dominant mineral is smectite associated in the clay fractions with kaolinite and zeolites. Small amounts of biogenic opal have been analyzed. Other minerals like quartz, feldspar and calcite are also present. The second unit is composed of nannofossil-rich calcareous ooze. The proportion of biosilica is variable and can attain 15 wt.%. Smectite and zeolites are present in smaller amount. The third unit is a lithified sandstone. Biosilica and smectite are absent, but zeolites are still present in this unit. Fluid content that can be released varies from about 15 wt.% to 40 wt.%. In shallow levels a significant proportion is pore water fluid, whereas in deeper levels water stored within minerals comprises a greater proportion of the total fluid budget. The presence of smectite yields to fluid release by dehydration and dehydroxylation at temperatures less than approximately 100°C and 500°C respectively. Transformation of biogenic opal to diagenetic silice goes to completion at temperatures of 50-100°C. It seems to be an importance source of fluid in the second unit, whereas in unit three it is zeolite water.

Efficacy of intravenous fluid warming during goal-directed fluid therapy in patients undergoing laparoscopic colorectal surgery: a randomized controlled trial.

PubMed

Choi, Ji-Won; Kim, Duk-Kyung; Lee, Seung-Won; Park, Jung-Bo; Lee, Gyu-Hong

2016-06-01

To evaluate the clinical efficacy of intravenous (IV) fluid warming in patients undergoing laparoscopic colorectal surgery. Adult patients undergoing laparoscopic colorectal surgery were randomly assigned to receive either IV fluids at room temperature (control group) or warmed IV fluids (warm fluids group). Each patient received a standardized goal-directed fluid regimen based on stroke volume variances. Oesophageal temperature was measured at 15 min intervals for 2 h after induction of anaesthesia. A total of 52 patients were enrolled in the study. The drop in core temperature in the warm fluids group was significantly less than in the control group 2 h after the induction of anaesthesia. This significant difference was seen from 30 min after induction. IV fluid warming was associated with a smaller drop in core temperature than room temperature IV fluids in laparoscopic colorectal surgery incorporating goal-directed fluid therapy. © The Author(s) 2016.

AC conductivity and dielectric behavior of bulk Furfurylidenemalononitrile

NASA Astrophysics Data System (ADS)

El-Nahass, M. M.; Ali, H. A. M.

2012-06-01

AC conductivity and dielectric behavior for bulk Furfurylidenemalononitrile have been studied over a temperature range (293-333 K) and frequency range (50-5×106 Hz). The frequency dependence of ac conductivity, σac, has been investigated by the universal power law, σac(ω)=Aωs. The variation of the frequency exponent (s) with temperature was analyzed in terms of different conduction mechanisms, and it was found that the correlated barrier hopping (CBH) model is the predominant conduction mechanism. The temperature dependence of σac(ω) showed a linear increase with the increase in temperature at different frequencies. The ac activation energy was determined at different frequencies. Dielectric data were analyzed using complex permittivity and complex electric modulus for bulk Furfurylidenemalononitrile at various temperatures.

Effect of temperature on anoxic sulfide oxidation and denitrification in the bulk wastewater phase of sewer networks.

PubMed

Mathioudakis, V L; Aivasidis, A

2009-01-01

Artificial dosage of nitrate in sewer networks is considered as one of the most effective methods for odor and corrosion control. However, there is limited knowledge on the effect of temperature on the transformations that takes place during anoxic conditions. Thus, two groups of batch experiments were conducted to gain insight in the involved processes in bulk phase of a septic municipal wastewater. It can be concluded that sewer denitrification, in bulk phase, can be simplified in three stages. According to the experimental results, nitrate or nitrite is utilized for autotrophic denitrification with sulfide, while heterotrophic utilization is initiated after the completion of anoxic sulfide oxidation. Moreover, temperature is proved to have a significant impact on sewer denitrification kinetic profile, as it determines the extent of temporal nitrite accumulation. The temperature coefficient of each anoxic process, including sulfide oxidation, nitrate utilization and denitrification/nitrite utilization is experimentally calculated and temperature dependent equations are developed, providing the rate of all anoxic processes in bulk phase of sewer wastewater, in any given temperature.

A prospective evaluation of the contribution of ambient temperatures and transport times on infrared thermometry readings of intravenous fluids utilized in EMS patients.

PubMed

Joslin, Jeremy; Fisher, Andrew; Wojcik, Susan; Cooney, Derek R

2014-01-01

During cold weather months in much of the country, the temperatures in which prehospital care is delivered creates the potential for inadvertently cool intravenous fluids to be administered to patients during their transport and care by emergency medical services (EMS). There is some potential for patient harm from unintentional infusion of cool intravenous fluids. Prehospital providers in these cold weather environments are likely using fluids that are well below room temperature when prehospital intravenous fluid (IVF) warming techniques are not being employed. It was hypothesized that cold ambient temperatures during winter months in the study location would lead to the inadvertent infusion of cold intravenous fluids during prehospital patient care. Trained student research assistants obtained three sequential temperature measurements using an infrared thermometer in a convenience sample of intravenous fluid bags connected to patients arriving via EMS during two consecutive winter seasons (2011 to 2013) at our receiving hospital in Syracuse, New York. Intravenous fluids contained in anything other than a standard polyvinyl chloride bag were not measured and were not included in the study. Outdoor temperature was collected by referencing National Weather Service online data at the time of arrival. Official transport times from the scene to the emergency department (ED) and other demographic data was collected from the EMS provider or their patient care record at the time of EMS interaction. Twenty-three intravenous fluid bag temperatures were collected and analyzed. Outdoor temperature was significantly related to the temperature of the intravenous fluid being administered, b = 0.69, t(21) = 4.3, p < 0.001. Transport time did not predict the measured intravenous fluid temperatures, b = 0.12, t(20) = 0.55, p < 0.6. Use of unwarmed intravenous fluid in the prehospital environment during times of cold ambient temperatures can lead to the infusion of cool intravenous fluid and may result in harm to patients. Short transport times do not limit this risk. Emergency departments should not rely on EMS agencies' use of intravenous fluid warming techniques and should consider replacing EMS intravenous fluids upon ED arrival to ensure patient safety.

Heat transfer and friction factor of composite TiO2-SiO2 nanofluids in water-ethylene glycol (60:40) mixture

NASA Astrophysics Data System (ADS)

Nabil, M. F.; Azmi, W. H.; Hamid, K. A.; Mamat, R.

2017-10-01

The need for high performance of heat transfer has been evaluated by finding different ways to enhance heat transfer rate in fluid. One of the methods is the combination of two or more nanoparticles and it is known as hybrid/composite nanofluids which can give better performance of heat transfer. Thus, the present study focused on combination of Titanium oxide (TiO2) and Silicon oxide (SiO2) nanoparticles dispersed in 60:40 volume ratio of water and ethylene glycol mixture as the base fluid. The TiO2-SiO2 hybrid nanofluids are prepared using two-step method for different concentration of 2.0%, 2.5% and 3.0%. The experimental determination of heat transfer coefficients are conducted in the Reynolds numbers range from 2000 to 10000 at a bulk temperature of 30°C. The experiments are undertaken for constant heat flux in a circular tube. The Nusselt number of composite TiO2- SiO2 nanofluids is observed to be higher than the base fluid. The finding on heat transfer coefficient shows that 3.0% volume concentration is the highest enhancement with 45.9% compared with base fluid. While at concentration 2.0% and 2.5%, the enhancement recorded were 29.4% and 33.2%, respectively. The friction factor of nanofluids shows a decreased with the increasing of Reynolds numbers. However, the friction factor slightly increased with the increased of concentration.

Volumetric Properties and Fluid Phase Equilibria of CO2 + H2O

DOE Office of Scientific and Technical Information (OSTI.GOV)

Capobianco, Ryan; Gruszkiewicz, Miroslaw; Wesolowski, David J

2013-01-01

The need for accurate modeling of fluid-mineral processes over wide ranges of temperature, pressure and composition highlighted considerable uncertainties of available property data and equations of state, even for the CO2 + H2O binary system. In particular, the solubility, activity, and ionic dissociation equilibrium data for the CO2-rich phase, which are essential for understanding dissolution/precipitation, fluid-matrix reactions, and solute transport, are uncertain or missing. In this paper we report the results of a new experimental study of volumetric and phase equilibrium properties of CO2 + H2O, to be followed by measurements for bulk and confined multicomponent fluid mixtures. Mixture densitiesmore » were measured by vibrating tube densimetry (VTD) over the entire composition range at T = 200 and 250 C and P = 20, 40, 60, and 80 MPa. Initial analysis of the mutual solubilities, determined from volumetric data, shows good agreement with earlier results for the aqueous phase, but finds that the data of Takenouchi and Kennedy (1964) significantly overestimated the solubility of water in supercritical CO2 (by a factor of more than two at 200 C). Resolving this well-known discrepancy will have a direct impact on the accuracy of predictive modeling of CO2 injection in geothermal reservoirs and geological carbon sequestration through improved equations of state, needed for calibration of predictive molecular-scale models and large-scale reactive transport simulations.« less

Bulk heterojunction perovskite solar cells based on room temperature deposited hole-blocking layer: Suppressed hysteresis and flexible photovoltaic application

NASA Astrophysics Data System (ADS)

Chen, Zhiliang; Yang, Guang; Zheng, Xiaolu; Lei, Hongwei; Chen, Cong; Ma, Junjie; Wang, Hao; Fang, Guojia

2017-05-01

Perovskite solar cells have developed rapidly in recent years as the third generation solar cells. In spite of the great improvement achieved, there still exist some issues such as undesired hysteresis and indispensable high temperature process. In this work, bulk heterojunction perovskite-phenyl-C61-butyric acid methyl ester solar cells have been prepared to diminish hysteresis using a facile two step spin-coating method. Furthermore, high quality tin oxide films are fabricated using pulse laser deposition technique at room temperature without any annealing procedure. The as fabricated tin oxide film is successfully applied in bulk heterojunction perovskite solar cells as a hole blocking layer. Bulk heterojunction devices based on room temperature tin oxide exhibit almost hysteresis-free characteristics with power conversion efficiency of 17.29% and 14.0% on rigid and flexible substrates, respectively.

Mechanical response and microprocesses of reconsolidating crushed salt at elevated temperature

DOE PAGES

Broome, S. T.; Bauer, S. J.; Hansen, F. D.; ...

2015-09-14

Design, analysis and performance assessment of potential salt repositories for heat-generating nuclear waste require knowledge of thermal, mechanical, and fluid transport properties of reconsolidating granular salt. So, to inform salt repository evaluations, we have undertaken an experimental program to determine Bulk and Young’s moduli and Poisson’s ratio of reconsolidated granular salt as a function of porosity and temperature and to establish the deformational processes by which the salt reconsolidates. Our tests were conducted at 100, 175, and 250 °C. In hydrostatic tests, confining pressure is increased to 20 MPa with periodic unload/reload loops to determine K. Volume strain increases withmore » increasing temperature. In shear tests at 2.5 and 5 MPa confining pressure, after confining pressure is applied, the crushed salt is subjected to a differential stress, with periodic unload/reload loops to determine E and ν. At predetermined differential stress levels the stress is held constant and the salt consolidates. Displacement gages mounted on the samples show little lateral deformation until the samples reach a porosity of ~10 %. Interestingly, vapor is vented only for 250 °C tests and condenses at the vent port. It is hypothesized that the brine originates from fluid inclusions, which were made accessible by heating and intragranular deformational processes including decrepitation. Furthermore, identification and documentation of consolidation processes are inferred from optical and scanning electron microstructural observations. As a result, densification at low porosity is enhanced by water film on grain boundaries that enables solution-precipitation phenomena.« less

Personal cooling air filtering device

DOEpatents

Klett, James [Knoxville, TN; Conway, Bret [Denver, NC

2002-08-13

A temperature modification system for modifying the temperature of fluids includes at least one thermally conductive carbon foam element, the carbon foam element having at least one flow channel for the passage of fluids. At least one temperature modification device is provided, the temperature modification device thermally connected to the carbon foam element and adapted to modify the temperature of the carbon foam to modify the temperature of fluids flowing through the flow channels. Thermoelectric and/or thermoionic elements can preferably be used as the temperature modification device. A method for the reversible temperature modification of fluids includes the steps of providing a temperature modification system including at least one thermally conductive carbon foam element having flow channels and at least one temperature modification device, and flowing a fluid through the flow channels.

Inferences from Microfractures and Geochemistry in Dynamic Shale-CO2 Packed Bed Experiments

NASA Astrophysics Data System (ADS)

Radonjic, M.; Olabode, A.

2016-12-01

Subsurface storage of large volumes of carbondioxide (CO2) is expected to have long term rock-fluid interactions impact on reservoir and seal rocks properties. Caprocks, particularly sedimentary types, are the ultimate hydraulic barrier in carbon sequestration. The mineralogical components of sedimentary rocks are geochemically active under enormous earth stresses, which generate high pressure and temperature conditions. It has been postulated that in-situ mineralization can lead to flow impedance in natural fractures in the presence of favorable geochemical and thermodynamic conditions. This experimental modelling research investigated the impact of in-situ geochemical precipitation on conductivity of fractures. Geochemical analyses were performed on four different samples of shale rocks, effluent fluids and recovered precipitates both before and after CO2-brine flooding of crushed shale rocks at moderately high temperature and pressure conditions. The results showed that most significant diagenetic changes in shale rocks after flooding with CO2-brine, reflected in the effluent fluid with predominantly calcium based minerals dissolving and precipitating under experimental conditions. Major and trace elements in the effluent (using ICP-OES analysis) indicated that multiple geochemical reactions are occurring with almost all of the constituent minerals participating. The geochemical composition of precipitates recovered after the experiments showed diagenetic carbonates and opal as the main constituents. The bulk rock showed little changes in composition except for sharper and more refined peaks on XRD analysis, suggesting that a significant portion of the amorphous content of the rocks have been removed via dissolution by the slightly acid CO2-brine fluid that was injected. Micro-indentation results captured slight reduction in the hardness of the shale rocks and this reduction appeared dependent on diagenetic quartz content. It can be inferred that convective reactive transport of dissolved minerals are involved in nanoscale precipitation-dissolution processes in shale. This reactive transport of dissolved minerals can occlude micro-fracture flow paths, thereby improving shale caprock seal integrity with respect to leakage risk under CO2 sequestration conditions.

Field and Laboratory Observations on Fluid Budget of the Cascadia Episodic Tremor and Slip System, Olympic Peninsula, Washington

NASA Astrophysics Data System (ADS)

Rotman, H.; Mattinson, C. G.

2009-12-01

Fluid movement in accretionary prisms has been linked to the recently discovered episodic tremor and slip (ETS) events along subduction zones. This study focuses on the exhumed accretionary prism of the Cascadia subduction zone, where ETS events are well-documented. The exposed sandstone, shale, siltstone and minor basalt in the study location were buried to 6 - 15 km, within the depth constraints of ETS. This past summer, field work focused on observations of subduction related fluid budget as evidenced by veins, metamorphism, and pore space took place along an east-west transect of the Olympic Peninsula. Approximately 40 representative samples were collected near Obstruction Peak, Hurricane Ridge, Lake Mills (Elwha), and Sore Thumb (Sol Duc). Observations indicate progressively increasing grade of metamorphism from west to east, in agreement with previous studies. Mudrocks show a clear progression from shale to phyllite, while sandstones generally appear equally micaceous across the transect, with the exception of one location. This location is unique in that micas are larger, other metamorphic indicators are visible in hand specimen, and veins make up a significant percent of the outcrop. Epidotes are visible in the rock body and veins, and the veins also contain quartz and calcite, usually as the primary mineral. Veins are oriented perpendicular to bedding and are primarily found in the coarser units. In addition to the veins, water is present in pore spaces and mineral structure. Preliminary observations indicate the veins and pore space decrease to the east, while evidence for fluid movement increases to the east. These observations will be tested and quantified by a variety of laboratory analyses. Thin section examination will determine pore space and mineral assemblages at different locations, and the mechanisms (e.g., blocky or fibrous) of vein growth. Element concentrations from whole rock analysis will determine bulk composition and element mobilization at different temperatures. Oxygen ratios from quartz and calcite, and titanium activity, will constrain temperatures.

Volume-energy parameters for heat transfer to supercritical fluids

NASA Technical Reports Server (NTRS)

Kumakawa, A.; Niino, M.; Hendricks, R. C.; Giarratano, P. J.; Arp, V. D.

