The influence of pore-fluid in the soil on ground vibrations from a tunnel embedded in a layered half-space

NASA Astrophysics Data System (ADS)

Yuan, Zonghao; Cao, Zhigang; Boström, Anders; Cai, Yuanqiang

2018-04-01

A computationally efficient semi-analytical solution for ground-borne vibrations from underground railways is proposed and used to investigate the influence of hydraulic boundary conditions at the scattering surfaces and the moving ground water table on ground vibrations. The arrangement of a dry soil layer with varying thickness resting on a saturated poroelastic half-space, which includes a circular tunnel subject to a harmonic load at the tunnel invert, creates the scenario of a moving water table for research purposes in this paper. The tunnel is modelled as a hollow cylinder, which is made of viscoelastic material and buried in the half-space below the ground water table. The wave field in the dry soil layer consists of up-going and down-going waves while the wave field in the tunnel wall consists of outgoing and regular cylindrical waves. The complete solution for the saturated half-space with a cylindrical hole is composed of down-going plane waves and outgoing cylindrical waves. By adopting traction-free boundary conditions on the ground surface and continuity conditions at the interfaces of the two soil layers and of the tunnel and the surrounding soil, a set of algebraic equations can be obtained and solved in the transformed domain. Numerical results show that the moving ground water table can cause an uncertainty of up to 20 dB for surface vibrations.

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

NASA Astrophysics Data System (ADS)

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

2001-01-01

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

One-step method for the production of nanofluids

DOEpatents

Kostic, Milivoje [Sycamore, IL; Golubovic, Mihajlo [Chicago, IL; Hull, John [Downers Grove, IL; Choi, Stephen U. S. [Naperville, IL

2011-08-16

A one step method and system for producing nanofluids by a nanoparticle-source evaporation and deposition of the evaporant into a base fluid. The base fluid such oil or ethylene glycol is placed in a rotating cylindrical drum having an adjustable heater-boat-evaporator and heat exchanger-cooler apparatus. As the drum rotates, a thin liquid layer is formed on the inside surface of the drum. An insulated heater-boat-evaporator having an evaporant material (nanoparticle-source) placed within its boat evaporator is adjustably positioned near a portion of the rotating thin liquid layer, the evaporant material being heated thereby evaporating a portion of the evaporant material and forming nanoparticles, the nanoparticles absorbed by the liquid film to form nanofluid.

Global structure transitions in an experimental induction furnace

NASA Astrophysics Data System (ADS)

Tasaka, Yuji; Galindo, Vladimir; Vogt, Tobias; Eckert, Sven

2017-11-01

Flows induced by alternating magnetic field (AMF) in a cylindrical vessel filled with liquid metal, alloy of GaInSn, were examined experimentally using ultrasonic Doppler velocimetry (UDV). Measurement lines of UDV arranged vertically set at different radial and azimuthal positions extracted flow structures and their time variations as spatio-temporal velocity maps in the opaque liquid metal layer. At low frequency of AMF, corresponding to shielding parameter S =μm σωR2 = O(1) (μm and σ are magnetic permeability and electric conductivity of the test fluid, ω angular frequency of AMF, and R the radius of cylindrical vessel), two toroidal vortices exist in the fluid layer as the large scale flow structure and have interactions each other. With increasing of S the structure has transition from toroidal vortex pair to four large scale circulations (S >= 100) via transient state, where strong interactions of two vortices are observed (30 < S < 100). Faster vertical stream is observed near the cylinder wall because of ski effect caused by AMF, and the time-averaged velocity of the stream takes maximum around S = 20 , which is little smaller value of S for the onset of the transient state. JSPS KAKENHI No. 15KK0219.

Motion through a non-homogeneous porous medium: Hydrodynamic permeability of a membrane composed of cylindrical particles

NASA Astrophysics Data System (ADS)

Yadav, Pramod Kumar

2018-01-01

The present problem is concerned with the flow of a viscous steady incompressible fluid through a non-homogeneous porous medium. Here, the non-homogeneous porous medium is a membrane built up by cylindrical particles. The flow outside the membrane is governed by the Stokes equation and the flow through the non-homogeneous porous membrane composed by cylindrical particles is governed by Darcy's law. In this work, we discussed the effect of various fluid parameters like permeability parameter k0, discontinuity coefficient at fluid-non homogeneous porous interface, viscosity ratio of viscous incompressible fluid region and non-homogeneous porous region, etc. on hydrodynamic permeability of a membrane, stress and on velocity profile. The comparative study for hydrodynamic permeability of membrane built up by non-homogeneous porous cylindrical particles and porous cylindrical shell enclosing a cylindrical cavity has been studied. The effects of various fluid parameters on the streamlines flow patterns are also discussed.

Fluid-membrane tethers: minimal surfaces and elastic boundary layers.

PubMed

Powers, Thomas R; Huber, Greg; Goldstein, Raymond E

2002-04-01

Thin cylindrical tethers are common lipid bilayer membrane structures, arising in situations ranging from micromanipulation experiments on artificial vesicles to the dynamic structure of the Golgi apparatus. We study the shape and formation of a tether in terms of the classical soap-film problem, which is applied to the case of a membrane disk under tension subject to a point force. A tether forms from the elastic boundary layer near the point of application of the force, for sufficiently large displacement. Analytic results for various aspects of the membrane shape are given.

The AGCE related studies of baroclinic flows in spherical geometry

NASA Technical Reports Server (NTRS)

Hyun, J. M.

1983-01-01

Steady state, axisymmetric motions of a Boussineaq fluid continued in rotating spherical anmulus are considered. The motions are driven by latitudinally varying temperature gradient at the shells. Linearized formulations for a narrow gap are derived and the flow field is divided into the Ekman layers and the geostrophic interior. The Ekman layer flows are consistent with the known results for cylindrical geometries. Within the framework of rather restrictive assumptions, the interior flows are solved by a series of associated Legendre polynomials. The solutions show qualitative features valid at midlatitudes.

QUAGMIRE v1.3: a quasi-geostrophic model for investigating rotating fluids experiments

NASA Astrophysics Data System (ADS)

Williams, P. D.; Haine, T. W. N.; Read, P. L.; Lewis, S. R.; Yamazaki, Y. H.

2008-09-01

QUAGMIRE is a quasi-geostrophic numerical model for performing fast, high-resolution simulations of multi-layer rotating annulus laboratory experiments on a desktop personal computer. The model uses a hybrid finite-difference/spectral approach to numerically integrate the coupled nonlinear partial differential equations of motion in cylindrical geometry in each layer. Version 1.3 implements the special case of two fluid layers of equal resting depths. The flow is forced either by a differentially rotating lid, or by relaxation to specified streamfunction or potential vorticity fields, or both. Dissipation is achieved through Ekman layer pumping and suction at the horizontal boundaries, including the internal interface. The effects of weak interfacial tension are included, as well as the linear topographic beta-effect and the quadratic centripetal beta-effect. Stochastic forcing may optionally be activated, to represent approximately the effects of random unresolved features. A leapfrog time stepping scheme is used, with a Robert filter. Flows simulated by the model agree well with those observed in the corresponding laboratory experiments.

QUAGMIRE v1.3: a quasi-geostrophic model for investigating rotating fluids experiments

NASA Astrophysics Data System (ADS)

Williams, P. D.; Haine, T. W. N.; Read, P. L.; Lewis, S. R.; Yamazaki, Y. H.

2009-02-01

QUAGMIRE is a quasi-geostrophic numerical model for performing fast, high-resolution simulations of multi-layer rotating annulus laboratory experiments on a desktop personal computer. The model uses a hybrid finite-difference/spectral approach to numerically integrate the coupled nonlinear partial differential equations of motion in cylindrical geometry in each layer. Version 1.3 implements the special case of two fluid layers of equal resting depths. The flow is forced either by a differentially rotating lid, or by relaxation to specified streamfunction or potential vorticity fields, or both. Dissipation is achieved through Ekman layer pumping and suction at the horizontal boundaries, including the internal interface. The effects of weak interfacial tension are included, as well as the linear topographic beta-effect and the quadratic centripetal beta-effect. Stochastic forcing may optionally be activated, to represent approximately the effects of random unresolved features. A leapfrog time stepping scheme is used, with a Robert filter. Flows simulated by the model agree well with those observed in the corresponding laboratory experiments.

Theoretical and experimental design studies for the Atmospheric General Circulation Experiment

NASA Technical Reports Server (NTRS)

Fowlis, W. W.; Hathaway, D. H.; Miller, T. L.; Roberts, G. O.; Kopecky, K. J.

1985-01-01

The major criterion for the Atmospheric General Circulation Experiment (AGCE) design is that it be possible to realize strong baroclinic instability in the spherical configuration chosen. A configuration was selected in which a hemispherical shell of fluid is subjected to latitudinal temperature gradients on its spherical boundaries and the latitudinal boundaries are insulators. Work in the laboratory with a cylindrical version of this configuration revealed more instabilities than baroclinic instability. Since researchers fully expect these additional instabilities to appear in the spherical configuration also, they decided to continue the laboratory cylindrical annulus studies. Four flow regimes were identified: an axisymmetric Hadley circulation, boundary layer convection, baroclinic waves and deep thermal convection. Regime diagrams were prepared.

Hydrodynamic water impact. [Apollo spacecraft waterlanding

NASA Technical Reports Server (NTRS)

Kettleborough, C. F.

1972-01-01

The hydrodynamic impact of a falling body upon a viscous incompressible fluid was investigated by numerically solving the equations of motion. Initially the mathematical model simulated the axisymmetric impact of a rigid right circular cylinder upon the initially quiescent free surface of a fluid. A compressible air layer exists between the falling cylinder and the liquid free surface. The mathematical model was developed by applying the Navier-Stokes equations to the incompressible air layer and the incompressible fluid. Assuming the flow to be one dimensional within the air layer, the average velocity, pressure and density distributions were calculated. The liquid free surface was allowed to deform as the air pressure acting on it increases. For the liquid the normalized equations were expressed in two-dimensional cylindrical coordinates. The governing equations for the air layer and the liquid were expressed in finite difference form and solved numerically. For the liquid a modified version of the Marker-and-Cell method was used. The mathematical model has been reexamined and a new approach has recently been initiated. Essentially this consists of examining the impact of an inclined plate onto a quiesent water surface with the equations now formulated in cartesian coordinates.

Sound Transmission through Cylindrical Shell Structures Excited by Boundary Layer Pressure Fluctuations

NASA Technical Reports Server (NTRS)

Tang, Yvette Y.; Silcox, Richard J.; Robinson, Jay H.

1996-01-01

This paper examines sound transmission into two concentric cylindrical sandwich shells subject to turbulent flow on the exterior surface of the outer shell. The interior of the shells is filled with fluid medium and there is an airgap between the shells in the annular space. The description of the pressure field is based on the cross-spectral density formulation of Corcos, Maestrello, and Efimtsov models of the turbulent boundary layer. The classical thin shell theory and the first-order shear deformation theory are applied for the inner and outer shells, respectively. Modal expansion and the Galerkin approach are used to obtain closed-form solutions for the shell displacements and the radiation and transmission pressures in the cavities including both the annular space and the interior. The average spectral density of the structural responses and the transmitted interior pressures are expressed explicitly in terms of the summation of the cross-spectral density of generalized force induced by the boundary layer turbulence. The effects of acoustic and hydrodynamic coincidences on the spectral density are observed. Numerical examples are presented to illustrate the method for both subsonic and supersonic flows.

­­Clastic Pipes on Mars: Evidence for a Near Surface Groundwater System

NASA Astrophysics Data System (ADS)

Wheatley, D. F.; Chan, M. A.; Okubo, C. H.

2017-12-01

Clastic pipes, a type of vertical, columnar injectite, occur throughout the terrestrial stratigraphic record and are identified across many Martian terrains. Terrestrial pipe analogs can aid in identifying clastic pipes on Mars to understand their formation processes and their implications for a past near-surface groundwater system. On Earth, clastic pipes form through fluidization of overpressurized sediment. Fluidization occurs when the upward frictional (i.e., drag) forces of escaping fluids overpower the downward acting gravitational force. To create the forces necessary for pipe formation requires overpressurization of a body of water-saturated porous media overlain by a low permeability confining layer. As the pressure builds, the confining layer eventually fractures and the escaping fluids fluidize the porous sediment causing the sediment to behave like a fluid. These specific formation conditions record evidence of a violent release of fluid-suspended sediment including brecciation of the host and sealing material, internal outward grading/sorting that results in a coarser-grained commonly better cemented outer rind, traction structures, and a cylindrical geometry. Pipes form self-organized, dispersed spatial relationships due to the efficient diffusion of overpressured zones in the subsurface and the expulsion of sediment under pressure. Martian pipes occur across the northern lowlands, dichotomy boundary, and southern highlands in various forms of erosional relief ranging from newer eruption structures to eroded cylindrical/conical mounds with raised rims to highly eroded mounds/hills. Similar to terrestrial examples, Martian pipes form in evenly-spaced, self-organized arrangements. The pipes are typically internally massive with a raised outer rim (interpreted as a sorted, coarser-grained, better-cemented rim). This evidence indicates that Martian pipes formed through fluidization, which requires a near-surface groundwater system. Pipes create a window into the subsurface by excavating subsurface sediment and waters. After emplacement, pipes can also act as fluid conduits, channeling post-depositional fluid flow. The preferential porosity and flow paths may make the pipes an ideal exploration target for microbial life.

Linear tearing mode stability equations for a low collisionality toroidal plasma

NASA Astrophysics Data System (ADS)

Connor, J. W.; Hastie, R. J.; Helander, P.

2009-01-01

Tearing mode stability is normally analysed using MHD or two-fluid Braginskii plasma models. However for present, or future, large hot tokamaks like JET or ITER the collisionality is such as to place them in the banana regime. Here we develop a linear stability theory for the resonant layer physics appropriate to such a regime. The outcome is a set of 'fluid' equations whose coefficients encapsulate all neoclassical physics: the neoclassical Ohm's law, enhanced ion inertia, cross-field transport of particles, heat and momentum all play a role. While earlier treatments have also addressed this type of neoclassical physics we differ in incorporating the more physically relevant 'semi-collisional fluid' regime previously considered in cylindrical geometry; semi-collisional effects tend to screen the resonant surface from the perturbed magnetic field, preventing reconnection. Furthermore we also include thermal physics, which may modify the results. While this electron description is of wide relevance and validity, the fluid treatment of the ions requires the ion banana orbit width to be less than the semi-collisional electron layer. This limits the application of the present theory to low magnetic shear—however, this is highly relevant to the sawtooth instability—or to colder ions. The outcome of the calculation is a set of one-dimensional radial differential equations of rather high order. However, various simplifications that reduce the computational task of solving these are discussed. In the collisional regime, when the set reduces to a single second-order differential equation, the theory extends previous work by Hahm et al (1988 Phys. Fluids 31 3709) to include diamagnetic-type effects arising from plasma gradients, both in Ohm's law and the ion inertia term of the vorticity equation. The more relevant semi-collisional regime pertaining to JET or ITER, is described by a pair of second-order differential equations, extending the cylindrical equations of Drake et al (1983 Phys. Fluids 26 2509) to toroidal geometry.

Sloshing instability and electrolyte layer rupture in liquid metal batteries

NASA Astrophysics Data System (ADS)

Weber, Norbert; Beckstein, Pascal; Herreman, Wietze; Horstmann, Gerrit Maik; Nore, Caroline; Stefani, Frank; Weier, Tom

2017-05-01

Liquid metal batteries (LMBs) are discussed today as a cheap grid scale energy storage, as required for the deployment of fluctuating renewable energies. Built as stable density stratification of two liquid metals separated by a thin molten salt layer, LMBs are susceptible to short-circuit by fluid flows. Using direct numerical simulation, we study a sloshing long wave interface instability in cylindrical cells, which is already known from aluminium reduction cells. After characterising the instability mechanism, we investigate the influence of cell current, layer thickness, density, viscosity, conductivity and magnetic background field. Finally we study the shape of the interface and give a dimensionless parameter for the onset of sloshing as well as for the short-circuit.

Instabilities of conducting fluid flows in cylindrical shells under external forcing

NASA Astrophysics Data System (ADS)

Burguete, Javier; Miranda, Montserrat

2010-11-01

Flows created in neutral conducting flows remain one of the less studied topics of fluid dynamics, in spite of their relevance both in fundamental research (dynamo action, turbulence suppression) and applications (continuous casting, aluminium production, biophysics). Here we present the effect of a time-dependent magnetic field parallel to the axis of circular cavities. Due to the Lenz's law, the time-dependent magnetic field generates an azymuthal current, that produces a radial force. This force produces the destabilization of the static fluid layer, and a flow is created. The geommetry of the experimental cell is a disc layer with external diameter smaller than 94 mm, with or without internal hole. The layer is up to 20mm depth, and we use as conducting fluid an In-Ga-Sn alloy. There is no external current applied on the problem, only an external magnetic field. This field evolves harmonically with a frequency up to 10Hz, small enough to not to observe skin depth effects. The magnitude ranges from 0 to 0.1 T. With a threshold of 0.01T a dynamical behaviour is observed, and the main characteristics of this flow have been determined: different temporal resonances and spatial patterns with differents symmetries (squares, hexagonal, triangles,...).

QUAGMIRE v1.3: a quasi-geostrophic model for investigating rotating fluids experiments

NASA Astrophysics Data System (ADS)

Williams, P. D.; Haine, T. W. N.; Read, P. L.; Lewis, S. R.; Yamazaki, Y. H.

2009-04-01

The QUAGMIRE model has recently been made freely available for public use. QUAGMIRE is a quasi-geostrophic numerical model for performing fast, high-resolution simulations of multi-layer rotating annulus laboratory experiments on a desktop personal computer. This presentation describes the model's main features. QUAGMIRE uses a hybrid finite-difference/spectral approach to numerically integrate the coupled nonlinear partial differential equations of motion in cylindrical geometry in each layer. Version 1.3 implements the special case of two fluid layers of equal resting depths. The flow is forced either by a differentially rotating lid, or by relaxation to specified streamfunction or potential vorticity fields, or both. Dissipation is achieved through Ekman layer pumping and suction at the horizontal boundaries, including the internal interface. The effects of weak interfacial tension are included, as well as the linear topographic beta-effect and the quadratic centripetal beta-effect. Stochastic forcing may optionally be activated, to represent approximately the effects of random unresolved features. A leapfrog time stepping scheme is used, with a Robert filter. Flows simulated by the model agree well with those observed in the corresponding laboratory experiments.

A numerical study of natural convection in a vertical annulus filled with gallium in the presence of magnetic field

NASA Astrophysics Data System (ADS)

Afrand, Masoud; Toghraie, Davood; Karimipour, Arash; Wongwises, Somchai

2017-05-01

Presets work aims to investigate the natural convection inside a cylindrical annulus mold containing molten gallium under a horizontal magnetic field in three-dimensional coordinates. The modeling system is a vertical cylindrical annulus which is made by two co-axial cylinders of internal and external radii. The internal and external walls are maintained isothermal but in different temperatures. The upper and lower sides of annulus are also considered adiabatic while it is filled by an electrical conducting fluid. Three dimensional cylindrical coordinates as (r , θ , z) are used to respond the velocity components as (u , v , w) . The governing equations are steady, laminar and Newtonian using the Boussinesq approximation. Equations are nonlinear and they must be corresponded by applying the finite volume approach; so that the hybrid-scheme is applied to discretize equations. The results imply that magnetic field existence leads to generate the Lorentz force in opposite direction of the buoyancy forces. Moreover the Lorentz force and its corresponded electric field are more significant in both Hartmann layer and Roberts layer, respectively. The strong magnetic field is required to achieve better quality products in the casting process of a liquid metal with a higher Prandtl number.

Nature of fluid flows in differentially heated cylindrical container filled with a stratified solution

NASA Technical Reports Server (NTRS)

Wang, Jai-Ching

1992-01-01

Semiconductor crystals such as Hg(1-x)Cd(x)Te grown by unidirectional solidification Bridgmann method have shown compositional segregations in both the axial and radial directions. Due to the wide separation between the liquidus and the solidus of its pseudobinary phase diagram, there is a diffusion layer of higher HgTe content built up in the melt near the melt-solid interface which gives a solute concentration gradient in the axial direction. Because of the higher thermal conductivity in the melt than that in the crystal there is a thermal leakage through the fused silica crucible wall near the melt-solid interface. This gives a thermal gradient in the radial direction. Hart (1971), Thorpe, Hutt and Soulsby (1969) have shown that under such condition a fluid will become convectively unstable as a result of different diffusivities of temperature and solute. It is quite important to understand the effects of this thermosolute convection on the compositional segregation in the unidirectionally solidified crystals. To reach this goal, we start with a simplified problem. We study the nature of fluid flows of a stratified solution in a cylindrical container with a radial temperature gradient. The cylindrical container wall is considered to be maintained at a higher temperature than that at the center of the solution and the solution in the lower gravitational direction has higher solute concentration which decrease linearly to a lower concentration and then remain constant to the top of the solution. The sample solution is taken to be salt water.

Hypersonic Magneto-Fluid-Dynamic Compression in Cylindrical Inlet

NASA Technical Reports Server (NTRS)

Shang, Joseph S.; Chang, Chau-Lyan

2007-01-01

Hypersonic magneto-fluid-dynamic interaction has been successfully performed as a virtual leading-edge strake and a virtual cowl of a cylindrical inlet. In a side-by-side experimental and computational study, the magnitude of the induced compression was found to be depended on configuration and electrode placement. To better understand the interacting phenomenon the present investigation is focused on a direct current discharge at the leading edge of a cylindrical inlet for which validating experimental data is available. The present computational result is obtained by solving the magneto-fluid-dynamics equations at the low magnetic Reynolds number limit and using a nonequilibrium weakly ionized gas model based on the drift-diffusion theory. The numerical simulation provides a detailed description of the intriguing physics. After validation with experimental measurements, the computed results further quantify the effectiveness of a magnet-fluid-dynamic compression for a hypersonic cylindrical inlet. At a minuscule power input to a direct current surface discharge of 8.14 watts per square centimeter of electrode area produces an additional compression of 6.7 percent for a constant cross-section cylindrical inlet.

Soft lubrication

NASA Astrophysics Data System (ADS)

Skotheim, Jan; Mahadevan, Laksminarayanan

2004-11-01

We study the lubrication of fluid-immersed soft interfaces and show that elastic deformation couples tangential and normal forces and thus generates lift. We consider materials that deform easily, due to either geometry (e.g a shell) or constitutive properties (e.g. a gel or a rubber), so that the effects of pressure and temperature on the fluid properties may be neglected. Four different system geometries are considered: a rigid cylinder moving tangentially to a soft layer coating a rigid substrate; a soft cylinder moving tangentially to a rigid substrate; a cylindrical shell moving tangentially to a rigid substrate; and finally a journal bearing coated with a thin soft layer, which being a conforming contact allows us to gauge the influence of contact geometry. In addition, for the particular case of a soft layer coating a rigid substrate we consider both elastic and poroelastic material responses. Finally, we consider the role of contact geometry in the context of the journal bearing, a conforming contact. For all these cases we find the same generic behavior: there is an optimal combination of geometric and material parameters that maximizes the dimensionless normal force as a function of the softness.

Heat Transfer and Fluid Mechanics Institute, Meeting, 25th, University of California, Davis, Calif., June 21-23, 1976, Proceedings

NASA Technical Reports Server (NTRS)

Mckillop, A. A.; Baughn, J. W.; Dwyer, H. A.

1976-01-01

Major research advances in heat transfer and fluid dynamics are outlined, with particular reference to relevant energy problems. Of significant importance are such topics as synthetic fuels in combustion, turbulence models, combustion modeling, numerical methods for interacting boundary layers, and light-scattering diagnostics for gases. The discussion covers thermal convection, two-phase flow and boiling heat transfer, turbulent flows, combustion, and aerospace heat transfer problems. Other areas discussed include compressible flows, fluid mechanics and drag, and heat exchangers. Featured topics comprise heat and salt transfer in double-diffusive systems, limits of boiling heat transfer in a liquid-filled enclosure, investigation of buoyancy-induced flow stratification in a cylindrical plenum, and digital algorithms for dynamic analysis of a heat exchanger. Individual items are announced in this issue.

