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Sample records for free-surface lithium flow

  1. Incompressible Flows Free Surfaces

    Energy Science and Technology Software Center (ESTSC)

    1992-02-01

    NASA-VOF3D is a three-dimensional, transient, free surface, incompressible fluid dynamics program. It is specifically designed to calculate confined flows in a low gravity environment in which surface physics must be accurately treated. It allows multiple free surfaces with surface tension and wall adhesion and includes a partial cell treatment that allows curved boundaries and internal obstacles. Variable mesh spacing is permitted in all three coordinate directions. Boundary conditions available are rigid free-slip wall, rigid no-slipmore » wall, continuative, periodic, and specified pressure outflow boundary.« less

  2. Retention/Diffusivity Studies in Free-Surface Flowing Liquid Lithium

    SciTech Connect

    R.A. Stubbers; G.H. Miley; M. Nieto; W. Olczak; D.N. Ruzic; A. Hassanein

    2004-12-14

    FLIRE was designed to measure the hydrogen and helium retention and diffusivity in a flowing stream of liquid lithium, and it has accomplished these goals. Retention coefficients for helium in the flowing liquid stream were 0.1-2% for flow speeds of 44 cm/s and implantation energies between 500 and 2000 eV. The energy dependence of retention is linear for the energy range considered, as expected, and the dependence of retention on flow velocity fits the expected square-root of flow speed dependence. Estimates of the helium diffusion coefficient in the flowing lithium stream were {approx} 4 x 10{sup -7} cm{sup 2}/s, and are independent of implantation energy. This value is much lower than expected, which could be due to several factors, such as mixing, bubble formation or surface film formation. In the case of hydrogen, long term retention and release mechanisms are of greatest importance, since this relates to tritium inventory in flowing lithium PFCs for fusion applications. The amount of hydride formation was measured for flowing lithium exposed to neutral deuterium gas. Thermal desorption spectroscopy (TDS) measurements indicate that the hydride concentration was between 0.1 and 0.2% over a wide range of pressures (6.5 x 10{sup -5} to 1 Torr). This result implies that the deuterium absorption rate is limited by the surface dissociation rate, since deuterium (hydrogen/tritium) is absorbed in its atomic form, not its molecular form.

  3. Computing Incompressible Flows With Free Surfaces

    NASA Technical Reports Server (NTRS)

    Kothe, D.

    1994-01-01

    RIPPLE computer program models transient, two-dimensional flows of incompressible fluids with surface tension on free surfaces of general shape. Surface tension modeled as volume force derived from continuum-surface-force model, giving RIPPLE both robustness and accuracy in modeling surface-tension effects at free surface. Also models wall adhesion effects. Written in FORTRAN 77.

  4. Natural Elements Method for Free Surface Flow

    NASA Astrophysics Data System (ADS)

    Darbani, M.; Ouahsine, A.; Villon, P.

    2009-09-01

    The Natural Element Method (NEM) is used to simulate a 2D shallow water flow in presence of free surface and a varying bathymetry. This meshless method used a fully Lagrangian formulation and natural neighbors, which remain a very striking problem related the boundary conditions. The method was succefully used to simulate dam-break flows by solving the fully nonlinear Shallow Water Equations (SWE) and by using an implicit scheme under a transient flow and the Coriolis effect.

  5. Finite element solutions of free surface flows

    NASA Technical Reports Server (NTRS)

    Zarda, P. R.; Marcus, M. S.

    1977-01-01

    A procedure is presented for using NASTRAN to determine the flow field about arbitrarily shaped bodies in the presence of a free surface. The fundamental unknown of the problem is the velocity potential which must satisfy Laplace's equation in the fluid region. Boundary conditions on the free surface may involve second order derivatives in space and time. In cases involving infinite domains either a tractable radiation condition is applied at a truncated boundary or a series expansion is used and matched to the local finite elements. Solutions are presented for harmonic, transient, and steady state problems and compared to either exact solutions or other numerical solutions.

  6. Free-surface and coating flows

    NASA Astrophysics Data System (ADS)

    Ashmore, Jacqueline

    In thus thesis we present results on four problems which fall into the class of free-surface flows. Two of the problems relate to coating flows, in which a thin film of fluid is deposited on a moving substrate. The third problem concerns the motion of a sphere down an inclined plane that is coated with a thin film of viscous fluid. Finally, we study the Rayleigh capillary instability of a cylindrical fluid thread surrounded by a second viscous fluid in a rotating frame. One useful tool for analysis of coating flows is the method of matched asymptotics, which enables us to obtain a solution to the nonlinear third-order differential equation that describes the free-surface shape in two of the problems we study. The first coating flow problem we consider is the interface shape of fluid inside a horizontal cylinder rotating about its axis with a small fraction of its volume filled with viscous Newtonian fluid. By accounting for surface tension effects we find a new axially uniform steady solution valid at low rotation rates. Predictions for the scalings based on matched asymptotic methods are confirmed numerically. Secondly, theoretical predictions of the film thickness that coats a substrate when it is withdrawn from a bath of viscoelastic fluid are presented, for a number of substrate geometries. In the third problem studied, we use lubrication analysis to characterize the steady translational velocity and rotation rate of a sphere that moves down an inclined plane, which is coated with a thin film of fluid, under the action of gravity. In this case, an understanding of the fluid flow must be used to determine the forces that act on the sphere, which set the translational speed and rotation rate of the sphere. Finally, we study the effect of the Coriolis force on the Rayleigh capillary instability of a cylindrical column of viscous liquid surrounded by a second viscous liquid in a rotating frame. Our study comprises numerical results of a temporal linear stability

  7. PIV measurements of flow around an arbitrarily moving free surface

    NASA Astrophysics Data System (ADS)

    Park, Jinsoo; Im, Sunghyuk; Sung, Hyung Jin; Park, Jun Sang

    2015-03-01

    We present an image preprocessing method for particle image velocimetry (PIV) measurements of flow around an arbitrarily moving free surface. When performing PIV measurements of free surface flows, the interrogation windows neighboring the free surface are vulnerable to a lack, or even an absence, of seeding particles, which induces less reliable measurements of the velocity field. In addition, direct measurements of the free surface velocity using PIV have been challenging due to the intermittent appearance of the arbitrarily moving free surface. To address the aforementioned limitations, the PIV images with a curvilinear free surface can be treated to be suitable for a structured interrogation window arrangement in a Cartesian grid. The proposed image preprocessing method is comprised of a free surface detection method and an image transform process. The free surface position was identified using a free surface detection method based on multiple textons. The detected free surface points were used to transform PIV images of a curvilinear free surface into images with a straightened free surface using a cubic Hermite spline interpolation scheme. After the image preprocessing, PIV algorithms can be applied to the treated PIV images. The fluid-only region velocities were measured using standard PIV method with window deformation, and the free surface velocities were resolved using PIV/interface gradiometry method. The velocity field in the original PIV images was constructed by inverse transforming that in the transformed images. The accuracy of the proposed method was quantitatively evaluated with two sets of synthetic PIV images, and its applicability was examined by applying the present method to free surface flow images, specifically sloshing flow images.

  8. RIPPLE - A new model for incompressible flows with free surfaces

    NASA Technical Reports Server (NTRS)

    Kothe, D. B.; Mjolsness, R. C.

    1991-01-01

    A new free surface flow model, RIPPLE, is summarized. RIPPLE obtains finite difference solutions for incompressible flow problems having strong surface tension forces at free surfaces of arbitrarily complex topology. The key innovation is the continuum surface force model which represents surface tension as a (strongly) localized volume force. Other features include a higher-order momentum advection model, a volume-of-fluid free surface treatment, and an efficient two-step projection solution method. RIPPLE's unique capabilities are illustrated with two example problems: low-gravity jet-induced tank flow, and the collision and coalescence of two cylindrical rods.

  9. Free-Surface Induced Axial Flows in Oscillating Cylinder Wakes

    NASA Astrophysics Data System (ADS)

    Voorhees, A. V.; Wei, T.

    1999-11-01

    The problem to be discussed is that of the effect of a free surface on flow along the cores of Karman vortices shed from an inverted pendulum type cylinder. The motivation for this research was to determine the nature and extent of free surface effects in flow induced vibrations of structures aligned perpendicular to and penetrating a free surface. The 2.54 cm diameter cylinder studied had a low mass ratio and was attached at the bottom end by a leaf spring; the free, upper end protruded through the free surface of a large water tunnel. It has been observed that the vortex induced oscillations of the cylinder resulted in very strong axial flows upward toward the free surface, even for small amplitude motions. Approaching the free surface, however, there was an equal likelyhood that the axial flows would be directed down away from the surface. The connection between the direction of axial flow and the cylinder motion will be described using single and two view flow visualization techniques.

  10. Application of the PTT model to axisymmetric free surface flows

    NASA Astrophysics Data System (ADS)

    Merejolli, R.; Paulo, G. S.; Tomé, M. F.

    2013-10-01

    This work is concerned with numerical simulation of axisymmetric viscoelastic free surface flows using the Phan-Thien-Tanner (PTT) constitutive equation. A finite difference technique for solving the governing equations for unsteady incompressible flows written in Cylindrical coordinates on a staggered grid is described. The fluid is modelled by a Marker-and-Cell type method and an accurate representation of the fluid surface is employed. The full free surface stress conditions are applied. The numerical method is verified by comparing numerical predictions of fully developed flow in a pipe with the corresponding analytic solutions. To demonstrate that the numerical method can simulate axisymmetric free surface flows governed by the PTT model, numerical results of the flow evolution of a drop impacting on a rigid dry plate are presented. In these simulations, the rheological effects of the parameters ɛ and ξ are investigated.

  11. Energy-decomposition analysis for viscous free-surface flows.

    PubMed

    Colagrossi, Andrea; Bouscasse, Benjamin; Marrone, Salvatore

    2015-11-01

    This work is dedicated to the energy decomposition analysis of a viscous free-surface flow. In the presence of a free surface, the viscous dissipation for a Newtonian liquid can be decomposed into two terms: an enstrophy component and a free-surface deformation component. The latter requires the evaluation of volume and surface integrals in the meshless framework. The analysis is based on the weakly compressible smoothed particle hydrodynamics formalism. The behavior of the energy terms is studied in standing wave problems by changing the viscosity and the wave amplitude. Finally, an analysis of a complex shallow water breaking wave case is provided. It is shown that in presence of intense breaking phenomena the two energy components are always comparable, whereas generally the free surface component is dominant on the viscous dissipation of gravity waves. PMID:26651775

  12. Local mesh refinement for incompressible fluid flow with free surfaces

    SciTech Connect

    Terasaka, H.; Kajiwara, H.; Ogura, K.

    1995-09-01

    A new local mesh refinement (LMR) technique has been developed and applied to incompressible fluid flows with free surface boundaries. The LMR method embeds patches of fine grid in arbitrary regions of interest. Hence, more accurate solutions can be obtained with a lower number of computational cells. This method is very suitable for the simulation of free surface movements because free surface flow problems generally require a finer computational grid to obtain adequate results. By using this technique, one can place finer grids only near the surfaces, and therefore greatly reduce the total number of cells and computational costs. This paper introduces LMR3D, a three-dimensional incompressible flow analysis code. Numerical examples calculated with the code demonstrate well the advantages of the LMR method.

  13. Numerical study of free surface flow around large obstacles

    NASA Astrophysics Data System (ADS)

    Zhang, Yanming

    In this thesis a numerical model was developed to study three-dimensional turbulent flows around large obstacles in an open channel. With this numerical model, a series of numerical tests was carried out, and the properties of turbulent flows around a single obstacle or a cluster of obstacles were investigated. The origin of this study was to study the flow properties around fish habitat structures. Actually, the numerical model can be applied to the study of general turbulent flows under free surfaces. In the numerical model the three-dimensional Reynolds-averaged Navier-Stokes equations in conjunction with k-epsilon turbulence model were solved in a free surface fitted coordinate system. First, different forms of governing equations for turbulent flow were investigated, and a concise form of fully transformed governing equations in a general curvilinear coordinate system was derived. In the numerical solution the FAVOR (Fractional Area/Volume Obstacle Representation) technique was extended into the free surface fitted coordinate system. With this feature the problem of complex turbulent flow with a free surface and general shaped obstacles could be solved efficiently. To locate the free surface, a method based on integrating the momentum equation in the vertical direction was developed. After study and tests of several popular difference schemes, a QUICK scheme with UMIST limiter was adopted in this numerical model. Several test cases were presented to demonstrate the present numerical model. The first test case was to simulate a submerged hydraulic jump. The calculated velocity, free surface profile and turbulence properties of the flow showed a close match with the experimental data. The second test was a submerged hydraulic jump with a baffle sill. The comparison between numerical and experimental data indicated that the current numerical model could catch the general flow structures of the submerged hydraulic jumps. The last two test cases were flows around a

  14. The surface layer for free-surface turbulent flows

    NASA Astrophysics Data System (ADS)

    Shen, Lian; Zhang, Xiang; Yue, Dick K. P.; Triantafyllou, George S.

    1999-05-01

    Direct numerical simulation (DNS) is used to examine low Froude number free-surface turbulence (FST) over a two-dimensional mean shear flow. The Navier Stokes equations are solved using a finite-difference scheme with a grid resolution of 1283. Twenty separate simulations are conducted to calculate the statistics of the flow. Based on the velocity deficit and the vertical extent of the shear of the mean flow, the Reynolds number is 1000 and the Froude number is 0.7. We identify conceptually and numerically the surface layer, which is a thin region adjacent to the free surface characterized by fast variations of the horizontal vorticity components. This surface layer is caused by the dynamic zero-stress boundary conditions at the free surface and lies inside a thicker blockage (or ‘source’) layer, which is due to the kinematic boundary condition at the free surface. The importance of the outer blockage layer is manifested mainly in the redistribution of the turbulence intensity, i.e. in the increase of the horizontal velocity fluctuations at the expense of the vertical velocity fluctuation. A prominent feature of FST is vortex connections to the free surface which occur inside the surface layer. It is found that as hairpin-shaped vortex structures approach the free surface, their ‘head’ part is dissipated quickly in the surface layer, while the two ‘legs’ connect almost perpendicularly to the free surface. Analysis of the evolution of surface-normal vorticity based on vortex surface-inclination angle shows that both dissipation and stretching decrease dramatically after connection. As a result, vortex structures connected to the free surface are persistent and decay slowly relative to non-connected vorticities. The effects of surface and blockage layers on the turbulence statistics of length scales, Reynolds-stress balance, and enstrophy dynamics are examined, which elucidate clearly the different turbulence mechanisms operating in the respective near

  15. Free surface and flow problem for a viscous liquid

    SciTech Connect

    Zaytsev, M. L. Akkerman, V. B.

    2011-10-15

    An exact closed system of equations is proposed for describing the shape of the free surface of a viscous steady-state liquid in the 2D case in terms of the surface itself. A method that lowers the dimensionality in the Navier-Stokes equation is demonstrated, and its application in problems of steady-state flow past solids is considered.

  16. Wetting and free surface flow modeling for potting and encapsulation.

    SciTech Connect

    Brooks, Carlton, F.; Brooks, Michael J. (Los Alamos National Laboratory, Los Alamos, NM); Graham, Alan Lyman; Noble, David F. ); Notz, Patrick K.; Hopkins, Matthew Morgan; Castaneda, Jaime N.; Mahoney, Leo James; Baer, Thomas A.; Berchtold, Kathryn (Los Alamos National Laboratory, Los Alamos, NM); Adolf, Douglas Brian; Wilkes, Edward Dean; Rao, Rekha Ranjana; Givler, Richard C.; Sun, Amy Cha-Tien; Cote, Raymond O.; Mondy, Lisa Ann; Grillet, Anne Mary; Kraynik, Andrew Michael

    2007-06-01

    As part of an effort to reduce costs and improve quality control in encapsulation and potting processes the Technology Initiative Project ''Defect Free Manufacturing and Assembly'' has completed a computational modeling study of flows representative of those seen in these processes. Flow solutions are obtained using a coupled, finite-element-based, numerical method based on the GOMA/ARIA suite of Sandia flow solvers. The evolution of the free surface is solved with an advanced level set algorithm. This approach incorporates novel methods for representing surface tension and wetting forces that affect the evolution of the free surface. In addition, two commercially available codes, ProCAST and MOLDFLOW, are also used on geometries representing encapsulation processes at the Kansas City Plant. Visual observations of the flow in several geometries are recorded in the laboratory and compared to the models. Wetting properties for the materials in these experiments are measured using a unique flowthrough goniometer.

  17. Unbounded wall flow with free surface waves and horizontal shear

    NASA Astrophysics Data System (ADS)

    Lapham, Gary; McHugh, John

    2015-11-01

    Free surface waves in the presence of a non-uniform shear flow are treated. The shear flow of interest varies with both the transverse and vertical coordinates, U (y , z) . Initial results treat a mean flow varying only with the transverse, U (y) . The domain is bounded on one side by a flat rigid vertical wall and is unbounded on the other side. The mean flows considered here are nonzero near the vertical wall and approach zero far from the wall, e.g. U =e-γy . The flowfield is treated as inviscid but rotational. Linear solutions are obtained using a nonuniform coordinate transformation that converts the free surface boundary condition into a modified Bessel equation. Velocity components are expanded in modified Bessel functions of the first kind of purely imaginary order. The dispersion relation for steady waves are found with wavespeeds outside the range of U, matching previous results for a flow bounded on both sides. Corresponding eigenvectors show a sequence of wave profiles of increasing complexity near the wall. The wave amplitude approaches zero far from the wall.

  18. Flow past a cylinder near a free surface

    NASA Astrophysics Data System (ADS)

    Delaney, Keegan; Vanella, Marcos; Balaras, Elias; Riaz, Amir

    2013-11-01

    Flow past a cylinder close to a free surface gives rise flow phenomena that are very different from ones in cases where the cylinder is fully submerged. In this study we will report resolved large-eddy simulations, where we examine the effects of various parameters that have been shown to effect the flow phenomena in previous experimental studies. In all computations a Navier-Stokes solver for multiphase incompressible flows with immersed boundaries and Adaptive Mesh Refinement is utilized. It employs level-set techniques to sharply define the interface between different phases. A fractional step method is used to solve the momentum and continuity equations, which results in a variable coefficient Poisson pressure equation. Proper jump conditions are applied to the Poisson pressure equation to accurately capture the jump in pressure that results from surface tension between different phases. Scalability and efficiency were placed at a premium during development of the solver, which has been tested to core counts on the order of 10,000. We will present details on the interactions between the free surface and vortices shed from the cylinder and their impact in the structure of the immediate wake and air entrainment. Supported by ONR N000141110588 monitored by Dr. Ki-Han Kim.

  19. Free-surface flow over a semi-circular obstruction

    NASA Astrophysics Data System (ADS)

    Lowery, Kristen; Liapis, Stergios

    1999-05-01

    The fully non-linear free-surface flow over a semi-circular bottom obstruction was studied numerically in two dimensions using a mixed Eulerian-Lagrangian formulation. The problem was solved in the time domain that allows the prediction of a number of transient phenomena, such as the generation of upstream advancing solitary waves, as well as the simulation of wave breaking. A parametric study was performed for a range of values of the depth-based Froude number up to 2.5 and non-dimensional obstacle heights, up to 0.9. When wave breaking does not occur, three distinct flow regimes were identified: subcritical, transcritical and supercritical. When breaking occurs it may be of any type: spilling, plunging or surging. In addition, for values of the Froude number close to 1, the upstream solitary waves break. A systematic study was undertaken to define the boundaries of each type of breaking and non-breaking pattern and to determine the drag and lift coefficients, free-surface profile characteristics and transient behavior. Copyright

  20. JOSEPHINE: A parallel SPH code for free-surface flows

    NASA Astrophysics Data System (ADS)

    Cherfils, J. M.; Pinon, G.; Rivoalen, E.

    2012-07-01

    JOSEPHINE is a parallel Smoothed Particle Hydrodynamics program, designed to solve unsteady free-surface flows. The adopted numerical scheme is efficient and has been validated on a first case, where a liquid drop is stretched over the time. Boundary conditions can also be modelled, as it is demonstrated in a second case: the collapse of a water column. Results show good agreement with both reference numerical solutions and experiments. The use of parallelism allows significant reduction of the computational time, even more with large number of particles. JOSEPHINE has been written so that any untrained developers can handle it easily and implement new features. Catalogue identifier: AELV_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AELV_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 5139 No. of bytes in distributed program, including test data, etc.: 22 833 Distribution format: tar.gz Programming language: Fortran 90 and OpenMPI Computer: All shared or distributed memory parallel processors, tested on a Xeon W3520, 2.67 GHz. Operating system: Any system with a Fortran 90 compiler and MPI, tested on Debian Linux. Has the code been vectorised or parallelised?: The code has been parallelised but has not been explicitly vectorised. RAM: Dependent upon the number of particles. Classification: 4.12 Nature of problem:JOSEPHINE is designed to solve unsteady incompressible flows with a free-surface and large deformations. Solution method:JOSEPHINE is an implementation of Smoothed Particle Hydrodynamics. SPH is a Lagrangian mesh free particle method, thus, no explicit tracking procedure is required to catch the free surface. Incompressibility is satisfied using a weakly compressible model. Boundary conditions at walls are enforced by means of the ghost particles

  1. Finite element simulation of temperature dependent free surface flows

    NASA Technical Reports Server (NTRS)

    Engelman, M. S.; Sani, R. L.

    1985-01-01

    The method of Engelman and Sani (1984) for a finite-element simulation of incompressible surface flows with a free and/or moving fluid interface, such as encountered in crystal growth and coating and polymer technology, is extended to temperature-dependent flows, including the effect of temperature-dependent surface tension. The basic algorithm of Saito and Scriven (1981) and Ruschak (1980) has been generalized and implemented in a robust and versatile finite-element code that can be employed with relative ease for the simulation of free-surface problems in complex geometries. As a result, the costly dependence on the Newton-Raphson algorithm has been eliminated by replacing it with a quasi-Newton iterative method, which nearly retains the superior convergence properties of the Newton-Raphson method.

  2. A kinematic conservation law in free surface flow

    NASA Astrophysics Data System (ADS)

    Gavrilyuk, Sergey; Kalisch, Henrik; Khorsand, Zahra

    2015-06-01

    The Green-Naghdi system is used to model highly nonlinear weakly dispersive waves propagating at the surface of a shallow layer of a perfect fluid. The system has three associated conservation laws which describe the conservation of mass, momentum, and energy due to the surface wave motion. In addition, the system features a fourth conservation law which is the main focus of this note. It will be shown how this fourth conservation law can be interpreted in terms of a concrete kinematic quantity connected to the evolution of the tangent velocity at the free surface. The equation for the tangent velocity is first derived for the full Euler equations in both two and three dimensional flows, and in both cases, it gives rise to an approximate balance law in the Green-Naghdi theory which turns out to be identical to the fourth conservation law for this system. It is also shown that the conservation equation for the tangent velocity at the free surface appears as an endpoint case of a more general conservation equation for tangent velocities along material surfaces in the body of the fluid.

  3. Aging and free surface flow of a thixotropic fluid

    NASA Astrophysics Data System (ADS)

    Huynh, H. T.; Roussel, N.; Coussot, P.

    2005-03-01

    Free surface flows of thixotropic fluids such as paints, self-compacting concrete, or natural mudflows are of noticeable practical interest. Here we study the basic characteristics of the uniform flow of a layer of thixotropic fluid under gravity. A theoretical approach relying on a simple thixotropy constitutive equation shows that after some time at rest over a small slope angle the fluid layer should start to flow rather abruptly beyond a new, larger, critical slope angle. The theory also predicts that the critical time at which the layer velocity should significantly increase is proportional to the duration of the preliminary rest and tends to infinity when the new slope approaches the critical slope. Experiments carried out with different suspensions show that the qualitative trends of the flows are in very good agreement with the theoretical predictions, except that the critical time for flow start appears to be proportional to a power 0.6 of the time of rest whereas the theory predicts a linear dependence. We show that this indicates a restructuration process at rest differing from the restructuration process under flow.

  4. Energy flow and energy dissipation in a free surface.

    NASA Astrophysics Data System (ADS)

    Goldburg, Walter; Cressman, John

    2005-11-01

    Turbulent flows on a free surface are strongly compressible [1] and do not conserve energy in the absence of viscosity as bulk fluids do. Despite violation of assumptions essential to Kolmogorov's theory of 1941 (K41) [2, 3], surface flows show strong agreement with Kolmogorov scaling, though intermittency is larger there. Steady state turbulence is generated in a tank of water, and the spatially averaged energy flux is measured from the four-fifth's law at each instant of time. Likewise, the energy dissipation rate as measured from velocity gradients is also a random variable in this experiment. The energy flux - dissipation rate cross-correlation is measured to be correlated in incompressible bulk flows, but strongly anti-correlated on the surface. We argue that the reason for this discrepancy between surface and bulk flows is due to compressible effects present on the surface. [1] J. R. Cressman, J. Davoudi, W. I. Goldburg, and J. Schumacher, New Journal of Physics, 6, 53, 2004. [2] U. Frisch. Turbulence: The legacy of A. N. Kolmogorov, Cambridge University Press, Cambridge, 1995. [3] A. N. Kolmogorov, Doklady Akad. Nauk SSSR, 32, 16, 1941.

  5. Rotating polygon instability of a swirling free surface flow.

    PubMed

    Tophøj, L; Mougel, J; Bohr, T; Fabre, D

    2013-05-10

    We explain the rotating polygon instability on a swirling fluid surface [G. H. Vatistas, J. Fluid Mech. 217, 241 (1990) and Jansson et al., Phys. Rev. Lett. 96, 174502 (2006)] in terms of resonant interactions between gravity waves on the outer part of the surface and centrifugal waves on the inner part. Our model is based on potential flow theory, linearized around a potential vortex flow with a free surface for which we show that unstable resonant states appear. Limiting our attention to the lowest order mode of each type of wave and their interaction, we obtain an analytically soluble model, which, together with estimates of the circulation based on angular momentum balance, reproduces the main features of the experimental phase diagram. The generality of our arguments implies that the instability should not be limited to flows with a rotating bottom (implying singular behavior near the corners), and indeed we show that we can obtain the polygons transiently by violently stirring liquid nitrogen in a hot container. PMID:23705710

  6. Velocity measurements on highly turbulent free surface flow using ADV

    NASA Astrophysics Data System (ADS)

    Cea, L.; Puertas, J.; Pena, L.

    2007-03-01

    The 3D instantaneous velocity recorded with an acoustic Doppler velocimeter (ADV) in a highly turbulent free surface flow is analysed using several filters in order to eliminate the corrupted data from the sample. The filters used include the minimum/maximum threshold, the acceleration threshold, and the phase-space threshold. Following some ideas of the phase-space filter, a new method based on the 3D velocity cross-correlation is proposed and tested. A way of computing the constants of the acceleration threshold method is proposed, so no parameters need to be fixed by the user, which makes the filtering process simpler, more objective and more efficient. All the samples analysed are highly turbulent. Nevertheless, the turbulence intensity and the air entrainment vary widely in the flow under study, which produces data records of different quality depending on the measurement point. The performance of the filtering methods when applied to samples of different quality, and the effects of the filtering process in the mean velocity, turbulent kinetic energy and frequency spectra are discussed.

  7. On the flow structure of cloud cavitating flow around an axisymmetric body near the free surface

    NASA Astrophysics Data System (ADS)

    Wang, Yiwei; Wu, Xiaocui; Huang, Chenguang; Yu, XianXian

    2015-12-01

    The influence of the free surface on the cavitating flow is an important issue involved in the design of high speed surface vehicles. In the present paper, unsteady cavitating turbulent flow around an axisymmetric body near the free surface was investigated by both launching experiment and LES simulation. The vortex motion induced by cavity shedding under the effect of the free surface is emphatically analyzed by comparing with the submerged condition. The vortex shedding process around the projectile is not synchronized, while the asymmetric characteristic in collapse process is more remarkable, with the generation of multiple vortex ring structures.

  8. Measurement of the interaction between the flow and the free surface of a liquid

    SciTech Connect

    Okamoto, Koji; Schmidl, W.D.; Philip, O.G.

    1995-09-01

    The interaction between the flow and free surface was evaluated measuring the velocity distribution and surface movement simultaneously. The test section was a rectangular tank having a free surface. A rectangular nozzle was set near the free surface, causing the wavy free surface condition. The flow under the free surface was visualized by a laser light sheet and small tracer particles. With image processing techniques, the movement of the free surface and the movement of the particles were simultaneously measured from the recorded images, resulting in the velocity distributions and surface locations. Then, the interactions between the flow and free surface were evaluated using the form of turbulent energy and surface-related turbulent values. By increasing the turbulent energy near the free surface, the fluctuations of the free surface height and the inclination of the free surface were increased. The higher fluctuation of horizontal velocity was related to the higher surface position and negative inclination. The image processing technique is found to be very useful to evaluate the interaction between free surface and flow.

  9. Free surface flow simulation with application to bluff body flow control

    NASA Astrophysics Data System (ADS)

    Kocabiyik, S.; Bozkaya, C.

    2015-03-01

    To better understand the interaction of a free surface wave motion with moving bluff bodies, a two-dimensional numerical study of the forced streamwise oscillation of a circular cylinder beneath a free surface is conducted based on a two-fluid model. Computations are carried out at a Reynolds number of R = 200, a fixed displacement amplitude, A = 0.13 and the forcing frequency-to-natural shedding frequency ratios, f/ f 0 = 1.5,2.5,3.5. Finite volume discretization of the special integral form of two-dimensional continuity and unsteady Navier-Stokes equations (when a solid body is present) are performed on a fixed Cartesian grid. Improved volume-of-fluid method is used to discretize the free surface. The laminar asymmetric flow regimes in the near wake region and the fluid forces are analyzed at a fixed Froude number of Fr = 0.4 and for submergence depths at h = 0.25,0.5,0.75. A comparison of the present results with the case in the absence of a free surface is also included to illustrate the effects of inclusion of a free surface. The code validation in special cases shows good comparisons with previous numerical and experimental results. Flow regime analyses include free surface physics-based analysis, and results confirm findings of a recent work of Brøns et al. [25].

  10. Method of driving liquid flow at or near the free surface using magnetic microparticles

    DOEpatents

    Snezhko, Oleksiy; Aronson, Igor; Kwok, Wai-Kwong; Belkin, Maxim V.

    2011-10-11

    The present invention provides a method of driving liquid flow at or near a free surface using self-assembled structures composed of magnetic particles subjected to an external AC magnetic field. A plurality of magnetic particles are supported at or near a free surface of liquid by surface tension or buoyancy force. An AC magnetic field traverses the free surface and dipole-dipole interaction between particles produces in self-assembled snake structures which oscillate at the frequency of the traverse AC magnetic field. The snake structures independently move across the free surface and may merge with other snake structures or break up and coalesce into additional snake structures experiencing independent movement across the liquid surface. During this process, the snake structures produce asymmetric flow vortices across substantially the entirety of the free surface, effectuating liquid flow across the free surface.

  11. Selected flows with free surfaces: Streams and drops

    NASA Astrophysics Data System (ADS)

    Kowalewski, Tomasz A.

    1995-03-01

    The basic purpose of the research described in this article was to develop a non contact method for diagnosing the physical parameters of the free surface of a liquid using drop oscillation analysis. In particular, the purpose is to measure the temperature of an evaporating surface. The realization of this goal has led to the development of new experimental techniques which make it possible to record fast processes using video and digital imaging equipment. Experimental studies of the process of the formation of drops as a result of the controlled breakup of a stream revealed the existence of an additional phase in the process based on the formation of microstreams and microsatellites with micrometer-like dimensions. A comparison of measurement results with Eggers' asymptotic model (23) confirmed the model's basic assumption of the local nature of the final phase in the disintegration of the stream, which at the same time points to the existence of a number of discrepancies which provide evidence of the limitations of this approximation. The next part of the article presents the results of observations of the instability of streams of liquid caused by its evaporation. In an attempt to analyze the mechanisms which initiate the turbulence of the evaporating surface, the author focused on surface tension gradients as an essential factor in the destabilization of small-diameter streams. The author also described the occurrence of a number of new phenomena in the destabilization of a stream, including the separation of surface fragments, their stabilization by the flow of vapor, and a quasistable change in the trajectory of the stream. The author also developed an experimental method which makes it possible to detect and produce a precise description of the deformation of drops. Measurements of the oscillations of small drops in the air led to the development of a complete non-linear model of the oscillations of a viscous drop and made it possible to verify simplified

  12. Computation of effective free surfaces in two phase flows

    NASA Astrophysics Data System (ADS)

    Yapalparvi, R.; Protas, B.

    2012-08-01

    In this investigation we revisit the concept of "effective free surfaces" arising in the solution of the time-averaged fluid dynamics equations in the presence of free boundaries. This work is motivated by applications of the optimization and optimal control theory to problems involving free surfaces, where the time-dependent formulations lead to many technical difficulties which are, however, alleviated when steady governing equations are used instead. By introducing a number of precisely stated assumptions we develop and validate an approach in which the interface between the different phases, understood in the time-averaged sense, is sharp. In the proposed formulation, the terms representing the fluctuations of the free boundaries and of the hydrodynamic quantities appear as boundary conditions on the effective surface and require suitable closure models. As a simple model problem we consider impingement of free-falling droplets onto a fluid in a pool with a free surface, and a simple algebraic closure model is proposed for this system. The resulting averaged equations are of the free-boundary type and an efficient computational approach based on shape optimization formulation is developed for their solution. The computed effective surfaces exhibit consistent dependence on the problem parameters and compare favorably with the results obtained when the data from the actual time-dependent problem are used in lieu of the closure model.

  13. An experimental study of free surface deformation in oscillatory thermocapillary flow

    NASA Technical Reports Server (NTRS)

    Lin, Jianlian; Kamotani, Yasuhiro; Ostrach, Simon

    1995-01-01

    Free surface deformation of a test fluid induced by steady and oscillatory thermocapillary flow in a small cylindrical container (diameter = 4.8 mm) is studied experimentally. The fluid (2 Cs oil) is heated by a cylindrical wire (diameter = 0.48 mm) placed along the centerline of the cylinder. The relative displacement and oscillation frequency of free surface are measured in a radial cross-section for various applied temperature differences. It is found that the amplitude of the free surface height oscillations is large near the heater and the cold wall and relatively small in the middle part. The frequency of the free surface oscillations is same as the frequency of the temperature oscillations. Based on these data, the free surface motion during oscillations is delineated.

  14. Improving the Dupuit-Forchheimer Approximation for Free Surface Flow in an Unconfined Aquifer

    NASA Astrophysics Data System (ADS)

    Knight, J. H.

    2003-12-01

    The classical Dupuit-Forchheimer (DF) approximation for groundwater free surface flow in an unconfined aquifer assumes that the vertical component of the seepage velocity is zero. This assumption is expected to be least accurate when there is non-zero accretion at the free surface. The DF approximation leads to a nonlinear diffusion equation satisfied by the height of the free surface. The general principles of integral methods used by Yves Parlange are to assume some simple approximate shape for some unknown function, and then to choose the parameters of this function to satisfy some known integral relation of the flow system. The DF approximation is improved by assuming that the vertical velocity component is zero at the impermeable horizontal base, and increases linearly to its unknown value at the free surface. The well known Guirinsky potential which depends only on the free surface height corresponds to the DF assumptions. Youngs used an integral relation to define a new potential which depends on the free surface height and also on the vertical velocity component, and which for steady flow satisfies a Poisson equation in the horizontal coordinates. We use the assumption of linear variation of vertical velocity to calculate an approximation to the Youngs potential. In some simple flow systems such as the classical dam problem this leads to a simple differential equation for the free surface height, which can be solved numerically. ln some cases simple explicit approximations can be found for quantities of interest, such as the maximum free surface height between drainage ditches.

  15. Free-surface flow around an appended hull

    NASA Astrophysics Data System (ADS)

    Lungu, A.; Pacuraru, F.

    2010-08-01

    The prediction of the total drag experienced by an advancing ship is a complicated problem which requires a thorough understanding of the hydrodynamic forces acting on the hull, the physical processes from which these forces arise as well as their mutual interaction. A general numerical method to predict the hydrodynamic performance of a twin-propeller combatant ship is presented in the paper, which describes the solution of a RANS solver coupled with a body force method as an attempt in investigating the flow features around the ship hull equipped with rotating propellers and rudders. A special focus is made on the propeller non-symmetrical inflow field, aimed at obtaining the necessary data for the propulsive performances evaluation as well as for the propeller final design. The reported work allows not only the performance evaluation for the overall performances of a hull, but also leads to the development, implementation and validation of new concepts in modeling the turbulent vortical flows, with direct connection to the ship propulsion problem.

  16. Nonlinear dynamics and breakup of free-surface flows

    SciTech Connect

    Eggers, J.

    1997-07-01

    Surface-tension-driven flows and, in particular, their tendency to decay spontaneously into drops have long fascinated naturalists, the earliest systematic experiments dating back to the beginning of the 19th century. Linear stability theory governs the onset of breakup and was developed by Rayleigh, Plateau, and Maxwell. However, only recently has attention turned to the nonlinear behavior in the vicinity of the singular point where a drop separates. The increased attention is due to a number of recent and increasingly refined experiments, as well as to a host of technological applications, ranging from printing to mixing and fiber spinning. The description of drop separation becomes possible because jet motion turns out to be effectively governed by one-dimensional equations, which still contain most of the richness of the original dynamics. In addition, an attraction for physicists lies in the fact that the separation singularity is governed by universal scaling laws, which constitute an asymptotic solution of the Navier-Stokes equation before and after breakup. The Navier-Stokes equation is thus continued uniquely through the singularity. At high viscosities, a series of noise-driven instabilities has been observed, which are a nested superposition of singularities of the same universal form. At low viscosities, there is rich scaling behavior in addition to aesthetically pleasing breakup patterns driven by capillary waves. The author reviews the theoretical development of this field alongside recent experimental work, and outlines unsolved problems. {copyright} {ital 1997} {ital The American Physical Society}

  17. Effect of free surface on near-wake flow of elliptic cylinders with different aspect ratios

    NASA Astrophysics Data System (ADS)

    Lee, Sang Joon; Daichin, -

    2003-04-01

    The flow fields behind elliptic cylinders with different aspect ratios adjacent to a free surface were investigated experimentally in a circulating water channel. The elliptic cylinders tested in this study have same cross section area. For each elliptic cylinder, the experiments were carried out under different conditions by varying the submergence depth of the cylinder beneath the free surface. The flow fields were measured using a single-frame double-exposure PIV system. For each experimental condition, 350 instantaneous velocity fields were captured and ensemble-averaged to obtain the mean flow field information and spatial distribution of turbulent statistics. The near-wakes can be basically classified into three typical patterns, which are formation of Coanda effect, generation of substantial jet-like flow, and attachment of jet flow to the free surface. The general flow structures behind the elliptic cylinder are similar to previous results for a circular submerged near to a free surface. However, the wake width and the angle of downward deflection of the shear layer developed from the lower surface of the elliptic cylinder are smaller than those for the circular cylinder. These trends are enhance with increasing of the cylinder aspect ratios.

  18. Free-surface potential flow of an ideal fluid due to a singular sink

    NASA Astrophysics Data System (ADS)

    Mestnikova, A. A.; Starovoitov, V. N.

    2016-06-01

    A two-dimensional problem of a potential free-surface flow of an ideal incompressible fluid caused by a singular sink is considered. The sink is placed at the horizontal bottom of the channel. By employing a conformal map, the problem is equivalently rewritten in the unit circle. After that, it is investigated by the Levi — Civita technique with the extraction of the singular part of the flow that corresponds to the sink. We derive a Nekrasov type equation that describes exactly the form of the free boundary. This equation is studied at first numerically and then by an exact mathematical technique. It is shown that for the Froude number greater than some particular value, there exists a unique solution of the problem such that the free surface decreases monotonically when moving from the infinity to the sink. At the point over the sink, the free surface has a cusp.

  19. The capturing of free surfaces in incompressible multi-fluid flows

    NASA Astrophysics Data System (ADS)

    Pan, Dartzi; Chang, Chih-Hao

    2000-05-01

    By treating it as a contact discontinuity in the density field, a free surface between two immiscible fluids can be automatically captured by the enforcement of conservation laws. A surface-capturing method of this kind requires no special tracking or fitting treatment for the free surface, thereby offering the advantage of algorithm simplicity over the surface-tracking or the surface-fitting method. A surface-capturing method based on a new multi-fluid incompressible Navier-Stokes formulation is developed. It is applied to a variety of free-surface flows, including the Rayleigh-Taylor instability problem, the ship waves around a Wigley hull and a model bubble-rising problem to demonstrate the validity and versatility of the present method. Copyright

  20. Phase-detection measurements in free-surface turbulent shear flows

    NASA Astrophysics Data System (ADS)

    Chanson, Hubert

    2016-04-01

    High-velocity self-aerated flows are described as ‘white waters’ because of the entrained air bubbles. The air entrainment induces a drastic change in the multiphase flow structure of the water column and this leads to significant bubble-turbulence interactions, turbulence modulation and associated mixing processes impacting on the bulk flow properties. In these high-velocity free-surface turbulent flows, the phase-detection needle probe is a most reliable instrumentation. The signal processing of a phase-detection probe is re-visited herein. It is shown that the processing may be performed on the raw probe signal as well as the thresholded data. The latter yields the time-averaged void fraction, the bubble count rate, the particle chord time distributions and the particle clustering properties within the particulate flow regions. The raw probe signal analysis gives further the auto-correlation time scale and the power spectrum density function. Finally dimensional considerations are developed with a focus on the physical modelling of free-surface flows in hydraulic structures. It is argued that the notion of scale effects must be defined in terms of some specific set of air-water flow properties within well-defined testing conditions, while a number of free-surface flow characteristics are more prone to scale effects than others, even in large-size physical facilities.

  1. Laboratory Study of MHD Effects on Stability of Free-surface Liquid Metal Flow

    NASA Astrophysics Data System (ADS)

    Burin, M. J.; Ji, H.; McMurtry, K.; Peterson, L.; Giannakis, D.; Rosner, R.; Fischer, P.

    2006-10-01

    The dynamics of free-surface MHD shear flows is potentially important to both astrophysics (e.g. in the mixing of dense plasma accreted upon neutron star surfaces) and fusion reactors (e.g. in liquid metal ‘first walls’). To date however few relevant experiments exist. In order to study the fundamental physics of such flows, a small-scale laboratory experiment is being built using a liquid gallium alloy flowing in an open- channel geometry. The flow dimensions are nominally 10cm wide, 1cm deep, and 70cm long under an imposed magnetic field up to 7kG, leading to maximum Hartman number of 2000 and maximum Reynolds number of 4x10^5. Two basic physics issues will ultimately be addressed: (1) How do MHD effects modify the stability of the free surface? For example, is the flow more stable (through the suppression of cross-field motions), or less stable (through the introduction of new boundary layers)? We also investigate whether internal shear layers and imposed electric currents can control the surface stability. (2) How do MHD effects modify free-surface convection driven by a vertical and/or horizontal temperature gradient? We discuss aspects of both of these issues, along with detailed descriptions of the experimental device. Pertinent theoretical stability analyses and initial hydrodynamic results are presented in companion posters. This work is supported by DoE under contract #DE-AC02-76-CH03073.

  2. A particle filter to reconstruct a free-surface flow from a depth camera

    NASA Astrophysics Data System (ADS)

    Combés, Benoit; Heitz, Dominique; Guibert, Anthony; Mémin, Etienne

    2015-10-01

    We investigate the combined use of a kinect depth sensor and of a stochastic data assimilation (DA) method to recover free-surface flows. More specifically, we use a weighted ensemble Kalman filter method to reconstruct the complete state of free-surface flows from a sequence of depth images only. This particle filter accounts for model and observations errors. This DA scheme is enhanced with the use of two observations instead of one classically. We evaluate the developed approach on two numerical test cases: a collapse of a water column as a toy-example and a flow in an suddenly expanding flume as a more realistic flow. The robustness of the method to depth data errors and also to initial and inflow conditions is considered. We illustrate the interest of using two observations instead of one observation into the correction step, especially for unknown inflow boundary conditions. Then, the performance of the Kinect sensor in capturing the temporal sequences of depth observations is investigated. Finally, the efficiency of the algorithm is qualified for a wave in a real rectangular flat bottomed tank. It is shown that for basic initial conditions, the particle filter rapidly and remarkably reconstructs the velocity and height of the free surface flow based on noisy measurements of the elevation alone.

  3. SPH simulation of free surface flow over a sharp-crested weir

    NASA Astrophysics Data System (ADS)

    Ferrari, Angela

    2010-03-01

    In this paper the numerical simulation of a free surface flow over a sharp-crested weir is presented. Since in this case the usual shallow water assumptions are not satisfied, we propose to solve the problem using the full weakly compressible Navier-Stokes equations with the Tait equation of state for water. The numerical method used consists of the new meshless Smooth Particle Hydrodynamics (SPH) formulation proposed by Ferrari et al. (2009) [8], that accurately tracks the free surface profile and provides monotone pressure fields. Thus, the unsteady evolution of the complex moving material interface (free surface) can been properly solved. The simulations involving about half a million of fluid particles have been run in parallel on two of the most powerful High Performance Computing (HPC) facilities in Europe. The validation of the results has been carried out analysing the pressure field and comparing the free surface profiles obtained with the SPH scheme with experimental measurements available in literature [18]. A very good quantitative agreement has been obtained.

  4. Coupling of Smoothed Particle Hydrodynamics with Finite Volume method for free-surface flows

    NASA Astrophysics Data System (ADS)

    Marrone, S.; Di Mascio, A.; Le Touzé, D.

    2016-04-01

    A new algorithm for the solution of free surface flows with large front deformation and fragmentation is presented. The algorithm is obtained by coupling a classical Finite Volume (FV) approach, that discretizes the Navier-Stokes equations on a block structured Eulerian grid, with an approach based on the Smoothed Particle Hydrodynamics (SPH) method, implemented in a Lagrangian framework. The coupling procedure is formulated in such a way that each solver is applied in the region where its intrinsic characteristics can be exploited in the most efficient and accurate way: the FV solver is used to resolve the bulk flow and the wall regions, whereas the SPH solver is implemented in the free surface region to capture details of the front evolution. The reported results clearly prove that the combined use of the two solvers is convenient from the point of view of both accuracy and computing time.

  5. Algorithm for the simulation of transient viscoelastic flows with free surfaces

    SciTech Connect

    Keunings, R.

    1986-01-01

    We propose a numerical procedure for solving a class of transient viscoelastic flows with free surfaces. It is based on a Galerkin/Finite Element technique on deforming elements combined with a predictor-corrector scheme. The method is applied to the analysis of jet breakup caused by capillary forces. Non-linear effects known to experimentalists are predicted and a detailed comparison with asymptotic results is carried out.

  6. Algorithm for the simulation of transient viscoelastic flows with free surfaces

    SciTech Connect

    Keunings, R.

    1984-10-01

    We propose a numerical procedure for solving a class of transient viscoelastic flows with free surfaces. It is based on a Galerkin/Finite Element technique on deforming elements combined with a predictor-corrector scheme. The method is applied to the analysis of jet breakup caused by capillary forces. Non-linear effects known to experimentalists are predicted and a detailed comparison with asymptotic results is carried out.

  7. An improved parallel SPH approach to solve 3D transient generalized Newtonian free surface flows

    NASA Astrophysics Data System (ADS)

    Ren, Jinlian; Jiang, Tao; Lu, Weigang; Li, Gang

    2016-08-01

    In this paper, a corrected parallel smoothed particle hydrodynamics (C-SPH) method is proposed to simulate the 3D generalized Newtonian free surface flows with low Reynolds number, especially the 3D viscous jets buckling problems are investigated. The proposed C-SPH method is achieved by coupling an improved SPH method based on the incompressible condition with the traditional SPH (TSPH), that is, the improved SPH with diffusive term and first-order Kernel gradient correction scheme is used in the interior of the fluid domain, and the TSPH is used near the free surface. Thus the C-SPH method possesses the advantages of two methods. Meanwhile, an effective and convenient boundary treatment is presented to deal with 3D multiple-boundary problem, and the MPI parallelization technique with a dynamic cells neighbor particle searching method is considered to improve the computational efficiency. The validity and the merits of the C-SPH are first verified by solving several benchmarks and compared with other results. Then the viscous jet folding/coiling based on the Cross model is simulated by the C-SPH method and compared with other experimental or numerical results. Specially, the influences of macroscopic parameters on the flow are discussed. All the numerical results agree well with available data, and show that the C-SPH method has higher accuracy and better stability for solving 3D moving free surface flows over other particle methods.

  8. Simulation of gravity driven free-surface flow in fractured geological media

    SciTech Connect

    Kordilla, Jannes; Geyer, Tobias; Tartakovsky, Alexandre M.

    2011-08-25

    Abstract—Simulation of unsaturated free-surface flow in fractured geological media represents a challenge due to the highly heterogeneous flow field induced by extensive faults, joints and fissures. Free-surface flow in unsaturated media leads to highly intermittent flow regimes and flow velocities well above those assumed for the bulk volume. However, common modeling approaches relying on volume-averaged effective equations fail to capture this flow feature. In this work we present micro-scale flow simulations using a three-dimensional multiphase SPH code. Pairwise fluid-fluid and solid-fluid interaction forces are used to simulate a wide range of wetting conditions encountered on rock surfaces. It is shown that static contact angles for sessiles droplets are independent of the model discretization, i.e. the total amount of particles. Thus, computation times can be reduced without sacrificing qualitative or quantitative information. Furthermore we show that our model is in accordance with general scaling laws for droplet flow.

  9. Free surface flow through rock-fill dams analyzed by FEM with level set approach

    NASA Astrophysics Data System (ADS)

    Sharif, N. H.; Wiberg, N.-E.; Levenstam, M.

    A stabilized-finite element formulation is coupled with a level set technique for computations of incompressible non-linear flow with interfaces between two immiscible fluids. An interface capturing formulation (ICF) for non-linear, free surface, seepage flow in rock-fill dams is proposed. The formulation is derived for two- and three-dimensional flow within a fixed mesh domain. The resulting formulation is general and applicable for various steady and transient two-phase flow problems. FE-refinement is processed for the entire fixed mesh domains. A general solver is also reviewed for large and non-symmetric non-positive definite linear system of equations with the GMRES-update technique based on a Newton-iterative method. The computational procedure has been implemented in MATLAB. A comparison is performed between the 2-D computed test problem for coarse and refined meshes together with some proposed analytical solutions for nonlinear seepage flow with free surface in rock-fill dams. An expansion of the 2-D program code to a 3-D one for a rectangular rock-fill dam is also developed and simulated in MATLAB. The performance of the computations in 3-D is very promising and its opening the future for possible industrial applications using the same simple technique. Computations for a simple 3-D seepage flow problem with free surface in rock-fill dam are included in present paper. A general mesh generator and solver for large scale and complex 3-D flow problems in a real embankment dam is also under construction in C++.

  10. Three-dimensional low Reynolds number flows with a free surface

    NASA Technical Reports Server (NTRS)

    Degani, D.; Gutfinger, C.

    1977-01-01

    The two-dimensional leveling problem (Degani, Gutfinger, 1976) is extended to three dimensions in the case where the flow Re number is very low and attention is paid to the free surface boundary condition with surface tension effects included. The no-slip boundary condition on the wall is observed. The numerical solution falls back on the Marker and Cell (MAC) method (Harlow and Welch, 1965) with the computation region divided into a finite number of stationary rectangular cells (or boxes in the 3-D case) and fluid flow traverses the cells (or boxes).

  11. Magnetohydrodynamics and heat transfer in a free-surface, flowing liquid metal experiment

    NASA Astrophysics Data System (ADS)

    Rhoads, John Rayburn

    This thesis examines magnetohydrodynamic (MHD) effects and heat transfer in free-surface, liquid metal flow. The interaction of the flow with the applied magnetic field introduces an anisotropy to the fluid motion, resulting in starkly different behavior depending on the orientation and strength of the applied magnetic field. The transition from a hydrodynamic state to an MHD state was experimentally found to be characterized by the interaction parameter, N = sigma L B20/rho v0 , crossing above 0.5. The experiment consisted of a channel 1 m in length, up to 16 cm in width and 1 to 2.5 cm in depth situated within an electromagnet capable of producing a uniform magnetic field up to 2.7 kG. The fluid velocity was measured with an array of 25 potential probes that resolved the spanwise velocity profile, while waves on the surface of the metal were monitored via a diagnostic that tracked the motion of a laser beam reflected off of the free surface. Lastly, the temperature response of the fluid was recorded with an array of 32 thermocouples embedded in the bottom of the channel and a mid-wavelength infrared camera used to image the free surface. Three distinct sets of experiments were performed to investigate the effects of the applied magnetic field on the dynamics within the flow, studying: 1) changes to vortices in the wake of a cylinder, 2) behavior of surface fluctuations due to the turbulent flow, and 3) vertical heat transfer resulting from heat deposition on the free surface. The first set of experiments examined the wake of a cylinder inserted into the flow with its axis parallel to the magnetic field. Measurements with the potential probes indicated that vortices in the wake became laminarized as the field was increased due to the alignment of the injected vorticity with the applied field. The second set of experiments showed that surface fluctuations were suppressed at high magnetic fields, but the precise nature of the damping depended on the orientation of

  12. Nanometer-scale free surface flow of molten polyethylene from a heated atomic force microscope tip

    NASA Astrophysics Data System (ADS)

    Ewoldt, Randy; Felts, Jonathan; Somnath, Suhas; King, William

    2012-11-01

    We experimentally investigate nanometer-scale free surface flow of molten polyethylene from a heated atomic force microscope (AFM) cantilever, a nanofabrication process known as thermal dip-pen nanolithography (tDPN). Fluid is deposited from the AFM tip onto non-porous substrates whether the tip is moving or fixed. We find that polymer flow depends on surface capillary forces and not on shear between tip and substrate. The polymer mass flow rate is sensitive to the temperature-dependent polymer viscosity. Additionally, the flow rate increases when a temperature gradient exists between the tip and substrate. We hypothesize that the polymer flow is governed by thermal Marangoni forces and non-equilibrium wetting dynamics caused by a solidification front within the feature.

  13. Note: Proton irradiation at kilowatt-power and neutron production from a free-surface liquid-lithium target

    NASA Astrophysics Data System (ADS)

    Halfon, S.; Arenshtam, A.; Kijel, D.; Paul, M.; Weissman, L.; Aviv, O.; Berkovits, D.; Dudovitch, O.; Eisen, Y.; Eliyahu, I.; Feinberg, G.; Haquin, G.; Hazenshprung, N.; Kreisel, A.; Mardor, I.; Shimel, G.; Shor, A.; Silverman, I.; Tessler, M.; Yungrais, Z.

    2014-05-01

    The free-surface Liquid-Lithium Target, recently developed at Soreq Applied Research Accelerator Facility (SARAF), was successfully used with a 1.9 MeV, 1.2 mA (2.3 kW) continuous-wave proton beam. Neutrons (˜2 × 1010 n/s having a peak energy of ˜27 keV) from the 7Li(p,n)7Be reaction were detected with a fission-chamber detector and by gold activation targets positioned in the forward direction. The setup is being used for nuclear astrophysics experiments to study neutron-induced reactions at stellar energies and to demonstrate the feasibility of accelerator-based boron neutron capture therapy.

  14. Note: Proton irradiation at kilowatt-power and neutron production from a free-surface liquid-lithium target

    SciTech Connect

    Halfon, S.; Feinberg, G.; Arenshtam, A.; Kijel, D.; Weissman, L.; Aviv, O.; Berkovits, D.; Dudovitch, O.; Eisen, Y.; Eliyahu, I.; Haquin, G.; Hazenshprung, N.; Kreisel, A.; Mardor, I.; Shimel, G.; Shor, A.; Silverman, I.; Yungrais, Z.; Paul, M. Tessler, M.

    2014-05-15

    The free-surface Liquid-Lithium Target, recently developed at Soreq Applied Research Accelerator Facility (SARAF), was successfully used with a 1.9 MeV, 1.2 mA (2.3 kW) continuous-wave proton beam. Neutrons (∼2 × 10{sup 10} n/s having a peak energy of ∼27 keV) from the {sup 7}Li(p,n){sup 7}Be reaction were detected with a fission-chamber detector and by gold activation targets positioned in the forward direction. The setup is being used for nuclear astrophysics experiments to study neutron-induced reactions at stellar energies and to demonstrate the feasibility of accelerator-based boron neutron capture therapy.

  15. Motion of a cylinder adjacent to a free-surface: flow patterns and loading

    NASA Astrophysics Data System (ADS)

    Zhu, Q.; Lin, J.-C.; Unal, M. F.; Rockwell, D.

    The flow structure and loading due to combined translatory and sinusoidal motion of a cylinder adjacent to a free-surface are characterized using a cinema technique of high-image-density particle image velocimetry and simultaneous force measurements. The instantaneous patterns of vorticity and streamline topology are interpreted as a function of degree of submergence beneath the free-surface. The relative magnitudes of the peak vorticity and the circulation of vortices formed from the upper and lower surfaces of the cylinder, as well as vortex formation from the free-surface, are remarkably affected by the nominal submergence. The corresponding streamline topology, interpreted in terms of foci, saddle points, and multiple separation and reattachment points also exhibit substantial changes with submergence. All of these features affect the instantaneous loading of the cylinder. Calculation of instantaneous moments of vorticity and the incremental changes in these moments during the cylinder motion allow identification of those vortices that contribute most substantially to the instantaneous lift and drag. Furthermore, the calculated moments are in general accord with the time integrals of the measured lift and drag acting on the cylinder for sufficiently large submergence.

  16. An improved weakly compressible SPH method for simulating free surface flows of viscous and viscoelastic fluids

    NASA Astrophysics Data System (ADS)

    Xu, Xiaoyang; Deng, Xiao-Long

    2016-04-01

    In this paper, an improved weakly compressible smoothed particle hydrodynamics (SPH) method is proposed to simulate transient free surface flows of viscous and viscoelastic fluids. The improved SPH algorithm includes the implementation of (i) the mixed symmetric correction of kernel gradient to improve the accuracy and stability of traditional SPH method and (ii) the Rusanov flux in the continuity equation for improving the computation of pressure distributions in the dynamics of liquids. To assess the effectiveness of the improved SPH algorithm, a number of numerical examples including the stretching of an initially circular water drop, dam breaking flow against a vertical wall, the impact of viscous and viscoelastic fluid drop with a rigid wall, and the extrudate swell of viscoelastic fluid have been presented and compared with available numerical and experimental data in literature. The convergent behavior of the improved SPH algorithm has also been studied by using different number of particles. All numerical results demonstrate that the improved SPH algorithm proposed here is capable of modeling free surface flows of viscous and viscoelastic fluids accurately and stably, and even more important, also computing an accurate and little oscillatory pressure field.

  17. Efficient Computation of N-S Equation with Free Surface Flow Around an ACV on ShirazUCFD Grid

    NASA Astrophysics Data System (ADS)

    Sheikhalishahi, Seyyed Mehdi; Alizadehrad, Davood; Dastghaibyfard, Gholamhossein; Alishahi, Mohammad Mehdi; Nikseresht, Amir Hossein

    This paper presents the application of a parallel high accuracy simulation code for Incompressible Navier-Stokes solution with free surface flow around an ACV (Air Cushion Vehicle) on ShirazUCFD Grid environment. The parallel finite volume code is developed for incompressible Navier-Stokes solver on general curvilinear coordinates system for modeling free surface flows. A single set of dimensionless equations is derived to handle both liquid and air phases in viscous incompressible free surface flow in general curvilinear coordinates. The volume of fluid (VOF) method with lagrangian propagation in computational domain for modeling the free surface flow is implemented. The parallelization approach uses a domain decomposition method for the subdivision of the numerical grid, the SPMD program model and MPICH-G2 as the message passing environment is used to obtain a portable application.

  18. Time-dependent liquid metal flows with free convection and free surfaces

    SciTech Connect

    McClelland, M.A.

    1990-11-01

    A finite element analysis is given for time-dependent liquid metal flows with free convection and free surfaces. Consideration is given to a two-dimensional shallow trough with vertical walls maintained at different temperatures. The spatial formulation incorporates mixed Lagrangian approximations to the velocity, pressure, temperature, and interface position. The time integration method is performed using the Trapezoid Rule with step-size control. The Galerkin method is employed to reduce the problem to a set of nonlinear algebraic equations which are solved with the Newton-Raphson method. Calculations are performed for conditions relevant to the electron beam vaporization of refractory metals. The Prandtl number is 0.015, and Grashof numbers are in the transition region between laminar and turbulent flow. The results reveal the effects of flow intensity, surface-tension gradients, and mesh and time-step refinement.

  19. Application of the Analogy Between Water Flow with a Free Surface and Two-Dimensional Compressible Gas Flow

    NASA Technical Reports Server (NTRS)

    Orlin, W James; Lindner, Norman J; Butterly, Jack G

    1947-01-01

    The theory of the hydraulic analogy -- that is, the analogy between water flow with a free surface and two-dimensional compressible gas flow -- and the limitations and conditions of the analogy are discussed. A test was run using the hydraulic analogy as applied to the flow about circular cylinders of various diameters at subsonic velocities extending into the supercritical range. The apparatus and techniques used in this application are described and criticized. Reasonably satisfactory agreement of pressure distributions and flow fields existed between water and air flow about corresponding bodies. This agreement indicated the possibility of extending experimental compressibility research by new methods.

  20. Incompressible SPH Model for Simulating Violent Free-Surface Fluid Flows

    NASA Astrophysics Data System (ADS)

    Staroszczyk, Ryszard

    2014-06-01

    In this paper the problem of transient gravitational wave propagation in a viscous incompressible fluid is considered, with a focus on flows with fast-moving free surfaces. The governing equations of the problem are solved by the smoothed particle hydrodynamics method (SPH). In order to impose the incompressibility constraint on the fluid motion, the so-called projection method is applied in which the discrete SPH equations are integrated in time by using a fractional-step technique. Numerical performance of the proposed model has been assessed by comparing its results with experimental data and with results obtained by a standard (weakly compressible) version of the SPH approach. For this purpose, a plane dam-break flow problem is simulated, in order to investigate the formation and propagation of a wave generated by a sudden collapse of a water column initially contained in a rectangular tank, as well as the impact of such a wave on a rigid vertical wall. The results of simulations show the evolution of the free surface of water, the variation of velocity and pressure fields in the fluid, and the time history of pressures exerted by an impacting wave on a wall.

  1. Instabilities in free-surface Hartmann flow at low magnetic Prandtl numbers

    NASA Astrophysics Data System (ADS)

    Giannakis, Dimitrios

    2009-06-01

    Free-surface Hartmann flow is the parallel flow of a viscous, electrically conducting, capillary fluid on a planar surface, subject to gravity and a flow- normal magnetic field. This type of flow arises in a variety of industrial and astrophysical contexts, including liquid-metal walls in fusion devices, heavy- ion accelerator targets, and surface layers of white dwarfs and neutron stars. Typically, the Reynolds number, Re >10 4 , is high, and the background magnetic field is strong ( Ha >100, where the Hartmann number, Ha , measures the square root of the ratio of electromagnetic to viscous forces). On the other hand, the magnetic Prandtl number, Pm (the ratio of viscous to magnetic diffusivity), of laboratory fluids is small (e.g., Pm <10 -4 for liquid metals), as is the case in a number of astrophysical models. When the background magnetic field is zero, free-surface Hartmann flow exhibits the so-called soft and hard instability modes; the former being a surface wave destabilized by viscous stresses acting on the free surface, whereas the latter is a shear mode destabilized by positive Reynolds stress associated with an internal critical layer. We study in detail the influence of the external magnetic field on these two instabilities, working in the regime Pm <10^-4. We also consider flows in the inductionless limit, Pr [arrow right]0, where magnetic field perturbations diffuse infinitely fast, and the sole MHD effect is a Lorentz force arising from currents induced by the perturbed fluid motion within the background magnetic field. We have developed a spectral Galerkin method to solve the coupled Orr- Sommerfeld and induction equations, which, in conjunction with suitable stress conditions at the free surface and continuity conditions for the magnetic field, govern the linear stability of free-surface Hartmann flow. Our scheme's discrete bases for the velocity and magnetic fields consist of linear combinations of Legendre polynomials, chosen according to the

  2. Application of the Analogy Between Water Flow with a Free Surface and Two-dimensional Compressible Gas Flow

    NASA Technical Reports Server (NTRS)

    Orlin, W James; Lindner, Norman J; Bitterly, Jack G

    1947-01-01

    The theory of hydraulic analogy, that is, the analogy between water flow with a free surface and two-dimensional compressible gas flow and the limitations and conditions of the analogy are discussed. A test run was made using the hydraulic analogy as applied to the flow about circular cylinders at various diameters at subsonic velocities extending to the super critical range. The apparatus and techniques used in this application are described and criticized. Reasonably satisfactory agreement of pressure distributions and flow fields existed between water and airflow about corresponding bodies. This agreement indicated the possibility of extending experimental compressibility research by new methods.

  3. Strongly coupled partitioned approach for fluid structure interaction in free surface flows

    NASA Astrophysics Data System (ADS)

    Facci, Andrea Luigi; Ubertini, Stefano

    2016-06-01

    In this paper we describe and validate a methodology for the numerical simulation of the fluid structure interaction in free surface flows. Specifically, this study concentrates on the vertical impact of a rigid body on the water surface, (i.e. on the hull slamming problem). The fluid flow is modeled through the volume of fluid methodology, and the structure dynamics is described by the Newton's second law. An iterative algorithm guarantees the tight coupling between the fluid and solid solvers, allowing the simulations of lightweight (i.e. buoyant) structures. The methodology is validated comparing numerical results to experimental data on the free fall of different rigid wedges. The correspondence between numerical results and independent experimental findings from literature evidences the reliability and the accuracy of the proposed approach.