1986-01-01

Reduced Nusselt numbers of supercritical fluids from different sources were grouped by several volume-energy parameters. A modified bulk expansion parameter was introduced based on a comparative analysis of data scatter. Heat transfer experiments on liquefied methane were conducted under near-critical conditions in order to confirm the usefulness of the parameters. It was experimentally revealed that heat transfer characteristics of near-critical methane are similar to those of hydrogen. It was shown that the modified bulk expansion parameter and the Gibbs-energy parameter grouped the heat transfer data of hydrogen, oxygen and methane including the present data on near-critical methane. It was also indicated that the effects of surface roughness on heat transfer were very important in grouping the data of high Reynolds numbers.

Chain Stretching and Order-Disorder Transitions in Block Copolymer Monolayers and Multilayers

NASA Astrophysics Data System (ADS)

Kramer, Edward J.; Mishra, Vindhya; Stein, Gila E.; Sohn, Karen E.; Hur, Sumi; Fredrickson, Glenn H.; Cochran, Eric W.

2009-03-01

Both monolayers of block copolymer cylinders and spheres undergo order to disorder transitions (ODT) at temperatures well below those of the bulk. Monolayers of PS-b-P2VP cylinders undergo a ``nematic'' to ``isotropic'' transition at temperatures about 20 K below the bulk ODT while monolayers of PS-b-P2VP with P2VP spheres undergo a 2D crystal to hexatic transition at least 10 K below the bulk ODT. Bilayers of each structure disorder at temperatures well above that of the monolayers. While one is tempted to attribute all of the difference to the fact that ordered monolayers are quasi 2 dimensional while bilayers are not, an alternative explanation exists. In the cylinder monolayer the corona PS chains must stretch to fill a nearly square cross-section domain rather than a hexagonal one in the bulk, while the corona PS chains in a sphere monolayer must stretch to fill a hexagonal prism rather than an octahedron in the bulk. The more non-uniform stretching of the chains in the monolayer should increase its free energy and decrease its order-disorder temperature.

Direct laboratory observation of fluid distribution and its influence on acoustic properties of patchy saturated rocks

NASA Astrophysics Data System (ADS)

Lebedev, M.; Clennell, B.; Pervukhina, M.; Shulakova, V.; Mueller, T.; Gurevich, B.

2009-04-01

Porous rocks in hydrocarbon reservoirs are often saturated with a mixture of two or more fluids. Interpretation of exploration seismograms requires understanding of the relationship between distribution of the fluids patches and acoustic properties of rocks. The sizes of patches as well as their distribution affect significantly the seismic response. If the size of the fluid patch is smaller than the diffusion wavelength then pressure equilibration is achieved and the bulk modulus of the rock saturated with a mixture is defined by the Gassmann equations (Gassmann, 1951) with the saturation-weighted average of the fluid bulk modulus given by Wood's law (Wood, 1955, Mavko et al., 1998). If the fluid patch size is much larger than the diffusion wavelength then there is no pressure communication between different patches. In this case, fluid-flow effects can be neglected and the overall rock may be considered equivalent to an elastic composite material consisting of homogeneous parts whose properties are given by Gassmann theory with Hill's equation for the bulk modulus (Hill, 1963, Mavko et al., 1998). At intermediate values of fluid saturation the velocity-saturation relationship is significantly affected by the fluid patch distribution. In order to get an improved understanding of factors influencing the patch distribution and the resulting seismic wave response we performed simultaneous measurements of P-wave velocities and rock sample CT imaging. The CT imaging allows us to map the fluid distribution inside rock sample during saturation (water imbibition). We compare the experimental results with theoretical predictions. In this paper we will present results of simultaneous measurements of longitudinal wave velocities and imaging mapping of fluid distribution inside rock sample during sample saturation. We will report results of two kinds of experiments: "dynamic" and "quasi static" saturation. In both experiments Casino Cores Otway Basin sandstone, Australia core samples (38 mm in diameter, approximately 60 mm long) were dried in oven under reduced pressure. In dynamic saturation experiments, samples were jacketed in the experimental cell, made from transparent for X-radiation material (PMMA). Distillate water was injected into the sample from the one side. Fluid distribution in such "dynamic" experiment: both spatial and time dependant was measured using X-ray Computer Tomograph (CT) with resolution 0.2 x 0.2 x 1 mm3. Velocities (Vp, and Vs) at ultrasonic frequency of 1 MHz, were measured in the direction perpendicular to initial direction of the fluid flow injection. Sample saturation was estimated from the CT results. In "quasi static" experiments samples were saturated during long period of time (over 2 weeks) to achieve uniform distribution of liquid inside the sample. Saturation was determined by measurement of the weight of water fraction. All experiments were performed at laboratory environments at temperature 25 C. Ultrasonic velocities and fluid saturations were measured simultaneously during water injection into sandstone core samples. The experimental results obtained on low-permeability samples show that at low saturation values the velocity-saturation dependence can be described by the Gassmann-Wood relationship. However, with increasing saturation a sharp increase of P-wave velocity is observed, eventually approaching the Gassmann-Hill relationship. We connect the characteristics of the transition behavior of the velocity-saturation relationships to the increasing size of the patches inside the rock sample. In particular, we show that for relatively large fluid injection rate this transition occurs at smaller degrees of saturation as compared with high injection rate. We model the experimental data using the so-called White model (Toms 2007) that assumes fluid patch distribution as a periodic assemblage of concentric spheres. We can observe reasonable agreement between experimental results and theoretical predictions of White's model. The results illustrate the non-unique relationships between saturation and velocity in sandstones dependent on texture and fluid displacement history: fuller understanding of these phenomena is needed for accurate assessment of time lapse seismic measurements, be they for oil and gas recovery or for CO2 disposal purposes. Gassmann, F., 1951, Elastic waves through a packing of spheres. Geophysics 16, 673-685; Mavko, G., T. Mukerji, and J. Dvorkin, 1998, The Rock Physics Handbook: Tools for seismic analysis in porous media: Cambridge University Press. Wood, A. W., 1955, A Textbook of Sound, The MacMillan Co., New York, 360 pp. Hill, R., 1963, Elastic properties of reinforced solids: some theoretical principles. J. Mech. Phys. Solids, 11, 357-372. Hill, R., 1952, The elastic behavior of crystalline aggregates. Proc. Physical Soc., London, A65, 349-354. J. Toms, T.M. Mueller, B. Gurevich, 2007 Seismic attenuation in porous rocks with random patchy saturation. Geophysical Prospecting, 55, 671-678.

Lithium elemental and isotopic disequilibrium in minerals from peridotite xenoliths from far- east Russia: product of recent melt/fluid-rock reaction

NASA Astrophysics Data System (ADS)

Rudnick, R. L.; Ionov, D. A.

2006-12-01

Peridotite xenoliths from the Tok and Barhatny localities in far-east Russia are characterized by strong Li elemental and isotopic disequilibria caused by addition of Li to the rocks via diffusion from a small-volume grain boundary fluid or melt. Because Li diffuses rapidly at mantle temperatures, the disequilibrium is a transient feature and its preservation in these samples indicates that Li addition occurred shortly before or even during the entrainment of the xenoliths in the host basalts. δ&^{7}Licpx is consistently lower than that of coexisting olivines and Δ&^{7}Liol-cpx, which ranges from 2.8 to 22.9‰,correlates with bulk rock composition. The most refractory samples experienced the greatest overall Li addition and most closely approximate elemental and isotopic equilibrium due to longer equilibration times and probably also greater infiltration of the Li-bearing melt or fluid. The variable but often extreme isotopic compositions produced by this process (δ&^{7}Licpx down to -15 and δ&^{7}Liol up to +12) do not reflect the presence of an isotopically exotic recycled component, as has been previously inferred for xenoliths from this region. The best estimate for the δ&^{7}Li of the source of the Li in the Tok xenoliths is δ&^{7}Li = +1.4, which is identical to that of the host basalt. A single sample from the Koppy locality, which is situated closest to the paleo-Pacific subduction zone, shows both elemental and isotopic equilibration of Li and has a "normal" δ&^{7}Licpx of +3.5. The analytically identical δ&^{7}Li of olivine and cpx from this sample, coupled with its relatively low equilibration temperature of 990°C suggests that there is no discernible Li isotopic fractionation between coexisting minerals at mantle temperatures. This study highlights the very large isotopic effects that can be produced via kinetic fractionation in peridotite xenoliths at high temperatures and associated with host-rock xenolith interactions.

Ultrasonic Seismic Wave Elastic Moduli and Attenuation, Petro physical Models and Work Flows for Better Subsurface Imaging Related to Monitoring of Sequestrated Supercritical CO2 and Geothermal Energy Exploration

NASA Astrophysics Data System (ADS)

Harbert, W.; Delaney, D.; Mur, A. J.; Purcell, C.; Zorn, E.; Soong, Y.; Crandall, D.; Haljasmaa, I.

2016-12-01

To better understand the petrophysical response at ultrasonic frequencies in rhyolite and carbonate (relevant to CO2 storage and CO2 enhanced oil recovery) lithologies we conducted core analysis incorporating variation in temperature, effective pressure and pore filling fluid. Ultrasonic compressive and shear wave (VP, VS1 and VS2) velocities were measured allowing calculation of the Bulk modulus (K), Young's modulus (E), Lamè's first parameter (λ), Shear modulus (G), Poisson's ratio (ν), and P-wave modulus (M). In addition, from the ultrasonic waveform data collected, we employed the spectral ratio method to estimate the quality factor. Carbonate samples were tested dry, using atmospheric gas as the pore phase, and with deionized water, oil, and supercritical CO2. We observed that Qp was directly proportional to effective pressure in our rhyolite samples. In addition, we observed effects of core anisotropy on Qp, however this was not apparent in higher porosity samples. Increasing effective pressure seems to decrease the effects of ultrasonic P-wave anisotropy. Qp was inversely proportional to temperature, however this was not observed for higher porosity samples. Qp was highly dependent on the rock porosity. Higher porosity samples displayed significantly lower values of Qp. In our experiments we observed that ultrasonic wave scattering due to heterogeneities in the carbonate samples was dominant. Although we observed lower μρ values, trends in our data strongly agreed with the model proposed workers interpreting AVO trends in a LMR cross plot space. We found that μρ was proportional to temperature while λρ was temperature independent and that λρ-μρ trends were extremely dependent on porosity. Higher porosity results in lower values for both λρ and μρ. The presence of fluids causes a distinct shift in λρ values, an observation which could provide insight into subsurface exploration using amplitude variation with offset (AVO) classification. We present approaches to incorporate these laboratory results into well log calibrated MATLAB based Gassmann-Biot fluid substitution models incorporating compliant porosity, Thomsen parameters models that utilize orthorhombic velocity anisotropy to predict seismic responses.

Apparatus for characterizing the temporo-spatial properties of a dynamic fluid front and method thereof

DOEpatents

Battiste, Richard L.

2007-12-25

Methods and apparatus are described for characterizing the temporal-spatial properties of a dynamic fluid front within a mold space while the mold space is being filled with fluid. A method includes providing a mold defining a mold space and having one or more openings into the mold space; heating a plurality of temperature sensors that extend into the mold space; injecting a fluid into the mold space through the openings, the fluid experiencing a dynamic fluid front while filling the mold space with the fluid; and characterizing temporal-spatial properties of the dynamic fluid front by monitoring a temperature of each of the plurality of heated temperature sensors while the mold space is being filled with the fluid. An apparatus includes a mold defining a mold space; one or more openings for introducing a fluid into the mold space and filling the mold space with the fluid, the fluid experiencing a dynamic fluid front while filling the mold space; a plurality of heated temperature sensors extending into the mold space; and a computer coupled to the plurality of heated temperature sensors for characterizing the temporal-spatial properties of the dynamic fluid front.

Factors influencing leaching of PBDEs from waste cathode ray tube plastic housings.

PubMed

Stubbings, William A; Harrad, Stuart

2016-11-01

Samples of waste cathode ray tube (CRT) plastic housings were exposed to Milli-Q® water containing dissolved humic matter at concentrations of 0, 100 and 1000mgL(-1) as leaching fluid under laboratory conditions, and polybrominated diphenyl ethers (PBDEs) determined in the resulting leachate. Despite the relatively hydrophobic physicochemical properties of PBDEs, concentrations of ƩPBDEs in the leachate from the leaching experiments in this study ranged from 14,000 to 200,000ngL(-1). PBDE leaching appears to be a second order process, whereby a period of initially intense dissolution of more labile PBDEs is followed by a slower stage corresponding to external diffusion of the soluble residue in the material. The bulk of transfer of PBDEs to the leaching fluid occurs within the first 6h of contact, during which time we suggest that the most labile PBDEs are "washed" off the surface of the CRT plastics. The predominant congeners in the chips were BDE-209 (2600mgkg(-1)) and BDE 183 (220mgkg(-1)). The impacts on PBDE leaching of leachate pH and temperature were also examined. Increasing the temperature of leaching fluids from 20 to 80°C, enhances the leachability of BDE-209 and BDE-99 from plastics. In all cases, the alkaline pH8.5 examined, resulted in the greatest PBDE concentrations in leachate. Agitation of the waste/leachate mixture enhances PBDE leaching from CRT plastics. Potential evidence for debromination of heavy congeners to the lower brominated and more bioavailable BDEs was observed. Specifically, BDEs-47, -85 and -100 were detected in the leachates, but were absent from the CRT plastics themselves. Copyright © 2016. Published by Elsevier B.V.

Microvolume index of refraction determinations by interferometric backscatter

NASA Astrophysics Data System (ADS)

Bornhop, Darryl J.

1995-06-01

A new method has been applied to the determination of fluid bulk properties in small detection volumes. Through the use of an unfocused He-Ne laser beam and a cylindrical tube of capillary dimensions, relative refractive-index measurements are possible. The backscattered light from the illumination of a tube of capillary dimensions produces an interference pattern that is spatially defined and that contains information related to the bulk properties of the fluid contained in the tube. Positional changes in the intensity-modulated beam profile (interference fringes) are directly related to the refractive index of the fluid in the tube. The determination of dn/n at the 10-7 level is possible in probe volumes of 350 pL. The technique has been applied to tubes as small as 75 mu m inner diameter and as large as 1.0 mm inner diameter. No modification of the simple optical bench is required for facilitating the determination of refractive index for the complete range of tube diameters.

High bulk modulus of ionic liquid and effects on performance of hydraulic system.

PubMed

Kambic, Milan; Kalb, Roland; Tasner, Tadej; Lovrec, Darko

2014-01-01

Over recent years ionic liquids have gained in importance, causing a growing number of scientists and engineers to investigate possible applications for these liquids because of their unique physical and chemical properties. Their outstanding advantages such as nonflammable liquid within a broad liquid range, high thermal, mechanical, and chemical stabilities, low solubility for gases, attractive tribological properties (lubrication), and very low compressibility, and so forth, make them more interesting for applications in mechanical engineering, offering great potential for new innovative processes, and also as a novel hydraulic fluid. This paper focuses on the outstanding compressibility properties of ionic liquid EMIM-EtSO4, a very important physical chemically property when IL is used as a hydraulic fluid. This very low compressibility (respectively, very high Bulk modulus), compared to the classical hydraulic mineral oils or the non-flammable HFDU type of hydraulic fluids, opens up new possibilities regarding its usage within hydraulic systems with increased dynamics, respectively, systems' dynamic responses.

Local shear stress and its correlation with local volume fraction in concentrated non-Brownian suspensions: Lattice Boltzmann simulation

NASA Astrophysics Data System (ADS)

Lee, Young Ki; Ahn, Kyung Hyun; Lee, Seung Jong

2014-12-01

The local shear stress of non-Brownian suspensions was investigated using the lattice Boltzmann method coupled with the smoothed profile method. Previous studies have only focused on the bulk rheology of complex fluids because the local rheology of complex fluids was not accessible due to technical limitations. In this study, the local shear stress of two-dimensional solid particle suspensions in Couette flow was investigated with the method of planes to correlate non-Newtonian fluid behavior with the structural evolution of concentrated particle suspensions. Shear thickening was successfully captured for highly concentrated suspensions at high particle Reynolds number, and both the local rheology and local structure of the suspensions were analyzed. It was also found that the linear correlation between the local particle stress and local particle volume fraction was dramatically reduced during shear thickening. These results clearly show how the change in local structure of suspensions influences the local and bulk rheology of the suspensions.

Cerebrospinal fluid bulk flow is driven by the cardiac cycle

NASA Astrophysics Data System (ADS)

Tithof, Jeffrey; Mestre, Humberto; Thomas, John; Nedergaard, Maiken; Kelley, Douglas

2017-11-01

Recent discoveries have uncovered a cerebrospinal fluid (CSF) transport system in the perivascular spaces (PVS) of the mammalian brain which clears excess extracellular fluid and protein waste products. The oscillatory pattern of CSF flow has long been attributed to arterial pulsations due to cardiac contractility but limitations in imaging techniques have impeded quantitative measurement of flow rates within the PVS. In this talk, we describe quantitative measurements from the first ever direct imaging of CSF flow in the PVS of a mouse brain. We perform particle tracking velocimetry to obtain time-resolved velocity measurements. To identify the cardiac and/or respiratory dependence of the flow, while imaging, we simultaneously record the mouse's electrocardiogram and respiration. Our measurements conclusively indicate that CSF pulsatility in the arterial PVS is directly driven by the cardiac cycle and not by the respiratory cycle or cerebral vasomotion. These results offer a substantial step forward in understanding bulk flow of CSF in the mammalian brain and may have important implications related to neurodegenerative diseases.