Transitional boundary layer in low-Prandtl-number convection at high Rayleigh number

NASA Astrophysics Data System (ADS)

Schumacher, Joerg; Bandaru, Vinodh; Pandey, Ambrish; Scheel, Janet

2016-11-01

The boundary layer structure of the velocity and temperature fields in turbulent Rayleigh-Bénard flows in closed cylindrical cells of unit aspect ratio is revisited from a transitional and turbulent viscous boundary layer perspective. When the Rayleigh number is large enough the boundary layer dynamics at the bottom and top plates can be separated into an impact region of downwelling plumes, an ejection region of upwelling plumes and an interior region (away from side walls) that is dominated by a shear flow of varying orientation. This interior plate region is compared here to classical wall-bounded shear flows. The working fluid is liquid mercury or liquid gallium at a Prandtl number of Pr = 0 . 021 for a range of Rayleigh numbers of 3 ×105 <= Ra <= 4 ×108 . The momentum transfer response to these system parameters generates a fluid flow in the closed cell with a macroscopic flow Reynolds number that takes values in the range of 1 . 8 ×103 <= Re <= 4 . 6 ×104 . It is shown that particularly the viscous boundary layers for the largest Ra are highly transitional and obey some properties that are directly comparable to transitional channel flows at friction Reynolds numbers below 100. This work is supported by the Deutsche Forschungsgemeinschaft.

Nonlinear excitations in electron-positron-ion plasmas in accretion disks of active galactic nuclei

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

Moslem, W. M.; Kourakis, I.; Shukla, P. K.

2007-10-15

The propagation of acoustic nonlinear excitations in an electron-positron-ion (e-p-i) plasma composed of warm electrons and positrons, as well as hot ions, has been investigated by adopting a two-dimensional cylindrical geometry. The electrons and positrons are modeled by hydrodynamic fluid equations, while the ions are assumed to follow a temperature-parametrized Boltzmann distribution (the fixed ion model is recovered in the appropriate limit). This situation applies in the accretion disk near a black hole in active galactic nuclei, where the ion temperature may be as high as 3 to 300 times that of the electrons. Using a reductive perturbation technique, amore » cylindrical Kadomtsev-Petviashvili equation is derived and its exact soliton solutions are presented. Furthermore, real situations in which the strength of the nonlinearity may be weak are considered, so that higher-order nonlinearity plays an important role. Accordingly, an extended cylindrical Kadomtsev-Petviashvili equation is derived, which admits both soliton and double-layer solutions. The characteristics of the nonlinear excitations obtained are investigated in detail.« less

Acoustic scattering reduction using layers of elastic materials

NASA Astrophysics Data System (ADS)

Dutrion, Cécile; Simon, Frank

2017-02-01

Making an object invisible to acoustic waves could prove useful for military applications or measurements in confined space. Different passive methods have been proposed in recent years to avoid acoustic scattering from rigid obstacles. These techniques are exclusively based on acoustic phenomena, and use for instance multiple resonators or scatterers. This paper examines the possibility of designing an acoustic cloak using a bi-layer elastic cylindrical shell to eliminate the acoustic field scattered from a rigid cylinder hit by plane waves. This field depends on the dimensional and mechanical characteristics of the elastic layers. It is computed by a semi-analytical code modelling the vibrations of the coating under plane wave excitation. Optimization by genetic algorithm is performed to determine the characteristics of a bi-layer material minimizing the scattering. Considering an external fluid consisting of air, realistic configurations of elastic coatings emerge, composed of a thick internal orthotopic layer and a thin external isotropic layer. These coatings are shown to enable scattering reduction at a precise frequency or over a larger frequency band.

Triboelectric nanogenerator

DOEpatents

Wang, Zhong Lin; Zhu, Guang; Jing, Quingshen

2017-01-10

A generator includes a first cylindrical member and a second cylindrical member. The first cylindrical member includes a first dielectric layer including a first material that has a first rating on a triboelectric series; and a first conductive strip disposed around an exterior surfaces of the first cylindrical member. The first conductive strip includes a second material that has a second rating on the triboelectric series that is different from the first rating. The second cylindrical member is disposed about the first cylindrical member and includes a second dielectric layer that includes the first material. The second cylindrical member also includes the second material and at least one second conductive strip disposed around an interior surface of the second cylindrical member. A sliding mechanism causes lateral relative motion between the first cylindrical member against the second cylindrical member, generating an electric potential imbalance between the first and second conductive strip.

Dynamic transverse shear modulus for a heterogeneous fluid-filled porous solid containing cylindrical inclusions

NASA Astrophysics Data System (ADS)

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

2016-09-01

An exact analytical solution is presented for the effective dynamic transverse shear modulus in a heterogeneous fluid-filled porous solid containing cylindrical inclusions. The complex and frequency-dependent properties of the dynamic shear modulus are caused by the physical mechanism of mesoscopic-scale wave-induced fluid flow whose scale is smaller than wavelength but larger than the size of pores. Our model consists of three phases: a long cylindrical inclusion, a cylindrical shell of poroelastic matrix material with different mechanical and/or hydraulic properties than the inclusion and an outer region of effective homogeneous medium of laterally infinite extent. The behavior of both the inclusion and the matrix is described by Biot's consolidation equations, whereas the surrounding effective medium which is used to describe the effective transverse shear properties of the inner poroelastic composite is assumed to be a viscoelastic solid whose complex transverse shear modulus needs to be determined. The determined effective transverse shear modulus is used to quantify the S-wave attenuation and velocity dispersion in heterogeneous fluid-filled poroelastic rocks. The calculation shows the relaxation frequency and relative position of various fluid saturation dispersion curves predicted by this study exhibit very good agreement with those of a previous 2-D finite-element simulation. For the double-porosity model (inclusions having a different solid frame than the matrix but the same pore fluid as the matrix) the effective shear modulus also exhibits a size-dependent characteristic that the relaxation frequency moves to lower frequencies by two orders of magnitude if the radius of the cylindrical poroelastic composite increases by one order of magnitude. For the patchy-saturation model (inclusions having the same solid frame as the matrix but with a different pore fluid from the matrix), the heterogeneity in pore fluid cannot cause any attenuation in the transverse shear modulus at all. A comparison with the case of spherical inclusions illustrates that the transverse shear modulus for the cylindrical inclusion exhibits more S-wave attenuation than spherical inclusions.

Data on the mixing of non-Newtonian fluids by a Rushton turbine in a cylindrical tank.

PubMed

Khapre, Akhilesh; Munshi, Basudeb

2016-09-01

The paper focuses on the data collected from the mixing of shear thinning non-Newtonian fluids in a cylindrical tank by a Rushton turbine. The data presented are obtained by using Computational Fluid Dynamics (CFD) simulation of fluid flow field in the entire tank volume. The CFD validation data for this study is reported in the research article 'Numerical investigation of hydrodynamic behavior of shear thinning fluids in stirred tank' (Khapre and Munshi, 2015) [1]. The tracer injection method is used for the prediction of mixing time and mixing efficiency of a Rushton turbine impeller.

Sound Transmission through a Cylindrical Sandwich Shell with Honeycomb Core

NASA Technical Reports Server (NTRS)

Tang, Yvette Y.; Robinson, Jay H.; Silcox, Richard J.

1996-01-01

Sound transmission through an infinite cylindrical sandwich shell is studied in the context of the transmission of airborne sound into aircraft interiors. The cylindrical shell is immersed in fluid media and excited by an oblique incident plane sound wave. The internal and external fluids are different and there is uniform airflow in the external fluid medium. An explicit expression of transmission loss is derived in terms of modal impedance of the fluids and the shell. The results show the effects of (a) the incident angles of the plane wave; (b) the flight conditions of Mach number and altitude of the aircraft; (c) the ratios between the core thickness and the total thickness of the shell; and (d) the structural loss factors on the transmission loss. Comparisons of the transmission loss are made among different shell constructions and different shell theories.

Transient natural and surface-tension-driven convection in a two-layer gas-and-liquid enclosure with nonuniform radiative transfer

NASA Technical Reports Server (NTRS)

Abramzon, B.; Edwards, D. K.; Sirignano, W. A.

1986-01-01

A numerical study has been made of transient heat transfer and fluid flow in a cylindrical enclosure containing a two-layer gas-and-liquid system. The geometric configuration and the boundary conditions of the problem are relevant to the analysis of the preignition processes during the fire accident situation involving a pool of liquid fuel in the vicinity of an ignition source. It is demonstrated that the effects of the natural and thermocapillary convection, radiative transfer, thermal inertia and conduction of the walls bounding the enclosure, as well as, the magnitude of the gravity field play important roles in the development of the temperature and velocity fields in the container.

Anisotropic metamaterial waveguide driven by a cold and relativistic electron beam

NASA Astrophysics Data System (ADS)

Torabi, Mahmoud; Shokri, Babak

2018-03-01

We study the interaction of a cold and relativistic electron beam with a cylindrical waveguide loaded by an anisotropic and dispersive metamaterial layer. The general dispersion relation for the transverse magnetic (TM) mode, through the linear fluid model and Maxwell equations decomposition method, is derived. The effects of some metamaterial parameters on dispersion relation are presented. A qualitative discussion shows the possibility of monomodal propagation band widening and obtaining more control on dispersion relation behavior. Especially for epsilon negative near zero metamaterials, these effects are considerable. Finally, the anisotropy and metamaterial layer thickness impacts on wave growth rate for different metamaterials are considered. The results demonstrate that we can control both wave growth rate and voltage of saturation peak by metamaterial parameters.

Acoustic guided waves in cylindrical solid-fluid structures: Modeling with a sweeping frequency finite element method and experimental validation

NASA Astrophysics Data System (ADS)

Liu, Yang; D'Angelo, Ralph M.; Sinha, Bikash K.; Zeroug, Smaine

2017-02-01

Modeling and understanding the complex elastic-wave physics prevalent in solid-fluid cylindrically-layered structures is of importance in many NDE fields, and most pertinently in the domain of well integrity evaluation of cased holes in the oil and gas industry. Current sonic measurements provide viable techniques for well integrity evaluation yet their practical effectiveness is hampered by the current lack of knowledge of acoustic wave fields particularly in complicated cased-hole geometry where for instance two or more nested steel strings are present in the borehole. In this article, we propose and implement a Sweeping Frequency Finite Element Method (SFFEM) for acoustic guided waves simulation in complex geometries that include double steel strings cemented to each other and to the formation and where the strings may be non-concentric. Transient dynamic finite element models are constructed with sweeping frequency signals being applied as the excitation sources. The sources and receivers disposition simulate current sonic measurement tools deployed in the oilfield. Synthetic wavetrains are recorded and processed with modified matrix pencil method to isolate both the dispersive and non-dispersive propagating guided wave modes. Scaled experiments of fluid-filled double strings with dimensions mimicking the real ones encountered in the field have also been carried out to generate reference data. A comparison of the experimental and numerical results indicates that the SFFEM is capable of accurately reproducing the rich and intricate higher-order multiple wave fields observed experimentally in the fluid-filled double string geometries.

A computational analysis subject to thermophysical aspects of Sisko fluid flow over a cylindrical surface

NASA Astrophysics Data System (ADS)

Awais, M.; Khalil-Ur-Rehman; Malik, M. Y.; Hussain, Arif; Salahuddin, T.

2017-09-01

The present analysis is devoted to probing the salient features of the mixed convection and non-linear thermal radiation effects on non-Newtonian Sisko fluid flow over a linearly stretching cylindrical surface. Properties of heat transfer are outlined via variable thermal conductivity and convective boundary conditions. The boundary layer approach is implemented to construct the mathematical model in the form of partial differential equations. Then, the requisite PDEs are transmuted into a complex ordinary differential system by invoking appropriate dimensionless variables. Solution of subsequent ODEs is obtained by utilizing the Runge-Kutta algorithm (fifth order) along with the shooting scheme. The graphical illustrations are presented to interpret the features of the involved pertinent flow parameters on concerning profiles. For a better description of the fluid flow, numerical variations in local skin friction coefficient and local Nusselt number are scrutinized in tables. From thorough analysis, it is inferred that the mixed convection parameter and the curvature parameter increase the velocity while temperature shows a different behavior. Additionally, both momentum and thermal distribution of fluid flow decrease with increasing values of the non-linearity index. Furthermore, variable thermal parameter and heat generation/absorption parameter amplify the temperature significantly. The skin friction is an increasing function of all momentum controlling parameters. The local Nusselt number also shows a similar behavior against heat radiation parameter and variable thermal conductivity parameter while it shows a dual nature for the heat generation/absorption parameter. Finally, the obtained results are validated by comparison with the existing literature and hence the correctness of the analysis is proved.

DEVICE FOR CHARGING OR DISCHARGING

DOEpatents

Untemeyer, S.; Hutter, E.

1959-01-13

A loading and unloading device is presented for loading objects into and unloading them from an apparatus in which fluid under pressure is employed, such as a heterogeneous rcactor wherein the fuel elements are in the form of slugs. This device is comprised essentially of a cylindrical member disposed coaxially with and as an accessible extension of an internal tube member of the apparatus in which the objects, or fuel elements, are normally disposed in use. The outermost end of the cylindrical extension is closed by a removable seal plug. The lower end of the cylindrical extension is separated from the intennal tube by a disk valve which is operated externally. A source of pressure fluid and a drain line are provided in communication with the interior of the cylindrical extension. To load an object into the internal tube, the disk valve is closed, the seal plug is renmoved, an object is placed in the cylindrical extension, and the seal plug is replaced. The disk valve is then opened and ihe pressure of the fluid within the cylindrical extension is increased until it is greater than the pressure within the internal tube and forces the object out of the cylindrical extension into the internal tube. To remove an object from the tube the disk valve is opened and the intenior of thc cylindnical extension is connected to the drain line whereby the operating pressure within the intennal tube forces the object out of the internal tube and up into the cylindrical extension. The disk valve is then closed and the seal plug is removed to permit removal of the object.

Cylindrical acoustic levitator/concentrator having non-circular cross-section

DOEpatents

Kaduchak, Gregory; Sinha, Dipen N.

2003-11-11

A low-power, inexpensive acoustic apparatus for levitation and/or concentration of aerosols and small liquid/solid samples having particulates up to several millimeters in diameter in air or other fluids is described. It is constructed from a commercially available, hollow piezoelectric crystal which has been formed with a cylindrical cross-section to tune the resonance frequency of the breathing mode resonance of the crystal to that of the interior cavity of the cylinder. When the resonance frequency of the interior cylindrical cavity is matched to the breathing mode resonance of the cylindrical piezoelectric transducer, the acoustic efficiency for establishing a standing wave pattern in the cavity is high. By deforming the circular cross-section of the transducer, the acoustic force is concentrated along axial regions parallel to the axis of the transducer. The cylinder does not require accurate alignment of a resonant cavity. The concentrated regions of acoustic force cause particles in the fluid to concentrate within the regions of acoustic force for separation from the fluid.

Mathematical modeling of static layer crystallization for propellant grade hydrogen peroxide

NASA Astrophysics Data System (ADS)

Hao, Lin; Chen, Xinghua; Sun, Yaozhou; Liu, Yangyang; Li, Shuai; Zhang, Mengqian

2017-07-01

Hydrogen peroxide (H2O2) is an important raw material widely used in many fields. In this work a mathematical model of heat conduction with a moving boundary was proposed to study the melt crystallization process of hydrogen peroxide which was carried out outside a cylindrical crystallizer. Considering the effects of the temperature of the cooling fluid on the thermal conductivity of crude crystal, the model is an improvement of Guardani's research and can be solved by analytic iteration method. An experiment was designed to measure the thickness of crystal layer with time under different conditions. A series of analysis, including the effects of different refrigerant temperature on crystal growth rate, the effects of different cooling rates on crystal layer growth rate, the effects of crystallization temperature on heat transfer and the model's application scope were conducted based on the comparison between experimental results and simulation results of the model.

EFFECTS OF LASER RADIATION ON MATTER: Calculation of the gain of a C VI laser plasma expanding as a cylinder and a cylindrical layer

NASA Astrophysics Data System (ADS)

Gulov, A. V.; Derzhiev, V. I.; Zhidkov, A. G.; Pritula, A. G.; Chekmezov, A. N.; Yakovlenko, Sergei I.

1990-08-01

Calculations are reported of the gain due to the 3-2 transition in the C VI ion in an expanding plasma cylinder or a cylindrical layer. Under the conditions in the experiments at the Rutherford Appleton Laboratory (Chilton, England) amplification was observed as a result of evaporation of a fairly thin (~ 0.1 μm) cylindrical layer. A peak of the gain was reached in a relatively short time (~ 0.1 ns).

Fluid sampling tool

DOEpatents

Garcia, Anthony R.; Johnston, Roger G.; Martinez, Ronald K.

1999-05-25

A fluid sampling tool for sampling fluid from a container. The tool has a fluid collecting portion which is drilled into the container wall, thereby affixing it to the wall. The tool may have a fluid extracting section which withdraws fluid collected by the fluid collecting section. The fluid collecting section has a fluted shank with an end configured to drill a hole into a container wall. The shank has a threaded portion for tapping the borehole. The shank is threadably engaged to a cylindrical housing having an inner axial passageway sealed at one end by a septum. A flexible member having a cylindrical portion and a bulbous portion is provided. The housing can be slid into an inner axial passageway in the cylindrical portion and sealed to the flexible member. The bulbous portion has an outer lip defining an opening. The housing is clamped into the chuck of a drill, the lip of the bulbous section is pressed against a container wall until the shank touches the wall, and the user operates the drill. Wall shavings (kerf) are confined in a chamber formed in the bulbous section as it folds when the shank advances inside the container. After sufficient advancement of the shank, an o-ring makes a seal with the container wall.

Fluid sampling tool

DOEpatents

Garcia, A.R.; Johnston, R.G.; Martinez, R.K.

1999-05-25

A fluid sampling tool is described for sampling fluid from a container. The tool has a fluid collecting portion which is drilled into the container wall, thereby affixing it to the wall. The tool may have a fluid extracting section which withdraws fluid collected by the fluid collecting section. The fluid collecting section has a fluted shank with an end configured to drill a hole into a container wall. The shank has a threaded portion for tapping the borehole. The shank is threadably engaged to a cylindrical housing having an inner axial passageway sealed at one end by a septum. A flexible member having a cylindrical portion and a bulbous portion is provided. The housing can be slid into an inner axial passageway in the cylindrical portion and sealed to the flexible member. The bulbous portion has an outer lip defining an opening. The housing is clamped into the chuck of a drill, the lip of the bulbous section is pressed against a container wall until the shank touches the wall, and the user operates the drill. Wall shavings (kerf) are confined in a chamber formed in the bulbous section as it folds when the shank advances inside the container. After sufficient advancement of the shank, an o-ring makes a seal with the container wall. 6 figs.

Cylindrical Organic Solar Cells with Carbon Nanotube Charge Collectors

NASA Astrophysics Data System (ADS)

Zakhidov, Dante; Lou, Raymond; Ravi, Nav; Mielczarek, Kamil; Cook, Alexander

2009-10-01

Traditional organic photovoltaic devices (OPV) are built on a flat glass substrates coated by ITO. The maximum area covered by the solar cells is limited to a two dimensional plane. Moreover the light absorption is not maximized for a very thin photoactive layer. We suggest here a cylindrical design which has a vertical structure of optical fiber coated by OPV, with light incident from the side and from edge. The sunlight, entering via a smaller area is captured into optical fiber, which allows more sunlight to be absorbed by a cylindrical OPV overcoating with multiple reflections inside the optical fiber. Instead of using brittle ITO as a hole collecting layer in the cylindrical OPV, transparent sheets of multi-walled carbon nanotubes are applied. Their highly conductive nature and 3-D collection of carriers from the P3HT/PCBM photoactive layer allows for increased efficiency over a planar geometry while keeping the device transparent. Aluminum is used as the electron collecting layer and as a cylindrical mirror. [4pt] [1] Ulbricht, et.al, phys. stat. sol. (b) 243, No. 13, 3528 - 3532 (2006) / DOI 10.1002/pssb.200669181

Miniscrew design and bone response: defining a correlation.

PubMed

Bhalla, Karan; Kalha, Anmol S

2013-01-01

This prospective clinical trial aims at correlating miniscrew implant (MSI) micro/macro architecture, the method of placement, and biologic markers in peri-MSI crevicular fluid (PMICF) as indicators of bone response. A comparative evaluation of surface morphology of the MSIs before placement and after retrieval defines a correlation between the architecture of the MSIs and the bone- implant contact ratio. Two types of MSIs (hybrid and cylindric) were placed in ten patients using a split-mouth technique with the aid of a restricted random number table. Each of the MSIs was placed in the intraradicular area between the second premolar and first molar in the attached gingiva, 4 mm from the cementoenamel junction. The MSIs were immediately loaded, and PMICF was collected on days 0, 7, 14, 21, 28, and 42 and evaluated using a standard laboratory protocol. Surface morphology before placement and after retrieval of the MSI was observed using scanning electron microscopy (SEM) at a magnification of ×11, ×40, and ×1,000. Alkaline phosphatase (ALP) and aspartate aminotransferase (AST) levels observed were lower in the hybrid MSI in comparison to the cylindric MSI. For both MSIs, ALP and AST levels showed a trend of significant increase at days 0, 7, and 14 and then a significant decrease on days 21, 28, and 42. Observations from SEM showed an oxide layer over the entire surface of the bone-expanding hybrid MSI; this layer was observed only at the tip of the cylindric MSI. Levels of both the diagnostic tissue destruction biologic markers ALP and AST are significantly higher in cylindric MSIs compared with hybrid MSIs, indicating a correlation to the type and method of placement of the MSI. The inflammatory markers show a definitive trend, with an elevation until day 14 and a decline after that, indicating an active inflammatory process until day 14 that could be correlated to tissue trauma. Observations from the SEM show a greater oxide layer formation in the hybrid MSI, which could imply a better bone-MSI contact ratio.

Fluid sampling tool

DOEpatents

Johnston, Roger G.; Garcia, Anthony R. E.; Martinez, Ronald K.

2001-09-25

The invention includes a rotatable tool for collecting fluid through the wall of a container. The tool includes a fluid collection section with a cylindrical shank having an end portion for drilling a hole in the container wall when the tool is rotated, and a threaded portion for tapping the hole in the container wall. A passageway in the shank in communication with at least one radial inlet hole in the drilling end and an opening at the end of the shank is adapted to receive fluid from the container. The tool also includes a cylindrical chamber affixed to the end of the shank opposite to the drilling portion thereof for receiving and storing fluid passing through the passageway. The tool also includes a flexible, deformable gasket that provides a fluid-tight chamber to confine kerf generated during the drilling and tapping of the hole. The invention also includes a fluid extractor section for extracting fluid samples from the fluid collecting section.

Novel design and fabrication of a geometrical obstacle-embedded micromixer with notched wall

NASA Astrophysics Data System (ADS)

Wu, Shih-Jeh; Hsu, Hsiang-Chen; Feng, Wen-Jui

2014-09-01

A microfluidic embedded MEMS mixer with a Y-junction type channel and cylindrical obstructions was designed and fabricated for improving the fluid mixing mechanism under low Reynolds number (\\mathit{Re}) condition. The flow field was simulated numerically by software (COMSOL multiphysics®) first. The design was then realized through casting the device in PDMS by lithographed SU-8 photo-resistive mold on silicon wafer. Parametric experimental studies were conducted for optimal design. Two different fluids were pumped into the two legs of the Y-junction channel, and the fluids were broken-up by an embedded cylindrical obstacle in the middle of the tapered micro-channel. The chaotic convection took place in the mixing channel behind the embedded cylindrical obstacles. The flow motion was observed under CCD camera and analyzed by grey level. The developed micromixer in this study can enhance the fluid mixing by the interaction of diffusion and convection for wide range of Reynolds numbers (0.01 < \\mathit{Re} < 100). Experimental results showed that the mixing index reached the required value at 0.1 within 0.024 seconds when the inlet fluid velocity is 0.499 m/s (i.e., at 1200 µl/min flow rate) for merely four cylindrical obstacles. A shorter mixing distance can be accomplished compared to the current devices reported due to faster mixing and shorter mixing time.

Masses of Fluid for Cylindrical Tanks in Rock With Partial Uplift of Bottom Plate

PubMed Central

Taniguchi, Tomoyo; Katayama, Yukihiro

2016-01-01

This study proposes the use of a slice model consisting of a set of thin rectangular tanks for evaluating the masses of fluid contributing to the rocking motion of cylindrical tanks; the effective mass of fluid for rocking motion, that for rocking–bulging interaction, effective moment inertia of fluid for rocking motion and its centroid. They are mathematically or numerically quantified, normalized, tabulated, and depicted as functions of the aspect of tanks for different values of the ratio of the uplift width of the tank bottom plate to the diameter of tank for the designer's convenience. PMID:27303110

High-speed cylindrical collapse of two perfect fluids

NASA Astrophysics Data System (ADS)

Sharif, M.; Ahmad, Zahid

2007-09-01

In this paper, the study of the gravitational collapse of cylindrically distributed two perfect fluid system has been carried out. It is assumed that the collapsing speeds of the two fluids are very large. We explore this condition by using the high-speed approximation scheme. There arise two cases, i.e., bounded and vanishing of the ratios of the pressures with densities of two fluids given by c s , d s . It is shown that the high-speed approximation scheme breaks down by non-zero pressures p 1, p 2 when c s , d s are bounded below by some positive constants. The failure of the high-speed approximation scheme at some particular time of the gravitational collapse suggests the uncertainty on the evolution at and after this time. In the bounded case, the naked singularity formation seems to be impossible for the cylindrical two perfect fluids. For the vanishing case, if a linear equation of state is used, the high-speed collapse does not break down by the effects of the pressures and consequently a naked singularity forms. This work provides the generalisation of the results already given by Nakao and Morisawa (Prog Theor Phys 113:73, 2005) for the perfect fluid.