  4. Investigation of ALEGRA shock hydrocode algorithms using an exact free surface jet flow solution.

    SciTech Connect

    Hanks, Bradley Wright.; Robinson, Allen Conrad

    2014-01-01

    Computational testing of the arbitrary Lagrangian-Eulerian shock physics code, ALEGRA, is presented using an exact solution that is very similar to a shaped charge jet flow. The solution is a steady, isentropic, subsonic free surface flow with significant compression and release and is provided as a steady state initial condition. There should be no shocks and no entropy production throughout the problem. The purpose of this test problem is to present a detailed and challenging computation in order to provide evidence for algorithmic strengths and weaknesses in ALEGRA which should be examined further. The results of this work are intended to be used to guide future algorithmic improvements in the spirit of test-driven development processes.

  5. Axial Flows in Kármán Vortices Due to Amplitude Modulation and a Free Surface

    NASA Astrophysics Data System (ADS)

    Voorhees, A.; Benaroya, H.; Wei, T.

    2000-11-01

    Fluid-structure interaction experiments were conducted in a large free-surface water tunnel facility using a low-mass ratio circular cylinder. The 2.54-cm cylinder was attached at the lower end to the tunnel floor by a leaf spring and the upper end protruded through the free surface. In this manner, the cylinder was free to oscillate as an inverted pendulum in response to the Kármán vortex shedding phenomenon. Far from the free-surface, strong axial flows directed toward the free-surface were observed along the cores of Kármán vortices shed from the oscillating cylinder; such flows were not observed for matched Reynolds number flows where the cylinder was held stationary. However, near the free-surface fluid motion along vortex cores traveled both up and down, i.e. to and from the free-surface. It has been found that this phenomenon is directly linked to an observed beating of the cylinder when the oscillation frequency approaches the cylinder's natural frequency. In this study, the Reynolds number based on cylinder diameter and free stream velocity was 3800. The problem to be discussed is that of the interaction between the amplitude modulated cylinder motion, the ensuing vortex-street, and the free-surface. These interactions will be described using DPIV measurements taken over a range of levels beneath the free-surface. A phenomenological description of the axial vortex induction process will be developed using Kármán vortex strength as a function of distance from the free-surface.

  6. Theory for source-responsive and free-surface film modeling of unsaturated flow

    USGS Publications Warehouse

    Nimmo, J.R.

    2010-01-01

    A new model explicitly incorporates the possibility of rapid response, across significant distance, to substantial water input. It is useful for unsaturated flow processes that are not inherently diffusive, or that do not progress through a series of equilibrium states. The term source-responsive is used to mean that flow responds sensitively to changing conditions at the source of water input (e.g., rainfall, irrigation, or ponded infiltration). The domain of preferential flow can be conceptualized as laminar flow in free-surface films along the walls of pores. These films may be considered to have uniform thickness, as suggested by field evidence that preferential flow moves at an approximately uniform rate when generated by a continuous and ample water supply. An effective facial area per unit volume quantitatively characterizes the medium with respect to source-responsive flow. A flow-intensity factor dependent on conditions within the medium represents the amount of source-responsive flow at a given time and position. Laminar flow theory provides relations for the velocity and thickness of flowing source-responsive films. Combination with the Darcy-Buckingham law and the continuity equation leads to expressions for both fluxes and dynamic water contents. Where preferential flow is sometimes or always significant, the interactive combination of source-responsive and diffuse flow has the potential to improve prediction of unsaturated-zone fluxes in response to hydraulic inputs and the evolving distribution of soil moisture. Examples for which this approach is efficient and physically plausible include (i) rainstorm-generated rapid fluctuations of a deep water table and (ii) space- and time-dependent soil water content response to infiltration in a macroporous soil. ?? Soil Science Society of America.

  7. Surface Ripples Generated in a Couette Flow with a Free Surface

    NASA Astrophysics Data System (ADS)

    Masnadi, N.; Washuta, N.; Duncan, J. H.

    2014-11-01

    Free surface ripples created by subsurface turbulence in the gap between a vertical surface-piercing moving wall and a parallel fixed wall are studied experimentally. The moving wall is created with the aide of a meter-wide stainless steel belt that travels horizontally in a loop around two rollers with vertically oriented axes, which are separated by 7.5 meters. One of the two 7.5-m-long belt sections between the rollers is in contact with the water in a large open-surface water tank and forms the moving wall. The fixed wall is an acrylic plate located 4 cm from the belt surface. The water surface ripples are measured in a plane normal to the belt using a cinematic LIF technique. Measurements are done at a location about 100 gap widths downstream of the leading edge of the fixed plate in order to have a fully developed flow condition. It is found that the overall RMS surface fluctuations increase linearly with belt speed. The frequency-domain spectra of the surface height fluctuation and its temporal derivative are computed at locations across the gap width and are used to explore the physics of the free surface motions. The support of the Office of Naval Research is gratefully acknowledged.

  8. Circular flow formation triggered by Marangoni convection in nematic liquid crystal films with a free surface.

    PubMed

    Choi, Hyunhee; Takezoe, Hideo

    2016-01-14

    We demonstrate circular flow formation at a surface in homeotropically oriented nematic liquid crystals with a free surface using focused laser beam irradiation. Under a weak laser power, a pit together with an associated circular bulge is formed: the Marangoni effect. Here a diverging molecular flow from the pit (thermocapillary flow) also induces director tilt in the radial direction. Upon increasing the laser power, the pit becomes deeper, and eventually evolves into a circular flow associated with a deeper pit and a subsidiary circular bulge or valley structure. This phenomenon is induced by escaping from excess deformation energy due to a bend deformation of the director. Actually, we confirmed that the circular flow is never formed in the isotropic phase. The handedness of the vortex cannot be controlled by circular polarisation, but is controllable by doping with chiral molecules. This rotational motion (a nematic micro-rotor) is a unique phenomenon only exhibited by anisotropic liquids, and is expected to be applied for novel devices. PMID:26482229

  9. Oscillating line source in a shear flow with a free surface: critical layer-like contributions

    NASA Astrophysics Data System (ADS)

    Ellingsen, Simen Å.; Tyvand, Peder A.

    2016-07-01

    The linearized water-wave radiation problem for an oscillating submerged line source in an inviscid shear flow with a free surface is investigated analytically at finite, constant depth in the presence of a shear flow varying linearly with depth. The surface velocity is taken to be zero relative to the oscillating source, so that Doppler effects are absent. The radiated wave out from the source is calculated based on Euler's equation of motion with the appropriate boundary and radiation conditions, and differs substantially from the solution obtained by assuming potential flow. To wit, an additional wave is found in the downstream direction in addition to the previously known dispersive wave solutions; this wave is non-dispersive and we show how it is the surface manifestation of a critical layer-like flow generated by the combination of shear and mass flux at the source, passively advected with the flow. As seen from a system moving at the fluid velocity at the source's depth, streamlines form closed curves in a manner similar to Kelvin's cat's eye vortices. A resonant frequency exists at which the critical wave resonates with the downstream propagating wave, resulting in a downstream wave pattern diverging linearly in amplitude away from the source.

  10. Channelized free-surface flow of cohesionless granular avalanches in a chute with shallow lateral curvature

    NASA Astrophysics Data System (ADS)

    Wieland, M.; Gray, J. M. N. T.; Hutter, K.

    1999-08-01

    A series of laboratory experiments and numerical simulations have been performed to investigate the rapid fluid-like flow of a finite mass of granular material down a chute with partial lateral confinement. The chute consists of a section inclined at 40° to the horizontal, which is connected to a plane run-out zone by a smooth transition. The flow is confined on the inclined section by a shallow parabolic cross-slope profile. Photogrammetric techniques have been used to determine the position of the evolving boundary during the flow, and the free-surface height of the stationary granular deposit in the run-out zone. The results of three experiments with different granular materials are presented and shown to be in very good agreement with numerical simulations based on the Savage Hutter theory for granular avalanches. The basal topography over which the avalanche flows has a strong channelizing effect on the inclined section of the chute. As the avalanche reaches the run-out zone, where the lateral confinement ceases, the head spreads out to give the avalanche a characteristic ‘tadpole’ shape. Sharp gradients in the avalanche thickness and velocity began to develop at the interface between the nose and tail of the avalanche as it came to rest, indicating that a shock wave develops close to the end of the experiments.

  11. Near-wake flow structure of elliptic cylinders close to a free surface: effect of cylinder aspect ratio

    NASA Astrophysics Data System (ADS)

    Daichin, K. V.; Lee, Sang Joon

    The flow fields behind elliptic cylinders adjacent to a free surface were investigated experimentally in a circulating water channel. A range of cylinder aspect ratios (AR=2, 3, 4) were considered, while the cross-sectional area of the elliptical cylinder was kept constant. The main objective of this study was to investigate the effect of cylinder aspect ratio and a free surface on the flow structure in the near-wake behind elliptic cylinders. For each elliptic cylinder, the flow structure was analyzed for various values of the submergence depth of the cylinder beneath the free surface. The flow fields were measured using a single-frame double-exposure PIV (Particle Image Velocimetry) system. For each experimental condition, 350 instantaneous velocity fields were obtained and ensemble-averaged to obtain the mean velocity field and spatial distribution of the mean vorticity statistics. The results show that near-wake can be classified into three typical flow patterns: formation of a Coanda flow, generation of substantial jet-like flow, and attachment of this jet flow to the free surface. The general flow structure observed behind the elliptic cylinders resembles the structure previously reported for a circular cylinder submerged near a free surface. However, the wake width and the angle of downward deflection of the shear layer developed from the lower surface of the elliptic cylinder differ from those observed for a circular cylinder. These trends are enhanced as cylinder aspect ratio is increased. In addition, the free surface distortion is also discussed in the paper.

  12. Performance and Near-Wake Flow field of A Marine Hydrokinetic Turbine Operating in Free surface Proximity

    NASA Astrophysics Data System (ADS)

    Banerjee, Arindam; Kolekar, Nitin

    2015-11-01

    The current experimental investigation aims at understanding the effect of free surface proximity and associated blockage on near-wake flow-field and performance of a three bladed horizontal axis marine hydrokinetic turbine. Experiments were conducted on a 0.14m radius, three bladed constant chord turbine in a 0.61m ×0.61m test section water channel. The turbine was subjected to various rotational speeds, flow speeds and depths of immersion. Experimental data was acquired through a submerged in-line thrust-torque sensor that was corrected to an unblocked dataset with a blockage correction using measured thrust data. A detailed comparison is presented between blocked and unblocked datasets to identify influence of Reynolds number and free surface proximity on blockage effects. The percent change in Cp was found to be dependent on flow velocity, rotational speed and free surface to blade tip clearance. Further, flow visualization using a stereoscopic particle image velocimetry was carried out in the near-wake region of turbine to understand the mechanism responsible for variation of Cp with rotational speed and free surface proximity. Results revealed presence of slower wake at higher rotational velocities and increased asymmetry in the wake at high free surface proximity.

  13. Free surface flow impact on a vertical wall: a numerical assessment

    NASA Astrophysics Data System (ADS)

    Pugliese Carratelli, Eugenio; Viccione, Giacomo; Bovolin, Vittorio

    2016-03-01

    The sudden impact of a free surface flow upon a solid wall is a common occurrence in many situations in nature and technology. The design of marine structures is probably the most obvious example, but also river and dam hydraulics as well as the necessity of understanding flood and debris flow-induced damage have led to theoretical and experimental work on the mechanism of fluid slamming loads. This is therefore a very old and rich research field, which has not yet reached full maturity, so that semi-empirical methods in design practice are still the rule in many sectors. Up-to-date CFD technology with both Eulerian and Lagrangian approaches is employed to investigate highly non-stationary fluid impact on a solid wall. The development of the pressure wave produced by the impact is examined as it propagates and interacts with the fluid boundaries, as well as the subsequent build-up of high-pressure gradients of high fluid velocities. The geometry and the velocity field of the problem considered are very simple, but the results seem to provide new insight, in particular, into the connection between phenomena with different timescales.

  14. Granular-front formation in free-surface flow of concentrated suspensions.

    PubMed

    Leonardi, Alessandro; Cabrera, Miguel; Wittel, Falk K; Kaitna, Roland; Mendoza, Miller; Wu, Wei; Herrmann, Hans J

    2015-11-01

    A granular front emerges whenever the free-surface flow of a concentrated suspension spontaneously alters its internal structure, exhibiting a higher concentration of particles close to its front. This is a common and yet unexplained phenomenon, which is usually believed to be the result of fluid convection in combination with particle size segregation. However, suspensions composed of uniformly sized particles also develop a granular front. Within a large rotating drum, a stationary recirculating avalanche is generated. The flowing material is a mixture of a viscoplastic fluid obtained from a kaolin-water dispersion with spherical ceramic particles denser than the fluid. The goal is to mimic the composition of many common granular-fluid materials, such as fresh concrete or debris flow. In these materials, granular and fluid phases have the natural tendency to separate due to particle settling. However, through the shearing caused by the rotation of the drum, a reorganization of the phases is induced, leading to the formation of a granular front. By tuning the particle concentration and the drum velocity, it is possible to control this phenomenon. The setting is reproduced in a numerical environment, where the fluid is solved by a lattice-Boltzmann method, and the particles are explicitly represented using the discrete element method. The simulations confirm the findings of the experiments, and provide insight into the internal mechanisms. Comparing the time scale of particle settling with the one of particle recirculation, a nondimensional number is defined, and is found to be effective in predicting the formation of a granular front. PMID:26651686

  15. Granular-front formation in free-surface flow of concentrated suspensions

    NASA Astrophysics Data System (ADS)

    Leonardi, Alessandro; Cabrera, Miguel; Wittel, Falk K.; Kaitna, Roland; Mendoza, Miller; Wu, Wei; Herrmann, Hans J.

    2015-11-01

    A granular front emerges whenever the free-surface flow of a concentrated suspension spontaneously alters its internal structure, exhibiting a higher concentration of particles close to its front. This is a common and yet unexplained phenomenon, which is usually believed to be the result of fluid convection in combination with particle size segregation. However, suspensions composed of uniformly sized particles also develop a granular front. Within a large rotating drum, a stationary recirculating avalanche is generated. The flowing material is a mixture of a viscoplastic fluid obtained from a kaolin-water dispersion with spherical ceramic particles denser than the fluid. The goal is to mimic the composition of many common granular-fluid materials, such as fresh concrete or debris flow. In these materials, granular and fluid phases have the natural tendency to separate due to particle settling. However, through the shearing caused by the rotation of the drum, a reorganization of the phases is induced, leading to the formation of a granular front. By tuning the particle concentration and the drum velocity, it is possible to control this phenomenon. The setting is reproduced in a numerical environment, where the fluid is solved by a lattice-Boltzmann method, and the particles are explicitly represented using the discrete element method. The simulations confirm the findings of the experiments, and provide insight into the internal mechanisms. Comparing the time scale of particle settling with the one of particle recirculation, a nondimensional number is defined, and is found to be effective in predicting the formation of a granular front.

  16. Velocity profiles and plug zones in a free surface viscoplastic flow : experimental study and comparison to shallow flow models

    NASA Astrophysics Data System (ADS)

    Freydier, Perrine; Chambon, Guillaume; Naaim, Mohamed

    2016-04-01

    Rheological studies concerning natural muddy debris flows have shown that these materials can be modelled as non-Newtonian viscoplastic fluids. These complex flows are generally represented using models based on a depth-integrated approach (Shallow Water) that take into account closure terms depending on the shape of the velocity profile. But to date, there is poor knowledge about the shape of velocity profiles and the position of the interface between sheared and unsheared regions (plug) in these flows, especially in the vicinity of the front. In this research, the internal dynamics of a free-surface viscoplastic flow down an inclined channel is investigated and compared to the predictions of a Shallow Water model based on the lubrication approximation. Experiments are conducted in an inclined channel whose bottom is constituted by an upward-moving conveyor belt with controlled velocity, which allows generating and observing gravity-driven stationary surges in the laboratory frame. Carbopol microgel has been used as a homogeneous and transparent viscoplastic fluid. High-resolution measurements of velocity field is performed through optical velocimetry techniques both in the uniform zone and within the front zone where flow thickness is variable and where recirculation takes place. Specific analyses have been developed to determine the position of the plug within the surge. Flow height is accessible through image processing and ultrasonic sensors. Sufficiently far from the front, experimental results are shown to be in good agreement with theoretical predictions regarding the velocity profiles and the flow height evolution. In the vicinity of the front, however, analysis of measured velocity profiles shows an evolution of the plug different from that predicted by lubrication approximation. Accordingly, the free surface shape also deviates from the predictions of the classical Shallow Water model. These results highlight the necessity to take into account higher

  17. Detection of liquid-metal, free-surface flow using the DLP measurement technique

    NASA Astrophysics Data System (ADS)

    Hillenbrand, M. P.; Stieglitz, R.; Neitzel, G. P.

    2012-01-01

    Novel accelerator applications favor free-surface liquid-metal flows, in which the liquid acts both as a target producing secondary particles but also to remove efficiently the heat deposited. A crucial aspect for the operation is the continuous monitoring of both shape and position of the liquid's surface. This demands, in a nuclear environment, a non-intrusive measurement technique with high temporal and spatial resolution. In this context, the double-layer projection (DLP) technique based on geometric optics has been developed, allowing one to detect either point-wise or area-wise the shape and position of the nearly totally reflecting liquid-metal surface. The DLP technique employs a laser beam projected through a coplanar glass plate to the surface from which it is reflected to the plate again. Beam locations captured by means of a camera permit the position and shape of the surface to be reconstructed. The parameters affecting the resolution and performance of the DLP technique are discussed. Additionally, validation studies using static and moving objects of pre-defined shape are conducted, exhibiting spatial and temporal resolutions of 300 μm and 100 Hz, respectively. Finally, the DLP system is applied to perform measurements of a circular hydraulic jump (CHJ) in a liquid metal. The DLP system has proved the capability to measure the jump both qualitatively and quantitatively. Additionally, the experiments identified, at high Reynolds numbers, the existence of a two-step jump. The analysis of spectral data of the DLP surface measurements shows clearly that, at the outer radius, gravity waves occur. Also, contributions from the pump oscillations were found, demonstrating the high performance of the DLP system.

  18. A new numerical framework to simulate viscoelastic free-surface flows with the finite-volume method

    NASA Astrophysics Data System (ADS)

    Comminal, R.; Spangenberg, J.; Hattel, J. H.

    2015-04-01

    A new method for the simulation of 2D viscoelastic flow is presented. Numerical stability is obtained by the logarithmic-conformation change of variable, and a fully-implicit pure-streamfunction flow formulation, without use of any artificial diffusion. As opposed to other simulation results, our calculations predict a hydrodynamic instability in the 4:1 contraction geometry at a Weissenberg number of order 4. This new result is in qualitative agreement with the prediction of a non-linear subcritical elastic instability in Poiseuille flow. Our viscoelastic flow solver is coupled with a volume-of-fluid solver in order to predict free- surfaces in extrusion.

  19. On the solution of transient free-surface flow problems in porous media by a fixed-domain method

    NASA Astrophysics Data System (ADS)

    Lin, Chin-Shing; Bruch, John C.; Sloss, James M.; Comincioli, Valeriano

    1984-03-01

    The numerical model presented here is the solution to the exact initial-boundary-value problems arising in recharge fluid flow through porous media having a free surface. Since the problem is nonlinear and includes a moving boundary, a numerical solution is obtained by using a fixed-domain approach. The Baiocchi transformation and method are used to develop a boundary-value problem which is then solved by an iterative method of successive over-relaxation type. Transient free-surface seepage through a two-dimensional dam with accretion is presented as an example problem. The effects of hydraulic conductivity, specific storativity and accretion on the seepage flow are studied. Two modified cases are satisfactorily compared with published results.

  20. [Effect of free surface flow wetland and subsurface flow wetland on bacterial diversity in Beijing Cuihu Wetland Park].

    PubMed

    Wang, Xiao-dan; Zhai, Zhen-hua; Zhao, Shuang; Li, Rong-qi; Ma, Wen-lin; Li, Yan-hong

    2009-01-01

    To achieve the effects of artificial wetland on the bacterial diversity, the culturable bacteria and total cell counts of three wetland cells, including sewage pond (SP), free surface wetland (SF) and subsurface flow wetland (SSF), were investigated using the traditional culture-dependent approach and flow cytometry method, based on the detecting the water quality. The bacterial diversity and dominant groups were also compared by PCR-DGGE profiles and 16S rDNA library technique based on its V3 region. Results show that SF and SSF cells can remove the nutrients effectively, the highest removal ratio of COD, total nitrogen, and total phosphorus reach to 42.33%, 52.92% and 41.4%, respectively; The total microbes are increased continuously with the treatment by SF and SSF, and the culturable bacteria clones are decreased after treatment by SF, and increased after further train by SSF. The Shannon-Weaver index is increased to 3.2850 from 3.0819 while the water flowing through SF, but decreased to 3.0181 after flowing through SSF; The dominant groups in SP include Actinobacteria, Cyanobacteria and alpha-Proteobacteria, reach to 38%, 18% and 18%, respectively; but the most dominant bacteria is changed to beta-Proteobacteria with the ratio of 32% and 44%, after treatment by SF and SSF, respectively. Cytophagal Flexibacter/Bacteroides (CFB) phylum is also increased to 24% finally. Therefore, while the Cuihu Wetland removing the nutrients,the bacterial counts, diversity and dominant groups are also changed,some beneficial bacteria in beta-Proteobacteria and CFB phylum increased, and part of those deleterious bacteria in Actinobacteria and Cyanobacteria decreased. PMID:19353894

  1. An explicit Lagrangian finite element method for free-surface weakly compressible flows

    NASA Astrophysics Data System (ADS)

    Cremonesi, Massimiliano; Meduri, Simone; Perego, Umberto; Frangi, Attilio

    2016-07-01

    In the present work, an explicit finite element approach to the solution of the Lagrangian formulation of the Navier-Stokes equations for weakly compressible fluids or fluid-like materials is investigated. The introduction of a small amount of compressibility is shown to allow for the formulation of a fast and robust explicit solver based on a particle finite element method. Newtonian and Non-Newtonian Bingham laws are considered. A barotropic equation of state completes the model relating pressure and density fields. The approach has been validated through comparison with experimental tests and numerical simulations of free surface fluid problems involving water and water-soil mixtures.

  2. Experimental study of thermocapillary flows in a thin liquid layer with heat fluxes imposed on the free surface

    NASA Technical Reports Server (NTRS)

    Lai, Chun-Liang; Greenberg, Paul S.; Chai, An-Ti

    1988-01-01

    To study thermocapillary flows in a two-dimensional thin liquid layer with heat fluxes imposed on the free surface experimentally, a long tray configuration was employed to simulate the infinite layer. The surface temperature distribution due to thermocapillary convection for different flow regimes was measured and compared with theorectical predictions. A short tray configuration was also employed to study the end wall effects (insulating or conducting). The results show that, for a strong convection flow with an insulating wall as the boundary, the surface temperature distribution became quite uniform. Consequently, the thermocapillary driving force was greatly reduced. On the other hand, a strong fluid motion always existed adjacent to the conducting wall because of the large surface temperature gradient near the wall.

  3. Experimental study of thermocapillary flows in a thin liquid layer with heat fluxes imposed on the free surface

    NASA Technical Reports Server (NTRS)

    Lai, Chun-Liang; Greenberg, Paul S.; Chai, An-Ti

    1988-01-01

    To study thermocapillary flows in a two-dimensional thin liquid layer with heat fluxes imposed on the free surface experimentally, a long tray configuration was employed to simulate the infinite layer. The surface temperature distribution due to thermocapillary convective for different flow regimes was measured and compared with theoretical predictions. A short tray configuration was also employed to study the end wall effects (insulating or conducting). The results show that for a strong convection flow with an insulating wall as the boundary the surface temperature distribution became quite uniform. Consequently, the thermocapillary driving force was greatly reduced. On the other hand, a strong fluid motion always existed adjacent to the conducting wall because of the large surface temperature gradient near the wall.

  4. A Finite Element Method for Free-Surface Flows of Incompressible Fluids in Three Dimensions, Part II: Dynamic Wetting Lines

    SciTech Connect

    Baer, T.A.; Cairncross, R.A.; Rao, R.R.; Sackinger, P.A.; Schunk, P.R.

    1999-01-29

    To date, few researchers have solved three-dimensional free-surface problems with dynamic wetting lines. This paper extends the free-surface finite element method described in a companion paper [Cairncross, R.A., P.R. Schunk, T.A. Baer, P.A. Sackinger, R.R. Rao, "A finite element method for free surface flows of incompressible fluid in three dimensions, Part I: Boundary-Fitted mesh motion.", to be published (1998)] to handle dynamic wetting. A generalization of the technique used in two dimensional modeling to circumvent double-valued velocities at the wetting line, the so-called kinematic paradox, is presented for a wetting line in three dimensions. This approach requires the fluid velocity normal to the contact line to be zero, the fluid velocity tangent to the contact line to be equal to the tangential component of web velocity, and the fluid velocity into the web to be zero. In addition, slip is allowed in a narrow strip along the substrate surface near the dynamic contact line. For realistic wetting-line motion, a contact angle which varies with wetting speed is required because contact lines in three dimensions typically advance or recede a different rates depending upon location and/or have both advancing and receding portions. The theory is applied to capillary rise of static fluid in a corner, the initial motion of a Newtonian droplet down an inclined plane, and extrusion of a Newtonian fluid from a nozzle onto a moving substrate. The extrusion results are compared to experimental visualization. Subject Categories

  5. Internal dynamics of a free-surface viscoplastic flow down an inclined plane: experimental results through PIV measurements

    NASA Astrophysics Data System (ADS)

    Freydier, Perrine; Chambon, Guillaume; Naaim, Mohamed

    2015-04-01

    Debris flows constitute one of the most important natural hazards throughout the mountainous regions of the world, causing significant damages and economic losses. These mass are composed of particles of all sizes from clay to boulders suspended in a viscous fluid. An important goal resides in developing models that are able to accurately predict the hydraulic properties of debris flows. First, these flows are generally represented using models based on a momentum integral approach that consists in assuming a shallow flow and in depth averaging the local conservation equations. These models take into account closure terms depending on the shape of the velocity profile inside the flow. Second, the specific migration mechanisms of the suspended particles, which have a strong influence on the propagation of the surges, also depend on the internal dynamics within the flow. However, to date, few studies concerning the internal dynamics in particular in the vicinity of the front, of such flows have been carried out. The aim of this study is to document the internal dynamics in free-surface viscoplastic flows down an inclined channel. The rheological studies concerning natural muddy debris flows, rich in fine particles, have shown that these materials can be modeled, at least as a first approximation as non-Newtonian viscoplastic fluids. Experiments are conducted in an inclined channel whose bottom is constituted by an upward-moving conveyor belt with controlled velocity. Carbopol microgel has been used as a homogeneous transparent viscoplastic fluid. This experimental setup allows generating and monitoring stationary gravity-driven surges in the laboratory frame. We use PIV technique (Particle Image Velocimetry) to obtain velocity fields both in the uniform zone and within the front zone where flow thickness is variable and where recirculation takes place. Experimental velocity profiles and determination of plug position will be presented and compared to theoretical

  6. Continuation in a parameter - Experience with viscous and free surface flows

    NASA Technical Reports Server (NTRS)

    Kheshgi, H. S.; Basaran, O. A.; Benner, R. E.; Kistler, S. F.; Scriven, L. E.

    1983-01-01

    The results of modifications in continuation methods applied to obtain solutions to the Navier-Stokes systems of equations for incompressible, two-dimensional, steady flows are reported. It is shown that parameter continuation permits prediction of accurate, initial estimates for iterative processing of nonlinear finite difference and finite element equations of motions. The new parameter steps are derived from values of the preceding parameter steps. The accuracy of the estimates is ensured with appropriate choices of the step size. The continuation predictor/iterative corrector is demonstrated to trace the branches of parameter space along which steady flow states are found, and techniques are available for tracing multiply branching paths. The techniques are applied to solving the Navier-Stokes equations for flow through a rotating square channel, the formation of a falling liquid curtain, and gyrostatic equilibria of rotating cylindrical drops.

  7. Comparative performance of free surface and sub-surface flow systems in the phytoremediation of hydrocarbons using Scirpus grossus.

    PubMed

    Al-Baldawi, Israa Abdul Wahab; Abdullah, Siti Rozaimah Sheikh; Suja, Fatihah; Anuar, Nurina; Mushrifah, Idris

    2013-11-30

    Two types of flow system, free surface flow (FSF) and sub-surface flow (SSF), were examined to select a better way to remove total petroleum hydrocarbons (TPH) using diesel as a hydrocarbon model in a phytotoxicity test to Scirpus grossus. The removal efficiencies of TPH for the two flow systems were compared. Several wastewater parameters, including temperature (T, °C), dissolved oxygen (DO, mgL(-1)), oxidation-reduction potential (ORP, mV), and pH were recorded during the experimental runs. In addition, overall plant lengths, wet weights, and dry weights were also monitored. The phytotoxicity test using the bulrush plant S. grossus was run for 72 days with different diesel concentrations (1%, 2%, and 3%) (Vdiesel/Vwater). A comparison between the two flow systems showed that the SSF system was more efficient than the FSF system in removing TPH from the synthetic wastewater, with average removal efficiencies of 91.5% and 80.2%, respectively. The SSF system was able to tolerate higher diesel concentrations than was the FSF system. PMID:24113536

  8. Analysis of free-surface flows through energy considerations: Single-phase versus two-phase modeling

    NASA Astrophysics Data System (ADS)

    Marrone, Salvatore; Colagrossi, Andrea; Di Mascio, Andrea; Le Touzé, David

    2016-05-01

    The study of energetic free-surface flows is challenging because of the large range of interface scales involved due to multiple fragmentations and reconnections of the air-water interface with the formation of drops and bubbles. Because of their complexity the investigation of such phenomena through numerical simulation largely increased during recent years. Actually, in the last decades different numerical models have been developed to study these flows, especially in the context of particle methods. In the latter a single-phase approximation is usually adopted to reduce the computational costs and the model complexity. While it is well known that the role of air largely affects the local flow evolution, it is still not clear whether this single-phase approximation is able to predict global flow features like the evolution of the global mechanical energy dissipation. The present work is dedicated to this topic through the study of a selected problem simulated with both single-phase and two-phase models. It is shown that, interestingly, even though flow evolutions are different, energy evolutions can be similar when including or not the presence of air. This is remarkable since, in the problem considered, with the two-phase model about half of the energy is lost in the air phase while in the one-phase model the energy is mainly dissipated by cavity collapses.

  9. Analysis of free-surface flows through energy considerations: Single-phase versus two-phase modeling.

    PubMed

    Marrone, Salvatore; Colagrossi, Andrea; Di Mascio, Andrea; Le Touzé, David

    2016-05-01

    The study of energetic free-surface flows is challenging because of the large range of interface scales involved due to multiple fragmentations and reconnections of the air-water interface with the formation of drops and bubbles. Because of their complexity the investigation of such phenomena through numerical simulation largely increased during recent years. Actually, in the last decades different numerical models have been developed to study these flows, especially in the context of particle methods. In the latter a single-phase approximation is usually adopted to reduce the computational costs and the model complexity. While it is well known that the role of air largely affects the local flow evolution, it is still not clear whether this single-phase approximation is able to predict global flow features like the evolution of the global mechanical energy dissipation. The present work is dedicated to this topic through the study of a selected problem simulated with both single-phase and two-phase models. It is shown that, interestingly, even though flow evolutions are different, energy evolutions can be similar when including or not the presence of air. This is remarkable since, in the problem considered, with the two-phase model about half of the energy is lost in the air phase while in the one-phase model the energy is mainly dissipated by cavity collapses. PMID:27300984

  10. Instability on the Free Surface of Superfluid He-II Induced by a Steady Heat Flow in Bulk

    NASA Astrophysics Data System (ADS)

    Remizov, I. A.; Levchenko, A. A.; Mezhov-Deglin, L. P.

    2016-06-01

    We report observations of the onset of irregular motion on a free surface of superfluid He-II induced by a quasi-stationary heat flow in a rectangular container. The container open from the top is mounted inside an optical cell partly filled with superfluid He-II. Three holes in the container walls provide free circulation of the normal and superfluid components inside and outside the container. The results of measurements are discussed in terms of the Korshunov theory (Eurphys Lett 16:673, 1991; JETP Lett 75:423, 2002) of the Kelvin-Helmholtz instability on an initially flat He-II surface induced by a relative motion of superfluid and normal components of the liquid along the surface when the counterflow velocity exceeds the threshold value. The experimental data are qualitatively consistent with the theoretical predictions (Korshunov in JETP Lett 75:423, 2002) taking into account the finite viscosity of He-II.

  11. Distribution of resistive body-force in curved free-surface flow

    NASA Technical Reports Server (NTRS)

    Sivakumaran, N. S.; Dressler, R. F.

    1986-01-01

    The customary procedure for including resistive effects in turbulent hydraulic and stratified atmospheric flows is to integrate the empirically-known boundary shears over the entire wetted boundary of a thin fluid slab. A resistive body-force is then assumed to exist everywhere in each slab to replace the boundary shearing force. For the classical Saint-Venant (1871) model, this body-force can be shown to have a constant distribution in the vertical direction, and therefore can be evaluated for use in the momentum differential equation. In the newer Dressler theory (1978), however, for unsteady flow over curved beds, it is proved here that a constant body-force distribution is not possible. Its variable distribution is determined as well as its magnitude for use in the curved-flow equations. This variable distribution acts to produce an equal resultant in every thin layer of fluid parallel to the bed in an angular wedge over the curved channel bed. The new curved-flow equations are therefore extended to include resistive effects.

  12. Plane Stokes flow driven by capillarity on the free surfaces of a doubly-connected region

    SciTech Connect

    Hopper, R.W.

    1991-01-07

    The free creeping viscous incompressible plant flow a finite region, bounded by a simple smooth closed curve and driven solely by surface tension, was analyzed previously. The shape evolution was described in terms of a time-dependent mapping function z = {Omega}({zeta},t) of the unit circle, conformal on {vert bar}{zeta}{vert bar} {le} 1. An equation giving the time evolution of the mapping, typically in parametric form, was derived. The theory is here extended to doubly-connected regions mapped from an annulus. It is found that the conjectured parametric map must satisfy three conditions. The elementary problem of the collapse of a concentric circular annulus is easily recovered, but no non-trivial flows have been discovered. The theory is used to show that confocal elliptic ring does not collapse through a sequence of confocal elliptic rings. 5 refs., 1 fig.

  13. Analysis of pipe flow with free surface. Part II. Theoretical analysis and experiment

    NASA Astrophysics Data System (ADS)

    Tanaka, Amane; Takaki, Ryuji

    1994-05-01

    Flow field near the front of an incompressible viscous fluid pushed into a circular pipe is analyzed theoretically and observed experimentally. In the theory, an approximated stream function for a steady state near the axis of the pipe is obtained by use of the Stokes equation. In the experiment, the shape of the surface was observed by a video camera. The theoretical velocity profile and the surface shape near the axis coincide with those from computation (Part I) and experiment.

  14. Interfacial stress balances in structured continua and free surface flows in ferrofluids

    NASA Astrophysics Data System (ADS)

    Chaves, Arlex; Rinaldi, Carlos

    2014-04-01

    Interfacial linear and internal angular momentum balances are obtained for a structured continuum and for the special case of a ferrofluid, a suspension of magnetic nanoparticles in a Newtonian fluid. The interfacial balance equations account for the effects of surface tension and surface tension gradient, magnetic surface excess forces, antisymmetric stresses, and couple stresses in driving interfacial flows in ferrofluids. Application of the interfacial balance equations is illustrated by obtaining analytical expressions for the translational and spin velocity profiles in a thin film of ferrofluid on an infinite flat plate when a rotating magnetic field is applied with axis of rotation parallel to the ferrofluid/air interface. The cases of zero and non-zero spin viscosity are considered for small applied magnetic field amplitude. Expressions for the maximum translational velocity, slope of the translational velocity profile at the ferrofluid/air interface, and volumetric flow rate are obtained and their use to test the relevance of spin viscosity and couple stresses in the flow situation under consideration is discussed.

  15. Simulation of the 3D viscoelastic free surface flow by a parallel corrected particle scheme

    NASA Astrophysics Data System (ADS)

    Jin-Lian, Ren; Tao, Jiang

    2016-02-01

    In this work, the behavior of the three-dimensional (3D) jet coiling based on the viscoelastic Oldroyd-B model is investigated by a corrected particle scheme, which is named the smoothed particle hydrodynamics with corrected symmetric kernel gradient and shifting particle technique (SPH_CS_SP) method. The accuracy and stability of SPH_CS_SP method is first tested by solving Poiseuille flow and Taylor-Green flow. Then the capacity for the SPH_CS_SP method to solve the viscoelastic fluid is verified by the polymer flow through a periodic array of cylinders. Moreover, the convergence of the SPH_CS_SP method is also investigated. Finally, the proposed method is further applied to the 3D viscoelastic jet coiling problem, and the influences of macroscopic parameters on the jet coiling are discussed. The numerical results show that the SPH_CS_SP method has higher accuracy and better stability than the traditional SPH method and other corrected SPH method, and can improve the tensile instability. Project supported by the Natural Science Foundation of Jiangsu Province, China (Grant Nos. BK20130436 and BK20150436) and the Natural Science Foundation of the Higher Education Institutions of Jiangsu Province, China (Grant No. 15KJB110025).

  16. Interfacial stress balances in structured continua and free surface flows in ferrofluids

    SciTech Connect

    Chaves, Arlex; Rinaldi, Carlos

    2014-04-15

    Interfacial linear and internal angular momentum balances are obtained for a structured continuum and for the special case of a ferrofluid, a suspension of magnetic nanoparticles in a Newtonian fluid. The interfacial balance equations account for the effects of surface tension and surface tension gradient, magnetic surface excess forces, antisymmetric stresses, and couple stresses in driving interfacial flows in ferrofluids. Application of the interfacial balance equations is illustrated by obtaining analytical expressions for the translational and spin velocity profiles in a thin film of ferrofluid on an infinite flat plate when a rotating magnetic field is applied with axis of rotation parallel to the ferrofluid/air interface. The cases of zero and non-zero spin viscosity are considered for small applied magnetic field amplitude. Expressions for the maximum translational velocity, slope of the translational velocity profile at the ferrofluid/air interface, and volumetric flow rate are obtained and their use to test the relevance of spin viscosity and couple stresses in the flow situation under consideration is discussed.

  17. SPH-DCDEM model for arbitrary geometries in free surface solid-fluid flows

    NASA Astrophysics Data System (ADS)

    Canelas, Ricardo B.; Crespo, Alejandro J. C.; Domínguez, Jose M.; Ferreira, Rui M. L.; Gómez-Gesteira, Moncho

    2016-05-01

    A unified discretization of rigid solids and fluids is introduced, allowing for resolved simulations of fluid-solid phases within a meshless framework. The numerical solution, attained by Smoothed Particle Hydrodynamics (SPH) and a variation of Discrete Element Method (DEM), the Distributed Contact Discrete Element Method (DCDEM) discretization, is achieved by directly considering solid-solid and solid-fluid interactions. The novelty of the work is centred on the generalization of the coupling of the DEM and SPH methodologies for resolved simulations, allowing for state-of-the-art contact mechanics theories to be used in arbitrary geometries, while fluid to solid and vice versa momentum transfers are accurately described. The methods are introduced, analysed and discussed. Initial validations on the DCDEM and the fluid coupling are presented, drawing from test cases in the literature. An experimental campaign serves as a validation point for complex, large scale solid-fluid flows, where a set of blocks in several configurations is subjected to a dam-break wave. Blocks are tracked and positions are then compared between experimental data and the numerical solutions. A Particle Image Velocimetry (PIV) technique allows for the quantification of the flow field and direct comparison with numerical data. The results show that the model is accurate and is capable of treating highly complex interactions, such as transport of debris or hydrodynamic actions on structures, if relevant scales are reproduced.

  18. A new three-dimensional terrain-following tidal model of free-surface flows

    NASA Astrophysics Data System (ADS)

    Lu, Fuqiang; Zhang, Zhuo; Song, Zhiyao; Yue, Songshan; Wen, Yongning

    2015-12-01

    A three-dimensional hydrodynamic model is presented which combines a terrain-following vertical coordinate with a horizontally orthogonal curvilinear coordinate system to fit the complex bottom topography and coastlines near estuaries, continental shelves, and harbors. To solve the governing equations more efficiently, we improve the alternating direction implicit method, which is extensively used in the numerical modeling of horizontal two-dimensional shallow water equations, and extend it to a three-dimensional tidal model with relatively little computational effort. Through several test cases and realistic applications, as presented in the paper, it can be demonstrated that the model is capable of simulating the periodic to-and-fro currents, wind-driven flow, Ekman spirals, and tidal currents in the near-shore region.

  19. Asymptotic and numerical analysis of free surface flows: Lump solitons and wave turbulence

    NASA Astrophysics Data System (ADS)

    Berger, Kurt Michael

    Three-dimensional solitary waves or lump solitons are known to be solutions to the Kadomtsev-Petviashvili I (KP-I) equation, which models small-amplitude shallow-water waves when the Bond number is greater than ⅓. Recently, Pego and Quintero presented a proof of the existence of such waves for the Benney-Luke equation with surface tension. Here we establish an explicit connection between the lump solitons of these two equations and numerically compute the Benney-Luke lump solitons and their speed-amplitude relation. Furthermore, we numerically collide two Benney-Luke lump solitons to illustrate their soliton wave character. Finally, we study the flow over an obstacle near the linear shallow-water speed and show that three-dimensional lump solitons are periodically generated. In the second part of this dissertation, our goal is to study, numerically, the statistics of a large number of interacting finite-depth gravity surface waves. The weak- or wave-turbulence problem consists of finding statistical states with constant flux of energy in wavenumber space. These states are obtained by forcing and dissipating the conservative water wave problem at disparate scales and predicting the spectrum, often as a Kolmogorov-like power law, at intermediate scales. Majda, McLaughlin, and Tabak started the numerical investigation of the predictions of weak turbulence theory using a nonlinear dispersive NLS model equation. Here we investigate wave turbulence in a manner similar to Majda et al, but for an equation modeling gravity water waves, which is the original context in which the problem was posed. We perform long time computations on the one-dimensional, finite-depth Benney-Luke equation and compute various statistical quantities of interest. To validate this model, we first show, analytically and numerically, that Benney-Luke equations correctly predict the main deterministic aspects of resonant gravity wave interactions: resonant quartets, Benjamin-Feir type wave

  20. Plane stokes flow driven by capillarity on a free surface: Overview and status

    SciTech Connect

    Hopper, R.W.

    1991-10-25

    This article summarizes some recent work on the creeping viscous incompressible plane flow in a region, bounded by a simple smooth closed curve and driven solely by surface tension. Such problems are self-contained in that the applied tractions are intrinsic in the geometry. The objective is to determine exactly the time evolution of the shape of the region. The problems are fundamentally nonlinear due to the large changes in shape, and it is emphasized that no mathematical approximations are made. For finite regions, the shape in the complex z-plane is described in terms of a time-dependent conformal mapping function {Omega}({zeta}, t) on the fixed region {vert bar} {zeta} {vert bar} {le} 1 of the complex {zeta}-plane. In practice, it has been necessary to conjecture an explicit parametric form {Omega}({zeta};{alpha}{sub 1}(t), {alpha}{sub 2}(t), {hor ellipsis}) whose validity must be verified using the shape- evolution equation. Suitable parameterizations are not always obvious. When the conjectured form holds and the equations can be solved, the evolution of the shape with time is obtained in simple, exact and closed form except for the value of the time, which requires a mere quadrature. Internal velocity and stress fields can be obtained.

  1. Plane stokes flow driven by capillarity on a free surface: Overview and status. Revision 2

    SciTech Connect

    Hopper, R.W.

    1991-10-25

    This article summarizes some recent work on the creeping viscous incompressible plane flow in a region, bounded by a simple smooth closed curve and driven solely by surface tension. Such problems are self-contained in that the applied tractions are intrinsic in the geometry. The objective is to determine exactly the time evolution of the shape of the region. The problems are fundamentally nonlinear due to the large changes in shape, and it is emphasized that no mathematical approximations are made. For finite regions, the shape in the complex z-plane is described in terms of a time-dependent conformal mapping function {Omega}({zeta}, t) on the fixed region {vert_bar} {zeta} {vert_bar} {le} 1 of the complex {zeta}-plane. In practice, it has been necessary to conjecture an explicit parametric form {Omega}[{zeta};{alpha}{sub 1}(t), {alpha}{sub 2}(t), {hor_ellipsis}] whose validity must be verified using the shape- evolution equation. Suitable parameterizations are not always obvious. When the conjectured form holds and the equations can be solved, the evolution of the shape with time is obtained in simple, exact and closed form except for the value of the time, which requires a mere quadrature. Internal velocity and stress fields can be obtained.

  2. Statistical analysis of turbulent super-streamwise vortices based on observations of streaky structures near the free surface in the smooth open channel flow

    NASA Astrophysics Data System (ADS)

    Zhong, Qiang; Chen, Qigang; Wang, Hao; Li, Danxun; Wang, Xingkui

    2016-05-01

    Long streamwise-elongated high- and low-speed streaks are repeatedly observed near the free surface in open channel flows in natural rivers and lab experiments. Super-streamwise vortex model has been proposed to explain this widespread phenomenon for quite some time. However, statistical evidence of the existence of the super-streamwise vortices as one type of coherent structures is still insufficient. Correlation and proper orthogonal decomposition (POD) analysis based on PIV experimental data in the streamwise-spanwise plane near the free surface in a smooth open channel flow are employed to investigate this topic. Correlation analysis revealed that the streaky structures appear frequently near the free surface and their occurrence probability at any spanwise position is equal. The spanwise velocity fluctuation usually flows from low-speed streaks toward high-speed streaks. The average spanwise width and spacing between neighboring low (or high) speed streaks are approximately h and 2h respectively. POD analysis reveals that there are streaks with different spanwise width in the instantaneous flow fields. Typical streamwise rotational movement can be sketched out directly based on the results from statistical analyses. Point-by-point analysis indicates that this pattern is consistent everywhere in the measurement window and is without any inhomogeneity in the spanwise direction, which reveals the essential difference between coherent structures and secondary flow cells. The pattern found by statistical analysis is consistent with the notion that the super-streamwise vortices exist universally as one type of coherent structure in open channel flows.

  3. Application of the methods of gas dynamics to water flows with free surface I : flows with no energy dissipation

    NASA Technical Reports Server (NTRS)

    Preiswerk, Ernst

    1940-01-01

    The application is treated in sufficient detail to facilitate as much as possible its application by the engineer who is less familiar with the subject. The present work was undertaken with two objects in view. In the first place, it is considered as a contribution to the water analogy of gas flows, and secondly, a large portion is devoted to the general theory of the two-dimensional supersonic flows.

  4. Implicit solution of the material transport in Stokes flow simulation: Toward thermal convection simulation surrounded by free surface

    NASA Astrophysics Data System (ADS)

    Furuichi, Mikito; May, Dave A.

    2015-07-01

    We present implicit time integration schemes suitable for modeling free surface Stokes flow dynamics with marker in cell (MIC) based spatial discretization. Our target is for example thermal convection surrounded by deformable surface boundaries to simulate the long term planetary formation process. The numerical system becomes stiff when the dynamical balancing time scale for the increasing/decreasing load by surface deformation is very short compared with the time scale associated with thermal convection. Any explicit time integration scheme will require very small time steps; otherwise, serious numerical oscillation (spurious solutions) will occur. The implicit time integration scheme possesses a wider stability region than the explicit method; therefore, it is suitable for stiff problems. To investigate an efficient solution method for the stiff Stokes flow system, we apply first (backward Euler (BE)) and second order (trapezoidal method (TR) and trapezoidal rule-backward difference formula (TR-BDF2)) accurate implicit methods for the MIC solution scheme. The introduction of implicit time integration schemes results in nonlinear systems of equations. We utilize a Jacobian free Newton Krylov (JFNK) based Newton framework to solve the resulting nonlinear equations. In this work we also investigate two efficient implicit solution strategies to reduce the computational cost when solving stiff nonlinear systems. The two methods differ in how the advective term in the material transport evolution equation is treated. We refer to the method that employs Lagrangian update as "fully implicit" (Imp), whilst the method that employs Eulerian update is referred to as "semi-implicit" (SImp). Using a finite difference (FD) method, we have performed a series of numerical experiments which clarify the accuracy of solutions and trade-off between the computational cost associated with the nonlinear solver and time step size. In comparison with the general explicit Euler method

  5. A finite difference technique for solving a time strain separable K-BKZ constitutive equation for two-dimensional moving free surface flows

    NASA Astrophysics Data System (ADS)

    Tomé, M. F.; Bertoco, J.; Oishi, C. M.; Araujo, M. S. B.; Cruz, D.; Pinho, F. T.; Vynnycky, M.

    2016-04-01

    This work is concerned with the numerical solution of the K-BKZ integral constitutive equation for two-dimensional time-dependent free surface flows. The numerical method proposed herein is a finite difference technique for simulating flows possessing moving surfaces that can interact with solid walls. The main characteristics of the methodology employed are: the momentum and mass conservation equations are solved by an implicit method; the pressure boundary condition on the free surface is implicitly coupled with the Poisson equation for obtaining the pressure field from mass conservation; a novel scheme for defining the past times t‧ is employed; the Finger tensor is calculated by the deformation fields method and is advanced in time by a second-order Runge-Kutta method. This new technique is verified by solving shear and uniaxial elongational flows. Furthermore, an analytic solution for fully developed channel flow is obtained that is employed in the verification and assessment of convergence with mesh refinement of the numerical solution. For free surface flows, the assessment of convergence with mesh refinement relies on a jet impinging on a rigid surface and a comparison of the simulation of a extrudate swell problem studied by Mitsoulis (2010) [44] was performed. Finally, the new code is used to investigate in detail the jet buckling phenomenon of K-BKZ fluids.

  6. Application of the Methods of Gas Dynamics to Water Flows with Free Surface II : Flows with Momentum Discontinuities (hydraulic Jumps)

    NASA Technical Reports Server (NTRS)

    Preiswerk, Ernst

    1940-01-01

    In this paper an introduction to shock polar diagrams is given which then leads into an examination of water depths in hydraulic jumps. Energy loss during these jumps is considered along with an extended look at elementary solutions of flow. An experimental test set-up is described and the results presented.

  7. A numerical study of steady 2D flow around NACA 0015 and NACA 0012 hydrofoil with free surface using VOF method

    NASA Astrophysics Data System (ADS)

    Adjali, Saadia; Belkadi, Mustapha; Aounallah, Mohammed; Imine, Omar

    2015-05-01

    Accurate simulation of turbulent free surface flows around surface ships has a central role in the optimal design of such naval vessels. The flow problem to be simulated is rich in complexity and poses many modeling challenges because of the existence of breaking waves around the ship hull, and because of the interaction of the two-phase flow with the turbulent boundary layer. In this paper, our goal is to estimate the lift and drag coefficients for NACA 0012 of hydrofoil advancing in calm water under steady conditions with free surface and emerged NACA 0015. The commercial CFD software FLUENT version 14 is used for the computations in the present study. The calculated grid is established using the code computer GAMBIT 2.3.26.The shear stress k-ωSST model is used for turbulence modeling and the volume of fluid technique is employed to simulate the free-surface motion. In this computation, the second order upwind scheme is used for discretizing the convection terms in the momentum transport equations, the Modified HRIC scheme for VOF discretisation. The results obtained compare well with the experimental data.

  8. Lithium-Based High Energy Density Flow Batteries

    NASA Technical Reports Server (NTRS)

    Bugga, Ratnakumar V. (Inventor); West, William C. (Inventor); Kindler, Andrew (Inventor); Smart, Marshall C. (Inventor)

    2014-01-01

    Systems and methods in accordance with embodiments of the invention implement a lithium-based high energy density flow battery. In one embodiment, a lithium-based high energy density flow battery includes a first anodic conductive solution that includes a lithium polyaromatic hydrocarbon complex dissolved in a solvent, a second cathodic conductive solution that includes a cathodic complex dissolved in a solvent, a solid lithium ion conductor disposed so as to separate the first solution from the second solution, such that the first conductive solution, the second conductive solution, and the solid lithium ionic conductor define a circuit, where when the circuit is closed, lithium from the lithium polyaromatic hydrocarbon complex in the first conductive solution dissociates from the lithium polyaromatic hydrocarbon complex, migrates through the solid lithium ionic conductor, and associates with the cathodic complex of the second conductive solution, and a current is generated.

  9. Reserve, flowing electrolyte, high rate lithium battery

    NASA Astrophysics Data System (ADS)

    Puskar, M.; Harris, P.

    Flowing electrolyte Li/SOCl2 tests in single cell and multicell bipolar fixtures have been conducted, and measurements are presented for electrolyte flow rates, inlet and outlet temperatures, fixture temperatures at several points, and the pressure drop across the fixture. Reserve lithium batteries with flowing thionyl-chloride electrolytes are found to be capable of very high energy densities with usable voltages and capacities at current densities as high as 500 mA/sq cm. At this current density, a battery stack 10 inches in diameter is shown to produce over 60 kW of power while maintaining a safe operating temperature.

  10. Magnetohydrodynamic liquid-metal flows in a rectangular channel with an axial magnetic field, a moving conducting wall and free surfaces

    NASA Astrophysics Data System (ADS)

    Talmage, Gita; Walker, John S.; Brown, Samuel H.; Sondergaard, Neal A.; Burt, Patricia E.

    1990-11-01

    Fully developed, viscous liquid-metal velocity profiles and induced magnetic field contours were studied for Hartmann numbers of M=2 and 10 and for different load currents for a particular rectangular channel configuration (two-dimensional Couette flow). The rectangular channel was assumed to have a homogeneous external (axial) magnetic field parallel to the moving, perfectly conducting top wall and the stationary, perfectly conducting bottom wall. The two stationary side walls were also perfect conductors. The small gap between the moving wall and each side wall was an insulating, free surface. The method of weighted residuals was used to obtain truncated series solutions for the variables of interest. The heavy load currents across the channel were obtained by simulating an external potential to the conducting moving wall. The load currents in each case were opposed by the induced electric field. Since there is no pressure gradient, the flow along the channel is driven by the viscous effects of the moving wall and the Lorentz body force and is retarded by the stationary walls. In the case where no load current is applied across the channel, the current circulates in the channel. The circulation is driven by the generator that is due to the axial variation of velocity in an axial magnetic field. The numerical results presented show that the radial gap and the free surface region represent electrical resistances in parallel between the perfectly conducting stationary wall and the perfectly conducting moving wall. The numerical results also show that the resistance of the radial gap increases as M2 while that of the free surface increases by M or M1/2. Thus, as M increases, the division of current shifts to the free surface region and the current density in the radial gap decreases as M-1. The theoretical magnetohydrodynamic model presented here was developed to provide numerical parameters to help in the design of liquid-metal current collectors. Numerical results

  11. Lithium-Polysulfide Flow Battery Demonstration

    ScienceCinema

    Zheng, Wesley

    2014-07-16

    In this video, Stanford graduate student Wesley Zheng demonstrates the new low-cost, long-lived flow battery he helped create. The researchers created this miniature system using simple glassware. Adding a lithium polysulfide solution to the flask immediately produces electricity that lights an LED. A utility version of the new battery would be scaled up to store many megawatt-hours of energy.

  12. Lithium-Polysulfide Flow Battery Demonstration

    SciTech Connect

    Zheng, Wesley

    2014-06-30

    In this video, Stanford graduate student Wesley Zheng demonstrates the new low-cost, long-lived flow battery he helped create. The researchers created this miniature system using simple glassware. Adding a lithium polysulfide solution to the flask immediately produces electricity that lights an LED. A utility version of the new battery would be scaled up to store many megawatt-hours of energy.

  13. On the effect of standard PFEM remeshing on volume conservation in free-surface fluid flow problems

    NASA Astrophysics Data System (ADS)

    Franci, Alessandro; Cremonesi, Massimiliano

    2016-07-01

    The aim of this work is to analyze the remeshing procedure used in the particle finite element method (PFEM) and to investigate how this operation may affect the numerical results. The PFEM remeshing algorithm combines the Delaunay triangulation and the Alpha Shape method to guarantee a good quality of the Lagrangian mesh also in large deformation processes. However, this strategy may lead to local variations of the topology that may cause an artificial change of the global volume. The issue of volume conservation is here studied in detail. An accurate description of all the situations that may induce a volume variation during the PFEM regeneration of the mesh is provided. Moreover, the crucial role of the parameter α used in the Alpha Shape method is highlighted and a range of values of α for which the differences between the numerical results are negligible, is found. Furthermore, it is shown that the variation of volume induced by the remeshing reduces by refining the mesh. This check of convergence is of paramount importance for the reliability of the PFEM. The study is carried out for 2D free-surface fluid dynamics problems, however the conclusions can be extended to 3D and to all those problems characterized by significant variations of internal and external boundaries.

  14. Magnetohydrodynamic liquid-metal flows in a rectangular channel with an axial magnetic field, a moving conducting wall, and free surfaces

    NASA Astrophysics Data System (ADS)

    Talmage, Gita; Walker, John S.; Brown, Samuel H.; Sondergaard, Neal A.; Burt, Patricia E.

    1989-11-01

    Fully developed, viscous liquid-metal velocity profiles and induced magnetic field contours were studied for Hartmann number of M=2 and 10 and for different load currents for a particular rectangular channel configuration (two-dimensional Couette flow). The rectangular channel was assumed to have a homogeneous external (axial) magnetic field parallel to the moving, perfectly conducting top wall and the stationary, perfectly conducting bottom wall. The two stationary side walls were also perfect conductors. The small gap between the moving wall and each side wall was an insulating, free surface. The method of weighted residuals was used to obtain truncated series solutions for the variables of interest. The heavy load currents across the channel were obtained by simulating an external potential to the conducting moving wall. The load currents in each case were opposed by the induced electric field. Since there is no pressure gradient, the flow along the channel is driven by the viscous effects of the moving wall and the Lorentz body force and is retarded by the stationary walls. The circulation is driven by the generator that is due to the axial variation of velocity in an axial magnetic field. The numerical data presented show that the radial gap and the free surface region represent electrical resistances in parallel between the perfectly conducting stationary wall and the perfectly conducting moving wall.

  15. Study on Free Surface and Channel Flow Induced by Low-Temperature Plasma via Lattice Boltzmann Method

    NASA Astrophysics Data System (ADS)

    Wan, Gang; Jin, Yong; Li, Haiyuan; Li, Baoming

    2016-03-01

    Active boundary layer flow control and boundary layer manipulation in the channel flow that was based on low temperature plasma were studied by means of a lattice Boltzmann method. Two plasma actuators were placed in a row to obtain the influence rule of their separation distance on the velocity profile at three locations and maximum velocity in the flow field. Two plasma actuators were placed symmetrically inside a channel to examine the effect of channel height and voltage on the velocity profile and flow rate. It was found that the channel height controls the distribution of flow velocity, which affected the flow rate and its direction. Increasing plasma voltage had a negative effect on the flow rate due to the generation of a larger and stronger flow vortex.

  16. Free-surface wave-induced separation

    SciTech Connect

    Zhang, Z.J.; Stern, F.

    1996-09-01

    Free-surface wave-induced separation is studied for a surface-piercing NACA 0024 foil over a range of Froude numbers (0, .2, .37, .55) through computational fluid dynamics of the unsteady Reynolds-averaged Navier-Stokes and the continuity equations with the Baldwin-Lomax turbulence model, exact nonlinear kinematic and approximate dynamic free-surface boundary conditions, and a body/free-surface conforming grid. The flow conditions and uncertainty analysis are discussed. A topological rule for a surface-piercing body is derived and verified. Steady-flow results are presented and analyzed with regard to the wave and viscous flow and the nature of the separation.

  17. Numerical investigation of oscillatory thermocapillary flows under zero gravity in a circular liquid film with concave free surfaces

    NASA Astrophysics Data System (ADS)

    Yamamoto, T.; Takagi, Y.; Okano, Y.; Dost, S.

    2016-03-01

    NASA astronaut Pettit has conducted thermocapillary flow experiments in water films suspended in a solid ring onboard the International Space Station (ISS) in 2003 and 2011. In one of these experiments, an oscillatory thermocapillary flow was observed. The developed flow broke its symmetry along the centerline of the film. To the best of our knowledge, there are no studies on such oscillatory thermocapillary flows in thin films, and the flow-mechanism giving rise to such oscillatory flows is also not well understood. In order to shed light on the subject, we have carried out a numerical simulation study. The simulation results have shown that the water film geometry (film surface shape; being concave) is an important parameter and give rise to three oscillatory flow structures in the film, namely, a hydrothermal wave developing near the heated section, a symmetric oscillatory flow due to temperature variations, and a symmetry breaking flow due to the hydrodynamic instability along the free boundary layer (mixing layer) and the development of the hydrothermal waves. Simulation results show that the symmetry-breaking phenomenon observed in the thin film experiment on the ISS can be explained by the hydrodynamic instability and the development of hydrothermal waves.

  18. Lithium mass flow control for high power Lorentz Force Accelerators

    NASA Astrophysics Data System (ADS)

    Kodys, Andrea D.; Emsellem, Gregory; Cassady, Leonard D.; Polk, James E.; Choueiri, Edgar Y.

    2001-02-01

    A lithium feeding system has been developed to measure and control propellant flow for 30-200 kW Lithium Lorentz Force Accelerators (LiLFAs). The new, mechanically actuated, liquid lithium feed system has been designed and tested as a central component of a campaign to obtain basic data and establish scaling laws and performance relations for these thrusters. Calibration data are presented which demonstrate reliable and controllable feed of liquid lithium to the vaporizer hollow cathode of the thruster at flow rates between 10 and 120 mg/s. The ability to thermally track the liquid lithium through the system by the use of external temperature measurements is demonstrated. In addition, recent developments are presented in the establishment and successful testing of a lithium handling facility and safety procedures allowing for the in-house loading of the feed system and the neutralization, cleaning and disposal of up to 300 g of lithium. .

  19. Computational and theoretical analysis of free surface flow in a thin liquid film under zero and normal gravity

    NASA Technical Reports Server (NTRS)

    Faghri, Amir; Swanson, Theodore D.

    1988-01-01

    The results of a numerical computation and theoretical analysis are presented for the flow of a thin liquid film in the presence and absence of a gravitational body force. Five different flow systems were used. Also presented are the governing equations and boundary conditions for the situation of a thin liquid emanating from a pressure vessel; traveling along a horizontal plate with a constant initial height and uniform initial velocity; and traveling radially along a horizontal disk with a constant initial height and uniform initial velocity.

  20. A low diffusive Lagrange-remap scheme for the simulation of violent ai-water free-surface flows

    NASA Astrophysics Data System (ADS)

    Bernard-Champmartin, Aude; De Vuyst, Florian

    2014-10-01

    In 2002, Després and Lagoutière [17] proposed a low-diffusive advection scheme for pure transport equation problems, which is particularly accurate for step-shaped solutions, and thus suited for interface tracking procedure by a color function. This has been extended by Kokh and Lagoutière [28] in the context of compressible multifluid flows using a five-equation model. In this paper, we explore a simplified variant approach for gas-liquid three-equation models. The Eulerian numerical scheme has two ingredients: a robust remapped Lagrange solver for the solution of the volume-averaged equations, and a low diffusive compressive scheme for the advection of the gas mass fraction. Numerical experiments show the performance of the computational approach on various flow reference problems: dam break, sloshing of a tank filled with water, wate-water impact and finally a case of Rayleigh-Taylor instability. One of the advantages of the present interface capturing solver is its natural implementation on parallel processors or computers. wave formation and wave breaking; wall wave impacts, local pressure peaks and pressure loadings; formation of air pockets; ejection, fragmentation of liquid droplets; Archimedes buoyancy effect with rising of bubbles and fall of droplets; effects of gas compressibility inducing a gas-to-liquid response by a pressure wave, etc. In this paper, we consider immiscible gas-liquid two-phase flow problems. The strong ratio of mass density between gas and liquid (typically 1:1000) is known to be a source of numerical stiffness and numerical instability. Therefore robust computational approaches supporting high density ratio have to be considered. Among the family of conservative Finite Volume methods (FVM), the Lagrange-remapped solvers (see e.g. [42,45,6,4,25,2]) provide both robustness and stability with achievement of mathematical properties of positiveness and entropy compatibility.Lagrange-remap numerical schemes (also referred to as Eule

  1. A low diffusive Lagrange-remap scheme for the simulation of violent ai-water free-surface flows

    NASA Astrophysics Data System (ADS)

    Bernard-Champmartin, Aude; De Vuyst, Florian

    2014-10-01

    In 2002, Després and Lagoutière [17] proposed a low-diffusive advection scheme for pure transport equation problems, which is particularly accurate for step-shaped solutions, and thus suited for interface tracking procedure by a color function. This has been extended by Kokh and Lagoutière [28] in the context of compressible multifluid flows using a five-equation model. In this paper, we explore a simplified variant approach for gas-liquid three-equation models. The Eulerian numerical scheme has two ingredients: a robust remapped Lagrange solver for the solution of the volume-averaged equations, and a low diffusive compressive scheme for the advection of the gas mass fraction. Numerical experiments show the performance of the computational approach on various flow reference problems: dam break, sloshing of a tank filled with water, wate-water impact and finally a case of Rayleigh-Taylor instability. One of the advantages of the present interface capturing solver is its natural implementation on parallel processors or computers. wave formation and wave breaking; wall wave impacts, local pressure peaks and pressure loadings; formation of air pockets; ejection, fragmentation of liquid droplets; Archimedes buoyancy effect with rising of bubbles and fall of droplets; effects of gas compressibility inducing a gas-to-liquid response by a pressure wave, etc. In this paper, we consider immiscible gas-liquid two-phase flow problems. The strong ratio of mass density between gas and liquid (typically 1:1000) is known to be a source of numerical stiffness and numerical instability. Therefore robust computational approaches supporting high density ratio have to be considered. Among the family of conservative Finite Volume methods (FVM), the Lagrange-remapped solvers (see e.g. [42,45,6,4,25,2]) provide both robustness and stability with achievement of mathematical properties of positiveness and entropy compatibility.Lagrange-remap numerical schemes (also referred to as Eule

  2. Free surface calculations in mantle convection

    NASA Astrophysics Data System (ADS)

    Rose, I.; Buffett, B. A.; Heister, T.