Bulk viscosity and relaxation time of causal dissipative relativistic fluid dynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang Xuguang; Rischke, Dirk H.; Institut fuer Theoretische Physik, J.W. Goethe-Universitaet, D-60438 Frankfurt am Main

2011-02-15

The microscopic formulas of the bulk viscosity {zeta} and the corresponding relaxation time {tau}{sub {Pi}} in causal dissipative relativistic fluid dynamics are derived by using the projection operator method. In applying these formulas to the pionic fluid, we find that the renormalizable energy-momentum tensor should be employed to obtain consistent results. In the leading-order approximation in the chiral perturbation theory, the relaxation time is enhanced near the QCD phase transition, and {tau}{sub {Pi}} and {zeta} are related as {tau}{sub {Pi}={zeta}}/[{beta}{l_brace}(1/3-c{sub s}{sup 2})({epsilon}+P)-2({epsilon}-3P)/9{r_brace}], where {epsilon}, P, and c{sub s} are the energy density, pressure, and velocity of sound, respectively. The predictedmore » {zeta} and {tau}{sub {Pi}} should satisfy the so-called causality condition. We compare our result with the results of the kinetic calculation by Israel and Stewart and the string theory, and confirm that all three approaches are consistent with the causality condition.« less

Marangoni convection in molten salts

NASA Astrophysics Data System (ADS)

Cramer, A.; Landgraf, S.; Beyer, E.; Gerbeth, G.

2011-02-01

Marangoni convection is involved in many technological processes. The substances of industrial interest are often governed by diffusive heat transport and their physical modelling is limited with respect to the Prandtl number Pr. The present paper addresses this deficiency. Studies were made on molten salts having Pr values in an intermediate range well below that of the typically employed organics. Since some of the selected species have a relatively high melting point, a high-temperature facility which allows studying thermocapillary convection at temperatures in excess of 1,000°C was built. The results presented here were obtained in a cylindrical geometry, although the equipment that was built is not restricted to this configuration because of its modular construction. Modelled after some applications, the fluid was heated centrically on top. The bulk was embedded in a large thermostatically controlled reservoir so as to establish the lower ambient reference temperature. A characteristic size of the experimental cell was chosen such that, on the one hand, the dynamic Bond number Bo did not become too high; on the other hand, the liquid had to have a certain depth to allow particle image velocimetry. The complicated balance between body forces and thermocapillary forces in the case of intermediate Bo was found to result in a distinct local separation into a bulk motion governed by natural convection with a recirculating Marangoni flow on top. In contrast to low viscosity organics, the vapour pressure of which increases considerably with decreasing Pr, high values of the Marangoni number can be reached. Comparisons of the topology of Marangoni vortices between molten salts with 2.3 ⩽ Pr ⩽ 6.4 and a silicone oil with Pr typically one order of magnitude higher suggest that the regime of non-negligible heat diffusion is entered.

Partial melting of TTG gneisses: crustal contamination and the production of granitic melts

NASA Astrophysics Data System (ADS)

Meade, F. C.; Masotta, M.; Troll, V. R.; Freda, C.; Johnson, T. E.; Dahren, B.

2011-12-01

Understanding partial melting of ancient TTG gneiss terranes is crucial when considering crustal contamination in volcanic systems, as these rocks are unlikely to melt completely at magmatic temperatures (1000-1200 °C) and crustal pressures (<500 MPa). Variations in the bulk composition of the gneiss, magma temperature, pressure (depth) and the composition and abundance of any fluids present will produce a variety of melt compositions, from partial melts enriched in incompatible elements to more complete melts, nearing the bulk chemistry of the parent gneiss. We have used piston cylinder experiments to simulate partial melting in a suite of 12 gneisses from NW Scotland (Lewisian) and Eastern Greenland (Ammassalik, Liverpool Land) under magma chamber temperature and pressure conditions (P=200 MPa, T=975 °C). These gneisses form the basement to much of the North Atlantic Igneous Province, where crustal contamination of magmas was commonplace but the composition of the crustal partial melts are poorly constrained [1]. The experiments produced partial melts in all samples (e.g. Fig 1). Electron microprobe analyses of glasses indicate they are compositionally heterogeneous and are significantly different from the whole rock chemistry of the parent gneisses. The melts have variably evolved compositions but are typically trachy-dacitic to rhyolitic (granitic). This integrated petrological, experimental and in-situ geochemical approach allows quantification of the processes of partial melting of TTG gneiss in a volcanic context, providing accurate major/trace element and isotopic (Sr, Pb) end-members for modeling crustal contamination. The experimental melts and restites will be compared geochemically with a suite of natural TTG gneisses, providing constraints on the extent to which the gneisses have produced and subsequently lost melt. [1] Geldmacher et al. (2002) Scottish Journal of Geology, v.38, p.55-61.

Anatomy and pathophysiology of the pleura and pleural space.

PubMed

Yalcin, Nilay Gamze; Choong, Cliff K C; Eizenberg, Norman

2013-02-01

Pleural effusions are most often secondary to an underlying condition and may be the first sign of the underlying pathologic condition. The balance between the hydrostatic and oncotic forces dictates pleural fluid homeostasis. The parietal pleura has a more significant role in pleural fluid homeostasis. Its vessels are closer to the pleural space compared with its visceral counterpart; it contains lymphatic stomata, absent on visceral pleura, which are responsible for a bulk clearance of fluid. The diagnosis and successful treatment of pleural effusions requires a mixture of imaging techniques and pleural fluid analysis. Copyright © 2013. Published by Elsevier Inc.

How animals drink and swim in fluids

NASA Astrophysics Data System (ADS)

Jung, Sunghwan

2011-10-01

Fluids are essential for most living organisms to maintain a healthy body and also serve as a medium in which they locomote. The fluid bulk or interfaces actively interact with biological structures, which produces highly nonlinear, interesting, and complicated dynamical problems. We studied the lapping of cats and the swimming of Paramecia in various fluidic environments. The problem of the cat drinking can be simplified as the competition between inertia and gravity whereas the problem of Paramecium swimming in viscous fluids results from the competition between viscous drag and thrust. The underlying mechanisms are discussed and understood through laboratory experiments utilizing high-speed photography.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mallow, Anne M; Abdelaziz, Omar; Graham, Samuel

The thermal charging performance of phase change materials, specifically paraffin wax, combined with compressed expanded natural graphite foam is studied under constant heat flux and constant temperature conditions. By varying the heat flux between 0.39 W/cm2 and 1.55 W/cm2 or maintaining a boundary temperature of 60 C for four graphite foam bulk densities, the impact on the rate of thermal energy storage is discussed. Thermal charging experiments indicate that thermal conductivity of the composite is an insufficient metric to compare the influence of graphite foam on the rate of thermal energy storage of the PCM composite. By dividing the latentmore » heat of the composite by the time to melt for various boundary conditions and graphite foam bulk densities, it is determined that bulk density selection is dependent on the applied boundary condition. A greater bulk density is advantageous for samples exposed to a constant temperature near the melting temperature as compared to constant heat flux conditions where a lower bulk density is adequate. Furthermore, the anisotropic nature of graphite foam bulk densities greater than 50 kg/m3 is shown to have an insignificant impact on the rate of thermal charging. These experimental results are used to validate a computational model for future use in the design of thermal batteries for waste heat recovery.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tierno, S. P., E-mail: sp.tierno@upm.es; Donoso, J. M.; Domenech-Garret, J. L.

The interaction between an electron emissive wall, electrically biased in a plasma, is revisited through a simple fluid model. We search for realistic conditions of the existence of a non-monotonic plasma potential profile with a virtual cathode as it is observed in several experiments. We mainly focus our attention on thermionic emission related to the operation of emissive probes for plasma diagnostics, although most conclusions also apply to other electron emission processes. An extended Bohm criterion is derived involving the ratio between the two different electron densities at the potential minimum and at the background plasma. The model allows amore » phase-diagram analysis, which confirms the existence of the non-monotonic potential profiles with a virtual cathode. This analysis shows that the formation of the potential well critically depends on the emitted electron current and on the velocity at the sheath edge of cold ions flowing from the bulk plasma. As a consequence, a threshold value of the governing parameter is required, in accordance to the physical nature of the electron emission process. The latter is a threshold wall temperature in the case of thermionic electrons. Experimental evidence supports our numerical calculations of this threshold temperature. Besides this, the potential well becomes deeper with increasing electron emission, retaining a fraction of the released current which limits the extent of the bulk plasma perturbation. This noninvasive property would explain the reliable measurements of plasma potential by using the floating potential method of emissive probes operating in the so-called strong emission regime.« less

Warm layer and cool skin corrections for bulk water temperature measurements for air-sea interaction studies

NASA Astrophysics Data System (ADS)

Alappattu, Denny P.; Wang, Qing; Yamaguchi, Ryan; Lind, Richard J.; Reynolds, Mike; Christman, Adam J.

2017-08-01

The sea surface temperature (SST) relevant to air-sea interaction studies is the temperature immediately adjacent to the air, referred to as skin SST. Generally, SST measurements from ships and buoys are taken at depths varies from several centimeters to 5 m below the surface. These measurements, known as bulk SST, can differ from skin SST up to O(1°C). Shipboard bulk and skin SST measurements were made during the Coupled Air-Sea Processes and Electromagnetic ducting Research east coast field campaign (CASPER-East). An Infrared SST Autonomous Radiometer (ISAR) recorded skin SST, while R/V Sharp's Surface Mapping System (SMS) provided bulk SST from 1 m water depth. Since the ISAR is sensitive to sea spray and rain, missing skin SST data occurred in these conditions. However, SMS measurement is less affected by adverse weather and provided continuous bulk SST measurements. It is desirable to correct the bulk SST to obtain a good representation of the skin SST, which is the objective of this research. Bulk-skin SST difference has been examined with respect to meteorological factors associated with cool skin and diurnal warm layers. Strong influences of wind speed, diurnal effects, and net longwave radiation flux on temperature difference are noticed. A three-step scheme is established to correct for wind effect, diurnal variability, and then for dependency on net longwave radiation flux. Scheme is tested and compared to existing correction schemes. This method is able to effectively compensate for multiple factors acting to modify bulk SST measurements over the range of conditions experienced during CASPER-East.

Influence of precipitating light elements on stable stratification below the core/mantle boundary

NASA Astrophysics Data System (ADS)

O'Rourke, J. G.; Stevenson, D. J.

2017-12-01

Stable stratification below the core/mantle boundary is often invoked to explain anomalously low seismic velocities in this region. Diffusion of light elements like oxygen or, more slowly, silicon could create a stabilizing chemical gradient in the outermost core. Heat flow less than that conducted along the adiabatic gradient may also produce thermal stratification. However, reconciling either origin with the apparent longevity (>3.45 billion years) of Earth's magnetic field remains difficult. Sub-isentropic heat flow would not drive a dynamo by thermal convection before the nucleation of the inner core, which likely occurred less than one billion years ago and did not instantly change the heat flow. Moreover, an oxygen-enriched layer below the core/mantle boundary—the source of thermal buoyancy—could establish double-diffusive convection where motion in the bulk fluid is suppressed below a slowly advancing interface. Here we present new models that explain both stable stratification and a long-lived dynamo by considering ongoing precipitation of magnesium oxide and/or silicon dioxide from the core. Lithophile elements may partition into iron alloys under extreme pressure and temperature during Earth's formation, especially after giant impacts. Modest core/mantle heat flow then drives compositional convection—regardless of thermal conductivity—since their solubility is strongly temperature-dependent. Our models begin with bulk abundances for the mantle and core determined by the redox conditions during accretion. We then track equilibration between the core and a primordial basal magma ocean followed by downward diffusion of light elements. Precipitation begins at a depth that is most sensitive to temperature and oxygen abundance and then creates feedbacks with the radial thermal and chemical profiles. Successful models feature a stable layer with low seismic velocity (which mandates multi-component evolution since a single light element typically increases seismic velocity) growing to its present-day size while allowing enough precipitation to drive compositional convection below. Crucially, this modeling offers unique constrains on Earth's accretion and the light element composition of the core compared to degenerate estimates derived from bulk density and seismic measurements.

Zero-Boil-Off Tank (ZBOT) Experiment: Ground-Based Validation of Self-Pressurization and Pressure Control Two-Phase CFD Model

NASA Technical Reports Server (NTRS)

Kassemi, Mohammad; Hylton, Sonya; Kartuzova, Olga

2017-01-01

Integral to all phases of NASA's projected space and planetary expeditions is affordable and reliable cryogenic fluid storage for use in propellant or life support systems. Cryogen vaporization due to heat leaks into the tank from its surroundings and support structure can cause self-pressurization relieved through venting. This has led to a desire to develop innovative pressure control designs based on mixing of the bulk tank fluid together with some form of active or passive cooling to allow storage of the cryogenic fluid with zero or reduced boil-off. The Zero-Boil-Off Tank (ZBOT) Experiments are a series of small scale tank pressurization and pressure control experiments aboard the International Space Station (ISS) that use a transparent volatile simulant fluid in a transparent sealed tank to delineate various fundamental fluid flow, heat and mass transport, and phase change phenomena that control storage tank pressurization and pressure control in microgravity. The hardware for ZBOT-1 flew to ISS on the OA-7 flight in April 2017 and operations are planned to begin in September 2017, encompassing more than 90 tests. This paper presents preliminary results from ZBOT's ground-based research delineating both pressurization and pressure reduction trends in the sealed test tank. Tank self-pressurization tests are conducted under three modes: VJ heating, strip heating and simultaneous VJ and strip heating in attempt to simulate heat leaks from the environment, the support structure and both. The jet mixing pressure control studies are performed either from an elevated uniform temperature condition or from thermally stratified conditions following a self-pressurization run. Jet flow rates are varied from 2-25 cm/s spanning a range of jet Re number in laminar, transitional, and turbulent regimes and a range of Weber numbers covering no ullage penetration, partial penetration and complete ullage penetration and break-up (only in microgravity). Numerical prediction of a two-phase CFD model are compared to experimental 1g results to both validate the model and also indicate the effect of the residual non-condensable gas on evolution of pressure and temperature distributions in the tank during pressurization and pressure control.

A systematic review of randomised controlled trials of the effects of warmed irrigation fluid on core body temperature during endoscopic surgeries.

PubMed

Jin, Yinghui; Tian, Jinhui; Sun, Mei; Yang, Kehu

2011-02-01

The purpose of this systematic review was to establish whether warmed irrigation fluid temperature could decrease the drop of body temperature and incidence of shivering and hypothermia. Irrigation fluid, which is used in large quantities during endoscopic surgeries at room temperature, is considered to be associated with hypothermia and shivering. It remains controversial whether using warmed irrigation fluid to replace room-temperature irrigation fluid will decrease the drop of core body temperature and the occurrence of hypothermia. A comprehensive search (computerised database searches, footnote chasing, citation chasing) was undertaken to identify all the randomised controlled trials that explored temperature of irrigation fluid in endoscopic surgery. An approach involving meta-analysis was used. We searched PubMed, EMBASE, Cochrane Library, SCI, China academic journals full-text databases, Chinese Biomedical Literature Database, Chinese scientific journals databases and Chinese Medical Association Journals for trials that meet the inclusion criteria. Study quality was assessed using standards recommended by Cochrane Library Handbook 5.0.1. Disagreement was resolved by consensus. Thirteen randomised controlled trials including 686 patients were identified. The results showed that room-temperature irrigation fluid caused a greater drop of core body temperature in patients, compared to warmed irrigation fluid (p < 0.00001; I(2) = 85%). The occurrence of shivering [odds ratio (OR) 5.13, 95% CI: 2.95-10.19, p < 0.00001; I(2) = 0%] and hypothermia (OR 22.01, 95% CI: 2.03-197.08, p = 0.01; I(2) = 64%) in the groups having warmed irrigation fluid were lower than the group of studies having room-temperature fluid. In endoscopic surgeries, irrigation fluid is recommended to be warmed to decrease the drop of core body temperature and the risk of perioperative shivering and hypothermia. Warming irrigating fluid should be considered standard practice in all endoscopic surgeries. © 2011 Blackwell Publishing Ltd.

Performance of three systems for warming intravenous fluids at different flow rates.