Nonlinear theory of classical cylindrical Richtmyer-Meshkov instability for arbitrary Atwood numbers

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

Liu, Wan Hai; HEDPS and CAPT, Peking University, Beijing 100871; Ping Yu, Chang, E-mail: champion-yu@163.com

2014-06-15

A nonlinear theory is developed to describe the cylindrical Richtmyer-Meshkov instability (RMI) of an impulsively accelerated interface between incompressible fluids, which is based on both a technique of Padé approximation and an approach of perturbation expansion directly on the perturbed interface rather than the unperturbed interface. When cylindrical effect vanishes (i.e., in the large initial radius of the interface), our explicit results reproduce those [Q. Zhang and S.-I. Sohn, Phys. Fluids 9, 1106 (1996)] related to the planar RMI. The present prediction in agreement with previous simulations [C. Matsuoka and K. Nishihara, Phys. Rev. E 73, 055304(R) (2006)] leads usmore » to better understand the cylindrical RMI at arbitrary Atwood numbers for the whole nonlinear regime. The asymptotic growth rate of the cylindrical interface finger (bubble or spike) tends to its initial value or zero, depending upon mode number of the initial cylindrical interface and Atwood number. The explicit conditions, directly affecting asymptotic behavior of the cylindrical interface finger, are investigated in this paper. This theory allows a straightforward extension to other nonlinear problems related closely to an instable interface.« less

Calculation of AC loss in two-layer superconducting cable with equal currents in the layers

NASA Astrophysics Data System (ADS)

Erdogan, Muzaffer

2016-12-01

A new method for calculating AC loss of two-layer SC power transmission cables using the commercial software Comsol Multiphysics, relying on the approach of the equal partition of current between the layers is proposed. Applying the method to calculate the AC-loss in a cable composed of two coaxial cylindrical SC tubes, the results are in good agreement with the analytical ones of duoblock model. Applying the method to calculate the AC-losses of a cable composed of a cylindrical copper former, surrounded by two coaxial cylindrical layers of superconducting tapes embedded in an insulating medium with tape-on-tape and tape-on-gap configurations are compared. A good agreement between the duoblock model and the numerical results for the tape-on-gap cable is observed.

Frequency dependence of the acoustic radiation force acting on absorbing cylindrical shells.

PubMed

Mitri, Farid G

2005-02-01

The frequency dependence of the radiation force function Y(p) for absorbing cylindrical shells suspended in an inviscid fluid in a plane incident sound field is analysed, in relation to the thickness and the content of their interior hollow region. The theory is modified to include the effect of hysteresis type absorption of compressional and shear waves in the material. The results of numerical calculations are presented for two viscoelastic (lucite and phenolic polymer) materials, with the hollow region filled with water or air indicating how damping and change of the interior fluid inside the shell's hollow region affect the acoustic radiation force. The acoustic radiation force acting on cylindrical lucite shells immersed in a high density fluid (in this case mercury) and filled with water in their hollow region, is also studied.

Squeeze flow between a sphere and a textured wall

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

Chastel, T.; Mongruel, A., E-mail: anne.mongruel@upmc.fr

2016-02-15

The motion of a millimetric sphere, translating in a viscous fluid towards a wettable textured wall, is investigated experimentally. The textures consist of square arrays of cylindrical or square micro-pillars, the height, width, and spacing of which are varied, keeping the periodicity small compared to the sphere radius. An interferometric device is used to measure the sphere vertical displacement, for distances between the sphere and the base of the pillars smaller than 0.1 sphere radius, and with a resolution of 200 nm. At a given distance from the top of the pillars, the sphere velocity is found to be significantlymore » larger than the corresponding velocity for a smooth solid wall. A squeeze flow model of two adjacent fluid layers is developed in the lubrication approximation, one fluid layer having an effective viscosity that reflects the viscous dissipation through the array of pillars. The pressure field in the gap between the sphere and the textured surface is then used to obtain the drag force on the sphere and hence its velocity. Adjustment of the model to the velocity measurements yields the effective viscosity for a given texture. Finally, a correlation between the effective viscosity and the geometry of the pillar array is proposed.« less

Visualization of the energy flow for guided forward and backward waves in and around a fluid-loaded elastic cylindrical shell via the Poynting vector field

NASA Astrophysics Data System (ADS)

Dean, Cleon E.; Braselton, James P.

2004-05-01

Color-coded and vector-arrow grid representations of the Poynting vector field are used to show the energy flow in and around a fluid-loaded elastic cylindrical shell for both forward- and backward-propagating waves. The present work uses a method adapted from a simpler technique due to Kaduchak and Marston [G. Kaduchak and P. L. Marston, ``Traveling-wave decomposition of surface displacements associated with scattering by a cylindrical shell: Numerical evaluation displaying guided forward and backward wave properties,'' J. Acoust. Soc. Am. 98, 3501-3507 (1995)] to isolate unidirectional energy flows.

Diverter/bop system and method for a bottom supported offshore drilling rig

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

Roche, J.R.; Alexander, G.G.; Carbaugh, W.L.

1986-07-01

A system is described adapted for alternative use as a diverter or a blowout preventer for a bottom supported drilling rig and adapted for connection to a permanent housing attached to rig structural members beneath a drilling rig rotary table, the permanent housing having an outlet connectable to a rig fluid system flow line. The system consists of: a fluid flow controller having a controller housing with a lower cylindrical opening and an upper cylindrical opening and a vertical path therebetween and a first outlet passage and a second outlet passage provided in its wall, a packing element disposed withinmore » the controller housing, and annular piston means adapted for moving from a first position to a second position, whereby in the first position the piston means wall prevents interior fluid from communicating with the outlet passages in the controller housing wall and in the second position the piston means wall allows fluid communication of interior fluid with the outlet passages and urges the annular packing element to close about an object extending through the bore of the controller housing or to close the vertical flow path through through the controller housing in the absence of any object in the vertical flow path, means for connecting a vent line to the outlet passage provided in the controller housing wall, a lower telescoping spool having a lower joining means at its lower end for joining alternatively to structural casing or to a mandrel connected to a conductor string cemented within the structural casing and an upper connection means at its upper end for connection to the lower cylindrical opening of the fluid flow controller, and an upper telescoping spool having a lower connection means for connection to the upper cylindrical opening of the fluid flow controller.« less

Sediment morpho-dynamics induced by a swirl-flow: an experimental study

NASA Astrophysics Data System (ADS)

Gonzalez-Vera, Alfredo; Duran-Matute, Matias; van Heijst, Gertjan

2016-11-01

This research focuses on a detailed experimental study of the effect of a swirl-flow over a sediment bed in a cylindrical domain. Experiments were performed in a water-filled cylindrical rotating tank with a bottom layer of translucent polystyrene particles acting as a sediment bed. The experiments started by slowly spinning the tank up until the fluid had reached a solid-body rotation at a selected rotation speed (Ωi). Once this state was reached, a swirl-flow was generated by spinning-down the system to a lower rotation rate (Ωf). Under the flow's influence, particles from the bed were displaced, which changed the bed morphology, and under certain conditions, pattern formation was observed. Changes in the bed height distribution were measured by utilizing a Light Attenuation Technique (LAT). For this purpose, the particle layer was illuminated from below. Images of the transmitted light distribution provided quantitative information about the local thickness of the sediment bed. The experiments revealed a few characteristic regimes corresponding to sediment displacement, pattern formation and the occurrence of particle pick-up. Such regimes depend on both the Reynolds (Re) and Rossby (Ro) numbers. This research is funded by CONACYT (Mexico) through the Ph.D. Grant (383903) and NWO (the Netherlands) through the VENI Grant (863.13.022).

Helical screw viscometer

DOEpatents

Aubert, J.H.; Chapman, R.N.; Kraynik, A.M.

1983-06-30

A helical screw viscometer for the measurement of the viscosity of Newtonian and non-Newtonian fluids comprising an elongated cylindrical container closed by end caps defining a circular cylindrical cavity within the container, a cylindrical rotor member having a helical screw or ribbon flight carried by the outer periphery thereof rotatably carried within the cavity whereby the fluid to be measured is confined in the cavity filling the space between the rotor and the container wall. The rotor member is supported by axle members journaled in the end caps, one axle extending through one end cap and connectable to a drive source. A pair of longitudinally spaced ports are provided through the wall of the container in communication with the cavity and a differential pressure meter is connected between the ports for measuring the pressure drop caused by the rotation of the helical screw rotor acting on the confined fluid for computing viscosity.

Acoustic radiation from the submerged circular cylindrical shell treated with active constrained layer damping

NASA Astrophysics Data System (ADS)

Yuan, Li-Yun; Xiang, Yu; Lu, Jing; Jiang, Hong-Hua

2015-12-01

Based on the transfer matrix method of exploring the circular cylindrical shell treated with active constrained layer damping (i.e., ACLD), combined with the analytical solution of the Helmholtz equation for a point source, a multi-point multipole virtual source simulation method is for the first time proposed for solving the acoustic radiation problem of a submerged ACLD shell. This approach, wherein some virtual point sources are assumed to be evenly distributed on the axial line of the cylindrical shell, and the sound pressure could be written in the form of the sum of the wave functions series with the undetermined coefficients, is demonstrated to be accurate to achieve the radiation acoustic pressure of the pulsating and oscillating spheres respectively. Meanwhile, this approach is proved to be accurate to obtain the radiation acoustic pressure for a stiffened cylindrical shell. Then, the chosen number of the virtual distributed point sources and truncated number of the wave functions series are discussed to achieve the approximate radiation acoustic pressure of an ACLD cylindrical shell. Applying this method, different radiation acoustic pressures of a submerged ACLD cylindrical shell with different boundary conditions, different thickness values of viscoelastic and piezoelectric layer, different feedback gains for the piezoelectric layer and coverage of ACLD are discussed in detail. Results show that a thicker thickness and larger velocity gain for the piezoelectric layer and larger coverage of the ACLD layer can obtain a better damping effect for the whole structure in general. Whereas, laying a thicker viscoelastic layer is not always a better treatment to achieve a better acoustic characteristic. Project supported by the National Natural Science Foundation of China (Grant Nos. 11162001, 11502056, and 51105083), the Natural Science Foundation of Guangxi Zhuang Autonomous Region, China (Grant No. 2012GXNSFAA053207), the Doctor Foundation of Guangxi University of Science and Technology, China (Grant No. 12Z09), and the Development Project of the Key Laboratory of Guangxi Zhuang Autonomous Region, China (Grant No. 1404544).

Three-dimensional smoothed particle hydrodynamics simulation for injection molding flow of short fiber-reinforced polymer composites

NASA Astrophysics Data System (ADS)

He, Liping; Lu, Gang; Chen, Dachuan; Li, Wenjun; Lu, Chunsheng

2017-07-01

This paper investigates the three-dimensional (3D) injection molding flow of short fiber-reinforced polymer composites using a smoothed particle hydrodynamics (SPH) simulation method. The polymer melt was modeled as a power law fluid and the fibers were considered as rigid cylindrical bodies. The filling details and fiber orientation in the injection-molding process were studied. The results indicated that the SPH method could effectively predict the order of filling, fiber accumulation, and heterogeneous distribution of fibers. The SPH simulation also showed that fibers were mainly aligned to the flow direction in the skin layer and inclined to the flow direction in the core layer. Additionally, the fiber-orientation state in the simulation was quantitatively analyzed and found to be consistent with the results calculated by conventional tensor methods.

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

NASA Astrophysics Data System (ADS)

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

2017-12-01

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

Verification of gyrokinetic particle simulation of current-driven instability in fusion plasmas. I. Internal kink mode

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

McClenaghan, J.; Lin, Z.; Holod, I.

The gyrokinetic toroidal code (GTC) capability has been extended for simulating internal kink instability with kinetic effects in toroidal geometry. The global simulation domain covers the magnetic axis, which is necessary for simulating current-driven instabilities. GTC simulation in the fluid limit of the kink modes in cylindrical geometry is verified by benchmarking with a magnetohydrodynamic eigenvalue code. Gyrokinetic simulations of the kink modes in the toroidal geometry find that ion kinetic effects significantly reduce the growth rate even when the banana orbit width is much smaller than the radial width of the perturbed current layer at the mode rational surface.

Sum-Frequency Generation from a Thin Cylindrical Layer

NASA Astrophysics Data System (ADS)

Shamyna, A. A.; Kapshai, V. N.

2018-01-01

In the Rayleigh-Gans-Debye approximation, we have solved the problem of the sum-frequency generation by two plane elliptically polarized electromagnetic waves from the surface of a dielectric particle of a cylindrical shape that is coated by a thin layer possessing nonlinear optical properties. The formulas that describe the sum-frequency field have been presented in the tensor and vector forms for the second-order nonlinear dielectric susceptibility tensor, which was chosen in the general form, containing chiral components. Expressions describing the sum-frequency field from the cylindrical particle ends have been obtained for the case of a nonlinear layer possessing chiral properties. Three-dimensional directivity patterns of the sum-frequency radiation have been analyzed for different combinations of parameters (angles of incidence, degrees of ellipticity, orientations of polarization ellipses, cylindrical particle dimensions). The mathematical properties of the spatial distribution functions of the sum-frequency field, which characterize the symmetry of directivity patterns, have been revealed.

Computer Modeling of the Dynamic Strength of Metal-Plastic Cylindrical Shells Under Explosive Loading

NASA Astrophysics Data System (ADS)

Abrosimov, N. A.; Novosel'tseva, N. A.

2017-05-01

A technique for numerically analyzing the dynamic strength of two-layer metal-plastic cylindrical shells under an axisymmetric internal explosive loading is developed. The kinematic deformation model of the layered package is based on a nonclassical theory of shells. The geometric relations are constructed using relations of the simplest quadratic version of the nonlinear elasticity theory. The stress and strain tensors in the composite macrolayer are related by Hooke's law for an orthotropic body with account of degradation of the stiffness characteristics of the multilayer package due to local failure of some its elementary layers. The physical relations in the metal layer are formulated in terms of a differential theory of plasticity. An energy-correlated resolving system of dynamic equations for the metal-plastic cylindrical shells is derived by minimizing the functional of total energy of the shells as three-dimensional bodies. The numerical method for solving the initial boundary-value problem formulated is based on an explicit variational-difference scheme. The reliability of the technique considered is verified by comparing numerical results with experimental data. An analysis of the ultimate strains and strength of one-layer basalt-and glass-fiber-reinforced plastic and two-layer metalplastic cylindrical shells is carried out.

Numerical Simulation of the Layer-Bylayer Destruction of Cylindrical Shells Under Explosive Loading

NASA Astrophysics Data System (ADS)

Abrosimov, N. A.; Novoseltseva, N. A.

2015-09-01

A technique of numerical analysis of the influence of reinforcement structure on the nature of the dynamic response and the process of layer-by-layer destruction of layered fiberglass cylindrical shells under an axisymmetric internal explosive loading is elaborated. The kinematic model of deformation of the laminate package is based on a nonclassical theory of shells. The geometric dependences are based on simple quadratic relations of the nonlinear theory of elasticity. The relationship between the stress and strain tensors are established by using Hooke's law for orthotropic bodies with account of degradation of stiffness characteristics of the multilayer composite due to the local destruction of some its elementary layers. An energetically consistent system of dynamic equations for composite cylindrical shells is obtained by minimizing the functional of total energy of the shell as a three-dimensional body. The numerical method for solving the formulated initial boundary-value problem is based on an explicit variational-difference scheme. Results confirming the reliability of the method used to analyze the influence of reinforcement structure on the character of destruction and the bearing capacity of pulse-loaded cylindrical shells are presented.

Simultaneous reflectometry and interferometry for measuring thin-film thickness and curvature

NASA Astrophysics Data System (ADS)

Arends, A. A.; Germain, T. M.; Owens, J. F.; Putnam, S. A.

2018-05-01

A coupled reflectometer-interferometer apparatus is described for thin-film thickness and curvature characterization in the three-phase contact line region of evaporating fluids. Validation reflectometry studies are provided for Au, Ge, and Si substrates and thin-film coatings of SiO2 and hydrogel/Ti/SiO2. For interferometry, liquid/air and solid/air interferences are studied, where the solid/air samples consisted of glass/air/glass wedges, cylindrical lenses, and molded polydimethylsiloxane lenses. The liquid/air studies are based on steady-state evaporation experiments of water and isooctane on Si and SiO2/Ti/SiO2 wafers. The liquid thin-films facilitate characterization of both (i) the nano-scale thickness of the absorbed fluid layer and (ii) the macro-scale liquid meniscus thickness, curvature, and curvature gradient profiles. For our validation studies with commercial lenses, the apparatus is shown to measure thickness profiles within 4.1%-10.8% error.

Acoustically excited surface waves on empty or fluid-filled cylindrical and spherical shells

NASA Astrophysics Data System (ADS)

Ahyi, A. Claude; Cao, H.; Raju, P. K.; Werby, M. F.; Bao, X. L.; Überall, H.

2002-05-01

A comparative study is presented of the acoustical excitation of circumferential (surface) waves on fluid-immersed cylindrical or spherical metal shells, which may be either evacuated, or filled with the same or a different fluid. The excited surface waves can manifest themselves by the resonances apparent in the sound scattering amplitude, which they cause upon phase matching following repeated circumnavigations of the target object, or by their re-radiation into the external fluid in the manner of head waves. We plot dispersion curves versus frequency of the surface waves, which for evacuated shells have a generally rising character, while the fluid filling adds an additional set of circumferential waves that descend with frequency. The resonances of these latter waves may also be interpreted as being due to phase matching, but they may alternately be interpreted as constituting the eigenfrequencies of the internal fluid contained in an elastic enclosure.

Measurements of Surfactant Squeeze-out Using Magnetically-Levitated Liquid Bridges

NASA Technical Reports Server (NTRS)

Rosenblatt, Charles

2004-01-01

Liquid bridges: Columns of liquid supported by two solid surfaces. These are generally opposing right circular cylinders in 0g. For a cylindrical bridge of length L and diameter d, in zero g, the maximum slenderness ratio Lambda [L/d] = pi [Rayleigh]. In the presence of gravity the cylindrical shape of an axisymmetric bridge tends to deform. Fluid has a volumetric magnetic susceptibility X. Magnetic levitation has numerous applications in studies of fluids, "soft" and "hard" condensed matter physics, and biophysics

Damping Analysis of Cylindrical Composite Structures with Enhanced Viscoelastic Properties

NASA Astrophysics Data System (ADS)

Kliem, Mathias; Høgsberg, Jan; Vanwalleghem, Joachim; Filippatos, Angelos; Hoschützky, Stefan; Fotsing, Edith-Roland; Berggreen, Christian

2018-04-01

Constrained layer damping treatments are widely used in mechanical structures to damp acoustic noise and mechanical vibrations. A viscoelastic layer is thereby applied to a structure and covered by a stiff constraining layer. When the structure vibrates in a bending mode, the viscoelastic layer is forced to deform in shear mode. Thus, the vibration energy is dissipated as low grade frictional heat. This paper documents the efficiency of passive constrained layer damping treatments for low frequency vibrations of cylindrical composite specimens made of glass fibre-reinforced plastics. Different cross section geometries with shear webs have been investigated in order to study a beneficial effect on the damping characteristics of the cylinder. The viscoelastic damping layers are placed at different locations within the composite cylinder e.g. circumferential and along the neutral plane to evaluate the location-dependent efficiency of constrained layer damping treatments. The results of the study provide a thorough understanding of constrained layer damping treatments and an improved damping design of the cylindrical composite structure. The highest damping is achieved when placing the damping layer in the neutral plane perpendicular to the bending load. The results are based on free decay tests of the composite structure.

Simulations of heart mechanics over the cardiac cycle

NASA Astrophysics Data System (ADS)

Tavoularis, Stavros; Doyle, Matthew; Bourgault, Yves

2009-11-01

This study is concerned with the numerical simulation of blood flow and myocardium motion with fluid-structure interaction of the left ventricle (LV) of a canine heart over the entire cardiac cycle. The LV geometry is modeled as a series of nested prolate ellipsoids and is capped with cylindrical tubes representing the inflow and outflow tracts. The myocardium is modeled as a multi-layered, slightly compressible, transversely isotropic, hyperelastic material, with each layer having different principal directions to approximate the fibrous structure. Blood is modeled as a slightly compressible Newtonian fluid. Blood flow into and out of the LV is driven by left atrial and aortic pressures applied at the distal ends of the inflow and outflow tracts, respectively, along with changes in the stresses in the myocardium caused by time-dependent changes in its material properties, which simulate the cyclic contraction and relaxation of the muscle fibers. Numerical solutions are obtained with the use of a finite element code. The computed temporal and spatial variations of pressure and velocity in the blood and stresses and strains in the myocardium will be discussed and compared to physiological data. The variation of the LV cavity volume over the cardiac cycle will also be discussed.

Experimental investigation of supersonic low pressure air plasma flows obtained with different arc-jet operating conditions

NASA Astrophysics Data System (ADS)

Lago, Viviana; Ndiaye, Abdoul-Aziz

2012-11-01

A stationary arc-jet plasma flow at low pressure is used to simulate some properties of the gas flow surrounding a vehicle during its entry into celestial body's atmospheres. This paper presents an experimental study concerning plasmas simulating a re-entry into our planet. Optical measurements have been carried out for several operating plasma conditions in the free stream, and in the shock layer formed in front of a flat cylindrical plate, placed in the plasma jet. The analysis of the spectral radiation enabled the identification of the emitting species, the determination of the rotational and vibrational temperatures in the free-stream and in the shock layer and the determination of the distance of the shock to the flat plate face. Some plasma fluid parameters like, stagnation pressure, specific enthalpy and heat flux have been determined experimentally along the plasma-jet axis.

Exact solution of conductive heat transfer in cylindrical composite laminate

NASA Astrophysics Data System (ADS)

Kayhani, M. H.; Shariati, M.; Nourozi, M.; Karimi Demneh, M.

2009-11-01

This paper presents an exact solution for steady-state conduction heat transfer in cylindrical composite laminates. This laminate is cylindrical shape and in each lamina, fibers have been wound around the cylinder. In this article heat transfer in composite laminates is being investigated, by using separation of variables method and an analytical relation for temperature distribution in these laminates has been obtained under specific boundary conditions. Also Fourier coefficients in each layer obtain by solving set of equations that related to thermal boundary layer conditions at inside and outside of the cylinder also thermal continuity and heat flux continuity between each layer is considered. In this research LU factorization method has been used to solve the set of equations.

Dynamic Deformation and Collapse of Granular Columns

NASA Astrophysics Data System (ADS)

Uenishi, K.; Tsuji, K.; Doi, S.

2009-12-01

Large dynamic deformation of granular materials may be found in nature not only in the failure of slopes and cliffs — due to earthquakes, rock avalanches, debris flows and landslides — but also in earthquake faulting itself. Granular surface flows often consist of solid grains and intergranular fluid, but the effect of the fluid may be usually negligible because the volumetric concentration of grains is in many cases high enough for interparticle forces to dominate momentum transport. Therefore, the investigation of dry granular flow of a mass might assist in further understanding of the above mentioned geophysical events. Here, utilizing a high-speed digital video camera system, we perform a simple yet fully-controlled series of laboratory experiments related to the collapse of granular columns. We record, at an interval of some microseconds, the dynamic transient granular mass flow initiated by abrupt release of a tube that contains dry granular materials. The acrylic tube is partially filled with glass beads and has a cross-section of either a fully- or semi-cylindrical shape. Upon sudden removal of the tube, the granular solid may fragment under the action of its own weight and the particles spread on a rigid horizontal plane. This study is essentially the extension of the previous ones by Lajeunesse et al. (Phys. Fluids 2004) and Uenishi and Tsuji (JPGU 2008), but the striped layers of particles in a semi-cylindrical tube, newly introduced in this contribution, allow us to observe the precise particle movement inside the granular column: The development of slip lines inside the column and the movement of particles against each other can be clearly identified. The major controlling parameters of the spreading dynamics are the initial aspect ratio of the granular (semi-)cylindrical column, the frictional properties of the horizontal plane (substrate) and the size of beads. We show the influence of each parameter on the average flow velocity and final radius and height of the deposit, i.e., the fraction of granular mass mobilized by the flow, and the final shape of the deposit.