    2015-12-01

    Geodynamic simulations increasingly rely on simulations with a true free surface to investigate questions of dynamic topography, tectonic deformation, gravity perturbations, and global mantle convection. However, implementations of free surface boundary conditions have proven challenging from a standpoint of accuracy, robustness, and stability. In particular, free surfaces tend to suffer from sloshing instabilities, also known as the "drunken sailor" instability, which severely limit time step sizes. Several schemes have been proposed in the literature to deal with these instabilities. Here we analyze the problem of creeping viscous flow with a free surface and discuss the origin of these instabilities. We demonstrate their cause and how existing stabilization schemes work to damp them out. Our analysis is based on formulating a generalized eigenvalue problem for the relaxation spectra of the linearized free surface problem. We also propose a new scheme for removing instabilites from free surface calculations. It does not require modifications to the system matrix, nor additional variables, but is instead an explicit scheme based on nonstandard finite differences. It relies on a single stabilization parameter which may be identified with the smallest relaxation timescale of the free surface. We analyze the stability and accuracy of the nonstandard finite difference scheme, and describe its implementation in the open source mantle convection software Aspect. We also provide comparisons between the nonstandard finite difference scheme and the quasi-implicit scheme proposed by Kaus, Muhlhaus, and May (2010).

  3. Fluid Dynamics with Free Surfaces

    Energy Science and Technology Software Center (ESTSC)

    1992-02-01

    RIPPLE is a two-dimensional, transient, free surface incompressible fluid dynamics program. It allows multiple free surfaces with surface tension and wall adhesion forces and has a partial cell treatment which allows curved boundaries and interior obstacles.

  4. Implicit solution of Stokes flow equation with material transport: toward thermal convection simulation under the self-gravitating field with free surface

    NASA Astrophysics Data System (ADS)

    Furuichi, M.; Nakagawa, T.; May, D.

    2013-12-01

    Stabilizing a numerical oscillation in free surface treatment is chagrining topic for a geodynamics simulation [e.g. Kaus et al. 2010, Duretz et al., 2011]. It is especially important for the Stokes flow simulation under the self-gravitating field based on 'Spherical Cartesian' method [Gerya et al., 2007], which is useful for simulating a long time scale dynamics of sinking metal rich materials to construct planetary core. The conventional explicit time stepping algorithm, which solves Stokes flow equation for a given material distribution at a previous time step, however has a difficulty for simulating dynamics such as a thermal convection, after the construction of layered structure in the planetary interior because of numerical oscillation. One effective approach for such numerically problematic behavior is an implicit treatment of advection term. In this study, three types of implicit strategy are discussed. First is the full implicit treatment with iterative non-linear solver which uses transported density by maker-in-cell method as nonlinear update. The maker-in-cell method is commonly used as low diffusive advection method, but is computationally expensive with makers to mesh interpolation. Second approach uses semi-Lagrangian method for nonlinear update instead of the maker-in-cell method to reduce computational cost. Third approach is to solve the Stokes flow equation combined with the linearized advection term in central-difference discretization to avoid the nonlinear update by the transport. In the second and third algorithms, physical value at the next time step is still transported by low diffusive maker-in-cell method. These three types of implicit method are examined by numerical experiment.

  5. Modelling the transition between fixed and mobile bed conditions in two-phase free-surface flows: The Composite Riemann Problem and its numerical solution

    NASA Astrophysics Data System (ADS)

    Rosatti, Giorgio; Zugliani, Daniel

    2015-03-01

    In a two-phase free-surface flow, the transition from a mobile-bed condition to a fixed-bed one (and vice versa) occurs at a sharp interface across which the relevant system of partial differential equations changes abruptly. This leads to the possibility of conceiving a new type of Riemann Problem (RP), which we have called Composite Riemann Problem (CRP), where not only the initial constant values of the variables but also the system of equations change from left to right of a discontinuity. In this paper, we present a strategy for solving a CRP by reducing it to a standard RP of a single, composite system of equations. This can be obtained by combining the two original systems by means of a suitable weighting function, namely the erodibility variable, and the introduction of an appropriate differential equation for this quantity. In this way, the CRP problem can be analyzed theoretically with standard methods, and the features of the solutions can be clearly identified. In particular, a stationary contact wave is able to correctly describe the sharp transition between mobile- and fixed-bed conditions. A finite volume scheme based on the Multiple Averages Generalized Roe approach (Rosatti and Begnudelli (2013) [22]) was used to numerically solve the fixed-mobile CRP. Several test cases demonstrate the effectiveness, exact well balanceness and high accuracy of the scheme when applied to problems that fall within the physical range of applicability of the relevant mathematical model.

  6. Scale separation for multi-scale modeling of free-surface and two-phase flows with the conservative sharp interface method

    SciTech Connect

    Han, L.H. Hu, X.Y. Adams, N.A.

    2015-01-01

    In this paper we present a scale separation approach for multi-scale modeling of free-surface and two-phase flows with complex interface evolution. By performing a stimulus-response operation on the level-set function representing the interface, separation of resolvable and non-resolvable interface scales is achieved efficiently. Uniform positive and negative shifts of the level-set function are used to determine non-resolvable interface structures. Non-resolved interface structures are separated from the resolved ones and can be treated by a mixing model or a Lagrangian-particle model in order to preserve mass. Resolved interface structures are treated by the conservative sharp-interface model. Since the proposed scale separation approach does not rely on topological information, unlike in previous work, it can be implemented in a straightforward fashion into a given level set based interface model. A number of two- and three-dimensional numerical tests demonstrate that the proposed method is able to cope with complex interface variations accurately and significantly increases robustness against underresolved interface structures.

  7. A free surface sharpening strategy using optimization method

    NASA Astrophysics Data System (ADS)

    Song, Hongchao; Ji, Lucheng; Tu, Shuangzhang

    2015-11-01

    VOF method which consists in transporting a discontinuous marker variable is widely used to capture the free surface in computational fluid dynamics. There is numerical dissipation in simulations involving the transport of the marker. Numerical dissipation makes the free surface lose its physical nature. A free surface sharpening strategy based on optimization method is presented in the paper. The strategy can keep the location of the free surface and local mass conservation at both time, and can also keep free surface in a constant width. It is independent on the types of solvers and meshes. Two famous cases were chosen for verifying the free surface sharpening strategy performance. Results show that the strategy has a very good performance on keeping local mass conservation. The efficiency of prediction of the free surface is improved by applying the strategy. Accurate modeling of flow details such as drops can also be captured by this method.

  8. Free surface mixing with heat transfer

    SciTech Connect

    Raad, P.E.; Fadda, D.

    1997-05-23

    This study investigates the thermal mixing phenomenon as external rocking excitations are applied to a container partially filled with a thermally nonhomogeneous fluid. The aim of this work is to determine the effects of the rocking frequency on thermal mixing in free surface flows. Numerical results show that optimum mixing is achieved while rocking at the wave natural frequency of the tank where the free surface displacements are greatest. At this optimal frequency the strong mixing is observed to be highly concentrated in the area near the free surface. The interest is motivated by the desire to understand the fundamental physics as well as by the importance of current engineering applications in fields such as solar energy (collectors), environmental engineering (ponds, estuaries) aerospace (fuel tanks), electronics (thermal management), manufacturing (sand casting), and air conditioning (residential enclosures).

  9. Simulation of Nematic Free Surfaces

    NASA Astrophysics Data System (ADS)

    de Miguel, Enrique; Martín del Río, Elvira

    Molecular dynamics and Monte Carlo methods are applied to study the liquid free surfaces in model liquid crystals. The simulation results suggest that the attractive interactions promote parallel alignment of the molecules at the nematic free surface in the Gay-Berne model, in agreement with theoretical predictions. A change in the orientation from planar to homeotropic is observed and explained in terms of a competing effect between attractive and repulsive interactions. Finally, the simulation results give clear evidence that the hard-core repulsions favor homeotropic orientation at the nematic free surface, in agreement with most theories.

  10. Effect of Energetic Plasma Flux on Flowing Liquid Lithium Surfaces

    NASA Astrophysics Data System (ADS)

    Kalathiparambil, Kishor; Jung, Soonwook; Christenson, Michael; Fiflis, Peter; Xu, Wenyu; Szott, Mathew; Ruzic, David

    2014-10-01

    An operational liquid lithium system with steady state flow driven by thermo-electric magneto-hydrodynamic force and capable of constantly refreshing the plasma exposed surface have been demonstrated at U of I. To evaluate the system performance in reactor relevant conditions, specifically to understand the effect of disruptive plasma events on the performance of the liquid metal PFCs, the setup was integrated to a pulsed plasma generator. A coaxial plasma generator drives the plasma towards a theta pinch which preferentially heats the ions, simulating ELM like flux, and the plasma is further guided towards the target chamber which houses the flowing lithium system. The effect of the incident flux is examined using diagnostic tools including triple Langmuir probe, calorimeter, rogowski coils, Ion energy analyzers, and fast frame spectral image acquisition with specific optical filters. The plasma have been well characterized and a density of ~1021 m-3, with electron temperature ~10 - 20 eV is measured, and final plasma velocities of 34 - 74 kms-1 have been observed. Calorimetric measurements using planar molybdenum targets indicate a maximum plasma energy (with 6 kV plasma gun and 20 kV theta pinch) of 0.08 MJm-2 with plasma divergence effects resulting in marginal reduction of 40 +/- 23 J in plasma energy. Further results from the other diagnostic tools, using the flowing lithium targets and the planar targets coated with lithium will be presented. DOE DE-SC0008587.

  11. Coupling a local adaptive grid refinement technique with an interface sharpening scheme for the simulation of two-phase flow and free-surface flows using VOF methodology

    NASA Astrophysics Data System (ADS)

    Malgarinos, Ilias; Nikolopoulos, Nikolaos; Gavaises, Manolis

    2015-11-01

    This study presents the implementation of an interface sharpening scheme on the basis of the Volume of Fluid (VOF) method, as well as its application in a number of theoretical and real cases usually modelled in literature. More specifically, the solution of an additional sharpening equation along with the standard VOF model equations is proposed, offering the advantage of "restraining" interface numerical diffusion, while also keeping a quite smooth induced velocity field around the interface. This sharpening equation is solved right after volume fraction advection; however a novel method for its coupling with the momentum equation has been applied in order to save computational time. The advantages of the proposed sharpening scheme lie on the facts that a) it is mass conservative thus its application does not have a negative impact on one of the most important benefits of VOF method and b) it can be used in coarser grids as now the suppression of the numerical diffusion is grid independent. The coupling of the solved equation with an adaptive local grid refinement technique is used for further decrease of computational time, while keeping high levels of accuracy at the area of maximum interest (interface). The numerical algorithm is initially tested against two theoretical benchmark cases for interface tracking methodologies followed by its validation for the case of a free-falling water droplet accelerated by gravity, as well as the normal liquid droplet impingement onto a flat substrate. Results indicate that the coupling of the interface sharpening equation with the HRIC discretization scheme used for volume fraction flux term, not only decreases the interface numerical diffusion, but also allows the induced velocity field to be less perturbed owed to spurious velocities across the liquid-gas interface. With the use of the proposed algorithmic flow path, coarser grids can replace finer ones at the slight expense of accuracy.

  12. Free surface dynamics of nematic liquid crystal

    NASA Astrophysics Data System (ADS)

    Cummings, Linda; Kondic, Lou; Lam, Michael; Lin, Te-Sheng

    2014-11-01

    Spreading thin films of nematic liquid crystal (NLC) are known to behave very differently to those of isotropic fluids. The polar interactions of the rod-like molecules with each other, and the interactions with the underlying substrate, can lead to intricate patterns and instabilities that are not yet fully understood. The physics of a system even as simple as a film of NLC spreading slowly over a surface (inclined or horizontal) are remarkably complex: the outcome depends strongly on the details of the NLC's behavior at both the substrate and the free surface (so-called ``anchoring'' effects). We will present a dynamic flow model that takes careful account of such nematic-substrate and nematic-free surface interactions. We will present model simulations for several different flow scenarios that indicate the variety of behavior that can emerge. Spreading over a horizontal substrate may exhibit a range of unstable behavior. Flow down an incline also exhibits intriguing instabilities: in addition to the usual transverse fingering, instabilities can be manifested behind the flowing front in a manner reminiscent of Newtonian flow down an inverted substrate. NSF DMS-1211713.

  13. Two-Dimensional Optical Measurement of Waves on Liquid Lithium Jet Simulating IFMIF Target Flow

    SciTech Connect

    Kazuhiro Itoh; Hiroyuki Koterazawa; Taro Itoh; Yutaka Kukita; Hiroo Kondo; Nobuo Yamaoka; Hiroshi Horiike; Mizuho Ida; Hideo Nakamura; Hiroo Nakamura; Takeo Muroga

    2006-07-01

    Waves on a liquid-lithium jet flow, simulating a proposed high-energy beam target design, have been measured using an optical technique based on specular reflection of a single laser beam on the jet surface. The stream-wise and spanwise fluctuations of the local free-surface slope were least-square fitted with a sinusoidal curve to makeup the signals lost due to the constriction in the optical arrangement. The waveform was estimated with an assumption that wave phase speed can be calculated using the dispersion relation for linear capillary-gravity waves. The direction of propagation on the jet surface was also evaluated so that the wave amplitudes, calculated by integral of slope angle signal, agree consistently in stream-wise and spanwise direction. These measurements and analyses show that the waves at the measurement location for a jet velocity of 1.2 m/s can best be represented by oblique waves with an inclination of 1.23 rad, a wavelength of 3.8 mm and a wave amplitude of about 0.05 mm. (authors)

  14. Lithium

    USGS Publications Warehouse

    Jaskula, B.W.

    2011-01-01

    In 2010, lithium consumption in the United States was estimated to have been about 1 kt (1,100 st) of contained lithium, a 23-percent decrease from 2009. The United States was estimated to be the fourth largest consumer of lithium. It remained the leading importer of lithium carbonate and the leading producer of value-added lithium materials. Only one company, Chemetall Foote Corp. (a subsidiary of Chemetall GmbH of Germany), produced lithium compounds from domestic resources. In 2010, world lithium consumption was estimated to have been about 21 kt (22,000 st) of lithium contained in minerals and compounds, a 12-percent increase from 2009.

  15. Lithium

    USGS Publications Warehouse

    Jaskula, B.W.

    2010-01-01

    In 2009, lithium consumption in the United States was estimated to have been about 1.2 kt (1,300 st) of contained lithium, a 40-percent decrease from 2008. The United States was estimated to be the fourth largest consumer of lithium, and remained the leading importer of lithium carbonate and the leading producer of value-added lithium materials. Only one company, Chemetall Foote Corp. (a subsidiary of Chemetall GmbH of Germany), produced lithium compounds from domestic resources. In 2009, world lithium consumption was estimated to have been about 18.7 kt (20,600 st) of lithium contained in minerals and compounds.

  16. 2D dry granular free-surface flow over complex topography with obstacles. Part I: experimental study using a consumer-grade RGB-D sensor

    NASA Astrophysics Data System (ADS)

    Caviedes-Voullième, Daniel; Juez, Carmelo; Murillo, Javier; García-Navarro, Pilar

    2014-12-01

    Avalanches, debris flows and other types of gravity-driven granular flows are a common hazard in mountainous regions. These regions often have human settlements in the lower parts of valleys, with human structures dangerously exposed to the destructive effects of these geophysical flows. Therefore a scientific effort has been made to understand, model and simulate geophysical granular flows. In order for computer models and simulations to be of predictive value they need to be validated under controlled, yet nature-like conditions. This work presents an experimental study of granular flow over a simplified mountain slope and valley topography. The experimental facility has a rough bed with very high slope at the upstream end and adverse slope on the downstream end, following a parabolic profile. Obstacles are present in the lower regions. Transient measurements of the moving granular surfaces were taken with a consumer-grade RGB-D sensor, providing transient 2D elevation fields around the obstacles. Three experimental configurations were tested, with semispheres of different diameters and a square dike obstacle. The experimental results are very consistent and repeatable. The quantitative, transient and two-dimensional data for all three experiments constitute excellent benchmarking tests for computational models, such as the one presented in a companion paper.

  17. Lithium

    USGS Publications Warehouse

    Jaskula, B.W.

    2012-01-01

    In 2011, world lithium consumption was estimated to have been about 25 kt (25,000 st) of lithium contained in minerals and compounds, a 10-percent increase from 2010. U.S. consumption was estimated to have been about 2 kt (2,200 st) of contained lithium, a 100-percent increase from 2010. The United States was estimated to be the fourth-ranked consumer of lithium and remained the leading importer of lithium carbonate and the leading producer of value-added lithium materials. One company, Chemetall Foote Corp. (a subsidiary of Chemetall GmbH of Germany), produced lithium compounds from domestic brine resources near Silver Peak, NV.

  18. 2D dry granular free-surface transient flow over complex topography with obstacles. Part II: Numerical predictions of fluid structures and benchmarking

    NASA Astrophysics Data System (ADS)

    Juez, C.; Caviedes-Voullième, D.; Murillo, J.; García-Navarro, P.

    2014-12-01

    Dense granular flows are present in geophysics and in several industrial processes, which has lead to an increasing interest for the knowledge and understanding of the physics which govern their propagation. For this reason, a wide range of laboratory experiments on gravity-driven flows have been carried out during the last two decades. The present work is focused on geomorphological processes and, following previous work, a series of laboratory studies which constitute a further step in mimicking natural phenomena are described and simulated. Three situations are considered with some common properties: a two-dimensional configuration, variable slope of the topography and the presence of obstacles. The setup and measurement technique employed during the development of these experiments are deeply explained in the companion work. The first experiment is based on a single obstacle, the second one is performed against multiple obstacles and the third one studies the influence of a dike on which overtopping occurs. Due to the impact of the flow against the obstacles, fast moving shocks appear, and a variety of secondary waves emerge. In order to delve into the physics of these types of phenomena, a shock-capturing numerical scheme is used to simulate the cases. The suitability of the mathematical models employed in this work has been previously validated. Comparisons between computed and experimental data are presented for the three cases. The computed results show that the numerical tool is able to predict faithfully the overall behavior of this type of complex dense granular flow.

  19. A non-invasive acoustical method to measure the mean roughness height of the free surface of a turbulent shallow water flow.

    PubMed

    Krynkin, A; Horoshenkov, K V; Nichols, A; Tait, S J

    2014-11-01

    In this paper, the directivity of the airborne sound field scattered by a dynamically rough free flow surface in a flume is used to determine the mean roughness height for six hydraulic conditions in which the uniform depth of the turbulent flow. The nonlinear curve fitting method is used to minimize the error between the predicted directivity and directivity data. The data fitting algorithm is based on the averaged solution for the scattered sound pressure as a function of angle which is derived through the Kirchhoff integral and its approximations. This solution takes into account the directivity of the acoustic source. For the adopted source and receiver geometry and acoustic frequency it is shown that the contribution from the stationary phase point (single specular point on the rough surface) yields similar results to those which can be obtained through the full Kirchhoff's integral. The accuracy in the inverted mean roughness height is comparable to that achieved with an array of conductive wave probes. This method enables non-invasive estimation of the flow Reynolds number and uniform flow depth. PMID:25430137

  20. Lithium

    USGS Publications Warehouse

    Ober, J.A.

    2006-01-01

    In 2005, lithium consumption in the United States was at 2.5 kt of contained lithium, nearly 32% more than the estimate for 2004. World consumption was 14.1 kt of lithium contained in minerals and compounds in 2003. Exports from the US increased slightly compared with 2004. Due to strong demand for lithium compounds in 2005, both lithium carbonate plants in Chile were operating at or near capacity.

  1. A study of free-surface electrohydrodynamics

    SciTech Connect

    Kaiser, K.L.

    1989-01-01

    Free-surface electrohydrodynamics (EHD) is a complex phenomena that is difficult to describe, explain, and predict. An analytical and numerical study is performed to assist in the understanding of free-surface EHD. Rayleigh-type critical charge relationships are derived for spherical droplets of perfect and imperfect insulative liquids. Also, mathematical models and a simulator are developed to analyze free-surface EHD in two dimensions. Several configurations are investigated with the simulator. Analytical results indicate that if charge is uniformly dispersed throughout a spherical droplet of perfectly insulating fluid, breakup is possible. If the dielectric constant of the liquid is approximately equal to that of the surrounding air, the charge limit is approximately 10% less than that of a conducting fluid. If ionizable impurities are in the fluid but no transfer of charge occurs between the electrode and the fluid, breakup can still occur. If the liquid's dielectric constant is large, the total charge on the electrode is not much different from the Rayleigh number. A unique donor-cell method was developed to approximate the charge flow equation, properly conserving charge in each cell. A pseudo-surface charge method was also developed. The results were shown to be good for low curvature, simple geometries. Simulation results indicate that the effects of inertia can be substantial in the rise of dielectrophoretic fluid between two electrified plates. The initial stages of the radial breakup of a charged conducting fluid cylinder consisted of wave-like oscillations along the surface. The shape of an insulating jet from a nozzle was seen to be highly dependent on the electric field configuration.

  2. 46 CFR 28.540 - Free surface.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 1 2014-10-01 2014-10-01 false Free surface. 28.540 Section 28.540 Shipping COAST GUARD... Stability § 28.540 Free surface. (a) When doing the stability calculations required by this subpart, the... calculating the following— (1) For each type of consumable liquid, the maximum free surface effect of a...

  3. 46 CFR 28.540 - Free surface.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Free surface. 28.540 Section 28.540 Shipping COAST GUARD... Stability § 28.540 Free surface. (a) When doing the stability calculations required by this subpart, the... calculating the following— (1) For each type of consumable liquid, the maximum free surface effect of a...

  4. 46 CFR 28.540 - Free surface.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Free surface. 28.540 Section 28.540 Shipping COAST GUARD... Stability § 28.540 Free surface. (a) When doing the stability calculations required by this subpart, the... calculating the following— (1) For each type of consumable liquid, the maximum free surface effect of a...

  5. 46 CFR 28.540 - Free surface.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 1 2013-10-01 2013-10-01 false Free surface. 28.540 Section 28.540 Shipping COAST GUARD... Stability § 28.540 Free surface. (a) When doing the stability calculations required by this subpart, the... calculating the following— (1) For each type of consumable liquid, the maximum free surface effect of a...

  6. 46 CFR 28.540 - Free surface.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 1 2012-10-01 2012-10-01 false Free surface. 28.540 Section 28.540 Shipping COAST GUARD... Stability § 28.540 Free surface. (a) When doing the stability calculations required by this subpart, the... calculating the following— (1) For each type of consumable liquid, the maximum free surface effect of a...

  7. Transient shear flow of model lithium lubricating greases

    NASA Astrophysics Data System (ADS)

    Delgado, M. A.; Franco, J. M.; Valencia, C.; Kuhn, E.; Gallegos, C.

    2009-03-01

    This paper deals with the analysis of the transient shear flow behavior of lithium lubricating greases differing in soap concentration and base oil viscosity. The shear-induced evolution of grease microstructure has been studied by means of stress-growth experiments. With this aim, different lubricating grease formulations were manufactured by modifying the concentration of lithium 12-hydroxystearate and the viscosity of the base oil, according to a RSM statistical design. Moreover, atomic force microscopy (AFM) observations were carried out. The transient stress response can be successfully described by the generalized Leider-Bird model based on two exponential terms. Different rheological parameters, related to both the elastic response and the structural breakdown of greases, have been analysed. In this sense, it has been found that the elastic properties of lithium lubricating greases were highly influenced by soap concentration and oil viscosity. The stress overshoot, τ max , depends linearly on both variables in the whole shear rate range studied, although the effect of base oil viscosity on this parameter is opposite at low and high shear rates. Special attention has been given to the first part of the stress-growth curve. In this sense, it can be deduced that the “yielding” energy density not only depends on grease composition, but also on shear rate. Moreover, an interesting asymptotic tendency has been found for both the “yielding” energy density and the stress overshoot by increasing shear rate. The asymptotic values of these parameters have been correlated to the friction coefficient obtained in a ball-disc tribometer.

  8. [Effect of the subsurface constructed wetland evolution into free surface flow constructed wetland on the removal of organic matter, nitrogen, and phosphor in wastewater].

    PubMed

    Wei, Ze-Jun; Xie, Jian-Ping; Huang, Yu-Ming

    2012-11-01

    Many previous studies demonstrated that the performance of the subsurface constructed wetlands (SSCW) for wastewater treatment was superior to that of the free flow surface constructed wetlands (FFSCW). However, our results indicated that the performance of FFSCW derived from the evolution of SSCW due to clogging for COD, TOC, total nitrogen (TN), and total phosphor (TP) removal was higher than those of SSCW with the same substrate and plant. The laboratory culture experiments were adopted to evaluate the effect of the constructed wetland evolution on the organic matter mineralization, nitrification/denitrification as well as removal of nitrogen and phosphor. It was shown that, after evolution of SSCW into FFSCW, the mineralization rate for organic matter (as TOC) was 1.82 mg x h(-1), and it was 1.49 mg x h(-1) for SSCW. The removal efficiency for NO3(-) was 96.8%, and it was 58.1% for SSCW. The abiotic denitrification removal efficiency was 40%, and it was 28.2% for SSCW. In addition, the maximum equilibrium adsorption capacity of the substrate after evolution for phosphor (as P) was 160 mg x kg(-1), and it was 140 mg x kg(-1) for SSCW substrate. The organic coverage of the substrate was found to be beneficial to phosphor removal. The nitrification ability decreased after evolution. These results suggest the important effect of constructed wetland evolution on its performance. PMID:23323410

  9. Lithium

    USGS Publications Warehouse

    Ober, J.

    1998-01-01

    The lithium industry can be divided into two sectors: ore concentrate producers and chemical producers. Ore concentrate producers mine lithium minerals. They beneficiate the ores to produce material for use in ceramics and glass manufacturing.

  10. A numerical procedure for three-dimensional transient free surface seepage

    NASA Astrophysics Data System (ADS)

    Desai, C. S.; Lightner, J. G.; Somasundaram, S.

    A three-dimensional procedure based on the finite element method is proposed for transient free surface seepage. It involves solution of the governing equations by using a time integration scheme. The procedure is applied for solution of confined, and transient free surface flow; the latter includes verification with respect to test results from a laboratory model. It is also applied to free surface flow through a dam with a crack.

  11. Particle accumulation on periodic orbits by repeated free surface collisions

    NASA Astrophysics Data System (ADS)

    Hofmann, Ernst; Kuhlmann, Hendrik C.

    2011-07-01

    The motion of small particles suspended in cylindrical thermocapillary liquid bridges is investigated numerically in order to explain the experimentally observed particle accumulation structures (PAS) in steady two- and time-dependent three-dimensional flows. Particles moving in this flow are modeled as perfect tracers in the bulk, which can undergo collisions with the free surface. By way of free-surface collisions the particles are transferred among different streamlines which represents the particle trajectories in the bulk. The inter-streamline transfer-process near the free surface together with the passive transport through the bulk is used to construct an iterative map that can describe the accumulation process as an attraction to a stable fixed point which represents PAS. The flow topology of the underlying azimuthally traveling hydrothermal wave turns out to be of key importance for the existence of PAS. In a frame of reference exactly rotating with the hydrothermal wave the three-dimensional flow is steady and exhibits co-existing regular and chaotic streamlines. We find that particles are attracted to accumulation structures if a closed regular streamline exists in the rotating frame of reference which closely approaches the free surface locally. Depending on the closed streamline and the particle radius PAS can arise as a specific trajectory which winds about the closed regular streamline or as the surface of a particular stream tube containing the closed streamline.

  12. Numerical evaluation of gas core length in free surface vortices

    NASA Astrophysics Data System (ADS)

    Cristofano, L.; Nobili, M.; Caruso, G.

    2014-11-01

    The formation and evolution of free surface vortices represent an important topic in many hydraulic intakes, since strong whirlpools introduce swirl flow at the intake, and could cause entrainment of floating matters and gas. In particular, gas entrainment phenomena are an important safety issue for Sodium cooled Fast Reactors, because the introduction of gas bubbles within the core causes dangerous reactivity fluctuation. In this paper, a numerical evaluation of the gas core length in free surface vortices is presented, according to two different approaches. In the first one, a prediction method, developed by the Japanese researcher Sakai and his team, has been applied. This method is based on the Burgers vortex model, and it is able to estimate the gas core length of a free surface vortex starting from two parameters calculated with single-phase CFD simulations. The two parameters are the circulation and the downward velocity gradient. The other approach consists in performing a two-phase CFD simulation of a free surface vortex, in order to numerically reproduce the gas- liquid interface deformation. Mapped convergent mesh is used to reduce numerical error and a VOF (Volume Of Fluid) method was selected to track the gas-liquid interface. Two different turbulence models have been tested and analyzed. Experimental measurements of free surface vortices gas core length have been executed, using optical methods, and numerical results have been compared with experimental measurements. The computational domain and the boundary conditions of the CFD simulations were set consistently with the experimental test conditions.

  13. Emission of dimers from a free surface of heated water

    NASA Astrophysics Data System (ADS)

    Bochkarev, A. A.; Polyakova, V. I.

    2014-09-01

    The emission rate of water dimers from a free surface and a wetted solid surface in various cases was calculated by a simplified Monte Carlo method with the use of the binding energy of water molecules. The binding energy of water molecules obtained numerically assuming equilibrium between the free surface of water and vapor in the temperature range of 298-438 K corresponds to the coordination number for liquid water equal to 4.956 and is close to the reference value. The calculation results show that as the water temperature increases, the free surface of water and the wetted solid surface become sources of free water dimers. At a temperature of 438 K, the proportion of dimers in the total flow of water molecules on its surface reaches 1%. It is found that in the film boiling mode, the emission rate of dimers decreases with decreasing saturation vapor. Two mechanisms of the emission are described.

  14. Free surfaces in open capillary channels—Parallel plates

    NASA Astrophysics Data System (ADS)

    Bronowicki, P.; Canfield, P.; Grah, A.; Dreyer, M.

    2015-01-01

    This paper is concerned with forced flow through partially open capillary channels under microgravity conditions. The investigated channel consists of two parallel plates and is bounded by free liquid surfaces along the open sides. The curvature of the channel's gas-liquid interface, which is exposed to the ambient pressure, adjusts to the pressure difference across the interface in accordance with the Young-Laplace equation. Flow within the channel becomes unstable when the free surface collapses and gas ingestion into the flow path occurs—a process that is also referred to as the "choking" phenomenon. During stable flow, the behavior of the free surface is influenced by flow conditions, geometric properties of the channel, and the pre-defined system pressure. In this work, a previously published stability theory is verified for a wide range of model parameters. A detailed study is provided for stable flow in capillary channels, including static and dynamic solutions. The results of the Capillary Channel Flow (CCF) experiment are evaluated and are found to agree well with numerical predictions. A clear limit is determined between stable and unstable flows. It is shown that the model can predict the shape of the free surface under various flow conditions. A numerical tool is employed to exploit the mathematical model, and the general behavior of free surfaces in said capillary channels is studied. Studies are conducted in both viscous and convective flow regimes and in the transition area between the two. The validity of the model is confirmed for a wide range of geometrical configurations and parameters.

  15. Lithium

    MedlinePlus

    ... bipolar disorder (manic-depressive disorder; a disease that causes episodes of depression, episodes of mania, and other abnormal moods). Lithium ... Lithium is also sometimes used to treat depression, schizophrenia (a mental ... emotions), disorders of impulse control (inability to resist the urge ...

  16. Bombardment of thin lithium films with energetic plasma flows

    NASA Astrophysics Data System (ADS)

    Gray, Travis Kelly

    The Divertor Erosion and Vapor Shielding Experiment (DEVEX) has been constructed in the Center for Plasma-Material Interactions at the University of Illinois at Urbana-Champaign. It consists of a conical theta-pinch connected to a 60 kV, 36 muF capacitor bank which is switched with a rise time of 3.5 mus. This results in a peak current of 300 kA for a 30 kV charge on the capacitor bank. The resulting plasma is created and compressed under the theta-pinch coil and then expelled axially towards a target chamber due to the conical taper of the theta-coil. The plasma that reaches the target chamber is dense, 1021 m-3 and cool, 10--20 eV. For the purposes of this study, a thin stainless steel target, sputter coated with a lithium magnetron is the target/material of interest. Both computational [A. Hassanein, Fus. Eng. Des. 60: 527546 (2002)] and experimental [M.L. Apicella, et al., J. Nuc. Mater. 386--388:821823 (2009)] studies have shown that lithium, under fusion relevant plasma bombardment, maintains a much lower surface temperature than other plasma facing materials such as tungsten or carbon. This is believed clue to the strong evaporation and/or sputtering of lithium under these conditions. Subsequently a vapor cloud is formed in front of the plasma-facing surface. The lithium vapor interacts with the incident plasma stream absorbing a fraction of the incident plasma energy via the lithium-plasma interactions. Here, we present experimental verification of substantially reduced target surface temperature with the use of thin lithium films on surface of the target as compared to a bare target. Furthermore, optical measurements are made to determine the density and temperature of the lithium vapor cloud as it expands away from the target surface. A collisional-radiative model for both neutrals and singly ionized lithium is used to model the lithium vapor and is found to correlate well with the optical measurements. The vapor cloud electron temperature is found to

  17. Glassy Dynamics Altered by a Free Surface

    NASA Astrophysics Data System (ADS)

    Tsui, Ophelia

    Studies of polymer dynamics in thin films showed that a highly mobile region exists at the free surface of most if not all polymers. In this talk, I shall review some of these observations, with highlights given to the recent findings that chain flexibility and connectivity may on occasions be necessary for the free surface to exercise its influence. Afterward, I shall ponder on how the influence of the free surface may penetrate as far as several polymer radii of gyration into the inner region, as found both in experiments and simulations. Near the glass transition temperature, our MD simulations showed that the dynamics consist mainly of string-like particle hopping motions, as found by others. Importantly, as the temperature decreases, the hopping motions become increasingly repetitive and back-and-forth, contributing no structural relaxations. We propose that structural relaxations are then brought about by pair-interactions between strings. Near the free surface, however, similar repetitive hopping motions are only observed sufficiently far removed from the free surface. We propose that the free surface induces a penetrating surface mobile region by breaking the memory in the particle dynamics. A possible mechanism based on string interactions will be discussed. We are grateful to the support of NSF through Project DMR-1310536 and Hong Kong GRF Grant 15301014.

  18. A finite difference model for free surface gravity drainage

    SciTech Connect

    Couri, F.R.; Ramey, H.J. Jr.

    1993-09-01

    The unconfined gravity flow of liquid with a free surface into a well is a classical well test problem which has not been well understood by either hydrologists or petroleum engineers. Paradigms have led many authors to treat an incompressible flow as compressible flow to justify the delayed yield behavior of a time-drawdown test. A finite-difference model has been developed to simulate the free surface gravity flow of an unconfined single phase, infinitely large reservoir into a well. The model was verified with experimental results in sandbox models in the literature and with classical methods applied to observation wells in the Groundwater literature. The simulator response was also compared with analytical Theis (1935) and Ramey et al. (1989) approaches for wellbore pressure at late producing times. The seepage face in the sandface and the delayed yield behavior were reproduced by the model considering a small liquid compressibility and incompressible porous medium. The potential buildup (recovery) simulated by the model evidenced a different- phenomenon from the drawdown, contrary to statements found in the Groundwater literature. Graphs of buildup potential vs time, buildup seepage face length vs time, and free surface head and sand bottom head radial profiles evidenced that the liquid refills the desaturating cone as a flat moving surface. The late time pseudo radial behavior was only approached after exaggerated long times.

  19. Heat transfer to a thin liquid film with a free surface

    NASA Technical Reports Server (NTRS)

    Rahman, M. M.; Faghri, A.; Hankey, W. L.; Swanson, T. D.

    1989-01-01

    The numerically computed flow field and heat transfer coefficient are presented for the free surface flow of a thin liquid film in the presence or absence of a gravitational body force. The results of an approximate analysis using the Pohlhausen integral method is also discussed. The flow systems studied here include both plane and radial film flows in the presence or absence of a gravitational body force. The heating conditions include isothermal and uniformly heated surfaces. The transport conditions considered at the free surface are an adiabatic condition and an evaporative free surface maintained at its saturation temperature. The height of the free surface, flow field and heat transfer coefficient, were found to be strongly affected by the gravitational body force. They were also found to depend on the Reynolds number and Froude number of the incoming fluid. In the presence of gravity, a hydraulic jump was found to occur under some flow conditions.

  20. Sulphur-impregnated flow cathode to enable high-energy-density lithium flow batteries.

    PubMed

    Chen, Hongning; Zou, Qingli; Liang, Zhuojian; Liu, Hao; Li, Quan; Lu, Yi-Chun

    2015-01-01

    Redox flow batteries are promising technologies for large-scale electricity storage, but have been suffering from low energy density and low volumetric capacity. Here we report a flow cathode that exploits highly concentrated sulphur-impregnated carbon composite, to achieve a catholyte volumetric capacity 294 Ah l(-1) with long cycle life (>100 cycles), high columbic efficiency (>90%, 100 cycles) and high energy efficiency (>80%, 100 cycles). The demonstrated catholyte volumetric capacity is five times higher than the all-vanadium flow batteries (60 Ah l(-1)) and 3-6 times higher than the demonstrated lithium-polysulphide approaches (50-117 Ah l(-1)). Pseudo-in situ impedance and microscopy characterizations reveal superior electrochemical and morphological reversibility of the sulphur redox reactions. Our approach of exploiting sulphur-impregnated carbon composite in the flow cathode creates effective interfaces between the insulating sulphur and conductive carbon-percolating network and offers a promising direction to develop high-energy-density flow batteries. PMID:25565112

  1. Sulphur-impregnated flow cathode to enable high-energy-density lithium flow batteries

    NASA Astrophysics Data System (ADS)

    Chen, Hongning; Zou, Qingli; Liang, Zhuojian; Liu, Hao; Li, Quan; Lu, Yi-Chun

    2015-01-01

    Redox flow batteries are promising technologies for large-scale electricity storage, but have been suffering from low energy density and low volumetric capacity. Here we report a flow cathode that exploits highly concentrated sulphur-impregnated carbon composite, to achieve a catholyte volumetric capacity 294 Ah l-1 with long cycle life (>100 cycles), high columbic efficiency (>90%, 100 cycles) and high energy efficiency (>80%, 100 cycles). The demonstrated catholyte volumetric capacity is five times higher than the all-vanadium flow batteries (60 Ah l-1) and 3-6 times higher than the demonstrated lithium-polysulphide approaches (50-117 Ah l-1). Pseudo-in situ impedance and microscopy characterizations reveal superior electrochemical and morphological reversibility of the sulphur redox reactions. Our approach of exploiting sulphur-impregnated carbon composite in the flow cathode creates effective interfaces between the insulating sulphur and conductive carbon-percolating network and offers a promising direction to develop high-energy-density flow batteries.

  2. Flow Boiling Heat Transfer to Lithium Bromide Aqueous Solution in Subcooled Region

    NASA Astrophysics Data System (ADS)

    Furukawa, Masahiro; Kaji, Masao; Nishizumi, Takeharu; Ozaki, Shinji; Sekoguchi, Kotohiko

    To improve the thermal performance of high temperature generator of absorption chiller/heater, heat transfer characteristics of flow boiling of lithium bromide aqueous solution in the subcooled region were experimentally investigated. Experiments were made for water and lithium bromide aqueous solution flowing in a rectangular channel (5 mm × 20 mm cross section) with one side wall heated. Boiling onset quality of lithium bromide aqueous solution is greater than that of water. The heat transfer coefficient of lithium bromide aqueous solution is about a half of that of water under the same experimental conditions of inlet velocity and heat flux. The experimental data of heat transfer coefficient for water are compared with the empirical correlation of Thom et al.11) and a fairly good agreement is obtained. The predictive calculations by the method of Sekoguchi et al.12) are compared with the data for water and lithium bromide aqueous solution. Agreement between them is good for water, while the results for lithium bromide aqueous solution are not satisfactory.

  3. A numerical study of three-dimensional viscous interactions of vortices with a free surface

    NASA Astrophysics Data System (ADS)

    Dommermuth, D.; Yue, D.

    Semi-implicit and explicit numerical methods are developed for the direct simulation of the three-dimensional Navier-Stokes equations with a free surface. The efficiency of a novel multigrid flow solver permits the simulation of three-dimensional flows with free surfaces at low Reynolds and Froude numbers. The numerical schemes are used to study vortex rings and tubes interacting with walls and free surfaces. In the case of vortex rings interacting with a no-slip wall observations of the formation of secondary and tertiary vortex rings agree qualitatively with experimental measurements. When a free surface is present, the results are sensitive to the Froude number. For sufficiently low Froude numbers, the free surface behaves like a free-slip wall, which agrees qualitatively with experimental observations of vortex rings interacting with clean free surfaces. At intermediate Froude numbers, the normal incidence of a vortex ring with a clean free surface results in the formation of secondary vortex rings. Numerical studies of vortex tubes interacting with free surfaces show two possible mechanisms for the reconnection of vorticity with a free surface including primary and secondary vorticity reconnections. One type of primary vorticity reconnection should result in a cusp pattern on the free surface and secondary vorticity reconnections should manifest themselves as paired dimples on the free surface. The essential stages of the reconnection of secondary vorticity with the free surface are as follows: generation of helical vortex sheets by the primary vortex tube, stripping of the helical vortex sheets due to self-induced straining flows, attachment of the helical vortex sheets to the separated free-surface boundary layer, wrapping of U-shaped vortices around the primary vortex tube, feeding of boundary-layer vorticity into the U-vortices, and reconnection of U-vortices with the free surface. We provide evidence which suggests that the striations that may be observed

  4. Lithium

    MedlinePlus

    ... mania (frenzied, abnormally excited mood) in people with bipolar disorder (manic-depressive disorder; a disease that causes episodes of depression, episodes of mania, and other abnormal moods). Lithium is in a ... antimanic agents. It works by decreasing abnormal activity in the brain.

  5. Effect of free surface shape on combined thermocapillary and natural convection

    NASA Technical Reports Server (NTRS)

    Kamotani, Yasuhiro; Platt, Jonathan

    1992-01-01

    Combined thermocapillary and natural convection in an open square cavity with differentially-heated side walls is studied numerically as well as experimentally. The test fluid is silicone oil with Prandtl number of 105. The shape of fluid-free surface is made either flat or curved to study its effect on the flow. A finite difference scheme to deal with a curved free surface is developed. The experimental results shown agree with the numerical results. With the curved-free surface, the flow and local heat transfer rate are reduced in the corner regions, and a sharp peak in heat transfer rate at the top edge of the cold wall disappears.

  6. Can a dike "feel" a free surface?

    NASA Astrophysics Data System (ADS)

    Pansino, S.; Taisne, B.

    2015-12-01

    This study uses analogue experiments to examine the various factors that could influence the dynamic or arrest of a dike prior to an eruption. Dike propagation has been well-studied from the perspective of analogue experiments and it has been shown how various competing forces interact (buoyancy, viscosity, elastic properties, fracture toughness,…). It has been observed that dikes experience acceleration as they approach a free surface, which theoretically is due to increasing stress intensity as distance to the free surface decreases. Other unrelated studies analysed the constant-volume propagation of low-surface-energy liquids (e.g. hydrophilic liquids) in a semi-infinite medium and found the propagation rate to decelerate, as liquid gradually transferred from the head region to the tail and buoyancy abated. In contrast, high-surface-energy fluids transfer negligible quantities of their volume into the tail region, essentially maintain their volume, and experience no such deceleration. This study focuses on the aforementioned factors influencing dike propagation, acceleration due to a free surface and deceleration due to head volume loss, to determine what their combined effect is on magma eruptability. As previous studies used hydrophobic liquids to investigate free-surface effects, and as magma is expected to have a low surface energy with the crust (they are both silicate), hydrophilic liquids (e.g. glucose syrup) are used in this study. Each experiment is arranged to have a free surface condition occupying half of the apparatus, and a no-slip condition occupying the other half, which allows for side-by-side comparison. The results are analysed to determine the minimum volume needed for a dike to erupt; failure to erupt implies that the dike would instead come to arrest in the crust.

  7. A liquid metal flume for free surface magnetohydrodynamic experiments

    NASA Astrophysics Data System (ADS)

    Nornberg, M. D.; Ji, H.; Peterson, J. L.; Rhoads, J. R.

    2008-09-01

    We present an experiment designed to study magnetohydrodynamic effects in free surface channel flow. The wide aspect ratio channel (the width to height ratio is about 15) is completely enclosed in an inert atmosphere to prevent oxidization of the liquid metal. A custom-designed pump reduces entrainment of oxygen, which was found to be a problem with standard centrifugal and gear pumps. Laser Doppler velocimetry experiments characterize velocity profiles of the flow. Various flow constraints mitigate secondary circulation and end effects on the flow. Measurements of the wave propagation characteristics in the liquid metal demonstrate the surfactant effect of surface oxides and the damping of fluctuations by a cross-channel magnetic field.

  8. A Liquid Metal Flume for Free Surface Magnetohydrodynamic Experiments

    SciTech Connect

    Nornberg, M.D.; Ji, H.; Peterson, J.L.; Rhoads, J.R.

    2008-08-27

    We present an experiment designed to study magnetohydrodynamic effects in free-surface channel flow. The wide aspect ratio channel (the width to height ratio is about 15) is completely enclosed in an inert atmosphere to prevent oxidization of the liquid metal. A custom-designed pump reduces entrainment of oxygen, which was found to be a problem with standard centrifugal and gear pumps. Laser Doppler Velocimetry experiments characterize velocity profiles of the flow. Various flow constraints mitigate secondary circulation and end effects on the flow. Measurements of the wave propagation characteristics in the liquid metal demonstrate the surfactant effect of surface oxides and the damping of fluctuations by a cross-channel magnetic field.

  9. Experiments on turbulence beneath a free surface in a stationary field generated by a Crump weir: turbulence structure and correlation with the free surface

    NASA Astrophysics Data System (ADS)

    Longo, Sandro

    2011-01-01

    This paper is a companion paper to a study devoted to the analysis of experimental instantaneous fluid levels and three-component fluid velocity measurements in a stationary flow field generated by a Crump weir in a laboratory flume, using an ultrasonic distance sensor and a three-probe arrangement of an ultrasonic Doppler velocity profiler (UVP) (Longo in Exp Fluids, doi: 10.1007/s00348-010-0881-5, 2010). Whereas Longo (Exp Fluids, doi: 10.1007/s00348-010-0881-5, 2010) deals with a general overview of the problem, the description of the experiments and the analysis of the free surface statistics and relevant scales, the present manuscript is devoted to a detailed analysis of the turbulence and the correlation with the free surface. The data are elaborated by obtaining the macroturbulence Reynolds tensor, using conditional averages based on free surface-fluctuation statistics. We also compute the two-point correlations of fluid velocity, the micro-scale and the integral scale, the correlation between free surface and the turbulence beneath. A free surface-boundary layer was detected having a thickness proportional to the root mean square of the free surface-height series and with a velocity scale that correlates well with the free surface-elevation time gradient. Most of the relevant state variables, such as the mean velocity and Reynolds stress components, collapse to a single curve if scaled appropriately. There are many indicators that a specific regime occurs that has an optimal tuning between the free surface and turbulence. In this regime, the length scales are considered as an indicator.

  10. A flowing liquid lithium limiter for the Experimental Advanced Superconducting Tokamak.

    PubMed

    Ren, J; Zuo, G Z; Hu, J S; Sun, Z; Yang, Q X; Li, J G; Zakharov, L E; Xie, H; Chen, Z X

    2015-02-01

    A program involving the extensive and systematic use of lithium (Li) as a "first," or plasma-facing, surface in Tokamak fusion research devices located at Institute of Plasma Physics, Chinese Academy of Sciences, was started in 2009. Many remarkable results have been obtained by the application of Li coatings in Experimental Advanced Superconducting Tokamak (EAST) and liquid Li limiters in the HT-7 Tokamak-both located at the institute. In furtherance of the lithium program, a flowing liquid lithium (FLiLi) limiter system has been designed and manufactured for EAST. The design of the FLiLi limiter is based on the concept of a thin flowing film which was previously tested in HT-7. Exploiting the capabilities of the existing material and plasma evaluation system on EAST, the limiter will be pre-wetted with Li and mechanically translated to the edge of EAST during plasma discharges. The limiter will employ a novel electro-magnetic pump which is designed to drive liquid Li flow from a collector at the bottom of limiter into a distributor at its top, and thus supply a continuously flowing liquid Li film to the wetted plasma-facing surface. This paper focuses on the major design elements of the FLiLi limiter. In addition, a simulation of incoming heat flux has shown that the distribution of heat flux on the limiter surface is acceptable for a future test of power extraction on EAST. PMID:25725839

  11. A flowing liquid lithium limiter for the Experimental Advanced Superconducting Tokamak

    SciTech Connect

    Ren, J.; Zuo, G. Z.; Hu, J. S.; Sun, Z.; Yang, Q. X.; Li, J. G.; Xie, H.; Chen, Z. X.; Zakharov, L. E.

    2015-02-15

    A program involving the extensive and systematic use of lithium (Li) as a “first,” or plasma-facing, surface in Tokamak fusion research devices located at Institute of Plasma Physics, Chinese Academy of Sciences, was started in 2009. Many remarkable results have been obtained by the application of Li coatings in Experimental Advanced Superconducting Tokamak (EAST) and liquid Li limiters in the HT-7 Tokamak—both located at the institute. In furtherance of the lithium program, a flowing liquid lithium (FLiLi) limiter system has been designed and manufactured for EAST. The design of the FLiLi limiter is based on the concept of a thin flowing film which was previously tested in HT-7. Exploiting the capabilities of the existing material and plasma evaluation system on EAST, the limiter will be pre-wetted with Li and mechanically translated to the edge of EAST during plasma discharges. The limiter will employ a novel electro-magnetic pump which is designed to drive liquid Li flow from a collector at the bottom of limiter into a distributor at its top, and thus supply a continuously flowing liquid Li film to the wetted plasma-facing surface. This paper focuses on the major design elements of the FLiLi limiter. In addition, a simulation of incoming heat flux has shown that the distribution of heat flux on the limiter surface is acceptable for a future test of power extraction on EAST.

  12. A flowing liquid lithium limiter for the Experimental Advanced Superconducting Tokamak

    NASA Astrophysics Data System (ADS)

    Ren, J.; Zuo, G. Z.; Hu, J. S.; Sun, Z.; Yang, Q. X.; Li, J. G.; Zakharov, L. E.; Xie, H.; Chen, Z. X.

    2015-02-01

    A program involving the extensive and systematic use of lithium (Li) as a "first," or plasma-facing, surface in Tokamak fusion research devices located at Institute of Plasma Physics, Chinese Academy of Sciences, was started in 2009. Many remarkable results have been obtained by the application of Li coatings in Experimental Advanced Superconducting Tokamak (EAST) and liquid Li limiters in the HT-7 Tokamak—both located at the institute. In furtherance of the lithium program, a flowing liquid lithium (FLiLi) limiter system has been designed and manufactured for EAST. The design of the FLiLi limiter is based on the concept of a thin flowing film which was previously tested in HT-7. Exploiting the capabilities of the existing material and plasma evaluation system on EAST, the limiter will be pre-wetted with Li and mechanically translated to the edge of EAST during plasma discharges. The limiter will employ a novel electro-magnetic pump which is designed to drive liquid Li flow from a collector at the bottom of limiter into a distributor at its top, and thus supply a continuously flowing liquid Li film to the wetted plasma-facing surface. This paper focuses on the major design elements of the FLiLi limiter. In addition, a simulation of incoming heat flux has shown that the distribution of heat flux on the limiter surface is acceptable for a future test of power extraction on EAST.

  13. Free surface deformation and heat transfer by thermocapillary convection

    NASA Astrophysics Data System (ADS)

    Fuhrmann, Eckart; Dreyer, Michael; Basting, Steffen; Bänsch, Eberhard

    2016-04-01

    Knowing the location of the free liquid/gas surface and the heat transfer from the wall towards the fluid is of paramount importance in the design and the optimization of cryogenic upper stage tanks for launchers with ballistic phases, where residual accelerations are smaller by up to four orders of magnitude compared to the gravity acceleration on earth. This changes the driving forces drastically: free surfaces become capillary dominated and natural or free convection is replaced by thermocapillary convection if a non-condensable gas is present. In this paper we report on a sounding rocket experiment that provided data of a liquid free surface with a nonisothermal boundary condition, i.e. a preheated test cell was filled with a cold but storable liquid in low gravity. The corresponding thermocapillary convection (driven by the temperature dependence of the surface tension) created a velocity field directed away from the hot wall towards the colder liquid and then in turn back at the bottom towards the wall. A deformation of the free surface resulting in an apparent contact angle rather different from the microscopic one could be observed. The thermocapillary flow convected the heat from the wall to the liquid and increased the heat transfer compared to pure conduction significantly. The paper presents results of the apparent contact angle as a function of the dimensionless numbers (Weber-Marangoni and Reynolds-Marangoni number) as well as heat transfer data in the form of a Nusselt number. Experimental results are complemented by corresponding numerical simulations with the commercial software Flow3D and the inhouse code Navier.

  14. Thermocapillary convection in two immiscible liquid layers with free surface

    NASA Technical Reports Server (NTRS)

    Doi, Takao; Koster, Jean N.

    1993-01-01

    Thermocapillary convection is studied in two immiscible liquid layers with one free surface, one liquid/liquid interface, and differential heating applied parallel to the interfaces. An analytical solution is introduced for infinite horizontal layers. The defining parameter for the flow pattern is lambda, the ratio of the temperature coefficient of the interfacial tension to that of the surface tension. Four different flow patterns exist under zero gravity conditions. 'Halt' conditions which halt the fluid motion in the lower encapsulated liquid layer have been found. A numerical experiment is carried out to study effects of vertical end walls on the double layer convection in a 2D cavity. The halt condition obtained from the analytical study is found to be valid in the limit of small Reynolds numbers. The flow in the encapsulated liquid layer can be suppressed substantially.

  15. Flow Boiling Heat Transfer to Lithium Bromide Aqueous Solution in Subcooled Region

    NASA Astrophysics Data System (ADS)

    Kaji, Masao; Furukawa, Masahiro; Nishizumi, Takeharu; Ozaki, Shinji; Sekoguchi, Kotohiko

    A theoretical prediction model of the boiling heat transfer coefficient in the subcooled region for water and lithium bromide aqueous solution flowing in a rectangular channel is proposed. In the present heat transfer model, a heat flux is assumed to consist of both the forced convective and the boiling effect components. The forced convective component is evaluated from the empirical correlation of convective heat transfer coefficient for single-phase flow considering the effect of increase of liquid velocity due to net vapor generation. Empirical correlations for determining the heat flux due to the boiling effect and the quality at the onset point of net vapor generation are obtained from the data presented in the first report1). Agreement between the present theoretical prediction and the experimental data is satisfactorily good both for water and lithium bromide aqueous solution.

  16. First results of the use of a continuously flowing lithium limiter in high performance discharges in the EAST device

    NASA Astrophysics Data System (ADS)

    Hu, J. S.; Zuo, G. Z.; Ren, J.; Yang, Q. X.; Chen, Z. X.; Xu, H.; Zakharov, L. E.; Maingi, R.; Gentile, C.; Meng, X. C.; Sun, Z.; Xu, W.; Chen, Y.; Fan, D.; Yan, N.; Duan, Y. M.; Yang, Z. D.; Zhao, H. L.; Song, Y. T.; Zhang, X. D.; Wan, B. N.; Li, J. G.; EAST Team

    2016-04-01

    As an alternative choice of solid plasma facing components (PFCs), flowing liquid lithium can serve as a limiter or divertor PFC and offers a self-healing surface with acceptable heat removal and good impurity control. Such a system could improve plasma performance, and therefore be attractive for future fusion devices. Recently, a continuously flowing liquid lithium (FLiLi) limiter has been successfully designed and tested in the EAST superconducting tokamak. A circulating lithium layer with a thickness of  <0.1 mm and a flow rate ~2 cm3 s-1 was achieved. A novel in-vessel electro-magnetic pump, working with the toroidal magnetic field of the EAST device, was reliable to control the lithium flow speed. The flowing liquid limiter was found to be fully compatible with various plasma scenarios, including high confinement mode plasmas heated by lower hybrid waves or by neutral beam injection. It was also found that the controllable lithium emission from the limiter was beneficial for the reduction of recycling and impurities, for the reduction of divertor heat flux, and in certain cases, for the improvement of plasma stored energy, which bodes well application for the use of flowing liquid lithium PFCs in future fusion devices.

  17. Thermal analysis and two-directional air flow thermal management for lithium-ion battery pack

    NASA Astrophysics Data System (ADS)

    Yu, Kuahai; Yang, Xi; Cheng, Yongzhou; Li, Changhao

    2014-12-01

    Thermal management is a routine but crucial strategy to ensure thermal stability and long-term durability of the lithium-ion batteries. An air-flow-integrated thermal management system is designed in the present study to dissipate heat generation and uniformize the distribution of temperature in the lithium-ion batteries. The system contains of two types of air ducts with independent intake channels and fans. One is to cool the batteries through the regular channel, and the other minimizes the heat accumulations in the middle pack of batteries through jet cooling. A three-dimensional anisotropic heat transfer model is developed to describe the thermal behavior of the lithium-ion batteries with the integration of heat generation theory, and validated through both simulations and experiments. Moreover, the simulations and experiments show that the maximum temperature can be decreased to 33.1 °C through the new thermal management system in comparison with 42.3 °C through the traditional ones, and temperature uniformity of the lithium-ion battery packs is enhanced, significantly.

  18. A carbon-free lithium-ion solid dispersion redox couple with low viscosity for redox flow batteries

    NASA Astrophysics Data System (ADS)

    Qi, Zhaoxiang; Koenig, Gary M.

    2016-08-01

    A new type of non-aqueous redox couple without carbon additives for flow batteries is proposed and the target anolyte chemistry is demonstrated. The so-called "Solid Dispersion Redox Couple" incorporates solid electroactive materials dispersed in organic lithium-ion battery electrolyte as its flowing suspension. In this work, a unique and systematic characterization approach has been used to study the flow battery redox couple in half cell demonstrations relative to a lithium electrode. An electrolyte laden with Li4Ti5O12 (LTO) has been characterized in multiple specially designed lithium half cell configurations. The flow battery redox couple described in this report has relatively low viscosity, especially in comparison to other flow batteries with solid active materials. The lack of carbon additive allows characterization of the electrochemical properties of the electroactive material in flow without the complication of conductive additives and unambiguous observation of the electrorheological coupling in these dispersed particle systems.

  19. High-energy density nonaqueous all redox flow lithium battery enabled with a polymeric membrane.

    PubMed

    Jia, Chuankun; Pan, Feng; Zhu, Yun Guang; Huang, Qizhao; Lu, Li; Wang, Qing

    2015-11-01

    Redox flow batteries (RFBs) are considered one of the most promising large-scale energy storage technologies. However, conventional RFBs suffer from low energy density due to the low solubility of the active materials in electrolyte. On the basis of the redox targeting reactions of battery materials, the redox flow lithium battery (RFLB) demonstrated in this report presents a disruptive approach to drastically enhancing the energy density of flow batteries. With LiFePO4 and TiO2 as the cathodic and anodic Li storage materials, respectively, the tank energy density of RFLB could reach ~500 watt-hours per liter (50% porosity), which is 10 times higher than that of a vanadium redox flow battery. The cell exhibits good electrochemical performance under a prolonged cycling test. Our prototype RFLB full cell paves the way toward the development of a new generation of flow batteries for large-scale energy storage. PMID:26702440

  20. High–energy density nonaqueous all redox flow lithium battery enabled with a polymeric membrane

    PubMed Central

    Jia, Chuankun; Pan, Feng; Zhu, Yun Guang; Huang, Qizhao; Lu, Li; Wang, Qing

    2015-01-01

    Redox flow batteries (RFBs) are considered one of the most promising large-scale energy storage technologies. However, conventional RFBs suffer from low energy density due to the low solubility of the active materials in electrolyte. On the basis of the redox targeting reactions of battery materials, the redox flow lithium battery (RFLB) demonstrated in this report presents a disruptive approach to drastically enhancing the energy density of flow batteries. With LiFePO4 and TiO2 as the cathodic and anodic Li storage materials, respectively, the tank energy density of RFLB could reach ~500 watt-hours per liter (50% porosity), which is 10 times higher than that of a vanadium redox flow battery. The cell exhibits good electrochemical performance under a prolonged cycling test. Our prototype RFLB full cell paves the way toward the development of a new generation of flow batteries for large-scale energy storage. PMID:26702440

  1. Material and Energy Flows in the Production of Cathode and Anode Materials for Lithium Ion Batteries

    SciTech Connect

    Dunn, Jennifer B.; James, Christine; Gaines, Linda; Gallagher, Kevin; Dai, Qiang; Kelly, Jarod C.

    2015-09-01

    The Greenhouse gases, Regulated Emissions and Energy use in Transportation (GREET) model has been expanded to include four new cathode materials that can be used in the analysis of battery-powered vehicles: lithium nickel cobalt manganese oxide (LiNi0.4Co0.2Mn0.4O2 [NMC]), lithium iron phosphate (LiFePO4 [LFP]), lithium cobalt oxide (LiCoO2 [LCO]), and an advanced lithium cathode (0.5Li2MnO3∙0.5LiNi0.44Co0.25Mn0.31O2 [LMR-NMC]). In GREET, these cathode materials are incorporated into batteries with graphite anodes. In the case of the LMR-NMC cathode, the anode is either graphite or a graphite-silicon blend. Lithium metal is also an emerging anode material. This report documents the material and energy flows of producing each of these cathode and anode materials from raw material extraction through the preparation stage. For some cathode materials, we considered solid state and hydrothermal preparation methods. Further, we used Argonne National Laboratory’s Battery Performance and Cost (BatPaC) model to determine battery composition (e.g., masses of cathode, anode, electrolyte, housing materials) when different cathode materials were used in the battery. Our analysis concluded that cobalt- and nickel-containing compounds are the most energy intensive to produce.

  2. Free-surface interactions in the wake of an inverted cylindrical pendulum

    NASA Astrophysics Data System (ADS)

    Voorhees, A. V.; Wei, T.

    2001-11-01

    Vortex-induced vibration experiments of a low-mass circular cylinder were conducted in the Rutgers Free-Surface Water Tunnel. The focus of this study was to ascertain the extent of free-surface effects on the cylinder motion. A 2.54-cm diameter, 160 cm long circular cylinder was mounted vertically in the test section as an inverted pendulum. The bottom was attached to the tunnel floor by a leaf spring and the upper end protruded through the free surface. Strong vertical flows, associated with the Kármán vortex street, have been observed in the wake; such flows have not been found in transverse oscillator wakes that exhibit similar response data. In addition, these vertical flows are markedly altered near the free surface. The 3-D wake and free-surface interactions were examined in the synchronization regime at Re = 3800. In this regime, the amplitude response exhibits highly modulated, quasi-periodic beating. Temporally and spatially-resolved, phase-averaged DPIV measurements were made in horizontal and cross-stream planes. The oblique nature, vertical and streamwise, of the vortex shedding will be shown using composite time plots from both measurement planes. Changes in vortex shedding phase and formation length will be related to response amplitude modulations.

  3. Free Surface and Flapping Foil Interactions

    NASA Astrophysics Data System (ADS)

    Ananthakrishnan, Palaniswamy

    2014-11-01

    Flapping foils for station-keeping of a near-surface body in a current is analyzed using a finite-difference method based on boundary-fitted coordinates. The foils are hinge-connected to the aft of the body and subject to pitch oscillation. Results are obtained for a range of Strouhal number, Froude number, unsteady frequency parameter τ, Reynolds number and the depth of foil submergence. Results show that at low Strouhal number (St < 0 . 1) and sub-critical unsteady parameter τ < 0 . 25 , the flapping generates drag instead of thrust. At high Strouhal number and super-critical value of the unsteady parameter (τ > 0 . 25) flapping generates high thrust with low efficiency. Thrust and efficiency are found to decrease with decreasing submergence depth of the foil. At the critical τ = 0 . 25 and shallow submergence of the foil, the standing wave generated above the foil continues to grow until breaking; both the thrust and efficiency of the foil are reduced at the critical τ. The necessary conditions for optimal thrust generation by a flapping foil underneath the free surface are found to be (i) Strouhal number in the range from 0.25 to 0.35, (ii) unsteady parameter τ > 0 . 25 and (iii) the maximum angle of attack less than 15° for the flat-plate foil. Supported by the US Office of Naval Research through the Naval Engineering Education Center (NEEC) Consortium of the University of Michigan, Ann Arbor.

  4. 46 CFR 42.20-10 - Free surface.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 2 2014-10-01 2014-10-01 false Free surface. 42.20-10 Section 42.20-10 Shipping COAST... Freeboards § 42.20-10 Free surface. When doing the calculations required in §§ 42.20-6(a), 42.20-7(a) and 42.20-8(a), the effect of free surface of the following liquids must be included: (a) For each type...

  5. 46 CFR 42.20-10 - Free surface.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Free surface. 42.20-10 Section 42.20-10 Shipping COAST... Freeboards § 42.20-10 Free surface. When doing the calculations required in §§ 42.20-6(a), 42.20-7(a) and 42.20-8(a), the effect of free surface of the following liquids must be included: (a) For each type...