PubMed

Satoh, J; Yamakage, M; Wasaki, S I; Namiki, A

2006-02-01

This study compared the intravenous fluid warming capabilities of three systems at different flow rates. The devices studied were a water-bath warmer, a dry-heat plate warmer, and an intravenous fluid tube warmer Ambient temperature was controlled at 22 degrees to 24 degrees C. Normal saline (0.9% NaCl) at either room temperature (21 degrees to 23 degrees C) or at ice-cold temperature (3 degrees to 5 degrees C) was administered through each device at a range of flow rates (2 to 100 ml/min). To mimic clinical conditions, the temperature of the fluid was measured with thermocouples at the end of a one metre tube connected to the outflow of the warmer for the first two devices and at the end of the 1.2 m warming tubing for the intravenous fluid tube warmer The temperature of fluid delivered by the water bath warmer increased as the flow rate was increased up to 15 to 20 ml/min but decreased with greater flow rates. The temperature of the fluid delivered by the dry-heat plate warmer significantly increased as the flow rate was increased within the range tested (due to decreased cooling after leaving the device at higher flow rates). The temperature of fluid delivered by the intravenous fluid tube warmer did not depend on the flow rate up to 20 ml/min but significantly and fluid temperature-dependently decreased at higher flow rates (>30 ml/min). Under the conditions of our testing, the dry heat plate warmer delivered the highest temperature fluid at high flow rates.

The effect of storage temperature and duration on the microbial quality of bulk tank milk.

PubMed

O'Connell, A; Ruegg, P L; Jordan, K; O'Brien, B; Gleeson, D

2016-05-01

The dairy industry in Ireland is currently undergoing a period of expansion and, as a result, it is anticipated that milk may be stored in bulk tanks on-farm for periods greater than 48 h. The objective of this study was to investigate the effects of storage temperature and duration on microbial quality of bulk tank milk when fresh milk is added to the bulk tank twice daily. Bulk tank milk stored at 3 temperatures was sampled at 24-h intervals during storage periods of 0 to 96 h. Bulk tank milk samples were analyzed for total bacterial count (TBC), psychrotrophic bacterial count (PBC), laboratory pasteurization count (LPC), psychrotrophic-thermoduric bacterial count (PBC-LPC), proteolytic bacterial count, lipolytic bacterial count, presumptive Bacillus cereus, sulfite-reducing Clostridia (SRC), and SCC. The bulk tank milk temperature was set at each of 3 temperatures (2°C, 4°C, and 6°C) in each of 3 tanks on 2 occasions during two 6-wk periods. Period 1 was undertaken in August and September, when all cows were in mid lactation, and period 2 was undertaken in October and November, when all cows were in late lactation. None of the bulk tank bacterial counts except the proteolytic count were affected by lactation period. The proteolytic bacterial count was greater in period 2 than in period 1. The TBC and PBC of milk stored at 6°C increased as storage duration increased. The TBC did not increase with increasing storage duration when milk was stored at 2°C or 4°C but the PBC of milk stored at 4°C increased significantly between 0 and 96 h. The numbers of proteolytic and lipolytic bacteria, LPC, or PBC-LPC in bulk tank milk were not affected by temperature or duration of storage. Presumptive B. cereus were detected in 10% of all bulk tank milk samples taken over the two 6-wk periods, with similar proportions observed in both. In bulk tank milk samples, a greater incidence of SRC was observed in period 2 (20%) compared with period 1 (3%). Milk produced on-farm with minimal bacterial contamination can be successfully stored at 2°C and 4°C for up to 96h with little effect on its microbial quality. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Thermoelectric Generation Using Counter-Flows of Ideal Fluids

NASA Astrophysics Data System (ADS)

Meng, Xiangning; Lu, Baiyi; Zhu, Miaoyong; Suzuki, Ryosuke O.

2017-08-01

Thermoelectric (TE) performance of a three-dimensional (3-D) TE module is examined by exposing it between a pair of counter-flows of ideal fluids. The ideal fluids are thermal sources of TE module flow in the opposite direction at the same flow rate and generate temperature differences on the hot and cold surfaces due to their different temperatures at the channel inlet. TE performance caused by different inlet temperatures of thermal fluids are numerically analyzed by using the finite-volume method on 3-D meshed physical models and then compared with those using a constant boundary temperature. The results show that voltage and current of the TE module increase gradually from a beginning moment to a steady flow and reach a stable value. The stable values increase with inlet temperature of the hot fluid when the inlet temperature of cold fluid is fixed. However, the time to get to the stable values is almost consistent for all the temperature differences. Moreover, the trend of TE performance using a fluid flow boundary is similar to that of using a constant boundary temperature. Furthermore, 3-D contours of fluid pressure, temperature, enthalpy, electromotive force, current density and heat flux are exhibited in order to clarify the influence of counter-flows of ideal fluids on TE generation. The current density and heat flux homogeneously distribute on an entire TE module, thus indicating that the counter-flows of thermal fluids have high potential to bring about fine performance for TE modules.

The effect of storage conditions on the composition and functional properties of blended bulk tank milk.

PubMed

O'Connell, A; Kelly, A L; Tobin, J; Ruegg, P L; Gleeson, D

2017-02-01

The objective of this study was to investigate the effects of storage temperature and duration on the composition and functional properties of bulk tank milk when fresh milk was added to the bulk tank twice daily. The bulk tank milk temperature was set at each of 3 temperatures (2, 4, and 6°C) in each of 3 tanks on 2 occasions during two 6-wk periods. Period 1 was undertaken in August and September when all cows were in mid lactation, and period 2 was undertaken in October and November when all cows were in late lactation. Bulk tank milk stored at the 3 temperatures was sampled at 24-h intervals during storage periods of 0 to 96 h. Compositional parameters were measured for all bulk tank milk samples, including gross composition and quantification of nitrogen compounds, casein fractions, free amino acids, and Ca and P contents. The somatic cell count, heat stability, titratable acidity, and rennetability of bulk tank milk samples were also assessed. Almost all parameters differed between mid and late lactation; however, the interaction between lactation, storage temperature, and storage duration was significant for only 3 parameters: protein content and concentrations of free cysteic acid and free glutamic acid. The interaction between storage temperature and storage time was not significant for any parameter measured, and temperature had no effect on any parameter except lysine: lysine content was higher at 6°C than at 2°C. During 96 h of storage, the concentrations of some free amino acids (glutamic acid, lysine, and arginine) increased, which may indicate proteolytic activity during storage. Between 0 and 96 h, minimal deterioration was observed in functional properties (rennet coagulation time, curd firmness, and heat stability), which was most likely due to the dissociation of β-casein from the casein micelle, which can be reversed upon pasteurization. Thus, this study suggests that blended milk can be stored for up to 96 h at temperatures between 2°C and 6°C with little effect on its composition or functional properties. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Surface effects on friction-induced fluid heating in nanochannel flows.

PubMed

Li, Zhigang

2009-02-01

We investigate the mechanism of friction-induced fluid heating under the influence of surfaces. The temperature distributions of liquid argon and helium in nanoscale Poiseuille flows are studied through molecular dynamics simulations. It is found that the fluid heating is mainly caused by the viscous friction in the fluid when the external force is small and there is no slip at the fluid-solid interface. When the external force is larger than the fluid-surface binding force, the friction at the fluid-solid interface dominates over the internal friction of the fluid and is the major contribution to fluid heating. An asymmetric temperature gradient in the fluid is developed in the case of nonidentical walls and the general temperature gradient may change sign as the dominant heating factor changes from internal to interfacial friction with increasing external force. The effect of temperature on the fluid heating is also discussed.

Impact of Reservoir Fluid Saturation on Seismic Parameters: Endrod Gas Field, Hungary

NASA Astrophysics Data System (ADS)

El Sayed, Abdel Moktader A.; El Sayed, Nahla A.

2017-12-01

Outlining the reservoir fluid types and saturation is the main object of the present research work. 37 core samples were collected from three different gas bearing zones in the Endrod gas field in Hungary. These samples are belonging to the Miocene and the Upper - Lower Pliocene. These samples were prepared and laboratory measurements were conducted. Compression and shear wave velocity were measured using the Sonic Viewer-170-OYO. The sonic velocities were measured at the frequencies of 63 and 33 kHz for compressional and shear wave respectively. All samples were subjected to complete petrophysical investigations. Sonic velocities and mechanical parameters such as young’s modulus, rigidity, and bulk modulus were measured when samples were saturated by 100%-75%-0% brine water. Several plots have been performed to show the relationship between seismic parameters and saturation percentages. Robust relationships were obtained, showing the impact of fluid saturation on seismic parameters. Seismic velocity, Poisson’s ratio, bulk modulus and rigidity prove to be applicable during hydrocarbon exploration or production stages. Relationships among the measured seismic parameters in gas/water fully and partially saturated samples are useful to outline the fluid type and saturation percentage especially in gas/water transitional zones.

Systems and methods for thermal imaging technique for measuring mixing of fluids

DOEpatents

Booten, Charles; Tomerlin, Jeff; Winkler, Jon

2016-06-14

Systems and methods for thermal imaging for measuring mixing of fluids are provided. In one embodiment, a method for measuring mixing of gaseous fluids using thermal imaging comprises: positioning a thermal test medium parallel to a direction gaseous fluid flow from an outlet vent of a momentum source, wherein when the source is operating, the fluid flows across a surface of the medium; obtaining an ambient temperature value from a baseline thermal image of the surface; obtaining at least one operational thermal image of the surface when the fluid is flowing from the outlet vent across the surface, wherein the fluid has a temperature different than the ambient temperature; and calculating at least one temperature-difference fraction associated with at least a first position on the surface based on a difference between temperature measurements obtained from the at least one operational thermal image and the ambient temperature value.

Evaluation of outer race tilt and lubrication on ball wear and SSME bearing life reductions

NASA Technical Reports Server (NTRS)

Kannel, J. W.; Merriman, T. L.; Stockwell, R. D.; Dufrane, K. F.

1983-01-01

Several aspects of the SSME bearing operation were evaluated. The possibility of elastohydrodynamics (EHD) lubrication with a cryogenic fluid was analyzed. Films as thick as .61 microns were predicted with one theory which may be thick enough to provide hydrodynamic support. The film formation, however, is heavily dependent on good surface finish and a low bulk bearing temperature. Bearing dynamics to determine if the radial stiffness of a bearing which are dependent on bearing misalignment were analyzed. Four ball tests were conducted at several environmental conditions from an LN2 bath to 426 C in air. Surface coatings and ball materials are evaluated. Severe wear and high friction are measured for all ball materials except when the balls have surface lubricant coatings.

High Sensitivity Gravity Measurements in the Adverse Environment of Oil Wells

NASA Astrophysics Data System (ADS)

Pfutzner, Harold

2014-03-01

Bulk density is a primary measurement within oil and gas reservoirs and is the basis of most reserves calculations by oil companies. The measurement is performed with a gamma-ray source and two scintillation gamma-ray detectors from within newly drilled exploration and production wells. This nuclear density measurement, while very precise is also very shallow and is therefore susceptible to errors due to any alteration of the formation and fluids in the vicinity of the borehole caused by the drilling process. Measuring acceleration due to gravity along a well provides a direct measure of bulk density with a very large depth of investigation that makes it practically immune to errors from near-borehole effects. Advances in gravity sensors and associated mechanics and electronics provide an opportunity for routine borehole gravity measurements with comparable density precision to the nuclear density measurement and with sufficient ruggedness to survive the rough handling and high temperatures experienced in oil well logging. We will describe a borehole gravity meter and its use under very realistic conditions in an oil well in Saudi Arabia. The density measurements will be presented. Alberto Marsala (2), Paul Wanjau (1), Olivier Moyal (1), and Justin Mlcak (1); (1) Schlumberger, (2) Saudi Aramco.

Bulk modulus of two-dimensional liquid dusty plasmas and its application

NASA Astrophysics Data System (ADS)

Li, Wei; Lin, Wei; Feng, Yan

2017-04-01

From the recently obtained equation of state [Feng et al., J. Phys. D: Appl. Phys. 49, 235203 (2016) and Feng et al., Phys. Plasmas 23, 093705 (2016); Erratum 23, 119904 (2016)], the bulk modulus of elasticity K of 2D liquid dusty plasmas is analytically derived as the expression of the temperature and the screening parameter. Exact values of the obtained bulk modulus of elasticity K are reported and also plotted in the 2D plane of the temperature and the screening parameter. As the temperature and the screening parameter change, the variation trend of K is reported and the corresponding interpretation is suggested. It has been demonstrated that the obtained bulk modulus of elasticity K can be used to predict the longitudinal sound speed, which agrees well with previous studies.

Efficient bulk-loading of gridfiles

NASA Technical Reports Server (NTRS)

Leutenegger, Scott T.; Nicol, David M.

1994-01-01

This paper considers the problem of bulk-loading large data sets for the gridfile multiattribute indexing technique. We propose a rectilinear partitioning algorithm that heuristically seeks to minimize the size of the gridfile needed to ensure no bucket overflows. Empirical studies on both synthetic data sets and on data sets drawn from computational fluid dynamics applications demonstrate that our algorithm is very efficient, and is able to handle large data sets. In addition, we present an algorithm for bulk-loading data sets too large to fit in main memory. Utilizing a sort of the entire data set it creates a gridfile without incurring any overflows.

Live Soap: Stability, Order, and Fluctuations in Apolar Active Smectics

NASA Astrophysics Data System (ADS)

Adhyapak, Tapan Chandra; Ramaswamy, Sriram; Toner, John

2013-03-01

We construct a hydrodynamic theory of noisy, apolar active smectics in bulk suspension or on a substrate. Unlike purely orientationally ordered active fluids, active apolar smectics can be dynamically stable in Stokesian bulk suspensions. Smectic order in these systems is quasilong ranged in dimension d=2 and long ranged in d=3. We predict reentrant Kosterlitz-Thouless melting to an active nematic in our simplest model in d=2, a nonzero second-sound speed parallel to the layers in bulk suspensions, and that there are no giant number fluctuations in either case. We also briefly discuss possible instabilities in these systems.

Cooling system with automated seasonal freeze protection

DOEpatents

Campbell, Levi A.; Chu, Richard C.; David, Milnes P.; Ellsworth, Jr., Michael J.; Iyengar, Madhusudan K.; Simons, Robert E.; Singh, Prabjit; Zhang, Jing

2016-05-24

An automated multi-fluid cooling system and method are provided for cooling an electronic component(s). The cooling system includes a coolant loop, a coolant tank, multiple valves, and a controller. The coolant loop is at least partially exposed to outdoor ambient air temperature(s) during normal operation, and the coolant tank includes first and second reservoirs containing first and second fluids, respectively. The first fluid freezes at a lower temperature than the second, the second fluid has superior cooling properties compared with the first, and the two fluids are soluble. The multiple valves are controllable to selectively couple the first or second fluid into the coolant in the coolant loop, wherein the coolant includes at least the second fluid. The controller automatically controls the valves to vary first fluid concentration level in the coolant loop based on historical, current, or anticipated outdoor air ambient temperature(s) for a time of year.

Cooling method with automated seasonal freeze protection

DOEpatents

Cambell, Levi; Chu, Richard; David, Milnes; Ellsworth, Jr, Michael; Iyengar, Madhusudan; Simons, Robert; Singh, Prabjit; Zhang, Jing

2016-05-31

An automated multi-fluid cooling method is provided for cooling an electronic component(s). The method includes obtaining a coolant loop, and providing a coolant tank, multiple valves, and a controller. The coolant loop is at least partially exposed to outdoor ambient air temperature(s) during normal operation, and the coolant tank includes first and second reservoirs containing first and second fluids, respectively. The first fluid freezes at a lower temperature than the second, the second fluid has superior cooling properties compared with the first, and the two fluids are soluble. The multiple valves are controllable to selectively couple the first or second fluid into the coolant in the coolant loop, wherein the coolant includes at least the second fluid. The controller automatically controls the valves to vary first fluid concentration level in the coolant loop based on historical, current, or anticipated outdoor air ambient temperature(s) for a time of year.

Chemical, electronic, and magnetic structure of LaFeCoSi alloy: Surface and bulk properties

NASA Astrophysics Data System (ADS)

Lollobrigida, V.; Basso, V.; Borgatti, F.; Torelli, P.; Kuepferling, M.; Coïsson, M.; Olivetti, E. S.; Celegato, F.; Tortora, L.; Stefani, G.; Panaccione, G.; Offi, F.

2014-05-01

We investigate the chemical, electronic, and magnetic structure of the magnetocaloric LaFeCoSi compound with bulk and surface sensitive techniques. We put in evidence that the surface retains a soft ferromagnetic behavior at temperatures higher than the Curie temperature of the bulk due to the presence of Fe clusters at the surface only. This peculiar magnetic surface effect is attributed to the exchange interaction between the ferromagnetic Fe clusters located at the surface and the bulk magnetocaloric alloy, and it is used here to monitor the magnetic properties of the alloy itself.