A description on plasma background effect in growth rate of THz waves in a metallic cylindrical waveguide, including a dielectric tube and two current sources

NASA Astrophysics Data System (ADS)

Hajijamali-Arani, Z.; Jazi, B.

2018-04-01

The propagation of slow waves in a dielectric tube surrounded by a long cylindrical metallic waveguide is investigated. The dielectric tube located in a background region of plasma under two different states A and B. In the A-state the dielectric tube hollow filled with the plasma and in the B-state the outer surface of dielectric tube has been covered by the plasma layer. There are two relativistic electron beams with opposite velocities injected in the waveguide as the energy sources. Using the fluid theory for the plasmas, the Cherenkov instability in the mentioned waveguide will be analyzed. The dispersion relations of E-mode waves for the states A, B have been obtained. The time growth rate of surface waves are compared with each other for two cases A and B. The effect of plasma region on time growth rate of the waves, will be investigated. In all cases it will be shown, while an electron beam is responsible for instability, another electron beam plays a stabilizing role.

Ultracentrifuge for separating fluid mixtures

DOEpatents

Lowry, Ralph A.

1976-01-01

1. A centrifuge for the separation of fluid mixtures having light and heavy fractions comprising a cylindrical rotor, disc type end-plugs closing the ends of the rotor, means for mounting said rotor for rotation about its cylindrical axis, a housing member enclosing the rotor, a vacuum chamber in said housing about the central portion of the rotor, a collection chamber at each end of the housing, the innermost side of which is substantially formed by the outer face of the end-plug, means for preventing flow of the fluid from the collection chambers to said vacuum chamber, at least one of said end-plugs having a plurality of holes therethrough communicating between the collection chamber adjacent thereto and the inside of the rotor to induce countercurrent flow of the fluid in the centrifuge, means for feeding fluid to be processed into the centrifuge, means communicating with the collection chambers to extract the light and heavy separated fractions of the fluid, and means for rotating the rotor.

Interfacial Phenomena of Magnetic Fluid with Permanent Magnet in a Longitudinally Excited Container

NASA Astrophysics Data System (ADS)

Sudo, Seiichi; Wakuda, Hirofumi; Yano, Tetsuya

2008-02-01

This paper describes the magnetic fluid sloshing in a longitudinally excited container. Liquid responses of magnetic fluid with a permanent magnet in a circular cylindrical container subject to vertical vibration are investigated. Experiments are performed on a vibration- testing system which provided longitudinal excitation. A cylindrical container made with the acrylic plastic is used in the experiment. A permanent magnet is in the state of floating in a magnetic fluid. The disk-shaped and ring-shaped magnets are examined. The different interfacial phenomena from the usual longitudinal liquid sloshing are observed. It is found that the wave motion frequency of magnetic fluid with a disk-shaped magnet in the container subject to vertical vibration is exactly same that of the excitation. In the case of ring-shaped magnet, the first symmetrical mode of one-half subharmonic response is dominant at lower excitation frequencies. The magnetic fluid disintegration of the free surface was also observed by a high-speed video camera system.

Novel Shapes of Miscible Interfaces Observed

NASA Technical Reports Server (NTRS)

Balasubramaniam, Ramaswamy; Rashidnia, Nasser

2001-01-01

The dynamics of miscible displacements in a cylindrical tube are being investigated experimentally and numerically, with a view to understand the complex processes that occur, for example, in enhanced oil recovery, hydrology, and filtration. We have observed complex shapes of the interface between two liquids that mix with each other when the less viscous liquid is displaced by the more viscous one in a tube. A less viscous fluid that displaces a more viscous fluid is known to propagate in the form of a "finger," and a flight experiment proposed by Maxworthy et al. to investigate the miscible-interface dynamics is currently being developed by NASA. From the current theory of miscible displacements, which was developed for a porous medium satisfying Darcy's law, it can be shown that in the absence of gravity the interface between the fluids is destabilized and thus susceptible to fingering only when a more viscous fluid is displaced by a less viscous one. Therefore, if the interface is initially flat and the more viscous fluid displaces the less viscous fluid, the interface ought to be stable and remain flat. However, numerical simulations by Chen and Meiburg for such displacement in a cylindrical tube show that the interface is unstable and a finger of the more viscous fluid is indeed formed. Preliminary experiments performed at the NASA Glenn Research Center show that not only can fingering occur when the more viscous fluid displaces a less viscous one in a cylindrical tube, but also that under certain conditions the advancing finger achieves a sinuous or snakelike shape. These experiments were performed using silicone oils in a vertical pipette of small diameter. In the initial configuration, the more viscous fluid rested on top of the less viscous one, and the interface was nominally flat. A dye was added to the upper liquid for ease of observation of the interface between the fluids. The flow was initiated by draining the lower fluid from the bottom of the pipette, at speeds less than 0.1 mm/sec.

STABILITY OF A CYLINDRICAL SOLUTE-SOLVENT INTERFACE: EFFECT OF GEOMETRY, ELECTROSTATICS, AND HYDRODYNAMICS.

PubMed

Li, B O; Sun, Hui; Zhou, Shenggao

The solute-solvent interface that separates biological molecules from their surrounding aqueous solvent characterizes the conformation and dynamics of such molecules. In this work, we construct a solvent fluid dielectric boundary model for the solvation of charged molecules and apply it to study the stability of a model cylindrical solute-solvent interface. The motion of the solute-solvent interface is defined to be the same as that of solvent fluid at the interface. The solvent fluid is assumed to be incompressible and is described by the Stokes equation. The solute is modeled simply by the ideal-gas law. All the viscous force, hydrostatic pressure, solute-solvent van der Waals interaction, surface tension, and electrostatic force are balanced at the solute-solvent interface. We model the electrostatics by Poisson's equation in which the solute-solvent interface is treated as a dielectric boundary that separates the low-dielectric solute from the high-dielectric solvent. For a cylindrical geometry, we find multiple cylindrically shaped equilibrium interfaces that describe polymodal (e.g., dry and wet) states of hydration of an underlying molecular system. These steady-state solutions exhibit bifurcation behavior with respect to the charge density. For their linearized systems, we use the projection method to solve the fluid equation and find the dispersion relation. Our asymptotic analysis shows that, for large wavenumbers, the decay rate is proportional to wavenumber with the proportionality half of the ratio of surface tension to solvent viscosity, indicating that the solvent viscosity does affect the stability of a solute-solvent interface. Consequences of our analysis in the context of biomolecular interactions are discussed.

Cold isopressing method

DOEpatents

Chen, Jack C.; Stawisuck, Valerie M.; Prasad, Ravi

2003-01-01

A cold isopressing method in which two or more layers of material are formed within an isopressing mold. One of the layers consists of a tape-cast film. The layers are isopressed within the isopressing mold, thereby to laminate the layers and to compact the tape-cast film. The isopressing mold can be of cylindrical configuration with the layers being coaxial cylindrical layers. The materials used in forming the layers can contain green ceramic materials and the resultant structure can be fired and sintered as necessary and in accordance with known methods to produce a finished composite, ceramic structure. Further, such green ceramic materials can be of the type that are capable of conducting hydrogen or oxygen ions at high temperature with the object of utilizing the finished composite ceramic structure as a ceramic membrane element.

Macromolecular shape and interactions in layer-by-layer assemblies within cylindrical nanopores.

PubMed

Lazzara, Thomas D; Lau, K H Aaron; Knoll, Wolfgang; Janshoff, Andreas; Steinem, Claudia

2012-01-01

Layer-by-layer (LbL) deposition of polyelectrolytes and proteins within the cylindrical nanopores of anodic aluminum oxide (AAO) membranes was studied by optical waveguide spectroscopy (OWS). AAO has aligned cylindrical, nonintersecting pores with a defined pore diameter d(0) and functions as a planar optical waveguide so as to monitor, in situ, the LbL process by OWS. The LbL deposition of globular proteins, i.e., avidin and biotinylated bovine serum albumin was compared with that of linear polyelectrolytes (linear-PEs), both species being of similar molecular weight. LbL deposition within the cylindrical AAO geometry for different pore diameters (d(0) = 25-80 nm) for the various macromolecular species, showed that the multilayer film growth was inhibited at different maximum numbers of LbL steps (n(max)). The value of n(max) was greatest for linear-PEs, while proteins had a lower value. The cylindrical pore geometry imposes a physical limit to LbL growth such that n(max) is strongly dependent on the overall internal structure of the LbL film. For all macromolecular species, deposition was inhibited in native AAO, having pores of d(0) = 25-30 nm. Both, OWS and scanning electron microscopy showed that LbL growth in larger AAO pores (d(0) > 25-30 nm) became inhibited when approaching a pore diameter of d(eff,n_max) = 25-35 nm, a similar size to that of native AAO pores, with d(0) = 25-30 nm. For a reasonable estimation of d(eff,n_max), the actual volume occupied by a macromolecular assembly must be taken into consideration. The results clearly show that electrostatic LbL allowed for compact macromolecular layers, whereas proteins formed loosely packed multilayers.

Laminar boundary layer near the rotating end wall of a confined vortex

NASA Astrophysics Data System (ADS)

Shakespeare, W. J.; Levy, E. K.

1982-06-01

The results of an experimental and theoretical investigation of the fluid mechanics in a confined vortex are discussed with particular emphasis on behavior away from the axis of symmetry and near the end walls. The vortex is generated in a rotating cylindrical chamber with an exit opening in one end. Both end walls rotate. For the range of flow rates and swirl ratios (S between 1 and 5) of interest here, the flow field far from the end walls behaves as inviscid and irrotational; and the end wall boundary layers are thin and laminar. Measurements and calculations of tangential and radial velocity in the end wall region show the development of a secondary flow resulting in a strong velocity 'overshoot' in the radial component. Results illustrating the nature of the velocity variations on the end walls are presented; and it is shown that the mass flow rate through the end wall boundary layers, while only a small fraction of the total flow, increases with increasing swirl and with decreasing total flow rate through the chamber.

Ductile shear zones beneath strike-slip faults: Implications for the thermomechanics of the San Andreas fault zone

USGS Publications Warehouse

Thatcher, W.; England, P.C.

1998-01-01

We have carried out two-dimensional (2-D) numerical experiments on the bulk flow of a layer of fluid that is driven in a strike-slip sense by constant velocities applied at its boundaries. The fluid has the (linearized) conventional rheology assumed to apply to lower crust/upper mantle rocks. The temperature dependence of the effective viscosity of the fluid and the shear heating that accompanies deformation have been incorporated into the calculations, as has thermal conduction in an overlying crustal layer. Two end-member boundary conditions have been considered, corresponding to a strong upper crust driving a weaker ductile substrate and a strong ductile layer driving a passive, weak crust. In many cases of practical interest, shear heating is concentrated close to the axial plane of the shear zone for either boundary condition. For these cases, the resulting steady state temperature field is well approximated by a cylindrical heat source embedded in a conductive half-space at a depth corresponding to the top of the fluid layer. This approximation, along with the application of a theoretical result for one-dimensional shear zones, permits us to obtain simple analytical approximations to the thermal effects of 2-D ductile shear zones for a range of assumed rheologies and crustal geotherms, making complex numerical calculations unnecessary. Results are compared with observable effects on heat flux near the San Andreas fault using constraints on the slip distribution across the entire fault system. Ductile shearing in the lower crust or upper mantle can explain the observed increase in surface heat flux southeast of the Mendocino triple junction and match the amplitude of the regional heat flux anomaly in the California Coast Ranges. Because ductile dissipation depends only weakly on slip rate, faults moving only a few millimeters per year can be important heat sources, and the superposition of effects of localized ductile shearing on both currently active and now inactive strands of the San Andreas system can explain the breadth of the heat flux anomaly across central California.

Analytical and numerical solutions for mass diffusion in a composite cylindrical body

NASA Astrophysics Data System (ADS)

Kumar, A.

1980-12-01

The analytical and numerical solution techniques were investigated to study moisture diffusion problems in cylindrical bodies that are assumed to be composed of a finite number of layers of different materials. A generalized diffusion model for an n-layer cylindrical body with discontinuous moisture content at the interfaces was developed and the formal solutions were obtained. The model is to be used for describing mass transfer rates of any composite body, such as an ear of corn which could be assumed of consisting two different layers: the inner core represents the woody cob and the outer cylinder represents the kernel layer. Data describing the fully exposed drying characteristics of ear corn at high air velocity were obtained under different drying conditions. Ear corns were modeled as homogeneous bodies since composite model did not improve the fit substantially. A computer program using multidimensional optimization technique showed that diffusivity was an exponential function of moisture content and an arrhenius function of temperature of drying air.

Improved 3-omega measurement of thermal conductivity in liquid, gases, and powders using a metal-coated optical fiber.

PubMed

Schiffres, Scott N; Malen, Jonathan A

2011-06-01

A novel 3ω thermal conductivity measurement technique called metal-coated 3ω is introduced for use with liquids, gases, powders, and aerogels. This technique employs a micron-scale metal-coated glass fiber as a heater/thermometer that is suspended within the sample. Metal-coated 3ω exceeds alternate 3ω based fluid sensing techniques in a number of key metrics enabling rapid measurements of small samples of materials with very low thermal effusivity (gases), using smaller temperature oscillations with lower parasitic conduction losses. Its advantages relative to existing fluid measurement techniques, including transient hot-wire, steady-state methods, and solid-wire 3ω are discussed. A generalized n-layer concentric cylindrical periodic heating solution that accounts for thermal boundary resistance is presented. Improved sensitivity to boundary conductance is recognized through this model. Metal-coated 3ω was successfully validated through a benchmark study of gases and liquids spanning two-orders of magnitude in thermal conductivity. © 2011 American Institute of Physics

Non-Newtonian fluid structure interaction in flexible biomimetic microchannels

NASA Astrophysics Data System (ADS)

Kiran, M.; Dasgupta, Sunando; Chakraborty, Suman

2017-11-01

To investigate the complex fluid structure interactions in a physiologically relevant microchannel with deformable wall and non-Newtonian fluid that flows within it, we fabricated cylindrical microchannels of various softness out of PDMS. Experiments to measure the transient pressure drop across the channel were carried out with high sampling frequencies to capture the intricate flow physics. In particular, we showed that the waveforms varies greatly for each of the non-Newtonian and Newtonian cases for both non-deformable and deformable microchannels in terms of the peak amplitude, r.m.s amplitude and the crest factor. In addition, we carried out frequency sweep experiments to evaluate the frequency response of the system. We believe that these results will aid in the design of polymer based microfluidic phantoms for arterial FSI studies, and in particular for studying blood analog fluids in cylindrical microchannels as well as developing frequency specific Lab-on-chip systems for medical diagnostics.

A numerical comparison with an exact solution for the transient response of a cylinder immersed in a fluid. [computer simulated underwater tests to determine transient response of a submerged cylindrical shell

NASA Technical Reports Server (NTRS)

Giltrud, M. E.; Lucas, D. S.

1979-01-01

The transient response of an elastic cylindrical shell immersed in an acoustic media that is engulfed by a plane wave is determined numerically. The method applies to the USA-STAGS code which utilizes the finite element method for the structural analysis and the doubly asymptotic approximation for the fluid-structure interaction. The calculations are compared to an exact analysis for two separate loading cases: a plane step wave and an exponentially decaying plane wave.

High amplitude nonlinear acoustic wave driven flow fields in cylindrical and conical resonators.

PubMed

Antao, Dion Savio; Farouk, Bakhtier

2013-08-01

A high fidelity computational fluid dynamic model is used to simulate the flow, pressure, and density fields generated in a cylindrical and a conical resonator by a vibrating end wall/piston producing high-amplitude standing waves. The waves in the conical resonator are found to be shock-less and can generate peak acoustic overpressures that exceed the initial undisturbed pressure by two to three times. A cylindrical (consonant) acoustic resonator has limitations to the output response observed at one end when the opposite end is acoustically excited. In the conical geometry (dissonant acoustic resonator) the linear acoustic input is converted to high energy un-shocked nonlinear acoustic output. The model is validated using past numerical results of standing waves in cylindrical resonators. The nonlinear nature of the harmonic response in the conical resonator system is further investigated for two different working fluids (carbon dioxide and argon) operating at various values of piston amplitude. The high amplitude nonlinear oscillations observed in the conical resonator can potentially enhance the performance of pulse tube thermoacoustic refrigerators and these conical resonators can be used as efficient mixers.

Orbitally shaken shallow fluid layers. I. Regime classification

NASA Astrophysics Data System (ADS)

Alpresa, Paola; Sherwin, Spencer; Weinberg, Peter; van Reeuwijk, Maarten

2018-03-01

Orbital shakers are simple devices that provide mixing, aeration, and shear stress at multiple scales and high throughput. For this reason, they are extensively used in a wide range of applications from protein production to bacterial biofilms and endothelial cell experiments. This study focuses on the behaviour of orbitally shaken shallow fluid layers in cylindrical containers. In order to investigate the behaviour over a wide range of different conditions, a significant number of numerical simulations are carried out under different configuration parameters. We demonstrate that potential theory—despite the relatively low Reynolds number of the system—describes the free-surface amplitude well and the velocity field reasonably well, except when the forcing frequency is close to a natural frequency and resonance occurs. By classifying the simulations into non-breaking, breaking, and breaking with part of the bottom uncovered, it is shown that the onset of wave breaking is well described by Δh/(2R) = 0.7Γ, where Δh is the free-surface amplitude, R is the container radius, and Γ is the container aspect ratio; Δh can be well approximated using the potential theory. This result is in agreement with standard wave breaking theories although the significant inertial forcing causes wave breaking at lower amplitudes.

Fluid-structure interactions in compressible cavity flows

DOE PAGES

Wagner, Justin L.; Casper, Katya Marie; Beresh, Steven J.; ...

2015-06-08

Experiments were performed to understand the complex fluid-structure interactions that occur during aircraft internal store carriage. A cylindrical store was installed in a rectangular cavity having a length-to-depth ratio of 3.33 and a length-to-width ratio of 1. The Mach number ranged from 0.6 to 2.5 and the incoming boundary layer was turbulent. Fast-response pressure measurements provided aeroacoustic loading in the cavity, while triaxial accelerometers provided simultaneous store response. Despite occupying only 6% of the cavity volume, the store significantly altered the cavity acoustics. The store responded to the cavity flow at its natural structural frequencies, and it exhibited a directionallymore » dependent response to cavity resonance. Specifically, cavity tones excited the store in the streamwise and wall-normal directions consistently, whereas a spanwise response was observed only occasionally. Also, the streamwise and wall-normal responses were attributed to the longitudinal pressure waves and shear layer vortices known to occur during cavity resonance. Although the spanwise response to cavity tones was limited, broadband pressure fluctuations resulted in significant spanwise accelerations at store natural frequencies. As a result, the largest vibrations occurred when a cavity tone matched a structural natural frequency, although energy was transferred more efficiently to natural frequencies having predominantly streamwise and wall-normal motions.« less

Velocity Inversion In Cylindrical Couette Gas Flows

NASA Astrophysics Data System (ADS)

Dongari, Nishanth; Barber, Robert W.; Emerson, David R.; Zhang, Yonghao; Reese, Jason M.

2012-05-01

We investigate a power-law probability distribution function to describe the mean free path of rarefied gas molecules in non-planar geometries. A new curvature-dependent model is derived by taking into account the boundary-limiting effects on the molecular mean free path for surfaces with both convex and concave curvatures. In comparison to a planar wall, we find that the mean free path for a convex surface is higher at the wall and exhibits a sharper gradient within the Knudsen layer. In contrast, a concave wall exhibits a lower mean free path near the surface and the gradients in the Knudsen layer are shallower. The Navier-Stokes constitutive relations and velocity-slip boundary conditions are modified based on a power-law scaling to describe the mean free path, in accordance with the kinetic theory of gases, i.e. transport properties can be described in terms of the mean free path. Velocity profiles for isothermal cylindrical Couette flow are obtained using the power-law model. We demonstrate that our model is more accurate than the classical slip solution, especially in the transition regime, and we are able to capture important non-linear trends associated with the non-equilibrium physics of the Knudsen layer. In addition, we establish a new criterion for the critical accommodation coefficient that leads to the non-intuitive phenomena of velocity-inversion. Our results are compared with conventional hydrodynamic models and direct simulation Monte Carlo data. The power-law model predicts that the critical accommodation coefficient is significantly lower than that calculated using the classical slip solution and is in good agreement with available DSMC data. Our proposed constitutive scaling for non-planar surfaces is based on simple physical arguments and can be readily implemented in conventional fluid dynamics codes for arbitrary geometric configurations.

Apparatus and method for aerodynamic levitation

NASA Technical Reports Server (NTRS)

Williamson, John W. (Inventor); al-Darwish, Mohamad M. (Inventor); Cashen, Grant E. (Inventor)

1993-01-01

An apparatus for the levitation of a liquid drop by a fluid flow comprising a profile generator, a fluid flow supply means operatively connected to the profile generator. The profile generator includes an elongate cylindrical shell in which is contained a profiling means for configuring the velocity profile of the fluid flow exiting the profile generator.

Preparation and magnetic properties of cylindrical NiFe films and antidot arrays.

PubMed

Sanz, R; Navas, D; Vazquez, M; Hernández-Vélez, M; Ross, C A

2010-10-01

Continuous NiFe (Permalloy) cylindrical films and arrays of cylindrical NiFe antidots 7 nm thick have been prepared by sputtering onto cylindrical aluminum wires and onto wires anodized to form a porous anodic alumina layer. The antidots are arranged in a close-packed pattern determined by the hexagonal pore arrangement in the porous alumina, with period 103 nm and diameter 42 nm. Hysteresis loops were measured at different angles with respect to the cylinder axis and indicate an easy plane normal to the radius of the wire. The antidots enhance the coercivity compared to the continuous cylindrical film.

Self-charging metering and dispensing device for fluids

NASA Technical Reports Server (NTRS)

Hooper, S. L.; Setzer, D. (Inventor)

1984-01-01

A self-metering and dispensing device for fluids obtained from a pressurized fluid supply is discussed. Tubing and valving means permit the introduction of fluid into and discharge from a closed cylindrical reservoir. The reservoir contains a slideably disposed piston co-acting with a coil compression spring, with piston travel determining the amount of fluid in the reservoir. Once the determined amount of fluid is introduced into the reservoir, the fluid is discharged by the force of the coil compression spring acting upon the piston.

Numeric and fluid dynamic representation of tornadic double vortex thunderstorms

NASA Technical Reports Server (NTRS)

Connell, J. R.; Marquart, E. J.; Frost, W.; Boaz, W.

1980-01-01

Current understanding of a double vortex thunderstorm involves a pair of contra-rotating vortices that exists in the dynamic updraft. The pair is believed to be a result of a blocking effect which occurs when a cylindrical thermal updraft of a thunderstorm protrudes into the upper level air and there is a large amount of vertical wind shear between the low level and upper level air layers. A numerical tornado prediction scheme based on the double vortex thunderstorm was developed. The Energy-Shear Index (ESI) is part of the scheme and is calculated from radiosonde measurements. The ESI incorporates parameters representative of thermal instability and blocking effect, and indicates appropriate environments for which the development of double vortex thunderstorms is likely.

A Numerical Study of Coupled Non-Linear Equations of Thermo-Viscous Fluid Flow in Cylindrical Geometry

NASA Astrophysics Data System (ADS)

Pothanna, N.; Aparna, P.; Gorla, R. S. R.

2017-12-01

In this paper we present numerical solutions to coupled non-linear governing equations of thermo-viscous fluid flow in cylindrical geometry using MATHEMATICA software solver. The numerical results are presented in terms of velocity, temperature and pressure distribution for various values of the material parameters such as the thermo-mechanical stress coefficient, thermal conductivity coefficient, Reiner Rivlin cross viscosity coefficient and the Prandtl number in the form of tables and graphs. Also, the solutions to governing equations for slow steady motion of a fluid have been obtained numerically and compared with the existing analytical results and are found to be in excellent agreement. The results of the present study will hopefully enable a better understanding applications of the flow under consideration.

A semi-analytical solution for elastic analysis of rotating thick cylindrical shells with variable thickness using disk form multilayers.

PubMed

Zamani Nejad, Mohammad; Jabbari, Mehdi; Ghannad, Mehdi

2014-01-01

Using disk form multilayers, a semi-analytical solution has been derived for determination of displacements and stresses in a rotating cylindrical shell with variable thickness under uniform pressure. The thick cylinder is divided into disk form layers form with their thickness corresponding to the thickness of the cylinder. Due to the existence of shear stress in the thick cylindrical shell with variable thickness, the equations governing disk layers are obtained based on first-order shear deformation theory (FSDT). These equations are in the form of a set of general differential equations. Given that the cylinder is divided into n disks, n sets of differential equations are obtained. The solution of this set of equations, applying the boundary conditions and continuity conditions between the layers, yields displacements and stresses. A numerical solution using finite element method (FEM) is also presented and good agreement was found.