  6. 46 CFR 42.20-10 - Free surface.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Free surface. 42.20-10 Section 42.20-10 Shipping COAST... Freeboards § 42.20-10 Free surface. When doing the calculations required in §§ 42.20-6(a), 42.20-7(a) and 42.20-8(a), the effect of free surface of the following liquids must be included: (a) For each type...

  7. 46 CFR 42.20-10 - Free surface.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 2 2013-10-01 2013-10-01 false Free surface. 42.20-10 Section 42.20-10 Shipping COAST... Freeboards § 42.20-10 Free surface. When doing the calculations required in §§ 42.20-6(a), 42.20-7(a) and 42.20-8(a), the effect of free surface of the following liquids must be included: (a) For each type...

  8. 46 CFR 42.20-10 - Free surface.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 2 2012-10-01 2012-10-01 false Free surface. 42.20-10 Section 42.20-10 Shipping COAST... Freeboards § 42.20-10 Free surface. When doing the calculations required in §§ 42.20-6(a), 42.20-7(a) and 42.20-8(a), the effect of free surface of the following liquids must be included: (a) For each type...

  9. Development of liquid-lithium film jet-flow for the target of (7)Li(p,n)(7)Be reactions for BNCT.

    PubMed

    Kobayashi, Tooru; Miura, Kuniaki; Hayashizaki, Noriyosu; Aritomi, Masanori

    2014-06-01

    A feasibility study on liquid lithium target in the form of a flowing film was performed to evaluate its potential use as a neutron generation target of (7)Li(p,n)(7)Be reaction in BNCT. The target is a windowless-type flowing film on a concave wall. Its configuration was adapted for a proton beam which is 30mm in diameter and with energy and current of up to 3MeV and 20mA, respectively. The flowing film of liquid lithium was 0.6mm in thickness, 50mm in width and 50mm in length. The shapes of the nozzle and concave back wall, which create a stable flowing film jet, were decided based on water experiments. A lithium hydrodynamic experiment was performed to observe the stability of liquid lithium flow behavior. The flowing film of liquid lithium was found to be feasible at temperatures below the liquid lithium boiling saturation of 342°C at the surface pressure of 1×10(-3)Pa. Using a proto-type liquid lithium-circulating loop for BNCT, the stability of the film flow was confirmed for velocities up to 30m/s at 220°C and 250°C in vacuum at a pressure lower than 10(-3) Pa. It is expected that for practical use, a flowing liquid lithium target of a windowless type can solve the problem of radiation damage and target cooling. PMID:24412425

  10. On the Way Toward Understanding Solution Chemistry of Lithium Polysulfides for High Energy Li-S Redox Flow Batteries

    SciTech Connect

    Pan, Huilin; Wei, Xiaoliang; Henderson, Wesley A.; Shao, Yuyan; Chen, Junzheng; Bhattacharya, Priyanka; Xiao, Jie; Liu, Jun

    2015-04-27

    Lithium sulfur (Li-S) redox flow battery (RFB) is a promising candidate for high energy large-scale energy storage application due to good solubility of long-chain polysulfide species and low cost of sulfur. In this report, recent progress and new concepts for Li-S redox flow batteries are discussed with an emphasis on the fundamental understanding and control of lithium polysulfide chemistry to enable the development of liquid phase Li-S redox flow prototype cells. These differ significantly from conventional static Li-S batteries targeting for vehicle electrification. A high solubility of the different lithium polysulfides generated at different depths of discharge and states of charge is required for a flow battery in order to take full advantage of the multiple electron transitions between elemental sulfur and Li2S. A new DMSO-based electrolyte is proposed for Li-S redox flow batteries, which not only enables the high solubility of lithium polysulfide species, especially for the short-chain species, but also results in excellent cycling with a high Coulombic efficiency. The challenges and opportunities for the Li-S redox flow concept have also been discussed in depth.

  11. On the interaction of a vertical shear layer with a free surface

    NASA Astrophysics Data System (ADS)

    Dabiri, Dana

    2003-04-01

    New experiments have been conducted using a combined free-surface gradient detector (FSGD) and digital particle image velocimetry (DPIV) technique to study the interaction between a vertical shear layer, created by a surface-piercing splitter plate, and a free surface. The emphasis of this study is on understanding aspects of the interaction between the free-surface deformation (FSD) and the near-surface turbulence through the correlations between the elevation and the vorticity fields, and the spectral behaviour of the near-surface pressure. The Reynolds number of the present study, based on visual thickness and the velocity average of the two streams, is 12 100. Mean results for the velocity and vorticity fields show that self-similarity is achieved. Instantaneous data sets show that at the free surface, vortex tubes within the main rollers connect normally with the free surface as is evidenced by strong vorticity as well as the strong deformations at the free surface. The instantaneous data sets also show that the streamwise vortices near the braid regions, while weaker than those seen in the main rollers, also reconnect with the free surface. Statistical analyses show that the FSD is strongly correlated with the near-surface vorticity field, as the correlation coefficients are quite high (˜ 0.7-0.8). The pressure spectrum slope within the shear layer near the surface is found to be -10/3, compared with the analytically derived value of -11/3 (George et al. 1984) found for a shear layer in unbounded flow.

  12. Self-induced oscillation of free surface coupled with the axisymmetric jet and structure

    SciTech Connect

    Someya, Satoshi; Okamoto, Koji; Madarame, Haruki

    1996-08-01

    New self-induced free-surface oscillations were discovered, which were caused by the interaction between a jet, a free surface and a structure. A submerged upward round jet was injected into a cylindrical tank from an inlet nozzle at the bottom center. The jet impinged on a cylindrical rod (UIS) which was set just beneath the free surface of the tank. Then, the jet turned its direction along UIS and reached the free surface making a swell around UIS. Under a certain condition of jet velocity and UIS depth, several kinds of self-induced free surface oscillation were observed, which were roughly classified into two modes with their surface shapes. One had no diametric node and two nodal circles, (0,2), and the other had one node in each direction, (1,1). The (0,2) mode oscillation was divided into two types with their flow pattern. In the (0,2) mode with outward surface velocity, (0,2){sub OUT}, its oscillating frequency decreased with increasing jet velocity. The swell of the free surface characterized (0,2){sub OUT} mode oscillation which was different from the theoretical (0,2) mode sloshing. In the (0,2) mode with inward surface velocity, (0,2){sub IN}, its frequency was independent of jet velocity. Its growth mechanism was thought to be similar to that of self-induced sloshing in the previous study. The (1,1) mode oscillation was also divided into two types with the appearance of the swell around UIS. The (1,1) mode with swelling of the free surface, (1,1){sub {alpha}}, was found to be the same as Jet-Flutter in a cylindrical tank without UIS. This is important to evaluate performance of LMFBR.

  13. Hydrodynamic coefficients of an oscillating ellipsoid moving in the free surface

    NASA Astrophysics Data System (ADS)

    Inglis, R. B.; Price, W. G.

    1980-10-01

    The frequency dependent heave, pitch, sway, and yaw hydrodynamic coefficients associated with an oscillating ellipsoid traveling with forward speed in the free surface are evaluated from a three-dimensional potential flow analysis. The free-surface boundary condition in the mathematical model either includes the influence of forward speed or is simplified to the equivalent zero speed case. This variation produces a velocity potential which is either frequency and speed dependent or just frequency dependent. The influence of forward speed on all the hydrodynamic coefficients is discussed.

  14. Computational Fluid Dynamics Modeling of a Lithium/Thionyl Chloride Battery with Electrolyte Flow

    SciTech Connect

    Gu, W.B.; Jungst, Rudolph G.; Nagasubramanian, Ganesan; Wang, C.Y.; Weidner, John.

    1999-06-11

    A two-dimensional model is developed to simulate discharge of a lithium/thionyl chloride primary battery. The model accounts for not only transport of species and charge, but also the electrode porosity variations and the electrolyte flow induced by the volume reduction caused by electrochemical reactions. Numerical simulations are performed using a finite volume method of computational fluid dynamics. The predicted discharge curves for various temperatures are compared to the experimental data with excellent agreement. Moreover, the simulation results. in conjunction with computer visualization and animation techniques, confirm that cell utilization in the temperature and current range of interest is limited by pore plugging or clogging of the front side of the cathode as a result of LiCl precipitation. The detailed two-dimensional flow simulation also shows that the electrolyte is replenished from the cell header predominantly through the separator into the front of the cathode during most parts of the discharge, especially for higher cell temperatures.

  15. A numerical procedure for transient free surface seepage through fracture networks

    NASA Astrophysics Data System (ADS)

    Jiang, Qinghui; Ye, Zuyang; Zhou, Chuangbing

    2014-11-01

    A parabolic variational inequality (PVI) formulation is presented for the transient free surface seepage problem defined for a whole fracture network. Because the seepage faces are specified as Signorini-type conditions, the PVI formulation can effectively eliminate the singularity of spillpoints that evolve with time. By introducing a continuous penalty function to replace the original Heaviside function, a finite element procedure based on the PVI formulation is developed to predict the transient free surface response in the fracture network. The effects of the penalty parameter on the solution precision are analyzed. A relative error formula for evaluating the flow losses at steady state caused by the penalty parameter is obtained. To validate the proposed method, three typical examples are solved. The solutions for the first example are compared with the experimental results. The results from the last two examples further demonstrate that the orientation, extent and density of fractures significantly affect the free surface seepage behavior in the fracture network.

  16. Apple Snail: a Bio Cleaner of the Water Free Surface.

    NASA Astrophysics Data System (ADS)

    Bassiri, Golnaz

    2005-11-01

    Oil spills from tankers represent a threat for shorelines and marine life. Despite continuing research, there has been little change in the fundamental technology for dealing with oil spills. An experimental investigation of the feeding strategy of Apple snails from the water free surface, called surface film feeding, is being studied motivated by the need to develop new techniques to recover oil spills. To feed on floating food (usually a thin layer of microorganisms), the apple snail forms a funnel with its foot and pulls the free surface toward the funnel. High speed imaging and particle image velocimetry were used in the present investigation to measure the free surface motion and to investigate the mechanism used by the apple snails to pull the free surface. The results suggest that the snail pulls the free surface via the wavy motion of the muscles in its funnel.

  17. Numerical Simulation of Floating Bodies in Extreme Free Surface Waves

    NASA Astrophysics Data System (ADS)

    Hu, Zheng Zheng; Causon, Derek; Mingham, Clive; Qiang, Ling

    2010-05-01

    and efficient. Firstly, extreme design wave conditions are generated in an empty NWT and compared with physical experiments as a precursor to calculations to investigate the survivability of the Bobber device operating in a challenging wave climate. Secondly, we consider a bench-mark test case involving in a first order regular wave maker acting on a fixed cylinder and Pelamis. Finally, a floating Bobber has been simulated under extreme wave conditions. These results will be reported at the meeting. Causon D.M., Ingram D.M., Mingham C.G., Yang G. Pearson R.V. (2000). Calculation of shallow water flows using a Cartesian cut cell approach. Advances in Water resources, 23: 545-562. Causon D.M., Ingram D.M., Mingham C.G. (2000). A Cartesian cut cell method for shallow water flows with moving boundaries. Advances in Water resources, 24: 899-911. Dalzell J.F. 1999 A note on finite depth second-order wave-wave interactions. Appl. Ocean Res. 21, 105-111. Ning D.Z., Zang J., Liu S.X. Eatock Taylor R. Teng B. & Taylor P.H. 2009 Free surface and wave kinematics for nonlinear focused wave groups. J. Ocean Engineering. Accepted. Hu Z.Z., Causon D.M., Mingham C.M. and Qian L.(2009). Numerical wave tank study of a wave energy converter in heave. Proceedlings 19th ISOPE conference, Osaka, Japan Qian L., Causon D.M. & Mingham C.G., Ingram D.M. 2006 A free-surface capturing method for two fluid flows with moving bodies. Proc. Roy. Soc. London, Vol. A 462 21-42.

  18. Low-Reynolds-number rising of a bubble near a free surface at vanishing Bond number

    NASA Astrophysics Data System (ADS)

    Guémas, Marine; Sellier, Antoine; Pigeonneau, Franck

    2016-06-01

    This work considers a nearly spherical bubble and a nearly flat free surface interacting under buoyancy at vanishing Bond number Bo. For each perturbed surface, the deviation from the unperturbed shape is asymptotically obtained at leading order on Bo. The task appeals to the normal traction exerted on the unperturbed surface by the Stokes flow due to a spherical bubble translating toward a flat free surface. The free surface problem is then found to be well-posed and to admit a solution in closed form when gravity is still present in the linear differential equation governing the perturbed profile through a term proportional to Bo. In contrast, the bubble problem amazingly turns out to be over-determined. It however becomes well-posed if the requirement of horizontal tangent planes at the perturbed bubble north and south poles is discarded or if the term proportional to Bo is omitted. Both previous approaches turn out to predict for a small Bond number, quite close solutions except in the very vicinity of the bubble poles. The numerical solution of the proposed asymptotic analysis shows in the overlapping range Bo = O ( 0.1 ) and for both the bubble and the free surface perturbed shapes, a good agreement with a quite different boundary element approach developed in Pigeonneau and Sellier ["Low-Reynolds-number gravity-driven migration and deformation of bubbles near a free surface," Phys. Fluids 23, 092102 (2011)]. It also provides approximated bubble and free surface shapes whose sensitivity to the bubble location is examined.

  19. Dynamics of free surface perturbations along an annular viscous film

    NASA Astrophysics Data System (ADS)

    Smolka, Linda B.; North, Justin; Guerra, Bree K.

    2008-03-01

    It is known that the free surface of an axisymmetric viscous film flowing down the outside of a thin vertical fiber under the influence of gravity becomes unstable to interfacial perturbations. We present an experimental study using fluids with different densities, surface tensions, and viscosities to investigate the growth and dynamics of these interfacial perturbations and to test the assumptions made by previous authors. We find that the initial perturbation growth is exponential, followed by a slower phase as the amplitude and wavelength saturate in size. Measurements of the perturbation growth for experiments conducted at low and moderate Reynolds numbers are compared to theoretical predictions developed from linear stability theory. Excellent agreement is found between predictions from a long-wave Stokes flow model [Craster and Matar, J. Fluid Mech. 553, 85 (2006)] and data, while fair to excellent agreement (depending on fiber size) is found between predictions from a moderate-Reynolds-number model [Sisoev , Chem. Eng. Sci. 61, 7279 (2006)] and data. Furthermore, we find that a known transition in the longer-time perturbation dynamics from unsteady to steady behavior at a critical flow rate Qc is correlated with a transition in the rate at which perturbations naturally form along the fiber. For QQc (unsteady case), the rate of perturbation formation is modulated. As a result, the position along the fiber where perturbations form oscillates irregularly, and the initial speed and spacing between perturbations varies, resulting in the coalescence of neighboring perturbations further down the fiber.

  20. Influence of thermal stratification on the surfacing and clustering of floaters in free surface turbulence

    NASA Astrophysics Data System (ADS)

    Lovecchio, Salvatore; Zonta, Francesco; Soldati, Alfredo

    2014-10-01

    The dispersion of floaters, small organic particles lighter than water, on the free surface of an open turbulent channel flow subject to thermal stratification is studied by Direct Numerical Simulation (DNS) of turbulence and Lagrangian Particle Tracking (LPT). Constant heat flux is maintained at the free surface of the channel, the bottom wall is adiabatic and the turbulent flow is driven by a pressure gradient. This archetypal flow setup mimics an environmentally plausible situation which can be found in terrestrial water bodies. The free surface turbulence characteristic of such flows has a strong influence on the distribution of the floaters: the objective of this work is to study the effect of different regimes of stable stratification on the surface distribution of floaters. The distribution of the floaters can possibly influence the transfer of chemical species across the water/atmosphere interface. Our results show that the modification of turbulence due to the thermal stratification strongly influences the settling velocity of floaters in the bulk of the flow. At the surface, stratification effects are also observed on the clustering of the floaters: the filamentary patterns of floaters observed in unstratified turbulence are progressively lost as thermal stratification increases, and the distribution of the floaters remains roughly two-dimensional.

  1. Aqueous Lithium-Iodine Solar Flow Battery for the Simultaneous Conversion and Storage of Solar Energy.

    PubMed

    Yu, Mingzhe; McCulloch, William D; Beauchamp, Damian R; Huang, Zhongjie; Ren, Xiaodi; Wu, Yiying

    2015-07-01

    Integrating both photoelectric-conversion and energy-storage functions into one device allows for the more efficient solar energy usage. Here we demonstrate the concept of an aqueous lithium-iodine (Li-I) solar flow battery (SFB) by incorporation of a built-in dye-sensitized TiO2 photoelectrode in a Li-I redox flow battery via linkage of an I3(-)/I(-) based catholyte, for the simultaneous conversion and storage of solar energy. During the photoassisted charging process, I(-) ions are photoelectrochemically oxidized to I3(-), harvesting solar energy and storing it as chemical energy. The Li-I SFB can be charged at a voltage of 2.90 V under 1 sun AM 1.5 illumination, which is lower than its discharging voltage of 3.30 V. The charging voltage reduction translates to energy savings of close to 20% compared to conventional Li-I batteries. This concept also serves as a guiding design that can be extended to other metal-redox flow battery systems. PMID:26102317

  2. Free surface height deformation upstream of an array of model marine hydrokinetic devices

    NASA Astrophysics Data System (ADS)

    Riley, D. R.; Beninati, M. L.; Volpe, M. A.; Krane, M.

    2011-12-01

    The changes in flow velocity and free surface height upstream of an array of model marine hydrokinetic (MHK) devices are measured in small-scale flume. These models consist of a stationary perforated plate mounted to a cylinder. The perforated plates mimic the blockage ratio and head loss effects of rotating blades on the flow, and the cylinders represent typical support structures for MHK devices. Experimental results are used to for two purposes. First, they will be used validate numerical simulations being conducted in parallel. Second, they will be used to determine a spatial arrangement for a field testing array that optimizes energy extraction. The operating hypothesis is that the proper spatial arrangement of a MHK array can modify the incident flow so as to increase the fluid energy incident upon some of the MHK devices in the array, increasing the energy produced by the array. The testing is conducted in the hydraulic flume facility (32 ft long, 4 ft wide, and 1.25 ft deep) in the Environmental Fluid Mechanics and Hydraulics Laboratory (EFM&HL) at Bucknell University. Within the facility a small-scale testing platform which consists of a nozzle insert is used to accelerate the flow into a test section (2 ft wide, 2.5 ft long, and 0.75 ft deep), where the cylinder arrays are located. The model MHK devices sizes are scaled using the test section floor turbulent boundary layer thickness. Flow field measurements are performed using an Acoustic Doppler Velocimeter. Mapping of the free surface is accomplished with an ultrasonic liquid level finder. Both devices are positioned using a programmable gantry system that has access to the entire test section. For each array configuration tested, both the free surface height and flow field upstream of the model MHK array are accurately mapped. These measurements are combined with the free surface height measurements to estimate the total fluid energy upstream of the array.

  3. Undulatory swimming on a free surface

    NASA Astrophysics Data System (ADS)

    Godoy-Diana, Ramiro; Ramananarivo, Sophie; Gann, Olivia; Thiria, Benjamin

    2012-02-01

    A wide variety of swimmers in nature use body undulations to generate a propulsive force, in part owing to the relative insensitivity of the principle of undulatory swimming to the value of the Reynolds number Re=UL/ν, which measures the relative importance of viscous and inertial forces in the flow considered (U and L being the typical speed and length of the animal, and ν the kinematic viscosity of the surrounding fluid). Here we study a flexible filament forced to oscillate by imposing a harmonic motion to one of its extremities (using magnetic interactions) and propelling itself at the surface of a water tank. This experiment serves as a canonical model for studying the interactions between an elastic structure undergoing complex deformations and the surrounding fluid.

  4. Variational space-time (dis)continuous Galerkin method for nonlinear free surface water waves

    NASA Astrophysics Data System (ADS)

    Gagarina, E.; Ambati, V. R.; van der Vegt, J. J. W.; Bokhove, O.

    2014-10-01

    A new variational finite element method is developed for nonlinear free surface gravity water waves using the potential flow approximation. This method also handles waves generated by a wave maker. Its formulation stems from Miles' variational principle for water waves together with a finite element discretization that is continuous in space and discontinuous in time. One novel feature of this variational finite element approach is that the free surface evolution is variationally dependent on the mesh deformation vis-à-vis the mesh deformation being geometrically dependent on free surface evolution. Another key feature is the use of a variational (dis)continuous Galerkin finite element discretization in time. Moreover, in the absence of a wave maker, it is shown to be equivalent to the second order symplectic Störmer-Verlet time stepping scheme for the free-surface degrees of freedom. These key features add to the stability of the numerical method. Finally, the resulting numerical scheme is verified against nonlinear analytical solutions with long time simulations and validated against experimental measurements of driven wave solutions in a wave basin of the Maritime Research Institute Netherlands.

  5. Effect of Marangoni number on thermocapillary convection and free-surface deformation in liquid bridges

    NASA Astrophysics Data System (ADS)

    Zhang, Yin; Huang, Hu-Lin; Zhou, Xiao-Ming; Zhu, Gui-Ping; Zou, Yong

    2016-04-01

    Floating zone technique is a crucible-free process for growth of high quality single crystals. Unstable thermocapillary convection is a typical phenomenon during the process under microgravity. Therefore, it is very important to investigate the instability of thermocapillary convection in liquid bridges with deformable free-surface under microgravity. In this works, the Volume of Fluid (VOF) method is employed to track the free-surface movement. The results are presented as the behavior of flow structure and temperature distribution of the molten zone. The impact of Marangoni number ( Ma) is also investigated on free-surface deformation as well as the instability of thermocapillary convection. The free-surface exhibits a noticeable axisymmetric (but it is non-centrosymmetric) and elliptical shape along the circumferential direction. This specific surface shape presents a typical narrow `neck-shaped' structure with convex at two ends of the zone and concave at the mid-plane along the axial direction. At both θ = 0° and θ = 90°, the deformation ratio ξ increases rapidly with Ma at first, and then increases slowly. Moreover, the hydrothermal wave number m and the instability of thermocapillary convection increase with Ma.

  6. An experimental investigation of spanwise vortices interacting with solid and free surfaces

    NASA Astrophysics Data System (ADS)

    Donnelly, Martin J.

    Coherent vortices are generated in flow fields due to flow interaction with sharp solid surfaces. Such vortices generate significant disturbances in the flow and affect its further development. In this dissertation attention is focused on the interaction of vortices with solid or free liquid/air surfaces. We examine vortices with their axis parallel or normal to the surface. Three main cases were examined: the interaction of a vortex pair propagating towards a solid boundary, the interaction of spanwise vortices in a turbulent boundary layer, and finally the interaction of spanwise vortices with a flat-plate wake and a free liquid surface. These problems hold significance in several engineering applications, including investigations into trailing wing tip vortices and their interaction with the ground, vortical effects on the development of turbulent boundary layers and free surface signatures and their detection in ship/submarine wakes. Data are acquired with a laser Doppler velocimetry system (LDV) and with Particle-Image Velocimetry (PIV), using a high-speed digital video camera. The LDV system measures two components of velocity along appropriately chosen planes. Grids of data were acquired for different pitch rates of a disturbing flap that generates vortices. Phase-averaged vorticity and turbulence level contours are estimated and presented. It is found that vortices with diameter the order of the boundary layer quickly diffuse and disappear while their turbulent kinetic energy spreads uniformly across the entire boundary layer. Larger vortices have a considerably longer life span and in turn feed more vorticity into the boundary layer. Trailing edge vortices are generated in a water tunnel by sharp hinged motions of a flap. These vortices are allowed to reconnect with the free surface and mix with a turbulent free shear layer. The flow is conditionally sampled via frame grabbing of free surface shadowgraphs. It is found that the vortex core bends away from

  7. Experimental Characterization of Thermo-electric Driven Liquid Lithium Flow in Narrow Trenches for Magnetic Confinement Fusion

    NASA Astrophysics Data System (ADS)

    Xu, Wenyu; Christenson, Michael; Fiflis, Peter; Curreli, Davide; Andruczyk, Daniel; Ruzic, David

    2013-10-01

    The application of liquid metal, especially liquid lithium has become an important topic for plasma facing component (PFC) design. A liquid PFC can effectively eliminate the erosion and thermal stress problems compared to the solid PFC while transferring heat and prolong the lifetime limit of the PFCs. A liquid lithium surface can also suppress the hydrogen isotopes recycling and getter the impurities in fusion reactors. The Lithium/metal infused trench (LiMIT) concept successfully proved that the thermoelectric effect can be utilized to drive liquid lithium flow within horizontally placed metallic open trenches in transverse magnetic field. A limiter based on this concept was tested in HT-7 and gave out positive results. However a broader application of this concept may require the trench be tilted or even placed vertically, for which strong capillary force caused by narrow trenches may be the solution. A new LiMIT design with very narrow trenches have been manufactured and tested in University of Illinois and related results will be presented. Based on this idea new limiters are designed for EAST and LTX and scheduled experiments on both devices will be discussed. This project is supported by DOE/ALPS contract: DEFG02- 99ER54515.

  8. A chemistry and material perspective on lithium redox flow batteries towards high-density electrical energy storage.

    PubMed

    Zhao, Yu; Ding, Yu; Li, Yutao; Peng, Lele; Byon, Hye Ryung; Goodenough, John B; Yu, Guihua

    2015-11-21

    Electrical energy storage system such as secondary batteries is the principle power source for portable electronics, electric vehicles and stationary energy storage. As an emerging battery technology, Li-redox flow batteries inherit the advantageous features of modular design of conventional redox flow batteries and high voltage and energy efficiency of Li-ion batteries, showing great promise as efficient electrical energy storage system in transportation, commercial, and residential applications. The chemistry of lithium redox flow batteries with aqueous or non-aqueous electrolyte enables widened electrochemical potential window thus may provide much greater energy density and efficiency than conventional redox flow batteries based on proton chemistry. This Review summarizes the design rationale, fundamentals and characterization of Li-redox flow batteries from a chemistry and material perspective, with particular emphasis on the new chemistries and materials. The latest advances and associated challenges/opportunities are comprehensively discussed. PMID:26265165

  9. High-flux neutron source based on a liquid-lithium target

    SciTech Connect

    Halfon, S.; Feinberg, G.; Paul, M.; Arenshtam, A.; Berkovits, D.; Kijel, D.; Nagler, A.; Eliyahu, I.; Silverman, I.

    2013-04-19

    A prototype compact Liquid Lithium Target (LiLiT), able to constitute an accelerator-based intense neutron source, was built. The neutron source is intended for nuclear astrophysical research, boron neutron capture therapy (BNCT) in hospitals and material studies for fusion reactors. The LiLiT setup is presently being commissioned at Soreq Nuclear research Center (SNRC). The lithium target will produce neutrons through the {sup 7}Li(p,n){sup 7}Be reaction and it will overcome the major problem of removing the thermal power generated by a high-intensity proton beam, necessary for intense neutron flux for the above applications. The liquid-lithium loop of LiLiT is designed to generate a stable lithium jet at high velocity on a concave supporting wall with free surface toward the incident proton beam (up to 10 kW). During off-line tests, liquid lithium was flown through the loop and generated a stable jet at velocity higher than 5 m/s on the concave supporting wall. The target is now under extensive test program using a high-power electron-gun. Up to 2 kW electron beam was applied on the lithium flow at velocity of 4 m/s without any flow instabilities or excessive evaporation. High-intensity proton beam irradiation will take place at SARAF (Soreq Applied Research Accelerator Facility) superconducting linear accelerator currently in commissioning at SNRC.

  10. High-flux neutron source based on a liquid-lithium target

    NASA Astrophysics Data System (ADS)

    Halfon, S.; Feinberg, G.; Paul, M.; Arenshtam, A.; Berkovits, D.; Kijel, D.; Nagler, A.; Eliyahu, I.; Silverman, I.

    2013-04-01

    A prototype compact Liquid Lithium Target (LiLiT), able to constitute an accelerator-based intense neutron source, was built. The neutron source is intended for nuclear astrophysical research, boron neutron capture therapy (BNCT) in hospitals and material studies for fusion reactors. The LiLiT setup is presently being commissioned at Soreq Nuclear research Center (SNRC). The lithium target will produce neutrons through the 7Li(p,n)7Be reaction and it will overcome the major problem of removing the thermal power generated by a high-intensity proton beam, necessary for intense neutron flux for the above applications. The liquid-lithium loop of LiLiT is designed to generate a stable lithium jet at high velocity on a concave supporting wall with free surface toward the incident proton beam (up to 10 kW). During off-line tests, liquid lithium was flown through the loop and generated a stable jet at velocity higher than 5 m/s on the concave supporting wall. The target is now under extensive test program using a high-power electron-gun. Up to 2 kW electron beam was applied on the lithium flow at velocity of 4 m/s without any flow instabilities or excessive evaporation. High-intensity proton beam irradiation will take place at SARAF (Soreq Applied Research Accelerator Facility) superconducting linear accelerator currently in commissioning at SNRC.

  11. Interfacial sliding near a free surface in a fibrous or layered composite during thermal cycling

    NASA Technical Reports Server (NTRS)

    Cox, B. N.

    1990-01-01

    This paper presents a simple shear lag model of interfacial sliding at a free surface in a layered or continuous fiber composite. The interface is characterized by a critical interfacial shear stress, tau0, which might represent the critical stress for frictional sliding at a weakly bonded interface, or the shear flow stress of a thin ductile interface layer at a well bonded interface. The history, during heating and cooling, of the relative normal displacement of the reinforcing inclusions and the matrix on a free surface cut normal to the inclusions is calculated and shown to depend on both the absolute value and the temperature dependence of tau0, as well as on the magnitudes of the bulk residual stresses. The variety of possible displacement histories suggests that they are a rich source of information about tau0 and the residual stresses.

  12. Boundary condition in liquid thin films revealed through the thermal fluctuations of their free surfaces

    NASA Astrophysics Data System (ADS)

    Pottier, Basile; Talini, Laurence; Frétigny, Christian

    We investigate the properties of liquids confined at nanometric scales from a solid wall with a new noninvasive technique. The optical technique used consists of measuring the height of fluctuations of the free surface, using the reflection of a laser beam on that surface. We hence measure the spontaneous thermal fluctuations of the free surfaces of liquids to probe their hydrodynamic boundary condition at a solid wall. The surface fluctuations of a silicon oil film could be described with a no-slip boundary condition for film thicknesses down to 20 nm. Oppositely, a 4 nm negative slip length had to be introduced to describe the behavior of n-hexadecane, consistently with previous surface force apparatus data on the same system. Our results demonstrate that at vanishing flow, a nanometric solid-like layer close to the wall may exist according to the nature of the liquid. currently at Laboratoire de Physique ENS Lyon.

  13. Numerical Modeling of Free Surface Dynamics of Melt in an Alternate Electromagnetic Field. Part II: Conventional Electromagnetic Levitation

    NASA Astrophysics Data System (ADS)

    Spitans, Sergejs; Baake, Egbert; Nacke, Bernard; Jakovics, Andris

    2016-02-01

    By means of external coupling between electromagnetic (EM) problem in ANSYS and hydrodynamic problem in FLUENT, a numerical model for the liquid metal free surface flow in an alternate EM field has been developed and verified in the first part of the article. Volume of Fluid ( VOF) algorithm has been used for tracking of free surface. In this work, improved performance of the model is presented. General validation of the VOF algorithm is performed by comparison of the calculated free oscillations of the liquid column to its analytical solution. The 3D/ VOF calculation of coupled EM field and free surface flow with Large Eddy Simulation turbulence description for the first time is applied for modeling of conventional EM levitation. Calculation results are compared with 2D/ VOF and 3D/ VOF models that use less precise k- ɛ and k- ω SST turbulence formulations. Obtained time-averaged droplet shapes are used for single-phase flow calculations with different turbulence models and free-slip/no-slip velocity conditions at the fixed free surface for validation of the flow. Meanwhile, series of levitation melting experiments are performed for verification of the simulated droplet shapes. In conclusion, parameter impact on the fully developed flow and the levitated droplet shape is discussed.

  14. Front instability and energy of the free surface

    NASA Astrophysics Data System (ADS)

    Beltrame, Philippe

    2014-05-01

    In recent years, there has been a proliferation of research devoted to the formation of preferential flow paths occurring without macroscopic heterogeneity of the porous media. DiCarlo (2013) points out the connection between "overshoot" and the front instability. Extension of the standard Richards equation is required to capture this phenomenon. In most of the improvements, interfacial phenomena as the triple line at the front are considered. For instance, velocity dependent contact angle (Wang et al., 2013) or contact angle hysteresis (Rätz and Schweizer, 2012) allow to simulate successfully the instability. Another approach proposed by Cueto-Felgueroso and Juanes (2009) introduces a macroscopic surface tension related to the existence of the water/air interface. As previously, the simulation of an advancing front displays physical looking fingering displacements. The goal of this contribution is to better understand the role of the different surface energies in the emergence of the front instability. We propose a model involving both the macroscopic surface tension and the soil wettability. This latter allows to define a contact angle and possibly hysteresis using heterogeneous wettability (Beltrame et al., 2011). Therefore, we employ the phase field approach developed by Felgueroso and Juanes, 2009 to which we add a free energy term corresponding to the wettability: a disjoining or conjoining pressure resulting from effective molecular interactions between the substrate and the free surface (DeGennes, 1985). The difference with the classical suction pressure is the hydrophobic behavior for ultra-thin film (small water saturation). Such a water repellency was recently estimated in the soil (Diamantopoulos et al. 2013). Stability analysis of an advancing front in an uniform porous media shows that macroscopic surface tension and wettability may independently produce the instability growth. In contrast, for a front stopping when reaching the layers interface of

  15. Bubble Bursting at a Free Surface in a Closed Domain

    NASA Astrophysics Data System (ADS)

    Liu, Nian-Nian; Zhang, Shuai; Wang, Shi-Ping

    2016-06-01

    When a charge explodes underwater near a free surface, a bubble would be generated and the surface pushed up very high. Experiments have shown that the motion of the spike lags a lot behind the bubble motion. Many studies only focus on the nonlinear interaction between the bubble and free surface while the water waves afterward is mainly studied based on the linear theory. The nonlinear motion of the water wave after the bubble pulsation is seldom studied. In this study, we concerns the interaction between underwater explosion generated bubble and a free surface and its bursting at a free surface in a closed domain. Suppose that the fluid outside the bubble is incompressible, non-viscous and irrotational and the velocity potential satisfies the Laplace equation. Boundary integral method is used to solve the Laplace equation for the velocity potential. The bubble content is described by an adiabatic law. The whole process of the bubble motion and subsequently the water wave propagation will be simulated in this paper. Particular attention will be focused on the phenomenon of water wave propagation in a closed domain.

  16. Measuring flow and pressure of lithium coolant under developmental testing of a high-temperature cooling system of a space nuclear power plant

    NASA Astrophysics Data System (ADS)

    Sobolev, V. Ya.; Sinyavsky, V. V.

    2014-12-01

    Sub-megawatt space NPP use lithium as a coolant and niobium alloy as a structural material. In order to refine the lithium-niobium technology of the material and design engineering, lithium-niobium loops were worked out in RSC Energia, and they were tested at a working temperature of lithium equal to 1070-1300 K. In order to measure the lithium flow and pressure, special gauges were developed, which made possible the calibration and checkout of the loops without their dismantling. The paper describes the architecture of the electromagnetic flowmeter and the electromagnetic vibrating-wire pressure transducer (gauge) for lithium coolant in the nuclear power plant cooling systems. The operating principles of these meters are presented. Flowmeters have been developed for channel diameters ranging from 10 to 100 mm, which are capable of measuring lithium flows in the range of 0.1 to 30 L/s with the error of 3% for design calibration and 1% for volume graduation. The temperature error of the pressure transducers does not exceed 0.4% per 100 K; the nonlinearity and hysteresis of the calibration curve do not exceed 0.3 and 0.4%, respectively. The transducer applications are illustrated by the examples of results obtained from tests on the NPP module mockup and heat pipes of a radiation cooler.

  17. Passive manipulation of free-surface instability by deformable solid bilayers.

    PubMed

    Sahu, Shivam; Shankar, V

    2016-07-01

    This study deals with the elastohydrodynamic coupling that occurs in the flow of a liquid layer down an inclined plane lined with a deformable solid bilayer and its consequences on the stability of the free surface of the liquid layer. The fluid is Newtonian and incompressible, while the linear elastic constitutive relation has been considered for the deformable solid bilayer, and the densities of the fluid and the two solids are kept equal. A temporal linear stability analysis is carried out for this coupled solid-fluid system. A long-wave asymptotic analysis is employed to obtain an analytical expression for the complex wavespeed in the low wave-number regime, and a numerical shooting method is used to solve the coupled set of governing differential equations in order to obtain the stability criterion for arbitrary values of the wave number. In a previous work on plane Couette flow past an elastic bilayer, Neelmegam et al. [Phys. Rev. E 90, 043004 (2014)PLEEE81539-375510.1103/PhysRevE.90.043004] showed that the instability of the flow can be significantly influenced by the nature of the solid layer, which is adjacent to the liquid layer. In stark contrast, for free-surface flow past a bilayer, our long-wave asymptotic analysis demonstrates that the stability of the free-surface mode is insensitive to the nature of the solid adjacent to the liquid layer. Instead, it is the effective shear modulus of the bilayer G_{eff} (given by H/G_{eff}=H_{1}/G_{1}+H_{2}/G_{2}, where H=H_{1}+H_{2} is the total thickness of the solid bilayer, H_{1} and H_{2} are the thicknesses of the two solid layers, and G_{1} and G_{2} are the shear moduli of the two solid layers) that determines the stability of the free surface in the long-wave limit. We show that for a given Reynolds number, the free-surface instability is stabilized when G_{eff} decreases below a critical value. At finite wave numbers, our numerical solution indicates that additional instabilities at the free surface and

  18. Passive manipulation of free-surface instability by deformable solid bilayers

    NASA Astrophysics Data System (ADS)

    Sahu, Shivam; Shankar, V.

    2016-07-01

    This study deals with the elastohydrodynamic coupling that occurs in the flow of a liquid layer down an inclined plane lined with a deformable solid bilayer and its consequences on the stability of the free surface of the liquid layer. The fluid is Newtonian and incompressible, while the linear elastic constitutive relation has been considered for the deformable solid bilayer, and the densities of the fluid and the two solids are kept equal. A temporal linear stability analysis is carried out for this coupled solid-fluid system. A long-wave asymptotic analysis is employed to obtain an analytical expression for the complex wavespeed in the low wave-number regime, and a numerical shooting method is used to solve the coupled set of governing differential equations in order to obtain the stability criterion for arbitrary values of the wave number. In a previous work on plane Couette flow past an elastic bilayer, Neelmegam et al. [Phys. Rev. E 90, 043004 (2014), 10.1103/PhysRevE.90.043004] showed that the instability of the flow can be significantly influenced by the nature of the solid layer, which is adjacent to the liquid layer. In stark contrast, for free-surface flow past a bilayer, our long-wave asymptotic analysis demonstrates that the stability of the free-surface mode is insensitive to the nature of the solid adjacent to the liquid layer. Instead, it is the effective shear modulus of the bilayer Geff (given by H /Geff=H1/G1+H2/G2 , where H =H1+H2 is the total thickness of the solid bilayer, H1 and H2 are the thicknesses of the two solid layers, and G1 and G2 are the shear moduli of the two solid layers) that determines the stability of the free surface in the long-wave limit. We show that for a given Reynolds number, the free-surface instability is stabilized when Geff decreases below a critical value. At finite wave numbers, our numerical solution indicates that additional instabilities at the free surface and the liquid-solid interface can be induced by wall

  19. Experimental investigation of a free-surface turbulent jet with Coanda effect

    NASA Astrophysics Data System (ADS)

    Miozzi, M.; Lalli, F.; Romano, G. P.

    2010-07-01

    The deviation of a jet from the straight direction due to the presence of a lateral wall is investigated from the experimental point of view. This flow condition is known as Coanda jet (from the Romanian aerodynamicist Henry Marie Coanda who discovered and applied it at the beginning of XXth century) or offset jet. The objective of the work is to detail the underlying mechanisms of such a phenomenon aiming to use it as a flow control method at polluted river flows mouth. To do this, a large laboratory free-surface tank with an incoming channel has been set up and velocity field measurements are performed by Optical Flow methods (namely Feature Tracking). Preliminary tests on the well-known free jet configuration without any marine structure ( i.e. lateral wall) are performed to allow comparison with free jet scaling and self-similar solutions. The presence of the free-surface gives rise to centerline velocity decay which is lower than in free unbounded plane or circular jets due to the vertically limited ambient fluid entrainment. In the second part of the paper, the effect of a lateral wall on the jet configuration is examined by placing it at different lateral distances from the jet outlet. The resulting velocity fields clearly show an inclined Coanda jet with details which seems to depend on the lateral wall distance itself. The analysis of self-similarity along the inclined jet direction reveals that for wall distances larger than 5 jet widths this dependence almost disappears.

  20. Investigating Free-surface, MHD Instabilities in Liquid Metals

    NASA Astrophysics Data System (ADS)

    Brumfiel, Geoff; Ji, Hantao; Zweben, Stewart

    1999-11-01

    The addition of the Lorentz force (j × B) to MHD fluids, such as liquid metals, could introduce new instabilities to free-surface motions. An experiment is under development at PPPL that will contribute to the understanding of these instabilities. This experiment is designed to explore how instabilities form and propagate on the surface of liquid metals. Metals with low melting points and reasonable conductive properties (such as Ga) are melted in an eight inch, square Pyrex container. The container is placed in a large magnetic field (up to 5 kG) and a perpendicular current is set up in the metal. Waves are generated using a simple wave driving apparatus. A one dimensional, diode camera is used to monitor wave propagation perpendicular to the B-field. Initial results will be presented and discussed. This experiment will provide information that could eventually be used to better control free-surface motions in liquid Li walls in fusion reactors.

  1. Free surface oscillations of liquid hydrogen in microgravity conditions

    NASA Astrophysics Data System (ADS)

    Schmitt, Sebastian; Dreyer, Michael E.

    2015-12-01

    Experiments were performed to investigate the reorientation behavior and axial sloshing of liquid parahydrogen in a partly filled right circular cylinder due to a step reduction of gravity. Different temperature gradients along the cylinder wall in vertical direction were imposed to examine the influence of a wall superheat on the free surface. Experiments were conducted in the drop tower at the University of Bremen which provides a microgravity time of 4.7 s and a compensated gravity environment of 10-6g0 (acceleration due to gravity). The thermal preparation of the experiments allowed to create defined wall temperature gradients and a stratified or homogenous liquid temperature distribution. Several sensors along the cylinder wall and in the vapor region monitored the temperature. The pressure inside the experiment was recorded and visual access was enabled by an endoscope. The experiments showed that the wall superheat has an influence on the free surface as well as on the temperature and pressure evolutions.

  2. Reduced Viscosity of Free Surface in Entangled Polymer Melt Films

    NASA Astrophysics Data System (ADS)

    Koga, Tad; Li, C.; Endoh, M.; Koo, J.; Rafailovich, M.; Narayanan, S.; Lee, D.; Lurio, L.; Sinha, S.

    2010-03-01

    The dynamics of polymer chains near the surface of a melt and within thin films remains a subject of inquiry along with the nature of the glass transition in these systems. By embedding ``dilute'' gold nanoparticles in single polystyrene thin films as ``markers'', we could probe the local viscosity of the free surface at temperatures far above the glass transition temperature (Tg). The technique used was X-ray photon correlation spectroscopy with resonance-enhanced X-ray scattering. The results clearly showed the viscosity was about 30 % lower than the rest of the film. We found that this reduction is strongly associated with chain entanglements at the free surface rather than the reduction in Tg.

  3. Boundary Condition in Liquid Thin Films Revealed through the Thermal Fluctuations of Their Free Surfaces

    NASA Astrophysics Data System (ADS)

    Pottier, B.; Frétigny, C.; Talini, L.

    2015-06-01

    We investigate the properties of nanometric liquid films with a new noninvasive technique. We measure the spontaneous thermal fluctuations of the free surfaces of liquids to probe their hydrodynamic boundary condition at a solid wall. The surface fluctuations of a silicon oil film could be described with a no-slip boundary condition for film thicknesses down to 20 nm. Oppositely, a 4 nm negative slip length had to be introduced to describe the behavior of n -hexadecane, consistently with previous surface force apparatus data on the same system. Our results demonstrate that at vanishing flow a nanometric solidlike layer close to the wall may exist according to the nature of the liquid.

  4. Large-eddy simulation of free-surface decaying turbulence with dynamic subgrid-scale models

    NASA Astrophysics Data System (ADS)

    Salvetti, M. V.; Zang, Y.; Street, R. L.; Banerjee, S.

    1997-08-01

    This paper describes large-eddy simulations of decaying turbulence in an open channel, using different dynamic subgrade-scale models, viz. the dynamic model of Germano et al. [Phys. Fluids A 3, 1790 (1991)] (DSM), the dynamic mixed model in Zang et al. [Phys. Fluids A 5, 3186 (1993)] (DMM), and the dynamic two-parameter model of Salvetti and Banerjee [Phys. Fluids 7, 2831 (1995)] (DTM). These models are incorporated in a finite-volume solver of the Navier-Stokes equations. A direct numerical simulation of this flow conducted by Pan and Banerjee [Phys. Fluids 7, 1649 (1995)] showed that near the free surface turbulence has a quasi-two-dimensional behavior. Moreover, the quasi-two-dimensional region increases in thickness with the decay time, although the structure remains three-dimensional in the central regions of the flow. The results of the large-eddy simulations show that both the DMM and the DTM are able to reproduce the features of the decay process observed in the direct simulation and to handle the anisotropic nature of the flow. Nevertheless, the addition of the second model coefficient in the DTM improves the agreement with the direct simulation. When the DSM is used, significant discrepancies are observed between the large-eddy and the direct simulations during the decay process at the free surface.

  5. Numerical modeling of the effects of a free surface on the operating characteristics of Marine Hydrokinetic Turbines

    NASA Astrophysics Data System (ADS)

    Adamski, Samantha; Aliseda, Alberto

    2012-11-01

    Marine Hydrokinetic (MHK) turbines are a growing area of research in the renewable energy field because tidal currents are a highly predictable clean energy source. The presence of a free surface may influence the flow around the turbine and in the wake, critically affecting turbine performance and environmental effects through modification of wake physical variables. The characteristic Froude number that control these processes is still a matter of controversy, with the channel depth and turbine's depth, blade tip depth and diameter as potential candidates for a length scale used in literature. We use the Volume of Fluid model to track the free surface dynamics in a RANS simulation with a BEMT model of the turbine to understand the physics of the wake-free surface interactions. Pressure and flow rate boundary conditions for channel's inlet, outlet and air side have been tested in an effort to determine the optimum set of simulation conditions for MHK turbines in rivers or estuaries. Stability and accuracy in terms of power extraction and kinetic and potential energy budgets are considered. The goal of this research is to determine, quantitatively in non dimensional parameter space, the limit between negligible and significant free surface effects on MHK turbine analysis. Supported by DOE through the National Northwest Marine Renewable Energy Center.

  6. Vortical and nonlinear effects in the roll motion of a 2-D body in the free surface investigated by SPH

    NASA Astrophysics Data System (ADS)

    Olmez, O.; Ozbulut, M.; Yildiz, M.; Goren, O.

    2016-06-01

    The present study investigates the vortical and nonlinear effects in the roll motion of a 2-D body with square cross-sections by using Smoothed Particle Hydrodynamics (SPH). A 2-D rigid body with square cross-section is taken into account for the benchmark study and subjected to the oscillatory roll motion with a given angular frequency. The governing equations are continuity equation and Euler's equation with artificial viscosity term. Weakly Compressible SPH (WCSPH) scheme is employed for the discretization of the governing equations. Velocities of the fluid particles are updated by means of XSPH+Artificial Particle Displacement (VXSPH+APD) algorithm. In this method only the free surface fluid particles are subjected to VXSPH algorithm while the APD algorithm is employed for the fully populated flow regions. The hybrid usage of numerical treatment keeps free surface particles together by creating an artificial surface tension on the free surface. VXSPH+APD is a proven numerical treatment to provide the most accurate results for this type of free surface flows (Ozbulut et al. 2014). The results of the present study are compared with those of the experimental studies as well as with those of the numerical methods obtained from the current literature.

  7. Preliminary corrosion studies of P-91 in flowing lead-lithium with and without magnetic field for Indian lead-lithium ceramic breeder test blanket module

    NASA Astrophysics Data System (ADS)

    Sarada Sree, Atchutuni; Tanaji, Kamble; Poulami, Chakraborty; Fotedar, R. K.; Rajendra Kumar, E.; Suri, A. K.; Platacis, E.; Ziks, A.; Bucenieks, I.; Poznjaks, A.; Shisko, A.

    2014-08-01

    To study the corrosion of P-91 (9% chromium and 1% molybdenum) material with lead-lithium (Pb-Li) eutectic, two experiments were carried out in a forced convection loop, at eutectic temperature of 550 °C. The first experiment was carried out at a velocity of 15 cm s-1 for 1000 h and the second experiment, at a velocity of 30 cm s-1 for 2700 h. In both the experiments, P-91 sample coupons were exposed to Pb-Li flow in the presence and absence of magnetic field. Samples were analyzed using an optical microscope, scanning electron microscope (SEM) and electron probe micro-analyzer (EPMA). Micro-Vickers hardness testing was also carried out. Dissolution of elements into liquid metal is the main corrosion mechanism. Iron and chromium were selectively getting leached out from the near-surface region (˜4 µm) in the first experiment and molybdenum and manganese were also found leaching from a greater depth in the second experiment. The samples kept in the magnetic field showed a higher corrosion rate (˜320 µm/year) as compared with the corrosion rate (˜200 µm/year) of the samples kept in non-magnetic field regions. Hardness of the exposed samples was lower than the unexposed samples in both the experiments. Hardness was found to be low in the near-surface region for all the samples in both the experiments.

  8. Free Surface Wave Interaction with a Horizontal Cylinder

    NASA Astrophysics Data System (ADS)

    Oshkai, P.; Rockwell, D.

    1999-10-01

    Classes of vortex formation from a horizontal cylinder adjacent to an undulating free-surface wave are characterized using high-image-density particle image velocimetry. Instantaneous representations of the velocity field, streamline topology and vorticity patterns yield insight into the origin of unsteady loading of the cylinder. For sufficiently deep submergence of the cylinder, the orbital nature of the wave motion results in multiple sites of vortex development, i.e., onset of vorticity concentrations, along the surface of the cylinder, followed by distinctive types of shedding from the cylinder. All of these concentrations of vorticity then exhibit orbital motion about the cylinder. Their contributions to the instantaneous values of the force coefficients are assessed by calculating moments of vorticity. It is shown that large contributions to the moments and their rate of change with time can occur for those vorticity concentrations having relatively small amplitude orbital trajectories. In a limiting case, collision with the surface of the cylinder can occur. Such vortex-cylinder interactions exhibit abrupt changes in the streamline topology during the wave cycle, including abrupt switching of the location of saddle points in the wave. The effect of nominal depth of submergence of the cylinder is characterized in terms of the time history of patterns of vorticity generated from the cylinder and the free surface. Generally speaking, generic types of vorticity concentrations are formed from the cylinder during the cycle of the wave motion for all values of submergence. The proximity of the free surface, however, can exert a remarkable influence on the initial formation, the eventual strength, and the subsequent motion of concentrations of vorticity. For sufficiently shallow submergence, large-scale vortex formation from the upper surface of the cylinder is inhibited and, in contrast, that from the lower surface of the cylinder is intensified. Moreover

  9. Micromechanics of slip bands on a free surface

    NASA Technical Reports Server (NTRS)

    Lin, S. R.; Lin, T. H.

    1976-01-01

    A micromechanics analysis for the formation and propagation of slip bands on the free surface of a polycrystal under monotonic loading is presented. For the growth of slip bands, the analysis satisfies the conditions of both equilibrium and displacement continuity, as well as the relation between slip and the resolved shear stress throughout the polycrystal. Numerical calculations show how the microstress field causes the concentration of plastic deformation in discrete sliding bands and give results which are in good qualitative agreement with known slip band observations on aluminum single crystals.

  10. The motion of elliptic cylinder under free surface

    NASA Astrophysics Data System (ADS)

    Kostikov, V. K.; Makarenko, N. I.

    2016-06-01

    A problem on generation of unsteady nonlinear waves on the surface of an infinitely deep ideal fluid due to the motion of a submerged elliptical cylinder is considered. It is supposed that the cylinder can rotate in addition to translational two-dimensional motion. The initial formulation of the problem is reduced to an integrodifferential system of equations for the functions defining the free surface shape, the normal and tangential components of velocity on the free boundary. The small-time asymptotics of the solution is constructed in the case of the cylinder that moves with a constant acceleration from rest.

  11. Study on Applicability of Numerical Simulation to Evaluation of Gas Entrainment From Free Surface

    SciTech Connect

    Kei Ito; Takaaki Sakai; Hiroyuki Ohshima

    2006-07-01

    An onset condition of gas entrainment (GE) due to free surface vortex has been studied to establish a design of fast breeder reactor with higher coolant velocity than conventional designs, because the GE might cause the reactor operation instability and therefore should be avoided. The onset condition of the GE has been investigated experimentally and theoretically, however, dependency of the vortex type GE on local geometry configuration of each experimental system and local velocity distribution has prevented researchers from formulating the universal onset condition of the vortex type GE. A real scale test is considered as an accurate method to evaluate the occurrence of the vortex type GE, but the real scale test is generally expensive and not useful in the design study of large and complicated FBR systems, because frequent displacement of inner equipments accompanied by the design change is difficult in the real scale test. Numerical simulation seems to be promising method as an alternative to the real scale test. In this research, to evaluate the applicability of the numerical simulation to the design work, numerical simulations were conducted on the basic experimental system of the vortex type GE. This basic experiment consisted of rectangular flow channel and two important equipments for vortex type GE in the channel, i.e. vortex generation and suction equipments. Generated vortex grew rapidly interacting with the suction flow and the grown vortex formed a free surface dent (gas core). When the tip of the gas core or the bubbles detached from the tip of the gas core reached the suction mouth, the gas was entrained to the suction tube. The results of numerical simulation under the experimental conditions were compared to the experiment in terms of velocity distributions and free surface shape. As a result, the numerical simulation showed qualitatively good agreement with experimental data. The numerical simulation results were similar to the experimental

  12. Plankton dynamics in thermally-stratified free-surface turbulence

    NASA Astrophysics Data System (ADS)

    Lovecchio, Salvatore; Soldati, Alfredo

    2015-11-01

    Thermal stratification induced by solar heating near the ocean-atmosphere interface influences the transfer fluxes of heat, momentum and chemical species across the interface. Due to thermal stratification, a region of large temperature gradients (thermocline) may form with strong consequences for the marine ecosystem. In particular, the thermocline is believed to prevent phytoplankton from reaching the well-lit surface layer, where they can grow through the process of photosynthesis. In this paper, we use a DNS-based Eulerian-Lagrangian approach to examine the role of stratification on phytoplankton dynamics in thermally-stratified free-surface turbulence. We focus on gyrotactic self-propelled phytoplankton cells, considering different stratification levels (quantified by the Richardson number) and different gyro tactic re-orientation times. We show that the modulation of turbulent fluctuations induced by stable stratification has a strong effect on the orientation and distribution of phytoplankton, possibly leading to trapping of some species within the thermocline. Specifically, we observe the appearance of a depletion layer just below the free-surface as stratification increases, accompanied by a reduction in the vertical stability of phytoplankton cells.

  13. Free surface BCP self-assembly process characterization with CDSEM

    NASA Astrophysics Data System (ADS)

    Levi, Shimon; Weinberg, Yakov; Adan, Ofer; Klinov, Michael; Argoud, Maxime; Claveau, Guillaume; Tiron, Raluca

    2016-03-01

    A simple and common practice to evaluate Block copolymers (BCP) self-assembly performances, is on a free surface wafer. With no guiding pattern the BCP designed to form line space pattern for example, spontaneously rearranges to form a random fingerprint type of a pattern. The nature of the rearrangement is dictated by the physical properties of the BCP moieties, wafer surface treatment and the self-assembly process parameters. Traditional CDSEM metrology algorithms are designed to measure pattern with predefined structure, like linespace or oval via holes. Measurement of pattern with expected geometry can reduce measurement uncertainty. Fingerprint type of structure explored in this dissertation, poses a challenge for CD-SEM measurement uncertainty and offers an opportunity to explore 2D metrology capabilities. To measure this fingerprints we developed a new metrology approach that combines image segmentation and edge detection to measure 2D pattern with arbitrary rearrangement. The segmentation approach enabled to quantify the quality of the BCP material and process, detecting 2D attributes such as: CD and CDU at one axis, and number of intersections, length and number of PS fragments, etched PMMA spaces and donut shapes numbers on the second axis. In this paper we propose a 2D metrology to measure arbitrary BCP pattern on a free surface wafer. We demonstrate experimental results demonstrating precision data, and characterization of PS-b-PMMA BCP, intrinsic period L0 = 38nm (Arkema), processed at different bake time and temperatures.

  14. Magnetic gauge for free surface velocities due to rock blasts

    NASA Astrophysics Data System (ADS)

    Ashuach, Yecheskel; Gissis, Itai; Avinadav, Chen

    2013-06-01

    We developed a simple magnetic gauge for measuring free surface velocities of rock materials in the range of 0.1-20 m/s. The gauge consists of two elements: a NdFeB magnet and a pick-up coil. The coil is attached to the free surface at the point of interest. The magnet is placed a few centimeters away from the coil on its central axis, intact from the rock. Rock surface movement due to blast loading induces current in the coil due to change of the magnetic flux. The coil velocity is deduced from the measured current using a computational code. The gauge was tested and validated in a set of free-falling experiments. We present velocity measurements from various blast experiments in limestone and reinforced concrete, using both the magnetic gauge and a Doppler interferometer. The results obtained from the two measurement techniques were in good agreement during a few milliseconds. The magnetic gauge is cheap and very simple to operate, and therefore favorable for mapping the velocity distribution at multiple points of interest on the surface.

  15. Mathematical and computational studies of equilibrium capillary free surfaces

    NASA Technical Reports Server (NTRS)

    Albright, N.; Chen, N. F.; Concus, P.; Finn, R.

    1977-01-01

    The results of several independent studies are presented. The general question is considered of whether a wetting liquid always rises higher in a small capillary tube than in a larger one, when both are dipped vertically into an infinite reservoir. An analytical investigation is initiated to determine the qualitative behavior of the family of solutions of the equilibrium capillary free-surface equation that correspond to rotationally symmetric pendent liquid drops and the relationship of these solutions to the singular solution, which corresponds to an infinite spike of liquid extending downward to infinity. The block successive overrelaxation-Newton method and the generalized conjugate gradient method are investigated for solving the capillary equation on a uniform square mesh in a square domain, including the case for which the solution is unbounded at the corners. Capillary surfaces are calculated on the ellipse, on a circle with reentrant notches, and on other irregularly shaped domains using JASON, a general purpose program for solving nonlinear elliptic equations on a nonuniform quadrilaterial mesh. Analytical estimates for the nonexistence of solutions of the equilibrium capillary free-surface equation on the ellipse in zero gravity are evaluated.

  16. Review of free-surface MHD experiments and modeling.

    SciTech Connect

    Molokov, S.; Reed, C. B.

    2000-06-02

    This review paper was prepared to survey the present status of analytical and experimental work in the area of free surface MHD and thus provide a well informed starting point for further work by the Advanced Limiter-diverter Plasma-facing Systems (ALPS) program. ALPS were initiated to evaluate the potential for improved performance and lifetime for plasma-facing systems. The main goal of the program is to demonstrate the advantages of advanced limiter/diverter systems over conventional systems in terms of power density capability, component lifetime, and power conversion efficiency, while providing for safe operation and minimizing impurity concerns for the plasma. Most of the work to date has been applied to free surface liquids. A multi-disciplinary team from several institutions has been organized to address the key issues associated with these systems. The main performance goals for advanced limiters and diverters are a peak heat flux of >50 MW/m{sup 2}, elimination of a lifetime limit for erosion, and the ability to extract useful heat at high power conversion efficiency ({approximately}40%). The evaluation of various options is being conducted through a combination of laboratory experiments, modeling of key processes, and conceptual design studies.

  17. 46 CFR 170.290 - Free surface correction for damage stability calculations.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Free surface correction for damage stability...) SUBDIVISION AND STABILITY STABILITY REQUIREMENTS FOR ALL INSPECTED VESSELS Free Surface § 170.290 Free surface correction for damage stability calculations. (a) When doing the damage stability calculations required...

  18. Material and Energy Flows in the Materials Production, Assembly, and End-of-Life Stages of the Automotive Lithium-Ion Battery Life Cycle

    SciTech Connect

    Dunn, Jennifer B.; Gaines, Linda; Barnes, Matthew; Sullivan, John L.; Wang, Michael

    2014-01-01

    This document contains material and energy flows for lithium-ion batteries with an active cathode material of lithium manganese oxide (LiMn₂O₄). These data are incorporated into Argonne National Laboratory’s Greenhouse gases, Regulated Emissions, and Energy use in Transportation (GREET) model, replacing previous data for lithium-ion batteries that are based on a nickel/cobalt/manganese (Ni/Co/Mn) cathode chemistry. To identify and determine the mass of lithium-ion battery components, we modeled batteries with LiMn₂O₄ as the cathode material using Argonne’s Battery Performance and Cost (BatPaC) model for hybrid electric vehicles, plug-in hybrid electric vehicles, and electric vehicles. As input for GREET, we developed new or updated data for the cathode material and the following materials that are included in its supply chain: soda ash, lime, petroleum-derived ethanol, lithium brine, and lithium carbonate. Also as input to GREET, we calculated new emission factors for equipment (kilns, dryers, and calciners) that were not previously included in the model and developed new material and energy flows for the battery electrolyte, binder, and binder solvent. Finally, we revised the data included in GREET for graphite (the anode active material), battery electronics, and battery assembly. For the first time, we incorporated energy and material flows for battery recycling into GREET, considering four battery recycling processes: pyrometallurgical, hydrometallurgical, intermediate physical, and direct physical. Opportunities for future research include considering alternative battery chemistries and battery packaging. As battery assembly and recycling technologies develop, staying up to date with them will be critical to understanding the energy, materials, and emissions burdens associated with batteries.

  19. Material and energy flows in the materials production, assembly, and end-of-life stages of the automotive lithium-ion battery life cycle

    SciTech Connect

    Dunn, J.B.; Gaines, L.; Barnes, M.; Wang, M.; Sullivan, J.

    2012-06-21

    This document contains material and energy flows for lithium-ion batteries with an active cathode material of lithium manganese oxide (LiMn{sub 2}O{sub 4}). These data are incorporated into Argonne National Laboratory's Greenhouse gases, Regulated Emissions, and Energy use in Transportation (GREET) model, replacing previous data for lithium-ion batteries that are based on a nickel/cobalt/manganese (Ni/Co/Mn) cathode chemistry. To identify and determine the mass of lithium-ion battery components, we modeled batteries with LiMn{sub 2}O{sub 4} as the cathode material using Argonne's Battery Performance and Cost (BatPaC) model for hybrid electric vehicles, plug-in hybrid electric vehicles, and electric vehicles. As input for GREET, we developed new or updated data for the cathode material and the following materials that are included in its supply chain: soda ash, lime, petroleum-derived ethanol, lithium brine, and lithium carbonate. Also as input to GREET, we calculated new emission factors for equipment (kilns, dryers, and calciners) that were not previously included in the model and developed new material and energy flows for the battery electrolyte, binder, and binder solvent. Finally, we revised the data included in GREET for graphite (the anode active material), battery electronics, and battery assembly. For the first time, we incorporated energy and material flows for battery recycling into GREET, considering four battery recycling processes: pyrometallurgical, hydrometallurgical, intermediate physical, and direct physical. Opportunities for future research include considering alternative battery chemistries and battery packaging. As battery assembly and recycling technologies develop, staying up to date with them will be critical to understanding the energy, materials, and emissions burdens associated with batteries.

  20. Self-induced sloshing caused by an upward round jet impinging on the free surface

    SciTech Connect

    Madarame, Haruki; Okamoto, Koji; Iida, Masao

    1995-11-01

    The demand for compact design of FBR made it necessary to study the interaction between high speed coolant flow and the free surface. Self-induced sloshing was found to occur with an upward round jet making a surface swell at the impinging point. The conditions under which the sloshing occurred were investigated experimentally together with the sloshing modes and frequencies. Without exception the induced mode had only one diametrical node, which was accompanied by the lateral motion of the swell. The mode was replaced by lower one with increasing the inlet-surface distance and the velocity, the reason of which was explained by the following assumption; the oscillation of water columns on both sides of the jet connected by a virtual cross flow through the jet, i.e., jet-flutter, was coupled with the sloshing and supplied energy to it.

  1. Free surface microfluidic/SERS for detection of gas-phase DNT

    NASA Astrophysics Data System (ADS)

    Piorek, Brian D.; Lee, Seung Joon; Judy, Nick; Meinhart, Carl D.; Moskovits, Martin; Fountain, Augustus; Christesen, Steven; Guicheteau, Jason

    2010-04-01

    A novel microfluidic/SERS platform has been developed for real time sensing of 2,4-DNT. The fundamental research is being conducted at UCSB, commercialized by SpectraFluidics, and validated at ECBC. The system leverages phenomena at multiple length scales, ranging from tens of micrometers to several nanometers. The key enabling technology is a newly developed invention termed Free-Surface Fluidics (FSF), where one or more fluidic surfaces are confined by surface tension forces, and exposed to the surrounding atmosphere. The free-surface fluidic architecture is combined with surface-enhanced Raman spectroscopy (SERS) for detection of 2,4-DNT. Once 2,4-DNT analyte molecules are absorbed into the flow, they can interact with gold or silver colloidal particles. This architecture allows for analysis and deterministic control of SERS 'hot spot' aggregation, which can increase Raman scattering signal strength by up to 10 orders in magnitude. We have successfully measured DNT vapor at concentrations as low as ~1 ppb. This sensitivity value is confirmed by orthogonal measurements using GC-mass spectroscopy at ECBC.