Time-dependent compressibility of poly (methyl methacrylate) (PMMA) : an experimental and molecular dynamics investigation

NASA Astrophysics Data System (ADS)

Sane, Sandeep Bhalchandra

This thesis contains three chapters, which describe different aspects of an investigation of the bulk response of Poly(Methyl Methacrylate) (PMMA). The first chapter describes the physical measurements by means of a Belcher/McKinney-type apparatus. Used earlier for the measurement of the bulk response of Poly(Vinyl Acetate), it was now adapted for making measurements at higher temperatures commensurate with the glass transition temperature of PMMA. The dynamic bulk compliance of PMMA was measured at atmospheric pressure over a wide range of temperatures and frequencies, from which the master curves for the bulk compliance were generated by means of the time-temperature superposition principle. It was found that the extent of the transition ranges for the bulk and shear response were comparable. Comparison of the shift factors for bulk and shear responses supports the idea that different molecular mechanisms contribute to shear and bulk deformations. The second chapter delineates molecular dynamics computations for the bulk response for a range of pressures and temperatures. The model(s) consisted of 2256 atoms formed into three polymer chains with fifty monomer units per chain per unit cell. The time scales accessed were limited to tens of pico seconds. It was found that, in addition to the typical energy minimization and temperature annealing cycles for establishing equilibrium models, it is advantageous to subject the model samples to a cycle of relatively large pressures (GPa-range) for improving the equilibrium state. On comparing the computations with the experimentally determined "glassy" behavior, one finds that, although the computations were limited to small samples in a physical sense, the primary limitation rests in the very short times (pico seconds). The molecular dynamics computations do not model the physically observed temperature sensitivity of PMMA, even if one employs a hypothetical time-temperature shift to account for the large difference in time scales between experiment and computation. The values computed by the molecular dynamics method do agree with the values measured at the coldest temperature and at the highest frequency of one kiloHertz. The third chapter draws on measurements of uniaxial, shear and Poisson response conducted previously in our laboratory. With the availability of four time or frequency-dependent material functions for the same material, the process of interconversion between different material functions was investigated. Computed material functions were evaluated against the direct experimental measurements and the limitations imposed on successful interconversion due to the experimental errors in the underlying physical data were explored. Differences were observed that are larger than the experimental errors would suggest.

Comparison of urodynamic volume measurements using room and body temperature saline: a double-blinded randomized crossover study design.

PubMed

Gehrich, Alan Paul; Hill, Micah J; McWilliams, Grant D E; Larsen, Wilma; McCartin, Tamarin

2012-01-01

Urodynamic studies, routinely performed in women with lower urinary tract symptoms, have a large impact on clinical decision making. Unfortunately, these studies are insensitive in reproducing idiopathic detrusor overactivity (IDO). We set out to examine whether serial cystometry with different distending fluid temperatures could better reproduce symptoms. Eighty-six women were enrolled in a double-blinded, randomized, crossover study. Two cystometries were performed in series, starting with either body temperature fluid (BTF) or room temperature fluid (RTF) and then repeating cystometry with the other temperature fluid. Primary outcomes included first sensation, first urge, and maximum cystometric capacity. Secondary outcomes included subjective sensation of bladder discomfort and the incidence of IDO. In aggregate, the temperature of the fluid did not affect volumes of bladder sensation. There were no differences in self-reported bladder irritation or IDO between the different temperature fluids. There was a significant carryover effect with BTF. BTF administered first reached sensory thresholds at lower volumes than when it was administered second after RTF. Room temperature fluid cystometry showed no statistical difference in volume between first fill and second fill. Idiopathic detrusor overactivity contractions were seen in 9% of studies and were not affected by period or temperature. These data suggest that BTF and RTF independently do not affect bladder sensory thresholds. The periodicity in combination with varying fluid temperature is of greater impact. This study documents that changes in temperature of the distending fluid from BTF to RTF or vice versa likely do not provoke IDO contractions.

Relation Between Pore Size and the Compressibility of a Confined Fluid

PubMed Central

Gor, Gennady Y.; Siderius, Daniel W.; Rasmussen, Christopher J.; Krekelberg, William P.; Shen, Vincent K.; Bernstein, Noam

2015-01-01

When a fluid is confined to a nanopore, its thermodynamic properties differ from the properties of a bulk fluid, so measuring such properties of the confined fluid can provide information about the pore sizes. Here we report a simple relation between the pore size and isothermal compressibility of argon confined in these pores. Compressibility is calculated from the fluctuations of the number of particles in the grand canonical ensemble using two different simulation techniques: conventional grand-canonical Monte Carlo and grand-canonical ensemble transition-matrix Monte Carlo. Our results provide a theoretical framework for extracting the information on the pore sizes of fluid-saturated samples by measuring the compressibility from ultrasonic experiments. PMID:26590541

New views of granular mass flows

USGS Publications Warehouse

Iverson, R.M.; Vallance, J.W.

2001-01-01

Concentrated grain-fluid mixtures in rock avalanches, debris flows, and pyroclastic flows do not behave as simple materials with fixed rheologies. Instead, rheology evolves as mixture agitation, grain concentration, and fluid-pressure change during flow initiation, transit, and deposition. Throughout a flow, however, normal forces on planes parallel to the free upper surface approximately balance the weight of the superincumbent mixture, and the Coulomb friction rule describes bulk intergranular shear stresses on such planes. Pore-fluid pressure can temporarily or locally enhance mixture mobility by reducing Coulomb friction and transferring shear stress to the fluid phase. Initial conditions, boundary conditions, and grain comminution and sorting can influence pore-fluid pressures and cause variations in flow dynamics and deposits.

4D ERT-based calibration and prediction of biostimulant induced changes in fluid conductivity

NASA Astrophysics Data System (ADS)

Johnson, T. C.; Versteeg, R. J.; Day-Lewis, F. D.; Major, W. R.; Wright, K. E.

2008-12-01

In-situ bioremediation is an emerging and cost-effective method of removing organic contaminants from groundwater. The performance of bioremedial systems depends on the adequate delivery and distribution of biostimulants to contaminated zones. Monitoring the distribution of biostimulants using monitoring wells is expensive, time consuming, and provides inadequate information between sampling wells. We discuss a Hydrogeophysical Performance Monitoring System (HPMS) deployed to monitor bioremediation efforts at a TCE-contaminated Superfund site in Brandywine MD. The HPMS enables autonomous electrical geophysical data acquisition, processing, quality-assurance/quality-control, and inversion. Our objective is to demonstrate the feasibility and cost effectiveness of the HPMS to provide near real-time information on the spatiotemporal behavior of injected biostimulants. As a first step, we use time-lapse electrical resistivity tomography (ERT) to estimate changes in bulk conductivity caused by the injectate. We demonstrate how ERT-based bulk conductivity estimates can be calibrated with a small number of fluid conductivity measurements to produce ERT-based estimates of fluid conductivity. The calibration procedure addresses the spatially variable resolution of the ERT tomograms. To test the validity of these estimates, we used the ERT results to predict the fluid conductivity at tens of points prior to field sampling of fluid conductivity at the same points. The comparison of ERT-predicted vs. observed fluid conductivity displays a high degree of correlation (correlation coefficient over 0.8), and demonstrates the ability of the HPMS to estimate the four-dimensional (4D) distribution of fluid conductivity caused by the biostimulant injection.

Evaporation of liquid droplets of nano- and micro-meter size as a function of molecular mass and intermolecular interactions: experiments and molecular dynamics simulations.

PubMed

Hołyst, Robert; Litniewski, Marek; Jakubczyk, Daniel

2017-09-13

Transport of heat to the surface of a liquid is a limiting step in the evaporation of liquids into an inert gas. Molecular dynamics (MD) simulations of a two component Lennard-Jones (LJ) fluid revealed two modes of energy transport from a vapour to an interface of an evaporating droplet of liquid. Heat is transported according to the equation of temperature diffusion, far from the droplet of radius R. The heat flux, in this region, is proportional to temperature gradient and heat conductivity in the vapour. However at some distance from the interface, Aλ, (where λ is the mean free path in the gas), the temperature has a discontinuity and heat is transported ballistically i.e. by direct individual collisions of gas molecules with the interface. This ballistic transport reduces the heat flux (and consequently the mass flux) by the factor R/(R + Aλ) in comparison to the flux obtained from temperature diffusion. Thus it slows down the evaporation of droplets of sizes R ∼ Aλ and smaller (practically for sizes from 10 3 nm down to 1 nm). We analyzed parameter A as a function of interactions between molecules and their masses. The rescaled parameter, A(k B T b /ε 11 ) 1/2 , is a linear function of the ratio of the molecular mass of the liquid molecules to the molecular mass of the gas molecules, m 1 /m 2 (for a series of chemically similar compounds). Here ε 11 is the interaction parameter between molecules in the liquid (proportional to the enthalpy of evaporation) and T b is the temperature of the gas in the bulk. We tested the predictions of MD simulations in experiments performed on droplets of ethylene glycol, diethylene glycol, triethylene glycol and tetraethylene glycol. They were suspended in an electrodynamic trap and evaporated into dry nitrogen gas. A changes from ∼1 (for ethylene glycol) to approximately 10 (for tetraethylene glycol) and has the same dependence on molecular parameters as obtained for the LJ fluid in MD simulations. The value of x = A(k B T b /ε 11 ) 1/2 is of the order of 1 (for water x = 1.8, glycerol x = 1, ethylene glycol x = 0.4, tetraethylene glycol x = 2.1 evaporating into dry nitrogen at room temperature and for Lennard-Jones fluids x = 2 for m 1 /m 2 = 1 and low temperature).

Chlorine isotope constraints on fluid-rock interactions during subduction and exhumation of the Zermatt-Saas ophiolite

NASA Astrophysics Data System (ADS)

Selverstone, J.; Sharp, Z. D.

2013-10-01

Chlorine isotope compositions of high-pressure (˜2.3 GPa) serpentinite, rodingite, and hydrothermally altered oceanic crust (AOC) differ significantly from high- and ultrahigh-pressure (> 3.2 GPa) metasedimentary rocks in the Aosta region, Italy. Texturally early serpentinites, rodingites, and AOC have bulk δ37Cl values indistinguishable from those of modern seafloor analogues (δ37Cl = -1.0 to +1.0‰). In contrast, serpentinites and AOC samples that recrystallized during exhumation have low δ37Cl values (-2.7 to -0.5‰); 37Cl depletion correlates with progressive changes in bulk chemistry. HP/UHP metasediments have low δ37Cl values (median = -2.5‰) that differ statistically from modern marine sediments (median = -0.6‰). Cl in metasedimentary rocks is concentrated in texturally early minerals, indicating modification of seafloor compositions early in the subduction history. The data constrain fluid sources during both subduction and exhumation-related phases of fluid-rock interaction: (1) marine sediments at the top of the downgoing plate likely interacted with isotopically light pore fluids from the accretionary wedge in the early stages of subduction. (2) No pervasive interaction with externally derived fluid occurred during subsequent subduction to the maximum depths of burial. (3) Localized mixing between serpentinites and fluids released by previously isotopically modified metasediments occurred during exhumation in the subduction channel. Most samples, however, preserved protolith signatures during subduction to near-arc depths.

ROOM TEMPERATURE BULK AND TEMPLATE-FREE SYNTHESIS OF LEUCOEMARLDINE POLYANILINE NANOFIBERS

EPA Science Inventory

Herein, we describe a simple strategy for the bulk and template-free synthesis of reduced leucoemarldine polyaniline nanofibers size ranging from as low as 10 nm to 50 nm without the use of any reducing agents at room temperature.

Correlated Time-Variation of Asphalt Rheology and Bulk Microstructure

NASA Astrophysics Data System (ADS)

Ramm, Adam; Nazmus, Sakib; Bhasin, Amit; Downer, Michael

We use noncontact optical microscopy and optical scattering in the visible and near-infrared spectrum on Performance Grade (PG) asphalt binder to confirm the existence of microstructures in the bulk. The number of visible microstructures increases linearly as penetration depth of the incident radiation increases, which verifies a uniform volume distribution of microstructures. We use dark field optical scatter in the near-infrared to measure the temperature dependent behavior of the bulk microstructures and compare this behavior with Dynamic Shear Rheometer (DSR) measurements of the bulk complex shear modulus | G* (T) | . The main findings are: (1) After reaching thermal equilibrium, both temperature dependent optical scatter intensity (I (T)) and bulk shear modulus (| G* (T) |) continue to change appreciably for times much greater than thermal equilibration times. (2) The hysteresis behavior during a complete temperature cycle seen in previous work derives from a larger time dependence in the cooling step compared with the heating step. (3) Different binder aging conditions show different thermal time-variations for both I (T) and | G* (T) | .

Single Crystal Synthesis and STM Studies of High Temperature Superconductors

NASA Technical Reports Server (NTRS)

Barrientos, Alfonso

1997-01-01

This is a final report for the work initiated in September of 1994 under the grant NAG8-1085 - NASA/OMU, on the fabrication of bulk and single crystal synthesis, specific heat measuring and STM studies of high temperature superconductors. Efforts were made to fabricate bulk and single crystals of mercury based superconducting material. A systematic thermal analysis on the precursors for the corresponding oxides and carbonates were carried out to synthesized bulk samples. Bulk material was used as seed in an attempt to grow single crystals by a two-step self flux process. On the other hand bulk samples were characterized by x-ray diffraction, electrical resistivity and magnetic susceptibility, We studied the specific heat behavior in the range from 80 to 300 K. Some preliminary attempts were made to study the atomic morphology of our samples. As part of our efforts we built an ac susceptibility apparatus for measuring the transition temperature of our sintered samples.

High-Oriented Thermoelectric Nano-Bulk Fabricated from Thermoelectric Ink

NASA Astrophysics Data System (ADS)

Koyano, M.; Mizutani, S.; Hayashi, Y.; Nishino, S.; Miyata, M.; Tanaka, T.; Fukuda, K.

2017-05-01

Printing technology is expected to provide innovative and environmentally friendly processes for thermoelectric (TE) module fabrication. As described in this paper, we propose an orientation control process using plastic deformation at high temperatures and present high-oriented TE nano-bulks fabricated from bismuth telluride (Bi-Te) TE inks using this process. In the case of n-type Bi-Te, surface x-ray diffraction reveals that crystalline grains in the plastic-deformed nano-bulk demonstrate a c-plane orientation parallel to the pressed face. According to the high orientation, electrical resistivity ρ, thermal conductivity κ, and figure of merit ZT show anisotropic behavior. It is noteworthy that ( ZT)// almost reaches unity ( ZT)// ˜1 at 340 K, even at low temperatures of the plastic deformation process. In contrast, the ZT of plastic-deformed p-type nano-bulk indicates isotropic behavior. The difference in the process temperature dependence of ZT suggests that n-type and p-type nano-bulk orientation mechanisms mutually differ.

Differences in SOM decomposition and temperature sensitivity among soil aggregate size classes in a temperate grasslands.

PubMed

Wang, Qing; Wang, Dan; Wen, Xuefa; Yu, Guirui; He, Nianpeng; Wang, Rongfu

2015-01-01

The principle of enzyme kinetics suggests that the temperature sensitivity (Q10) of soil organic matter (SOM) decomposition is inversely related to organic carbon (C) quality, i.e., the C quality-temperature (CQT) hypothesis. We tested this hypothesis by performing laboratory incubation experiments with bulk soil, macroaggregates (MA, 250-2000 μm), microaggregates (MI, 53-250 μm), and mineral fractions (MF, <53 μm) collected from an Inner Mongolian temperate grassland. The results showed that temperature and aggregate size significantly affected on SOM decomposition, with notable interactive effects (P<0.0001). For 2 weeks, the decomposition rates of bulk soil and soil aggregates increased with increasing incubation temperature in the following order: MA>MF>bulk soil >MI(P <0.05). The Q10 values were highest for MA, followed (in decreasing order) by bulk soil, MF, and MI. Similarly, the activation energies (Ea) for MA, bulk soil, MF, and MI were 48.47, 33.26, 27.01, and 23.18 KJ mol-1, respectively. The observed significant negative correlations between Q10 and C quality index in bulk soil and soil aggregates (P<0.05) suggested that the CQT hypothesis is applicable to soil aggregates. Cumulative C emission differed significantly among aggregate size classes (P <0.0001), with the largest values occurring in MA (1101 μg g-1), followed by MF (976 μg g-1) and MI (879 μg g-1). These findings suggest that feedback from SOM decomposition in response to changing temperature is closely associated withsoil aggregation and highlights the complex responses of ecosystem C budgets to future warming scenarios.