A Semi-Analytical Solution for Elastic Analysis of Rotating Thick Cylindrical Shells with Variable Thickness Using Disk Form Multilayers

PubMed Central

Zamani Nejad, Mohammad; Jabbari, Mehdi; Ghannad, Mehdi

2014-01-01

Using disk form multilayers, a semi-analytical solution has been derived for determination of displacements and stresses in a rotating cylindrical shell with variable thickness under uniform pressure. The thick cylinder is divided into disk form layers form with their thickness corresponding to the thickness of the cylinder. Due to the existence of shear stress in the thick cylindrical shell with variable thickness, the equations governing disk layers are obtained based on first-order shear deformation theory (FSDT). These equations are in the form of a set of general differential equations. Given that the cylinder is divided into n disks, n sets of differential equations are obtained. The solution of this set of equations, applying the boundary conditions and continuity conditions between the layers, yields displacements and stresses. A numerical solution using finite element method (FEM) is also presented and good agreement was found. PMID:24719582

Acoustic Radiation from High-Speed Turbulent Boundary Layers in a Tunnel-Like Environment

NASA Technical Reports Server (NTRS)

Duan, Lian; Choudhari, Meelan M.; Zhang, Chao

2015-01-01

Direct numerical simulation of acoustic radiation from a turbulent boundary layer in a cylindrical domain will be conducted under the flow conditions corresponding to those at the nozzle exit of the Boeing/AFOSR Mach-6 Quiet Tunnel (BAM6QT) operated under noisy-flow conditions with a total pressure p(sub t) of 225 kPa and a total temperature of T(sub t) equal to 430 K. Simulations of acoustic radiation from a turbulent boundary layer over a flat surface are used as a reference configuration to illustrate the effects of the cylindrical enclosure. A detailed analysis of acoustic freestream disturbances in the cylindrical domain will be reported in the final paper along with a discussion pertaining to the significance of the flat-plate acoustic simulations and guidelines concerning the modeling of the effects of an axisymmetric tunnel wall on the noise field.

Role of dielectric constant in electrohydrodynamics of conducting fluids

NASA Technical Reports Server (NTRS)

Rhodes, Percy H.; Snyder, Robert S.; Roberts, Glyn O.

1992-01-01

Electrohydrodynamic (EHD) flows are driven by the interaction of an electric field with variations in electric conductivity or dielectric constant. In reported EHD experiments on the deformation of drops of immiscible dielectric fluids, the role of conductivity has tended to overshadow the role of dielectric constant. Often, large conductivity contrasts were convenient because the conductivities of the dielectric fluid were relatively uncertain. As a result, the observed effects were always qualitatively the same as if there had been no contrast in dielectric constant. Our early experiments studying the EHC deformations of cylindrical streams readily showed the conductivity effect but the dielectric constant effect was not discernible. We have modified our flow chamber and improved our method of observation and can now see an unequivocal dielectric constant effect which is in agreement with the prior theory. In this paper we first give a brief description of the physics of charge buildup at the interface of an immersed spherical drop or flowing cylindrical sample stream and then show how these charge distributions lead to interface distortions and accompanying viscous flows which constitute EHD. We next review theory and experiment describing the deformation of spherical drops. We show that in the reported drop deformation experiments, the contrast in dielectric constant was never sufficient to reverse the deformation due to the conductivity contrast. We review our work describing the deformation of a cylindrical stream of one fluid flowing in a parallel flow of another, and we compare the deformation equations with those for spherical drops. Finally, we show a definite experimental dielectric constant effect for cylindrical stream of aqueous polystyrene latex suspension. The dielectric constant varies with the frequency of the imposed electric field, and the associated EHD flow change is very apparent.

Anode optimization for miniature electronic brachytherapy X-ray sources using Monte Carlo and computational fluid dynamic codes

PubMed Central

Khajeh, Masoud; Safigholi, Habib

2015-01-01

A miniature X-ray source has been optimized for electronic brachytherapy. The cooling fluid for this device is water. Unlike the radionuclide brachytherapy sources, this source is able to operate at variable voltages and currents to match the dose with the tumor depth. First, Monte Carlo (MC) optimization was performed on the tungsten target-buffer thickness layers versus energy such that the minimum X-ray attenuation occurred. Second optimization was done on the selection of the anode shape based on the Monte Carlo in water TG-43U1 anisotropy function. This optimization was carried out to get the dose anisotropy functions closer to unity at any angle from 0° to 170°. Three anode shapes including cylindrical, spherical, and conical were considered. Moreover, by Computational Fluid Dynamic (CFD) code the optimal target-buffer shape and different nozzle shapes for electronic brachytherapy were evaluated. The characterization criteria of the CFD were the minimum temperature on the anode shape, cooling water, and pressure loss from inlet to outlet. The optimal anode was conical in shape with a conical nozzle. Finally, the TG-43U1 parameters of the optimal source were compared with the literature. PMID:26966563

On effects of topography in rotating flows

NASA Astrophysics Data System (ADS)

Burmann, Fabian; Noir, Jerome; Jackson, Andrew

2017-11-01

Both, seismological studies and geodynamic arguments suggest that there is significant topography at the core mantle boundary (CMB). This leads to the question whether the topography of the CMB could influence the flow in the Earth's outer core. As a preliminary experiment, we investigate the effects of bottom topography in the so-called Spin-Up, where motion of a contained fluid is created by a sudden increase of rotation rate. Experiments are performed in a cylindrical container mounted on a rotating table and quantitative results are obtained with particle image velocimetry. Several horizontal length scales of topography (λ) are investigated, ranging from cases where λ is much smaller then the lateral extend of the experiment (R) to cases where λ is a fraction of R. We find that there is an optimal λ that creates maximum dissipation of kinetic energy. Depending on the length scale of the topography, kinetic energy is either dissipated in the boundary layer or in the bulk of the fluid. Two different phases of fluid motion are present: a starting flow in the from of solid rotation (phase I), which is later replaced by meso scale vortices on the length scale of bottom topography (phase II).

Numerical study of a thermally stratified flow of a tangent hyperbolic fluid induced by a stretching cylindrical surface

NASA Astrophysics Data System (ADS)

Ur Rehman, Khali; Ali Khan, Abid; Malik, M. Y.; Hussain, Arif

2017-09-01

The effects of temperature stratification on a tangent hyperbolic fluid flow over a stretching cylindrical surface are studied. The fluid flow is achieved by taking the no-slip condition into account. The mathematical modelling of the physical problem yields a nonlinear set of partial differential equations. These obtained partial differential equations are converted in terms of ordinary differential equations. Numerical investigation is done to identify the effects of the involved physical parameters on the dimensionless velocity and temperature profiles. In the presence of temperature stratification it is noticed that the curvature parameter makes both the fluid velocity and fluid temperature increase. In addition, positive variations in the thermal stratification parameter produce retardation with respect to the fluid flow, as a result the fluid temperature drops. The skin friction coefficient shows a decreasing nature for increasing value of both power law index and Weissenberg number, whereas the local Nusselt number is an increasing function of the Prandtl number, but opposite trends are found with respect to the thermal stratification parameter. The obtained results are validated by making a comparison with the existing literature which brings support to the presently developed model.

A modified fluid percussion device.

PubMed

Yamaki, T; Murakami, N; Iwamoto, Y; Yoshino, E; Nakagawa, Y; Ueda, S; Horikawa, J; Tsujii, T

1994-10-01

This report examines a modified fluid percussion device with specific improvements made to address deficiencies found in previously reported devices. These improvements include the use of a cylindrical saline reservoir made of stainless steel, placement of the reservoir in a 15-degree head-up position for the easy release of air bubbles, placement of the fluid flushing outlet and the pressure transducer close to the piston on the same plane, with both perpendicular to the direction of the piston, and adjustable reservoir volume to vary the waveform of the pressure pulse, and a metallic central injury screw secured to the animal's skull over the exposed dura. Using this device, midline fluid percussion (MFP) and lateral fluid percussion (LFP) injuries were performed in 70 rats. Histopathologic findings included diffuse axonal injury in the MFP model and cortical contusion in the LFP model. Survival rate was 41.4% in MFP animals and 100% in LFM animals when the device settings were 178 mm3 of the cylindrical reservoir and 50 degrees-60 degrees in height of the pendulum. Our results suggest that this modified fluid percussion device may offer significant improvements over previously reported fluid percussion models for use in experimental head injury.

Time-Dependent Thermally-Driven Interfacial Flows in Multilayered Fluid Structures

NASA Technical Reports Server (NTRS)

Haj-Hariri, Hossein; Borhan, A.

1996-01-01

A computational study of thermally-driven convection in multilayered fluid structures will be performed to examine the effect of interactions among deformable fluid-fluid interfaces on the structure of time-dependent flow in these systems. Multilayered fluid structures in two models configurations will be considered: the differentially heated rectangular cavity with a free surface, and the encapsulated cylindrical liquid bridge. An extension of a numerical method developed as part of our recent NASA Fluid Physics grant will be used to account for finite deformations of fluid-fluid interfaces.

An in vitro comparison of tracheostomy tube cuffs

PubMed Central

Maguire, Seamus; Haury, Frances; Jew, Korinne

2015-01-01

Introduction The Shiley™ Flexible adult tracheostomy tube with TaperGuard™ cuff has been designed through its geometry, materials, diameter, and wall thickness to minimize micro-aspiration of fluids past the cuff and to provide an effective air seal in the trachea while also minimizing the risk of excessive contact pressure on the tracheal mucosa. The cuff also has a deflated profile that may allow for easier insertion through the stoma site. This unique design is known as the TaperGuard™ cuff. The purpose of the observational, in vitro study reported here was to compare the TaperGuard™ taper-shaped cuff to a conventional high-volume low-pressure cylindrical-shaped cuff (Shiley™ Disposable Inner Cannula Tracheostomy Tube [DCT]) with respect to applied tracheal wall pressure, air and fluid sealing efficacy, and insertion force. Methods Three sizes of tracheostomy tubes with the two cuff types were placed in appropriately sized tracheal models and lateral wall pressure was measured via pressure-sensing elements on the inner surface. Fluid sealing performance was assessed by inflating the cuffs within the tracheal models (25 cmH2O), instilling water above the cuff, and measuring fluid leakage past the cuff. To measure air leak, tubes were attached to a test lung and ventilator, and leak was calculated by subtracting the average exhaled tidal volume from the average delivered tidal volume. A tensile test machine was used to measure insertion force for each tube with the cuff deflated to simulate clinical insertion through a stoma site. Results The average pressure exerted on the lateral wall of the model trachea was lower for the taper-shaped cuff than for the cylindrical cuff under all test conditions (P<0.05). The taper-shaped cuff also demonstrated a more even, lower pressure distribution along the lateral wall of the model trachea. The average air and fluid seal performance with the taper-shaped cuff was significantly improved, when compared to the cylindrical-shaped cuff, for each tube size tested (P<0.05). The insertion force for the taper-shaped cuff was ~40% less than that for the cylindrical-shaped cuff. Conclusion In a model trachea, the Shiley™ Flexible Adult tracheostomy tube with TaperGuard™ cuff, when compared to the Shiley™ Disposable Inner Cannula Tracheostomy tube with cylindrical cuff, exerted a lower average lateral wall pressure and a more evenly distributed pressure. In addition, it provided more effective fluid and air seals and required less force to insert. PMID:25960679

Modeling of composite coupling technology for oil-gas pipeline section resource-saving repair

NASA Astrophysics Data System (ADS)

Donkova, Irina; Yakubovskiy, Yuriy; Kruglov, Mikhail

2017-10-01

The article presents a variant of modeling and calculation of a main pipeline repair section with a composite coupling installation. This section is presented in a shape of a composite cylindrical shell. The aim of this work is mathematical modeling and study of main pipeline reconstruction section stress-strain state (SSS). There has been given a description of a structure deformation mathematical model. Based on physical relations of elasticity, integral characteristics of rigidity for each layer of a two-layer pipe section have been obtained. With the help of the systems of forces and moments which affect the layers differential equations for the first and second layer (pipeline and coupling) have been obtained. The study of the SSS has been conducted using the statements and hypotheses of the composite structures deformation theory with consideration of interlayer joint stresses. The relations to describe the work of the joint have been stated. Boundary conditions for each layer have been formulated. To describe the deformation of the composite coupling with consideration of the composite cylindrical shells theory a mathematical model in the form of a system of differential equations in displacements and boundary conditions has been obtained. Calculation of a two-layer cylindrical shell under the action of an axisymmetric load has been accomplished.

Virial series expansion and Monte Carlo studies of equation of state for hard spheres in narrow cylindrical pores

NASA Astrophysics Data System (ADS)

Mon, K. K.

2018-05-01

In this paper, the virial series expansion and constant pressure Monte Carlo method are used to study the longitudinal pressure equation of state for hard spheres in narrow cylindrical pores. We invoke dimensional reduction and map the model into an effective one-dimensional fluid model with interacting internal degrees of freedom. The one-dimensional model is extensive. The Euler relation holds, and longitudinal pressure can be probed with the standard virial series expansion method. Virial coefficients B2 and B3 were obtained analytically, and numerical quadrature was used for B4. A range of narrow pore widths (2 Rp) , Rp<(√{3 }+2 ) /4 =0.9330 ... (in units of the hard sphere diameter) was used, corresponding to fluids in the important single-file formations. We have also computed the virial pressure series coefficients B2', B3', and B4' to compare a truncated virial pressure series equation of state with accurate constant pressure Monte Carlo data. We find very good agreement for a wide range of pressures for narrow pores. These results contribute toward increasing the rather limited understanding of virial coefficients and the equation of state of hard sphere fluids in narrow cylindrical pores.

Assessment of the effects of azimuthal mode number perturbations upon the implosion processes of fluids in cylinders

NASA Astrophysics Data System (ADS)

Lindstrom, Michael

2017-06-01

Fluid instabilities arise in a variety of contexts and are often unwanted results of engineering imperfections. In one particular model for a magnetized target fusion reactor, a pressure wave is propagated in a cylindrical annulus comprised of a dense fluid before impinging upon a plasma and imploding it. Part of the success of the apparatus is a function of how axially-symmetric the final pressure pulse is upon impacting the plasma. We study a simple model for the implosion of the system to study how imperfections in the pressure imparted on the outer circumference grow due to geometric focusing. Our methodology entails linearizing the compressible Euler equations for mass and momentum conservation about a cylindrically symmetric problem and analysing the perturbed profiles at different mode numbers. The linearized system gives rise to singular shocks and through analysing the perturbation profiles at various times, we infer that high mode numbers are dampened through the propagation. We also study the Linear Klein-Gordon equation in the context of stability of linear cylindrical wave formation whereby highly oscillatory, bounded behaviour is observed in a far field solution.

Submersible sodium pump

DOEpatents

Brynsvold, Glen V.; Lopez, John T.; Olich, Eugene E.; West, Calvin W.

1989-01-01

An electromagnetic submerged pump has an outer cylindrical stator with an inner cylindrical conductive core for the submerged pumping of sodium in the cylindrical interstitial volume defined between the stator and core. The cylindrical interstitial volume is typically vertically oriented, and defines an inlet at the bottom and an outlet at the top. The outer stator generates upwardly conveyed toroidal magnetic fields, which fields convey preferably from the bottom of the pump to the top of the pump liquid sodium in the cold leg of a sodium cooled nuclear reactor. The outer cylindrical stator has a vertically disposed duct surrounded by alternately stacked layers of coil units and laminates.

Submersible sodium pump

DOEpatents

Brynsvold, G.V.; Lopez, J.T.; Olich, E.E.; West, C.W.

1989-11-21

An electromagnetic submerged pump has an outer cylindrical stator with an inner cylindrical conductive core for the submerged pumping of sodium in the cylindrical interstitial volume defined between the stator and core. The cylindrical interstitial volume is typically vertically oriented, and defines an inlet at the bottom and an outlet at the top. The outer stator generates upwardly conveyed toroidal magnetic fields, which fields convey preferably from the bottom of the pump to the top of the pump liquid sodium in the cold leg of a sodium cooled nuclear reactor. The outer cylindrical stator has a vertically disposed duct surrounded by alternately stacked layers of coil units and laminates. 14 figs.

Note: Device for obtaining volumetric, three-component velocity fields inside cylindrical cavities.

PubMed

Ramírez, G; Núñez, J; Hernández, G N; Hernández-Cruz, G; Ramos, E

2015-11-01

We describe a device designed and built to obtain the three-component, steady state velocity field in the whole volume occupied by a fluid in motion contained in a cavity with cylindrical walls. The prototype comprises a two-camera stereoscopic particle image velocimetry system mounted on a platform that rotates around the volume under analysis and a slip ring arrangement that transmits data from the rotating sensors to the data storage elements. Sample observations are presented for natural convection in a cylindrical container but other flows can be analyzed.

Hydrodynamic structures generated by a rotating magnetic field in a cylindrical vessel

NASA Astrophysics Data System (ADS)

Zibold, A. F.

2015-02-01

The hydrodynamic structures arising in a cylinder under the influence of a rotating magnetic field were considered, and the stability of a primary stationary flow in an infinitely long cylinder was investigated by linear approximation. The curves of neutral stability were obtained for a wide range of flow parameters and the calculations generated a single-vortex (in the radial direction) structure of Taylor’s vortices. The flow stability in the infinitely long cylinder was evaluated based on energy balance. The problem of three-dimensional stationary flow of a viscous incompressible conducting liquid induced by a rotating magnetic field in a cylindrical vessel of limited length was solved using an iteration method. The values of the parameters were found for which the iterative process still converges. Numerical experiment made it possible to investigate the arising spatial flow patterns and to track their evolution with changes in the flow parameters. Results of modelling showed the appearance of a three-dimensional structure of Taylor-type vortices in the middle portion of a sufficiently long vessel. The appearance of a double laminar boundary layer was demonstrated under certain conditions of azimuthal velocity distribution along the vessel height at the location of the end-wave vortex. This article was accepted for publication in Fluid Dynamics Research 2014 Vol 46, No 4; which was a special issue consisting of papers from the 5th International Symposium on Bifurcations in Fluid Dynamics. Due to an unfortunate error on the part of the journal, this article was not published with the other articles from this issue.

Understanding acoustic physics in oil and gas wellbores with the presence of ubiquitous geometric eccentricity

NASA Astrophysics Data System (ADS)

Liu, Yang; D'Angelo, Ralph M.; Choi, Gloria; Zhu, Lingchen; Bose, Sandip; Zeroug, Smaine

2018-04-01

Once an oil and gas wellbore has been drilled, steel casings and cement slurry are placed to ensure structural support, protection from fluid invasion, and most importantly to provide zonal isolation. The actual wellbore and string structure is rarely concentric but rather is often an eccentric one, especially in deviated boreholes. The term "eccentricity" is used to describe how off-center a casing string is within another pipe or the open-hole. In a typical double-string configuration, the inner casing is eccentered with respect to the outer string which itself is also eccentered within the cylindrical hole. The annuli may or may not be filled with solid cement, and the cement may have liquid-filled channels or be disbonded over localized azimuthal ranges. The complexity of wave propagation along axial intervals is significant in that multiple modes can be excited and detected with characteristics that are affected by the various parameters, including eccentering, in a non-linear fashion. A successful diagnosis of cement flaws largely relies on a thorough understanding of the complex acoustic modal information. The present study employs both modeling and experiments to fully understand the acoustic wave propagation in the complex, fluid-solid nested, cylindrically layered structures, with geometric eccentricities. The experimental results show excellent agreement with the theoretical predictions from newly developed, borehole acoustic modeling approaches. As such, it provides the basis for better understanding the operative wave physics and providing the means for effective inspection methodologies to assess well integrity and zonal isolation of oil wells.

CENTRIFUGE

DOEpatents

Rushing, F.C.

1960-09-01

A vibration damping mechanism for damping vibration forces occurring during the operation of a centrifuge is described. The vibration damping mechanism comprises a plurality of nested spaced cylindrical elements surrounding the rotating shaft of the centrifuge. Some of the elements are held substantially stationary while the others are held with respect to a pair of hearings spaced along the rotating shaft. A fluid is retained about the cylindrical elements.

Rotating reactor studies

NASA Technical Reports Server (NTRS)

Roberts, Glyn O.

1991-01-01

Undesired gravitational effects such as convection or sedimentation in a fluid can sometimes be avoided or decreased by the use of a closed chamber uniformly rotated about a horizontal axis. In a previous study, the spiral orbits of a heavy or buoyant particle in a uniformly rotating fluid were determined. The particles move in circles, and spiral in or out under the combined effects of the centrifugal force and centrifugal buoyancy. A optimization problem for the rotation rate of a cylindrical reactor rotated about its axis and containing distributed particles was formulated and solved. Related studies in several areas are addressed. A computer program based on the analysis was upgraded by correcting some minor errors, adding a sophisticated screen-and-printer graphics capability and other output options, and by improving the automation. The design, performance, and analysis of a series of experiments with monodisperse polystyrene latex microspheres in water were supported to test the theory and its limitations. The theory was amply confirmed at high rotation rates. However, at low rotation rates (1 rpm or less) the assumption of uniform solid-body rotation of the fluid became invalid, and there were increasingly strong secondary motions driven by variations in the mean fluid density due to variations in the particle concentration. In these tests the increase in the mean fluid density due to the particles was of order 0.015 percent. To a first approximation, these flows are driven by the buoyancy in a thin crescent-shaped depleted layer on the descending side of the rotating reactor. This buoyancy distribution is balanced by viscosity near the walls, and by the Coriolis force in the interior. A full analysis is beyond the scope of this study. Secondary flows are likely to be stronger for buoyant particles, which spiral in towards the neutral point near the rotation axis under the influence of their centrifugal buoyancy. This is because the depleted layer is thicker and extends all the way around the reactor.

Nozzle for electric dispersion reactor

DOEpatents

Sisson, Warren G.; Harris, Michael T.; Scott, Timothy C.; Basaran, Osman A.

1998-01-01

A nozzle for an electric dispersion reactor includes two coaxial cylindrical bodies, the inner one of the two delivering disperse phase fluid into a continuous phase fluid. A potential difference generated by a voltage source creates a dispersing electric field at the end of the inner electrode.

Nozzle for electric dispersion reactor

DOEpatents

Sisson, Warren G.; Harris, Michael T.; Scott, Timothy C.; Basaran, Osman A.

1996-01-01

A nozzle for an electric dispersion reactor includes two coaxial cylindrical bodies, the inner one of the two delivering disperse phase fluid into a continuous phase fluid. A potential difference generated by a voltage source creates a dispersing electric field at the end of the inner electrode.

QUASI-PML FOR WAVES IN CYLINDRICAL COORDINATES. (R825225)

EPA Science Inventory

We prove that the straightforward extension of Berenger's original perfectly matched layer (PML) is not reflectionless at a cylindrical interface in the continuum limit. A quasi-PLM is developed as an absorbing boundary condition (ABC) for the finite-difference time-domain method...

Hybrid Method for Power Control Simulation of a Single Fluid Plasma Thruster

NASA Astrophysics Data System (ADS)

Jaisankar, S.; Sheshadri, T. S.

2018-05-01

Propulsive plasma flow through a cylindrical-conical diverging thruster is simulated by a power controlled hybrid method to obtain the basic flow, thermodynamic and electromagnetic variables. Simulation is based on a single fluid model with electromagnetics being described by the equations of potential Poisson, Maxwell and the Ohm's law while the compressible fluid dynamics by the Navier Stokes in cylindrical form. The proposed method solved the electromagnetics and fluid dynamics separately, both to segregate the two prominent scales for an efficient computation and for the delivery of voltage controlled rated power. The magnetic transport is solved for steady state while fluid dynamics is allowed to evolve in time along with an electromagnetic source using schemes based on generalized finite difference discretization. The multistep methodology with power control is employed for simulating fully ionized propulsive flow of argon plasma through the thruster. Numerical solution shows convergence of every part of the solver including grid stability causing the multistep hybrid method to converge for a rated power delivery. Simulation results are reasonably in agreement with the reported physics of plasma flow in the thruster thus indicating the potential utility of this hybrid computational framework, especially when single fluid approximation of plasma is relevant.