  2. Modeling Outburst Flooding as a Turbulent Hydraulic Fracture Parallel to a Nearby Free Surface

    NASA Astrophysics Data System (ADS)

    Tsai, V. C.; Rice, J. R.

    2009-12-01

    Meltwater generated at the surface and base of glaciers and ice sheets is known to have a large impact on how ice masses behave dynamically, but much is still unknown about the physical processes responsible for how this meltwater drains out of the glacier. For example, little attention has been paid to short-timescale processes like turbulent hydraulic fracture, which is likely an important mechanism by which drainage channels initially form when water pressures are high. In recent work (Tsai and Rice [Fall AGU, 2008; JGR subm., 2009]), we have constructed a model of this turbulent hydraulic fracture process in which over-pressurized water is assumed to flow turbulently through a crack, leading to crack growth. However, one important limitation of this prior work is that it only strictly applies in the limit of short crack length 2L compared to glacier height H, whereas relevant observations of supraglacial lake drainage, jokulhlaups and sub-glacial lake-to-lake transport episodes do not fall in this regime. Here, we improve somewhat upon this model by explicitly accounting for a nearby free surface. We accomplish this by applying the approach of Erdogan et al. [Meth. Anal. Sol. Crack Prob., 1973] to numerically calculate elastic displacements consistent with crack pressure distribution for a crack near a free surface, and use these results as before to simultaneously satisfy the governing fluid, elastic and fracture equations. Our results are analogous to the zero fracture toughness results of Zhang et al. [Int. J. Numer. Anal. Meth. Geomech., 2005], but applied to the case of turbulent flow rather than laminar flow of a Newtonian viscous fluid. Our new results clarify the importance of the free surface and potentially explain discrepancies between our previous modeling results and observations of supraglacial lake drainage by Das et al. [Science, 2008]. However, the numerical challenges increase as 2L becomes comparable to or much larger than H. We hope to

  3. Modeling Outburst Flooding as a Turbulent Hydraulic Fracture Parallel to a Nearby Free Surface

    NASA Astrophysics Data System (ADS)

    Tsai, Victor; Rice, James

    2010-05-01

    Meltwater generated at the surface and base of glaciers and ice sheets is known to have a large impact on how ice masses behave dynamically, but much is still unknown about the physical processes responsible for how this meltwater drains out of the glacier. For example, little attention has been paid to short-timescale processes like turbulent hydraulic fracture, which is likely an important mechanism by which drainage channels initially form when water pressures are high. In recent work (Tsai and Rice [Fall AGU, 2008; JGR subm., 2009]), we have constructed a model of this turbulent hydraulic fracture process in which over-pressurized water is assumed to flow turbulently through a crack, leading to crack growth. However, one important limitation of this prior work is that it only strictly applies in the limit of short crack length, 2L, compared to glacier height, H, whereas relevant observations of supraglacial lake drainage, jokulhlaups and sub-glacial lake-to-lake transport episodes do not fall in this regime. Here, we improve somewhat upon this model by explicitly accounting for a nearby free surface. We accomplish this by applying the approach of Erdogan et al. [Meth. Anal. Sol. Crack Prob., 1973] to numerically calculate elastic displacements consistent with crack pressure distribution for a crack near a free surface, and use these results as before to simultaneously satisfy the governing fluid, elastic and fracture equations. Our results are analogous to the zero fracture toughness results of Zhang et al. [Int. J. Numer. Anal. Meth. Geomech., 2005], but applied to the case of turbulent flow rather than laminar flow of a Newtonian viscous fluid. Our new results clarify the importance of the free surface and potentially explain discrepancies between our previous modeling results and observations of supraglacial lake drainage by Das et al. [Science, 2008]. However, the numerical challenges increase as 2L becomes comparable to or much larger than H. We hope to

  4. Recent Advances in Applicability of TEMHD Driven Liquid Lithium as a Fusion Relevant PFC

    NASA Astrophysics Data System (ADS)

    Szott, Matthew; Fiflis, Peter; Kalathiparambil, Kishor; Ruzic, David N.

    2015-11-01

    Liquid lithium displays increasing promise as a replacement to solid plasma facing components (PFC) in fusion device applications. Liquid PFCs reduce erosion and thermal stress damage, prolonging device lifetime, while lithium has been shown to decrease edge recycling, reduce impurities, and enhance plasma performance. The Liquid Metal Infused Trench (LiMIT) concept developed at UIUC successfully demonstrates horizontal and vertical thermoelectric magnetohydrodynamic (TEMHD) flow of liquid lithium through metal trenches for use as a PFC. Installed in the HT-7 tokamak and at the Magnum-PSI linear plasma device, the system performed effectively in fusion relevant conditions. In high heat flux tests, trench dry-out was observed, which exposes solid trench material due to higher TEMHD force on the area with the highest heat flux. A 3D free surface fluid model of dry-out and experimental tests conducted to mitigate the detrimental effect are described. The final designs for the upcoming test of LiMIT as a limiter for the EAST tokamak are discussed, along with velocity characteristics of steady-state TEMHD driven flow through the LiMIT system inclined up to 180 degrees from horizontal, which is necessary for broad applicability of a liquid lithium PFC system.

  5. Boundary Condition in Liquid Thin Films Revealed through the Thermal Fluctuations of Their Free Surfaces.

    PubMed

    Pottier, B; Frétigny, C; Talini, L

    2015-06-01

    We investigate the properties of nanometric liquid films with a new noninvasive technique. We measure the spontaneous thermal fluctuations of the free surfaces of liquids to probe their hydrodynamic boundary condition at a solid wall. The surface fluctuations of a silicon oil film could be described with a no-slip boundary condition for film thicknesses down to 20 nm. Oppositely, a 4 nm negative slip length had to be introduced to describe the behavior of n-hexadecane, consistently with previous surface force apparatus data on the same system. Our results demonstrate that at vanishing flow a nanometric solidlike layer close to the wall may exist according to the nature of the liquid. PMID:26196646

  6. The threshold origin of solutocapillary Marangoni convection on a bounded free surface

    NASA Astrophysics Data System (ADS)

    Viviani, Antonio; Denisova, Maria; Kostarev, Konstantin; Zuev, Andrew

    2014-09-01

    The Marangoni convection is the key mechanism responsible for the motion of non-isothermal fluid with a free surface under microgravity conditions. It is generally assumed that the surface of a Newtonian fluid begins to move at any arbitrary small shear stress. However, the experiments show that under actual conditions the capillary fluid flow can be initiated by a certain (threshold) stress. For subthreshold shear stresses generated by the surface forces or volumetric flows, the fluid surface remains immovable. Such a behavior of the surface is caused by the existence of an adsorption layer formed by uncontrolled surface-active impurities contained in the fluid. The composition and amount of impurities absorbed on the surface are dependent on the degree of purification of the fluid and the value of its surface tension. The condition of a threshold initiation of the capillary motion has been determined experimentally for the case of development of the solutal Marangoni convection after placing a droplet of the surfactant liquor on the interface of water, aqueous surfactant solutions of lower concentrations and some organic fluids. A group of monohydric alcohols and carboxylic acids were used as the surfactants. It has been found that the value of the threshold difference in surfactant concentration rapidly increases with a decrease in fluid initial concentration and the characteristic dimension of the free surface. Due to the latter fact the threshold effects are of crucial importance for a variety of problems in microfluidics. It has been found that a threshold origin of a capillary motion is also peculiar to the liquid-liquid interface. The relationships between the threshold Marangoni number and the surface activity of a surfactant have been determined.

  7. Spherical Demons: Fast Diffeomorphic Landmark-Free Surface Registration

    PubMed Central

    Yeo, B.T. Thomas; Sabuncu, Mert R.; Vercauteren, Tom; Ayache, Nicholas; Fischl, Bruce; Golland, Polina

    2010-01-01

    We present the Spherical Demons algorithm for registering two spherical images. By exploiting spherical vector spline interpolation theory, we show that a large class of regularizors for the modified Demons objective function can be efficiently approximated on the sphere using iterative smoothing. Based on one parameter subgroups of diffeomorphisms, the resulting registration is diffeomorphic and fast. The Spherical Demons algorithm can also be modified to register a given spherical image to a probabilistic atlas. We demonstrate two variants of the algorithm corresponding to warping the atlas or warping the subject. Registration of a cortical surface mesh to an atlas mesh, both with more than 160k nodes requires less than 5 minutes when warping the atlas and less than 3 minutes when warping the subject on a Xeon 3.2GHz single processor machine. This is comparable to the fastest non-diffeomorphic landmark-free surface registration algorithms. Furthermore, the accuracy of our method compares favorably to the popular FreeSurfer registration algorithm. We validate the technique in two different applications that use registration to transfer segmentation labels onto a new image: (1) parcellation of in-vivo cortical surfaces and (2) Brodmann area localization in ex-vivo cortical surfaces. PMID:19709963

  8. Label-free surface plasmon sensing towards cancer diagnostics

    NASA Astrophysics Data System (ADS)

    Sankaranarayanan, Goutham

    The main objective of this thesis is to develop a conventional, home-built SPR bio-sensor to demonstrate bio-sensing applications. This emphasizes the understanding of basic concepts of Surface Plasmon Resonance and various interrogation techniques. Intensity Modulation was opted to perform the label-free SPR bio-sensing experiments due to its cost-efficient and compact setup. Later, label-free surface plasmon sensing was carried out to study and understand the bio-molecular interactions between (1). BSA and Anti BSA molecules and (2). Exosome/Liposome on thin metal (Au) films. Exosomes are cell-derived vesicles present in bodily fluids like blood, saliva, urine, epididymal fluid containing miRNAs, RNA, proteins, etc., at stable quantities during normal health conditions. The exosomes comprise varied constituents based on their cell origin from where they are secreted and is specific to that particular origin. However an exacerbated release is observed during tumor or cancer conditions. This increased level of exosomes present in the sample, can be detected using the SPR bio-sensor demonstrated in this thesis and effective thickness of adsorption on Au surface can be estimated. Also, chemically synthesized liposome particles were studied to determine if they can generate an equivalent sensor response to that of exosomes to consider them as an alternate. Finally a 10ppb Mercury (Hg) sensing was performed as part of Environment Monitoring application and results have been tabulated and compared.

  9. Fabrication of Adhesive Lenses Using Free Surface Shaping

    NASA Astrophysics Data System (ADS)

    Hoheisel, D.; Kelb, C.; Wall, M.; Roth, B.; Rissing, L.

    2013-09-01

    Two approaches for fabricating polymer lenses are presented in this paper. Both are based on filling circular holes with UV curing adhesives. Initially, the viscous adhesive material creates a liquid and spherical free surface due to its own surface tension. This shape is then preserved by curing with UV-hardening light. For the first approach, the holes are generated in a 4 inch Si-wafer by deep reactive ion etching (DRIE) and for the second, a polydimethylsiloxane (PDMS) mould is manufactured. Three types of UV-curing adhesives are investigated (NOA 61, NOA 88 and NEA 121 by Norland Products). Preliminary to the determination of the lens curvature, a contact angle goniometer is used for taking side view images of the lenses. The radius of curvature is then extracted via image processing with the software MATLAB®. Furthermore, the surface roughness of the PDMS mould and the generated lenses is measured with a white light interferometer to characterize the casting process. The resolution power of the generated lenses is evaluated by measurement of their point spread functions (psf) and modulation transfer functions (mtf), respectively.

  10. Glasses crystallize rapidly at free surfaces by growing crystals upward

    PubMed Central

    Sun, Ye; Zhu, Lei; Kearns, Kenneth L.; Ediger, Mark D.; Yu, Lian

    2011-01-01

    The crystallization of glasses and amorphous solids is studied in many fields to understand the stability of amorphous materials, the fabrication of glass ceramics, and the mechanism of biomineralization. Recent studies have found that crystal growth in organic glasses can be orders of magnitude faster at the free surface than in the interior, a phenomenon potentially important for understanding glass crystallization in general. Current explanations differ for surface-enhanced crystal growth, including released tension and enhanced mobility at glass surfaces. We report here a feature of the phenomenon relevant for elucidating its mechanism: Despite their higher densities, surface crystals rise substantially above the glass surface as they grow laterally, without penetrating deep into the bulk. For indomethacin (IMC), an organic glass able to grow surface crystals in two polymorphs (α and γ), the growth front can be hundreds of nanometers above the glass surface. The process of surface crystal growth, meanwhile, is unperturbed by eliminating bulk material deeper than some threshold depth (ca. 300 nm for α IMC and less than 180 nm for γ IMC). As a growth strategy, the upward-lateral growth of surface crystals increases the system’s surface energy, but can effectively take advantage of surface mobility and circumvent slow growth in the bulk. PMID:21444775

  11. Experimental and Numerical Investigation of Capillary Driven Free Surface Oscillations of Liquid Argon Under Non-Isothermal Conditions

    NASA Astrophysics Data System (ADS)

    Kulev, Nikolai; Dreyer, Michael E.

    Knowledge of dynamic behaviour of cryogenic fluids under microgravity is of key importance for the management of cryogenic propellants in space vehicles. In this work we present experimental and numerical investigations of the capillary driven free surface oscillations of liquid argon (Tsat = 87.3K @ 1013 hPa) under non-isothermal boundary conditions. Such oscillations take place during the reorientation of the equilibrium position of the free surface upon step reduction of gravity. The aim was to investigate the impact on the reorientation when the main capillary flow is superimposed in the vicinity of the contact line by a flow, induced by thermal effects due to heat flux from the vessel's hot wall towards the cold cryogenic liquid. The experiments were performed at the Bremen Drop Tower. Axial wall temperature gradients of averaged 0.15 K/mm -1.93 K/mm towards the free surface were implemented. A general dependence of the system behavior on the value of these gradients was observed. Thus the characteristics of the free surface oscillations vary accordingly. The aperiodic movement of the apparent contact line changes to a periodic one, accompanied by a distinctive change in the vapor pressure increase -hinting to a peak evaporation on the receding contact line. Nucleation boiling in the highest range of the axial wall temperature gradients, indicating the formation of thermal wall boundary layers, was also observed. The individual or combined action of the physical mechanisms of Marangoni convection, vapor recoil and evaporation/condensation are to be expected behind the observation. Numerical simulations of the drop tower experiments utilizing the VOF method were exploited in search for the explanation. Simulation results and comparison to the experiment are also presented.

  12. Influence of free surface curvature on the Pearson instability in Marangoni convection

    NASA Astrophysics Data System (ADS)

    Hu, W. R.

    The Peason instability in a liquid layer bounded by a plate solid boundary with higher constant temperature and a plane free surface with lower constant temperatures in the microgravity environment has by extensively studied The free surface in the microgravity environment tends to be curved in general as a spherical shape and the plane configuration of free surface is a special case In the present paper a system of liquid layer bounded by a plat solid boundary with higher constant temperature and a curved free surface with lower non-uniform temperature is studied The temperature gradient on the free surface will induce the thermocapillary convection and the onset of Marangoni convection is coupled with the thermocapillary convection The thermocapillary convection induced by the temperature gradient on the curved free surface and its influence on the Marangoni convection are studied in the present paper

  13. Slow viscous gravity-driven interaction between a bubble and a free surface with unequal surface tensions

    NASA Astrophysics Data System (ADS)

    Guémas, Marine; Sellier, Antoine; Pigeonneau, Franck

    2015-04-01

    The axisymmetric gravity-driven dynamics of a bubble rising toward a free surface is addressed for gas-liquid interfaces having unequal surface tensions. The liquid flow is governed by the Stokes equations which are here solved using a boundary element method in axisymmetric configuration. Within this framework, two dimensionless numbers arise: the Bond number Bo1 based on the surface tension of the bubble interface and the surface tension ratio γ ˆ comparing the free surface and bubble surface tensions. Under a careful and discussed selection of the code key settings (number of boundary elements, initial bubble location, and distance beyond which the free surface is truncated), it has been possible to numerically and accurately track in time the bubble and free surface shapes for several values of ( Bo 1 , γ ˆ ) . The long-time shapes are found to deeply depend upon both Bo1 and γ ˆ and also to compare well with the shapes predicted in Princen and Mason ["Shape of a fluid drop at a fluid-liquid interface. II. Theory for three-phase systems," J. Colloid. Sci. 20, 246-266 (1965)] using a hydrostatic model in which both surfaces are touching. Similarly, the drainage dynamics of the liquid film thickness between the bubble and the free surface depends on ( Bo 1 , γ ˆ ) . The long-time film thickness exponentially decays in time and a so-called thinning rate α for which the numerical behaviors and a simple model reveal two basic behaviors: (i) at small Bond number, α behaves as 1/Bo1 and (ii) at large Bond number, α is nearly constant. In addition, it is found that in the entire range of the quantity χ = ( 1 + γ ˆ ) Bo 1 / ( 2 γ ˆ ) , the thinning rate α is well approximated by the function 1/(18χ) + α∞ with α∞ ≈ 0.158. Such a result also permits one to estimate the typical drainage time versus the initial bubble radius a, the liquid density ρ and viscosity μ, the gravity and the free surface, and bubble surface tensions.

  14. Predictions of nearshore hydrodynamics based on free-surface lattice Boltzmann approximations

    NASA Astrophysics Data System (ADS)

    Frandsen, J. B.; Mier-Torrecilla, M.; Zurita-Gotor, M.; Holman, D. M.

    2012-04-01

    The focus of the present free-surface model developments is to utilize gas dynamics theory to predict and investigate underlying mechanisms of the dynamics of nonlinear water waves. Since water wave mechanics is a topic not concerned with the notions from thermodynamics, the basics of the physics of incompressible gas dynamics provides a relatively simple means for describing the theory and predictions of nonlinear wave propagation through advanced random and nonlinear particle collision processes [1]. Nonlinear free-surface physics are investigated using the Lattice Boltzmann Method (LBM) at intermediate to shallow water depth. The LBM simulates fluid flow by tracking particle distributions in a Lagrangian manner. The particles are constrained to move on regular or octree lattices depending on wave steepness and/or wave-structure interaction details sought. The Boltzmann equation relates the time evolution and spatial variation of a collection of molecules to a collision operator that describes the interaction of the molecules. Mathematically, the collision integral of the LB equation poses difficulties when solution of the equation is sought. Investigators overcome this through descriptions of models with different levels of accuracy in the approximations of the integral. We consider a model in which the collision assumption is approximated by a multiple relaxation time form. The free-surface algorithm involves an interface tracking scheme based on the volume fraction of the fluid combined with the LBM for the advection equation in which the solver reconstructs the missing probability distribution functions taking into account the distance to the interface [2, 3]. The approximate forms of the LBM describe comparisons of the nonlinear shallow water equations and the Navier Stokes equations. Test cases involving predictions of run-up/run-down on cylinders and beaches are shown. The wet-dry interface conditions, viscosity treatment, surface break-up amongst others

  15. Subduction Initiation from a Stagnant Lid: New Insights from Numerical Models with a Free Surface

    NASA Astrophysics Data System (ADS)

    Crameri, Fabio; Tackley, Paul

    2016-04-01

    Subduction initiation is key in understanding the dynamic evolution of the Earth and its fundamental difference to all other rocky planetary bodies in our solar system. Despite recent progress, the question about how a stiff, mostly stagnant planetary lid can break and become part in the global overturn of the mantle is still unresolved. Here, we present results on subduction initiation obtained by dynamically self-consistent, time-dependent numerical modelling of mantle convection and single-sided subduction (Crameri et al., 2012b) using the finite-difference, multigrid code StagYY (Tackley 2008). We show that the stress distribution and resulting deformation of the lithosphere is strongly controlled by the top boundary formulation: A free surface enables surface topography and plate bending, increases gravitational sliding of the plates and leads to more realistic, lithosphere-scale shear zones. As a consequence, subduction initiation induced by regional mantle flow is significantly favoured by a free surface compared to the commonly-applied, vertically-fixed (i.e., free-slip) surface. In addition, we present global, three-dimensional mantle convection experiments (see e.g. Crameri and Tackley, 2014) that employ basal heating that leads to narrow mantle plumes. Narrow mantle plumes impinging on the base of the plate cause locally weak plate segments and a large topography at the lithosphere-asthenosphere boundary. Both are shown to be key to induce subduction initiation. Finally, our model self-consistently reproduces an episodic lid with a fast global overturn due to the hotter mantle developed below a former stagnant lid. We conclude that once in a stagnant-lid mode, a planet (like Venus) thus preferentially evolves by temporally discrete, global overturn events rather than by a continuous recycling of lid. REFERENCES Crameri, F, Tackley, P.J, Meilick, I, Gerya, T.V, Kaus, B.J.P (2012) A free plate surface and weak oceanic crust produce single-sided subduction

  16. A new free-surface stabilization algorithm for geodynamical modelling: Theory and numerical tests

    NASA Astrophysics Data System (ADS)

    Andrés-Martínez, Miguel; Morgan, Jason P.; Pérez-Gussinyé, Marta; Rüpke, Lars

    2015-09-01

    The surface of the solid Earth is effectively stress free in its subaerial portions, and hydrostatic beneath the oceans. Unfortunately, this type of boundary condition is difficult to treat computationally, and for computational convenience, numerical models have often used simpler approximations that do not involve a normal stress-loaded, shear-stress free top surface that is free to move. Viscous flow models with a computational free surface typically confront stability problems when the time step is bigger than the viscous relaxation time. The small time step required for stability (< 2 Kyr) makes this type of model computationally intensive, so there remains a need to develop strategies that mitigate the stability problem by making larger (at least ∼10 Kyr) time steps stable and accurate. Here we present a new free-surface stabilization algorithm for finite element codes which solves the stability problem by adding to the Stokes formulation an intrinsic penalization term equivalent to a portion of the future load at the surface nodes. Our algorithm is straightforward to implement and can be used with both Eulerian or Lagrangian grids. It includes α and β parameters to respectively control both the vertical and the horizontal slope-dependent penalization terms, and uses Uzawa-like iterations to solve the resulting system at a cost comparable to a non-stress free surface formulation. Four tests were carried out in order to study the accuracy and the stability of the algorithm: (1) a decaying first-order sinusoidal topography test, (2) a decaying high-order sinusoidal topography test, (3) a Rayleigh-Taylor instability test, and (4) a steep-slope test. For these tests, we investigate which α and β parameters give the best results in terms of both accuracy and stability. We also compare the accuracy and the stability of our algorithm with a similar implicit approach recently developed by Kaus et al. (2010). We find that our algorithm is slightly more accurate

  17. High spatio-temporal resolution PIV of laminar boundary layer relaxation instability at the free surface of a jet

    NASA Astrophysics Data System (ADS)

    Andre, Matthieu; Bardet, Philippe

    2012-11-01

    In high-speed free surface flows, microscale instabilities can lead to dramatic macroscale effects such as waves, breakup, or air entrainment. The importance of jets in practical applications requires a better understanding of the mechanisms leading to these instabilities. This experimental study focuses on laminar boundary layer relaxation (LBLR) instability. This has received fewer attention than other instabilities due to the small scale, the high Reynolds number and the proximity of an interface. The experiment features a 20 . 3 mm × 146 . 0 mm laminar slab wall jet exiting a nozzle into quiescent air (Re= 3 . 1 ×104 to 1 . 6 ×105). The free surface is flat near the nozzle exit then the LBLR leads to 2D capillary waves which can become very steep eventually resulting in primary breakup and air entrainment. The inception and growth of the capillaries are investigated using time-resolved PIV coupled with PLIF to track the free surface. A magnification of 4 allows a spatial and temporal resolution better than 0.1mm and 0.1ms, respectively. These high resolution results show the role of vortices -created by the roll-up of the shear layer below the surface- in the formation of capillaries. Vortices and waves are a coupled system; the waves can sustain, damp, or amplify. This study has been supported by the start-up funds from The George Washington University to Dr. Bardet.

  18. Nonlinear simulation of free surfaces and atomization in pressure swirl atomizers

    NASA Astrophysics Data System (ADS)

    Park, Hongbok; Heister, Stephen D.

    2006-05-01

    A fully nonlinear boundary element method (BEM) model has been developed to simulate the pressure swirl or simplex atomizer. The free surface inside the vortex chamber and within the hollow-cone/primary atomization zone is simulated with a fourth order scheme thereby permitting investigation of highly distorted surfaces up to the point where atomization occurs. For the axisymmetric calculations, annular rings of fluid are pinched from the main liquid domain. Swirling flow is simulated via a superposition of a potential vortex with the base axial flow emanating from the nozzle in a BEM formulation. Results show good comparison to film thicknesses from test data as well as from linear one-dimensional theory. Parametric studies are conducted to assess the influence of injector geometry and flow characteristics on film thickness and spray angle produced by the atomizer. Limited results are also provided to compare droplet sizes with experimental data. In this regard, the linear stability analysis of Ponstein is used to predict the number of droplets created from each ring of fluid shed by the axisymmetric calculation.

  19. Orbital Oscillations of a Cylinder in Presence of a Free-Surface: Vortex Formation and Loading

    NASA Astrophysics Data System (ADS)

    Cetiner, O.; Zhu, Q.; Lin, J.-C.; Unal, M. F.; Rockwell, D.

    1996-11-01

    A cylinder is subject to circular orbital motion, as part of a study involving g eneralized Lissajous trajectories of bodies, in order to determine the force-vorticity rela tionships. Space-time vorticity fields, via high-image-density PIV, are acquired simultaneo usly with lift and drag. Both impulsively-started and steady-state orbital motions ar e addressed, in order to determine, at a given phase of the oscillation cycle, the history effects of previously generated vorticity. During the orbital trajectory of the cylinder, the near wake exhibits a global rotation relative to the cylinder, as vortices are f ormed. This vortex formation appears to be highly sensitive to history effects and to b ias induced by small values of steady flow. When the extreme position of the cylinde r during the orbital motion is of the order of one diameter from the free-surface, the pattern of vortex formation is substantially altered. The lift and drag signatur es exhibit corresponding changes. These features of the loading are interpreted using theor etical concepts, including evaluation of moments of vorticity about the cylinder. Reyno lds number effects on the shedding process are currently being addressed in the cont ext of observations for unidirectional, oscillatory flow and steady flow.

  20. Thermal characteristics of air flow cooling in the lithium ion batteries experimental chamber

    SciTech Connect

    Lukhanin A.; Rohatgi U.; Belyaev, A.; Fedorchenko, D.; Khazhmuradov, M.; Lukhanin, O; Rudychev, I.

    2012-07-08

    A battery pack prototype has been designed and built to evaluate various air cooling concepts for the thermal management of Li-ion batteries. The heat generation from the Li-Ion batteries was simulated with electrical heat generation devices with the same dimensions as the Li-Ion battery (200 mm x 150 mm x 12 mm). Each battery simulator generates up to 15W of heat. There are 20 temperature probes placed uniformly on the surface of the battery simulator, which can measure temperatures in the range from -40 C to +120 C. The prototype for the pack has up to 100 battery simulators and temperature probes are recorder using a PC based DAQ system. We can measure the average surface temperature of the simulator, temperature distribution on each surface and temperature distributions in the pack. The pack which holds the battery simulators is built as a crate, with adjustable gap (varies from 2mm to 5mm) between the simulators for air flow channel studies. The total system flow rate and the inlet flow temperature are controlled during the test. The cooling channel with various heat transfer enhancing devices can be installed between the simulators to investigate the cooling performance. The prototype was designed to configure the number of cooling channels from one to hundred Li-ion battery simulators. The pack is thermally isolated which prevents heat transfer from the pack to the surroundings. The flow device can provide the air flow rate in the gap of up to 5m/s velocity and air temperature in the range from -30 C to +50 C. Test results are compared with computational modeling of the test configurations. The present test set up will be used for future tests for developing and validating new cooling concepts such as surface conditions or heat pipes.

  1. Topologies of velocity-field stagnation points generated by a single pair of magnets in free-surface electromagnetic experiments.

    PubMed

    de la Cruz, J M García; Vassilicos, J C; Rossi, L

    2014-10-01

    The velocity fields generated by a static pair of magnets in free-surface electromagnetically forced flows are analyzed for different magnet attitudes, ionic currents, and brine depths. A wide range of laminar velocity fields is obtained despite the forcing simplicity. The velocity fields are classified according to their temporal mean flow topology, which strongly depends on the forcing geometry but barely on its strength, even through the bifurcation to unsteady regimes. The mean flow topology possesses a major influence on the critical Reynolds number Rec under which the steady velocity fields remain stable. The qualitative comparison of the dependence of Rec on the topology is in agreement with previous works. The unsteady configurations evidence the advection of smaller flow structures by the largest scales, commonly known as "sweeping." PMID:25375588

  2. RTM-based Teleseismic Reflection Tomography with Free Surface Multiples

    NASA Astrophysics Data System (ADS)

    Burdick, S. A.; De Hoop, M. V.; van der Hilst, R. D.

    2013-12-01

    Receiver function analysis of teleseismic converted and free surface reflected phases has long been a cornerstone of lithospheric studies. Discontinuities in elastic properties are revealed by deconvolving the incident wavefield from scattered phases and projecting the time differences to depth to form an image. The accuracy of the image is determined to a large extent by the accuracy of the method and background velocity model used, but popular approaches for projecting receiver functions to depth commonly rely on simplifying assumptions of a 1D velocity and planar discontinuities. In tectonically complex regions like subduction zones and rift systems, strong heterogeneity can create an ambiguous tradeoff between the background velocity and the depth of the discontinuities. Furthermore, such structures are apt to create caustics at high frequencies, rendering ray-based methods inadequate. In order to better constrain the background velocity and correctly place the discontinuities at depth, we employ a novel reverse-time migration (RTM) based reflection tomography method. We adapt our reflection tomography from exploration seismology for use with teleseismic phases. Active source methods for exploration have focused on the annihilation of extended images - image gathers formed with different subsurface angle or offset information - as a means of judging the accuracy of the model. Applying these approaches to teleseismic data is untenable because 1) the sparse and uneven distribution of earthquake sources leads to the incomplete construction of extended image, 2) the imperfect separation and source deconvolution of the scattered wavefield render previous error measurements unreliable, and 3) the planar geometry of incoming arrivals makes measures of subsurface offset insensitive to perturbations in the model. To overcome these obstacles, we have developed a flexible approach based on pairwise single-source image correlations. We determine the success of the RTM and

  3. Free-surface stability criterion as affected by velocity distribution

    USGS Publications Warehouse

    Cheng-Lung, Chen

    1995-01-01

    This paper examines how the velocity distribution of flow in open channels affects the kinematic and dynamic wave velocities, from which the various forms of the Vedernikov number V can be formulated. When V >1, disturbances created in open-channel flow will amplify in the form of roll waves; when V <1, some (though not all) disturbances will attenuate. A study of the Vedernikov stability criterion reveals that it can be readily deduced within the framework of the kinematic and dynamic wave theories by comparing the kinematic wave velocity to the corresponding dynamic wave velocity. -from Author

  4. Lithium-sulfur hexafluoride magnetohydrodynamic power system

    SciTech Connect

    Dobran, F.

    1987-02-24

    A method is described to operate a two-phase flow magnetohydrodynamic electric power generation system with liquid lithium and gaseous sulfur-hexafluoride flowing through a diverging channel, with side electrodes to remove the electric current generated in the flowing liquid lithium, across the applied magnetic field that is perpendicular to both the flow velocity and electrodes. Sulfur-hexafluoride is dispersed in the form of small bubbles and reacts with liquid lithium that forms a continuous phase to conduct the current between the electrodes so as to produce a near isothermal two-phase flow mixture and provides for an expansion of lithium across the magnetic field in the generator.

  5. Free surface modeling in OWC chamber with parabolic side walls using 3D BEM

    SciTech Connect

    Hasanabad, Madjid Ghodsi

    2015-03-10

    In this paper, BEM was used for free surface modeling in OWC chamber and out of it. Linear kinematic and dynamic boundary conditions were used for free surface out of OWC chamber and nonlinear forms were used for free surface in the chamber. These boundary conditions were discretized by finite differences method. Also, some thermodynamics relations were applied for trapped air behavior modeling in OWC chamber. Wave specifications in Chabahar region were used in modeling because these waves have an acceptable power for electricity generation. The results show a good agreement with results of other researches.

  6. Micro-swimmer dynamics in free-surface turbulence subject to wind stress

    NASA Astrophysics Data System (ADS)

    Marchioli, Cristian; Lovecchio, Salvatore; Soldati, Alfredo

    2015-11-01

    We examine the effect of wind-induced shear on the orientation and distribution of motile micro-swimmers in free-surface turbulence. Winds blowing above the air-water interface can influence the distribution and productivity of motile organisms via the shear generated just below the surface. Swimmer dynamics depend not only by the advection of the fluid but also by external stimuli like nutrient concentration, light, gravity. Here we focus on gyrotaxis, resulting from the gravitational torque generated by an asymmetric mass distribution within the organism. The combination of such torque with the viscous torque due to shear can reorient swimmers, reducing their vertical migration and causing entrapment in horizontal fluid layers. Through DNS-based Euler-Lagrangian simulations we investigate the effect of wind-induced shear on the motion of gyrotactic swimmers in turbulent open channel flow. We consider different wind directions and swimmers with different reorientation time (reflecting the ability to react to turbulent fluctuations). We show that only stable (high-gyrotaxis) swimmers may reach the surface and form densely concentrated filaments, the topology of which depends on the wind direction. Otherwise swimmers exhibit weaker vertical fluxes and segregation at the surface.

  7. A free surface capturing discretization for the staggered grid finite difference scheme

    NASA Astrophysics Data System (ADS)

    Duretz, T.; May, D. A.; Yamato, P.

    2016-03-01

    The coupling that exists between surface processes and deformation within both the shallow crust and the deeper mantle-lithosphere has stimulated the development of computational geodynamic models that incorporate a free surface boundary condition. We introduce a treatment of this boundary condition that is suitable for staggered grid, finite difference schemes employing a structured Eulerian mesh. Our interface capturing treatment discretizes the free surface boundary condition via an interface that conforms with the edges of control volumes (e.g. a `staircase' representation) and requires only local stencil modifications to be performed. Comparisons with analytic solutions verify that the method is first-order accurate. Additional intermodel comparisons are performed between known reference models to further validate our free surface approximation. Lastly, we demonstrate the applicability of a multigrid solver to our free surface methodology and demonstrate that the local stencil modifications do not strongly influence the convergence of the iterative solver.

  8. Statistics of particle concentration in free-surface turbulence

    SciTech Connect

    Bandi, Mahesh M; Larkin, J; Goldburg, W

    2009-01-01

    Particles on the surface of an incompressible fluid maintained in a turbulent steady-state cluster into spatio-temporally complex flow structures. We experimentally study the statistics of particle concentration n(r, t) over various coarse-grained scales r' in the inertial range. Another control parameter is the Taylor Microscale Reynolds number Re{sub {lambda}}. The focus is on the steady state probability density function {Pi}(n{sub r}). Attention is also given to the variance {sigma}{sup 2}(r, t) of this PDF, since it yields information about the topology of the coagulated structures. Where possible, the results are compared and contrasted with those obtained in a recent analytical and numerical study of two-dimensional synthetic turbulence by Ducasse and Pumir. There, but not here, the dimensionless compressibility C is an important control parameter.

  9. Bouncing jet: a Newtonian liquid rebounding off a free surface.

    PubMed

    Thrasher, Matthew; Jung, Sunghwan; Pang, Yee Kwong; Chuu, Chih-Piao; Swinney, Harry L

    2007-11-01

    We find that a liquid jet can bounce off a bath of the same liquid if the bath is moving horizontally with respect to the jet. Previous observations of jets rebounding off a bath (e.g., the Kaye effect) have been reported only for non-Newtonian fluids, while we observe bouncing jets in a variety of Newtonian fluids, including mineral oil poured by hand. A thin layer of air separates the bouncing jet from the bath, and the relative motion replenishes the film of air. Jets with one or two bounces are stable for a range of viscosity, jet flow rate and velocity, and bath velocity. The bouncing phenomenon exhibits hysteresis and multiple steady states. PMID:18233768

  10. Bouncing jet: A Newtonian liquid rebounding off a free surface

    NASA Astrophysics Data System (ADS)

    Thrasher, Matthew; Jung, Sunghwan; Pang, Yee Kwong; Chuu, Chih-Piao; Swinney, Harry L.

    2007-11-01

    We find that a liquid jet can bounce off a bath of the same liquid if the bath is moving horizontally with respect to the jet. Previous observations of jets rebounding off a bath (e.g., the Kaye effect) have been reported only for non-Newtonian fluids, while we observe bouncing jets in a variety of Newtonian fluids, including mineral oil poured by hand. A thin layer of air separates the bouncing jet from the bath, and the relative motion replenishes the film of air. Jets with one or two bounces are stable for a range of viscosity, jet flow rate and velocity, and bath velocity. The bouncing phenomenon exhibits hysteresis and multiple steady states.

  11. Finite difference elastic wave modeling with an irregular free surface using ADER scheme

    NASA Astrophysics Data System (ADS)

    Almuhaidib, Abdulaziz M.; Nafi Toksöz, M.

    2015-06-01

    In numerical modeling of seismic wave propagation in the earth, we encounter two important issues: the free surface and the topography of the surface (i.e. irregularities). In this study, we develop a 2D finite difference solver for the elastic wave equation that combines a 4th- order ADER scheme (Arbitrary high-order accuracy using DERivatives), which is widely used in aeroacoustics, with the characteristic variable method at the free surface boundary. The idea is to treat the free surface boundary explicitly by using ghost values of the solution for points beyond the free surface to impose the physical boundary condition. The method is based on the velocity-stress formulation. The ultimate goal is to develop a numerical solver for the elastic wave equation that is stable, accurate and computationally efficient. The solver treats smooth arbitrary-shaped boundaries as simple plane boundaries. The computational cost added by treating the topography is negligible compared to flat free surface because only a small number of grid points near the boundary need to be computed. In the presence of topography, using 10 grid points per shortest shear-wavelength, the solver yields accurate results. Benchmark numerical tests using several complex models that are solved by our method and other independent accurate methods show an excellent agreement, confirming the validity of the method for modeling elastic waves with an irregular free surface.

  12. Interaction of two spark-generated bubbles near a confined free surface

    NASA Astrophysics Data System (ADS)

    Saleki-Haselghoubi, Noureyeh; Shervani-Tabar, Mohammad Taghi; Taeibi-Rahni, Mohammad; Dadvand, Abdolrahman

    2016-06-01

    In this paper, the oscillation of two spark-generated bubbles placed on a vertical column in close proximity to a confined free surface is considered. The confined free surface is accorded by the top opening of different configurations. These configurations include (i) a centrally perforated horizontal flat plate ({θ=90°)}, (ii) vertically placed cylinder ({θ=0°)} and (iii) nozzle ({θ >0°)}. The main objective of the present work is to study the effects of key parameters such as the nozzle geometry, the locations of the energy input (i.e., initial position of the bubbles with respect to each other and relative to the free surface) on the dynamics of the two bubbles and the free surface. It was found that the lifetime of the upper bubble decreases from the vertical cylinder to the flat plate case. In addition, by reducing the inter-bubble distance, the lifetime of the upper bubble becomes longer and the repulsion between two bubbles during the expansion phase is stronger. Finally, by reducing the upper bubble-free surface distance, the repulsion between two bubbles during expansion phase increases, the tendency of the upper bubble to rebound and initiate another oscillation cycle decreases, and the amplitude of elevation of the free surface increases.

  13. Large-eddy simulation of coupled turbulence, free surface, and sand wave evolution in an open channel

    NASA Astrophysics Data System (ADS)

    Khosronejad, A.; Sotiropoulos, F.

    2013-12-01

    We develop and validate a coupled 3D numerical model for carrying out three-phase large-eddy simulations of turbulence, free-surface, and sand waves-bed morphodynamics under live bed conditions. We employ the Fluid-Structure Interaction Curvilinear Immersed Boundary (FSI-CURVIB) method of Khosronejad et al. (Adv. in Water Res., 2011). The LES is implemented in the context of the CURVIB method using wall modeling (Kang and Sotiropoulos, Adv. in Water Res., 2011). Free-surface motion is simulated by coupling the CURVIB method with a two-phase level set approach as in Kang and Sotiropoulos (Adv. in Water Res., 2012). The mobile channel bed is discretized with an unstructured triangular grid and treated as the sharp-interface immersed boundary embedded in a background curvilinear mesh. Transport of bed load and suspended load sediments are combined in the non-equilibrium form of the Exner-Poyla for the bed surface elevation, which evolves due to the spatio-temporally varying bed shear stress field induced by the turbulent flow. Simulations are carried out for the rectangular flume experiments of Venditti et al. (2005). It is shown that the model can accurately capture sand-wave initiation, growth, and migration processes observed in the experiment. The simulated bed-forms are found to have amplitude and wave length scales of ~5 cm and ~30 cm, respectively. The effects of free-surface on bed-form dynamics is also quantified by comparing the three-phase simulation results with two-phase simulations using a fixed rigid-lid as the water surface.

  14. Thermo-mechanically coupled subduction using AMR together with a true free surface and sticky air in ASPECT

    NASA Astrophysics Data System (ADS)

    Fraters, Menno; Glerum, Anne; Thieulot, Cedric; Spakman, Wim

    2015-04-01

    ASPECT (Kronbichler et al., 2012), short for Advanced Solver for Problems in Earth's ConvecTion, is a new Finite Element code which was originally designed for thermally driven (mantle) convection and is built on state of the art numerical methods (adaptive mesh refinement, linear and non-linear solver, stabilization of transport dominated processes and a high scalability on multiple processors). Here we present an application of ASPECT to the modelling of fully thermo-mechanically coupled subduction. Our model contains in the case of a true free surface three different compositions: two different crustal compositions, one on top of the subducting plate and one on top of the overriding plate, and a mantle composition. In the case of a free surface through a sticky air layer, a fourth composition representing this sticky air is added. We implemented a viscoplastic rheology using frictional plasticity and a composite viscosity defined by diffusion and dislocation creep. The lithospheric part of the mantle has the same composition as the rest of the mantle but has a higher viscosity because of a lower temperature. The temperature field is implemented in ASPECT as follows: a linear temperature gradient for the lithosphere and an adiabatic geotherm for the sublithospheric mantle. The Initial slab temperature is defined using the analytical solution of McKenzie (1970). The plates can be pushed from the sides of the model, and correspondingly it is possible to define an additional independent mantle in/out flow through the boundaries. We will show a preliminary set of models, highlighting the current codes capabilities, such as the fine tuned use of Adaptive Mesh Refinement in combination with topography development both through a true free surface and sticky air and solving for strongly non-linear rheologies.

  15. Thermo-mechanically coupled subduction with a free surface using ASPECT

    NASA Astrophysics Data System (ADS)

    Fraters, Menno; Glerum, Anne; Thieulot, Cedric; Spakman, Wim

    2014-05-01

    ASPECT (Kronbichler et al., 2012), short for Advanced Solver for Problems in Earth's ConvecTion, is a new Finite Element code which was originally designed for thermally driven (mantle) convection and is built on state of the art numerical methods (adaptive mesh refinement, linear and nonlinear solver, stabilization of transport dominated processes and a high scalability on multiple processors). Here we present an application of ASPECT to modeling of fully thermo-mechanically coupled subduction. Our subduction model contains three different compositions: a crustal composition on top of both the subducting slab and the overriding plate, a mantle composition and a sticky air composition, which allows for simulating a free surface for modeling topography build-up. We implemented a visco-plastic rheology using frictional plasticity and a composite viscosity defined by diffusion and dislocation creep. The lithospheric mantle has the same composition as the mantle but has a higher viscosity because of a lower temperature. The temperature field is implemented in ASPECT as follows: a linear temperature gradient for the lithosphere and an adiabatic geotherm for the sublithospheric mantle. Initial slab temperature is defined using the analytical solution of McKenzie (1970). The plates can be pushed from the sides of the model, and it is possible to define an additional independent mantle in/out flow through the boundaries. We will show a preliminary set of models, highlighting the codes capabilities, such as the Adaptive Mesh Refinement, topography development and the influence of mantle flow on the subduction evolution. Kronbichler, M., Heister, T., and Bangerth, W. (2012), High accuracy mantle convection simulation through modern numerical methods, Geophysical Journal International,191, 12-29, doi:10.1111/j.1365-246X.2012.05609. McKenzie, D.P. (1970), Temperature and potential temperature beneath island arcs, Teconophysics, 10, 357-366, doi:10.1016/0040-1951(70)90115-0.

  16. Method and apparatus to produce and maintain a thick, flowing, liquid lithium first wall for toroidal magnetic confinement DT fusion reactors

    DOEpatents

    Woolley, Robert D.

    2002-01-01

    A system for forming a thick flowing liquid metal, in this case lithium, layer on the inside wall of a toroid containing the plasma of a deuterium-tritium fusion reactor. The presence of the liquid metal layer or first wall serves to prevent neutron damage to the walls of the toroid. A poloidal current in the liquid metal layer is oriented so that it flows in the same direction as the current in a series of external magnets used to confine the plasma. This current alignment results in the liquid metal being forced against the wall of the toroid. After the liquid metal exits the toroid it is pumped to a heat extraction and power conversion device prior to being reentering the toroid.

  17. On the Finite-Time Splash and Splat Singularities for the 3-D Free-Surface Euler Equations

    NASA Astrophysics Data System (ADS)

    Coutand, Daniel; Shkoller, Steve

    2014-01-01

    We prove that the 3-D free-surface incompressible Euler equations with regular initial geometries and velocity fields have solutions which can form a finite-time "splash" (or "splat") singularity first introduced in Castro et al. (Splash singularity for water waves, http://arxiv.org/abs/1106.2120v2, 2011), wherein the evolving 2-D hypersurface, the moving boundary of the fluid domain, self-intersects at a point (or on surface). Such singularities can occur when the crest of a breaking wave falls unto its trough, or in the study of drop impact upon liquid surfaces. Our approach is founded upon the Lagrangian description of the free-boundary problem, combined with a novel approximation scheme of a finite collection of local coordinate charts; as such we are able to analyze a rather general set of geometries for the evolving 2-D free-surface of the fluid. We do not assume the fluid is irrotational, and as such, our method can be used for a number of other fluid interface problems, including compressible flows, plasmas, as well as the inclusion of surface tension effects.

  18. Free-Surface Roughness Correlations with the Near-Surface Turbulence

    NASA Astrophysics Data System (ADS)

    Dabiri, Dana; Gharib, Morteza

    1999-11-01

    Free-Surface Roughness Correlations with the Near-Surface Turbulence Dana Dabiri & Morteza Gharib CALTECH Understanding the correlation of the free-surface roughness with the near-surface turbulence can provide correct and proper models for LES and RANS codes. Measurements of both the near surface turbulence, and the free surface deformation are obtained simultaneously. The near surface turbulence is measured using DPIV, and the free surface roughness is measured using a two-dimensional gradient detector. These measurements were done looking at a shear layer interacting with a free surface. The Reynold's number and Froude number are 7000, and 0.07, respectively. Statistical calculations provide interesting u'v', h'v', h'u', h'u'v', and h'w' results. Spanwise Reynold's stress (u'v') plots show a gaussian behavior, while its centerline value is roughly constant with y. h'u' is symmetric with respect to the shear layer's centerline, showing a negative correlation on the high speed side and a positive correlation on the low speed side. Correlation of h' with the vorticity fluctuation, w', shows a skewed gaussian spanwise behavior. Lastly, the roughness spectrum shows a -11/3 spectra, as shown by George et al. (JFM, 1984). *Sponsored by ONR (N00014-98-1-0017)

  19. Improved free-surface expression for frequency-domain elastic optimal mixed-grid modeling

    NASA Astrophysics Data System (ADS)

    Cao, Jian; Chen, Jing-Bo; Dai, Meng-Xue

    2016-07-01

    An accurate and efficient forward modeling is the foundation of full-waveform inversion (FWI). In elastic wave modeling, one of the key problems is how to deal with the free-surface boundary condition appropriately. For the representation of the free-surface boundary condition, conventional displacement-based approaches and staggered-grid approaches are often used in time-domain. In frequency-domain, considering the saving of storage and CPU time, we integrate the idea of physical parameter-modified staggered-grid approach in time-domain with an elastic optimal mixed-grid modeling scheme to design an improved parameter-modified free-surface expression. Accuracy analysis shows that an elastic optimal mixed-grid modeling scheme using the parameter-modified free-surface expression can provide more accurate solutions with only 4 grid points per smallest shear wavelength than conventional displacement-based approaches and is stable for most Poisson ratios. Besides, it also yields smaller condition number of the resulting impedance matrix than conventional displacement-based approaches in laterally varying complex media. These advantages reveal great potential of this free-surface expression in big-data practical application.

  20. Stresses due to Squeeze Flow between Particles Surrounded by an Electrolyte Solution with Application to Lithium-Ion Batteries

    NASA Astrophysics Data System (ADS)

    Conlisk, A. T.; Zhang, Cong

    2013-11-01

    Large stresses are induced during lithium-ion battery charging and discharging, termed intercalation and deintercalation stresses. Current models of the stresses in lithium-ion batteries in the literature seldom consider the influence of the interaction between the particles within the electrodes on the stress distribution. The particles within lithium-ion battery electrodes can undergo relative motion with relative velocities of different magnitudes and directions. One important mode of motion manifests itself as two particles approaching each other. The interaction is mediated by the electrolyte between the particles. The relative motion of the particles induces significant pressures and the primary objective of this work is to propose a source of mechanical stresses as a consequence of the dynamic squeezing motion as opposed to a static environment considered in the battery literature. Other applications in the biomedical field are also discussed. Supported by DOE Graduate Automotive Technology Education (GATE), OSU Center for Automotive Research and OSU NSEC Center for the Affordable Nanoengineering of Polymeric Biomedical Devices.

  1. Nucleation of cracks near the free surface in deformed metallic nanomaterials with a bimodal structure

    NASA Astrophysics Data System (ADS)

    Ovid'ko, I. A.; Sheinerman, A. G.

    2016-06-01

    A theoretical model that effectively describes the nucleation of cracks in stress fields of dislocation pile-ups near the free surface in metallic nanomaterials with a bimodal structure has been developed. The dependences of the critical shear stress τ c (for the formation of a crack with an equilibrium length of 10 nm on a dislocation pile-up near the surface) on the size d of a grain containing the dislocation pile-up have been calculated for copper with a bimodal structure. Theoretically, it has been found that the critical shear stress τ c for the nucleation of a crack near the free surface in a nanomaterial with a bimodal structure is approximately 30% higher than that for the crack nucleation within the nanomaterial at a distance from the free surface.

  2. Envelope Synthesis on the Free Surface of a Random Elastic Medium Based on the Markov Approximation

    NASA Astrophysics Data System (ADS)

    Emoto, K.; Sato, H.; Nishimura, T.

    2008-12-01

    Short-period seismograms mostly consist of the waves scattered by random inhomogeneities of the solid earth. For P-waves, the apparent duration is broadened and the transverse amplitude is excited with travel distance increasing. Usually, we observe the seismic waves on the free surface. For the homogeneous medium case, the vertical incident P-wave amplitude is doubled at the free surface; however, for the inhomogeneous medium case it has not been clear how the free surface affects wave amplitudes since the ray directions are widely distributed because of scattering. Here, we develop the synthesis of vector-wave envelopes on the free surface of a random medium. When the wave length is shorter than the correlation distance of 3-D infinite random media, characterized by a Gaussian autocorrelation function, Sato (2006) derives analytical solutions of vector-wave envelopes on the basis of the Markov approximation, which is a stochastic extension of the split stem method to solve the parabolic wave equation. We extend his method for the synthesis of vector-wave envelopes on the free surface of a random medium. In the Markov approximation, Mean square (MS) envelopes are calculated by using the Fourier transform of two-frequency mutual coherence function (TFMCF) with respect to the angular frequency. The TFMCF is statistically defined on the transverse plane, which is perpendicular to the global ray direction. The Fourier transform of the TFMCF with respect to the transverse coordinates gives the angular spectrum that shows the distribution of ray directions. This angular spectrum has a sharp peak in the global ray direction just after the direct wave arrival and gradually increases its width with the lapse time increasing. We can calculate vector-wave envelopes in the infinite space, simply projecting the angular spectrum to each component and integrating it in the wavenumber space. We calculate the vector-wave envelopes on the free surface by multiplying the

  3. Vorticity-based correction for modelling of free-surface wave interacting with turbulent current

    NASA Astrophysics Data System (ADS)

    Zhang, Wei

    2014-11-01

    This paper describes a new vorticity-based correction model for studying the interaction between free-surface wave and turbulent current. To track free-surface movements, the volume of fluid (VOF) method is employed. The momentum equations are rewritten to avoid the numerically generated vorticity effects along the air-water interface. Simultaneously unsteady RANS equations are used, while standard k-epsilon model is adapted with modification to the production term by introducing the vorticity to limit the production of turbulent kinematic energy at free surface. To validate the numerical model used here, standalone wave and current cases are studied to ensure the accuracy of each component of the numerical model. The model is then used to simulate the interaction between the second-order stokes wave and turbulent current for both wave following and countering in a setting of shallow water wave flume. The results are compared with experimental measurement available in the literature.

  4. 3D numerical simulation analysis of passive drag near free surface in swimming

    NASA Astrophysics Data System (ADS)

    Zhan, Jie-min; Li, Tian-zeng; Chen, Xue-bin; Li, Yok-sheung; Wai, Wing-hong Onyx

    2015-04-01

    The aim of this work is to build a 3D numerical model to study the characteristics of passive drag on competitive swimmers taking into account the impact of the free surface. This model solves the 3D incompressible Navier-Stokes equations using RNG k- ɛ turbulence closure. The volume of fluid (VOF) method is used to locate the free surface. The 3D virtual model is created by Computer Aided Industrial Design (CAID) software, Rhinoceros. Firstly, a specific posture of swimming is studied. The simulation results are in good agreement with the data from mannequin towing experiments. The effects of a swimmer's arms and legs positions on swimming performance are then studied. Finally, it is demonstrated that the present method is capable of simulating gliding near the free surface.

  5. Hydrogen, lithium, and lithium hydride production

    SciTech Connect

    Brown, Sam W; Spencer, Larry S; Phillips, Michael R; Powell, G. Louis; Campbell, Peggy J

    2014-03-25

    A method of producing high purity lithium metal is provided, where gaseous-phase lithium metal is extracted from lithium hydride and condensed to form solid high purity lithium metal. The high purity lithium metal may be hydrided to provide high purity lithium hydride.

  6. Reduced Viscosity of the Free Surface in Entangled Polymer Melt Films

    NASA Astrophysics Data System (ADS)

    Koga, Tadanori; Li, C.; Endoh, M. K.; Koo, J.; Rafailovich, M.; Narayanan, S.; Lee, D. R.; Lurio, L. B.; Sinha, S. K.

    2010-02-01

    By embedding “dilute” gold nanoparticles in single polystyrene thin films as “markers”, we probe the local viscosity of the free surface at temperatures far above the glass transition temperature (Tg). The technique used was x-ray photon correlation spectroscopy with resonance-enhanced x-ray scattering. The results clearly showed the surface viscosity is about 30% lower than the rest of the film. We found that this reduction is strongly associated with chain entanglements at the free surface rather than the reduction in Tg.

  7. Combustion theory for liquids with a free surface. 3: Special problems

    NASA Technical Reports Server (NTRS)

    Milkov, S. N.; Sukhov, G. S.; Yarin, L. P.

    1986-01-01

    Two special problems concerning the combustion of liquids with a free surface, i.e., flame quenching during the mixing of a burning liquid inside a container and liquid burnout from a porous layer, are analyzed using a quasi-one-dimensional model. The critical parameters corresponding to the quenching of a burning fluid with a free surface are determined. Determinations are also made of the limiting pressure gradients corresponding to the transition from the combustion mode where the liquid evaporates from the surface of a porous layer to the mode where the phase transition surface lies inside the porous layer.

  8. Curvature estimation from a volume-of-fluid indicator function for the simulation of surface tension and wetting with a free-surface lattice Boltzmann method

    NASA Astrophysics Data System (ADS)

    Bogner, Simon; Rüde, Ulrich; Harting, Jens

    2016-04-01

    The free surface lattice Boltzmann method (FSLBM) is a combination of the hydrodynamic lattice Boltzmann method with a volume-of-fluid (VOF) interface capturing technique for the simulation of incompressible free surface flows. Capillary effects are modeled by extracting the curvature of the interface from the VOF indicator function and imposing a pressure jump at the free boundary. However, obtaining accurate curvature estimates from a VOF description can introduce significant errors. This article reports numerical results for three different surface tension models in standard test cases and compares the according errors in the velocity field (spurious currents). Furthermore, the FSLBM is shown to be suited to simulate wetting effects at solid boundaries. To this end, a new method is developed to represent wetting boundary conditions in a least-squares curvature reconstruction technique. The main limitations of the current FSLBM are analyzed and are found to be caused by its simplified advection scheme. Possible improvements are suggested.

  9. Thermoelectric magnetohydrodynamic and thermocapillary driven flows of liquid conductors in magnetic fields

    NASA Astrophysics Data System (ADS)

    Jaworski, Michael Andrew

    The Solid/Liquid Lithium Divertor experiment (SLiDE) has been designed, constructed and operated in order to determine the behavior of these liquid conductors in a magnetic field with imposed thermal gradients. Liquid lithium is chosen for its applicability to fusion systems as well as recent demonstrations of its ability to passively redistribute incident heat fluxes on the order of 50[MW/m2]. The lithium is contained within a stainless steel tray that is actively cooled and contains a set of temperature diagnostics for analysis of the heat, flux coming from the tray. The system is magnetized by a set of external magnets and a linear electron beam is used to create heat fluxes similar to those found in fusion divertors. Surface velocity of the liquid lithium is measured with a digital camera. A theory explaining the balance between thermoelectric magnetohydrodynamics and thero-capillary driven, free-surface flows in containers of arbitrary type in a magnetized environment has been developed. A new dimensionless group depending on the thermoelectric power of the liquid/container pair, the physical properties of the liquid and solid and the flow geometry has been found that determines which mechanism, TC or TEMHD, is the dominant effect in any given system. Experiments show that TEMHD dominates the flow in SLiDE, consistent with the theory governing these flows. This is verified by series of qualitative experiments, as well as quantitative comparison with theoretical flow predictions. This constitutes the first direct observation of TEMHD driven flow yet reported in the literature. Application of the developed theory indicates liquid lithium fusion systems will operate in a TEMHD dominated regime. Technologies suggested by the exploitation of TEMHD pumping are also presented.

  10. Optimal dispersion with minimized Poisson equations for non-hydrostatic free surface flows

    NASA Astrophysics Data System (ADS)

    Cui, Haiyang; Pietrzak, J. D.; Stelling, G. S.

    2014-09-01

    A non-hydrostatic shallow-water model is proposed to simulate the wave propagation in situations where the ratio of the wave length to the water depth is small. It exploits the reduced-size stencil in the Poisson pressure solver to make the model less expensive in terms of memory and CPU time. We refer to this new technique as the minimized Poisson equations formulation. In the simplest case when the method applied to a two-layer model, the new model requires the same computational effort as depth-integrated non-hydrostatic models, but can provide a much better description of dispersive waves. To allow an easy implementation of the new method in depth-integrated models, the governing equations are transformed into a depth-integrated system, in which the velocity difference serves as an extra variable. The non-hydrostatic shallow-water model with minimized Poisson equations formulation produces good results in a series of numerical experiments, including a standing wave in a basin, a non-linear wave test, solitary wave propagation in a channel and a wave propagation over a submerged bar.

  11. Free-surface flow in horizontally rotating cylinder: experiment and simulation

    NASA Astrophysics Data System (ADS)

    Bohacek, J.; Kharicha, A.; Ludwig, A.; Wu, M.; Paar, A.; Brandner, M.; Elizondo, L.; Trickl, T.

    2016-07-01

    The horizontal centrifugal casting process targets on a liquid layer with a uniform thickness. To achieve this, the rotations of the mold have to be large enough so that the liquid can pick up the speed of the mold. In the present paper, an experiment was conducted using a laboratory plexi-glass mold with water as a working fluid. Starting with an initial volume fraction of liquid resting in the bottom of the mold, the mold rotations were gradually increased from 0 rpm to max rpm and a new position of the contact line was recorded. In addition, first critical rpm was recorded, at which the transition from the liquid pool to a uniform liquid layer occurred. While gradually going back from max rpm to 0 rpm, second critical rpm was recorded, at which the uniform liquid layer collapsed. The experiment was compared with the numerical simulation solving the modified shallow water equations using the Newton-Raphson method with the Wallington filter.

  12. Low gravity experiment for studying a rotating fluid having a free surface

    NASA Technical Reports Server (NTRS)

    Holderer, O. C.

    1983-01-01

    Electrical, mechanical, and operational aspects of a test cell assembly for studying rotating fluids with a free surface are described. Results of a stress analysis prepared to document the structural adequacy for safe use on the KC-135 aircraft are presented along with results of a single load proof test of the most critical load case. Engineering drawings are included.

  13. Lithium nephrotoxicity.

    PubMed

    Azab, Abed N; Shnaider, Alla; Osher, Yamima; Wang, Dana; Bersudsky, Yuly; Belmaker, R H

    2015-12-01

    Reports of toxic effects on the kidney of lithium treatment emerged very soon after lithium therapy was introduced. Lithium-induced nephrogenic diabetes insipidus is usually self-limiting or not clinically dangerous. Some reports of irreversible chronic kidney disease and renal failure were difficult to attribute to lithium treatment since chronic kidney disease and renal failure exist in the population at large. In recent years, large-scale epidemiological studies have convincingly shown that lithium treatment elevates the risk of chronic kidney disease and renal failure. Most patients do not experience renal side effects. The most common side effect of polyuria only weakly predicts increasing creatinine or reduced kidney function. Among those patients who do experience decrease in creatinine clearance, some may require continuation of lithium treatment even as their creatinine increases. Other patients may be able to switch to a different mood stabilizer medication, but kidney function may continue to deteriorate even after lithium cessation. Most, but not all, evidence today recommends using a lower lithium plasma level target for long-term maintenance and thereby reducing risks of severe nephrotoxicity. PMID:26043842

  14. Heat and mass transfer at a free surface with diabatic boundaries in a single-species system under microgravity conditions

    NASA Astrophysics Data System (ADS)

    Fuhrmann, Eckart; Dreyer, Michael E.

    2014-06-01

    In this paper, we analyzed the heat and mass transfer at a free surface under microgravity conditions. The SOURCE-II (Sounding Rocket COMPERE Experiment) experiment was performed on a suborbital flight in February 2012 from Esrange in North Sweden. It provided representative data with respect to solid, liquid, and vapor temperatures as well as the visible surface position. The objectives were to quantify the deformation of the free liquid surface and to correlate the apparent contact angle to a characteristic temperature difference between subcooled liquid and superheated wall. Furthermore, the influence of evaporation and condensation at the liquid/vapor interface and at the superheated wall must be taken into account to analyze heat and mass fluxes due to a characteristic temperature difference. In the following, we show evidently that the magnitude of the apparent contact angle depends on the exerted specific pressurizations of the vapor phase during the experiment and hence on the change in the saturation temperature at the free surface. The characteristic temperature difference is defined with respect to the wall temperature in the vicinity of the contact line and the saturation temperature. Therefore, apparent contact angle and temperature difference can be correlated and indicate a specific characteristic. Concerning the heat and mass transfer at the free liquid surface and the contact line, two different methods are presented to evaluate the net mass due to phase change within a certain time interval. In the first approach, the mass flow rate is calculated by means of the ideal gas law and its derivatives with respect to temperature and pressure. The second approach calculates the heat flux as well as the mass flux at the wall and in the region of the free liquid surface. In these cases, a specific heat transfer coefficient and a thermal boundary layer thickness are used.

  15. Free-surface microfluidic control of surface-enhanced Raman spectroscopy for the optimized detection of airborne molecules

    PubMed Central

    Piorek, Brian D.; Lee, Seung Joon; Santiago, Juan G.; Moskovits, Martin; Banerjee, Sanjoy; Meinhart, Carl D.

    2007-01-01

    We present a microfluidic technique for sensitive, real-time, optimized detection of airborne water-soluble molecules by surface-enhanced Raman spectroscopy (SERS). The method is based on a free-surface fluidic device in which a pressure-driven liquid microchannel flow is constrained by surface tension. A colloidal suspension of silver nanoparticles flowing through the microchannel that is open to the atmosphere absorbs gas-phase 4-aminobenzenethiol (4-ABT) from the surrounding environment. As surface ions adsorbed on the colloid nanoparticles are substituted by 4-ABT, the colloid aggregates, forming SERS “hot spots” whose concentrations vary predictably along the microchannel flow. 4-ABT confined in these hot spots produces SERS spectra of very great intensity. An aggregation model is used to account quantitatively for the extent of colloid aggregation as determined from the variation of the SERS intensity measured as a function of the streamwise position along the microchannel, which also corresponds to nanoparticle exposure time. This allows us to monitor simultaneously the nanoparticle aggregation process and to determine the location at which the SERS signal is optimized. PMID:18025462

  16. Electrochemical flow-based solution-solid growth of the Cu2O nanorod array: potential application to lithium ion batteries.