Mechanisms for the Crystallization of ZBLAN

NASA Technical Reports Server (NTRS)

Ethridge, Edwin C.; Tucker, Dennis S.; Kaukler, William; Antar, Basil

2003-01-01

The objective of this ground based study is to test the hypothesis that shear thinning (the non-Newtonian response of viscosity to shear rate) is a viable mechanism to explain the observation of enhanced glass formation in numerous low-g experiments. In 1-g, fluid motion results from buoyancy forces and surface tension driven convection. This fluid flow will introduce shear in undercooled liquids in 1-g. In low-g it is known that fluid flows are greatly reduced so that the shear rate in fluids can be extremely low. It is believed that some fluids may have weak structure in the absence of flow. Very small shear rates could cause this structure to collapse in response to shear resulting in a lowering of the viscosity of the fluid. The hypothesis of this research is that: Shear thinning in undercooled liquids decreases the viscosity, increasing the rate of nucleation and crystallization of glass forming melts. Shear in the melt can be reduced in low-g, thus enhancing undercooling and glass formation. The viscosity of a model glass (lithium di-silicate, L2S) often used for crystallization studies has been measured at very low shear rates using a dynamic mechanical thermal analyzer. Our results are consistent with increasing viscosity with a lowering of shear rates. The viscosity of L2S may vary as much as an order of magnitude depending on the shear rate in the temperature region of maximum nucleation and crystal growth. Classical equations for nucleation and crystal growth rates, are inversely related to the viscosity and viscosity to the third power respectively. An order of magnitude variation in viscosity (with shear) at a given temperature would have dramatic effects on glass crystallization Crystallization studies with the heavy metal fluoride glass ZBLAN (ZrF2-BaF2-LaF3-AlF3-NaF) to examine the effect of shear on crystallization are being initiated. Samples are to be melted and quenched under quiescent conditions at different shear rates to determine the effect on crystallization. The results from this study are expected to advance the current scientific understanding of glass formation in low-g and glass crystallization under glass molding conditions and will improve the scientific understanding of technological processes such as fiber pulling, bulk amorphous alloys, and glass fabrication processes.

Rapid microfluidic thermal cycler for nucleic acid amplification

DOEpatents

Beer, Neil Reginald; Vafai, Kambiz

2015-10-27

A system for thermal cycling a material to be thermal cycled including a microfluidic heat exchanger; a porous medium in the microfluidic heat exchanger; a microfluidic thermal cycling chamber containing the material to be thermal cycled, the microfluidic thermal cycling chamber operatively connected to the microfluidic heat exchanger; a working fluid at first temperature; a first system for transmitting the working fluid at first temperature to the microfluidic heat exchanger; a working fluid at a second temperature, a second system for transmitting the working fluid at second temperature to the microfluidic heat exchanger; a pump for flowing the working fluid at the first temperature from the first system to the microfluidic heat exchanger and through the porous medium; and flowing the working fluid at the second temperature from the second system to the heat exchanger and through the porous medium.

Nusselt number and bulk temperature in turbulent Rayleigh-Bénard convection

NASA Astrophysics Data System (ADS)

Bodenschatz, Eberhard; Weiss, Stephan; Shishkina, Olga; International CollaborationTurbulence Research Collaboration

2017-11-01

We present an algorithm to calculate the Nusselt number (Nu) in measurements of the heat transport in turbulent Rayleigh-Bénard convection under general non-Oberbeck-Boussinesq (NOB) conditions. We further critically analyze the different ways to evaluate the dependences of Nu over the Rayleigh number (Ra) and show the sensitivity of these dependences to the reference temperatures in the bulk, top and bottom boundary layers (BLs). Finally we propose a method to predict the bulk temperature and a way to calculate the reference temperatures of the top and bottom BLs and validate them against the Göttingen measurements. The work is supported by the Max Planck Society and the Deutsche Forschungsgemeinschaft (DFG) under the Grant Sh 405/4 - Heisenberg fellowship.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Glynos, Emmanouil; Johnson, Kyle J.; Frieberg, Bradley

The surface relaxation dynamics of supported star-shaped polymer thin films are shown to be slower than the bulk, persisting up to temperatures at least 50 K above the bulk glass transition temperature Tgbulk. This behavior, exhibited by star-shaped polystyrenes with functionality f=8 arms and molecular weights per arm Marm

Effects of Temperature and Supply Voltage on SEU- and SET-Induced Errors in Bulk 40-nm Sequential Circuits

NASA Astrophysics Data System (ADS)

Chen, R. M.; Diggins, Z. J.; Mahatme, N. N.; Wang, L.; Zhang, E. X.; Chen, Y. P.; Zhang, H.; Liu, Y. N.; Narasimham, B.; Witulski, A. F.; Bhuva, B. L.; Fleetwood, D. M.

2017-08-01

The single-event sensitivity of bulk 40-nm sequential circuits is investigated as a function of temperature and supply voltage. An overall increase in SEU cross section versus temperature is observed at relatively high supply voltages. However, at low supply voltages, there is a threshold temperature beyond which the SEU cross section decreases with further increases in temperature. Single-event transient induced errors in flip-flops also increase versus temperature at relatively high supply voltages and are more sensitive to temperature variation than those caused by single-event upsets.

Optimum free energy in the reference functional approach for the integral equations theory

NASA Astrophysics Data System (ADS)

Ayadim, A.; Oettel, M.; Amokrane, S.

2009-03-01

We investigate the question of determining the bulk properties of liquids, required as input for practical applications of the density functional theory of inhomogeneous systems, using density functional theory itself. By considering the reference functional approach in the test particle limit, we derive an expression of the bulk free energy that is consistent with the closure of the Ornstein-Zernike equations in which the bridge functions are obtained from the reference system bridge functional. By examining the connection between the free energy functional and the formally exact bulk free energy, we obtain an improved expression of the corresponding non-local term in the standard reference hypernetted chain theory derived by Lado. In this way, we also clarify the meaning of the recently proposed criterion for determining the optimum hard-sphere diameter in the reference system. This leads to a theory in which the sole input is the reference system bridge functional both for the homogeneous system and the inhomogeneous one. The accuracy of this method is illustrated with the standard case of the Lennard-Jones fluid and with a Yukawa fluid with very short range attraction.

Surfactant effects on the dynamics of an intravascular bubble

NASA Astrophysics Data System (ADS)

Zhang, Jie; Eckmann, David; Ayyaswamy, P. S.

2004-11-01

The effects of a surfactant on the dynamics of gas bubble behavior in the arteriolar vasculature are numerically investigated. The equations for momentum in the bulk fluid (blood) and the bubble, and the convection-diffusion equations for mass transport both in the bulk fluid and on the gas-liquid interface are numerically solved using a front tracking method. Both soluble and insoluble surfactants are considered. The adsorption/desorption dynamics of the soluble surfactant is accurately resolved. For a nearly occluded bubble, a faster rate of depletion of the surfactant from the region adjacent to the wall of the vessel is observed. In several cases studied here, the bulk medium is treated as non-Newtonian (power law, Casson), although the majority of cases treat blood as Newtonian. Results show that the adsorbed surfactant serves to prevent blood proteins and other macromolecules from occupying the interface. This prevents clotting or adhesion of the bubble to the vessel wall. The results obtained have significance in the study of intravascular gas embolism. Supported by NIH R01 HL67986

Tribological characterisation of Zr-based bulk metallic glass in simulated physiological media

NASA Astrophysics Data System (ADS)

Chen, Q.; Chan, K. C.; Liu, L.

2011-10-01

Due to their excellent wear resistant properties and high strength, as well as a low Young's modulus, Zr-based bulk metallic glasses (BMGs) are potentially suitable biomaterials for low-friction arthroplasty. The wear characteristics of the Zr60.14Cu22.31Fe4.85Al9.7Ag3 bulk amorphous alloy against ultra-high-molecular-weight polyethylene (UHMWPE) compared to a CoCrMo/UHMWPE combination were investigated in two different wear screening test devices, reciprocating and unidirectional. Hank's solution and sterile calf bovine serum were selected as the lubricant fluid media. It was found that different fluid media had insignificant effect on polyethylene wear against BMG counterfaces. The wear behaviour obtained on both test devices demonstrated that Zr-based BMG achieved UHMWPE counterface wear rates superior to conventional cast CoCrMo alloy, where the wear rate of UHMWPE is decreased by over 20 times. The tribological performance of these joints is superior to that of conventional metal-on-polymer designs. Contact angle measurements suggested that the advantage of BMG over a CoCrMo alloy counterface is attributed to its highly hydrophilic surfaces.

The dissolution of calcite in CO2-saturated solutions at 25°C and 1 atmosphere total pressure

USGS Publications Warehouse

Plummer, Niel; Wigley, T.M.L.

1976-01-01

The dissolution of Iceland spar in CO2-saturated solutions at 25°C and 1 atm total pressure has been followed by measurement of pH as a function of time. Surface concentrations of reactant and product species have been calculated from bulk fluid data using mass transport theory and a model that accounts for homogeneous reactions in the bulk fluid. The surface concentrations are found to be close to bulk solution values. This indicates that calcite dissolution under the experimental conditions is controlled by the kinetics of surface reaction. The rate of calcite dissolution follows an empirical second order relation with respect to calcium and hydrogen ion from near the initial condition (pH 3.91) to approximately pH 5.9. Beyond pH 5.9 the rate of surface reaction is greatly reduced and higher reaction orders are observed. Calculations show that the rate of calcite dissolution in natural environments may be influenced by both transport and surface-reaction processes. In the absence of inhibition, relatively short times should be sufficient to establish equilibrium.

Northwest Africa 5738: Multistage fluid-driven secondary alteration in an extraordinarily evolved eucrite

NASA Astrophysics Data System (ADS)

Warren, Paul H.; Rubin, Alan E.; Isa, Junko; Gessler, Nicholas; Ahn, Insu; Choi, Byeon-Gak

2014-09-01

The Northwest Africa 5738 eucrite contains a record of unprecedented geochemical complexity for a sample from the HED asteroid. It originated with a uniquely evolved (Stannern Trend) primary igneous composition, combining ultra-high bulk incompatible element and Na2O concentrations with a relatively low mg. Its bulk oxygen-isotopic composition (Δ‧17O = -0.27‰), as well as its trace element composition (e.g., Ga/Al), confirm other evidence for classification as a eucrite. Pyroxene mg equilibration, exsolution and ;cloudy; inclusions, all reflect a typical eucritic degree of thermal metamorphism. The rock contains an unprecedented array of microscopic fluid-metasomatic vein deposits. Most common are curvy microveins within pyroxene, which consist dominantly of Ca-plagioclase (typically An95, in stark contrast with the rock's An68-78 primary-igneous plagioclase), with Fe-olivine (Fo14) and Cr-spinel as additional major constituents. Likely related to these microveins are small masses of intergrown Ca-plagioclase (again roughly An95) and silica (or high-Si glass). Analyses of the microvein Cr-spinels show stoichiometry implying a significant Fe3+ content (Fe2O3 0.7-2.3 wt.%), and fO2 up to roughly IW+3; clearly elevated in comparison to the normal HED fO2 of about IW-1. The fO2 results show an anticorrelation with equilibration T (and with Mg/Fe), which suggests the parent fluid system became more oxidizing as it cooled. NWA 5738 also contains apparent secondary iron metal. The Fe-metals are very pure, with Ni consistently below an EPMA detection limit of ∼0.01 wt.%. The vein-like shapes of roughly 1/3 of the largest Fe-metals suggest origin by deposition from a fluid. The role of pyroxene exsolution as template for a denticular (sawtooth) Fe-metal edge shape, and the survival of Fo14 olivine in a rock with abundant silica and a far higher bulk mg, suggest that the most intense thermal metamorphism occurred no later than the secondary alteration. Near-complete lack of spatial association suggests that the Fe-metals formed during a distinct time period from the curvy microveins. The immediate cause of Fe-metal deposition was most plausibly (or anyway, least implausibly) an abrupt downshift in the fluid fO2. Considering the extremely evolved bulk composition, the fluid(s) may have been largely deuteric. However, more likely the main source of fluid was a nearby buried mass of volatile-rich impactor matter, such as carbonaceous chondrite, that hit the asteroid at low enough velocity to remain mostly intact. We further speculate that the abrupt drop in fluid fO2 may have been caused by a process of carbon-fueled ;smelting; (cf. ureilites), triggered by an impact-effected shift of the carbonaceous material to a changed environment, with higher T and/or lower P. These and other recent eucrite results point to a need for greater scrutiny regarding the absence of comparable alteration-veining in rocks from the lunar highland crust, a mysterious lack in view of recent evidence for abundant lunar water.

Bulk-Flow Analysis of Hybrid Thrust Bearings for Advanced Cryogenic Turbopumps

NASA Technical Reports Server (NTRS)

SanAndres, Luis

1998-01-01

A bulk-flow analysis and computer program for prediction of the static load performance and dynamic force coefficients of angled injection, orifice-compensated hydrostatic/hydrodynamic thrust bearings have been completed. The product of the research is an efficient computational tool for the design of high-speed thrust bearings for cryogenic fluid turbopumps. The study addresses the needs of a growing technology that requires of reliable fluid film bearings to provide the maximum operating life with optimum controllable rotordynamic characteristics at the lowest cost. The motion of a cryogenic fluid on the thin film lands of a thrust bearing is governed by a set of bulk-flow mass and momentum conservation and energy transport equations. Mass flow conservation and a simple model for momentum transport within the hydrostatic bearing recesses are also accounted for. The bulk-flow model includes flow turbulence with fluid inertia advection, Coriolis and centrifugal acceleration effects on the bearing recesses and film lands. The cryogenic fluid properties are obtained from realistic thermophysical equations of state. Turbulent bulk-flow shear parameters are based on Hirs' model with Moody's friction factor equations allowing a simple simulation for machined bearing surface roughness. A perturbation analysis leads to zeroth-order nonlinear equations governing the fluid flow for the thrust bearing operating at a static equilibrium position, and first-order linear equations describing the perturbed fluid flow for small amplitude shaft motions in the axial direction. Numerical solution to the zeroth-order flow field equations renders the bearing flow rate, thrust load, drag torque and power dissipation. Solution to the first-order equations determines the axial stiffness, damping and inertia force coefficients. The computational method uses well established algorithms and generic subprograms available from prior developments. The Fortran9O computer program hydrothrust runs on a Windows 95/NT personal computer. The program, help files and examples are licensed by Texas A&M University Technology License Office. The study of the static and dynamic performance of two hydrostatic/hydrodynamic bearings demonstrates the importance of centrifugal and advection fluid inertia effects for operation at high rotational speeds. The first example considers a conceptual hydrostatic thrust bearing for an advanced liquid hydrogen turbopump operating at 170,000 rpm. The large axial stiffness and damping coefficients of the bearing should provide accurate control and axial positioning of the turbopump and also allow for unshrouded impellers, therefore increasing the overall pump efficiency. The second bearing uses a refrigerant R134a, and its application in oil-free air conditioning compressors is of great technological importance and commercial value. The computed predictions reveal that the LH2 bearing load capacity and flow rate increase with the recess pressure (i.e. increasing orifice diameters). The bearing axial stiffness has a maximum for a recess pressure rati of approx. 0.55. while the axial damping coefficient decreases as the recess pressure ratio increases. The computer results from three flow models are compared. These models are a) inertialess, b) fluid inertia at recess edges only, and c) full fluid inertia at both recess edges and film lands. The full inertia model shows the lowest flow rates, axial load capacity and stiffness coefficient but on the other hand renders the largest damping coefficients and inertia coefficients. The most important findings are related to the reduction of the outflow through the inner radius and the appearance of subambient pressures. The performance of the refrigerant hybrid thrust bearing is evaluated at two operating speeds and pressure drops. The computed results are presented in dimensionless form to evidence consistent trends in the bearing performance characteristics. As the applied axial load increases, the bearing film thickness and flow rate decrease while the recess pressure increases. The axial stiffness coefficient shows a maximum for a certain intermediate load while the damping coefficient steadily increases. The computed results evidence the paramount of centrifugal fluid inertia at low recess pressures (i.e. low loads), and where there is actually an inflow through the bearing inner diameter, accompanied by subambient pressures just downstream of the bearing recess edge. These results are solely due to centrifugal fluid inertia and advection transport effects. Recommendations include the extension of the computer program to handle flexure pivot tilting pad hybrid bearings and the ability to calculate moment coefficients for shaft angular misalignments.