Planar, free oscillations of a cylindrical fluid filament

NASA Astrophysics Data System (ADS)

Dasgupta, Ratul; Farsoiya, Palas Kumar

2017-11-01

A viscous cylindrical fluid filament of infinite axial extent is immersed in another viscous fluid at rest. We perturb the circular cross section of the filament with an azimuthal Fourier mode (exp(imθ) with wavenumber m real). Under/over damped free oscillations occur due to surface tension and we study these theoretically and through DNS. In the invisicd, irrotational approximation the dispersion relation for these oscillations was first obtained by Rayleigh (Proc. Roy. Soc. Lond., 29, 71, 1879) ignoring the inertia of the ambient fluid. Fyfe et al.. (J. Comp. Phys., 76, 349-384, 1988) subsequently included the inertia of the ambient fluid to the dispersion relation. We study the viscous correction to this relation, including viscosity of both the fluids. Unlike the inviscid dispersion relation which is an algebraic equation, the viscous dispersion relation turns out to be a transcendental equation. We study the roots of this equation on the complex frequency plane. In addition to the discrete spectrum, the viscous problem also has a continuous spectrum. The solution to the initial value problem which includes both, will be presented. Comparisons of analytical results with DNS results obtained from an in house developed VOF code, will be discussed.

The stability of a thin water layer over a rotating disk revisited

NASA Astrophysics Data System (ADS)

Poncet, Sébastien

2014-08-01

The flow driven by a rotating disk of a thin fluid layer in a fixed cylindrical casing is studied by direct numerical simulation and experimental flow visualizations. The characteristics of the flow are first briefly discussed but the focus of this work is to understand the transition to the primary instability. The primary bifurcation is 3D and appears as spectacular sharp-cornered polygonal patterns located along the shroud. The stability diagram is established experimentally in a ( Re, G plane, where G is the aspect ratio of the cavity and Re the rotational Reynolds number and confirmed numerically. The number of vortices scales well with the Ekman number based on the water depth, which confirms the existence of a Stewartson layer along the external cylinder. The critical mixed Reynolds number is found to be constant as in other rotating flows involving a shear-layer instability. Hysteresis cycles are observed highlighting the importance of the spin-up and spin-down processes. In some particular cases, a crossflow instability appears under the form of high azimuthal wave number spiral patterns, similar to those observed in a rotor-stator cavity with throughflow and coexists with the polygons. The DNS calculations confirm the experimental results under the flat free surface hypothesis.

Nozzle for electric dispersion reactor

DOEpatents

Sisson, W.G.; Harris, M.T.; Scott, T.C.; Basaran, O.A.

1996-04-02

A nozzle for an electric dispersion reactor includes two coaxial cylindrical bodies, the inner one of the two delivering disperse phase fluid into a continuous phase fluid. A potential difference generated by a voltage source creates a dispersing electric field at the end of the inner electrode. 5 figs.

Nozzle for electric dispersion reactor

DOEpatents

Sisson, W.G.; Harris, M.T.; Scott, T.C.; Basaran, O.A.

1998-06-02

A nozzle for an electric dispersion reactor includes two coaxial cylindrical bodies, the inner one of the two delivering disperse phase fluid into a continuous phase fluid. A potential difference generated by a voltage source creates a dispersing electric field at the end of the inner electrode. 5 figs.

High-resolution simulations of unstable cylindrical gravity currents undergoing wandering and splitting motions in a rotating system

NASA Astrophysics Data System (ADS)

Dai, Albert; Wu, Ching-Sen

2018-02-01

High-resolution simulations of unstable cylindrical gravity currents when wandering and splitting motions occur in a rotating system are reported. In this study, our attention is focused on the situation of unstable rotating cylindrical gravity currents when the ratio of Coriolis to inertia forces is larger, namely, 0.5 ≤ C ≤ 2.0, in comparison to the stable ones when C ≤ 0.3 as investigated previously by the authors. The simulations reproduce the major features of the unstable rotating cylindrical gravity currents observed in the laboratory, i.e., vortex-wandering or vortex-splitting following the contraction-relaxation motion, and good agreement is found when compared with the experimental results on the outrush radius of the advancing front and on the number of bulges. Furthermore, the simulations provide energy budget information which could not be attained in the laboratory. After the heavy fluid is released, the heavy fluid collapses and a contraction-relaxation motion is at work for approximately 2-3 revolutions of the system. During the contraction-relaxation motion of the heavy fluid, the unstable rotating cylindrical gravity currents behave similar to the stable ones. Towards the end of the contraction-relaxation motion, the dissipation rate in the system reaches a local minimum and a quasi-geostrophic equilibrium state is reached. After the quasi-geostrophic equilibrium state, vortex-wandering or vortex-splitting may occur depending on the ratio of Coriolis to inertia forces. The vortex-splitting process begins with non-axisymmetric bulges and, as the bulges grow, the kinetic energy increases at the expense of decreasing potential energy in the system. The completion of vortex-splitting is accompanied by a local maximum of dissipation rate and a local maximum of kinetic energy in the system. A striking feature of the unstable rotating cylindrical gravity currents is the persistent upwelling and downwelling motions, which are observed for both the vortex-wandering and vortex-splitting motions and were not previously documented for such flows. Depending on the Reynolds number, the bulges around the circumference of the unstable rotating cylindrical gravity currents may or may not develop into cutoff distinct circulations. The number of bulges is seen to be dependent on the ratio of Coriolis to inertia forces but independent of the Reynolds number for the range of Reynolds number considered in this study.

Oscillation Characteristics of Thermocapillary Convection in An Open Annular Pool

NASA Astrophysics Data System (ADS)

Duan, Li; Kang, Qi; Zhang, Di

2016-07-01

Temperature oscillation characteristics and free surface deformation are essential phenomena in fluids with free surface. We report experimental oscillatory behaviors for hydrothermal wave instability in thermocapillary-driven flow in an open annular pool of silicone oil. The annular pool is heated from the inner cylindrical wall with the radius 4mm and cooled at the outer wall with radius 20mm, and the depth of the silicone oil layer is in the range of 0.8mm-3mm.Temperature difference between the two sidewalls was increased gradually, and the flow will become unstable via a super critical temperature difference. In the present paper we used T-type thermocouple measuring the single-point temperature inside the liquid layer and captured the tiny micrometer wave signal through a high-precision laser displacement sensor. The critical temperature difference and critical Ma number of onset of oscillation have been obtained. We discussed the critical temperature difference and critical Marangoni number varies with the change of the depth of liquid layer, and the relationship between the temperature oscillation and surface oscillation has been discussed. Experimental results show that temperature oscillation and surface oscillation start almost at the same time with similar spectrum characteristic.

Turbulent Motion of Liquids in Hydraulic Resistances with a Linear Cylindrical Slide-Valve

PubMed Central

Velescu, C.; Popa, N. C.

2015-01-01

We analyze the motion of viscous and incompressible liquids in the annular space of controllable hydraulic resistances with a cylindrical linear slide-valve. This theoretical study focuses on the turbulent and steady-state motion regimes. The hydraulic resistances mentioned above are the most frequent type of hydraulic resistances used in hydraulic actuators and automation systems. To study the liquids' motion in the controllable hydraulic resistances with a linear cylindrical slide-valve, the report proposes an original analytic method. This study can similarly be applied to any other type of hydraulic resistance. Another purpose of this study is to determine certain mathematical relationships useful to approach the theoretical functionality of hydraulic resistances with magnetic controllable fluids as incompressible fluids in the presence of a controllable magnetic field. In this report, we established general analytic equations to calculate (i) velocity and pressure distributions, (ii) average velocity, (iii) volume flow rate of the liquid, (iv) pressures difference, and (v) radial clearance. PMID:26167532

Turbulent Motion of Liquids in Hydraulic Resistances with a Linear Cylindrical Slide-Valve.

PubMed

Velescu, C; Popa, N C

2015-01-01

We analyze the motion of viscous and incompressible liquids in the annular space of controllable hydraulic resistances with a cylindrical linear slide-valve. This theoretical study focuses on the turbulent and steady-state motion regimes. The hydraulic resistances mentioned above are the most frequent type of hydraulic resistances used in hydraulic actuators and automation systems. To study the liquids' motion in the controllable hydraulic resistances with a linear cylindrical slide-valve, the report proposes an original analytic method. This study can similarly be applied to any other type of hydraulic resistance. Another purpose of this study is to determine certain mathematical relationships useful to approach the theoretical functionality of hydraulic resistances with magnetic controllable fluids as incompressible fluids in the presence of a controllable magnetic field. In this report, we established general analytic equations to calculate (i) velocity and pressure distributions, (ii) average velocity, (iii) volume flow rate of the liquid, (iv) pressures difference, and (v) radial clearance.

Relationship between stirring rate and Reynolds number in the chaotically advected steady flow in a container with exactly counter-rotating lids

NASA Astrophysics Data System (ADS)

Lackey, Tahirih C.; Sotiropoulos, Fotis

2006-05-01

We solve numerically the three-dimensional incompressible Navier-Stokes equations to simulate the flow in a cylindrical container of aspect ratio one with exactly counter-rotating lids for a range of Reynolds numbers for which the flow is steady and three dimensional (300⩽Re⩽850). In agreement with linear stability results [C. Nore et al., J. Fluid Mech. 511, 45 (2004)] we find steady, axisymmetric solutions for Re <300. For Re >300 the equatorial shear layer becomes unstable to steady azimuthal modes and a complex vortical flow emerges, which consists of cat's eye radial vortices at the shear layer and azimuthally inclined axial vortices. Upon the onset of the three-dimensional instability the Lagrangian dynamics of the flow become chaotic. A striking finding of our work is that there is an optimal Reynolds number at which the stirring rate in the chaotically advected flow is maximized. Above this Reynolds number, the integrable (unmixed) part of the flow begins to grow and the stirring rate is shown conclusively to decline. This finding is explained in terms of and appears to support a recently proposed theory of chaotic advection [I. Mezić, J. Fluid Mech. 431, 347 (2001)]. Furthermore, the calculated rate of decay of the stirring rate with Reynolds numbers is consistent with the Re-1/2 upper bound predicted by the theory.

Data on the agitation of a viscous Newtonian fluid by radial impellers in a cylindrical tank.

PubMed

Ameur, Houari; Kamla, Youcef; Sahel, Djamel

2017-12-01

In this paper, the data assembled concerning the agitation of a Newtonian fluid in a cylindrical vessel is disclosed. The stirred vessel is not provided with baffles and has a flat-bottom. The data presents some information on the characteristics of two impellers: a six-blade Rushton turbine and a six-blade paddle impeller. The flow patterns generated by both impellers are depicted and compared. Also, the power required when changing the impeller rotational speed is given. The data summarized here via three-dimensional calculations of velocities and viscous dissipation in the whole volume of the tank provides additional knowledge for the best choice of impellers for each industrial process.

FLUID CONTACTOR APPARATUS

DOEpatents

Spence, R.; Streeton, R.J.W.

1956-04-17

The fluid contactor apparatus comprises a cylindrical column mounted co- axially and adapted to rotate within a cylindrical vessel, for the purpose of extracting a solute from am aqueous solution by means of an organic solvent. The column is particularly designed to control the vortex pattern so as to reduce the height of the vortices while, at the same time, the width of the annular radius in the radial direction between the vessel and column is less than half the radius of the column. A plurality of thin annular fins are spaced apart along the rotor approximately twice the radial dimension of the column such that two contrarotating substantially circular vortices are contained within each pair of fins as the column is rotated.

Presentation of computer code SPIRALI for incompressible, turbulent, plane and spiral grooved cylindrical and face seals

NASA Technical Reports Server (NTRS)

Walowit, Jed A.

1994-01-01

A viewgraph presentation is made showing the capabilities of the computer code SPIRALI. Overall capabilities of SPIRALI include: computes rotor dynamic coefficients, flow, and power loss for cylindrical and face seals; treats turbulent, laminar, Couette, and Poiseuille dominated flows; fluid inertia effects are included; rotor dynamic coefficients in three (face) or four (cylindrical) degrees of freedom; includes effects of spiral grooves; user definable transverse film geometry including circular steps and grooves; independent user definable friction factor models for rotor and stator; and user definable loss coefficients for sudden expansions and contractions.

Source Listings for Computer Code SPIRALI Incompressible, Turbulent Spiral Grooved Cylindrical and Face Seals

NASA Technical Reports Server (NTRS)

Walowit, Jed A.; Shapiro, Wibur

2005-01-01

This is the source listing of the computer code SPIRALI which predicts the performance characteristics of incompressible cylindrical and face seals with or without the inclusion of spiral grooves. Performance characteristics include load capacity (for face seals), leakage flow, power requirements and dynamic characteristics in the form of stiffness, damping and apparent mass coefficients in 4 degrees of freedom for cylindrical seals and 3 degrees of freedom for face seals. These performance characteristics are computed as functions of seal and groove geometry, load or film thickness, running and disturbance speeds, fluid viscosity, and boundary pressures.

Continuous pile discharging machine

DOEpatents

Smith, Phillips P.

1976-05-11

A device for discharging cartridges from tubes under fluid pressure includes a cylindrical housing adapted to be seated in a leak-tight manner on the end of one of the tubes, a chute depending from the cylindrical housing near the end seated on the end of the tube, a rotatable piston having a wrench on the forward end thereof disposed in the cylindrical housing and adapted to manipulate a plug in the end of the tube, and a telescopic hydraulic ram adapted to move the piston toward the plug. In addition the wrench contains a magnet which prevents inadvertent uncoupling of the wrench and the plug.

Deformation of a free interface pierced by a tilted cylinder

NASA Astrophysics Data System (ADS)

Raufaste, C.; Kirstetter, G.; Celestini, F.; Cox, S. J.

2012-07-01

We investigate the interaction between an infinite cylinder and a free fluid-fluid interface governed only by its surface tension. We study the deformation of an initially flat interface when it is deformed by the presence of a cylindrical object, tilted at an arbitrary angle, that the interface “totally wets”. Our simulations predict all significant quantities such as the interface shape, the position of the contact line, and the force exerted by the interface on the cylinder. These results are compared with an experimental study of the penetration of a soap film by a cylindrical liquid jet. This dynamic situation exhibits all the characteristics of a totally wetting interface. We show that whatever the inclination, the force is always perpendicular to the plane of the interface, and its amplitude diverges as the inclination angle increases. Such results should bring new insights in both fluid and solid mechanics, from animal locomotion to surface micro-processing.

Designing optimal nanofocusing with a gradient hyperlens

NASA Astrophysics Data System (ADS)

Shen, Lian; Prokopeva, Ludmila J.; Chen, Hongsheng; Kildishev, Alexander V.

2017-11-01

We report the design of a high-throughput gradient hyperbolic lenslet built with real-life materials and capable of focusing a beam into a deep sub-wavelength spot of λ/23. This efficient design is achieved through high-order transformation optics and circular effective-medium theory (CEMT), which are used to engineer the radially varying anisotropic artificial material based on the thin alternating cylindrical metal and dielectric layers. The radial gradient of the effective anisotropic optical constants allows for matching the impedances at the input and output interfaces, drastically improving the throughput of the lenslet. However, it is the use of the zeroth-order CEMT that enables the practical realization of a gradient hyperlens with realistic materials. To illustrate the importance of using the CEMT versus the conventional planar effective-medium theory (PEMT) for cylindrical anisotropic systems, such as our hyperlens, both the CEMT and PEMT are adopted to design gradient hyperlenses with the same materials and order of elemental layers. The CEMT- and PEMT-based designs show similar performance if the number of metal-dielectric binary layers is sufficiently large (9+ pairs) and if the layers are sufficiently thin. However, for the manufacturable lenses with realistic numbers of layers (e.g. five pairs) and thicknesses, the performance of the CEMT design continues to be practical, whereas the PEMT-based design stops working altogether. The accurate design of transformation optics-based layered cylindrical devices enabled by CEMT allow for a new class of robustly manufacturable nanophotonic systems, even with relatively thick layers of real-life materials.

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

NASA Astrophysics Data System (ADS)

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

2018-02-01

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

Convectively driven decadal zonal accelerations in Earth's fluid core

NASA Astrophysics Data System (ADS)

More, Colin; Dumberry, Mathieu

2018-04-01

Azimuthal accelerations of cylindrical surfaces co-axial with the rotation axis have been inferred to exist in Earth's fluid core on the basis of magnetic field observations and changes in the length-of-day. These accelerations have a typical timescale of decades. However, the physical mechanism causing the accelerations is not well understood. Scaling arguments suggest that the leading order torque averaged over cylindrical surfaces should arise from the Lorentz force. Decadal fluctuations in the magnetic field inside the core, driven by convective flows, could then force decadal changes in the Lorentz torque and generate zonal accelerations. We test this hypothesis by constructing a quasi-geostrophic model of magnetoconvection, with thermally driven flows perturbing a steady, imposed background magnetic field. We show that when the Alfvén number in our model is similar to that in Earth's fluid core, temporal fluctuations in the torque balance are dominated by the Lorentz torque, with the latter generating mean zonal accelerations. Our model reproduces both fast, free Alfvén waves and slow, forced accelerations, with ratios of relative strength and relative timescale similar to those inferred for the Earth's core. The temporal changes in the magnetic field which drive the time-varying Lorentz torque are produced by the underlying convective flows, shearing and advecting the magnetic field on a timescale associated with convective eddies. Our results support the hypothesis that temporal changes in the magnetic field deep inside Earth's fluid core drive the observed decadal zonal accelerations of cylindrical surfaces through the Lorentz torque.

Variation in bed level shear stress on surfaces sheltered by nonerodible roughness elements

NASA Astrophysics Data System (ADS)

Sutton, Stephen L. F.; McKenna-Neuman, Cheryl

2008-09-01

Direct bed level observations of surface shear stress, pressure gradient variability, turbulence intensity, and fluid flow patterns were carried out in the vicinity of cylindrical roughness elements mounted in a boundary layer wind tunnel. Paired corkscrew vortices shed from each of the elements result in elevated shear stress and increased potential for the initiation of particle transport within the far wake. While the size and shape of these trailing vortices change with the element spacing, they persist even for large roughness densities. Wake interference coincides with the impingement of the upwind horseshoe vortices upon one another at a point when their diameter approaches half the distance between the roughness elements. While the erosive capability of the horseshoe vortex has been suggested for a variety of settings, the present study shows that the fluid stress immediately beneath this coherent structure is actually small in comparison to that caused by compression of the incident flow as it is deflected around the element and attached vortex. Observations such as these are required for further refinement of models of stress partitioning on rough surfaces.

Highly Subwavelength, Superdirective Cylindrical Nanoantenna

NASA Astrophysics Data System (ADS)

Arslanagić, Samel; Ziolkowski, Richard W.

2018-06-01

A superdirective cylindrical nanoantenna is demonstrated with a multilayered cylindrical metamaterial-inspired structure. Targeting specific scattering coefficients for the dipole and higher-order modes, the ideal limit of needle radiation is demonstrated. A five-layer system is optimized to demonstrate its approach to the theoretical directivity bound. While the resulting structure is scalable to any frequency regime, its highly subwavelength overall size (λ0/10 ) takes advantage of combinations of positive and negative permittivity materials in the optical regime.

Generating Inviscid and Viscous Fluid Flow Simulations over a Surface Using a Quasi-simultaneous Technique

NASA Technical Reports Server (NTRS)

Sturdza, Peter (Inventor); Martins-Rivas, Herve (Inventor); Suzuki, Yoshifumi (Inventor)

2014-01-01

A fluid-flow simulation over a computer-generated surface is generated using a quasi-simultaneous technique. The simulation includes a fluid-flow mesh of inviscid and boundary-layer fluid cells. An initial fluid property for an inviscid fluid cell is determined using an inviscid fluid simulation that does not simulate fluid viscous effects. An initial boundary-layer fluid property a boundary-layer fluid cell is determined using the initial fluid property and a viscous fluid simulation that simulates fluid viscous effects. An updated boundary-layer fluid property is determined for the boundary-layer fluid cell using the initial fluid property, initial boundary-layer fluid property, and an interaction law. The interaction law approximates the inviscid fluid simulation using a matrix of aerodynamic influence coefficients computed using a two-dimensional surface panel technique and a fluid-property vector. An updated fluid property is determined for the inviscid fluid cell using the updated boundary-layer fluid property.

Vibration Power Flow In A Constrained Layer Damping Cylindrical Shell

NASA Astrophysics Data System (ADS)

Wang, Yun; Zheng, Gangtie

2012-07-01

In this paper, the vibration power flow in a constrained layer damping (CLD) cylindrical shell using wave propagation approach is investigated. The dynamic equations of the shell are derived with the Hamilton principle in conjunction with the Donnell shell assumption. With these equations, the dynamic responses of the system under a line circumferential cosine harmonic exciting force is obtained by employing the Fourier transform and the residue theorem. The vibration power flows inputted to the system and transmitted along the shell axial direction are both studied. The results show that input power flow varies with driving frequency and circumferential mode order, and the constrained damping layer can obviously restrict the exciting force from inputting power flow into the base shell especially for a thicker viscoelastic layer, a thicker or stiffer constraining layer (CL), and a higher circumferential mode order, can rapidly attenuate the vibration power flow transmitted along the base shell axial direction.

Effect of tracheal tube cuff shape on fluid leakage across the cuff: an in vitro study.

PubMed

Dave, M H; Frotzler, A; Spielmann, N; Madjdpour, C; Weiss, M

2010-10-01

This study compared the fluid leakage in the new 'tapered' shaped against the classic 'cylindrical' shaped tracheal tube cuffs when placed in different sized tracheas. The 7.5 mm internal diameter (ID) tracheal tube cuffs-Tapered Seal Guard (TSG), Standard Seal Guard (SSG), Hi-Lo, Microcuff, Ruesch, and Portex Profile-were compared in an in vitro apparatus. Vertical artificial tracheas with 16, 20, and 22 mm ID were intubated, 5 ml clear water was applied above the unlubricated tube cuffs, and fluid leakage was measured up to 60 min. Data of tapered vs non-tapered tube cuffs (16 observations) were compared for each tracheal diameter using the Mann-Whitney test. Median (range) fluid leakage (ml) at 60 min was 2.14 (0.05-4.88), 1.14 (0.00-4.84), and 0.13 (0.00-1.32), respectively, for 16, 20, and 22 mm tracheas in the TSG tube studies when compared with 4.58 (0.44-4.88), 2.21 (0.00-4.81), and 0.00 (0.00-4.81) in the SSG tube and 4.54 (1.54-4.82), 0.90 (0.00-4.49), and 4.85 (4.40-4.99) in the Microcuff tube studies. Leakage in all polyvinylchloride (PVC) tube cuffs was almost complete (5 ml) within 5 min (P<0.001). The tapered PU tube cuff was as effective as the cylindrical PU cuffs in smaller tracheal diameters and was more efficient than the cylindrical Microcuff PU tube cuff in larger tracheal diameter in preventing subglottic fluid leakage across the tube cuff tested in this in vitro study. PVC tube cuffs leaked much more and faster than PU cuffs.

Verification of long wavelength electromagnetic modes with a gyrokinetic-fluid hybrid model in the XGC code

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

Hager, Robert; Lang, Jianying; Chang, C. S.

As an alternative option to kinetic electrons, the gyrokinetic total-f particle-in-cell (PIC) code XGC1 has been extended to the MHD/fluid type electromagnetic regime by combining gyrokinetic PIC ions with massless drift-fluid electrons. Here, two representative long wavelength modes, shear Alfven waves and resistive tearing modes, are verified in cylindrical and toroidal magnetic field geometries.

Verification of long wavelength electromagnetic modes with a gyrokinetic-fluid hybrid model in the XGC code

DOE PAGES

Hager, Robert; Lang, Jianying; Chang, C. S.; ...

2017-05-24

As an alternative option to kinetic electrons, the gyrokinetic total-f particle-in-cell (PIC) code XGC1 has been extended to the MHD/fluid type electromagnetic regime by combining gyrokinetic PIC ions with massless drift-fluid electrons. Here, two representative long wavelength modes, shear Alfven waves and resistive tearing modes, are verified in cylindrical and toroidal magnetic field geometries.

Acoustic-Structure Interaction in Rocket Engines: Validation Testing

NASA Technical Reports Server (NTRS)

Davis, R. Benjamin; Joji, Scott S.; Parks, Russel A.; Brown, Andrew M.

2009-01-01

While analyzing a rocket engine component, it is often necessary to account for any effects that adjacent fluids (e.g., liquid fuels or oxidizers) might have on the structural dynamics of the component. To better characterize the fully coupled fluid-structure system responses, an analytical approach that models the system as a coupled expansion of rigid wall acoustic modes and in vacuo structural modes has been proposed. The present work seeks to experimentally validate this approach. To experimentally observe well-coupled system modes, the test article and fluid cavities are designed such that the uncoupled structural frequencies are comparable to the uncoupled acoustic frequencies. The test measures the natural frequencies, mode shapes, and forced response of cylindrical test articles in contact with fluid-filled cylindrical and/or annular cavities. The test article is excited with a stinger and the fluid-loaded response is acquired using a laser-doppler vibrometer. The experimentally determined fluid-loaded natural frequencies are compared directly to the results of the analytical model. Due to the geometric configuration of the test article, the analytical model is found to be valid for natural modes with circumferential wave numbers greater than four. In the case of these modes, the natural frequencies predicted by the analytical model demonstrate excellent agreement with the experimentally determined natural frequencies.