    PubMed

    Shin, Jeong Ho; Park, Sun Hwa; Hyun, Seung Min; Kim, Jeong Won; Park, Hyun Min; Song, Jae Yong

    2014-09-14

    The catalyzed solution-liquid-solid (SLS) growth has been well developed to synthesize semiconductor nanowires with controlled diameters. The SLS growth occurs in the longitudinal direction of nanowires, due to the directional anisotropy driven by the metal catalysts where chemical precursors are introduced. In the present study, we report a selective, template-free, and environmentally-friendly electrochemical flow-based solution-solid (electrochemical flow-SS) growth of the Cu2O nanorod array. The anisotropy for directional growth without any catalysts is generated by the electrical field in a flowing electrolyte of ultra-dilute CuSO4. The filamentary anisotropy originates from electric field enhancement on pyramidal nanocrystals in the electrolyte of low ionic conductivity (13 μS cm(-1)). The Cu2O and Cu nanorods are able to be selectively synthesized by controlling the electrolyte pH and oxygen dissolution into the electrolyte. The synthesized Cu2O nanorod array shows excellent electrochemical properties as an anode material for lithium-ion batteries; the specific capacities increase from 323 to 1206 mA h g(-1) during 500 cycles. The capacity enhancement is due to the phase transformation from Cu2O to CuO, nano-restructuring of nanorods into fragmented nanoparticles, and the progressive generation of an electroactive polymeric gel-like layer on the surface of the nanoparticles. The electrochemical flow-SS growth of Cu2O nanorods is expected to contribute to further development of other functional nanorods. PMID:25055242

  17. Analysis of a Free Surface Film from a Controlled Liquid Impinging Jet over a Rotating Disk Including Conjugate Effects, with and without Evaporation

    NASA Technical Reports Server (NTRS)

    Sankaran, Subramanian (Technical Monitor); Rice, Jeremy; Faghri, Amir; Cetegen, Baki M.

    2005-01-01

    A detailed analysis of the liquid film characteristics and the accompanying heat transfer of a free surface controlled liquid impinging jet onto a rotating disk are presented. The computations were run on a two-dimensional axi-symmetric Eulerian mesh while the free surface was calculated with the volume of fluid method. Flow rates between 3 and 15 1pm with rotational speeds between 50 and 200 rpm are analyzed. The effects of inlet temperature on the film thickness and heat transfer are characterized as well as evaporative effects. The conjugate heating effect is modeled, and was found to effect the heat transfer results the most at both the inner and outer edges of the heated surface. The heat transfer was enhanced with both increasing flow rate and increasing rotational speeds. When evaporative effects were modeled, the evaporation was found to increase the heat transfer at the lower flow rates the most because of a fully developed thermal field that was achieved. The evaporative effects did not significantly enhance the heat transfer at the higher flow rates.

  18. Development and application of a hierarchical system for digital particle image velocimetry to free-surface turbulence

    NASA Astrophysics Data System (ADS)

    Kumar, S.; Banerjee, S.

    1998-01-01

    measurement of visual motion," Int. J. Comput. Vision, 2, 283, (1987)]. However, the confidence-level-based smoothing technique for rigid body motions (continuous velocity fields) could not be applied to displacement estimates obtained at discrete points i.e., the particle locations. Instead, smoothing was performed over the area covered by each particle. The algorithm has been tested against direct numerical simulations of turbulent flows when the flow field is known and particle images have been generated from these with the addition of noise. Both the accuracy of motion estimation and the computation time are seen to improve as compared to conventional PIV methods. Finally, video images taken of particle motion on the free-surface of a channel flow have been used to determine the capabilities of the technique in an experimental study. The resulting spectra show a quasi-two-dimensional character of the free-surface turbulent flow field, which corresponds well with the direct numerical simulations.

  19. Segregation Behavior of Sulfur and Other Impurities onto the Free Surfaces of ED-NI Deposits

    NASA Technical Reports Server (NTRS)

    Panda, B.; Jerman, G.

    2001-01-01

    Most researchers attribute grain boundary embrittlement in electro-deposited nickel (ED-Ni) to the presence of small quantities of sulfur as an impurity. It occurs in a highly mobile form that segregates to the grain boundaries. Evaluation of sulfur segregation requires that a sample be fractured through the grain boundaries. However, this action may not always be possible. ED-Ni is inherently tough at ambient temperature, especially if a low level of sulfur was intentionally maintained. A new method was developed to study sulfur and other migrant species to the grain boundaries, which also migrate to free surfaces. A test specimen is heated by a quartz lamp within the sample preparation chamber, allowing the mobile species to migrate to polished free surfaces. There the mobile species are analyzed using X-ray photoelectron spectroscopy (XPS) also known as Electron Spectroscopy for Chemical Analysis (ESCA).

  20. Segregation Behavior of Sulfur and Other Impurities Onto the Free Surfaces of ED-Ni Deposits

    NASA Technical Reports Server (NTRS)

    Panda, Binayak; Jerman, Gregory; Gentz, Steven J. (Technical Monitor)

    2000-01-01

    Most researchers attribute grain boundary embrittlement in electro-deposited Nickel (ED-Ni) to the presence of small quantities of Sulfur as an impurity. It occurs in a highly mobile form that segregates to the grain boundaries. Evaluation of Sulfur segregation requires that a sample be fractured through the grain boundaries. However, this action may not always be possible. ED-Ni is inherently tough at ambient temperature, especially if a low level of Sulfur was intentionally maintained. A new method was developed to study Sulfur and other migrant species to the grain boundaries, which also migrate to free surfaces. A test specimen is heated by a quartz lamp within the sample preparation chamber, allowing the mobile species to migrate to polished free surfaces. There the mobile species are analyzed using X-ray photoelectron spectroscopy (XPS) also known as Electron Spectroscopy for Chemical Analysis (ESCA).

  1. Instability of a confined jet impinging on a water/air free surface

    NASA Astrophysics Data System (ADS)

    Bouchet, G.; Climent, E.; Maurel, A.

    2002-09-01

    Self-sustained oscillations in sinuous mode occur when a water jet impinges from below on a water/air free surface. Confined jet instability is experimentally investigated by image processing and velocity measurements. Despite small deformations of the surface, dynamic response of the jet provides unusual behaviour with comparable configurations (hole-tone, jet edge ...). The central feature is a bounded evolution of the oscillation frequency. Modal transitions are observed when physical parameters are varied. Each frequency jump is related to wavelength modification of the spatial pattern. Atypical evolution of the predominant length scale has to be connected to strong coupling with the weak deformations induced by the impinging jet on the free surface.

  2. Effects of different wave free surface approximations on the response of a TLP in deep water

    SciTech Connect

    Mekha, B.B.; Johnson, C.P.; Roesset, J.M.

    1994-12-31

    This paper is based on work conducted at the Offshore Technology Research Center to investigate the relative importance of different types of nonlinearities on the dynamic response of tension leg platforms. A time domain solution using Morison`s equation with several modifications and allowing to include or neglect various sources of nonlinearities was implemented and used in the dynamic analysis. This paper focuses on the non-linear effect of evaluating the wave forces up to the free surface using different approximate methods. A TLP hull model with time varying tendon forces is subjected to regular and irregular waves with and without current. The effects on calculating the wave kinematics up to the mean water level or up to the actual free surface, making use of various extrapolation or stretching techniques are then discussed.

  3. Rupture Dynamics Simulations Along Subduction Zones: Bimaterial Interfaces and Free Surface Interaction

    NASA Astrophysics Data System (ADS)

    Scala, A.; Vilotte, J. P.; Festa, G.

    2015-12-01

    Largest earthquakes occur along subduction zones, where normal and tangential stress coupling drives the earthquake rupture due to the geometry of the subduction interface between dissimilar materials and the interaction with waves reflected from free surface as the rupture propagates toward the trench. We numerically investigate these effects in the context of dynamic rupture simulations. We revisit the problem of in-plane interface rupture propagation between dissimilar elastic media, in the case of slip-weakening friction, by performing a numerical study using the Spectral Element Method with a non-smooth contact formulation. For classical slip-weakening friction, the problem is ill posed due to a missing length or time scale in the response of the frictional shear stress to dynamic normal stress perturbations. We first perform a parametric study of the regularization formulation proposed by Rubin and Ampuero (2007). We show that the dynamic regularization, driven by local slip rate does not allow for a proper modeling of the asymptotic rupture propagation. We propose a new regularization approach based on the non-local length scale, associated to the actual size of the process zone. Numerical results are shown to be consistent with mathematical modeling of dynamic interface rupture propagation with a process zone ahead of the rupture front. The numerical study is extended to inclined ruptures intersecting a free surface at different angles. We investigate interaction between rupture propagation and stress changes induced by waves reflected from the free surface, in the generation of large interface slip, transient healing and opening effects. Finally, preliminary in-plane dynamic simulations of the 2011 Tohoku earthquake, incorporating the along-dip structure and geometry of the subduction interface, are presented enlightening the role of the geometry of the bi-material interface and of the free surface in the rupture propagation and radiation.

  4. Liquid-crystalline polymer and block copolymer domain alignment controlled by free-surface segregation.

    PubMed

    Fukuhara, Kei; Fujii, Yasuyoshi; Nagashima, Yuki; Hara, Mitsuo; Nagano, Shusaku; Seki, Takahiro

    2013-06-01

    An orientational change from homeotropic to planar of liquid crystal (LC) mesogens and the microphase separation (MPS) domains is attained by the segregated skin layer at the free surface. This allows for an efficient in-plane photoalignment of the cylindrical domains. The surface segregation strategy is very simple and is therefore expected to open up new possibilities for the orientation control of various types of LC materials. PMID:23616365

  5. Mechanisms of fracture of the free surface of shock-compressed metals

    SciTech Connect

    Mokhova, V. V. Mikhailov, A. L.; Til’kunov, A. V.; Orlov, N. I.; Kanunova, L. I.; Bragunets, V. A.; Tkachenko, M. I.; Simakov, V. G.; Sokolov, S. S.; Podurets, A. M.

    2015-12-15

    The mechanisms of the ejection of aluminum and copper microparticles from the free surfaces of these metals have been studied under conditions of the escape of a moderate-intensity shock wave from a sample. The free surfaces of samples contained 0.7–0.9 mm deep artificial wells and protrusions simulating (on a greater scale of 10: 1) the natural surface roughness retained upon mechanical processing. The pressure in a shock-wave pulse at the base of a protrusion was controlled within P = 5–20 GPa (i.e., below the melting region), and the variable duration of pressure pulses was 0.02, 0.2, and 1 μs. Analysis of the free surfaces of postloaded samples showed that, for certain loading and roughness parameters, the ejection of metal from vertices of protruding ridges or pyramids (as a result of the longitudinal fracture) was about ten times greater than the amount of metal ejected in the form of cumulative jets from wells. The amount of ejected metal and the size distribution of metal microparticles were quantitatively characterized using “soft collecting targets” and by measuring mass losses of samples upon fracture.

  6. Spontaneous development of arcuate single-sided subduction in global 3-D mantle convection models with a free surface

    NASA Astrophysics Data System (ADS)

    Crameri, Fabio; Tackley, Paul J.

    2014-07-01

    We present temporally evolving 3-D global mantle convection models with single-sided subduction and a free surface in both 3-D Cartesian and fully spherical geometry. Special focus is given to the spontaneous development of three-dimensional structures at the surface and in the upper mantle. We find that an arcuate shape is the natural form for trenches and slabs. Cartesian models are used first to study the dynamic evolution of subduction zones, spreading ridges, and interconnected transform features. These experiments highlight the strong variation of spontaneously developing, arcuate slab curvature and subduction polarity along the trench strike. The spontaneous development of spreading ridges leads to lateral offsets between separated segments that are characterized by normal transform motion. Spherical models then allow insights into the evolution of plate tectonics on a sphere. Investigated are the spontaneous evolution of slab geometry, trench motion, and subduction-induced mantle flow. Two new dynamical features are discovered: "back-slab spiral flow" and "slab tunneling." 2014. American Geophysical Union. All Rights Reserved.

  7. The fabrication of a vanadium-stainless steel test section for MHD testing of insulator coatings in flowing lithium

    SciTech Connect

    Reed, C.B.; Mattas, R.F.; Smith, D.L.; Chung, H.; Tsai, H.-C.; Morgan, G.D.; Wille, G.W.; Johnson, W.R.; Young, C.

    1996-12-31

    To test the magnetohydrodynamic (MHD) pressure drop reduction performance of candidate insulator coatings for the ITER Vanadium/Lithium Breeding Blanket, a test section comprised of a V- 4Cr-4Ti liner inside a stainless steel pipe was designed and fabricated. Theoretically, the MHD pressure drop reduction benefit resulting, from an electrically insulating coating on a vanadium- lined pipe is identical to the benefit derived from an insulated pipe fabricated of vanadium alone. A duplex test section design consisting of a V alloy liner encased in a SS pressure boundary provided protection for vanadium from atmospheric contamination during operation at high temperature and obviated any potential problems with vanadium welding while also minimizing the amount of V alloy material required. From the MHD and insulator coating- point of view, the test section outer SS wall and inner V alloy liner can be modeled simply as a wall having a sandwich construction. Two 52.3 mm OD x 2.9 m long V-alloy tubes were fabricated by Century Tubes from 64 mm x 200 mm x 1245 mm extrusions produced by Teledyne Wah Chang. The test section`s duplex structure was subsequently fabricated at Century Tubes by drawing down a SS pipe (2 inch schedule 10) over one of the 53.2 mm diameter V tubes.

  8. Lubrication Flows.

    ERIC Educational Resources Information Center

    Papanastasiou, Tasos C.

    1989-01-01

    Discusses fluid mechanics for undergraduates including the differential Navier-Stokes equations, dimensional analysis and simplified dimensionless numbers, control volume principles, the Reynolds lubrication equation for confined and free surface flows, capillary pressure, and simplified perturbation techniques. Provides a vertical dip coating…

  9. Lithium Ion Battery Design and Safety

    NASA Technical Reports Server (NTRS)

    Au, George; Locke, Laura

    2001-01-01

    This viewgraph presentation makes several recommendations to ensure the safe and effective design of Lithium ion cell batteries. Large lithium ion cells require pressure switches and small cells require pressure disconnects and other safety devices with the ability to instantly interrupt flow. Other suggestions include specifications for batteries and battery chargers.

  10. Lithium-metal infused trenches (LiMIT) for heat removal in fusion devices

    NASA Astrophysics Data System (ADS)

    Ruzic, D. N.; Xu, W.; Andruczyk, D.; Jaworski, M. A.

    2011-10-01

    Observation of liquid lithium flow in metal trenches has been made using a lithium-metal infused trench (LiMIT) tile and is reported here. The flow is self-pumping and uses thermoelectric magnetohydrodynamics to remove heated lithium and replenish it at a lower temperature. Flow velocities have been measured and compared with theoretical predictions.

  11. A stable finite difference method for the elastic wave equation on complex geometries with free surfaces

    SciTech Connect

    Appelo, D; Petersson, N A

    2007-12-17

    The isotropic elastic wave equation governs the propagation of seismic waves caused by earthquakes and other seismic events. It also governs the propagation of waves in solid material structures and devices, such as gas pipes, wave guides, railroad rails and disc brakes. In the vast majority of wave propagation problems arising in seismology and solid mechanics there are free surfaces. These free surfaces have, in general, complicated shapes and are rarely flat. Another feature, characterizing problems arising in these areas, is the strong heterogeneity of the media, in which the problems are posed. For example, on the characteristic length scales of seismological problems, the geological structures of the earth can be considered piecewise constant, leading to models where the values of the elastic properties are also piecewise constant. Large spatial contrasts are also found in solid mechanics devices composed of different materials welded together. The presence of curved free surfaces, together with the typical strong material heterogeneity, makes the design of stable, efficient and accurate numerical methods for the elastic wave equation challenging. Today, many different classes of numerical methods are used for the simulation of elastic waves. Early on, most of the methods were based on finite difference approximations of space and time derivatives of the equations in second order differential form (displacement formulation), see for example [1, 2]. The main problem with these early discretizations were their inability to approximate free surface boundary conditions in a stable and fully explicit manner, see e.g. [10, 11, 18, 20]. The instabilities of these early methods were especially bad for problems with materials with high ratios between the P-wave (C{sub p}) and S-wave (C{sub s}) velocities. For rectangular domains, a stable and explicit discretization of the free surface boundary conditions is presented in the paper [17] by Nilsson et al. In summary

  12. Refraction Interferometry and Free-surface Multiples for Large-offset OBS Data

    NASA Astrophysics Data System (ADS)

    Schuster, G. T.; Bharadwaj, P.; McIntosh, K.

    2011-12-01

    We present successful results for applying refraction interferometry to ocean bottom seismic (OBS) data. The OBS data were recorded by six inline OBS stations with a 15 km station spacing and a source ship shooting every 150 meters; the maximum source offset from an OBS station is 181 km. Each virtual trace was created by correlating and stacking up to 150 trace pairs to create a super-virtual refraction arrival having a theoretical signal-to-noise ratio (SNR) enhancement of up to 12:1. Free-surface refraction multiples were also utilized to enhance the SNR of primary refractions and virtually double the number of OBS sites from six to twelve stations. Results show the successful reconstruction of far-offset traces out to a source-receiver offset of 120 km. The super-virtual traces increase the number of pickable first arrivals from approximately 1,600 to more than 3,100 for a subset of the OBS data where the source is only on one side of the recording stations. In addition, the head waves associated with the first-order free-surface multiples allow for the creation of six new common receiver gathers (CRGs) recorded at virtual OBS stations, located about 5 km from any of the actual OBS stations. These new traces double the number of OBS stations compared to the original survey and increases the number of pickable traces from 1600 to 6200. In summary, our results with this OBS data set demonstrate that refraction interferometry can more than triple the number of pickable first arrivals in long-offset traces. This suggests the possibility that the number of independent OBS stations can be increased by N-fold if the free-surface refraction multiples up to the Nth-order are of high SNR and if the recording time is appropriately lengthened.

  13. Non-aqueous carbon black suspensions for lithium-based redox flow batteries: rheology and simultaneous rheo-electrical behavior.

    PubMed

    Youssry, Mohamed; Madec, Lénaïc; Soudan, Patrick; Cerbelaud, Manuella; Guyomard, Dominique; Lestriez, Bernard

    2013-09-14

    We report on the rheological and electrical properties of non-aqueous carbon black (CB) suspensions at equilibrium and under steady shear flow. The smaller the primary particle size of carbon black is, the higher the magnitude of rheological parameters and the conductivity are. The electrical percolation threshold ranges seem to coincide with the strong gel rather than the weak gel rheological threshold ones. The simultaneous measurements of electrical properties under shear flow reveal the well-known breaking-and-reforming mechanism that characterises such complex fluids. The small shear rate breaks up the network into smaller agglomerates, which in turn transform into anisometric eroded ones at very high shear rates, recovering the network conductivity. The type of carbon black, its concentration range and the flow rate range are now precisely identified for optimizing the performance of a redox flow battery. A preliminary electrochemical study for a composite anolyte (CB/Li4Ti5O12) at different charge-discharge rates and thicknesses is shown. PMID:23892887

  14. Virtual maneuvering test in CFD media in presence of free surface

    NASA Astrophysics Data System (ADS)

    Hajivand, Ahmad; Mousavizadegan, S. Hossein

    2015-05-01

    Maneuvering oblique towing test is simulated in a Computational Fluid Dynamic (CFD) environment to obtain the linear and nonlinear velocity dependent damping coefficients for a DTMB 5512 model ship. The simulations are carried out in freely accessible OpenFOAM library with three different solvers, rasInterFoam, LTSInterFoam and interDyMFoam, and two turbulence models, k-ɛ and SST k-ω in presence of free surface. Turning and zig-zag maneuvers are simulated for the DTMB 5512 model ship using the calculated damping coefficients with CFD. The comparison of simulated results with the available experimental shows a very good agreement among them.

  15. Virtual maneuvering test in CFD media in presence of free surface

    NASA Astrophysics Data System (ADS)

    Hajivand, Ahmad; Mousavizadegan, S. Hossein

    2015-09-01

    Maneuvering oblique towing test is simulated in a Computational Fluid Dynamic (CFD) environment to obtain the linear and nonlinear velocity dependent damping coefficients for a DTMB 5512 model ship. The simulations are carried out in freely accessible OpenFOAM library with three different solvers, rasInterFoam, LTSInterFoam and interDyMFoam, and two turbulence models, k-ɛ and SST k-ω in presence of free surface. Turning and zig-zag maneuvers are simulated for the DTMB 5512 model ship using the calculated damping coefficients with CFD. The comparison of simulated results with the available experimental shows a very good agreement among them.

  16. Chevron Defect at the Intersection of Grain Boundaries with Free Surfaces in Au

    NASA Astrophysics Data System (ADS)

    Radetic, T.; Lançon, F.; Dahmen, U.

    2002-08-01

    We have identified a new defect at the intersection between grain boundaries and surfaces in Au using atomic resolution transmission electron microscopy. At the junction line of 90° <110> tilt grain boundaries of (110)-(001) orientation with the free surface, a small segment of the grain boundary, about 1nm in length, dissociates into a triangular region with a chevronlike stacking disorder and a distorted hcp structure. The structure and stability of these defects are confirmed by atomistic simulations, and we point out the relationship with the one-dimensional incommensurate structure of the grain boundary.

  17. Gap Test Simulation and Measurement of Particle, Free Surface, and Shock Velocity Time Histories

    NASA Astrophysics Data System (ADS)

    Sutherland, Gerrit; Benjamin, Richard; Zellner, Michael; Sandusky, Harold

    2013-06-01

    We measured particle, free surface, and shock velocity time histories for the Plexiglas gap in two gap test arrangements. The two arrangements of gap tests were the large scale gap test (LSGT) and the expanded large scale gap test (ELSGT). Also, we used these velocity histories to validate gap test simulations. To acquire the data, we used a photonic Doppler velocimeter. The history data allowed us to find peak pressures for various gap lengths. Both LSGT and ELSGT peak pressures were closer to those predicted using the ELSGT calibration than the LSGT calibration. Also, we found agreement between our shock velocity histories and those obtained by Tasker and Baker.

  18. Capillary waves in an inhomogeneous three-layer liquid with a free surface

    NASA Astrophysics Data System (ADS)

    Shiryaeva, S. O.; Grigor'ev, A. I.; Zav'yalov, D. A.

    2016-06-01

    In the domain of capillary waves, a bicubic dispersion relation is derived and analyzed for surface and internal capillary-gravitational waves in a three-layer liquid with a free surface. It is shown that the ratio of the internal wave amplitudes to the surface wave amplitudes is fairly large if the trivial condition of a "homogeneous liquid" is discarded. The amplitude ratio between the internal waves themselves (generated at different interfaces) may be both greater and smaller than unity depending on the physical parameters of the system. Specifically, it strongly depends on the densities of the layers and their thicknesses.

  19. A calculation method for finite depth free-surface green function

    NASA Astrophysics Data System (ADS)

    Liu, Yingyi; Iwashita, Hidetsugu; Hu, Changhong

    2015-06-01

    An improved boundary element method is presented for numerical analysis of hydrodynamic behavior of marine structures. A new algorithm for numerical solution of the finite depth free-surface Green function in three dimensions is developed based on multiple series representations. The whole range of the key parameter R/h is divided into four regions, within which different representation is used to achieve fast convergence. The well-known epsilon algorithm is also adopted to accelerate the convergence. The critical convergence criteria for each representation are investigated and provided. The proposed method is validated by several well-documented benchmark problems.

  20. Chevron defect at the intersection of grain boundaries with free surfaces in Au.

    PubMed

    Radetic, T; Lançon, F; Dahmen, U

    2002-08-19

    We have identified a new defect at the intersection between grain boundaries and surfaces in Au using atomic resolution transmission electron microscopy. At the junction line of 90 degrees <110> tilt grain boundaries of (110)-(001) orientation with the free surface, a small segment of the grain boundary, about 1 nm in length, dissociates into a triangular region with a chevronlike stacking disorder and a distorted hcp structure. The structure and stability of these defects are confirmed by atomistic simulations, and we point out the relationship with the one-dimensional incommensurate structure of the grain boundary. PMID:12190479

  1. Nonlinear waves on the free surface of a dielectric liquid in an oblique electric field

    SciTech Connect

    Gashkov, M. A.; Zubarev, N. M. Kochurin, E. A.

    2015-09-15

    The nonlinear dynamics of the free surface of an ideal dielectric liquid that is exposed to an external oblique electric field has been studied theoretically. In the framework of the Hamiltonian formalism, a system of nonlinear integro-differential equations has been derived that describes the dynamics of nonlinear waves in the small-angle approximation. It is established that for a liquid with high dielectric permittivity, these equations have a solution in the form of plane waves of arbitrary shape that propagate without distortion in the direction of the horizontal component of the external field.

  2. Simulation of bubble expansion and collapse in the vicinity of a free surface

    NASA Astrophysics Data System (ADS)

    Koukouvinis, P.; Gavaises, M.; Supponen, O.; Farhat, M.

    2016-05-01

    The present paper focuses on the numerical simulation of the interaction of laser-generated bubbles with a free surface, including comparison of the results with instances from high-speed videos of the experiment. The Volume Of Fluid method was employed for tracking liquid and gas phases while compressibility effects were introduced with appropriate equations of state for each phase. Initial conditions of the bubble pressure were estimated through the traditional Rayleigh Plesset equation. The simulated bubble expands in a non-spherically symmetric way due to the interference of the free surface, obtaining an oval shape at the maximum size. During collapse, a jet with mushroom cap is formed at the axis of symmetry with the same direction as the gravity vector, which splits the initial bubble to an agglomeration of toroidal structures. Overall, the simulation results are in agreement with the experimental images, both quantitatively and qualitatively, while pressure waves are predicted both during the expansion and the collapse of the bubble. Minor discrepancies in the jet velocity and collapse rate are found and are attributed to the thermodynamic closure of the gas inside the bubble.

  3. Migration of free-surface-related multiples: Removing artefacts using a water-layer model

    NASA Astrophysics Data System (ADS)

    Hu, Hao; Wang, Yibo; Chang, Xu; Xie, Songlei

    2015-01-01

    The migration of free-surface-related multiples has been developed for seismic data processing because such multiples can be utilised for imaging and sometimes provide additional subsurface illumination. Recently, the simultaneous migration of primaries and free-surface-related multiples has been proposed as an attractive approach for avoiding the costly prediction of multiples. However, the migration artefacts of multiples, generated by mismatched events, pollute the stacked image and degrade the image quality. We developed a new approach to attenuate the distinct migration artefacts of multiples using water-layer-related multiples. In addition to the original data, the only additional information required by this approach is the water-layer model, which can be acquired easily and accurately from sonar or the stacked profile. By using the predicted water-layer multiples, the distinct migration artefacts can be imaged and then subtracted from the migration image of multiples. Numerical experiments illustrate that the proposed approach can suppress most distinct artefacts in the migration of multiples while preserving the advantages. The proposed approach is an effective tool for the removal of artefacts from the migration of multiples and can be applied to different types of migration operators to produce better-illuminated images with fewer artefacts.

  4. Asymmetric material impact: Achieving free surfaces velocities nearly double that of the projectile

    SciTech Connect

    Aslam, Tariq; Dattelbaum, Dana; Gustavsen, Richard; Scharff, Robert; Byers, Mark

    2015-05-19

    Hypervelocity impact speeds are often limited by practical considerations in guns and explosive driven systems. In particular, for gas guns (both powder driven and light gas guns), there is the general trend that higher projectile speeds often come at the expense of smaller diameters, and thus less time for examining shock phenomena prior to two dimensional release waves affecting the observed quantities of interest. Similarly, explosive driven systems have their own set of limiting conditions due to limitations in explosive energy and size of devices required as engineering dimensions increase. The focus in this study is to present a methodology of obtaining free surface velocities well in excess of the projectile velocity. The key to this approach is in using a high impedance projectile that impacts a series of progressively lower impedance materials. The free surface velocity (if they were separated) of each of the progressively lower impedance materials would increase for each material. The theory behind this approach, as well as experimental results are presented.

  5. Asymmetric material impact: Achieving free surfaces velocities nearly double that of the projectile

    DOE PAGESBeta

    Aslam, Tariq; Dattelbaum, Dana; Gustavsen, Richard; Scharff, Robert; Byers, Mark

    2015-05-19

    Hypervelocity impact speeds are often limited by practical considerations in guns and explosive driven systems. In particular, for gas guns (both powder driven and light gas guns), there is the general trend that higher projectile speeds often come at the expense of smaller diameters, and thus less time for examining shock phenomena prior to two dimensional release waves affecting the observed quantities of interest. Similarly, explosive driven systems have their own set of limiting conditions due to limitations in explosive energy and size of devices required as engineering dimensions increase. The focus in this study is to present a methodologymore » of obtaining free surface velocities well in excess of the projectile velocity. The key to this approach is in using a high impedance projectile that impacts a series of progressively lower impedance materials. The free surface velocity (if they were separated) of each of the progressively lower impedance materials would increase for each material. The theory behind this approach, as well as experimental results are presented.« less

  6. The reflection of low energy phonons at the free surface of liquid4He. II. Experiment

    NASA Astrophysics Data System (ADS)

    Baddar, H.; Edwards, D. O.

    1996-09-01

    Using a heater and bolometer as source and detector, the reflection of a pulsed beam of phonons at the free surface of liquid4He at ˜ 0.05 K has been measured for angles of incidence between 30 ° and 80 °. The energy distribution of the incident beam was obtained from the theory of phonon decay in the accompanying paper (I). The average incident phonon energy was ˜ 0.3 K, corresponding to an effective beam temperature of about 0.1 K. Both heater and bolometer were made from graphite resistor board with a layer of poly aniline fibers to increase the absorptivity for rotons. The angular distribution of the phonons from the heater is quite broad, approximately (cosn π+cosm θ)/2 with n ≈ 0.65 and m ≈ 3.4. However, the receiver response has a broad component with n ≈ 2.2 and an extraordinarily narrow one with m ≈ 106. In agreement with the theory in I, the reflection appears to be specular within the accuracy of the experiment. The reflection coefficient is unity within the experimental error; the weighted mean value is 1.001±0.025. During the experiment, the free surface became contaminated with ˜ 0.034 of a monolayer of3He, but no effect from the3He impurity was observed.

  7. Numerical simulation of Marangoni flow in partially confined half-zone liquid bridge of low-Prandtl-number fluids

    NASA Astrophysics Data System (ADS)

    Shiratori, Suguru; Yasuhiro, Shouichi; Hibiya, Taketoshi

    2004-05-01

    Direct numerical simulation using a finite difference method was done to reveal the fundamental characteristics of the flow in a half-zone liquid bridge of low Prandtl number fluids with the free surface partially confined by oxide films (non-slip adiabatic rigid walls). The critical Marangoni number Mac1 was calculated for several geometries, which are determined by the free surface ratio ( ξ= Lw/ L, Lw: length of the free surface, L: height of the whole liquid bridge) and the axial position of the free surface. When the oxide film exists between the free surface and the cold disc, the flow separates from the oxide film, and a weak cell with a counter flow arises near the cold disc. An axisymmetric flow exhibits a direct transition to an oscillatory flow, when the free surface ratio ξ is sufficiently small and free surface was located away from the cold disc.

  8. Experimental study on the interaction between bubble and free surface using a high-voltage spark generator

    NASA Astrophysics Data System (ADS)

    Zhang, S.; Wang, S. P.; Zhang, A. M.

    2016-03-01

    The experimental studies presented in this paper attempt to supply a reasonable comprehensive explanation for the key feature of the collapse bubble and the complex nature of the raised free surface. Six distinctive patterns of free surface motion were identified for bubbles initiated at different γf (the non-dimensional bubble-free surface distance scaled with the maximum bubble radius). Special features such as "breaking wrinkles," "spraying water film," and other unstable phenomena were observed with free surface motions, which were hardly captured by a boundary integral scheme. Parameters defining the shape of the free surface, such as the spike height Hspike, the spike width Wbase, and the skirt height Hspray, are measured and analyzed against γf. Different voltages were used to generate bubbles with varies sizes, while the bubble and free surface motion patterns appeared to be largely independent of the bubble size. Finally, collapsing bubble shape, centroid migration, period of bubble oscillation, and jet tip velocity at different γf are investigated and noticeable variation trends are found.

  9. Spontaneous development of arcuate single-sided subduction in global 3-D mantle convection models with a free surface

    NASA Astrophysics Data System (ADS)

    Crameri, Fabio; Tackley, Paul

    2014-05-01

    The work presented aims at a better understanding of plate tectonics, a crucial dynamical feature within the global framework of mantle convection. Special focus is given to the interaction of subduction-related mantle flow and surface topography. Thereby, the application of a numerical model with two key functional requirements is essential: an evolution over a long time period to naturally model mantle flow and a physically correct topography calculation. The global mantle convection model presented in Crameri et al. (2012a) satisfies both of these requirements. First, it is efficiently calculated by the finite-volume code Stag-YY (e.g., Tackley 2008) using a multi-grid method on a fully staggered grid. Second, it applies the sticky-air method (Matsumoto and Tomoda 1983; Schmeling et al, 2008) and thus approximates a free surface when the sticky-air parameters are chosen carefully (Crameri et al., 2012b). This leads to dynamically self-consistent mantle convection with realistic, single-sided subduction. New insights are thus gained into the interplay of obliquely sinking plates, toroidal mantle flow and the arcuate shape of slabs and trenches. Numerous two-dimensional experiments provide optimal parameter setups that are applied to three-dimensional models in Cartesian and fully spherical geometries. Features observed and characterised in the latter experiments give important insight into the strongly variable behaviour of subduction zones along their strike. This includes (i) the spontaneous development of arcuate trench geometry, (ii) regional subduction polarity reversals and slab tearing, and the newly discovered features (iii) 'slab tunnelling' and (iv) 'back-slab spiral flow'. Overall, this study demonstrates the strong interaction between surface topography and mantle currents and highlights the variability of subduction zones and their individual segments. REFERENCES Crameri, F., P. J. Tackley, I. Meilick, T. V. Gerya, and B. J. P. Kaus (2012a), A free

  10. Convective Stirring in Liquid Lithium (LTX)

    NASA Astrophysics Data System (ADS)

    Cassin, Margaret; Kearns, Eugene; Majeski, Richard

    2011-10-01

    LTX is a spherical tokamak with R=0.4 m, a=0.26 m, and elongation=1.5. LTX has a heated (300 - 400 C) liner, designed to be coated with lithium. During experiments in 2010, oxidation of the lithium surface was observed when the liner was heated to 300 C, above the melting point of lithium (182 C). A pumping system is being installed to absorb and pump background gasses which react with lithium, similar to a getter pump, using liquid and solid lithium. Lithium will be loaded into a yttria crucible heated from below by a small, HeatWave model TB175 300W cartridge heater to produce convective currents in order to maintain a clean lithium surface and decrease the time for oxide formation. This system was tested in an argon glove box using a copper heat concentrator - instead of the HeatWave vacuum-compatible unit. Infrared thermometry and thermocouples were used to monitor the surface temperature of the molten lithium, and convective flow patterns. A 200 FPS high speed camera was also employed to monitor flows, using the motion of residual oxide patches. Results from the measurements will be presented. Supported by US DOE contract DE-AC02-09CH11466.

  11. Experimental investigations of capillary effects on nonlinear free-surface waves

    NASA Astrophysics Data System (ADS)

    Diorio, James D.

    This thesis presents the results of three experiments on various aspects of the effects of surface tension on nonlinear free-surface waves. The first two experiments focus on capillary effects on the breaking of short-wavelength gravity waves, a problem of interest in areas of physical oceanography and remote sensing. The third experiment is concerned with the bifurcation of solitary capillary-gravity waves, a problem that is relevant in the study of nonlinear, dispersive wave systems. In the first set of experiments, streamwise profile measurements were made of spilling breakers at the point of incipient breaking. Both wind-waves and mechanically generated waves were investigated in this study, with gravity wavelengths in the range of 10--120 cm. Although it has been previously argued that the crest shape is dependent only on the surface tension, the results reported herein are to the contrary as several geometrical parameters used to describe the crest change significantly with the wavelength. However, the non-dimensional crest shape is self-similar, with two-shape parameters that depend on a measure of the local wave slope. This self-similarity persists over the entire range of wavelengths and breaker conditions measured, indicating a universal behavior in the near-crest dynamics that is independent of the method used to generate the wave. The measured wave slope is found to be related to the wave growth rate and phase-speed prior to breaking, a result that contributes towards the development of a breaking criterion for unsteady capillary-gravity waves. The second set of experiments examines the cross-stream surface structure in the turbulent breaking zone generated by short-wavelength breakers. Waves in this study were generated using a mechanical wedge and ranged in wavelength from 80--120 cm. To isolate the effects of surface tension on the flow, the important experimental parameters were adjusted to produce Froude-scaled, dispersively-focused wave packets

  12. Lithium in 2012

    USGS Publications Warehouse

    Jaskula, B.W.

    2013-01-01

    In 2012, estimated world lithium consumption was about 28 kt (31,000 st) of lithium contained in minerals and compounds, an 8 percent increase from that of 2011. Estimated U.S. consumption was about 2 kt (2,200 st) of contained lithium, the same as that of 2011. The United States was thought to rank fourth in consumption of lithium and remained the leading importer of lithium carbonate and the leading producer of value-added lithium materials. One company, Rockwood Lithium Inc., produced lithium compounds from domestic brine resources near Silver Peak, NV.

  13. Evaporation model for beam based additive manufacturing using free surface lattice Boltzmann methods

    NASA Astrophysics Data System (ADS)

    Klassen, Alexander; Scharowsky, Thorsten; Körner, Carolin

    2014-07-01

    Evaporation plays an important role in many technical applications including beam-based additive manufacturing processes, such as selective electron beam or selective laser melting (SEBM/SLM). In this paper, we describe an evaporation model which we employ within the framework of a two-dimensional free surface lattice Boltzmann method. With this method, we solve the hydrodynamics as well as thermodynamics of the molten material taking into account the mass and energy losses due to evaporation and the recoil pressure acting on the melt pool. Validation of the numerical model is performed by measuring maximum melt depths and evaporative losses in samples of pure titanium and Ti-6Al-4V molten by an electron beam. Finally, the model is applied to create processing maps for an SEBM process. The results predict that the penetration depth of the electron beam, which is a function of the acceleration voltage, has a significant influence on evaporation effects.

  14. A hybrid method for computing forces on curved dislocations threading to free surfaces

    SciTech Connect

    Tang, M; Cai, W; Xu, G; Bulatov, V V

    2005-06-06

    Dislocations threading to free surfaces present a challenge for numerical implementation of traction-free boundary conditions. The difficulty arises when canonical (singular) solutions of dislocation mechanics are used in combination with the Finite Element or Boundary Element (Green's function) methods. A new hybrid method is developed here in which the singular part and the non-singular (regular) part of the image stress are dealt with separately. A special analytical solution for a semi-infinite straight dislocation intersecting the surface of a half-space is used to account for the singular part of the image stress, while the remaining regular part of the image stress field is treated using the standard Finite Element Method. The numerical advantages of such regularization are demonstrated with examples.

  15. Pb-free surface-finishing on electronic components' terminals for Pb-free soldering assembly

    SciTech Connect

    Tanaka, Hitoshi; Tanimoto, Morimasa; Matsuda, Akira; Uno, Takeo; Kurihara, Masaaki; Shiga, Shoji

    1999-11-01

    Pb-free solderable surface finishing is essential to implement Pb-free solder assembly in order to meet with the growing demand of environmental consciousness to eliminate Pb from electronic products. Two types of widely applicable Pb-free surface finishing technologies are developed. One is the multilayer-system including Pd with Ni undercoat. Heat-resistance of Pd enables whole-surface-plating on to leadframe before IC-assembling process. The other is the double-layer-system with low-melting-point-materials, for example, thicker Sn underlayer and thinner Sn-Bi alloy overlayer, dilutes Sn-Bi alloy's defects of harmful reactivity along with substrate metal and mechanical brittleness with keeping its advantages of solder-wettability and no whisker.

  16. Free-surface molecular command systems for photoalignment of liquid crystalline materials.

    PubMed

    Fukuhara, Kei; Nagano, Shusaku; Hara, Mitsuo; Seki, Takahiro

    2014-01-01

    The orientation of liquid crystal molecules is very sensitive towards contacting surfaces, and this phenomenon is critical during the fabrication of liquid crystal display panels, as well as optical and memory devices. To date, research has focused on designing and modifying solid surfaces. Here we report an approach to control the orientation of liquid crystals from the free (air) surface side: a skin layer at the free surface was prepared using a non-photoresponsive liquid crystalline polymer film by surface segregation or inkjet printing an azobenzene-containing liquid crystalline block copolymer. Both planar-planar and homoeotropic-planar mode patterns were readily generated. This strategy is applicable to various substrate systems, including inorganic substrates and flexible polymer films. These versatile processes require no modification of the substrate surface and are therefore expected to provide new opportunities for the fabrication of optical and mechanical devices based on liquid crystal alignment. PMID:24534881

  17. Motion of free-surface of shock-compressed water on emergence of rarefaction

    NASA Astrophysics Data System (ADS)

    Menezes, V.; Hosseini, H.; Moosavi-Nejad, S.; Irimpan, K. J.; Akiyama, H.

    2015-10-01

    We experimentally evaluated the impulsive motion of free-surface of water on impingement of shock-waves of moderate strength. This physical process creates the initial acceleration in shock-wave based micro-fluidic devices, which have promising medical and drug/DNA delivery applications. The velocities of the water interfaces were measured through real-time high-temporal/spatial resolution visualizations. Based on modified Tait equation-of-state and the concept of Reimann-invariants, an analytical expression was deduced to calculate the particle velocity behind the unloading wave. The experiments and analyses confirm that the mass motion behind the shock-wave accelerates to very high velocities, a requirement for effective momentum delivery in micro-jet devices.

  18. A communication-avoiding implicit-explicit method for a free-surface ocean model

    NASA Astrophysics Data System (ADS)

    Newman, Christopher; Womeldorff, Geoffrey; Knoll, Dana A.; Chacón, Luis

    2016-01-01

    We examine a nonlinear elimination method for the free-surface ocean equations based on barotropic-baroclinic decomposition. The two dimensional scalar continuity equation is treated implicitly with a preconditioned Jacobian-free Newton-Krylov method (JFNK). The remaining three dimensional equations are subcycled explicitly within the JFNK residual evaluation with a method known as nonlinear elimination. In this approach, the memory footprint of the underlying Krylov vector is greatly reduced over that required by fully coupled implicit methods. The method is second-order accurate and scales algorithmically, with allowed timesteps much larger than fully explicit methods. Moreover, the hierarchical nature of the algorithm lends itself readily to emerging architectures. In particular, we introduce a communication staging strategy for the three dimensional explicit system that greatly reduces the communication costs of the algorithm and provides a key advantage as communication costs continue to dominate relative to floating point costs in emerging architectures.

  19. Free-surface molecular command systems for photoalignment of liquid crystalline materials

    PubMed Central

    Fukuhara, Kei; Nagano, Shusaku; Hara, Mitsuo; Seki, Takahiro

    2014-01-01

    The orientation of liquid crystal molecules is very sensitive towards contacting surfaces, and this phenomenon is critical during the fabrication of liquid crystal display panels, as well as optical and memory devices. To date, research has focused on designing and modifying solid surfaces. Here we report an approach to control the orientation of liquid crystals from the free (air) surface side: a skin layer at the free surface was prepared using a non-photoresponsive liquid crystalline polymer film by surface segregation or inkjet printing an azobenzene-containing liquid crystalline block copolymer. Both planar-planar and homoeotropic-planar mode patterns were readily generated. This strategy is applicable to various substrate systems, including inorganic substrates and flexible polymer films. These versatile processes require no modification of the substrate surface and are therefore expected to provide new opportunities for the fabrication of optical and mechanical devices based on liquid crystal alignment. PMID:24534881

  20. Step Free Surface Heteroepitaxy of 3C-SiC Layers on Patterned 4H/6H-SiC Mesas and Cantilevers

    NASA Technical Reports Server (NTRS)

    Neudeck, Philip G.; Powell, J. Anthony; Trunek, Andrew J.; Spry, David J.

    2003-01-01

    Most SiC devices are implemented in homoepitaxial films grown on 4H/6H-SiC wafers with surfaces 3 degrees to 8 degrees off-axis from the (0001) basal plane. This approach has not prevented many substrate crystal defects from propagating into SiC epilayers, and does not permit the realization of SiC heteropolytype devices. This presentation describes recent advances in SiC epitaxial growth that begun to overcome the above shortcomings for arrays of mesas patterned into on-axis 4H/6H-SiC wafers. First, we demonstrated that atomic-scale surface steps can be completely eliminated from 4H/6H-SiC mesas via on-axis homoepitaxial step-flow growth, forming (0001) basal plane surfaces (up to 0.4 mm x 0.4 mm) for larger than previously thought possible. Step-free surface areas were then extended by growth fo thin lateral cantilevers from the mesa tops. These lateral cantilevers enabled substrate defects to be reduced and relocated in homoepitaxial films in a manner not possible with off-axis SiC growth. Finally, growth of vastly improved 3C-SiC heterofilms was achieved on 4H/6H-SiC mesas using the recently develop step-free surface heteroepitaxy process. These epitaxial growth developments should enable improved homojunction and heterojunction silicon carbide prototype devices.

  1. Free-surface temperature measurement of shock-loaded tin using ultrafast infrared pyrometry

    NASA Astrophysics Data System (ADS)

    Mondot, Michel; Remiot, Christian

    1991-11-01

    The main problem regarding free surface temperature measurement by infrared pyrometry is the lack of emissivity data of shocked materials. Moreover, the short rise time in an hydrodynamic experiment requires particular detectors and experimental measurement technique. This paper describes a three channel pyrometer adapted to the study of shocked tin sample melted in release. The radiative infrared emission is collected by ZnSe lens and carried from the firing chamber to the pyrometer by fluoride glass optical fiber. In order to deduce the temperature from the electrical signals amplified before recording on a numerical oscilloscope, we use different narrow filters associated with a previous static calibration of the detectors by means of a continuously heated black body. The spectral integration of Planck's formula and the comparison between the static calibration with the black body and the dynamic signals give, for each experiment, three temperature-emissivity couples in agreement with Planck's theory. The originality of this measurement technique is the use of a 15 meter infrared optical triple core fiber for transporting the radiation from the target to the detectors, which simultaneously permits the measurement of three temperature-emissivity couples in the case of very small and hermetic experimental set-up. The main characteristics of this pyrometer are: a rise time of about 20 nanoseconds; an analysis area with a diameter smaller than 5 millimeters; continuous free surface temperature measurement during more than 5 microseconds; and the study of the wavelengths between 2 and 5 micrometers. Experiments have been achieved with optical polished tin samples. The abacus voltages, temperature, and emissivity versus time for a 45 GPa shock pressure is discussed.

  2. Comparison of H-Mode Plasmas Diverted to Solid and Liquid Lithium Surfaces

    SciTech Connect

    R. Kaita, et. al.

    2012-07-20

    Experiments were conducted with a Liquid Lithium Divertor (LLD) in NSTX. Among the goals was to use lithium recoating to sustain deuterium (D) retention by a static liquid lithium surface, approximating the ability of flowing liquid lithium to maintain chemical reactivity. Lithium evaporators were used to deposit lithium on the LLD surface. Improvements in plasma edge conditions were similar to those with lithiated graphite plasma-facing components (PFCs), including an increase in confinement over discharges without lithiumcoated PFCs and ELM reduction during H-modes. With the outer strike point on the LLD, the D retention in the LLD was about the same as that for solid lithium coatings on graphite, or about two times that achieved without lithium PFC coatings. There were also indications of contamination of the LLD surface, possibly due erosion and redeposition of carbon from PFCs. Flowing lithium may thus be needed for chemically active PFCs during long-pulse operation.

  3. The lithium vapor box divertor

    NASA Astrophysics Data System (ADS)

    Goldston, R. J.; Myers, R.; Schwartz, J.

    2016-02-01

    It has long been recognized that volumetric dissipation of the plasma heat flux from a fusion power system is preferable to its localized impingement on a material surface. Volumetric dissipation mitigates both the anticipated very high heat flux and intense particle-induced damage due to sputtering. Recent projections to a tokamak demonstration power plant suggest an immense upstream parallel heat flux, of order 20 GW m-2, implying that fully detached operation may be a requirement for the success of fusion power. Building on pioneering work on the use of lithium by Nagayama et al and by Ono et al as well as earlier work on the gas box divertor by Watkins and Rebut, we present here a concept for a lithium vapor box divertor, in which lithium vapor extracts momentum and energy from a fusion-power-plant divertor plasma, using fully volumetric processes. At the high powers and pressures that are projected this requires a high density of lithium vapor, which must be isolated from the main plasma in order to avoid lithium build-up on the chamber walls or in the plasma. Isolation is achieved through a powerful multi-box differential pumping scheme available only for condensable vapors. The preliminary box-wise calculations are encouraging, but much more work is required to demonstrate the practical viability of this scheme, taking into account at least 2D plasma and vapor flows within and between the vapor boxes and out of the vapor boxes to the main plasma.

  4. Fluid flow over arbitrary bottom topography in a channel

    NASA Astrophysics Data System (ADS)

    Panda, Srikumar

    2016-05-01

    In this paper, two-dimensional free surface potential flow over an arbitrary bottom in a channel is considered to analyze the behavior of the free surface profile using linear theory. It is assumed that the fluid is inviscid, incompressible and flow is irrotational. Perturbation analysis in conjunction with Fourier transform technique is employed to determine the first order corrections of some important physical quantities such as free surface profile, velocity potential, etc. From the practical point of view, one arbitrary bottom topography is considered to determine the free surface profile since the free surface profile depends on the bottom topography. It is found that the free surface profile is oscillatory in nature, representing a wave propagating downstream and no wave upstream.

  5. Lithium-associated hyperthyroidism.

    PubMed

    Siyam, Fadi F; Deshmukh, Sanaa; Garcia-Touza, Mariana

    2013-08-01

    Goiters and hypothyroidism are well-known patient complications of the use of lithium for treatment of bipolar disease. However, the occurrence of lithium-induced hyperthyroidism is a more rare event. Many times, the condition can be confused with a flare of mania. Monitoring through serial biochemical measurement of thyroid function is critical in patients taking lithium. Hyperthyroidism induced by lithium is a condition that generally can be controlled medically without the patient having to discontinue lithium therapy, although in some circumstances, discontinuation of lithium therapy may be indicated. We report on a patient case of lithium-associated hyperthyroidism that resolved after discontinuation of the medication. PMID:23948626

  6. Thermal migration of deuterium implanted in graphite: Influence of free surface proximity and structure

    NASA Astrophysics Data System (ADS)

    Le Guillou, M.; Moncoffre, N.; Toulhoat, N.; Pipon, Y.; Ammar, M. R.; Rouzaud, J. N.; Deldicque, D.

    2016-03-01

    This paper is a contribution to the study of the behavior of activation products produced in irradiated nuclear graphite, graphite being the moderator of the first French generation of CO2 cooled nuclear fission reactors. This paper is focused on the thermal release of Tritium, a major contributor to the initial activity, taking into account the role of the free surfaces (open pores and graphite surface). Two kinds of graphite were compared. On one hand, Highly Oriented Pyrolitic Graphite (HOPG), a model well graphitized graphite, and on the other hand, SLA2, a porous less graphitized nuclear graphite. Deuterium ion implantation at three different energies 70, 200 and 390 keV allows simulating the presence of Tritium at three different depths, corresponding respectively to projected ranges Rp of 0.75, 1.7 and 3.2 μm. The D isotopic tracing is performed thanks to the D(3He,p)4He nuclear reaction. The graphite structure is studied by Raman microspectrometry. Thermal annealing is performed in the temperature range 200-1200 °C up to 300 h annealing time. As observed in a previous study, the results show that the D release occurs according to three kinetic regimes: a rapid permeation through open pores, a transient regime corresponding to detrapping and diffusion of D located at low energy sites correlated to the edges of crystallites and finally a saturation regime attributed to detrapping of interstitial D located at high energy sites inside the crystallites. Below 600 °C, D release is negligible whatever the implantation depth and the graphite type. The present paper clearly puts forward that above 600 °C, the D release decreases at deeper implantation depths and strongly depends on the graphite structure. In HOPG where high energy sites are more abundant, the D release is less dependent on the surface proximity compared to SLA2. In SLA2, in which the low energy sites prevail, the D release curves are clearly shifted towards lower temperatures when D is located

  7. High bandwidth linear viscoelastic properties of complex fluids from the measurement of their free surface fluctuations

    NASA Astrophysics Data System (ADS)

    Pottier, Basile; Talini, Laurence; Frétigny, Christian

    2012-02-01

    We present a new optical method to measure the linear viscoelastic properties of materials, ranging from complex fluids to soft solids, within a large frequency range (about 0.1--10^4 Hz). The surface fluctuation specular reflection technique is based on the measurement of the thermal fluctuations of the free surfaces of materials at which a laser beam is specularly reflected. The propagation of the thermal surface waves depends on the surface tension, density, and complex viscoelastic modulus of the material. For known surface tension and density, we show that the frequency dependent elastic and loss moduli can be deduced from the fluctuation spectrum. Using a viscoelastic solid (a cross-linked PDMS), which linear viscoelastic properties are known in a large frequency range from rheometric measurements and the time--temperature superposition principle, we show that there is a good agreement between the rheological characterization provided by rheometric and fluctuation measurements. We also present measurements conducted with complex fluids that are supramolecular polymer solutions. The agreement with other low frequency and high frequency rheological measurements is again very good, and we discuss the sensitivity of the technique to surface viscoelasticity.

  8. Tuning the Electron Gas at an Oxide Heterointerface via Free Surface Charges

    SciTech Connect

    Bell, Christopher

    2011-08-11

    Oxide heterointerfaces are emerging as one of the most exciting materials systems in condensed matter science. One remarkable example is the LaAlO{sub 3}/SrTiO{sub 3} (LAO/STO) interface, a model system in which a highly mobile electron gas forms between two band insulators, exhibiting two dimensional superconductivity and unusual magnetotransport properties. An ideal tool to tune such an electron gas is the electrostatic field effect. In principle, the electrostatic field can be generated by bound charges due to polarization (as in the normal and ferroelectric field effects) or by adding excess free charge. In previous studies, a large modulation of the carrier density and mobility of the LAO/STO interface has been achieved using the normal field effect. However, little attention has been paid to the field effect generated by free charges. This issue is scarcely addressed, even in conventional semiconductor devices, since the free charges are typically not stable. Here, we demonstrate an unambiguous tuning of the LAO/STO interface conductivity via free surface charges written using conducting atomic force microscopy (AFM). The modulation of the carrier density was found to be reversible, nonvolatile and surprisingly large, {approx}3 x 10{sup 13} cm{sup -2}, comparable to the maximum modulation by the normal field effect. Our finding reveal the efficiency of free charges in controlling the conductivity of this oxide interface, and suggest that this technique may be extended more generally to other oxide systems.

  9. An analytical and numerical study of the nonlinear reflection at a stress-free surface

    SciTech Connect

    Romer, Anne Kim, Jin-Yeon; Jacobs, Laurence J.

    2015-03-31

    Implementation of the ultrasonic second harmonic generation has typically been restricted to simple setups such as through-transmission or Rayleigh surface waves. Recent research has evaluated the second harmonic waves generation in P- and SV- waves reflected from a stress-free surface to enable the single-sided interrogation of a specimen. This research considers the second harmonic generation in an aluminum specimen, which is analytically evaluated using an approach based on a perturbation method. Here, the model is chosen to mimic an experimental setup where the longitudinal wave is generated at oblique angle using a wedge transducer. Due to the mode conversion at the interface of the wedge and the specimen, it is necessary to evaluate longitudinal and shear waves, determining all second harmonic waves generated in the bulk and at the stress-free boundary. The theoretically developed model is then implemented in a commercial finite element code, COMSOL, using increasing fundamental wave amplitudes for different values of third order elastic constants. The results of this computational model verify the analytical approach and the proposed measurement setup, taking into account assumptions and approximations of the solution procedure. Furthermore, the computational model is used to draw important conclusions relevant to the experimental setup, including the need to avoid interaction with diffracted waves.

  10. Thermoelectric magnetohydrodynamic (TEMHD) stirring of liquid lithium

    NASA Astrophysics Data System (ADS)

    Jaworski, M. A.; Xu, Wenyu; Kim, Jason; Lee, Matt; Neumann, Martin; Surla, Vijay; Ruzic, David

    2009-11-01

    The Solid/Liquid Lithium Divertor Experiment (SLiDE) was constructed to examine passive flows in liquid lithium under an applied heat load and external magnetic field. The offered explanation for the results of the CDX-U experiment, where liquid lithium was capable of transporting >50[MW/m^2] of incident heat flux without rapid evaporation, was thermocapillary (Marangonic) driven flows. The SLiDE apparatus utilizes a line-stripe heat source and external magnetic fields to mimic a divertor scenario to test the thermocapillary hypothesis. Instead of thermocapillary induced flows, TEMHD flows are observed on the order of 10 [cm/s]. The thermoelectric effect was confirmed through a series of qualitative experiments in the apparatus which will be described. A quantitative scaling matching the measured target temperatures and heat fluxes is compared to the measured velocities. A novel plasma facing component based on porous material TEMHD is also presented.

  11. Experimental assessment of blade tip immersion depth from free surface on average power and thrust coefficients of marine current turbine

    NASA Astrophysics Data System (ADS)

    Lust, Ethan; Flack, Karen; Luznik, Luksa

    2014-11-01

    Results from an experimental study on the effects of marine current turbine immersion depth from the free surface are presented. Measurements are performed with a 1/25 scale (diameter D = 0.8m) two bladed horizontal axis turbine towed in the large towing tank at the U.S. Naval Academy. Thrust and torque are measured using a dynamometer, mounted in line with the turbine shaft. Shaft rotation speed and blade position are measured using a shaft position indexing system. The tip speed ratio (TSR) is adjusted using a hysteresis brake which is attached to the output shaft. Two optical wave height sensors are used to measure the free surface elevation. The turbine is towed at 1.68 m/s, resulting in a 70% chord based Rec = 4 × 105. An Acoustic Doppler Velocimeter (ADV) is installed one turbine diameter upstream of the turbine rotation plane to characterize the inflow turbulence. Measurements are obtained at four relative blade tip immersion depths of z/D = 0.5, 0.4, 0.3, and 0.2 at a TSR value of 7 to identify the depth where free surface effects impact overall turbine performance. The overall average power and thrust coefficient are presented and compared to previously conducted baseline tests. The influence of wake expansion blockage on the turbine performance due to presence of the free surface at these immersion depths will also be discussed.

  12. Stabilization of tokamak plasma by lithium streams

    SciTech Connect

    L.E. Zakharov

    2000-08-07

    The stabilization theory of free-boundary magnetohydrodynamic instabilities in tokamaks by liquid lithium streams driven by magnetic propulsion is formulated. While the conventional, wall-locked, resistive wall mode can be well suppressed by the flow, a new, stream-locked mode determines the limits of the flow stabilization.

  13. Critical Velocities in Open Capillary Flow

    NASA Technical Reports Server (NTRS)

    Dreyer, Michael; Langbein, Dieter; Rath, Hans J.

    1996-01-01

    This paper describes the proposed research program on open capillary flow and the preliminary work performed theoretically and in drop tower experiments. The work focuses on the fundamental physical understanding of the flow through capillary bound geometries, where the circumference of the cross section of the flow path contains free surfaces. Examples for such a flow configuration are capillary vanes in surface tension tanks, flow along edges and corners and flow through liquid bridges. The geometries may be classified by their cross section areas, wetted circumferences and the radii of curvature of the free surfaces. In the streaming float zone the flow path is bound by a free surface only. The ribbon vane is a model for vane types used in surface tension tanks, where a structure in proximity to the tank wall forms a capillary gap. A groove is used in heat pipes for the transportation of the condensed working fluid to the heat source and a wedge may occur in a spaceborne experiment where fluid has to be transported by the means of surface tension. The research objectives are the determination of the maximum volume flux, the observation of the free surfaces and the liquid flow inside the flow path as well as the evaluation of the limiting capillary wave speed. The restriction of the maximum volume flux is due to convective forces (flow velocity exceeding the capillary wave speed) and/or viscous forces, i.e. the viscous head loss along the flow path must be compensated by the capillary pressure due to the curved free surface. Exceeding the maximum volume flux leads to the choking of the flow path, thus the free surface collapses and.gas ingestion occurs at the outlet. The means are ground-based experimental work with plateau tanks and in a drop tower, a sounding rocket flight, and theoretical analysis with integral balances as well as full three dimensional CFD solutions for flow with free surfaces.

  14. Lithium and strontium isotopic systematics in playas in Nevada, USA: constraints on the origin of lithium

    NASA Astrophysics Data System (ADS)

    Araoka, Daisuke; Kawahata, Hodaka; Takagi, Tetsuichi; Watanabe, Yasushi; Nishimura, Koshi; Nishio, Yoshiro

    2014-03-01

    Lithium-rich brine in playas is a major raw material for lithium production. Recently, lithium isotopic ratios (δ7Li) have been identified as a tool for investigating water-rock interactions. Thus, to constrain the origin of lithium in playas by the use of its isotopes, we conducted leaching experiments on various lacustrine sediment and evaporite deposit samples collected from playas in Nevada, USA. We determined lithium and strontium isotopic ratios and contents and trace element contents of the leachate, estimated the initial δ7Li values in the water flowing into the playas, and examined the origin of lithium in playas by comparison with δ7Li values of the possible sources. In samples from the playas, δ7Li values show some variation, reflecting differences both in isotopic fractionation during mineral formation and in initial δ7Li value in water flowing into each playa. However, all δ7Li values in this study are much lower than those in river water and groundwater samples from around the world, but they are close to those of volcanic rocks. Considering the temperature dependence of lithium isotopic fractionation between solid and fluid, these results indicate that the lithium concentrated in playas in Nevada was supplied mainly through high-temperature water-rock interaction associated with local hydrothermal activity and not directly by low-temperature weathering of surface materials. This study, which is the first to report lithium isotopic compositions in playas, demonstrates that δ7Li may be a useful tracer for determining the origin of lithium and evaluating its accumulation processes in playas.

  15. Molten salt lithium cells

    DOEpatents

    Raistrick, Ian D.; Poris, Jaime; Huggins, Robert A.

    1983-01-01

    Lithium-based cells are promising for applications such as electric vehicles and load-leveling for power plants since lithium is very electropositive and light weight. One type of lithium-based cell utilizes a molten salt electrolyte and is operated in the temperature range of about 400.degree.-500.degree. C. Such high temperature operation accelerates corrosion problems and a substantial amount of energy is lost through heat transfer. The present invention provides an electrochemical cell (10) which may be operated at temperatures between about 100.degree.-170.degree. C. Cell (10) comprises an electrolyte (16), which preferably includes lithium nitrate, and a lithium or lithium alloy electrode (12).

  16. Molten salt lithium cells

    DOEpatents

    Raistrick, I.D.; Poris, J.; Huggins, R.A.

    1980-07-18

    Lithium-based cells are promising for applications such as electric vehicles and load-leveling for power plants since lithium is very electropositive and light weight. One type of lithium-based cell utilizes a molten salt electrolyte and is operated in the temperature range of about 400 to 500/sup 0/C. Such high temperature operation accelerates corrosion problems and a substantial amount of energy is lost through heat transfer. The present invention provides an electrochemical cell which may be operated at temperatures between about 100 to 170/sup 0/C. The cell is comprised of an electrolyte, which preferably includes lithium nitrate, and a lithium or lithium alloy electrode.

  17. Molten salt lithium cells

    DOEpatents

    Raistrick, Ian D.; Poris, Jaime; Huggins, Robert A.

    1982-02-09

    Lithium-based cells are promising for applications such as electric vehicles and load-leveling for power plants since lithium is very electropositive and light weight. One type of lithium-based cell utilizes a molten salt electrolyte and is operated in the temperature range of about 400.degree.-500.degree. C. Such high temperature operation accelerates corrosion problems and a substantial amount of energy is lost through heat transfer. The present invention provides an electrochemical cell (10) which may be operated at temperatures between about 100.degree.-170.degree. C. Cell (10) comprises an electrolyte (16), which preferably includes lithium nitrate, and a lithium or lithium alloy electrode (12).

  18. Lithium Circuit Test Section Design and Fabrication

    SciTech Connect

    Godfroy, Thomas; Garber, Anne; Martin, James

    2006-01-20

    The Early Flight Fission -- Test Facilities (EFF-TF) team has designed and built an actively pumped lithium flow circuit. Modifications were made to a circuit originally designed for NaK to enable the use of lithium that included application specific instrumentation and hardware. Component scale freeze/thaw tests were conducted to both gain experience with handling and behavior of lithium in solid and liquid form and to supply anchor data for a Generalized Fluid System Simulation Program (GFSSP) model that was modified to include the physics for freeze/thaw transitions. Void formation was investigated. The basic circuit components include: reactor segment, lithium to gas heat exchanger, electromagnetic (EM) liquid metal pump, load/drain reservoir, expansion reservoir, instrumentation, and trace heaters. This paper discusses the overall system design and build and the component testing findings.

  19. Lithium Circuit Test Section Design and Fabrication

    NASA Technical Reports Server (NTRS)

    Godfroy, Thomas; Garber, Anne

    2006-01-01

    The Early Flight Fission - Test Facilities (EFF-TF) team has designed and built an actively pumped lithium flow circuit. Modifications were made to a circuit originally designed for NaK to enable the use of lithium that included application specific instrumentation and hardware. Component scale freeze/thaw tests were conducted to both gain experience with handling and behavior of lithium in solid and liquid form and to supply anchor data for a Generalized Fluid System Simulation Program (GFSSP) model that was modified to include the physics for freeze/thaw transitions. Void formation was investigated. The basic circuit components include: reactor segment, lithium to gas heat exchanger, electromagnetic (EM) liquid metal pump, load/drain reservoir, expansion reservoir, instrumentation, and trace heaters. This paper will discuss the overall system design and build and the component testing findings.