Synthesis of formamidinium lead iodide perovskite bulk single crystal and its optical properties

NASA Astrophysics Data System (ADS)

Zheng, Hongge; Duan, Junjie; Dai, Jun

2017-07-01

Formamidinium lead iodide (FAPbI3) is a promising hybrid perovskite material for optoelectronic devices. We synthesized bulk single crystal FAPbI3 by a rapid solution crystallization method. X-ray diffraction (XRD) was performed to characterize the crystal structure. Temperature-dependent photoluminescence (PL) spectra of the bulk single crystal FAPbI3 were measured from 10 to 300 K to explain PL recombination mechanism. It shows that near band edge emission blueshifts with the temperature increasing from 10 to 120 K and from 140 K to room temperature, a sudden emission band redshift demonstrates near 140 K because of the phase transition from orthorhombic phase to cubic phase. From the temperature-dependent PL spectra, the temperature coefficients of the bandgap and thermal activation energies of FAPbI3 perovskite are fitted.

Analytical Prediction of Motor Component Vibrations Driven by Acoustic Combustion Instability

DTIC Science & Technology

1976-02-01

27"V 1Sy 1 2 oiihedr41 Symmetry .. .. . ., . . C-28 3 SPCD Bulk Data Card Format ......... . . .. .- 29 4 CYJOIN Bulk Data Card Format...analysis, the loads, the values of enforced displacements, and the temperatures may vary from element to element. The SPCD bulk data card (Figure 3) is...Static loads for vech suhc’: -e are spcified with LOAD, ’TEMPERATURE (LOAD), or DE .-I, oiectic.-,!•. Enforced deformations may be specified on SPCD

Magnetic Resonance of Polymers at Surfaces

DTIC Science & Technology

1989-08-28

are similar in their response to solvent Znd temperature in bulk poly(vinyl acetate) ( PVAc ). 2 5 This technique has been used for comparison with bulk...polymer for the PVAc -silica and polystyrene (PS)-silica systems. 2 6 As a function of temperature, comparison of the surface labelled polymer with the...the coverage was increased, the ESR spectra of the polymer also became more bulk-like. The mobility of the PVAc on silica was also shown to depend on

A randomised single blinded study of the administration of pre-warmed fluid vs active fluid warming on the incidence of peri-operative hypothermia in short surgical procedures.

PubMed

Andrzejowski, J C; Turnbull, D; Nandakumar, A; Gowthaman, S; Eapen, G

2010-09-01

We compared the effect of delivering fluid warmed using two methods in 76 adult patients having short duration surgery. All patients received a litre of crystalloid delivered either at room temperature, warmed using an in-line warming device or pre-warmed in a warming cabinet for at least 8 h. The tympanic temperature of those receiving fluid at room temperature was 0.4 °C lower on arrival in recovery when compared with those receiving fluid from a warming cabinet (p = 0.008). Core temperature was below the hypothermic threshold of 36.0 °C in seven (14%) patients receiving either type of warm fluid, compared to eight (32%) patients receiving fluid at room temperature (p = 0.03). The administration of 1 l warmed fluid to patients having short duration general anaesthesia results in higher postoperative temperatures. Pre-warmed fluid, administered within 30 min of its removal from a warming cabinet, is as efficient at preventing peri-operative hypothermia as that delivered through an in-line warming system. © 2010 The Authors. Journal compilation © 2010 The Association of Anaesthetists of Great Britain and Ireland.

Study on Combustion Characteristics and Propelling Projectile Motion Process of Bulk-Loaded Liquid Propellant

NASA Astrophysics Data System (ADS)

Xue, Xiaochun; Yu, Yonggang; Mang, Shanshan

2017-07-01

Data are presented showing that the problem of gas-liquid interaction instability is an important subject in the combustion and the propellant projectile motion process of a bulk-loaded liquid propellant gun (BLPG). The instabilities themselves arise from the sources, including fluid motion, to form a combustion gas cavity called Taylor cavity, fluid turbulence and breakup caused by liquid motion relative to the combustion chamber walls, and liquid surface breakup arising from a velocity mismatch on the gas-liquid interface. Typically, small disturbances that arise early in the BLPG combustion interior ballistic cycle can become amplified in the absence of burn rate limiting characteristics. Herein, significant attention has been given to developing and emphasizing the need for better combustion repeatability in the BLPG. Based on this goal, the concept of using different geometries of the combustion chamber is introduced and the concept of using a stepped-wall structure on the combustion chamber itself as a useful means of exerting boundary control on the combustion evolution to thus restrain the combustion instability has been verified experimentally in this work. Moreover, based on this background, the numerical simulation is devoted to a special combustion issue under transient high-pressure and high-temperature conditions, namely, studying the combustion mechanism in a stepped-wall combustion chamber with full monopropellant on one end that is stationary and the other end can move at high speed. The numerical results also show that the burning surface of the liquid propellant can be defined geometrically and combustion is well behaved as ignition and combustion progressivity are in a suitable range during each stage in this combustion chamber with a stepped-wall structure.

Scalable Nernst thermoelectric power using a coiled galfenol wire

NASA Astrophysics Data System (ADS)

Yang, Zihao; Codecido, Emilio A.; Marquez, Jason; Zheng, Yuanhua; Heremans, Joseph P.; Myers, Roberto C.

2017-09-01

The Nernst thermopower usually is considered far too weak in most metals for waste heat recovery. However, its transverse orientation gives it an advantage over the Seebeck effect on non-flat surfaces. Here, we experimentally demonstrate the scalable generation of a Nernst voltage in an air-cooled metal wire coiled around a hot cylinder. In this geometry, a radial temperature gradient generates an azimuthal electric field in the coil. A Galfenol (Fe0.85Ga0.15) wire is wrapped around a cartridge heater, and the voltage drop across the wire is measured as a function of axial magnetic field. As expected, the Nernst voltage scales linearly with the length of the wire. Based on heat conduction and fluid dynamic equations, finite-element method is used to calculate the temperature gradient across the Galfenol wire and determine the Nernst coefficient. A giant Nernst coefficient of -2.6 μV/KT at room temperature is estimated, in agreement with measurements on bulk Galfenol. We expect that the giant Nernst effect in Galfenol arises from its magnetostriction, presumably through enhanced magnon-phonon coupling. Our results demonstrate the feasibility of a transverse thermoelectric generator capable of scalable output power from non-flat heat sources.

Finite Atwood Number Effects on Deceleration-Phase Instability in Room-Temperature Direct-Drive Implosions

NASA Astrophysics Data System (ADS)

Miller, S.; Knauer, J. P.; Radha, P. B.; Goncharov, V. N.

2017-10-01

Performance degradation in direct-drive inertial confinement fusion implosions can be caused by several effects, one of which is Rayleigh-Taylor (RT) instability growth during the deceleration phase. In room-temperature plastic target implosions, this deceleration-phase RT growth is enhanced by the density discontinuity and finite Atwood numbers at the fuel-pusher interface. For the first time, an experimental campaign at the Omega Laser Facility systematically varied the ratio of deuterium-to-tritium (D-to-T) within the DT gas fill to change the Atwood number. The goal of the experiment was to understand the effects of Atwood number variation on observables like apparent ion temperature, yield, and variations in areal density and bulk fluid motion, which lead to broadening of neutron spectra along different lines of sight. Simulations by the hydrodynamic codes LILAC and DRACO were used to study growth rates for different D-to-T ratios and identify observable quantities effected by Atwood number variation. Results from simulations and the experiment are presented. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

Widespread hydrothermal alteration minerals in the fine-grained matrices of the Tieschitz unequilibrated ordinary chondrite

NASA Astrophysics Data System (ADS)

Dobricǎ, E.; Brearley, A. J.

2014-08-01

Mineralogic, textural, and compositional studies of black and white matrices in the unequilibrated ordinary chondrite Tieschitz (H/L, 3.6) show, for the first time in an ordinary chondrite, the presence of widespread, randomly distributed geode-like voids and veins. Scanning electron microscope (SEM) and transmission electron microscope (TEM) studies show that these voids and veins are partially or completely filled by sodic-calcic amphiboles (winchite and barroisite). The occurrence of amphiboles provides unequivocal evidence of the involvement of fluids in the metamorphic evolution of the parent body of Tieschitz. The presence of amphiboles as the main hydrous phases, rather than phyllosilicates, indicates that aqueous fluids were present at or close to the peak of thermal metamorphism, rather than during the waning stages of the cooling history of the parent body. In addition, ferrous olivine crystals, in association with the amphibole, also establish an important link between thermal metamorphism and hydrous phases formed at high temperatures. Mineralogic and textural evidence suggests that the white matrix and amphibole formed contemporaneously from the same hydrous fluid, prior to the formation of ferrous olivine crystals. Additionally, a dark inclusion identified in the host chondrite has mineralogic, petrologic, and bulk chemical characteristics that are similar to the black matrix of host Tieschitz, suggesting that this dark inclusion was emplaced before or during parent body metamorphism.

Study of flow fractionation characteristics of magnetic chromatography utilizing high-temperature superconducting bulk magnet.

PubMed

Fukui, Satoshi; Shoji, Yoshihiro; Ogawa, Jun; Oka, Tetsuo; Yamaguchi, Mitsugi; Sato, Takao; Ooizumi, Manabu; Imaizumi, Hiroshi; Ohara, Takeshi

2009-02-01

We present numerical simulation of separating magnetic particles with different magnetic susceptibilities by magnetic chromatography using a high-temperature superconducting bulk magnet. The transient transport is numerically simulated for two kinds of particles having different magnetic susceptibilities. The time evolutions were calculated for the particle concentration in the narrow channel of the spiral arrangement placed in the magnetic field. The field is produced by the highly magnetized high-temperature superconducting bulk magnet. The numerical results show the flow velocity difference of the particle transport corresponding to the difference in the magnetic susceptibility, as well as the possible separation of paramagnetic particles of 20 nm diameter.

Temperature Dependent Electrical Properties of PZT Wafer

NASA Astrophysics Data System (ADS)

Basu, T.; Sen, S.; Seal, A.; Sen, A.

2016-04-01

The electrical and electromechanical properties of lead zirconate titanate (PZT) wafers were investigated and compared with PZT bulk. PZT wafers were prepared by tape casting technique. The transition temperature of both the PZT forms remained the same. The transition from an asymmetric to a symmetric shape was observed for PZT wafers at higher temperature. The piezoelectric coefficient (d 33) values obtained were 560 pc/N and 234 pc/N, and the electromechanical coupling coefficient (k p) values were 0.68 and 0.49 for bulk and wafer, respectively. The reduction in polarization after fatigue was only ~3% in case of PZT bulk and ~7% for PZT wafer.

Effect of Sn addition on glassy Si-Te bulk sample

NASA Astrophysics Data System (ADS)

Babanna, Jagannatha K.; Roy, Diptoshi; Varma, Sreevidya G.; Asokan, Sundarrajan; Das, Chandasree

2018-05-01

Bulk Si20Te79Sn1 glass is prepared by melt-quenching method, amorphous nature of the as-quenched glass is confirmed by XRD. I-V characteristics reveals that Si20Te79Sn1 bulk sample exhibits threshold type electrical switching behavior. The thermal parameters such as crystallization temperature, glass transition temperature are obtained using differential scanning calorimetry. The crystalline peak study of the sample annealed at crystallization temperature for 2 hr shows that the Sn atom interact with Si or Te but do not interact with the Si-Te matrix in a greater extent and it forms a separate phase network individually.

In-line bulk supersaturation measurement by electrical conductometry in KDP crystal growth from aqueous solution

NASA Astrophysics Data System (ADS)

Bordui, P. F.; Loiacono, G. M.

1984-07-01

A method is presented for in-line bulk supersaturation measurement in crystal growth from aqueous solution. The method is based on a computer-controlled concentration measurement exploiting an experimentally predetermined cross-correlation between the concentration, electrical conductivity, and temperature of the growth solution. The method was applied to Holden crystallization of potassium dihydrogen phosphate (KDP). An extensive conductivity-temperature-concentration data base was generated for this system over a temperature range of 31 to 41°C. The method yielded continous, automated bulk supersaturation output accurate to within ±0.05 g KDP100 g water (±0.15% relative supersaturation).

Fully-Coupled Fluid/Structure Vibration Analysis Using MSC/NASTRAN

NASA Technical Reports Server (NTRS)

Fernholz, Christian M.; Robinson, Jay H.

1996-01-01

MSC/NASTRAN's performance in the solution of fully-coupled fluid/structure problems is evaluated. NASTRAN is used to perform normal modes (SOL 103) and forced-response analyses (SOL 108, 111) on cylindrical and cubic fluid/structure models. Bulk data file cards unique to the specification of a fluid element are discussed and analytic partially-coupled solutions are derived for each type of problem. These solutions are used to evaluate NASTRAN's solutions for accuracy. Appendices to this work include NASTRAN data presented in fringe plot form, FORTRAN source code listings written in support of this work, and NASTRAN data file usage requirements for each analysis.

Holographic anyonic superfluidity

NASA Astrophysics Data System (ADS)

Jokela, Niko; Lifschytz, Gilad; Lippert, Matthew

2013-10-01

Starting with a holographic construction for a fractional quantum Hall state based on the D3-D7' system, we explore alternative quantization conditions for the bulk gauge fields. This gives a description of a quantum Hall state with various filling fractions. For a particular alternative quantization of the bulk gauge fields, we obtain a holographic anyon fluid in a vanishing background magnetic field. We show that this system is a superfluid, exhibiting the relevant gapless excitation.

Using Mason number to predict MR damper performance from limited test data

NASA Astrophysics Data System (ADS)

Becnel, Andrew C.; Wereley, Norman M.

2017-05-01

The Mason number can be used to produce a single master curve which relates MR fluid stress versus strain rate behavior across a wide range of shear rates, temperatures, and applied magnetic fields. As applications of MR fluid energy absorbers expand to a variety of industries and operating environments, Mason number analysis offers a path to designing devices with desired performance from a minimal set of preliminary test data. Temperature strongly affects the off-state viscosity of the fluid, as the passive viscous force drops considerably at higher temperatures. Yield stress is not similarly affected, and stays relatively constant with changing temperature. In this study, a small model-scale MR fluid rotary energy absorber is used to measure the temperature correction factor of a commercially-available MR fluid from LORD Corporation. This temperature correction factor is identified from shear stress vs. shear rate data collected at four different temperatures. Measurements of the MR fluid yield stress are also obtained and related to a standard empirical formula. From these two MR fluid properties - temperature-dependent viscosity and yield stress - the temperature-corrected Mason number is shown to predict the force vs. velocity performance of a full-scale rotary MR fluid energy absorber. This analysis technique expands the design space of MR devices to high shear rates and allows for comprehensive predictions of overall performance across a wide range of operating conditions from knowledge only of the yield stress vs. applied magnetic field and a temperature-dependent viscosity correction factor.

Experimental investigation of the flow dynamics and rheology of complex fluids in pipe flow by hybrid multi-scale velocimetry

NASA Astrophysics Data System (ADS)

Haavisto, Sanna; Cardona, Maria J.; Salmela, Juha; Powell, Robert L.; McCarthy, Michael J.; Kataja, Markku; Koponen, Antti I.

2017-11-01

A hybrid multi-scale velocimetry method utilizing Doppler optical coherence tomography in combination with either magnetic resonance imaging or ultrasound velocity profiling is used to investigate pipe flow of four rheologically different working fluids under varying flow regimes. These fluids include water, an aqueous xanthan gum solution, a softwood fiber suspension, and a microfibrillated cellulose suspension. The measurement setup enables not only the analysis of the rheological (bulk) behavior of a studied fluid but gives simultaneously information on their wall layer dynamics, both of which are needed for analyzing and solving practical fluid flow-related problems. Preliminary novel results on rheological and boundary layer flow properties of the working fluids are reported and the potential of the hybrid measurement setup is demonstrated.

Opto-mechano-fluidic viscometer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, Kewen, E-mail: khan56@illinois.edu; Zhu, Kaiyuan; Bahl, Gaurav, E-mail: bahl@illinois.edu

2014-07-07

The recent development of opto-mechano-fluidic resonators has provided—by harnessing photon radiation pressure—a microfluidics platform for the optical sensing of fluid density and bulk modulus. Here, we show that fluid viscosity can also be determined through optomechanical measurement of the vibrational noise spectrum of the resonator mechanical modes. A linear relationship between the spectral linewidth and root-viscosity is predicted and experimentally verified in the low viscosity regime. Our result is a step towards multi-frequency measurement of viscoelasticity of arbitrary fluids, without sample contamination, using highly sensitive optomechanics techniques.

Partitioning of tritium between surface and bulk of 316 stainless steel at room temperature

DOE PAGES

Sharpe, M. D.; Fagan, C.; Shmayda, W. T.; ...