Thermal analysis of a reactive generalized Couette flow of power law fluids between concentric cylindrical pipes

NASA Astrophysics Data System (ADS)

Makinde, O. D.

2014-12-01

In this paper, the steady generalized axial Couette flow of Ostwald-de Waele power law reactive fluids between concentric cylindrical pipes is investigated. It is assumed that the outer cylinder is stationary and exchanges heat with the ambient surrounding following Newton's law of cooling, while the inner cylinder with isothermal surface is set in motion in the axial direction. The model nonlinear differential equations for the momentum and energy balance are obtained and tackled numerically using the shooting method coupled with the Runge-Kutta-Fehlberg integration technique. The effects of various embedded thermophysical parameters on the velocity and temperature fields including skin friction, Nusselt number and thermal criticality conditions are presented graphically and discussed quantitatively.

Normal stress effects on Knudsen flow

NASA Astrophysics Data System (ADS)

Eu, Byung Chan

2018-01-01

Normal stress effects are investigated on tube flow of a single-component non-Newtonian fluid under a constant pressure gradient in a constant temperature field. The generalized hydrodynamic equations are employed, which are consistent with the laws of thermodynamics. In the cylindrical tube flow configuration, the solutions of generalized hydrodynamic equations are exactly solvable and the flow velocity is obtained in a simple one-dimensional integral quadrature. Unlike the case of flow in the absence of normal stresses, the flow develops an anomaly in that the flow in the boundary layer becomes stagnant and the thickness of such a stagnant velocity boundary layer depends on the pressure gradient, the aspect ratio of the radius to the length of the tube, and the pressure (or density and temperature) at the entrance of the tube. The volume flow rate formula through the tube is derived for the flow. It generalizes the Knudsen flow rate formula to the case of a non-Newtonian stress tensor in the presence of normal stress differences. It also reduces to the Navier-Stokes theory formula in the low shear rate limit near equilibrium.

Measurements of Induced-Charge Electroosmotic Flow Around a Metallic Rod

NASA Astrophysics Data System (ADS)

Beskok, Ali; Canpolat, Cetin

2012-11-01

A cylindrical gold-coated stainless steel rod was positioned at the center of a straight microchannel connecting two fluid reservoirs on either end. The microchannel was filled with 1 mM KCl containing 0.5 micron diameter carboxylate-modified spherical particles. Induced-charge electro-osmotic (ICEO) flow occurred around the metallic rod under a sinusoidal AC electric field applied using two platinum electrodes. The ICEO flows around the metallic rod were measured using micro particle image velocimetry (micro-PIV) technique as functions of the AC electric field strength and frequency. The present study provides experimental data about ICEO flow in the weakly nonlinear limit of thin double layers, in which, the charging dynamics of the double layer cannot be presented analytically. Flow around the rod is quadrupolar, driving liquid towards the rod along the electric field and forcing it away from the rod in the direction perpendicular to the imposed electric field. The measured ICEO flow velocity is proportional to the square of the electric field strength, and depends on the applied AC frequency.

Prediction of Film Cooling Effectiveness on a Gas Turbine Blade Leading Edge Using ANN and CFD

NASA Astrophysics Data System (ADS)

Dávalos, J. O.; García, J. C.; Urquiza, G.; Huicochea, A.; De Santiago, O.

2018-05-01

In this work, the area-averaged film cooling effectiveness (AAFCE) on a gas turbine blade leading edge was predicted by employing an artificial neural network (ANN) using as input variables: hole diameter, injection angle, blowing ratio, hole and columns pitch. The database used to train the network was built using computational fluid dynamics (CFD) based on a two level full factorial design of experiments. The CFD numerical model was validated with an experimental rig, where a first stage blade of a gas turbine was represented by a cylindrical specimen. The ANN architecture was composed of three layers with four neurons in hidden layer and Levenberg-Marquardt was selected as ANN optimization algorithm. The AAFCE was successfully predicted by the ANN with a regression coefficient R2<0.99 and a root mean square error RMSE=0.0038. The ANN weight coefficients were used to estimate the relative importance of the input parameters. Blowing ratio was the most influential parameter with relative importance of 40.36 % followed by hole diameter. Additionally, by using the ANN model, the relationship between input parameters was analyzed.

Topology changes in a water-oil swirling flow

NASA Astrophysics Data System (ADS)

Carrión, Luis; Herrada, Miguel A.; Shtern, Vladimir N.

2017-03-01

This paper reveals the flow topology hidden in the experimental study by Fujimoto and Takeda ["Topology changes of the interface between two immiscible liquid layers by a rotating lid," Phys. Rev. E 80, 015304(R) (2009)]. Water and silicone oil fill a sealed vertical cylindrical container. The rotating top disk induces the meridional circulation and swirl of both fluids. As the rotation strength Reo increases, the interface takes shapes named, by the authors, hump, cusp, Mt. Fuji, and bell. Our numerical study reproduces the interface geometry and discloses complicated flow patterns. For example at Reo = 752, where the interface has the "Mt. Fuji" shape, the water motion has three bulk cells and the oil motion has two bulk cells. This topology helps explain the interface geometry. In addition, our study finds that the steady axisymmetric flow suffers from the shear-layer instability for Reo > 324, i.e., before the interface becomes remarkably deformed. The disturbance energy is concentrated in the water depth. This explains why the instability does not significantly affect the interface shape in the experiment.

Analytical model for vibration prediction of two parallel tunnels in a full-space

NASA Astrophysics Data System (ADS)

He, Chao; Zhou, Shunhua; Guo, Peijun; Di, Honggui; Zhang, Xiaohui

2018-06-01

This paper presents a three-dimensional analytical model for the prediction of ground vibrations from two parallel tunnels embedded in a full-space. The two tunnels are modelled as cylindrical shells of infinite length, and the surrounding soil is modelled as a full-space with two cylindrical cavities. A virtual interface is introduced to divide the soil into the right layer and the left layer. By transforming the cylindrical waves into the plane waves, the solution of wave propagation in the full-space with two cylindrical cavities is obtained. The transformations from the plane waves to cylindrical waves are then used to satisfy the boundary conditions on the tunnel-soil interfaces. The proposed model provides a highly efficient tool to predict the ground vibration induced by the underground railway, which accounts for the dynamic interaction between neighbouring tunnels. Analysis of the vibration fields produced over a range of frequencies and soil properties is conducted. When the distance between the two tunnels is smaller than three times the tunnel diameter, the interaction between neighbouring tunnels is highly significant, at times in the order of 20 dB. It is necessary to consider the interaction between neighbouring tunnels for the prediction of ground vibrations induced underground railways.

Contact interaction of thin-walled elements with an elastic layer and an infinite circular cylinder under torsion

NASA Astrophysics Data System (ADS)

Kanetsyan, E. G.; Mkrtchyan, M. S.; Mkhitaryan, S. M.

2018-04-01

We consider a class of contact torsion problems on interaction of thin-walled elements shaped as an elastic thin washer – a flat circular plate of small height – with an elastic layer, in particular, with a half-space, and on interaction of thin cylindrical shells with a solid elastic cylinder, infinite in both directions. The governing equations of the physical models of elastic thin washers and thin circular cylindrical shells under torsion are derived from the exact equations of mathematical theory of elasticity using the Hankel and Fourier transforms. Within the framework of the accepted physical models, the solution of the contact problem between an elastic washer and an elastic layer is reduced to solving the Fredholm integral equation of the first kind with a kernel representable as a sum of the Weber–Sonin integral and some integral regular kernel, while solving the contact problem between a cylindrical shell and solid cylinder is reduced to a singular integral equation (SIE). An effective method for solving the governing integral equations of these problems are specified.

Development of a cylindrical tracking detector with multichannel scintillation fibers and pixelated photon detector readout

NASA Astrophysics Data System (ADS)

Akazawa, Y.; Miwa, K.; Honda, R.; Shiozaki, T.; Chiga, N.

2015-07-01

We are developing a cylindrical tracking detector for a Σp scattering experiment in J-PARC with scintillation fibers and the Pixelated Photon Detector (PPD) readout, which is called as cylindrical fiber tracker (CFT), in order to reconstruct trajectories of charged particles emitted inside CFT. CFT works not only as a tracking detector but also a particle identification detector from energy deposits. A prototype CFT consisting of two straight layers and one spiral layer was constructed. About 1100 scintillation fibers with a diameter of 0.75 mm (Kuraray SCSF-78 M) were used. Each fiber signal was read by Multi-Pixel Photon Counter (MPPC, HPK S10362-11-050P, 1×1 mm2, 400 pixels) fiber by fiber. MPPCs were handled with Extended Analogue Silicon Photomultipliers Integrated ReadOut Chip (EASIROC) boards, which were developed for the readout of a large number of MPPCs. The energy resolution of one layer was 28% for a 70 MeV proton where the energy deposit in fibers was 0.7 MeV.

Inferring regional vertical crustal velocities from averaged relative sea level trends: A proof of concept

NASA Astrophysics Data System (ADS)

Bâki Iz, H.; Shum, C. K.; Zhang, C.; Kuo, C. Y.

2017-11-01

We report the design of a high-throughput gradient hyperbolic lenslet built with real-life materials and capable of focusing a beam into a deep sub-wavelength spot of λ/23. This efficient design is achieved through high-order transformation optics and circular effective-medium theory (CEMT), which are used to engineer the radially varying anisotropic artificial material based on the thin alternating cylindrical metal and dielectric layers. The radial gradient of the effective anisotropic optical constants allows for matching the impedances at the input and output interfaces, drastically improving the throughput of the lenslet. However, it is the use of the zeroth-order CEMT that enables the practical realization of a gradient hyperlens with realistic materials. To illustrate the importance of using the CEMT versus the conventional planar effective-medium theory (PEMT) for cylindrical anisotropic systems, such as our hyperlens, both the CEMT and PEMT are adopted to design gradient hyperlenses with the same materials and order of elemental layers. The CEMT- and PEMT-based designs show similar performance if the number of metal-dielectric binary layers is sufficiently large (9+ pairs) and if the layers are sufficiently thin. However, for the manufacturable lenses with realistic numbers of layers (e.g. five pairs) and thicknesses, the performance of the CEMT design continues to be practical, whereas the PEMT-based design stops working altogether. The accurate design of transformation optics-based layered cylindrical devices enabled by CEMT allow for a new class of robustly manufacturable nanophotonic systems, even with relatively thick layers of real-life materials.

Recirculation cells for granular flow in cylindrical rotating tumblers

NASA Astrophysics Data System (ADS)

D'Ortona, Umberto; Thomas, Nathalie; Lueptow, Richard M.

2018-05-01

To better understand the velocity field and flowing layer structure, we have performed a detailed discrete element method study of the flow of monodisperse particles in a partially filled three-dimensional cylindrical rotating tumblers. Similar to what occurs near the poles in spherical and conical tumblers, recirculation cells (secondary flows) develop near the flat endwalls of a cylindrical tumbler in which particles near the surface drift axially toward the endwall, while particles deeper in the flowing layer drift axially toward the midlength of the tumbler. Another recirculation cell with the opposite sense develops next to each endwall recirculation cell, extending to the midlength of the tumbler. For a long enough tumbler, each endwall cell is about one quarter of the tumbler diameter in length. Endwall cells are insensitive to tumbler length and relatively insensitive to rotation speed (so long as the flowing layer remains flat and continuously flowing) or fill level (from 25% to 50% full). However, for shorter tumblers (0.5 to 1.0 length/diameter aspect ratio) the endwall cell size does not change much, while center cells reduce their size and eventually disappear for the shortest tumblers. For longer tumblers (length/diameter aspect ratio larger than 2), a stagnation zone appears in between the central cells. These results provide insight into the mixing of monodisperse particles in rotating cylindrical tumblers as well as the frictional effects of the tumbler endwalls.

Observation of turbulent-driven shear flow in a cylindrical laboratory plasma device.

PubMed

Holland, C; Yu, J H; James, A; Nishijima, D; Shimada, M; Taheri, N; Tynan, G R

2006-05-19

An azimuthally symmetric radially sheared plasma fluid flow is observed to spontaneously form in a cylindrical magnetized helicon plasma device with no external sources of momentum input. A turbulent momentum conservation analysis shows that this shear flow is sustained by the Reynolds stress generated by collisional drift turbulence in the device. The results provide direct experimental support for the basic theoretical picture of drift-wave-shear-flow interactions.

Beam heated linear theta-pinch device for producing hot plasmas

DOEpatents

Bohachevsky, Ihor O.

1981-01-01

A device for producing hot plasmas comprising a single turn theta-pinch coil, a fast discharge capacitor bank connected to the coil, a fuel element disposed along the center axis of the coil, a predetermined gas disposed within the theta-pinch coil, and a high power photon, electron or ion beam generator concentrically aligned to the theta-pinch coil. Discharge of the capacitor bank generates a cylindrical plasma sheath within the theta-pinch coil which heats the outer layer of the fuel element to form a fuel element plasma layer. The beam deposits energy in either the cylindrical plasma sheath or the fuel element plasma layer to assist the implosion of the fuel element to produce a hot plasma.

Sonar Imaging of Elastic Fluid-Filled Cylindrical Shells.

NASA Astrophysics Data System (ADS)

Dodd, Stirling Scott

1995-01-01

Previously a method of describing spherical acoustic waves in cylindrical coordinates was applied to the problem of point source scattering by an elastic infinite fluid -filled cylindrical shell (S. Dodd and C. Loeffler, J. Acoust. Soc. Am. 97, 3284(A) (1995)). This method is applied to numerically model monostatic oblique incidence scattering from a truncated cylinder by a narrow-beam high-frequency imaging sonar. The narrow beam solution results from integrating the point source solution over the spatial extent of a line source and line receiver. The cylinder truncation is treated by the method of images, and assumes that the reflection coefficient at the truncation is unity. The scattering form functions, calculated using this method, are applied as filters to a narrow bandwidth, high ka pulse to find the time domain scattering response. The time domain pulses are further processed and displayed in the form of a sonar image. These images compare favorably to experimentally obtained images (G. Kaduchak and C. Loeffler, J. Acoust. Soc. Am. 97, 3289(A) (1995)). The impact of the s_{ rm o} and a_{rm o} Lamb waves is vividly apparent in the images.

Investigation of Perforated Convergent-divergent Diffusers with Initial Boundary Layer

NASA Technical Reports Server (NTRS)

Weinstein, Maynard I

1950-01-01

An experimental investigation was made at Mach number 1.90 of the performance of a series of perforated convergent-divergent supersonic diffusers operating with initial boundary layer, which was induced and controlled by lengths of cylindrical inlets affixed to the diffusers. Supercritical mass-flow and peak total-pressure recoveries were decreased slightly by use of the longest inlets (4 inlet diameters in length). Combinations of cylindrical inlets, perforated diffusers, and subsonic diffuser were evaluated as simulated wind tunnels having second throats. Comparisons with noncontracted configurations of similar scale indicated conservatively computed power reductions of 25 percent.

Users' Manual for Computer Code SPIRALI Incompressible, Turbulent Spiral Grooved Cylindrical and Face Seals

NASA Technical Reports Server (NTRS)

Walowit, Jed A.; Shapiro, Wilbur

2005-01-01

The SPIRALI code predicts the performance characteristics of incompressible cylindrical and face seals with or without the inclusion of spiral grooves. Performance characteristics include load capacity (for face seals), leakage flow, power requirements and dynamic characteristics in the form of stiffness, damping and apparent mass coefficients in 4 degrees of freedom for cylindrical seals and 3 degrees of freedom for face seals. These performance characteristics are computed as functions of seal and groove geometry, load or film thickness, running and disturbance speeds, fluid viscosity, and boundary pressures. A derivation of the equations governing the performance of turbulent, incompressible, spiral groove cylindrical and face seals along with a description of their solution is given. The computer codes are described, including an input description, sample cases, and comparisons with results of other codes.

Dynamics of charged viscous dissipative cylindrical collapse with full causal approach

NASA Astrophysics Data System (ADS)

Shah, S. M.; Abbas, G.

2017-11-01

The aim of this paper is to investigate the dynamical aspects of a charged viscous cylindrical source by using the Misner approach. To this end, we have considered the more general charged dissipative fluid enclosed by the cylindrical symmetric spacetime. The dissipative nature of the source is due to the presence of dissipative variables in the stress-energy tensor. The dynamical equations resulting from such charged cylindrical dissipative source have been coupled with the causal transport equations for heat flux, shear and bulk viscosity, in the context of the Israel-Steward theory. In this case, we have the considered Israel-Steward transportation equations without excluding the thermodynamics viscous/heat coupling coefficients. The results are compared with the previous works in which such coefficients were excluded and viscosity variables do not satisfy the casual transportation equations.

Ion-acoustic solitons do not exist in cylindrical and spherical geometries

NASA Astrophysics Data System (ADS)

Sheridan, T. E.

2017-09-01

We investigate the time evolution of one-dimensional, compressive, ion acoustic solitary waves for planar, cylindrical, and spherical geometries in a plasma of cold fluid ions and Boltzmann electrons. For cylindrical and spherical geometries, we show that inward (outward) going solitary waves cannot be localized (i.e., always have a tail) since the effect of a unipolar velocity perturbation is to shift ions inward (outward) to smaller (larger) radii, thereby increasing (decreasing) the local ion density. That is, there are no quasi-particle soliton states in the cylindrical and spherical cases. These results are confirmed and expanded using a plasma simulation for the cylindrical case. We initialize the system with an inward propagating planar soliton. We find supersonic solitary waves which increase in speed as they near the origin, while the wave amplitude increases as r-1/2. All solitary waves develop the predicted tail, but for larger amplitudes, the tail is unstable and evolves into an acoustic wave train.

Cylindrical optical resonators: fundamental properties and bio-sensing characteristics

NASA Astrophysics Data System (ADS)

Khozeymeh, Foroogh; Razaghi, Mohammad

2018-04-01

In this paper, detailed theoretical analysis of cylindrical resonators is demonstrated. As illustrated, these kinds of resonators can be used as optical bio-sensing devices. The proposed structure is analyzed using an analytical method based on Lam's approximation. This method is systematic and has simplified the tedious process of whispering-gallery mode (WGM) wavelength analysis in optical cylindrical biosensors. By this method, analysis of higher radial orders of high angular momentum WGMs has been possible. Using closed-form analytical equations, resonance wavelengths of higher radial and angular order WGMs of TE and TM polarization waves are calculated. It is shown that high angular momentum WGMs are more appropriate for bio-sensing applications. Some of the calculations are done using a numerical non-linear Newton method. A perfect match of 99.84% between the analytical and the numerical methods has been achieved. In order to verify the validity of the calculations, Meep simulations based on the finite difference time domain (FDTD) method are performed. In this case, a match of 96.70% between the analytical and FDTD results has been obtained. The analytical predictions are in good agreement with other experimental work (99.99% match). These results validate the proposed analytical modelling for the fast design of optical cylindrical biosensors. It is shown that by extending the proposed two-layer resonator structure analyzing scheme, it is possible to study a three-layer cylindrical resonator structure as well. Moreover, by this method, fast sensitivity optimization in cylindrical resonator-based biosensors has been possible. Sensitivity of the WGM resonances is analyzed as a function of the structural parameters of the cylindrical resonators. Based on the results, fourth radial order WGMs, with a resonator radius of 50 μm, display the most bulk refractive index sensitivity of 41.50 (nm/RIU).

Three-step labyrinth seal for high-performance turbomachines

NASA Technical Reports Server (NTRS)

Hendricks, Robert C.

1987-01-01

A three-step labyrinth seal with 12, 11, and 10 labyrinth teeth per step, respectively, was tested under static (nonrotating) conditions. The configuration represented the seal for a high-performance turbopump (e.g., the space shuttle main engine fuel pump). The test data included critical mass flux and pressure profiles over a wide range of fluid conditions at concentric, partially eccentric, and fully eccentric seal positions. The seal mass fluxes (leakage rates) were lower over the entire range of fluid conditions tested than those for data collected for similar straight and three-step cylindrical seals, and this conformed somewhat to expectations. However, the pressure profiles for the eccentric positions indicated little, if any, direct stiffness for this configuration in contrast to significant direct stiffness reported for the straight and three-step cylindrical seals over the range of test conditions. Seal dynamics depend on geometric configuration, inlet and exit parameters, fluid phase, and rotation. The method of corresponding states was applied to the mass flux data, which were found to have a pressure dependency for helium.

Bi-orthogonality relations for fluid-filled elastic cylindrical shells: Theory, generalisations and application to construct tailored Green's matrices

NASA Astrophysics Data System (ADS)

Ledet, Lasse S.; Sorokin, Sergey V.

2018-03-01

The paper addresses the classical problem of time-harmonic forced vibrations of a fluid-filled cylindrical shell considered as a multi-modal waveguide carrying infinitely many waves. The forced vibration problem is solved using tailored Green's matrices formulated in terms of eigenfunction expansions. The formulation of Green's matrix is based on special (bi-)orthogonality relations between the eigenfunctions, which are derived here for the fluid-filled shell. Further, the relations are generalised to any multi-modal symmetric waveguide. Using the orthogonality relations the transcendental equation system is converted into algebraic modal equations that can be solved analytically. Upon formulation of Green's matrices the solution space is studied in terms of completeness and convergence (uniformity and rate). Special features and findings exposed only through this modal decomposition method are elaborated and the physical interpretation of the bi-orthogonality relation is discussed in relation to the total energy flow which leads to derivation of simplified equations for the energy flow components.

Report of the Working Group on Aerodynamics of Aircraft Afterbody.

DTIC Science & Technology

1986-06-01

14 I 21 2.1.71 Addy A.L. Experimeftal-Theoretical Correlation of Supersonic Jet-on Base Pressure for Cylindrical Afterbodies. J. Aircraft, Vol. 7, No...An Improved Experimental-Theoretical Base Pressure Cor- Addy A.L. relation for Conical and Cylindrical Afterbodies with Agrell J. Centered Propulsive...2.1.92 Carri~re P. Effet d’une Injection de Fluide dans l’Eau-Morte sur les Conditions de Recollement d’un Ecoulement Plan Supersonique. Comptes

First and second sound in cylindrically trapped gases.

PubMed

Bertaina, G; Pitaevskii, L; Stringari, S

2010-10-08

We investigate the propagation of density and temperature waves in a cylindrically trapped gas with radial harmonic confinement. Starting from two-fluid hydrodynamic theory we derive effective 1D equations for the chemical potential and the temperature which explicitly account for the effects of viscosity and thermal conductivity. Differently from quantum fluids confined by rigid walls, the harmonic confinement allows for the propagation of both first and second sound in the long wavelength limit. We provide quantitative predictions for the two sound velocities of a superfluid Fermi gas at unitarity. For shorter wavelengths we discover a new surprising class of excitations continuously spread over a finite interval of frequencies. This results in a nondissipative damping in the response function which is analytically calculated in the limiting case of a classical ideal gas.

Coupled mixed-field laminate theory and finite element for smart piezoelectric composite shell structures

NASA Technical Reports Server (NTRS)

Saravanos, Dimitris A.

1996-01-01

Mechanics for the analysis of laminated composite shells with piezoelectric actuators and sensors are presented. A new mixed-field laminate theory for piezoelectric shells is formulated in curvilinear coordinates which combines single-layer assumptions for the displacements and a layerwise representation for the electric potential. The resultant coupled governing equations for curvilinear piezoelectric laminates are described. Structural mechanics are subsequently developed and an 8-node finite-element is formulated for the static and dynamic analysis of adaptive composite structures of general laminations containing piezoelectric layers. Evaluations of the method and comparisons with reported results are presented for laminated piezoelectric-composite plates, a closed cylindrical shell with a continuous piezoceramic layer and a laminated composite semi-circular cantilever shell with discrete cylindrical piezoelectric actuators and/or sensors.

Fiber-Type Random Laser Based on a Cylindrical Waveguide with a Disordered Cladding Layer.

PubMed

Zhang, Wei Li; Zheng, Meng Ya; Ma, Rui; Gong, Chao Yang; Yang, Zhao Ji; Peng, Gang Ding; Rao, Yun Jiang

2016-05-25

This letter reports a fiber-type random laser (RL) which is made from a capillary coated with a disordered layer at its internal surface and filled with a gain (laser dye) solution in the core region. This fiber-type optical structure, with the disordered layer providing randomly scattered light into the gain region and the cylindrical waveguide providing confinement of light, assists the formation of random lasing modes and enables a flexible and efficient way of making random lasers. We found that the RL is sensitive to laser dye concentration in the core region and there exists a fine exponential relationship between the lasing intensity and particle concentration in the gain solution. The proposed structure could be a fine platform of realizing random lasing and random lasing based sensing.