  20. Lithium Circuit Test Section Design and Fabrication

    NASA Astrophysics Data System (ADS)

    Godfroy, Thomas; Garber, Anne; Martin, James

    2006-01-01

    The Early Flight Fission - Test Facilities (EFF-TF) team has designed and built an actively pumped lithium flow circuit. Modifications were made to a circuit originally designed for NaK to enable the use of lithium that included application specific instrumentation and hardware. Component scale freeze/thaw tests were conducted to both gain experience with handling and behavior of lithium in solid and liquid form and to supply anchor data for a Generalized Fluid System Simulation Program (GFSSP) model that was modified to include the physics for freeze/thaw transitions. Void formation was investigated. The basic circuit components include: reactor segment, lithium to gas heat exchanger, electromagnetic (EM) liquid metal pump, load/drain reservoir, expansion reservoir, instrumentation, and trace heaters. This paper discusses the overall system design and build and the component testing findings.

  1. Large-n approach to thermodynamic Casimir effects in slabs with free surfaces

    NASA Astrophysics Data System (ADS)

    Diehl, H. W.; Grüneberg, Daniel; Hasenbusch, Martin; Hucht, Alfred; Rutkevich, Sergei B.; Schmidt, Felix M.

    2014-06-01

    The classical n-vector ϕ4 model with O (n) symmetrical Hamiltonian H is considered in a ∞2×L slab geometry bounded by a pair of parallel free surface planes at separation L. Standard quadratic boundary terms implying Robin boundary conditions are included in H. The temperature-dependent scaling functions of the excess free energy and the thermodynamic Casimir force are computed in the large-n limit for temperatures T at, above, and below the bulk critical temperature Tc. Their n =∞ limits can be expressed exactly in terms of the spectrum and eigenfunctions of a self-consistent one-dimensional Schrödinger equation. This equation is solved by numerical means for two distinct discretized versions of the model: in the first ("model A"), only the coordinate z across the slab is discretized and the integrations over momenta conjugate to the lateral coordinates are regularized dimensionally; in the second ("model B"), a simple cubic lattice with periodic boundary conditions along the lateral directions is used. Renormalization-group ideas are invoked to show that, in addition to corrections to scaling ∝L-1, anomalous ones ∝L-1lnL should occur. They can be considerably decreased by taking an appropriate g →∞ (Tc→∞) limit of the ϕ4 interaction constant g. Depending on the model A or B, they can be absorbed completely or to a large extent in an effective thickness Leff=L+δL. Excellent data collapses and consistent high-precision results for both models are obtained. The approach to the low-temperature Goldstone values of the scaling functions is shown to involve logarithmic anomalies. The scaling functions exhibit all qualitative features seen in experiments on the thinning of wetting layers of 4He and Monte Carlo simulations of XY models, including a pronounced minimum of the Casimir force below Tc. The results are in conformity with various analytically known exact properties of the scaling functions.

  2. Free Surface Command Layer for Photoswitchable Out-of-Plane Alignment Control in Liquid Crystalline Polymer Films.

    PubMed

    Nakai, Takashi; Tanaka, Daisuke; Hara, Mitsuo; Nagano, Shusaku; Seki, Takahiro

    2016-01-26

    To date, reversible alignment controls of liquid crystalline materials have widely been achieved by photoreactive layers on solid substrates. In contrast, this work demonstrates the reversible out-of-plane photocontrols of liquid crystalline polymer films by using a photoresponsive skin layer existing at the free surface. A polymethacrylate containing a cyanobiphenyl side-chain mesogen adopts the planar orientation. Upon blending a small amount of azobenzene-containing side-chain polymer followed by successive annealing, segregation of the azobenzene polymer at the free surface occurs and induces a planar to homeotropic orientation transition of cyanobiphenyl mesogens underneath. By irradiation with UV light, the mesogen orientation turns into the planar orientation. The orientation reverts to the homeotropic state upon visible light irradiation or thermally, and such cyclic processes can be repeated many times. On the basis of this principle, erasable optical patterning is performed by irradiating UV light through a photomask. PMID:26734930

  3. X-ray Photon Correlation Spectroscopy Study on Dynamics of the Free Surface in Entangled Polystyrene Melt Films

    NASA Astrophysics Data System (ADS)

    Koga, Tadanori; Li, Chunhua; Endoh, Maya K.; Narayanan, Suresh; Lurio, Laurence; Sinha, Sunil K.

    2011-01-01

    The dynamics of polymer chains near the surface of a melt and within thin films remains a subject of inquiry along with the nature of the glass transition in these systems. Recent studies show that the properties of the free surface region are crucial in determining the anomalous glass transition temperature (Tg) reduction of polymer thin films. In this study, by embedding "dilute" gold nanoparticles in polystyrene (PS) thin films as "markers", we could successfully probe the diffusive Brownian motion which tracks the local viscosity both at the free surface and within the rest of the single PS thin film far above bulk Tg. The technique used was X-ray photon correlation spectroscopy with resonance-enhanced X-rays that allows us to independently measure the motion in the regions of interest at the nanometer scale. We found the presence of the surface reduced viscosity layer in entangled PS thin films at T>>Tg.

  4. Sub-micrometer precision of optical imaging to locate the free surface of a micrometer fluid shape.

    PubMed

    Montanero, J M; Vega, E J; Ferrera, C

    2009-11-01

    In this note, we explore the precision of the optical imaging method for measuring the free surface position of a micrometer fluid shape. For this purpose, images of a liquid film deposited on a rod were acquired and processed. The resulting contour was compared with the corresponding solution to the Young-Laplace equation. The average deviation was about 30nm, 25 times smaller than the pixel size, reflecting the validity of optical imaging for most applications in microfluidics. PMID:19683246

  5. Modeling of Oblique Penetration into Geologic Targets Using Cavity Expansion Penetrator Loading with Target free-Surface Effects

    SciTech Connect

    Jung, Joe; Longcope, Donald B.; Tabbara, Mazen R.

    1999-05-03

    A procedure has been developed to represent the loading on a penetrator and its motion during oblique penetration into geologic media. The penetrator is modeled with the explicit dynamics, finite element computer program PRONTO 3D and the coupled pressure on the penetrator is given in a new loading option based on a separate cavity expansion (CE) solution that accounts for the pressure-reduction from a nearby target free surface. The free-surface influ- ence distance is selected in a predictive manner by considering the pressure to expand a spherical cavity in a finite radius sphere of the target material. The CE/PRONTO 3D procedure allows a detailed description of the penetrator for predicting shock environments or structural failure dur- ing the entire penetration event and is sufficiently rapid to be used in design optimization. It has been evaluated by comparing its results with data from two field tests of a full-scale penetrator into frozen soil at an impact angles of 49.6 and 52.5 degrees from the horizontal. The measured penetrator rotations were 24 and 22 degrees, respectively. In the simulation, the rotation was21 degrees and predominately resulted from the pressure reduction of the free surface. Good agree- ment was also found for the penetration depth and axial and lateral acceleration at two locations in the penetrator.

  6. Surfactant effects on cumulative drop size distributions produced by air bubbles bursting on a non-quiescent free surface

    NASA Astrophysics Data System (ADS)

    Parmar, K.; Liu, X.; Duncan, J. H.

    2013-11-01

    The generation of droplets when air bubbles travel upwards from within a liquid and burst at a free surface is studied experimentally. The bubbles are generated in a glass water tank that is 0.91 m long and 0.46 m wide with a water depth of 0.5 m. The tank is equipped with an acrylic box at its bottom that creates the bubble field using filtered air injected through an array of 180 hypodermic needles (0.33 mm ID). Two different surface conditions are created by using clean water and a 0.4% aqueous solution of Triton X-100 surfactant. Measurements of the bubble diameters as they approach the free surface are obtained with diffuse light shadowgraph images. The range of bubble diameters studied is 2.885 mm to 3.301 mm for clean water and 2.369 mm to 3.014 mm for the surfactant solution. A laser-light high-speed cinematic shadowgraph system is employed to record and measure the diameters and motions of the droplets at the free surface. This system can measure droplets with diameters <= 50 μm. The results show a clear distinction between the droplet distributions obtained in clean water and the surfactant solution. A bimodal droplet distribution is observed for clean water with at least two dominating peaks. For the surfactant solution, a single distribution peak is seen. This work is supported by the National Science Foundation, Division of Ocean Sciences.

  7. Lithium use in batteries

    USGS Publications Warehouse

    Goonan, Thomas G.

    2012-01-01

    Lithium has a number of uses but one of the most valuable is as a component of high energy-density rechargeable lithium-ion batteries. Because of concerns over carbon dioxide footprint and increasing hydrocarbon fuel cost (reduced supply), lithium may become even more important in large batteries for powering all-electric and hybrid vehicles. It would take 1.4 to 3.0 kilograms of lithium equivalent (7.5 to 16.0 kilograms of lithium carbonate) to support a 40-mile trip in an electric vehicle before requiring recharge. This could create a large demand for lithium. Estimates of future lithium demand vary, based on numerous variables. Some of those variables include the potential for recycling, widespread public acceptance of electric vehicles, or the possibility of incentives for converting to lithium-ion-powered engines. Increased electric usage could cause electricity prices to increase. Because of reduced demand, hydrocarbon fuel prices would likely decrease, making hydrocarbon fuel more desirable. In 2009, 13 percent of worldwide lithium reserves, expressed in terms of contained lithium, were reported to be within hard rock mineral deposits, and 87 percent, within brine deposits. Most of the lithium recovered from brine came from Chile, with smaller amounts from China, Argentina, and the United States. Chile also has lithium mineral reserves, as does Australia. Another source of lithium is from recycled batteries. When lithium-ion batteries begin to power vehicles, it is expected that battery recycling rates will increase because vehicle battery recycling systems can be used to produce new lithium-ion batteries.

  8. Parallelizable flood fill algorithm and corrective interface tracking approach applied to the simulation of multiple finite size bubbles merging with a free surface

    NASA Astrophysics Data System (ADS)

    Lafferty, Nathan; Badreddine, Hassan; Niceno, Bojan; Prasser, Horst-Michael

    2015-11-01

    A parallelizable flood fill algorithm is developed for identifying and tracking closed regions of fluids, dispersed phases, in CFD simulations of multiphase flows. It is used in conjunction with a newly developed method, corrective interface tracking, for simulating finite size dispersed bubbly flows in which the bubbles are too small relative to the grid to be simulated accurately with interface tracking techniques and too large relative to the grid for Lagrangian particle tracking techniques. The latter situation arising if local bubble induced turbulence is resolved, or modeled with LES. With corrective interface tracking the governing equations are solved on a static Eulerian grid. A correcting force, derived from empirical correlation based hydrodynamic forces, is applied to the bubble which is then advected using interface tracking techniques. This method results in accurate fluid-gas two-way coupling, bubble shapes, and terminal rise velocities. The flood fill algorithm and corrective interface tracking technique are applied to an air/water simulation of multiple bubbles rising and merging with a free surface. They are then validated against the same simulation performed using only interface tracking with a much finer grid.

  9. The synergetic effect of lithium polysulfide and lithium nitrate to prevent lithium dendrite growth.

    PubMed

    Li, Weiyang; Yao, Hongbin; Yan, Kai; Zheng, Guangyuan; Liang, Zheng; Chiang, Yet-Ming; Cui, Yi

    2015-01-01

    Lithium metal has shown great promise as an anode material for high-energy storage systems, owing to its high theoretical specific capacity and low negative electrochemical potential. Unfortunately, uncontrolled dendritic and mossy lithium growth, as well as electrolyte decomposition inherent in lithium metal-based batteries, cause safety issues and low Coulombic efficiency. Here we demonstrate that the growth of lithium dendrites can be suppressed by exploiting the reaction between lithium and lithium polysulfide, which has long been considered as a critical flaw in lithium-sulfur batteries. We show that a stable and uniform solid electrolyte interphase layer is formed due to a synergetic effect of both lithium polysulfide and lithium nitrate as additives in ether-based electrolyte, preventing dendrite growth and minimizing electrolyte decomposition. Our findings allow for re-evaluation of the reactions regarding lithium polysulfide, lithium nitrate and lithium metal, and provide insights into solving the problems associated with lithium metal anodes. PMID:26081242

  10. The synergetic effect of lithium polysulfide and lithium nitrate to prevent lithium dendrite growth

    NASA Astrophysics Data System (ADS)

    Li, Weiyang; Yao, Hongbin; Yan, Kai; Zheng, Guangyuan; Liang, Zheng; Chiang, Yet-Ming; Cui, Yi

    2015-06-01

    Lithium metal has shown great promise as an anode material for high-energy storage systems, owing to its high theoretical specific capacity and low negative electrochemical potential. Unfortunately, uncontrolled dendritic and mossy lithium growth, as well as electrolyte decomposition inherent in lithium metal-based batteries, cause safety issues and low Coulombic efficiency. Here we demonstrate that the growth of lithium dendrites can be suppressed by exploiting the reaction between lithium and lithium polysulfide, which has long been considered as a critical flaw in lithium-sulfur batteries. We show that a stable and uniform solid electrolyte interphase layer is formed due to a synergetic effect of both lithium polysulfide and lithium nitrate as additives in ether-based electrolyte, preventing dendrite growth and minimizing electrolyte decomposition. Our findings allow for re-evaluation of the reactions regarding lithium polysulfide, lithium nitrate and lithium metal, and provide insights into solving the problems associated with lithium metal anodes.

  11. Method of recycling lithium borate to lithium borohydride through diborane

    DOEpatents

    Filby, Evan E.

    1976-01-01

    This invention provides a method for the recycling of lithium borate to lithium borohydride which can be reacted with water to generate hydrogen for utilization as a fuel. The lithium borate by-product of the hydrogen generation reaction is reacted with hydrogen chloride and water to produce boric acid and lithium chloride. The boric acid and lithium chloride are converted to lithium borohydride through a diborane intermediate to complete the recycle scheme.

  12. Lithium Redistribution in Lithium-Metal Batteries

    SciTech Connect

    Ferrese, A; Albertus, P; Christensen, J; Newman, J

    2012-01-01

    A model of a lithium-metal battery with a CoO2 positive electrode has been modeled in order to predict the movement of lithium in the negative electrode along the negative electrode/separator interface during cell cycling. A finite-element approach was used to incorporate an intercalation positive electrode using superposition, electrode tabbing, transport using concentrated solution theory, as well as the net movement of the lithium electrode during cycling. From this model, it has been found that movement of lithium along the negative electrode/separator interface does occur during cycling and is affected by three factors: the cell geometry, the slope of the open-circuit-potential function of the positive electrode, and concentration gradients in both the solid and liquid phases in the cell. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.027210jes] All rights reserved.

  13. Lithospheric stresses in Rayleigh-Bénard convection: effects of a free surface and a viscoelastic Maxwell rheology

    NASA Astrophysics Data System (ADS)

    Thielmann, M.; Kaus, B. J. P.; Popov, A. A.

    2015-12-01

    Numerical models of mantle convection typically employ a temperature- or pressure-dependent viscous or viscoplastic rheology and a free slip upper boundary condition. The Earth, however, has a stress-free rather than a free slip surface condition. In addition, with decreasing temperature, the viscosity of rocks increases, which might induce a change from viscous to elastic behaviour (depending on the timescale of deformation). Here, we study the effects of both a Maxwell viscoelastic rheology and a free surface upper boundary condition on viscoelastic convection with a strongly temperature dependent rheology. We particularly focus on the effect of elasticity on the stress state of the lithosphere. Results show that convection vigor and heat transport are not significantly altered by the upper boundary condition or by elasticity. However, the stress state of the lithosphere is significantly affected by both factors. If elasticity is unimportant, a free surface upper boundary condition results in significantly elevated surface stresses (which are up to two magnitudes larger than in the free slip case). Elasticity counteracts this effect and significantly reduces the surface stresses, but distributes stresses over a thicker layer than in the case of a purely viscous rheology. At Earth-like conditions, this effect is significant. While it is warranted to use a free slip upper boundary condition and neglecting elasticity when studying mantle convection and its effect on the thermal state of the Earth, both factors are significant when one wants to predict the stress state of the lithosphere and related questions. Additional 2-D simulations of a plume impinging on a constant thickness and constant viscosity lithosphere show that reasonable parameters might induce lithospheric stress levels that are on the order of a GPa or larger, for viscous free surface models, and that these stresses are several orders of magnitude larger than stresses that occur for free slip models

  14. Experimental study of time-dependent flows in laboratory atmospheric flow models

    NASA Technical Reports Server (NTRS)

    Rush, J. E.

    1982-01-01

    Baroclinic waves in a rotating, differentially-heated annulus of liquid were studied in support of the Atmospheric General Circulation Experiment. Specific objectives were to determine: (1) the nature of the flow at shallow depths, (2) the effect of a rigid lid vs. free surface, and (3) the nature of fluctuations in the waves as a function of rotation rate, depth, and type of surface. It is found that flows with a rigid lid are basically the same as those with a free surface, except for a decrease in flow rate. At shallow depths steady flows are found in essentially the same form, but the incidence of unsteady flows is greatly diminished.

  15. Interaction of a strong blast wave with a free surface. [at ocean surface

    NASA Technical Reports Server (NTRS)

    Falade, A.; Holt, M.

    1978-01-01

    When a point source explosion is initiated at the ocean surface, the shock propagated into the water is reflected at the surface as a centered expansion wave. The solution in the neighborhood of the interaction point is obtained by writing the equations of motion in the appropriate similarity variables and then changing the independent variables to polar coordinates based at the interaction point. From the zero-order solution of the resulting equations the slopes of boundaries at the interaction point are obtained. A first-order perturbation of this solution provides more accurate representation of the flow variables and the curvature of the shock surface near the interaction point.

  16. Lithium and symptomatic hyperparathyroidism.

    PubMed Central

    Ananth, J; Dubin, S E

    1983-01-01

    Hyperparathyroidism with or without adenoma has occasionally been reported in association with lithium treatment, and in symptomatic patients depression, psychosis and an exacerbation of existing psychopathology may occur. Three lithium-treated patients with hyperparathyroidism are reported, in whom discontinuation of lithium in one and removal of parathyroid adenomata in two led to both a reduction in plasma calcium levels and an improvement in their psychopathology. PMID:6423822

  17. Lithium purification technique

    DOEpatents

    Keough, R.F.; Meadows, G.E.

    1984-01-10

    A method for purifying liquid lithium to remove unwanted quantities of nitrogen or aluminum. The method involves precipitation of aluminum nitride by adding a reagent to the liquid lithium. The reagent will be either nitrogen or aluminum in a quantity adequate to react with the unwanted quantity of the impurity to form insoluble aluminum nitride. The aluminum nitride can be mechanically separated from the molten liquid lithium.

  18. Lithium purification technique

    DOEpatents

    Keough, Robert F.; Meadows, George E.

    1985-01-01

    A method for purifying liquid lithium to remove unwanted quantities of nitrogen or aluminum. The method involves precipitation of aluminum nitride by adding a reagent to the liquid lithium. The reagent will be either nitrogen or aluminum in a quantity adequate to react with the unwanted quantity of the impurity to form insoluble aluminum nitride. The aluminum nitride can be mechanically separated from the molten liquid lithium.

  19. Free-Surface and Contact Line Motion of Liquid in Microgravity

    NASA Technical Reports Server (NTRS)

    Schwartz, Leonard W.

    1996-01-01

    This project involves fundamental studies of the role of nonlinearity in determining the motion of liquid masses under the principal influences of surface tension, viscosity and inertia. Issues to be explored are relevant to aspects of terrestrial processes, as well as being immediately applicable to fluid management in a low-gravity environment. Specific issues include: (1) the mechanic's of liquid masses in large-amplitude motions, (2) the influence of bounding surfaces on the motion, and (3) the ability of such surfaces to control liquid motion by wetting forces, especially when they are augmented by various surface treatments. Mathematical techniques include asymptotic analysis of the governing equations, for problem simplification, and numerical simulation, using both boundary-element and finite-difference methods. The flow problem is divided into an 'outer' or inviscid potential-flow region and one or more inner, or viscous dominated, regions. Relevant to one inner region, the vicinity of the contact line, we discuss time-dependent simulation of slow droplet motion, on a surface of variable wettability, using the lubrication approximation. The simulation uses a disjoining pressure model and reproduces realistic wetting-dewetting behavior.

  20. Properties of lead-lithium solutions

    SciTech Connect

    Hoffman, N.J.; Darnell, A.; Blink, J.A.

    1980-10-01

    Lead-lithium solutions are of interest to liquid metal wall ICF reactor designers because Pb may be present to some extent in both heavy ion beam and laser-driven ICF targets; therefore, Pb will be present as an impurity in a flowing lithium wall. In addition, Pb-Li solutions containing approx. 80 a/o Pb are a strong candidate for a heavy ion beam driven HYLIFE converter and a viable alternative to a pure Li wall for a laser driven converter. The properties of Pb-Li solutions including the effect of hydrogen impurities are reviewed, and the reactor design implications are discussed.

  1. On using the levelling of the free surface of a Newtonian fluid to measure viscosity and Navier slip length

    PubMed Central

    Gilormini, P.; Teyssèdre, H.

    2013-01-01

    Measuring the relaxation time involved in the levelling of a free surface of a Newtonian fluid laid on a substrate can give access to material parameters. It is shown here how most favourable pattern geometries of the free surface and film thicknesses can be defined for the measures of viscosity and Navier slip length at the fluid–solid interface, respectively. Moreover, we put special emphasis on the conditions required to avoid shear thinning by controlling the maximum shear rate. For initially sinusoidal patterns with infinitesimal amplitudes, an analytical solution including slip at the fluid–solid interface is used, and numerical simulations based on the natural element method allow one to discuss the effect of finite amplitudes. This leads to the definition of a relevance domain for the analytical solution that avoids the need for numerical simulations in practical applications. It is also shown how these results can be applied to crenelated profiles, where Fourier series expansion can be used, but with caution. PMID:24353474

  2. Zero-gravity Mean Free Surface Curvature of a Confined Liquid in a Radially-Vaned Container

    NASA Technical Reports Server (NTRS)

    Chen, Yongkang; Callahan, Michael; Weislogel, Mark

    2013-01-01

    A variety of increasingly intricate container geometries are under consideration for the passive manipulation of liquids aboard spacecraft where the impact of gravity may be neglected. In this study we examine the mean curvature of a liquid volume confined within a radial array of disconnected vanes of infinite extent. This particular geometry possesses a number of desirable characteristics relevant to waste water treatment aboard spacecraft for life support. It is observed that under certain conditions the slender shape of the free surface approaches an asymptote, which can be predicted analytically using new hybrid boundary conditions proposed herein. This contribution represents possibly the final extension of what has been referred to as the method of de Lazzer et al. (1996). The method enables the integration of the Young-Laplace equation over a domain with its boundaries, including the wetted portion of the solid boundaries, symmetry planes, and circular arcs representing free surfaces at the center plane of the liquid body. Asymptotic solutions at several limits are obtained and the analysis is confirmed with numerical computations.

  3. Ammonia decomposition catalysis using lithium-calcium imide.

    PubMed

    Makepeace, Joshua W; Hunter, Hazel M A; Wood, Thomas J; Smith, Ronald I; Murray, Claire A; David, William I F

    2016-07-01

    Lithium-calcium imide is explored as a catalyst for the decomposition of ammonia. It shows the highest ammonia decomposition activity yet reported for a pure light metal amide or imide, comparable to lithium imide-amide at high temperature, with superior conversion observed at lower temperatures. Importantly, the post-reaction mass recovery of lithium-calcium imide is almost complete, indicating that it may be easier to contain than the other amide-imide catalysts reported to date. The basis of this improved recovery is that the catalyst is, at least partially, solid across the temperature range studied under ammonia flow. However, lithium-calcium imide itself is only stable at low and high temperatures under ammonia, with in situ powder diffraction showing the decomposition of the catalyst to lithium amide-imide and calcium imide at intermediate temperatures of 200-460 °C. PMID:27092374

  4. The Bouncing Jet: A Newtonian Liquid Rebounding off a Free Surface

    NASA Astrophysics Data System (ADS)

    Thrasher, Matthew; Jung, Sunghwan; Pang, Yee Kwong; Chuu, Chih-Piao; Swinney, Harry L.

    2007-10-01

    We find that a liquid jet can bounce off a bath of the same liquid if the bath is moving horizontally with respect to the jet. Previous observations of jets rebounding off a bath (e.g. Kaye effect) have been reported only for non-Newtonian fluids, while we observe bouncing jets in a variety of Newtonian fluids, including mineral oil poured by hand. A thin layer of air separates the bouncing jet from the bath, and the relative motion replenishes the film of air. Jets with one or two bounces are stable for a range of viscosity, jet flow rate and velocity, and bath velocity. The bouncing jet phenomenon can be observed in many household fluids using only minimal equipment, making it accessible as a classroom demonstration and a science project.

  5. Apparatus and method for atmospheric pressure reactive atom plasma processing for shaping of damage free surfaces

    DOEpatents

    Carr; Jeffrey W.

    2009-03-31

    Fabrication apparatus and methods are disclosed for shaping and finishing difficult materials with no subsurface damage. The apparatus and methods use an atmospheric pressure mixed gas plasma discharge as a sub-aperture polisher of, for example, fused silica and single crystal silicon, silicon carbide and other materials. In one example, workpiece material is removed at the atomic level through reaction with fluorine atoms. In this example, these reactive species are produced by a noble gas plasma from trace constituent fluorocarbons or other fluorine containing gases added to the host argon matrix. The products of the reaction are gas phase compounds that flow from the surface of the workpiece, exposing fresh material to the etchant without condensation and redeposition on the newly created surface. The discharge provides a stable and predictable distribution of reactive species permitting the generation of a predetermined surface by translating the plasma across the workpiece along a calculated path.

  6. Node-Pore Sensing Enables Label-Free Surface-Marker Profiling of Single Cells

    PubMed Central

    2015-01-01

    Flow cytometry is a ubiquitous, multiparametric method for characterizing cellular populations. However, this method can grow increasingly complex with the number of proteins that need to be screened simultaneously: spectral emission overlap of fluorophores and the subsequent need for compensation, lengthy sample preparation, and multiple control tests that need to be performed separately must all be considered. These factors lead to increased costs, and consequently, flow cytometry is performed in core facilities with a dedicated technician operating the instrument. Here, we describe a low-cost, label-free microfluidic method that can determine the phenotypic profiles of single cells. Our method employs Node-Pore Sensing to measure the transit times of cells as they interact with a series of different antibodies, each corresponding to a specific cell-surface antigen, that have been functionalized in a single microfluidic channel. We demonstrate the capabilities of our method not only by screening two acute promyelocytic leukemia human cells lines (NB4 and AP-1060) for myeloid antigens, CD13, CD14, CD15, and CD33, simultaneously, but also by distinguishing a mixture of cells of similar size—AP-1060 and NALM-1—based on surface markers CD13 and HLA-DR. Furthermore, we show that our method can screen complex subpopulations in clinical samples: we successfully identified the blast population in primary human bone marrow samples from patients with acute myeloid leukemia and screened these cells for CD13, CD34, and HLA-DR. We show that our label-free method is an affordable, highly sensitive, and user-friendly technology that has the potential to transform cellular screening at the benchside. PMID:25625182

  7. Node-pore sensing enables label-free surface-marker profiling of single cells.

    PubMed

    Balakrishnan, Karthik R; Whang, Jeremy C; Hwang, Richard; Hack, James H; Godley, Lucy A; Sohn, Lydia L

    2015-03-01

    Flow cytometry is a ubiquitous, multiparametric method for characterizing cellular populations. However, this method can grow increasingly complex with the number of proteins that need to be screened simultaneously: spectral emission overlap of fluorophores and the subsequent need for compensation, lengthy sample preparation, and multiple control tests that need to be performed separately must all be considered. These factors lead to increased costs, and consequently, flow cytometry is performed in core facilities with a dedicated technician operating the instrument. Here, we describe a low-cost, label-free microfluidic method that can determine the phenotypic profiles of single cells. Our method employs Node-Pore Sensing to measure the transit times of cells as they interact with a series of different antibodies, each corresponding to a specific cell-surface antigen, that have been functionalized in a single microfluidic channel. We demonstrate the capabilities of our method not only by screening two acute promyelocytic leukemia human cells lines (NB4 and AP-1060) for myeloid antigens, CD13, CD14, CD15, and CD33, simultaneously, but also by distinguishing a mixture of cells of similar size—AP-1060 and NALM-1—based on surface markers CD13 and HLA-DR. Furthermore, we show that our method can screen complex subpopulations in clinical samples: we successfully identified the blast population in primary human bone marrow samples from patients with acute myeloid leukemia and screened these cells for CD13, CD34, and HLA-DR. We show that our label-free method is an affordable, highly sensitive, and user-friendly technology that has the potential to transform cellular screening at the benchside. PMID:25625182

  8. An angular fluidic channel for prism-free surface-plasmon-assisted fluorescence capturing

    NASA Astrophysics Data System (ADS)

    Nomura, Ken-Ichi; Gopinath, Subash C. B.; Lakshmipriya, Thangavel; Fukuda, Nobuko; Wang, Xiaomin; Fujimaki, Makoto

    2013-12-01

    Surface plasmon excitation provides stronger enhancement of the fluorescence intensity and better sensitivity than other sensing approaches but requires optimal positioning of a prism to ensure optimum output of the incident light. Here we describe a simple, highly sensitive optical sensing system combining surface plasmon excitation and fluorescence to address this limitation. V-shaped fluidic channels are employed to mimic the functions of a prism, sensing plate, and flow channel in a single setup. Superior performance is demonstrated for different biomolecular recognition reactions on a self-assembled monolayer, and the sensitivity reaches 100 fM for biotin-streptavidin interactions. Using an antibody as a probe, we demonstrate the detection of intact influenza viruses at 0.2 HA units ml-1 levels. The convenient sensing system developed here has the advantages of being prism-free and requiring less sample (1-2 μl), making this platform suitable for use in situations requiring low sample volumes.

  9. Laminar Multicell Lithium Batteries

    SciTech Connect

    Bruder, A. H.

    1984-01-31

    Laminar batteries of series connected cells comprising lithium anodes and an electrolyte containing a passivating solvent reactive with lithium in which the cells are electrically connected in series by intercell barriers comprising outer layers of electrochemically inert electronically conducting material in contact with the electrochemically active anode and cathode of adjacent cells and a layer of metal foil between the electrochemically inert layers.

  10. Cathode material for lithium batteries

    DOEpatents

    Park, Sang-Ho; Amine, Khalil

    2015-01-13

    A method of manufacture an article of a cathode (positive electrode) material for lithium batteries. The cathode material is a lithium molybdenum composite transition metal oxide material and is prepared by mixing in a solid state an intermediate molybdenum composite transition metal oxide and a lithium source. The mixture is thermally treated to obtain the lithium molybdenum composite transition metal oxide cathode material.

  11. Cathode material for lithium batteries

    DOEpatents

    Park, Sang-Ho; Amine, Khalil

    2013-07-23

    A method of manufacture an article of a cathode (positive electrode) material for lithium batteries. The cathode material is a lithium molybdenum composite transition metal oxide material and is prepared by mixing in a solid state an intermediate molybdenum composite transition metal oxide and a lithium source. The mixture is thermally treated to obtain the lithium molybdenum composite transition metal oxide cathode material.

  12. Lithium and autophagy.

    PubMed

    Motoi, Yumiko; Shimada, Kohei; Ishiguro, Koichi; Hattori, Nobutaka

    2014-06-18

    Lithium, a drug used to treat bipolar disorders, has a variety of neuroprotective mechanisms, including autophagy regulation, in various neuropsychiatric conditions. In neurodegenerative diseases, lithium enhances degradation of aggregate-prone proteins, including mutated huntingtin, phosphorylated tau, and α-synuclein, and causes damaged mitochondria to degrade, while in a mouse model of cerebral ischemia and Alzheimer's disease autophagy downregulation by lithium is observed. The signaling pathway of lithium as an autophagy enhancer might be associated with the mammalian target of rapamycin (mTOR)-independent pathway, which is involved in myo-inositol-1,4,5-trisphosphate (IP3) in Huntington's disease and Parkinson's disease. However, the mTOR-dependent pathway might be involved in inhibiting glycogen synthase kinase-3β (GSK3β) in other diseases. Lithium's autophagy-enhancing property may contribute to the therapeutic benefit of patients with neuropsychiatric disorders. PMID:24738557

  13. 4D photogrammetric technique to study free surface water in open channels

    NASA Astrophysics Data System (ADS)

    Aubé, Damien; Berkaoui, Amine; Vinatier, Fabrice; Bailly, Jean-Stéphane; Belaud, Gilles

    2015-04-01

    Characteristics of three-dimensional surface water are considered as the most valuable information to understand hydrodynamic phenomena in open channel flow. An accurate and coherent description of the free water surface morphology improves the accuracy of hydraulic models which study river processes. However, amongst existing techniques to measure three-dimensional surface, stereo-photogrammetry is clearly the most effective technique to obtain an instantaneous and high accurate 3D free water surface and it's suitable to both flume and field condition. Our study aims at developing this technique in two controlled channels, one in interior with glass borders (length: 6 m, width: 0.3 m and depth: 0.5 m) and one outside with cement borders (length: 13 m, width: 0.7 m and depth: 0.4 m). A system consisting in three NIKON-D3200 cameras, mounted to an adjustable tripod head, which is fixed to an inverted aluminium T-bar with the center camera higher than the two side cameras. Each camera is fitted with a 28 mm lens and cameras are synchronized using a Phottix(R) system. The system was mounted at a downstream position from the channel with an oblique configuration. A series of pictures taken at a 3 s interval during the water weight bearing were reported and analyzed using the Photoscan Pro(R) software for image matching. Validation procedure of the technique was realized using an orthophotography of the lateral border of the interior channel to delimit the line of water surface, and using a video capture of a slide fixed inside the outside channel. A high resolution and dynamic elevation map of the surface water was constructed. Our study give encouraging results, with a good capture of water surface morphology and a limited occlusion issues. The confrontation of the results with the validation dataset highlight limitations that need to be discussed with the audience.

  14. Lithium metal oxide electrodes for lithium batteries

    DOEpatents

    Thackeray, Michael M.; Kim, Jeom-Soo; Johnson, Christopher S.

    2008-01-01

    An uncycled electrode for a non-aqueous lithium electrochemical cell including a lithium metal oxide having the formula Li.sub.(2+2x)/(2+x)M'.sub.2x/(2+x)M.sub.(2-2x)/(2+x)O.sub.2-.delta., in which 0.ltoreq.x<1 and .delta. is less than 0.2, and in which M is a non-lithium metal ion with an average trivalent oxidation state selected from two or more of the first row transition metals or lighter metal elements in the periodic table, and M' is one or more ions with an average tetravalent oxidation state selected from the first and second row transition metal elements and Sn. Methods of preconditioning the electrodes are disclosed as are electrochemical cells and batteries containing the electrodes.

  15. Free-Surface Optical Scattering as an Indicator of the Shock-Induced Solid-Liquid Phase Transition in Tin

    SciTech Connect

    Stevens, G. D.; Lutz, S. S.; Marshall, B. R.; Turley, W. D.; Veeser, L. R.; Furlanetto, M. R.; Hixson, R. S.; Holtkamp, D. B.; Jensen, B. J.; Rigg, P. A.; Wilke, M. D.

    2008-07-01

    When highly polished metal surfaces melt upon release after shock loading, they exhibit features that suggest significant surface changes accompany the phase transition. The reflection of light from such surfaces changes from specular (pre-shock) to diffuse upon melting. A familiar manifestation of this phenomenon is the loss of signal light in VISAR measurements, which occurs at pressures high enough to melt the free surface. Unlike many other potential material phase-sensitive diagnostics (e.g., reflectometry, conductivity) that show relatively small (1%–10%) changes, the specularity of reflection provides a more sensitive and definitive indication of the solid-liquid phase transition. Data will be presented that support the hypothesis that specularity changes indicate melt in a way that can be measured easily and unambiguously.

  16. Interaction of small mobile stacking fault tetrahedra with free surfaces, dislocations, and interfaces in Cu and Cu-Nb

    NASA Astrophysics Data System (ADS)

    Martínez, Enrique; Uberuaga, Blas P.; Beyerlein, Irene J.

    2016-02-01

    The presence of stacking fault tetrahedra (SFTs) in face-centered-cubic metals substantially modifies the material response to external loading. These defects are extremely stable with increasing energetic stability as they grow in size. At the sizes visible within a transmission electron microscope, they appear nearly immobile. We have recently shown that these defects might indeed migrate, with defective SFTs exhibiting particularly high mobilities. In this paper, using molecular dynamics, we show how mobile SFTs interact with various types of extended defects, including free surfaces, dislocations, and interfaces in Cu and Cu-Nb systems. We observe a direct relation between the energetics of a single vacancy interacting with each external defect and the propensity for the SFT to be absorbed. Finally, using mesoscale modeling, we show how the fact that SFTs can migrate influences the system evolution and potentially important observables of interest such as the void denuded zones around defect sinks.

  17. Effect of free surface roughness on the apparent glass transition temperature in thin polymer films measured by ellipsometry.

    PubMed

    Efremov, Mikhail Yu

    2014-12-01

    Ellipsometry is one of the standard methods for observation of glass transition in thin polymer films. This work proposes that sensitivity of the method to surface morphology can complicate manifestation of the transition in a few nm thick samples. Two possible mechanisms of free surface roughening in the vicinity of glass transition are discussed: roughening due to lateral heterogeneity and roughening associated with thermal capillary waves. Both mechanisms imply an onset of surface roughness in the glass transition temperature range, which affects the experimental data in a way that shifts apparent glass transition temperature. Effective medium approximation models are used to introduce surface roughness into optical calculations. The results of the optical modeling for a 5 nm thick polystyrene film on silicon are presented. PMID:25554303

  18. Verification and transfer of thermal pollution model. Volume 2: User's manual for 3-dimensional free-surface model

    NASA Technical Reports Server (NTRS)

    Lee, S. S.; Sengupta, S.; Tuann, S. Y.; Lee, C. R.

    1982-01-01

    The six-volume report: describes the theory of a three-dimensional (3-D) mathematical thermal discharge model and a related one-dimensional (1-D) model, includes model verification at two sites, and provides a separate user's manual for each model. The 3-D model has two forms: free surface and rigid lid. The former, verified at Anclote Anchorage (FL), allows a free air/water interface and is suited for significant surface wave heights compared to mean water depth; e.g., estuaries and coastal regions. The latter, verified at Lake Keowee (SC), is suited for small surface wave heights compared to depth. These models allow computation of time-dependent velocity and temperature fields for given initial conditions and time-varying boundary conditions.

  19. Growth of GaAs from a free surface melt under controlled arsenic pressure in a partially confined configuration

    NASA Technical Reports Server (NTRS)

    Gatos, H. C.; Lagowski, J.; Wu, Y.

    1988-01-01

    A partially confined configuration for the growth of GaAs from melt in space was developed, consisting of a triangular prism containing the seed crystal and source material in the form of a rod. It is suggested that the configuration overcomes two obstacles in the growth of GaAs in space: total confinement in a quartz crucible and lack of arsenic pressure control. Ground tests of the configuration show that it is capable of crystal growth in space and is useful for studying the growth of GaAs from a free-surface melt on earth. The resulting chemical composition, electrical property variations, and phenomenological models to account for the results are presented.

  20. Slip at the surface of a translating-rotating sphere bisected by a free surface bounding a semi-infinite viscous fluid: Removal of the contact-line singularity

    NASA Astrophysics Data System (ADS)

    O'Neill, M. E.; Ranger, K. B.; Brenner, H.

    1986-04-01

    A linear slip, Basset-type, boundary condition having an experimentally adjustable phenomenological slip coefficient is used to remove the contact-line singularity that would otherwise prevent the movement of a partially penetrating sphere normal to a planar free surface F bounding a semi-infinite viscous fluid. Stokes flow calculations are presented for the quasistatic hydrodynamic force and torque resistance matrix for a half-submerged sphere that is instantaneously translating and rotating with vector velocities that are arbitrarily oriented relative to the free-surface unit normal vector. The singular components of this material matrix (arising either during translational motion normal to F or rotational motion about an axis lying within F) are shown to be finite for finite slip coefficients β, and to become logarithmically infinite in the traditional nonslip limit β→∞. The relative weakness of this logarithmic singularity suggests that a degree of slip as small as, say, 0.01%—which would presumably be kinematically indistinguishable from the no-slip case—could easily masquerade as a conventional ``wall effect'' on the Stokes drag. A small degree of slip is thus hypothesized as a mechanism that would permit the observed transport of Brownian corpuscles across interfacial regions.

  1. Flow rate limitation in open capillary channel flows.

    PubMed

    Haake, Dennis; Rosendahl, Uwe; Ohlhoff, Antje; Dreyer, Michael E

    2006-09-01

    This paper reports the experimental and theoretical investigations of forced liquid flows through open capillary channels under reduced gravity conditions. An open capillary channel is a structure that establishes a liquid flow path at low Bond numbers, when the capillary pressure caused by the surface tension force dominates in comparison to the hydrostatic pressure induced by gravitational or residual accelerations. In case of steady flow through the channel, the capillary pressure of the free surface balances the pressure difference between the liquid and the surrounding constant-pressure gas phase. Because of convective and viscous momentum transport, the pressure along the flow path decreases and causes the free surface to bend inward. The maximum flow rate is achieved when the free surface collapses and gas ingestion occurs at the outlet. This critical flow rate depends on the geometry of the channel and the properties of the liquid. In this paper we present a comparison of the theoretical and experimental critical flow rates and surface profiles for convective dominated flows. For the prediction of the critical flow rate a one-dimensional theoretical model taking into account the entrance pressure loss and the frictional pressure loss in the channel is developed. PMID:17124140

  2. Lithium cell test results

    NASA Technical Reports Server (NTRS)

    Bragg, B. J.

    1977-01-01

    Three lithium SO2 cells, two lithium CF cells, and a vinyl chloride cell, all with crimped seals, and all strictly experimental, were independently discharged on resistors. Three temperatures were used and several different storage temperatures. Discharge rate generally on the nominal discharges were 0.1 amp, 0.5 amp, and 1 amp. Tests results show that the crimp seals are inadequate, especially for the SO2 cells. Normal discharges present no hazards. All cells discharge to zero. The problem of lithium cell explosions, such as occurred during off-limits testing, is discussed.

  3. Lithium Dendrite Formation

    SciTech Connect

    2015-03-06

    Scientists at the Department of Energy’s Oak Ridge National Laboratory have captured the first real-time nanoscale images of lithium dendrite structures known to degrade lithium-ion batteries. The ORNL team’s electron microscopy could help researchers address long-standing issues related to battery performance and safety. Video shows annular dark-field scanning transmission electron microscopy imaging (ADF STEM) of lithium dendrite nucleation and growth from a glassy carbon working electrode and within a 1.2M LiPF6 EC:DM battery electrolyte.

  4. Lithium metal oxide electrodes for lithium batteries

    DOEpatents

    Thackeray, Michael M.; Johnson, Christopher S.; Amine, Khalil; Kang, Sun-Ho

    2010-06-08

    An uncycled preconditioned electrode for a non-aqueous lithium electrochemical cell including a lithium metal oxide having the formula xLi.sub.2-yH.sub.yO.xM'O.sub.2.(1-x)Li.sub.1-zH.sub.zMO.sub.2 in which 0lithium metal ion with an average trivalent oxidation state selected from two or more of the first row transition metals or lighter metal elements in the periodic table, and M' is one or more ions with an average tetravalent oxidation state selected from the first and second row transition metal elements and Sn. The xLi.sub.2-yH.sub.y.xM'O.sub.2.(1-x)Li.sub.1-zH.sub.zMO.sub.2 material is prepared by preconditioning a precursor lithium metal oxide (i.e., xLi.sub.2M'O.sub.3.(1-x)LiMO.sub.2) with a proton-containing medium with a pH<7.0 containing an inorganic acid. Methods of preparing the electrodes are disclosed, as are electrochemical cells and batteries containing the electrodes.

  5. On Faraday Instability in Magnetic Liquids: Ince-Erdelyi Approach Applied to the Hill Equation Describing Oscillations of a Ferrofluid Free Surface

    NASA Astrophysics Data System (ADS)

    Hennenberg, M.; Slavtchev, S.; Valchev, G.

    2013-12-01

    When an isothermal ferrofluid is submitted to an oscillating magnetic field, the initially motionless liquid free surface can start to oscillate. This physical phenomenon is similar to the Faraday instability for usual Newtonian liquids subjected to a mechanical oscillation. In the present paper, we consider the magnetic field as a sum of a constant part and a time periodic part. Two different cases for the constant part of the field, being vertical in the first one or horizontal in the second one are studied. Assuming both ferrofluid magnetization and magnetic field to be collinear, we develop the linear stability analysis of the motionless reference state taking into account the Kelvin magnetic forces. The Laplace law describing the free surface deformation reduces to Hill's equation, which is studied using the classical method of Ince and Erdelyi. Inside this framework, we obtain the transition conditions leading to the free surface oscillations.

  6. Lithium drifted germanium system

    NASA Technical Reports Server (NTRS)

    Fjarlie, E. J.

    1969-01-01

    General characteristics of the lithium-drifted germanium photodiode-Dewar-preamplifier system and particular operating instructions for the device are given. Information is included on solving operational problems.

  7. APPARATUS FOR THE PRODUCTION OF LITHIUM METAL

    DOEpatents

    Baker, P.S.; Duncan, F.R.; Greene, H.B.

    1961-08-22

    Methods and apparatus for the production of high-purity lithium from lithium halides are described. The apparatus is provided for continuously contacting a molten lithium halide with molten barium, thereby forming lithium metal and a barium halide, establishing separate layers of these reaction products and unreacted barium and lithium halide, and continuously withdrawing lithium and barium halide from the reaction zone. (AEC)

  8. Scoping studies: behavior and control of lithium and lithium aerosols

    SciTech Connect

    Jeppson, D W

    1982-01-01

    The HEDL scoping studies examining the behavior of lithium and lithium aerosols have been conducted to determine and examine potential safety and environmental issues for postulated accident conditions associated with the use of lithium as a fusion reactor blanket and/or coolant. Liquid lithium reactions with air, nitrogen, carbon dioxide and concretes have been characterized. The effectiveness of various powder extinguishing agents and methods of application were determined for lithium-air reactions. The effectiveness of various lithium aerosol collection methods were determined and the volatilization and transport of radioactive metals potentially associated with lithium-air reactions were evaluated. Liquid lithium atmosphere reactions can be safely controlled under postulated accident conditions, but special handling practices must be provided. Lithium-concrete reactions should be avoided because of the potential production of high temperatures, corrosive environment and hydrogen. Carbon microspheres are effective in extinguishing well established lithium-air reactions for the lithium quantities tested (up to 10 kg). Large mass loading of lithium aerosols can be efficiently collected with conventional air cleaning systems. Potentially radioactive species (cobalt, iron and manganese) will be volatilized in a lithium-air reaction in contact with neutron activated stainless steel.

  9. Lithium to the Rescue.

    PubMed

    Jope, Richard S; Nemeroff, Charles B

    2016-01-01

    Lithium, an element that Mother Nature has put in some drinking water sources, has been used for its curative powers for centuries. Today, it's given in capsule form as a mood stabilizer for bipolar disorder and depression. New research, however, reveals its role as a neuroprotector, and suggests that a better understanding of the role enzymes modulated by lithium play could lead to new treatments for Alzheimer's disease, Parkinson's disease, multiple sclerosis, and other neurodegenerative disorders. PMID:27408673

  10. Lithium battery management system

    DOEpatents

    Dougherty, Thomas J.

    2012-05-08

    Provided is a system for managing a lithium battery system having a plurality of cells. The battery system comprises a variable-resistance element electrically connected to a cell and located proximate a portion of the cell; and a device for determining, utilizing the variable-resistance element, whether the temperature of the cell has exceeded a predetermined threshold. A method of managing the temperature of a lithium battery system is also included.

  11. Solid-state lithium battery

    SciTech Connect

    Ihlefeld, Jon; Clem, Paul G; Edney, Cynthia; Ingersoll, David; Nagasubramanian, Ganesan; Fenton, Kyle Ross

    2014-11-04

    The present invention is directed to a higher power, thin film lithium-ion electrolyte on a metallic substrate, enabling mass-produced solid-state lithium batteries. High-temperature thermodynamic equilibrium processing enables co-firing of oxides and base metals, providing a means to integrate the crystalline, lithium-stable, fast lithium-ion conductor lanthanum lithium tantalate (La.sub.1/3-xLi.sub.3xTaO.sub.3) directly with a thin metal foil current collector appropriate for a lithium-free solid-state battery.

  12. Permeability of acetic acid across gel and liquid-crystalline lipid bilayers conforms to free-surface-area theory.

    PubMed Central

    Xiang, T X; Anderson, B D

    1997-01-01

    bilayers (8-fold), and the linear relationship between in f and sigma established for liquid-crystalline bilayers was no longer followed. However, in both gel and liquid-crystalline phases in f was found to exhibit an inverse correlation with free surface area (in f = -0.31 - 29.1/af, where af is the average free area (in square angstroms) per lipid molecule). Thus, the lipid bilayer permeability of acetic acid can be predicted from the relevant chain-packing properties in the bilayer (free surface area), regardless of whether chain ordering is varied by changes in temperature, lipid chain length, cholesterol concentration, or bilayer phase structure, provided that temperature effects on permeant dehydration and diffusion and the chain-length effects on bilayer barrier thickness are properly taken into account. PMID:8994607

  13. A perspective on experimental findings and theoretical explanations of novel dynamics at free surface and in freestanding thin films of polystyrene

    NASA Astrophysics Data System (ADS)

    Ngai, Kia L.; Prevosto, Daniele; Capaccioli, Simone

    2016-03-01

    Most studies of the dynamics at the surface and in thin films of polystyrene (PS) are focused on the change of glass transition temperature from the bulk value. In this perspective, we highlight three new developments in research on the dynamics of PS in high molecular weight (MW) freestanding PS thin films and at the surface of low MW PS. Novel findings from these developments require consideration of viscoelastic mechanisms with length scales longer than the segmental α-relaxation. The first development is the creep compliance measurements of high-MW PS thin films, probing not only the segmental α-relaxation, but also the polymer chain modes at higher compliance levels, including the sub-Rouse modes and the Rouse modes. The compliance data indicate the relaxation times of the sub-Rouse modes are reduced in thinner films like that of the segmental α-relaxation but to a much less extent. The second development is the novel observation of two glass transitions in freestanding polystyrene thin films by ellipsometry. The upper and lower glass transitions occurs, respectively, at temperatures ? and ?, both are below the bulk glass transition temperature. While the lower transition at ? is associated with the segmental α-relaxation, the only viable explanation of the origin of the upper transition at ? is from another intrinsic viscoelastic mechanism of PS, and not at different location of the film. Supported by various experiments on PS and other polymers, we show that the sub-Rouse modes are cooperative and coupled to density, and hence giving rise to the upper glass transition in freestanding PS films. The sub-Rouse relaxation times will increase on physical ageing, and bring along an increase in density of the freestanding film due to the coupling. This prediction can be checked by performing ageing experiment. The third development is the reduction of viscosity at the free surface of low MW PS. Since viscous flow of low MW PS is definitely carried out by the

  14. Hydrogen Outgassing from Lithium Hydride

    SciTech Connect

    Dinh, L N; Schildbach, M A; Smith, R A; Balazs1, B; McLean II, W

    2006-04-20

    Lithium hydride is a nuclear material with a great affinity for moisture. As a result of exposure to water vapor during machining, transportation, storage and assembly, a corrosion layer (oxide and/or hydroxide) always forms on the surface of lithium hydride resulting in the release of hydrogen gas. Thermodynamically, lithium hydride, lithium oxide and lithium hydroxide are all stable. However, lithium hydroxides formed near the lithium hydride substrate (interface hydroxide) and near the sample/vacuum interface (surface hydroxide) are much less thermally stable than their bulk counterpart. In a dry environment, the interface/surface hydroxides slowly degenerate over many years/decades at room temperature into lithium oxide, releasing water vapor and ultimately hydrogen gas through reaction of the water vapor with the lithium hydride substrate. This outgassing can potentially cause metal hydriding and/or compatibility issues elsewhere in the device. In this chapter, the morphology and the chemistry of the corrosion layer grown on lithium hydride (and in some cases, its isotopic cousin, lithium deuteride) as a result of exposure to moisture are investigated. The hydrogen outgassing processes associated with the formation and subsequent degeneration of this corrosion layer are described. Experimental techniques to measure the hydrogen outgassing kinetics from lithium hydride and methods employing the measured kinetics to predict hydrogen outgassing as a function of time and temperature are presented. Finally, practical procedures to mitigate the problem of hydrogen outgassing from lithium hydride are discussed.

  15. Dielectric and ellipsometric studies of the dynamics in thin films of isotactic poly(methylmethacrylate) with one free surface.

    PubMed

    Sharp, J S; Forrest, J A

    2003-03-01

    We have performed dielectric loss measurements at 1 kHz on thin films of isotactic poly(methyl methacrylate). A key distinction of our studies is that the samples measured were supported films with one free surface rather than films that have metallic electrodes covering both surfaces. This unique sample geometry allows us to eliminate any effects due to evaporation of metal onto the top film surface and provides a unique opportunity to make direct comparisons between dielectric loss and glass transition measurements. Film thicknesses in the range from 6 microm to 7 nm were prepared on Al coated substrates. The dielectric loss peak and ellipsometric glass transition temperature of all films were measured. The dielectric loss was found to exhibit no discernible film thickness dependence in either the temperature of the maximum loss value or the shape of the loss curve. In contrast, the measured T(g) values were found to decrease with decreasing film thickness with a maximum shift of 10 K for a 7-nm film. Dielectric measurements were also made on Al coated films and these samples also showed no shift in the temperature of the loss peak. Finally, the T(g) measurements were also made on Si substrates. These values exhibited an increasing T(g) value with film thickness with a maximum increase of approximately 15 K being measured for a 7-nm film. PMID:12689094

  16. Label-free surface-enhanced Raman scattering strategy for rapid detection of penicilloic acid in milk products.

    PubMed

    Qi, Meihui; Huang, Xiaoyan; Zhou, Yujie; Zhang, Liying; Jin, Yang; Peng, Yan; Jiang, Huijun; Du, Shuhu

    2016-04-15

    A label-free surface-enhanced Raman scattering (SERS) strategy based on silver-coated gold nanoparticles (Au@Ag NPs) was developed for rapid detection of penicilloic acid (PA) in milk products. It has been demonstrated that core size and shell thickness of Au@Ag NPs are two critical variants affecting enhancement of Raman signals by coupling of two plasma resonance absorption. The Au@Ag NPs with 26-nm core and 9-nm Ag shell exhibit excellent Raman enhancement, in particular, upon the formation of hot spots through NPs aggregation induced by interaction between target molecules and Au@Ag NPs. Compared to the early studies limited to laboratory settings, our analytical approach is simple (without sample pretreatment), less time-consuming (within ∼3 min) and inexpensive. The limit of detection of PA is 3.00 ppm, 3.00 ppm and 4.00 ppm in liquid milk, yogurt and milk powder, respectively. The label-free SERS technique offers a potential for the on-site monitoring of chemical contaminants in milk products. PMID:26617009

  17. Free surface liquid films of binary mixtures. Two-dimensional steady structures at off-critical compositions

    NASA Astrophysics Data System (ADS)

    Bribesh, Fathi A. M.; Madruga, Santiago

    2016-03-01

    We present steady non-linear solutions of films of confined polymer blends deposited on a solid substrate at off-critical concentrations with a free deformable surface. The solutions are obtained numerically using a variational form of the Cahn-Hilliard equation in the static limit, which allows for internal diffuse interfaces between the two components of the mixture. Existence of most of the branches of non-linear solutions at off-critical concentrations can be predicted from the knowledge of the branching points obtained with a linear stability analysis plus the non-linear solutions at critical concentrations. However, some families of solutions are found not to have correspondence at critical compositions. We take a value for surface tension that allows strong deformations at the sharp free upper surface. Varying the average composition and the length and thickness of the films we find a rich morphology of static films in the form of laterally structure films, layered films, droplets on the substrate, droplets at the free surface, and checkerboard structures. We show that laterally structured solutions are energetically favorable over homogeneous and other structured solutions within the whole spinodal region and even close to the absolute stability binodal boundary.

  18. Controlled synthesis of buried delta-layers of Ag nanocrystals for near-field plasmonic effects on free surfaces

    SciTech Connect

    Benzo, Patrizio; Bonafos, Caroline; Bayle, Maxime; Carles, Robert; Cattaneo, Laura; Benassayag, Gerard; Pecassou, Beatrice; Farcau, Cosmin; Muller, Dominique

    2013-05-21

    We report on the shallow synthesis by low energy ion implantation of delta-layers of Ag nanocrystals in SiO{sub 2} at few nanometers under its free surface. Transmission electron microscopy observations, ballistic simulations, and reflectance measurements are coupled to define the conditions for which the synthesis is fully controlled and when, on the contrary, this control is lost. We show that low dose implantation leads to the formation of a well-defined single plane of nanocrystals, while for larger doses, sputtering and diffusion effects limit the control of the size, position, and volume amount of these nanocrystals. This paper provides the experimental evidence of the incorporated dose saturation predicted in the literature when implanting metal ions at high doses in glass matrices. Its consequences on the particle population and the plasmonic optical response of the composite layers are carefully analyzed. We show here that this saturation phenomenon is underestimated in standard simulation predictions due to diffusion of metal atoms towards the surface and nanocrystal nucleation during the implantation process.

  19. Engineering Heteromaterials to Control Lithium Ion Transport Pathways

    DOE PAGESBeta

    Liu, Yang; Vishniakou, Siarhei; Yoo, Jinkyoung; Dayeh, Shadi A.

    2015-12-21

    Safe and efficient operation of lithium ion batteries requires precisely directed flow of lithium ions and electrons to control the first directional volume changes in anode and cathode materials. Understanding and controlling the lithium ion transport in battery electrodes becomes crucial to the design of high performance and durable batteries. Recent work revealed that the chemical potential barriers encountered at the surfaces of heteromaterials play an important role in directing lithium ion transport at nanoscale. Here, we utilize in situ transmission electron microscopy to demonstrate that we can switch lithiation pathways from radial to axial to grain-by-grain lithiation through themore » systematic creation of heteromaterial combinations in the Si-Ge nanowire system. Lastly, our systematic studies show that engineered materials at nanoscale can overcome the intrinsic orientation-dependent lithiation, and open new pathways to aid in the development of compact, safe, and efficient batteries.« less

  20. Corrosion in lithium-stainless steel thermal-convection systems

    SciTech Connect

    Tortorelli, P.F.; DeVan, J.H.; Selle, J.E.

    1980-01-01

    The corrosion of types 304L and 316 austenitic stainless steel by flowing lithium was studied in thermal-convection loops operated at 500 to 650/sup 0/C. Both weight and compositional changes were measured on specimens distributed throughout each loop and were combined with metallographic examinations to evaluate the corrosion processes. The corrosion rate and mass transfer characteristics did not significantly differ between the two austenitic stainless steels. Addition of 500 or 1700 wt ppM N to purified lithium did not increase the dissolution rate or change the attack mode of type 316 stainless steel. Adding 5 wt % Al to the lithium reduced the weight loss of this steel by a factor of 5 relative to a pure lithium-thermal-convection loop.

  1. Engineering Heteromaterials to Control Lithium Ion Transport Pathways

    SciTech Connect

    Liu, Yang; Vishniakou, Siarhei; Yoo, Jinkyoung; Dayeh, Shadi A.

    2015-12-21

    Safe and efficient operation of lithium ion batteries requires precisely directed flow of lithium ions and electrons to control the first directional volume changes in anode and cathode materials. Understanding and controlling the lithium ion transport in battery electrodes becomes crucial to the design of high performance and durable batteries. Recent work revealed that the chemical potential barriers encountered at the surfaces of heteromaterials play an important role in directing lithium ion transport at nanoscale. Here, we utilize in situ transmission electron microscopy to demonstrate that we can switch lithiation pathways from radial to axial to grain-by-grain lithiation through the systematic creation of heteromaterial combinations in the Si-Ge nanowire system. Lastly, our systematic studies show that engineered materials at nanoscale can overcome the intrinsic orientation-dependent lithiation, and open new pathways to aid in the development of compact, safe, and efficient batteries.

  2. Engineering Heteromaterials to Control Lithium Ion Transport Pathways

    PubMed Central

    Liu, Yang; Vishniakou, Siarhei; Yoo, Jinkyoung; Dayeh, Shadi A.

    2015-01-01

    Safe and efficient operation of lithium ion batteries requires precisely directed flow of lithium ions and electrons to control the first directional volume changes in anode and cathode materials. Understanding and controlling the lithium ion transport in battery electrodes becomes crucial to the design of high performance and durable batteries. Recent work revealed that the chemical potential barriers encountered at the surfaces of heteromaterials play an important role in directing lithium ion transport at nanoscale. Here, we utilize in situ transmission electron microscopy to demonstrate that we can switch lithiation pathways from radial to axial to grain-by-grain lithiation through the systematic creation of heteromaterial combinations in the Si-Ge nanowire system. Our systematic studies show that engineered materials at nanoscale can overcome the intrinsic orientation-dependent lithiation, and open new pathways to aid in the development of compact, safe, and efficient batteries. PMID:26686655

  3. Engineering Heteromaterials to Control Lithium Ion Transport Pathways

    NASA Astrophysics Data System (ADS)

    Liu, Yang; Vishniakou, Siarhei; Yoo, Jinkyoung; Dayeh, Shadi A.

    2015-12-01

    Safe and efficient operation of lithium ion batteries requires precisely directed flow of lithium ions and electrons to control the first directional volume changes in anode and cathode materials. Understanding and controlling the lithium ion transport in battery electrodes becomes crucial to the design of high performance and durable batteries. Recent work revealed that the chemical potential barriers encountered at the surfaces of heteromaterials play an important role in directing lithium ion transport at nanoscale. Here, we utilize in situ transmission electron microscopy to demonstrate that we can switch lithiation pathways from radial to axial to grain-by-grain lithiation through the systematic creation of heteromaterial combinations in the Si-Ge nanowire system. Our systematic studies show that engineered materials at nanoscale can overcome the intrinsic orientation-dependent lithiation, and open new pathways to aid in the development of compact, safe, and efficient batteries.

  4. Lithium: for harnessing renewable energy

    USGS Publications Warehouse

    Bradley, Dwight; Jaskula, Brian

    2014-01-01

    Lithium, which has the chemical symbol Li and an atomic number of 3, is the first metal in the periodic table. Lithium has many uses, the most prominent being in batteries for cell phones, laptops, and electric and hybrid vehicles. Worldwide sources of lithium are broken down by ore-deposit type as follows: closed-basin brines, 58%; pegmatites and related granites, 26%; lithium-enriched clays, 7%; oilfield brines, 3%; geothermal brines, 3%; and lithium-enriched zeolites, 3% (2013 statistics). There are over 39 million tons of lithium resources worldwide. Of this resource, the USGS estimates there to be approximately 13 million tons of current economically recoverable lithium reserves. To help predict where future lithium supplies might be located, USGS scientists study how and where identified resources are concentrated in the Earth’s crust, and they use that knowledge to assess the likelihood that undiscovered resources also exist.

  5. Rechargeable ambient temperature lithium cells

    NASA Technical Reports Server (NTRS)

    Holleck, G. L.

    1980-01-01

    The cycling performance of a secondary lithium cell with a 2-methyl THF lithium hectofluorarsenate electrolyte is discussed. Stripping efficiency, dendritization, passivation on standing, and discharge efficiency are considered.

  6. Lithium-system corrosion/erosion studies for the FMIT project

    SciTech Connect

    Bazinet, G D

    1983-04-01

    The corrosion behavior of selected materials in a liquid lithium environment has been studied in support of system and component designs for the Fusion Materials Irradiation Test (FMIT) Facility. The liquid lithium test resources and the capabilities of several laboratories were used to study specific concerns associated with the overall objective. Testing conditions ranged from approx. 3700 hours to approx. 6500 hours of exposure to flowing lithium at temperatures from 230/sup 0/C to 270/sup 0/C and static lithium at temperatures from 200/sup 0/C to 500/sup 0/C. Principal areas of investigation included lithium corrosion/erosion effects of FMIT lithium system materials (largely Type 304 and Type 304L austenitic stainless steels) and candidate materials for major system components.