2018-03-28

The distribution of tritium between the near surface and the bulk of 316 stainless steel has been measured using two independent techniques: pulsed-plasma exposures and a zinc-chloride wash. Between 17% and 20% of the total inventory absorbed into a stainless-steel sample during a 24-h exposure to DT gas at room temperature resides in the water layers present on the metal surface. Redistribution of tritium between the surface and the bulk of stainless steel, if it occurs, is very slow. Finally, tritium does not appear to enter into the bulk at a rate defined solely by lattice diffusivity.

Partitioning of tritium between surface and bulk of 316 stainless steel at room temperature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharpe, M. D.; Fagan, C.; Shmayda, W. T.

The distribution of tritium between the near surface and the bulk of 316 stainless steel has been measured using two independent techniques: pulsed-plasma exposures and a zinc-chloride wash. Between 17% and 20% of the total inventory absorbed into a stainless-steel sample during a 24-h exposure to DT gas at room temperature resides in the water layers present on the metal surface. Redistribution of tritium between the surface and the bulk of stainless steel, if it occurs, is very slow. Finally, tritium does not appear to enter into the bulk at a rate defined solely by lattice diffusivity.

Simultaneous thermodynamic and geochemical analyses for P-T-time and mass transport toward comprehensive understanding of metamorphism

NASA Astrophysics Data System (ADS)

Uno, M.; Nakamura, H.; Iwamori, H.

2011-12-01

Individual parcel of regional metamorphic rock records physico-chemical conditions such as P-T path, mass transfer and deformation with the Lagrangian specification. On the other hand, a metamorphic belt as an ensemble of such parcels may provide a large-scale flow field of energy (e.g., temperature, entropy) and mass (including both solid and fluid phases with elements and isotopes) with the Eulerian specification. However, there is so far few model that integrates all the variables stated above. Phase petrology provides mostly the intensive variables (e.g., P-T path), whereas geochemistry provides mostly the extensive variables (time-integrated mass transfer), and these two have been treated separately. Here we combine phase petrology and geochemistry from a scale of mineral grain, and solve them under a simultaneous and consistent set of thermodynamic and mass balance equation. For this sake, the Sanbagawa metamorphic belt in Japan has been surveyed. To understand the nature of fluid during rehydration, we analyzed both basic rocks and pelitic rocks that record retrograde reactions. Major and trace element compositions of each mineral, and bulk rock chemistry have been analyzed with EPMA, LA-ICP-MS, XRF and ICP-MS, respectively. Retrograde P-T path and the extent of rehydration of each rock have been obtained by applying the Gibbs' method (e.g. Spear, 1993; Okamoto&Toriumi, 2001) to amphiboles. Trace element budget along a specific P-T path were calculated by equating differential mass balance equation for major and trace elements as follows; XfluiddMfluid = ⊙MsolidXsolid + ⊙XsoliddMsolid Where the X and M denotes compositions and modes of minerals and dX and dM are their changes along a specific P-T change. The mineral compositions (Xsolid), mineral modes (Msolid), mineral growths (dMsolid) for zoned minerals (amphibole and/or garnet) and fluid compositions (Xfluid) were derived from the results of Gibbs' method, X-ray map and fluid/mineral partition coefficients, respectively. Thus, the unknowns are dMs, and the equations are solved for them. As a result, the mass transfer during the specific P-T change (Xfluid dMfluid) can be specified. It is revealed that fluid mobile elements such as LIL elements, Sr and Pb are mostly proportional to LOI (loss on ignition). LOI and extent of rehydration is proportional in the Sanbagawa belt (Okamoto&Toriumi, 2005), thus the observed enrichment of LILE, Sr and Pb are interpreted to be associated with rehydration. The Sr isotope ratios of the basic shists also increase with LOI, implying that the differences in bulk rock chemistry are not attributed to differences in mineral modes,but addition and/or reaction with external source of fluids with high 87Sr/86Sr. The estimated fluid composition is similar to calculated compositions of slab-derived fluids (Nakamura et al., 2008). From mass balance calculation, trace element budget associated with rehydration reactions and their spatial distribution will be presented, and the mechanisms of mass and fluid transfer will be discussed.

Solids mass flow determination

DOEpatents

Macko, Joseph E.

1981-01-01

Method and apparatus for determining the mass flow rate of solids mixed with a transport fluid to form a flowing mixture. A temperature differential is established between the solids and fluid. The temperature of the transport fluid prior to mixing, the temperature of the solids prior to mixing, and the equilibrium temperature of the mixture are monitored and correlated in a heat balance with the heat capacities of the solids and fluid to determine the solids mass flow rate.

Laminar flow studies of a low-temperature space radiator model using D-shaped tubes

NASA Technical Reports Server (NTRS)

Cintula, T. C.; Prok, G. M.; Johnston, D. B.

1972-01-01

Test results of a low-temperature space radiator model are presented. Radiator performance is evaluated with a low-thermal-conductivity fluid in laminar flow in D-shaped cross-section tubes. The test covered a Reynolds number range from 50 to 4500 and a fluid temperature range from 294 to 414 K (70 to 286 F). For low-temperature radiators, the fluid-to-surface temperature differential was predominately influenced by fluid temperature in laminar flow. Heat transfer and pressure drop for the radiator tube could be predicted within engineering accuracy from existing correlations.

Traction and lubricant film temperature as related to the glass transition temperature and solidification. [using infrared spectroscopy on EHD contacts

NASA Technical Reports Server (NTRS)

Lauer, J. L.; Peterkin, M. E.

1978-01-01

Does a traction fluid have to be a glass or solid under operating conditions. Infrared spectra on dynamic EHD contacts of several types of fluid were used to determine the surface and oil-film temperatures. Polarized spectral runs were made to study molecular alignment. Static glass transition pressures at appropriate temperatures were between 0.1 and 2.0 GPa, with the traction fluid showing the highest. In the EHD contact region, the traction fluid showed both the highest film temperatures as well as the greatest degree of molecular alignment. A plot of the difference between the film and surface temperatures vs shear rate resulted in a master plot valid for all the fluids. From this work, the authors propose a model of 'fluid' traction, where friction between parallel rough molecules provides the traction.

Petrologic and chemical changes in ductile shear zones as a function of depth in the continental crust

NASA Astrophysics Data System (ADS)

Yang, Xin-Yue

Petrologic and geochemical changes in ductile shear zones are important for understanding deformational and geochemical processes of the continental crust. This study examines three shear zones that formed under conditions varying from lower greenschist facies to upper amphibolite facies in order to document the petrologic and geochemical changes of deformed rocks at various metamorphic grades. The studied shear zones include two greenschist facies shear zones in the southern Appalachians and an upper amphibolite facies shear zone in southern Ontario. The mylonitic gneisses and mylonites in the Roses Mill shear zone of central Virginia are derived from a ferrodiorite protolith and characterized by a lower greenschist facies mineral assemblage. Both pressure solution and recrystallization were operative deformation mechanisms during mylonitization in this shear zone. Strain-driven dissolution and solution transfer played an important role in the mobilization of felsic components (Si, Al, K, Na, and Ca). During mylonitization, 17% to 32% bulk rock volume losses of mylonites are mainly attributed to removal of these mobile felsic components by a fluid phase. Mafic components (Fe, Mg, Ti, Mn and P) and trace elements, REE, Y, V and Sc, were immobile. At Rosman, North Carolina, the Brevard shear zone (BSZ) shows a deformational transition from the coarse-grained Henderson augen gneiss (HAG) to proto-mylonite, mylonite and ultra-mylonite. The mylonites contain a retrograde mineral assemblage as a product of fluid-assisted chemical breakdown of K-feldspar and biotite at higher greenschist facies conditions. Recrystallization and intra-crystalline plastic deformation are major deformation mechanisms in the BSZ. Fluid-assisted mylonitization in the BSZ led to 6% to 23% bulk volume losses in mylonites. During mylonitization, both major felsic and mafic elements and trace elements, Rb, Sr, Zr, V, Sc, and LREE were mobile; however, the HREEs were likely immobile. A shear zone in the Parry Sound domain, Ontario, formed at upper amphibolite facies conditions. The deformation process of the shear zone involves fully plastic deformation and high-temperature dynamic recrystallization and annealing recovery of both quartz and plagioclase. Geochemical evidence indicates that the chemical changes in the deformed rocks resulted from mixing of mafic and felsic layers together with fluid-assisted mass transfer within the shear zone. A geochemical model that incorporates closed-system two-component mixing with open-system mass transfer can well explain the observed major and trace element data.

Serpentinization and fluid-rock interaction in Jurassic mafic and ultramafic sea-floor: constraints from Ligurian ophiolite sequences

NASA Astrophysics Data System (ADS)

Vogel, Monica; Früh-Green, Gretchen L.; Boschi, Chiara; Schwarzenbach, Esther M.

2014-05-01

The Bracco-Levanto ophiolitic complex (Eastern Liguria) represents one of the largest and better-exposed ophiolitic successions in the Northern Apennines. It is considered to be a fragment of heterogeneous Jurassic lithosphere that records tectono-magmatic and alteration histories similar to those documented along the Mid-Atlantic Ridge, such as at the 15°20'N area and the Atlantis Massif at 30°N. Structural and petrological studies on these rocks provide constraints on metamorphic/deformation processes during formation and hydrothermal alteration of the Jurassic oceanic lithosphere. We present a petrological and geochemical study of deformation processes and fluid-rock interaction in the Bracco-Levanto ophiolitic complex and compare these to modern oceanic hydrothermal systems, such as the Lost City Hydrothermal Field hosted in ultramafic rocks on the Atlantis Massif. A focus is on investigating mass transfer and fluid flow paths during high and low temperature hydrothermal activity, and on processes leading to hydrothermal carbonate precipitation and the formation of ophicalcites, which are characteristic of the Bracco-Levanto sequences. Major element and mineral compositional data allow us to distinguish a multiphase history of alteration characterized by: (1) widespread SiO2 metasomatism during progressive serpentinization, and (2) multiple phases of veining and carbonate precipitation associated with circulation of seawater and high fluid-rock ratios in the shallow ultramafic-dominated portions of the Jurassic seafloor. We observe regional variations in MgO, SiO2 and Al2O3, suggesting Si-flux towards stratigraphically higher units. In general, the ophicalcites have higher Si, Al and Fe concentrations and lower Mg than the serpentinite basement rocks or serpentinites with minimal carbonate veins. Bulk rock trace element data and Sr isotope ratios indicate seawater reacting with rocks of more mafic composition, then channeled towards stratigraphically higher units, leading to Si metasomatism in the serpentinites and ophicalcites. Channelling of Si-rich fluids is also indicated by amphibole and talc growth in shear zones and wall rock around the ophicalcites. δ18O-values of the carbonate veins indicate temperatures up to 150°C and document a decrease in temperature with ongoing serpentinization. Comparison with serpentinites from the Atlantis Massif and 15°20'N indicates a similar degree of Si enrichment in the modern seafloor and suggests that Si-metasomatism may be a fundamental process associated with serpentinization at slow-spreading ridge environments.

Modern water/rock reactions in Oman hyperalkaline peridotite aquifers and implications for microbial habitability

NASA Astrophysics Data System (ADS)

Miller, Hannah M.; Matter, Jürg M.; Kelemen, Peter; Ellison, Eric T.; Conrad, Mark E.; Fierer, Noah; Ruchala, Tyler; Tominaga, Masako; Templeton, Alexis S.

2016-04-01

The Samail ophiolite in Oman is undergoing modern hydration and carbonation of peridotite and may host a deep subsurface biosphere. Previous investigations of hyperalkaline fluids in Oman have focused on fluids released at surface seeps, which quickly lose their reducing character and precipitate carbonates upon contact with the O2/CO2-rich atmosphere. In this work, geochemical analysis of rocks and fluids from the subsurface provides new insights into the operative reactions in serpentinizing aquifers. Serpentinite rock and hyperalkaline fluids (pH > 10), which exhibit millimolar concentrations of Ca2+, H2 and CH4, as well as variable sulfate and nitrate, were accessed from wells situated in mantle peridotite near Ibra and studied to investigate their aqueous geochemistry, gas concentrations, isotopic signatures, mineralogy, Fe speciation and microbial community composition. The bulk mineralogy of drill cuttings is dominated by olivine, pyroxene, brucite, serpentine and magnetite. At depth, Fe-bearing brucite is commonly intermixed with serpentine, whereas near the surface, olivine and brucite are lost and increased magnetite and serpentine is detected. Micro-Raman spectroscopy reveals at least two distinct generations of serpentine present in drill cuttings recovered from several depths from two wells. Fe K-edge X-ray absorption near-edge spectroscopy (XANES) analysis of the lizardite shows a strong tetrahedral Fe coordination, suggesting a mixture of both Fe(II) and Fe(III) in the serpentine. Magnetite veins are also closely associated with this second generation serpentine, and 2-10 μm magnetite grains overprint all minerals in the drill cuttings. Thus we propose that the dissolved H2 that accumulates in the subsurface hyperalkaline fluids was evolved through low temperature oxidation and hydration of relict olivine, as well as destabilization of pre-existing brucite present in the partially serpentinized dunites and harzburgites. In particular, we hypothesize that Fe-bearing brucite is currently reacting with dissolved silica in the aquifer fluids to generate late-stage magnetite, additional serpentine and dissolved H2. Dissolved CH4 in the fluids exhibits the most isotopically heavy carbon in CH4 reported in the literature thus far. The CH4 may have formed through abiotic reduction of dissolved CO2 or through biogenic pathways under extreme carbon limitation. The methane isotopic composition may have also been modified by significant methane oxidation. 16S rRNA sequencing of DNA recovered from filtered hyperalkaline well fluids reveals an abundance of Meiothermus, Thermodesulfovibrionaceae (sulfate-reducers) and Clostridia (fermenters). The fluids also contain candidate phyla OP1 and OD1, as well as Methanobacterium (methanogen) and Methylococcus sp. (methanotroph). The composition of these microbial communities suggests that low-temperature hydrogen and methane generation, coupled with the presence of electron acceptors such as nitrate and sulfate, sustains subsurface microbial life within the Oman ophiolite.

Kinetic multi-layer model of the epithelial lining fluid (KM-ELF): Reactions of ozone and OH with antioxidants and surfactant molecules

NASA Astrophysics Data System (ADS)

Lakey, Pascale; Pöschl, Ulrich; Shiraiwa, Manabu

2015-04-01

Oxidants cause damage to biosurfaces such as the lung epithelium unless they are effectively scavenged. The respiratory tract is covered in a thin layer of fluid which extends from the nasal cavity to the alveoli and contain species that scavenge ozone and other incoming oxidants. The kinetic multi-layer model of the epithelial lining fluid (KM-ELF) has been developed in order to investigate the reactions of ozone and OH with antioxidants (ascorbate, uric acid, glutathione and α-tocopherol) and surfactant lipids and proteins within the epithelial lining fluid (ELF). The model incorporates different processes: gas phase diffusion, adsorption and desorption from the surface, bulk phase diffusion and known reactions at the surface and in the bulk. The ELF is split into many layers: a sorption layer, a surfactant layer, a near surface bulk layer and several bulk layers. Initial results using KM-ELF indicate that at ELF thicknesses of 80 nm and 1 × 10-4cm the ELF would become rapidly saturated with ozone with saturation occurring in less than a second. However, at an ELF thickness of 1 × 10-3cm concentration gradients were observed throughout the ELF and the presence of antioxidants reduced the O3 reaching the lung cells and tissues by 40% after 1 hour of exposure. In contrast, the antioxidants were efficient scavengers of OH radicals, although the large rate constants of OH reacting with the antioxidants resulted in the antioxidants decaying away rapidly. The chemical half-lives of the antioxidants and surface species were also calculated using KM-ELF as a function of O3 and OH concentration and ELF thickness. Finally, the pH dependence of the products of reactions between antioxidants and O3 were investigated. The KM-ELF model predicted that a harmful ascorbate ozonide product would increase from 1.4 × 1011cm-3at pH 7.4 to 1.1 × 1014 cm-3 at pH 4after 1 hour although a uric acid ozonide product would decrease from 2.0 × 1015cm-3to 5.9 × 1012cm-3.

Cryogenic refrigeration apparatus

DOEpatents

Crunkleton, James A.

1992-01-01

A technique for producing a cold environment in a refrigerant system in which input fluid from a compressor at a first temperature is introduced into an input channel of the system and is pre-cooled to a second temperature for supply to one of at least two stages of the system, and to a third temperature for supply to another stage thereof. The temperatures at such stages are reduced to fourth and fifth temperatures below the second and third temperatures, respectively. Fluid at the fourth temperature from the one stage is returned through the input channel to the compressor and fluid at the fifth temperature from the other stage is returned to the compressor through an output channel so that pre-cooling of the input fluid to the one stage occurs by regenerative cooling and counterflow cooling and pre-cooling of the input fluid to the other stage occurs primarily by counterflow cooling.