  7. Improvement of the free-surface tension model in shallow water basin by using in-situ bottom-friction measurements

    NASA Astrophysics Data System (ADS)

    Alekseenko, Elena; Kuznetsov, Konstantin; Roux, Bernard

    2016-04-01

    Wind stress on the free surface is the main driving force behind the circulation of the upper part of the ocean, which in hydrodynamic models are usually defined in terms of the coefficient of surface tension (Zhang et al., 2009, Davies et al., 2003). Moreover, wave motion impacts local currents and changes sea level, impacts the transport and the stratification of the entire water column. Influence of surface waves at the bottom currents is particularly pronounced in the shallow coastal systems. However, existing methods of parameterization of the surface tension have significant limits, especially in strong wind waves (Young et al., 2001, Jones et al., 2004) due to the difficulties of measuring the characteristics of surface waves in stormy conditions. Thus, the formula for calculating the coefficient of surface tension in our day is the actual problem in modeling fluid dynamics, particularly in the context of strong surface waves. In the hydrodynamic models usually a coefficient of surface tension is calculated once at the beginning of computation as a constant that depends on the averaged wind waves characteristic. Usually cases of strongly nonlinear wind waves are not taken into account, what significantly reduces the accuracy of the calculation of the flow structures and further calculation of the other processes in water basins, such as the spread of suspended matter and pollutants. Thus, wave motion influencing the pressure on the free surface and at the bottom must be considered in hydrodynamic models particularly in shallow coastal systems. A method of reconstruction of a free-surface drag coefficient based on the measured in-situ bottom pressure fluctuations is developed and applied in a three-dimensional hydrodynamic model MARS3D, developed by the French laboratory of IFREMER (IFREMER - French Research Institute for Marine Dynamics). MARS3D solves the Navier-Stokes equations for incompressible fluid in the Boussinesq approximation and with the

  8. Improvement of the free-surface tension model in shallow water basin by using in-situ bottom-friction measurements

    NASA Astrophysics Data System (ADS)

    Alekseenko, Elena; Kuznetsov, Konstantin; Roux, Bernard

    2016-04-01

    Wind stress on the free surface is the main driving force behind the circulation of the upper part of the ocean, which in hydrodynamic models are usually defined in terms of the coefficient of surface tension (Zhang et al., 2009, Davies et al., 2003). Moreover, wave motion impacts local currents and changes sea level, impacts the transport and the stratification of the entire water column. Influence of surface waves at the bottom currents is particularly pronounced in the shallow coastal systems. However, existing methods of parameterization of the surface tension have significant limits, especially in strong wind waves (Young et al., 2001, Jones et al., 2004) due to the difficulties of measuring the characteristics of surface waves in stormy conditions. Thus, the formula for calculating the coefficient of surface tension in our day is the actual problem in modeling fluid dynamics, particularly in the context of strong surface waves. In the hydrodynamic models usually a coefficient of surface tension is calculated once at the beginning of computation as a constant that depends on the averaged wind waves characteristic. Usually cases of strongly nonlinear wind waves are not taken into account, what significantly reduces the accuracy of the calculation of the flow structures and further calculation of the other processes in water basins, such as the spread of suspended matter and pollutants. Thus, wave motion influencing the pressure on the free surface and at the bottom must be considered in hydrodynamic models particularly in shallow coastal systems. A method of reconstruction of a free-surface drag coefficient based on the measured in-situ bottom pressure fluctuations is developed and applied in a three-dimensional hydrodynamic model MARS3D, developed by the French laboratory of IFREMER (IFREMER - French Research Institute for Marine Dynamics). MARS3D solves the Navier-Stokes equations for incompressible fluid in the Boussinesq approximation and with the

  9. Stability of the lithium 'waterfall' first wall protection concept for inertial confinement fusion reactors

    SciTech Connect

    Esser, P.D.; Paul, D.D.; Abdel-Khalik, S.I.

    1981-01-01

    Uncertainties regarding the feasibility of using an annular waterfall of liquid lithium to protect the first wall in inertial confinement fusion reactor cavities have prompted a theoretical investigation of annular jet stability. Infinitesimal perturbation techniques are applied to an idealized model of the jet with disturbances acting upon either or both of the free surfaces. Dispersion relations are derived that predict the range of disturbance frequencies leading to instability, as well as the perturbation growth rates and jet break-up length. The results are extended to turbulent annular jets and are evaluated for the lithium waterfall design. It is concluded that inherent instabilities due to turbulent fluctuations will not cause the jet to break up over distances comparable to the height of the reactor cavity.

  10. Stability of the lithium ''WATERFALL'' first wall protection concept for inertial confinement fusion reactors

    SciTech Connect

    Esser, P.D.; Abel-Khalik, S.I.; Paul, D.D.

    1981-04-01

    Uncertainties regarding the feasibility of using an annular ''waterfall'' of liquid lithium to protect the first wall in inertial confinement fusion reactor cavities have prompted a theoretical investigation of annular jet stability. Infinitesimal perturbation techniques are applied to an idealized model of the jet with disturbances acting upon either or both of the free surfaces. Dispersion relations are derived that predict the range of disturbance frequencies leading to instability, as well as the perturbation growth rates and jet breakup length. The results are extended to turbulent annular jets and are evaluated for the lithium waterfall design. It is concluded that inherent instabilities due to turbulent fluctuations will not cause the jet to break up over distances comparable to the height of the reactor cavity.

  11. Experimental and Numerical Analysis of the Deformation of a Liquid Aluminum Free Surface Covered by an Oxide Layer During Induction Melting

    NASA Astrophysics Data System (ADS)

    Bansal, Akshay; Chapelle, Pierre; Delannoy, Yves; Waz, Emmanuel; Le Brun, Pierre; Bellot, Jean Pierre

    2015-10-01

    In an induction furnace, as a result of electromagnetic forces, the free surface of a liquid aluminum bath deforms and takes the form of a dome. The oxide layer that forms spontaneously on the free surface of aluminum melts may also influence the deformation by exerting an additional friction force on the metal. A non-intrusive experimental technique—Structured Light Fringe Projection—was used to measure the complete surface deformation and its fluctuations, for a varying set of operating parameters—inductor current intensity and initial liquid metal filling level inside the crucible. For an axisymmetric geometry, numerical simulations were carried out to calculate in a single framework: (i) the electromagnetic forces using the A- V formulation, (ii) the free surface deformation using the Volume of Fluid method, and (iii) the turbulent stirring of the metal using a RANS-based k-ω model. The friction force due to the oxide layer was modeled by imposing a pseudo-wall condition on the free surface, which makes the interfacial velocity very small compared to the average liquid metal pool velocity. A marked impact on the dome height due to applied friction force is observed. Finally, comparisons between the predicted and measured domes are presented.

  12. Reversibility of anodic lithium in rechargeable lithium-oxygen batteries.

    PubMed

    Shui, Jiang-Lan; Okasinski, John S; Kenesei, Peter; Dobbs, Howard A; Zhao, Dan; Almer, Jonathan D; Liu, Di-Jia

    2013-01-01

    Non-aqueous lithium-air batteries represent the next-generation energy storage devices with very high theoretical capacity. The benefit of lithium-air batteries is based on the assumption that the anodic lithium is completely reversible during the discharge-charge process. Here we report our investigation on the reversibility of the anodic lithium inside of an operating lithium-air battery using spatially and temporally resolved synchrotron X-ray diffraction and three-dimensional micro-tomography technique. A combined electrochemical process is found, consisting of a partial recovery of lithium metal during the charging cycle and a constant accumulation of lithium hydroxide under both charging and discharging conditions. A lithium hydroxide layer forms on the anode separating the lithium metal from the separator. However, numerous microscopic 'tunnels' are also found within the hydroxide layer that provide a pathway to connect the metallic lithium with the electrolyte, enabling sustained ion-transport and battery operation until the total consumption of lithium. PMID:23929396

  13. Roughness of free surfaces of bulk amorphous polymers as studied by x-ray surface scattering and atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Stone, V. W.; Jonas, A. M.; Nysten, B.; Legras, R.

    1999-08-01

    The morphology of free surfaces of polyetherimide (PEI) samples has been characterized using atomic force microscopy in noncontact mode (NC-AFM), x-ray reflectivity (XRR), and x-ray diffuse scattering (XDS). PEI slabs have been prepared by molding pellets onto float glass. In order to characterize the roughness and morphology mathematically, we considered the surfaces as being self-affine with a rms roughness σ and Hurst coefficient H up to a finite correlation length ξ. NC-AFM topographs with σ=61+/-6.3 Å showed the presence of blobs on the surface having a slight tendency to form clusters. These features are reflected in the height-height correlation function which shows the presence of ``strong'' short-range (ξ1=1064 Å, H1=0.46) and ``weak'' long-range (ξ2=14537 Å, H2=0.99) correlations. The detection of the specularly reflected contribution in XRR scans only gives access to σ, the lateral fluctuations being averaged out over the coherence area. Scans in XDS include the detection of the diffuse (off-specular) scattering arising from lateral correlations in the surface fluctuations profile and are hence sensitive to σ, ξ, and H. The XDS data have been analyzed by simultaneous fits using the distorted-wave Born approximation up to the first order. Calculations were performed using previously published approximations. Best fits to the experimental data provided strongly different correlations length values (7570 Å<=ξ<=1245 Å) indicating that the estimation of the latter by XDS is somewhat ambiguous. This is in agreement with the strong discrepancy between the correlation lengths determined with x rays and NC-AFM, which can be accounted for by the limits of the perturbation theory for interfaces with high rms roughnesses.

  14. A review of lithium deposition in lithium-ion and lithium metal secondary batteries

    NASA Astrophysics Data System (ADS)

    Li, Zhe; Huang, Jun; Yann Liaw, Bor; Metzler, Viktor; Zhang, Jianbo

    2014-05-01

    Major aspects related to lithium deposition in lithium-ion and lithium metal secondary batteries are reviewed. For lithium-ion batteries with carbonaceous anode, lithium deposition may occur under harsh charging conditions such as overcharging or charging at low temperatures. The major technical solutions include: (1) applying electrochemical models to predict the critical conditions for deposition initiation; (2) preventions by improved battery design and material modification; (3) applying adequate charging protocols to inhibit lithium deposition. For lithium metal secondary batteries, the lithium deposition is the inherent reaction during charging. The major technical solutions include: (1) the use of mechanistic models to elucidate and control dendrite initiation and growth; (2) engineering surface morphology of the lithium deposition to avoid dendrite formation via adjusting the composition and concentration of the electrolyte; (3) controlling battery working conditions. From a survey of the literature, the areas that require further study are proposed; e.g., refining the lithium deposition criteria, developing an effective AC self pre-heating method for low-temperature charging of lithium-ion batteries, and clarifying the role the solid electrolyte interphase (SEI) plays in determining the deposition morphology; to facilitate a refined control of the lithium deposition.

  15. Lithium Dinitramide as an Additive in Lithium Power Cells

    NASA Technical Reports Server (NTRS)

    Gorkovenko, Alexander A.

    2007-01-01

    Lithium dinitramide, LiN(NO2)2 has shown promise as an additive to nonaqueous electrolytes in rechargeable and non-rechargeable lithium-ion-based electrochemical power cells. Such non-aqueous electrolytes consist of lithium salts dissolved in mixtures of organic ethers, esters, carbonates, or acetals. The benefits of adding lithium dinitramide (which is also a lithium salt) include lower irreversible loss of capacity on the first charge/discharge cycle, higher cycle life, lower self-discharge, greater flexibility in selection of electrolyte solvents, and greater charge capacity. The need for a suitable electrolyte additive arises as follows: The metallic lithium in the anode of a lithium-ion-based power cell is so highly reactive that in addition to the desired main electrochemical reaction, it engages in side reactions that cause formation of resistive films and dendrites, which degrade performance as quantified in terms of charge capacity, cycle life, shelf life, first-cycle irreversible capacity loss, specific power, and specific energy. The incidence of side reactions can be reduced through the formation of a solid-electrolyte interface (SEI) a thin film that prevents direct contact between the lithium anode material and the electrolyte. Ideally, an SEI should chemically protect the anode and the electrolyte from each other while exhibiting high conductivity for lithium ions and little or no conductivity for electrons. A suitable additive can act as an SEI promoter. Heretofore, most SEI promotion was thought to derive from organic molecules in electrolyte solutions. In contrast, lithium dinitramide is inorganic. Dinitramide compounds are known as oxidizers in rocket-fuel chemistry and until now, were not known as SEI promoters in battery chemistry. Although the exact reason for the improvement afforded by the addition of lithium dinitramide is not clear, it has been hypothesized that lithium dinitramide competes with other electrolyte constituents to react with

  16. Lithium overdosage and related tests.

    PubMed

    Pigatto, Paolo D; Dell'Osso, Bernardo; Guzzi, Gianpaolo

    2016-12-01

    Lithium acts biochemically through the inositol depletion in brain cortex. At low doses, however, it is partly effective and/or ineffective, whereas in high concentrations is toxic. We would like to make one point about this review. In fact, in our view, the patient should be given a support to correct hypernatremia and even sodium levels should be tested serially-along with serum lithium concentrations-because high sodium levels reduce the rate of elimination of lithium. Lithium is mainly a neurotoxicant. Lithium-related central nervous system toxicity as well as the cardiovascular and thyroid changes are most likely due to the cations (Na2 (+) and K(+)) competition. PMID:26753697

  17. Pumped lithium loop test to evaluate advanced refractory metal alloys and simulated nuclear fuel elements

    NASA Technical Reports Server (NTRS)

    Brandenburf, G. P.; Hoffman, E. E.; Smith, J. P.

    1974-01-01

    The performance was determined of refractory metal alloys and uranium nitride fuel element specimens in flowing 1900F (1083C) lithium. The results demonstrate the suitability of the selected materials to perform satisfactorily from a chemical compatibility standpoint.

  18. Lithium Ion Batteries

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Lithium ion batteries, which use a new battery chemistry, are being developed under cooperative agreements between Lockheed Martin, Ultralife Battery, and the NASA Lewis Research Center. The unit cells are made in flat (prismatic) shapes that can be connected in series and parallel to achieve desired voltages and capacities. These batteries will soon be marketed to commercial original-equipment manufacturers and thereafter will be available for military and space use. Current NiCd batteries offer about 35 W-hr/kg compared with 110 W-hr/kg for current lithium ion batteries. Our ultimate target for these batteries is 200 W-hr/kg.

  19. LITHIUM PROPHYLAXIS IN AFFECTIVE DISORDER

    PubMed Central

    Rao, A. Venkoba; Hariharasubramanian, N.; Devi, S. Parvathi; Sugumar, A.; Srinivasan, V.

    1982-01-01

    SUMMARY Out of 108 patients on the rolls in the Lithium clinic, Madurai Medical College and Govt. Rajaji Hospital, Madurai, India, 47 patients suffering from affective disorders receiving lithium continuously for more than three years were analysed with a view to study the recurrences. Thirteen suffered no relapses while on lithium while nineteen experienced them while on lithium. Four were free from recurrences after lithium was withdrawn- Seven defaulted but suffered recurrences while in four the drug was withdrawn and in both the groups remission was achieved with re-administration of lithium. The study reveals that lithium besides averting the recurrences can reduce the frequency, number, duration, intensity of episodes and improve the amenability to drugs. Among the symptoms, suicidal ideas and behaviour and insight were found to be influenced favourably by lithium. Among the factors that help favourable response to lithium were a positive family history of affective disorder, in the first degree relatives and lesser frequency and number of episodes in the pre-lithium period. A reappraisal of the natural history of the illness is called for in the light of lithium prophylaxis of manic depressive psychosis. PMID:21965880

  20. 77 FR 28259 - Mailings of Lithium Batteries

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-14

    ... for mailpieces containing lithium metal or lithium-ion cells or batteries and applies regardless of...'' instead of ``lithium content'' for secondary lithium-ion batteries when describing maximum quantity limits...-ion (Rechargeable) Cells and Batteries Small consumer-type lithium-ion cells and batteries like...

  1. Diagnostics for liquid lithium experiments in CDX-U

    SciTech Connect

    Kaita, R.; Efthimion, P.; Hoffman, D.; Jones, B.; Kugel, H.; Majeski, R.; Munsat, T.; Raftopoulos, S.; Taylor, G.; Timberlake, J.

    2001-01-01

    A flowing liquid lithium first wall or divertor target could virtually eliminate the concerns with power density and erosion, tritium retention, and cooling associated with solid walls in fusion reactors. To investigate the interaction of a spherical torus plasma with liquid lithium limiters, large area divertor targets, and walls, discharges will be established in the Current Drive Experiment-Upgrade (CDX-U) where the plasma--wall interactions are dominated by liquid lithium surfaces. Among the unique CDX-U lithium diagnostics is a multilayer mirror (MLM) array, which will monitor the 13.5 nm LiIII line for core lithium concentrations. Additional spectroscopic diagnostics include a grazing incidence extreme ultraviolet (XUV) spectrometer (STRS) and a filterscope system to monitor D{sub {alpha}} and various impurity lines local to the lithium limiter. Profile data will be obtained with a multichannel tangential bolometer and a multipoint Thomson scattering system configured to give enhanced edge resolution. Coupons on the inner wall of the CDX-U vacuum vessel will be used for surface analysis. A 10000 frame per second fast visible camera and an IR camera will also be available.

  2. Diagnostics for liquid lithium experiments in CDX-U

    SciTech Connect

    R. Kaita; P. Efthimion; D. Hoffman; B. Jones; H. Kugel; R. Majeski; T. Munsat; S. Raftopoulos; G. Taylor; J. Timberlake; V. Soukhanovskii; D. Stutman; M. Iovea; M. Finkenthal; R. Doerner; S. Luckhardt; R. Maingi; R. Causey

    2000-06-21

    A flowing liquid lithium first wall or diverter target could virtually eliminate the concerns with power density and erosion, tritium retention, and cooling associated with solid walls in fusion reactors. To investigate the interaction of a spherical torus plasma with liquid lithium limiters, large area diverter targets, and walls, discharges will be established in the Current Drive Experiment-Upgrade (CDX-U) where the plasma-wall interactions are dominated by liquid lithium surfaces. Among the unique CDX-U lithium diagnostics is a multi-layer mirror (MLM) array, which will monitor the 135 {angstrom} LiIII line for core lithium concentrations. Additional spectroscopic diagnostics include a grazing incidence XUV spectrometer (STRS) and a filterscope system to monitor D{sub {alpha}} and various impurity lines local to the lithium limiter. Profile data will be obtained with a multichannel tangential bolometer and a multipoint Thomson scattering system configured to give enhanced edge resolution. Coupons on th e inner wall of the CDX-U vacuum vessel will be used for surface analysis. A 10,000 frame per second fast visible camera and an IR camera will also be available.

  3. Bioavailability of lithium from lithium citrate syrup versus conventional lithium carbonate tablets.

    PubMed

    Guelen, P J; Janssen, T J; De Witte, T C; Vree, T B; Benson, K

    1992-10-01

    The bioavailability of lithium citrate syrup was compared with that of regular lithium carbonate tablets in 18 healthy male human volunteers. Blood samples were collected up to 48 h after dosing. Lithium serum concentrations were determined by means of AAS. The absorption rate following oral administration of the syrup was greater (tmax 0.8 h) than following administration of regular tablets (tmax 1.4 h). Maximum lithium serum concentrations, however, were only about 10 per cent higher after syrup dosing and serum concentrations resulting from syrup and tablets were almost superimposable from 2 h after dosing. The terminal half-life of lithium was found to be 22 h after syrup as well as after tablet dosing. No side-effects were observed during the study. The bioavailability of lithium from syrup relative to tablets was found to be bioequivalent with respect to the maximum lithium serum concentration and the extent of drug absorption (AUC). PMID:1489941

  4. Hydrodynamic Modeling of Free Surface Interactions and Implications for P and Rg Waves Recorded on the Source Physics Experiments

    NASA Astrophysics Data System (ADS)

    Larmat, C. S.; Rougier, E.; Knight, E.; Yang, X.; Patton, H. J.

    2013-12-01

    A goal of the Source Physics Experiments (SPE) is to develop explosion source models expanding monitoring capabilities beyond empirical methods. The SPE project combines field experimentation with numerical modelling. The models take into account non-linear processes occurring from the first moment of the explosion as well as complex linear propagation effects of signals reaching far-field recording stations. The hydrodynamic code CASH is used for modelling high-strain rate, non-linear response occurring in the material near the source. Our development efforts focused on incorporating in-situ stress and fracture processes. CASH simulates the material response from the near-source, strong shock zone out to the small-strain and ultimately the elastic regime where a linear code can take over. We developed an interface with the Spectral Element Method code, SPECFEM3D, that is an efficient implementation on parallel computers of a high-order finite element method. SPECFEM3D allows accurate modelling of wave propagation to remote monitoring distance at low cost. We will present CASH-SPECFEM3D results for SPE1, which was a chemical detonation of about 85 kg of TNT at 55 m depth in a granitic geologic unit. Spallation was observed for SPE1. Keeping yield fixed we vary the depth of the source systematically and compute synthetic seismograms to distances where the P and Rg waves are separated, so that analysis can be performed without concern about interference effects due to overlapping energy. We study the time and frequency characteristics of P and Rg waves and analyse them in regard to the impact of free-surface interactions and rock damage resulting from those interactions. We also perform traditional CMT inversions as well as advanced CMT inversions, developed at LANL to take into account the damage. This will allow us to assess the effect of spallation on CMT solutions as well as to validate our inversion procedure. Further work will aim to validate the developed

  5. Lithium disulfide battery

    DOEpatents

    Kaun, Thomas D.

    1988-01-01

    A negative electrode limited secondary electrochemical cell having dense FeS.sub.2 positive electrode operating exclusively on the upper plateau, a Li alloy negative electrode and a suitable lithium-containing electrolyte. The electrolyte preferably is 25 mole percent LiCl, 38 mole percent LiBr and 37 mole percent KBr. The cell may be operated isothermally.

  6. Lithium ion conducting electrolytes

    DOEpatents

    Angell, C. Austen; Liu, Changle

    1996-01-01

    A liquid, predominantly lithium-conducting, ionic electrolyte having exceptionally high conductivity at temperatures of 100.degree. C. or lower, including room temperature, and comprising the lithium salts selected from the group consisting of the thiocyanate, iodide, bromide, chloride, perchlorate, acetate, tetrafluoroborate, perfluoromethane sulfonate, perfluoromethane sulfonamide, tetrahaloaluminate, and heptahaloaluminate salts of lithium, with or without a magnesium-salt selected from the group consisting of the perchlorate and acetate salts of magnesium. Certain of the latter embodiments may also contain molecular additives from the group of acetonitrile (CH.sub.3 CN) succinnonitrile (CH.sub.2 CN).sub.2, and tetraglyme (CH.sub.3 --O--CH.sub.2 --CH.sub.2 --O--).sub.2 (or like solvents) solvated to a Mg.sup.+2 cation to lower the freezing point of the electrolyte below room temperature. Other particularly useful embodiments contain up to about 40, but preferably not more than about 25, mol percent of a long chain polyether polymer dissolved in the lithium salts to provide an elastic or rubbery solid electrolyte of high ambient temperature conductivity and exceptional 100.degree. C. conductivity. Another embodiment contains up to about but not more than 10 mol percent of a molecular solvent such as acetone.

  7. Lithium ion conducting electrolytes

    DOEpatents

    Angell, C.A.; Liu, C.

    1996-04-09

    A liquid, predominantly lithium-conducting, ionic electrolyte is described having exceptionally high conductivity at temperatures of 100 C or lower, including room temperature, and comprising the lithium salts selected from the group consisting of the thiocyanate, iodide, bromide, chloride, perchlorate, acetate, tetrafluoroborate, perfluoromethane sulfonate, perfluoromethane sulfonamide, tetrahaloaluminate, and heptahaloaluminate salts of lithium, with or without a magnesium-salt selected from the group consisting of the perchlorate and acetate salts of magnesium. Certain of the latter embodiments may also contain molecular additives from the group of acetonitrile (CH{sub 3}CN), succinnonitrile (CH{sub 2}CN){sub 2}, and tetraglyme (CH{sub 3}--O--CH{sub 2}--CH{sub 2}--O--){sub 2} (or like solvents) solvated to a Mg{sup +2} cation to lower the freezing point of the electrolyte below room temperature. Other particularly useful embodiments contain up to about 40, but preferably not more than about 25, mol percent of a long chain polyether polymer dissolved in the lithium salts to provide an elastic or rubbery solid electrolyte of high ambient temperature conductivity and exceptional 100 C conductivity. Another embodiment contains up to about but not more than 10 mol percent of a molecular solvent such as acetone. 2 figs.

  8. Lithium and Pregnancy

    MedlinePlus

    ... role in the rate of miscarriage, which include maternal age, gestational age, and history of previous miscarriage that ... Studies on children up to seven years of age who were exposed to lithium during pregnancy did not find significant physical, mental, or behavioral ...

  9. Lithium thionyl chloride battery

    SciTech Connect

    Saathoff, D.J.; Venkatasetty, H.V.

    1982-10-19

    The discharge rate and internal conductivity of electrochemical cell including a lithium anode, and a cathode and an electrolyte including LiAlCl4 and SOC2 is improved by the addition of an amount of a mixture containing AlCl3 and butyl pyridinium chloride.

  10. Lithium battery discharge tests

    NASA Technical Reports Server (NTRS)

    Johnson, C. J.

    1980-01-01

    The long term discharge of a variety of lithium cells was characterized and the susceptibility of the cells to chemical variation during the slow discharge was tested. A shunt resistor was set across the terminals to monitor the voltage as a function of time. Failures were identified by premature voltage drops.

  11. Computation of turbulent flow in a thin liquid layer of fluid involving a hydraulic jump

    NASA Technical Reports Server (NTRS)

    Rahman, M. M.; Faghri, A.; Hankey, W. L.

    1991-01-01

    Numerically computed flow fields and free surface height distributions are presented for the flow of a thin layer of liquid adjacent to a solid horizontal surface that encounters a hydraulic jump. Two kinds of flow configurations are considered: two-dimensional plane flow and axisymmetric radial flow. The computations used a boundary-fitted moving grid method with a k-epsilon model for the closure of turbulence. The free surface height was determined by an optimization procedure which minimized the error in the pressure distribution on the free surface. It was also checked against an approximate procedure involving integration of the governing equations and use of the MacCormack predictor-corrector method. The computed film height also compared reasonably well with previous experiments. A region of recirculating flow was found to be present adjacent to the solid boundary near the location of the jump, which was caused by a rapid deceleration of the flow.

  12. The history of lithium therapy

    PubMed Central

    Shorter, Edward

    2013-01-01

    The use of lithium in psychiatry goes back to the mid-19th century. Early work, however, was soon forgotten, and John Cade is credited with reintroducing lithium to psychiatry for mania in 1949. Mogens Schou undertook a randomly controlled trial for mania in 1954, and in the course of that study became curious about lithium as a prophylactic for depressive illness. In 1970, the United States became the 50th country to admit lithium to the marketplace. Meanwhile, interest in lithium for the prophylaxis of depression was growing apace and today the agent is widely prescribed for that indication, even though it has not been accepted by the Food and Drug Administration. Lithium was almost derailed by a small group of opponents from the Maudsley Hospital and its status today is threatened by the “mood stabilizers.” PMID:19538681

  13. Experimental lithium system. Final report

    SciTech Connect

    Kolowith, R.; Berg, J.D.; Miller, W.C.

    1985-04-01

    A full-scale mockup of the Fusion Materials Irradiation Test (FMIT) Facility lithium system was built at the Hanford Engineering Development Laboratory (HEDL). This isothermal mockup, called the Experimental Lithium System (ELS), was prototypic of FMIT, excluding the accelerator and dump heat exchanger. This 3.8 m/sup 3/ lithium test loop achieved over 16,000 hours of safe and reliable operation. An extensive test program demonstrated satisfactory performance of the system components, including the HEDL-supplied electromagnetic lithium pump, the lithium jet target, the purification and characterization hardware, as well as the auxiliary argon and vacuum systems. Experience with the test loop provided important information on system operation, performance, and reliability. This report presents a complete overview of the entire Experimental Lithium System test program and also includes a summary of such areas as instrumentation, coolant chemistry, vapor/aerosol transport, and corrosion.

  14. Membranes in Lithium Ion Batteries

    PubMed Central

    Yang, Min; Hou, Junbo

    2012-01-01

    Lithium ion batteries have proven themselves the main choice of power sources for portable electronics. Besides consumer electronics, lithium ion batteries are also growing in popularity for military, electric vehicle, and aerospace applications. The present review attempts to summarize the knowledge about some selected membranes in lithium ion batteries. Based on the type of electrolyte used, literature concerning ceramic-glass and polymer solid ion conductors, microporous filter type separators and polymer gel based membranes is reviewed. PMID:24958286

  15. Safety and diagnostic systems on the Liquid Lithium Test Stand (LLTS)

    NASA Astrophysics Data System (ADS)

    Schwartz, J. A.; Jaworski, M. A.; Ellis, R.; Kaita, R.; Mozulay, R.

    2013-10-01

    The Liquid Lithium Test Stand (LLTS) is a test bed for development of flowing liquid lithium systems for plasma-facing components at PPPL. LLTS is designed to test operation of liquid lithium under vacuum, including flowing, solidifying (such as would be the case at the end of plasma operations), and re-melting. Constructed of stainless steel, LLTS is a closed loop of pipe with two reservoirs and a pump, as well as diagnostics for temperature, flow rate, and pressure. Since liquid lithium is a highly reactive material, special care must be taken when designing such a system. These include a permanent-magnet MHD pump and MHD flow meter that have no mechanical components in direct contact with the liquid lithium. The LLTS also includes an expandable 24-channel leak-detector interlock system which cuts power to heaters and the pump if any lithium leaks from a pipe joint. Design for the interlock systems and flow meter are presented. This work is supported by US DOE Contract DE-AC02-09CH11466.

  16. LITHIUM TOXICITY - A DESCRIPTIVE STUDY

    PubMed Central

    Kumar, Ratanendra; Deb, Jayant Kumar; Sinha, Baxi Neeraj Prasad; Sinha, Vinod Kumar

    2001-01-01

    Lithium is the treatment for acute mania and bipolar disorders. Ever since its introduction in the psychiatric arsenal, case reports of toxicity have been appearing in the literature at regular intervals. This study was thus carried out to study the presentation and associated features of lithium toxicity. In this retrospective study, case record files of all patients suspected to have developed lithium toxicity during a five year period were retrieved. It was found that toxicity presented most commonly with cerebellar symptoms and appeared at lower serum levels. Lithium could be restarted albeit at a lower dose and with a gradual titration in a number of cases. PMID:21407839

  17. Lithium batteries with laminar anodes

    SciTech Connect

    Bruder, A.H.

    1986-11-04

    This patent describes a laminar electrical cell, comprising an anode, a cathode, and an electrolyte permeable separator between the anode and the cathode. The anode consists essentially of a layer of lithium having at least one surface of unreacted lithium metal in direct contact with and adhered to a layer of conductive plastic with no intermediate adhesive promoting adjuncts. The cathode comprises a slurry of MnO/sub 2/ and carbon particles in a solution of a lithium salt in an organic solvent, the solution permeating the separator and being in contact with the lithium.

  18. Blockage effects on the hydrodynamic performance of a marine cross-flow turbine.

    PubMed

    Consul, Claudio A; Willden, Richard H J; McIntosh, Simon C

    2013-02-28

    This paper explores the influence of blockage and free-surface deformation on the hydrodynamic performance of a generic marine cross-flow turbine. Flows through a three-bladed turbine with solidity 0.125 are simulated at field-test blade Reynolds numbers, O(10(5)-10(6)), for three different cross-stream blockages: 12.5, 25 and 50 per cent. Two representations of the free-surface boundary are considered: rigid lid and deformable free surface. Increasing the blockage is observed to lead to substantial increases in the power coefficient; the highest power coefficient computed is 1.23. Only small differences are observed between the two free-surface representations, with the deforming free-surface turbine out-performing the rigid lid turbine by 6.7 per cent in power at the highest blockage considered. This difference is attributed to the increase in effective blockage owing to the deformation of the free surface. Hydrodynamic efficiency, the ratio of useful power generated to overall power removed from the flow, is found to increase with blockage, which is consistent with the presence of a higher flow velocity through the core of the turbine at higher blockage ratios. Froude number is found to have little effect on thrust and power coefficients, but significant influence on surface elevation drop across the turbine. PMID:23319712

  19. Hysteresis and the transition between axisymmetric flow and wave flow in the baroclinic annulus

    NASA Technical Reports Server (NTRS)

    Miller, Timothy L.; Butler, Karen A.

    1991-01-01

    A numerical model is employed to establish the transitions between axisymmetric flow and wave flow in the rotating, differentially heated annulus experiments of Fein for both rigid lid and free surface cases. It is shown that, for most of the transitions, the method of computing a steady axisymmetric flow and then testing its linear stability to wave disturbance results in good agreement with the experiments. Implications for the investigation of the dynamics of the earth's atmosphere are considered.

  20. Effect of evaporation or infiltration on the free surface of groundwater in certain problems of underground hydromechanics

    NASA Astrophysics Data System (ADS)

    Bereslavskii, E. N.

    2016-06-01

    Within the framework of the theory of plane steady filtration of an incompressible fluid according to Darcy's law, two limiting schemes modeling the filtration flows under the Joukowski tongue through a soil massif spread over an impermeable foundation or strongly permeable confined water-bearing horizon are considered.

  1. Separator for lithium batteries and lithium batteries including the separator

    SciTech Connect

    Foster, D.L.

    1989-03-14

    A multilayer separator is described for preventing the internal shorting of lithium batteries, the multilayer separator including porous membranes and an electroactive polymeric material contained within the separator layers wherein the polymer is one that will react with any lithium dendrites that could penetrate the separator thus preventing an internal short circuit of the cell.

  2. Effects of dynamically variable saturation and matrix-conduit coupling of flow in karst aquifers

    USGS Publications Warehouse

    Reimann, T.; Geyer, T.; Shoemaker, W.B.; Liedl, R.; Sauter, M.

    2011-01-01

    Well-developed karst aquifers consist of highly conductive conduits and a relatively low permeability fractured and/or porous rock matrix and therefore behave as a dual-hydraulic system. Groundwater flow within highly permeable strata is rapid and transient and depends on local flow conditions, i.e., pressurized or nonpressurized flow. The characterization of karst aquifers is a necessary and challenging task because information about hydraulic and spatial conduit properties is poorly defined or unknown. To investigate karst aquifers, hydraulic stresses such as large recharge events can be simulated with hybrid (coupled discrete continuum) models. Since existing hybrid models are simplifications of the system dynamics, a new karst model (ModBraC) is presented that accounts for unsteady and nonuniform discrete flow in variably saturated conduits employing the Saint-Venant equations. Model performance tests indicate that ModBraC is able to simulate (1) unsteady and nonuniform flow in variably filled conduits, (2) draining and refilling of conduits with stable transition between free-surface and pressurized flow and correct storage representation, (3) water exchange between matrix and variably filled conduits, and (4) discharge routing through branched and intermeshed conduit networks. Subsequently, ModBraC is applied to an idealized catchment to investigate the significance of free-surface flow representation. A parameter study is conducted with two different initial conditions: (1) pressurized flow and (2) free-surface flow. If free-surface flow prevails, the systems is characterized by (1) a time lag for signal transmission, (2) a typical spring discharge pattern representing the transition from pressurized to free-surface flow, and (3) a reduced conduit-matrix interaction during free-surface flow. Copyright 2011 by the American Geophysical Union.

  3. Thermocapillary flow on superhydrophobic surfaces

    NASA Astrophysics Data System (ADS)

    Baier, Tobias; Steffes, Clarissa; Hardt, Steffen

    2010-09-01

    A liquid in Cassie-Baxter state above a structured superhydrophobic surface is ideally suited for surface driven transport due to its large free surface fraction in close contact to a solid. We investigate thermal Marangoni flow over a superhydrophobic array of fins oriented parallel or perpendicular to an applied temperature gradient. In the Stokes limit we derive an analytical expression for the bulk flow velocity above the surface and compare it with numerical solutions of the Navier-Stokes equation. Even for moderate temperature gradients comparatively large flow velocities are induced, suggesting to utilize this principle for microfluidic pumping.

  4. Critical Velocity in Open Capillary Channel Flows

    NASA Technical Reports Server (NTRS)

    Rosendahl, Uwe; Dreyer, Michael E.; Rath, Hans J.; Motil, Brian; Singh, Bhim S. (Technical Monitor)

    2001-01-01

    We investigate forced liquid flows through open capillary channels with free surfaces experimentally. The experiments were performed under low gravity conditions in the Bremen Drop Tower and on board the sounding rocket TEXUS-37. Open capillary channels (vanes) are used in surface tension tanks to transport the propellant and to provide a flow path for the bubble-free liquid supply to the thrusters. Since the free surfaces can only withstand a certain pressure differential between the liquid and ambient, the flow rate in the channel is limited. The maximum flow rate is achieved when the surfaces collapse and gas is ingested into the outlet. Since experimental and theoretical data of this flow rate limitation is lacking, the safety factors for the application of vanes in surface tension tanks must be unnecessary high. The aim of the investigation is to determine the maximum liquid flow rate and the corresponding critical flow velocity. The characteristic nondimensional parameters, OHNESORGE number, and gap ratio, cover a wide range of usual vanes. For the theoretical approach a one-dimensional momentum balance was set up. The numerical solution yields the maximum volume flux and the position of the free surface in good agreement with the experiments.

  5. Boundary Integral Solutions to Three-Dimensional Unconfined Darcy's Flow

    NASA Astrophysics Data System (ADS)

    Lennon, Gerard P.; Liu, Philip L.-F.; Liggett, James A.

    1980-08-01

    The boundary integral equation method (BIEM) is used to solve three-dimensional potential flow problems in porous media. The problems considered here are time dependent and have a nonlinear boundary condition on the free surface. The entire boundary, including the moving free surface, discretized into linear finite elements for the purpose of evaluating the boundary integrals. The technique allows transient, three-dimensional problems to be solved with reasonable computational costs. Numerical examples include recharge through rectangular and circular areas and seepage flow from a surface pond. The examples are used to illustrate the method and show the nonlinear effects.

  6. Solid lithium-ion electrolyte

    DOEpatents

    Zhang, J.G.; Benson, D.K.; Tracy, C.E.

    1998-02-10

    The present invention relates to the composition of a solid lithium-ion electrolyte based on the Li{sub 2}O--CeO{sub 2}--SiO{sub 2} system having good transparent characteristics and high ion conductivity suitable for uses in lithium batteries, electrochromic devices and other electrochemical applications. 12 figs.

  7. Intercell connector for lithium batteries

    SciTech Connect

    Bruder, A.H.

    1984-10-16

    Laminar batteries of series connected cells comprising lithium anodes and an electrolyte containing a passivating solvent reactive with lithium in which the cells are electrically connected in series by intercell barriers comprising outer layers of electrochemically inert electronically conducting material in contact with the electrochemically active anode and cathode of adjacent cells and a layer of metal foil between the electrochemically inert layers.

  8. Solid lithium-ion electrolyte

    DOEpatents

    Zhang, Ji-Guang; Benson, David K.; Tracy, C. Edwin

    1998-01-01

    The present invention relates to the composition of a solid lithium-ion electrolyte based on the Li.sub.2 O--CeO.sub.2 --SiO.sub.2 system having good transparent characteristics and high ion conductivity suitable for uses in lithium batteries, electrochromic devices and other electrochemical applications.

  9. Progress in secondary lithium batteries

    NASA Technical Reports Server (NTRS)

    Holleck, G. L.

    1982-01-01

    The lithium/molybdenum trisulfide system is discussed. This system has a higher potential energy density than that of lithium/titanium disulfide. Possible energy densities and performance values for cells, projected from preliminary data obtained on small cells, are summarized. The electrode structure is emphasized as an important factor in the decreasing of capacity upon cycling.

  10. Improved Carbon Anodes For Rechargeable Lithium Cells

    NASA Technical Reports Server (NTRS)

    Huang, Chen-Kuo; Surampudi, Subbarao; Attia, Alan; Halpert, Gerald

    1994-01-01

    Carbon anodes for rechargeable lithium cells improved by choosing binder contents and fabrication conditions to achieve maximum porosity, uniform loading, and maximum reversible lithium capacity. Stacking electrodes under pressure during assembly of cells increases cyclability of lithium. Rechargeable, high-energy-density lithium cells containing improved carbon anodes find use in spacecraft, military, communications, automotive, and other demanding applications.

  11. Solvability of Initial-Boundary Value Problems for Euler's Equations for Flows of AN Ideal Incompressible Nonhomogeneous Fluid and AN Ideal Barotropic Fluid Bounded by Free Surfaces

    NASA Astrophysics Data System (ADS)

    Sedenko, V. I.

    1995-02-01

    The Nishida version of the abstract nonlinear Cauchy-Kovalevskaya theorem is used to obtain the results indicated in the title. In this connection, one has to construct special scales of Banach spaces and to estimate in them the solutions of elliptic equations.Bibliography: 16 titles.

  12. Lithium Treatment for Psychiatric Disorders

    PubMed Central

    Maletzky, Barry M.; Shore, James H.

    1978-01-01

    Although used around the world since 1949, lithium has come into extensive use in psychiatry in the United States only within the past decade. Before initiating treatment with this drug, physicians must be familiar with the diagnostic scheme of the major affective disorders, the indications and contraindications to lithium's use, and its principles of treatment, including evaluation before lithium therapy, criteria for monitoring blood levels and signs of impending toxicity. Despite earlier reports about the toxicity of lithium when it was promoted as a salt substitute, lithium is a safe drug. Its use not only has revolutionized the treatment of the major affective disorders, but has opened up new and broad avenues of research into the regulation of man's emotions. PMID:664651

  13. HOW RELIABLE IS 24 HOUR SERUM LITHIUM LEVEL AFTER A TEST DOSE OF LITHIUM IN PREDICTING OPTIMAL LITHIUM DOSE?

    PubMed Central

    Kuruvilla, K.; Shaji, K.S.

    1989-01-01

    SUMMARY 57% of a group of 35 patients treated with Lithium Carbonate at dosages predicted by the nomogram suggested by Cooper et al (1973) failed to reach therapeutic levels of serum lithium. This finding casts serious doubts on the usefulness of the claim by Cooper et al (1973 & 1976) that 24 hour serum lithium level after a test dose of 600 mg. lithium can predict the daily lithium dose. PMID:21927360

  14. Thermal Pollution Mathematical Model. Volume 6: Verification of Three-Dimensional Free-Surface Model at Anclote Anchorage. [environment impact of thermal discharges from power plants

    NASA Technical Reports Server (NTRS)

    Lee, S. S.; Sengupta, S.; Tuann, S. Y.; Lee, C. R.

    1980-01-01

    The free-surface model presented is for tidal estuaries and coastal regions where ambient tidal forces play an important role in the dispersal of heated water. The model is time dependent, three dimensional, and can handle irregular bottom topography. The vertical stretching coordinate is adopted for better treatment of kinematic condition at the water surface. The results include surface elevation, velocity, and temperature. The model was verified at the Anclote Anchorage site of Florida Power Company. Two data bases at four tidal stages for winter and summer conditions were used to verify the model. Differences between measured and predicted temperatures are on an average of less than 1 C.

  15. Lithium orotate, carbonate and chloride: pharmacokinetics, polyuria in rats.

    PubMed Central

    Smith, D F

    1976-01-01

    1 The pharmacokinetics of the lithium ion administered as lithium orotate were studied in rats. Parallel studies were carried out with lithium carbonate and lithium chloride. 2 No differences in the uptake, distribution and excretion of the lithium ion were observed between lithium orotate, lithium carbonate and lithium chloride after single intraperitoneal, subcutaneous or intragastric injections (0.5-1.0 mEq lithium/kg) or after administration of the lithium salts for 20 days in the food. 3 The findings oppose the notion that the pharmacokinetics of the lithium ion given as lithium orotate differ from lithium chloride or lithium carbonate. 4 Polyuria and polydipsia developed more slowly in rats given lithium orotate than in those given lithium carbonate or lithium chloride, perhaps due to an effect of the orotate anion. PMID:1260219

  16. Evaluation of tantalum-alloy-clad uranium mononitride fuel specimens from 7500-hour, 1040 C pumped-lithium-loop test

    NASA Technical Reports Server (NTRS)

    Watson, G. K.

    1974-01-01

    Simulated nuclear fuel element specimens, consisting of uranium mononitride (UN) fuel cylinders clad with tungsten-lined T-111, were exposed for up to 7500 hr at 1040 C (1900 F) in a pumped-lithium loop. The lithium flow velocity was 1.5 m/sec (5 ft/sec) in the specimen test section. No evidence of any compatibility problems between the specimens and the flowing lithium was found based on appearance, weight change, chemistry, and metallography. Direct exposure of the UN to the lithium through a simulated cladding crack resulted in some erosion of the UN in the area of the defect. The T-111 cladding was ductile after lithium exposure, but it was sensitive to hydrogen embrittlement during post-test handling.

  17. Flow visualization experiments in a porous nozzle

    NASA Technical Reports Server (NTRS)

    Cielak, Z.; Kinney, R. B.; Perkins, H. C.

    1973-01-01

    An experimental approach is described for the study of nozzle flows with large wall-transpiration rates. Emphasizing a qualitative understanding of the flow, the technique uses the hydraulic analogy, whereby a compressible gas flow is simulated by a water flow having a free surface. For simplicity, the simulated gas flow is taken to be two-dimensional. A nozzle with porous walls in the throat region has been developed for use on a water table. A technique for visualizing the transpired fluid has also been devised. These are discussed, and preliminary results are presented which illustrate the success of the experimental approach.

  18. Finite element flow analysis; Proceedings of the Fourth International Symposium on Finite Element Methods in Flow Problems, Chuo University, Tokyo, Japan, July 26-29, 1982

    NASA Astrophysics Data System (ADS)

    Kawai, T.

    Among the topics discussed are the application of FEM to nonlinear free surface flow, Navier-Stokes shallow water wave equations, incompressible viscous flows and weather prediction, the mathematical analysis and characteristics of FEM, penalty function FEM, convective, viscous, and high Reynolds number FEM analyses, the solution of time-dependent, three-dimensional and incompressible Navier-Stokes equations, turbulent boundary layer flow, FEM modeling of environmental problems over complex terrain, and FEM's application to thermal convection problems and to the flow of polymeric materials in injection molding processes. Also covered are FEMs for compressible flows, including boundary layer flows and transonic flows, hybrid element approaches for wave hydrodynamic loadings, FEM acoustic field analyses, and FEM treatment of free surface flow, shallow water flow, seepage flow, and sediment transport. Boundary element methods and FEM computational technique topics are also discussed. For individual items see A84-25834 to A84-25896

  19. Electron backscatter diffraction applied to lithium sheets prepared by broad ion beam milling.

    PubMed

    Brodusch, Nicolas; Zaghib, Karim; Gauvin, Raynald

    2015-01-01

    Due to its very low hardness and atomic number, pure lithium cannot be prepared by conventional methods prior to scanning electron microscopy analysis. Here, we report on the characterization of pure lithium metallic sheets used as base electrodes in the lithium-ion battery technology using electron backscatter diffraction (EBSD) and X-ray microanalysis using energy dispersive spectroscopy (EDS) after the sheet surface was polished by broad argon ion milling (IM). No grinding and polishing were necessary to achieve the sufficiently damage free necessary for surface analysis. Based on EDS results the impurities could be characterized and EBSD revealed the microsctructure and microtexture of this material with accuracy. The beam damage and oxidation/hydration resulting from the intensive use of IM and the transfer of the sample into the microscope chamber was estimated to be <50 nm. Despite the fact that the IM process generates an increase of temperature at the specimen surface, it was assumed that the milling parameters were sufficient to minimize the heating effect on the surface temperature. However, a cryo-stage should be used if available during milling to guaranty a heating artefact free surface after the milling process. PMID:25280344

  20. Lithium electric dipole polarizability

    SciTech Connect

    Puchalski, M.; KePdziera, D.; Pachucki, K.

    2011-11-15

    The electric dipole polarizability of the lithium atom in the ground state is calculated including relativistic and quantum electrodynamics corrections. The obtained result {alpha}{sub E}=164.0740(5) a.u. is in good agreement with the less accurate experimental value of 164.19(1.08) a.u. The small uncertainty of about 3 parts per 10{sup 6} comes from the approximate treatment of quantum electrodynamics corrections. Our theoretical result can be considered as a benchmark for more general atomic structure methods and may serve as a reference value for the relative measurement of polarizabilities of the other alkali-metal atoms.

  1. Lithium niobate explosion monitor

    DOEpatents

    Bundy, C.H.; Graham, R.A.; Kuehn, S.F.; Precit, R.R.; Rogers, M.S.

    1990-01-09

    Monitoring explosive devices is accomplished with a substantially z-cut lithium niobate crystal in abutment with the explosive device. Upon impact by a shock wave from detonation of the explosive device, the crystal emits a current pulse prior to destruction of the crystal. The current pulse is detected by a current viewing transformer and recorded as a function of time in nanoseconds. In order to self-check the crystal, the crystal has a chromium film resistor deposited thereon which may be heated by a current pulse prior to detonation. This generates a charge which is detected by a charge amplifier. 8 figs.

  2. Lithium niobate explosion monitor

    DOEpatents

    Bundy, Charles H.; Graham, Robert A.; Kuehn, Stephen F.; Precit, Richard R.; Rogers, Michael S.

    1990-01-01

    Monitoring explosive devices is accomplished with a substantially z-cut lithium niobate crystal in abutment with the explosive device. Upon impact by a shock wave from detonation of the explosive device, the crystal emits a current pulse prior to destruction of the crystal. The current pulse is detected by a current viewing transformer and recorded as a function of time in nanoseconds. In order to self-check the crystal, the crystal has a chromium film resistor deposited thereon which may be heated by a current pulse prior to detonation. This generates a charge which is detected by a charge amplifier.

  3. Halo Star Lithium Depletion

    SciTech Connect

    Pinsonneault, M. H.; Walker, T. P.; Steigman, G.; Narayanan, Vijay K.

    1999-12-10

    The depletion of lithium during the pre-main-sequence and main-sequence phases of stellar evolution plays a crucial role in the comparison of the predictions of big bang nucleosynthesis with the abundances observed in halo stars. Previous work has indicated a wide range of possible depletion factors, ranging from minimal in standard (nonrotating) stellar models to as much as an order of magnitude in models that include rotational mixing. Recent progress in the study of the angular momentum evolution of low-mass stars permits the construction of theoretical models capable of reproducing the angular momentum evolution of low-mass open cluster stars. The distribution of initial angular momenta can be inferred from stellar rotation data in young open clusters. In this paper we report on the application of these models to the study of lithium depletion in main-sequence halo stars. A range of initial angular momenta produces a range of lithium depletion factors on the main sequence. Using the distribution of initial conditions inferred from young open clusters leads to a well-defined halo lithium plateau with modest scatter and a small population of outliers. The mass-dependent angular momentum loss law inferred from open cluster studies produces a nearly flat plateau, unlike previous models that exhibited a downward curvature for hotter temperatures in the 7Li-Teff plane. The overall depletion factor for the plateau stars is sensitive primarily to the solar initial angular momentum used in the calibration for the mixing diffusion coefficients. Uncertainties remain in the treatment of the internal angular momentum transport in the models, and the potential impact of these uncertainties on our results is discussed. The 6Li/7Li depletion ratio is also examined. We find that the dispersion in the plateau and the 6Li/7Li depletion ratio scale with the absolute 7Li depletion in the plateau, and we use observational data to set bounds on the 7Li depletion in main-sequence halo

  4. Method of recycling lithium borate to lithium borohydride through methyl borate

    DOEpatents

    Filby, Evan E.

    1977-01-01

    This invention provides a method for the recycling of lithium borate to lithium borohydride which can be reacted with water to generate hydrogen for utilization as a fuel. The lithium borate by-product of the hydrogen generation reaction is reacted with hydrogen chloride and water to produce boric acid and lithium chloride. The boric acid and lithium chloride are converted to lithium borohydride through a methyl borate intermediate to complete the recycle scheme.

  5. Study on High Speed Lithium Jet For Neutron Source of Boron Neutron Capture Therapy (BNCT)

    NASA Astrophysics Data System (ADS)

    Takahashi, Minoru; Kobayashi, Tooru; Zhang, Mingguang; Mák, Michael; Štefanica, Jirí; Dostál, Václav; Zhao, Wei

    The feasibility study of a liquid lithium type proton beam target was performed for the neutron source of the boron neutron capture therapy (BNCT). As the candidates of the liquid lithium target, a thin sheet jet and a thin film flow on a concave wall were chosen, and a lithium flow experiment was conducted to investigate the hydrodynamic stability of the targets. The surfaces of the jets and film flows with a thickness of 0.5 mm and a width of 50 mm were observed by means of photography. It has been found that a stable sheet jet and a stable film flow on a concave wall can be formed up to certain velocities by using a straight nozzle and a curved nozzle with the concave wall, respectively.

  6. Exploration of water jet generated by Q-switched laser induced water breakdown with different depths beneath a flat free surface.

    PubMed

    Chen, Ross C C; Yu, Y T; Su, K W; Chen, J F; Chen, Y F

    2013-01-14

    The dynamics of a water jet on a flat free surface are investigated using a nanosecond pulsed laser for creating an oscillating bubble with different depths beneath the free surface. A thin jet is shown to deform a crater surface resulted from surface depression and cause a circular ring-shaped crater on the connection surface between the crater of surface depression and the thin jet. The collapse of this circular ring-shaped crater is proposed to the crown-like formation around a thick jet. The evolution of the bubble depth suggests a classification of four distinctive ranges of the bubble depths: non-crown formation when the parameter of bubble depth over the maximum bubble radius γ ≤ 0.5, unstable crown formation when 0.5 ≤ γ ≤ 0.6, crown-like structure with a complete crown wall when 0.6 ≤ γ ≤ 1.1, and non-crown formation when 1.1 ≤ γ. Furthermore, the orientation of the crown wall gradually turns counterclockwise to vertical direction with increasing γ from 0.5 to 1.1, implying a high correlation between the orientation of the crown wall and the depth of the bubble. This correlation is explained and discussed by the directional change of the jet eruption from the collapse of circular ring-shaped crater. PMID:23388938

  7. Construction of wave-free potentials and multipoles in a two-layer fluid having free-surface boundary condition with higher-order derivatives

    NASA Astrophysics Data System (ADS)

    Das, Dilip

    2015-07-01

    There is a large class of problems in the field of fluid structure interaction where higher-order boundary conditions arise for a second-order partial differential equation. Various methods are being used to tackle these kind of mixed boundary-value problems associated with the Laplace's equation (or Helmholtz equation) arising in the study of waves propagating through solids or fluids. One of the widely used methods in wave structure interaction is the multipole expansion method. This expansion involves a general combination of a regular wave, a wave source, a wave dipole and a regular wave-free part. The wave-free part can be further expanded in terms of wave-free multipoles which are termed as wave-free potentials. These are singular solutions of Laplace's equation or two-dimensional Helmholz equation. Construction of these wave-free potentials and multipoles are presented here in a systematic manner for a number of situations such as two-dimensional non-oblique and oblique waves, three dimensional waves in two-layer fluid with free surface condition with higher order partial derivative are considered. In particular, these are obtained taking into account of the effect of the presence of surface tension at the free surface and also in the presence of an ice-cover modelled as a thin elastic plate. Also for limiting case, it can be shown that the multipoles and wave-free potential functions go over to the single layer multipoles and wave-free potential.

  8. The importance of mineral physics and a free surface in large-scale numerical models of mantle convection and plate tectonics

    NASA Astrophysics Data System (ADS)

    Tackley, Paul; Nakagawa, Takashi; Crameri, Fabio; Connolly, James; Deschamps, Frédéric; Kaus, Boris; Gerya, Taras

    2010-05-01

    Here, our recent progress in understanding the large-scale dynamics of the mantle convection - plate tectonics system is summarised, with particular focus on the influence of realistic mineral physics and a free surface. High pressure and temperature experiments and calculations of the properties of mantle minerals show that many different mineral phases exist as a function of pressure, temperature and composition [e.g. Irifune and Ringwood, EPSL 1987], and that these have a first-order influence on density (which has a large effect on the dynamics) and elastic moduli (which influence seismic velocity). Numerical models of global thermo-chemical mantle convection have typically used a simple approximation such as the extended Boussinesq approximation to treat these complex variations in material properties. Instead, we calculate composition-dependent mineral assemblages and their physical properties using the code Perple_X, which minimizes free energy for a given combination of oxides as a function of temperature and pressure [Connolly, EPSL 2005], and use this in a numerical model of thermo-chemical mantle convection in a three-dimensional spherical shell, to calculate three-dimensionally-varying physical proporties. In this presentation we compare the results obtained with this new, self-consistently-calculated treatment with results using our old, approximate treatment, focusing particularly on thermo-chemical-phase structures and seismic anomalies in the transition zone and core-mantle boundary (CMB) region [Nakagawa and Tackley, G3 2009], which are strongly influenced by the coupling between compositional variations and phase transitions. The numerical models treat the evolution of a planet over billions of years, including self-consistent plate tectonics arising from plastic yielding, melting-induced differentiation, and a parameterised model of core evolution based on heat extracted by mantle convection. Self-consistent plate tectonics-like behaviour may be

  9. A lithium superionic conductor.

    PubMed

    Kamaya, Noriaki; Homma, Kenji; Yamakawa, Yuichiro; Hirayama, Masaaki; Kanno, Ryoji; Yonemura, Masao; Kamiyama, Takashi; Kato, Yuki; Hama, Shigenori; Kawamoto, Koji; Mitsui, Akio

    2011-09-01

    Batteries are a key technology in modern society. They are used to power electric and hybrid electric vehicles and to store wind and solar energy in smart grids. Electrochemical devices with high energy and power densities can currently be powered only by batteries with organic liquid electrolytes. However, such batteries require relatively stringent safety precautions, making large-scale systems very complicated and expensive. The application of solid electrolytes is currently limited because they attain practically useful conductivities (10(-2) S cm(-1)) only at 50-80 °C, which is one order of magnitude lower than those of organic liquid electrolytes. Here, we report a lithium superionic conductor, Li(10)GeP(2)S(12) that has a new three-dimensional framework structure. It exhibits an extremely high lithium ionic conductivity of 12 mS cm(-1) at room temperature. This represents the highest conductivity achieved in a solid electrolyte, exceeding even those of liquid organic electrolytes. This new solid-state battery electrolyte has many advantages in terms of device fabrication (facile shaping, patterning and integration), stability (non-volatile), safety (non-explosive) and excellent electrochemical properties (high conductivity and wide potential window). PMID:21804556

  10. Plasma Response to Lithium-Coated Plasma-Facing Components in the National Spherical Torus Experiment

    SciTech Connect

    M.G. Bell, H.W. Kugel, R. Kaita, L.E. Zakharov, H. Schneider, B.P. LeBlanc, D. Mansfield, R.E. Bell, R. Maingi, S. Ding, S.M. Kaye, S.F. Paul, S.P. Gerhardt, J.M. Canik, J.C. Hosea, G. Taylor and the NSTX Research Team

    2009-08-20

    Experiments in the National Spherical Torus Experiment (NSTX) have shown beneficial effects on the performance of divertor plasmas as a result of applying lithium coatings on the graphite and carbonfiber- composite plasma-facing components. These coatings have mostly been applied by a pair of lithium evaporators mounted at the top of the vacuum vessel which inject collimated streams of lithium vapor towards the lower divertor. In NBI-heated, deuterium H-mode plasmas run immediately after the application of lithium, performance modifications included decreases in the plasma density, particularly in the edge, and inductive flux consumption, and increases in the electron and ion temperatures and the energy confinement time. Reductions in the number and amplitude of ELMs were observed, including complete ELM suppression for periods up to 1.2 s, apparently as a result of altering the stability of the edge. However, in the plasmas where ELMs were suppressed, there was a significant secular increase in the effective ion charge Zeff and the radiated power as a result of increases in the carbon and medium-Z metallic impurities, although not of lithium itself which remained at a very low level in the plasma core, <0.1%. The impurity buildup could be inhibited by repetitively triggering ELMs with the application of brief pulses of an n = 3 radial field perturbation. The reduction in the edge density by lithium also inhibited parasitic losses through the scrape-off layer of ICRF power coupled to the plasma, enabling the waves to heat electrons in the core of H-mode plasmas produced by NBI. Lithium has also been introduced by injecting a stream of chemically stabilized, fine lithium powder directly into the scrape-off layer of NBI-heated plasmas. The lithium was ionized in the SOL and appeared to flow along the magnetic field to the divertor plates. This method of coating produced similar effects to the evaporated lithium but at lower amounts.

  11. Lithium ion conducting ionic electrolytes

    DOEpatents

    Angell, C.A.; Xu, K.; Liu, C.

    1996-01-16

    A liquid, predominantly lithium-conducting, ionic electrolyte is described which has exceptionally high conductivity at temperatures of 100 C or lower, including room temperature. It comprises molten lithium salts or salt mixtures in which a small amount of an anionic polymer lithium salt is dissolved to stabilize the liquid against recrystallization. Further, a liquid ionic electrolyte which has been rubberized by addition of an extra proportion of anionic polymer, and which has good chemical and electrochemical stability, is described. This presents an attractive alternative to conventional salt-in-polymer electrolytes which are not cationic conductors. 4 figs.

  12. Lithium ion conducting ionic electrolytes

    DOEpatents

    Angell, C. Austen; Xu, Kang; Liu, Changle

    1996-01-01

    A liquid, predominantly lithium-conducting, ionic electrolyte is described which has exceptionally high conductivity at temperatures of 100.degree. C. or lower, including room temperature. It comprises molten lithium salts or salt mixtures in which a small amount of an anionic polymer lithium salt is dissolved to stabilize the liquid against recrystallization. Further, a liquid ionic electrolyte which has been rubberized by addition of an extra proportion of anionic polymer, and which has good chemical and electrochemical stability, is described. This presents an attractive alternative to conventional salt-in-polymer electrolytes which are not cationic conductors.

  13. Anodes for rechargeable lithium batteries

    DOEpatents

    Thackeray, Michael M.; Kepler, Keith D.; Vaughey, John T.

    2003-01-01

    A negative electrode (12) for a non-aqueous electrochemical cell (10) with an intermetallic host structure containing two or more elements selected from the metal elements and silicon, capable of accommodating lithium within its crystallographic host structure such that when the host structure is lithiated it transforms to a lithiated zinc-blende-type structure. Both active elements (alloying with lithium) and inactive elements (non-alloying with lithium) are disclosed. Electrochemical cells and batteries as well as methods of making the negative electrode are disclosed.

  14. Groundwater flow systems in mountainous terrain, 1. Numerical modeling technique

    NASA Astrophysics Data System (ADS)

    Forster, Craig; Smith, Leslie

    1988-07-01

    A coupled model of fluid flow and heat transfer is developed to characterize steady groundwater flow within a mountain massif. A coupled model is necessary because high-relief terrain can enhance groundwater flow to depths where elevated temperatures are encountered. A wide range in water table form and elevation expected in high-relief terrain is accommodated using a free-surface method. This approach allows us to examine the influence of thermal conditions on the patterns and rates of groundwater flow and the position of the water table. Vertical fluid flow is assumed to occur within the unsaturated zone to provide a simple basis for modeling advective heat transfer above the water table. This approach ensures that temperatures at the water table, and throughout the domain, are consistent with temperature conditions specified at the bedrock surface. Conventional free-surface methods provide poor estimates of the water table configuration in high-relief terrain. A modified free-surface approach is introduced to accommodate recharge at upper elevations on the seepage face, in addition to recharge at the free surface.

  15. A Lithium Superionic Sulfide Cathode for Lithium-Sulfur Batteries

    SciTech Connect

    Lin, Zhan; Liu, Zengcai; Dudney, Nancy J; Liang, Chengdu

    2013-01-01

    This work presents a facile synthesis approach for core-shell structured Li2S nanoparticles, which have Li2S as the core and Li3PS4 as the shell. This material functions as lithium superionic sulfide (LSS) cathode for long-lasting, energy-efficient lithium-sulfur (Li-S) batteries. The LSS has an ionic conductivity of 10-7 S cm-1 at 25 oC, which is 6 orders of magnitude higher than that of bulk Li2S (~10-13 S cm-1). The high lithium-ion conductivity of LSS imparts an excellent cycling performance to all-solid Li-S batteries, which also promises safe cycling of high-energy batteries with metallic lithium anodes.

  16. STREMR: Numerical model for depth-averaged incompressible flow

    NASA Astrophysics Data System (ADS)

    Roberts, Bernard

    1993-09-01

    The STREMR computer code is a two-dimensional model for depth-averaged incompressible flow. It accommodates irregular boundaries and nonuniform bathymetry, and it includes empirical corrections for turbulence and secondary flow. Although STREMR uses a rigid-lid surface approximation, the resulting pressure is equivalent to the displacement of a free surface. Thus, the code can be used to model free-surface flow wherever the local Froude number is 0.5 or less. STREMR uses a finite-volume scheme to discretize and solve the governing equations for primary flow, secondary flow, and turbulence energy and dissipation rate. The turbulence equations are taken from the standard k-Epsilon turbulence model, and the equation for secondary flow is developed herein. Appendices to this report summarize the principal equations, as well as the procedures used for their discrete solution.

  17. Cyanoethylated Compounds as Additives in Lithium/Lithium Ion Batteries

    SciTech Connect

    Nagasubramanian, Ganesan

    1998-05-08

    The power loss of lithium/lithium ion battery cells is significantly reduced, especially at low temperatures, when about 1% by weight of an additive is incorporated in the electrolyte layer of the cells. The usable additives are organic solvent soluble cyanoethylated polysaccharides and poly(vinyl alcohol). The power loss decrease results primarily from the decrease in the charge transfer resistance at the interface between the electrolyte and the cathode.

  18. Lithium metal doped electrodes for lithium-ion rechargeable chemistry

    DOEpatents

    Liu, Gao; Battaglia, Vince; Wang, Lei

    2016-09-13

    An embodiment of the invention combines the superior performance of a polyvinylidene difluoride (PVDF) or polyethyleneoxide (POE) binder, the strong binding force of a styrene-butadiene (SBR) binder, and a source of lithium ions in the form of solid lithium metal powder (SLMP) to form an electrode system that has improved performance as compared to PVDF/SBR binder based electrodes. This invention will provide a new way to achieve improved results at a much reduced cost.

  19. Cyanoethylated compounds as additives in lithium/lithium batteries

    DOEpatents

    Nagasubramanian, Ganesan

    1999-01-01

    The power loss of lithium/lithium ion battery cells is significantly reduced, especially at low temperatures, when about 1% by weight of an additive is incorporated in the electrolyte layer of the cells. The usable additives are organic solvent soluble cyanoethylated polysaccharides and poly(vinyl alcohol). The power loss decrease results primarily from the decrease in the charge transfer resistance at the interface between the electrolyte and the cathode.

  20. Silica Precipitation and Lithium Sorption

    SciTech Connect

    Jay Renew

    2015-09-20

    This file contains silica precipitation and lithium sorption data from the project. The silica removal data is corrected from the previous submission. The previous submission did not take into account the limit of detection of the ICP-MS procedure.