Finite element analysis of stress transfer mechanism from matrix to the fiber in SWCN reinforced nanocomposites

NASA Astrophysics Data System (ADS)

Günay, E.

2017-02-01

This study defined as micromechanical finite element (FE) approach examining the stress transfer mechanism in single-walled carbon nanotube (SWCN) reinforced composites. In the modeling, 3D unit-cell method was evaluated. Carbon nanotube reinforced composites were modeled as three layers which comprises CNT, interface and matrix material. Firstly; matrix, fiber and interfacial materials all together considered as three layered cylindrical nanocomposite. Secondly, the cylindrical matrix material was assumed to be isotropic and also considered as a continuous medium. Then, fiber material was represented with zigzag type SWCNs. Finally, SWCN was combined with the elastic medium by using springs with different constants. In the FE modeling of SWCN reinforced composite model springs were modeled by using ANSYS spring damper element COMBIN14. The developed interfacial van der Waals interaction effects between the continuous matrix layer and the carbon nanotube fiber layer were simulated by applying these various spring stiffness values. In this study, the layered composite cylindrical FE model was presented as the equivalent mechanical properties of SWCN structures in terms of Young's modulus. The obtained results and literature values were presented and discussed. Figures, 16, 17, and 18 of the original article PDF file, as supplied to AIP Publishing, were affected by a PDF-processing error. Consequently, a solid diamond symbol appeared instead of a Greek tau on the y axis labels for these three figures. This article was updated on 17 March 2017 to correct the PDF-processing error, with the scientific content remaining unchanged.

Surface tension and long range corrections of cylindrical interfaces

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

Bourasseau, E.; Malfreyt, P.; Ghoufi, A., E-mail: aziz.ghoufi@univ-rennes1.fr

2015-12-21

The calculation of the surface tension of curved interfaces has been deeply investigated from molecular simulation during this last past decade. Recently, the thermodynamic Test-Area (TA) approach has been extended to the calculation of surface tension of curved interfaces. In the case of the cylindrical vapour-liquid interfaces of water and Lennard-Jones fluids, it was shown that the surface tension was independent of the curvature of the interface. In addition, the surface tension of the cylindrical interface is higher than that of the planar interface. Molecular simulations of cylindrical interfaces have been so far performed (i) by using a shifted potential,more » (ii) by means of large cutoff without periodic boundary conditions, or (iii) by ignoring the long range corrections to the surface tension due to the difficulty to estimate them. Indeed, unlike the planar interfaces there are no available operational expressions to consider the tail corrections to the surface tension of cylindrical interfaces. We propose here to develop the long range corrections of the surface tension for cylindrical interfaces by using the non-exponential TA (TA2) method. We also extend the formulation of the Mecke-Winkelmann corrections initially developed for planar surfaces to cylindrical interfaces. We complete this study by the calculation of the surface tension of cylindrical surfaces of liquid tin and copper using the embedded atom model potentials.« less

Bell-Plesset effects in Rayleigh-Taylor instability of finite-thickness spherical and cylindrical shells

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

Velikovich, A. L.; Schmit, P. F.

Bell-Plesset (BP) effects account for the influence of global convergence or divergence of the fluid flow on the evolution of the interfacial perturbations embedded in the flow. The development of the Rayleigh-Taylor instability in radiation-driven spherical capsules and magnetically-driven cylindrical liners necessarily includes a significant contribution from BP effects due to the time dependence of the radius, velocity, and acceleration of the unstable surfaces or interfaces. An analytical model is presented that, for an ideal incompressible fluid and small perturbation amplitudes, exactly evaluates the BP effects in finite-thickness shells through acceleration and deceleration phases. The time-dependent dispersion equations determining themore » “instantaneous growth rate” are derived. It is demonstrated that by integrating this approximate growth rate over time, one can accurately evaluate the number of perturbation e-foldings during the inward acceleration phase of the implosion. In the limit of small shell thickness, exact thin-shell perturbation equations and approximate thin-shell dispersion equations are obtained, generalizing the earlier results [E. G. Harris, Phys. Fluids 5, 1057 (1962); E. Ott, Phys. Rev. Lett. 29, 1429 (1972); A. B. Bud'ko et al., Phys. Fluids B 2, 1159 (1990)].« less

Bell-Plesset effects in Rayleigh-Taylor instability of finite-thickness spherical and cylindrical shells

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

Velikovich, A. L.; Schmit, P. F.

Bell-Plesset (BP) effects account for the influence of global convergence or divergence of the fluid flow on the evolution of the interfacial perturbations embedded in the flow. The development of the Rayleigh-Taylor instability in radiation-driven spherical capsules and magnetically-driven cylindrical liners necessarily includes a significant contribution from BP effects due to the time dependence of the radius, velocity, and acceleration of the unstable surfaces or interfaces. An analytical model is presented that, for an ideal incompressible fluid and small perturbation amplitudes, exactly evaluates the BP effects in finite-thickness shells through acceleration and deceleration phases. The time-dependent dispersion equations determining themore » “instantaneous growth rate” are derived. It is demonstrated that by integrating this approximate growth rate over time, one can accurately evaluate the number of perturbation e-foldings during the inward acceleration phase of the implosion. As a result, in the limit of small shell thickness, exact thin-shell perturbationequations and approximate thin-shell dispersion equations are obtained, generalizing the earlier results [E. G. Harris, Phys. Fluids 5, 1057 (1962); E. Ott, Phys. Rev. Lett. 29, 1429 (1972); A. B. Bud'ko et al., Phys. Fluids B 2, 1159 (1990)].« less

A 3D-CFD code for accurate prediction of fluid flows and fluid forces in seals

NASA Technical Reports Server (NTRS)

Athavale, M. M.; Przekwas, A. J.; Hendricks, R. C.

1994-01-01

Current and future turbomachinery requires advanced seal configurations to control leakage, inhibit mixing of incompatible fluids and to control the rotodynamic response. In recognition of a deficiency in the existing predictive methodology for seals, a seven year effort was established in 1990 by NASA's Office of Aeronautics Exploration and Technology, under the Earth-to-Orbit Propulsion program, to develop validated Computational Fluid Dynamics (CFD) concepts, codes and analyses for seals. The effort will provide NASA and the U.S. Aerospace Industry with advanced CFD scientific codes and industrial codes for analyzing and designing turbomachinery seals. An advanced 3D CFD cylindrical seal code has been developed, incorporating state-of-the-art computational methodology for flow analysis in straight, tapered and stepped seals. Relevant computational features of the code include: stationary/rotating coordinates, cylindrical and general Body Fitted Coordinates (BFC) systems, high order differencing schemes, colocated variable arrangement, advanced turbulence models, incompressible/compressible flows, and moving grids. This paper presents the current status of code development, code demonstration for predicting rotordynamic coefficients, numerical parametric study of entrance loss coefficients for generic annular seals, and plans for code extensions to labyrinth, damping, and other seal configurations.

Bell-Plesset effects in Rayleigh-Taylor instability of finite-thickness spherical and cylindrical shells

DOE PAGES

Velikovich, A. L.; Schmit, P. F.

2015-12-28

Bell-Plesset (BP) effects account for the influence of global convergence or divergence of the fluid flow on the evolution of the interfacial perturbations embedded in the flow. The development of the Rayleigh-Taylor instability in radiation-driven spherical capsules and magnetically-driven cylindrical liners necessarily includes a significant contribution from BP effects due to the time dependence of the radius, velocity, and acceleration of the unstable surfaces or interfaces. An analytical model is presented that, for an ideal incompressible fluid and small perturbation amplitudes, exactly evaluates the BP effects in finite-thickness shells through acceleration and deceleration phases. The time-dependent dispersion equations determining themore » “instantaneous growth rate” are derived. It is demonstrated that by integrating this approximate growth rate over time, one can accurately evaluate the number of perturbation e-foldings during the inward acceleration phase of the implosion. As a result, in the limit of small shell thickness, exact thin-shell perturbationequations and approximate thin-shell dispersion equations are obtained, generalizing the earlier results [E. G. Harris, Phys. Fluids 5, 1057 (1962); E. Ott, Phys. Rev. Lett. 29, 1429 (1972); A. B. Bud'ko et al., Phys. Fluids B 2, 1159 (1990)].« less

Bell-Plesset effects in Rayleigh-Taylor instability of finite-thickness spherical and cylindrical shells

NASA Astrophysics Data System (ADS)

Velikovich, A. L.; Schmit, P. F.

2015-12-01

Bell-Plesset (BP) effects account for the influence of global convergence or divergence of the fluid flow on the evolution of the interfacial perturbations embedded in the flow. The development of the Rayleigh-Taylor instability in radiation-driven spherical capsules and magnetically-driven cylindrical liners necessarily includes a significant contribution from BP effects due to the time dependence of the radius, velocity, and acceleration of the unstable surfaces or interfaces. An analytical model is presented that, for an ideal incompressible fluid and small perturbation amplitudes, exactly evaluates the BP effects in finite-thickness shells through acceleration and deceleration phases. The time-dependent dispersion equations determining the "instantaneous growth rate" are derived. It is demonstrated that by integrating this approximate growth rate over time, one can accurately evaluate the number of perturbation e-foldings during the inward acceleration phase of the implosion. In the limit of small shell thickness, exact thin-shell perturbation equations and approximate thin-shell dispersion equations are obtained, generalizing the earlier results [E. G. Harris, Phys. Fluids 5, 1057 (1962); E. Ott, Phys. Rev. Lett. 29, 1429 (1972); A. B. Bud'ko et al., Phys. Fluids B 2, 1159 (1990)].

Cylindrical acoustic levitator/concentrator

DOEpatents

Kaduchak, Gregory; Sinha, Dipen N.

2002-01-01

A low-power, inexpensive acoustic apparatus for levitation and/or concentration of aerosols and small liquid/solid samples having particulates up to several millimeters in diameter in air or other fluids is described. It is constructed from a commercially available, hollow cylindrical piezoelectric crystal which has been modified to tune the resonance frequency of the breathing mode resonance of the crystal to that of the interior cavity of the cylinder. When the resonance frequency of the interior cylindrical cavity is matched to the breathing mode resonance of the cylindrical piezoelectric transducer, the acoustic efficiency for establishing a standing wave pattern in the cavity is high. The cylinder does not require accurate alignment of a resonant cavity. Water droplets having diameters greater than 1 mm have been levitated against the force of gravity using; less than 1 W of input electrical power. Concentration of aerosol particles in air is also demonstrated.

Electro-Mechanical Coaxial Valve

NASA Technical Reports Server (NTRS)

Patterson, Paul R (Inventor)

2004-01-01

Coaxial valves usually contain only one moving part. It has not been easy, then, to provide for electric motor actuation. Many actuators being proposed involve designs which lead to bulky packages. The key facing those improving coaxial valves is the provision of suitable linear actuation. The valve herein indudes a valve housing with a flow channel there-through. Arranged in the flow channel is a closing body. In alignment with the closing body is a ball screw actuator which includes a ball nut and a cylindrical screw. The ball nut sounds a threaded portion of the cylindrical screw. The cylindrical screw is provided with a passageway there-through through which fluid flows. The cylindrical screw is disposed in the flow channel to become a control tube adapted to move toward and away from the valve seat. To rotate the ball nut an actuating drive is employed driven by a stepper motor.

Method and apparatus for production of subsea hydrocarbon formations

DOEpatents

Blandford, Joseph W.

1994-01-01

A well tender system for controlling, separating, storing and offloading well fluids produced from subsea hydrocarbon formations. The system comprises a vertically aligned series of tethered cylindrical tanks which are torsionally stabilized by flexible catenary production riser and export riser bundles, and serviced by separate catenary pipe bundles. Piles are secured to the seabed, each pile assembly being pivotally connected to a lower rigid tendon, which is in turn connected to tendons arranged about the periphery of the interconnected cylindrical tanks.

Method and apparatus for production of subsea hydrocarbon formations

DOEpatents

Blandford, Joseph W.

1992-01-01

A well tender system for controlling, separating, storing and offloading well fluids produced from subsea hydrocarbon formations. The system comprises a vertically aligned series of tethered cylindrical tanks which are torsionally stabilized by flexible catenary production riser and expert riser bundles, and serviced by separate catenary pipe bundles. Piles are secured to the seabed, each pile assembly being pivotally connected to a lower rigid tendon, which is in turn connected to tendons arranged about the periphery of the interconnected cylindrical tanks.

Heat pipes for use in a magnetic field

DOEpatents

Werner, Richard W.; Hoffman, Myron A.

1983-01-01

A heat pipe configuration for use in a magnetic field environment of a fusion reactor. Heat pipes for operation in a magnetic field when liquid metal working fluids are used are optimized by flattening of the heat pipes having an unobstructed annulus which significantly reduces the adverse side region effect of the prior known cylindrically configured heat pipes. The flattened heat pipes operating in a magnetic field can remove 2--3 times the heat as a cylindrical heat pipe of the same cross sectional area.

Generating Inviscid and Viscous Fluid-Flow Simulations over an Aircraft Surface Using a Fluid-Flow Mesh

NASA Technical Reports Server (NTRS)

Rodriguez, David L. (Inventor); Sturdza, Peter (Inventor)

2013-01-01

Fluid-flow simulation over a computer-generated aircraft surface is generated using inviscid and viscous simulations. A fluid-flow mesh of fluid cells is obtained. At least one inviscid fluid property for the fluid cells is determined using an inviscid fluid simulation that does not simulate fluid viscous effects. A set of intersecting fluid cells that intersects the aircraft surface are identified. One surface mesh polygon of the surface mesh is identified for each intersecting fluid cell. A boundary-layer prediction point for each identified surface mesh polygon is determined. At least one boundary-layer fluid property for each boundary-layer prediction point is determined using the at least one inviscid fluid property of the corresponding intersecting fluid cell and a boundary-layer simulation that simulates fluid viscous effects. At least one updated fluid property for at least one fluid cell is determined using the at least one boundary-layer fluid property and the inviscid fluid simulation.

Ekman-Hartmann layer in a magnetohydrodynamic Taylor-Couette flow

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

Szklarski, Jacek; Ruediger, Guenther

2007-12-15

We study magnetic effects induced by rigidly rotating plates enclosing a cylindrical magnetohydrodynamic (MHD) Taylor-Couette flow at the finite aspect ratio H/D=10. The fluid confined between the cylinders is assumed to be liquid metal characterized by small magnetic Prandtl number, the cylinders are perfectly conducting, an axial magnetic field is imposed with Hartmann number Ha{approx_equal}10, and the rotation rates correspond to Reynolds numbers of order 10{sup 2}-10{sup 3}. We show that the end plates introduce, besides the well-known Ekman circulation, similar magnetic effects which arise for infinite, rotating plates, horizontally unbounded by any walls. In particular, there exists the Hartmannmore » current, which penetrates the fluid, turns in the radial direction, and together with the applied magnetic field gives rise to a force. Consequently, the flow can be compared with a Taylor-Dean flow driven by an azimuthal pressure gradient. We analyze the stability of such flows and show that the currents induced by the plates can give rise to instability for the considered parameters. When designing a MHD Taylor-Couette experiment, special care must be taken concerning the vertical magnetic boundaries so that they do not significantly alter the rotational profile.« less

Design-Optimization Of Cylindrical, Layered Composite Structures Using Efficient Laminate Parameterization

NASA Astrophysics Data System (ADS)

Monicke, A.; Katajisto, H.; Leroy, M.; Petermann, N.; Kere, P.; Perillo, M.

2012-07-01

For many years, layered composites have proven essential for the successful design of high-performance space structures, such as launchers or satellites. A generic cylindrical composite structure for a launcher application was optimized with respect to objectives and constraints typical for space applications. The studies included the structural stability, laminate load response and failure analyses. Several types of cylinders (with and without stiffeners) were considered and optimized using different lay-up parameterizations. Results for the best designs are presented and discussed. The simulation tools, ESAComp [1] and modeFRONTIER [2], employed in the optimization loop are elucidated and their value for the optimization process is explained.

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

PubMed

Hlushak, Stepan

2018-01-03

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

Verification of long wavelength electromagnetic modes with a gyrokinetic-fluid hybrid model in the XGC code

PubMed Central

Lang, Jianying; Ku, S.; Chen, Y.; Parker, S. E.; Adams, M. F.

2017-01-01

As an alternative option to kinetic electrons, the gyrokinetic total-f particle-in-cell (PIC) code XGC1 has been extended to the MHD/fluid type electromagnetic regime by combining gyrokinetic PIC ions with massless drift-fluid electrons analogous to Chen and Parker [Phys. Plasmas 8, 441 (2001)]. Two representative long wavelength modes, shear Alfvén waves and resistive tearing modes, are verified in cylindrical and toroidal magnetic field geometries. PMID:29104419

The conical stent in coronary artery improves hemodynamics compared with the traditional cylindrical stent.

PubMed

Yu, Yi; Zhou, Yujie; Ma, Qian; Jia, Shuo; Wu, Sijing; Sun, Yan; Liu, Xiaoli; Zhao, Yingxin; Liu, Yuyang; Shi, Dongmei

2017-01-15

This study sought to explore the efficacy of the conical stent implantation in the coronary artery by comparing the effects of cylindrical and conical stents on wall shear stress (WSS) and velocity of flow and fractional flow reserve (FFR). The traditional cylindrical stent currently used in the percutaneous coronary intervention (PCI) has a consistent diameter, which does not match the physiological change of the coronary artery. On the contrary, as a new patent, the conical stent with tapering lumen is consistent with the physiological change of vascular diameter. However, the effect of the conical stent implantation on the coronary hemodynamics remains unclear. The coronary artery, artery stenosis and two stent models were established by Solidworks software. All models were imported into the computational fluid dynamics (CFD) software ANSYS ICEM-CFD to establish the fluid model. After the boundary conditions were set, CFD analysis was proceeded to compare the effects of two stent implantation on the change of WSS, velocity of flow and FFR. Hemodynamic indexes including FFR, blood flow velocity distribution (BVD) and WSS were improved by either the cylindrical or the conical stent implantation. However, after the conical stent implantation, the change of FFR seemed to be slower and more homogenous; the blood flow velocity was more appropriate without any obvious blood stagnation and direction changes; the WSS after the conical stent implantation was uniform from the proximal to distal side of the stent. Compared with the cylindrical stent, the conical stent implantation in the coronary artery can make the changes of vascular hemodynamic more closer to the physiological condition, which can reduce the incidence of intra-stent restenosis and thrombosis, thus making it more suitable for PCI therapy. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Structural transitions and guest/host complexing of liquid crystal helical nanofilaments induced by nanoconfinement.

PubMed

Kim, Hanim; Ryu, Seong Ho; Tuchband, Michael; Shin, Tae Joo; Korblova, Eva; Walba, David M; Clark, Noel A; Yoon, Dong Ki

2017-02-01

A lamellar liquid crystal (LC) phase of certain bent-core mesogenic molecules can be grown in a manner that generates a single chiral helical nanofilament in each of the cylindrical nanopores of an anodic aluminum oxide (AAO) membrane. By introducing guest molecules into the resulting composite chiral nanochannels, we explore the structures and functionality of the ordered guest/host LC complex, verifying the smectic-like positional order of the fluidic nematic LC phase, which is obtained by the combination of the LC organization and the nanoporous AAO superstructure. The guest nematic LC 4'- n -pentyl-4-cyanobiphenyl is found to form a distinctive fluid layered ordered LC complex at the nanofilament/guest interface with the host 1,3-phenylene bis[4-(4-nonyloxyphenyliminomethyl)benzoate], where this interface contacts the AAO cylinder wall. Filament growth form is strongly influenced by mixture parameters and pore dimensions.

Nonlinear spin-up in a circular cylinder

NASA Astrophysics Data System (ADS)

van de Konijnenberg, J. A.; van Heijst, G. J. F.

1995-12-01

Nonlinear spin-up in a circular cylindrical tank is investigated experimentally and compared with the Wedemeyer model. The experiments were performed with water, using tracer particles floating at the free surface in order to visualize the flow field. The experimentally determined vorticity profiles show differences from the Wedemeyer model that indicate the need for an improved estimation of the Ekman pumping on a finite domain. In particular, the Wedemeyer model appears to be inaccurate in the region close to the sidewall. The vorticity field in a spin-down experiment can be reproduced very well by using numerical data of Rogers and Lance for the Ekman suction of an unbounded rotating fluid over a nonrotating plate. However, a more general use of the data of Rogers and Lance on a bounded domain is shown to be inadequate because this would lead to a violation of mass conservation of the Ekman layer.

Structural transitions and guest/host complexing of liquid crystal helical nanofilaments induced by nanoconfinement

PubMed Central

Kim, Hanim; Ryu, Seong Ho; Tuchband, Michael; Shin, Tae Joo; Korblova, Eva; Walba, David M.; Clark, Noel A.; Yoon, Dong Ki

2017-01-01

A lamellar liquid crystal (LC) phase of certain bent-core mesogenic molecules can be grown in a manner that generates a single chiral helical nanofilament in each of the cylindrical nanopores of an anodic aluminum oxide (AAO) membrane. By introducing guest molecules into the resulting composite chiral nanochannels, we explore the structures and functionality of the ordered guest/host LC complex, verifying the smectic-like positional order of the fluidic nematic LC phase, which is obtained by the combination of the LC organization and the nanoporous AAO superstructure. The guest nematic LC 4′-n-pentyl-4-cyanobiphenyl is found to form a distinctive fluid layered ordered LC complex at the nanofilament/guest interface with the host 1,3-phenylene bis[4-(4-nonyloxyphenyliminomethyl)benzoate], where this interface contacts the AAO cylinder wall. Filament growth form is strongly influenced by mixture parameters and pore dimensions. PMID:28246642

An experimental study of the transient regime to fluidized chimney in a granular medium

NASA Astrophysics Data System (ADS)

Philippe, Pierre; Mena, Sarah; Brunier-Coulin, Florian; Curtis, Jennifer

2017-06-01

Localized fluidization within a granular packing along an almost cylindrical chimney is observed when an upward fluid-flow, injected through a small port diameter, exceeds a critical flow-rate. Once this threshold reached, a fluidized area is first initiated in the close vicinity of the injection hole before gradually growing upward to the top surface of the granular layer. In this work, we present an experimental investigation specifically dedicated to the kinetics of chimney fluidization in an immersed granular bed. Two different transient regimes are identified depending on wether the expansion of the fluidized area is rather fast and regular, reaching the final chimney state typically in less than 10 seconds, or, on the contrary, slow and very progressively accelerated, giving rise to transient duration up to 1 hour or even more. Some systematic investigations allow to propose several empirical scaling relations for the kinetics of chimney fluidization in the fast regular regime.

The nonlinear dynamics of a spacecraft coupled to the vibration of a contained fluid

NASA Technical Reports Server (NTRS)

Peterson, Lee D.; Crawley, Edward F.; Hansman, R. John

1988-01-01

The dynamics of a linear spacecraft mode coupled to a nonlinear low gravity slosh of a fluid in a cylindrical tank is investigated. Coupled, nonlinear equations of motion for the fluid-spacecraft dynamics are derived through an assumed mode Lagrangian method. Unlike linear fluid slosh models, this nonlinear slosh model retains two fundamental slosh modes and three secondary modes. An approximate perturbation solution of the equations of motion indicates that the nonlinear coupled system response involves fluid-spacecraft modal resonances not predicted by either a linear, or a nonlinear, uncoupled slosh analysis. Experimental results substantiate the analytical predictions.

Instability patterns in a miscible core annular flow

NASA Astrophysics Data System (ADS)

D'Olce, Marguerite; Martin, Jerome; Rakotomalala, Nicole; Salin, Dominique; Talon, Laurent

2006-11-01

Laboratoire FAST, batiment 502, campus universitaire, 91405 Orsay Cedex (France). Experiments are performed with two miscible fluids of equal density but different viscosities. The fluids are injected co-currently and concentrically into a cylindrical pipe. The so-obtained base state is an axisymmetric parallel flow, for which the ratio of the flow rates of the two fluids monitors the relative amount (and so the radius) of the fluids. Depending on this relative amount and on the total flow rate of the fluids, unstable axisymmetric patterns such as mushrooms and pearls are observed. We delineate the diagram of occurrence of the two patterns and characterize the instabilities.

A study of self-propelled elastic cylindrical micro-swimmers using modeling and computation

NASA Astrophysics Data System (ADS)

Shi, Lingling; Čanić, Sunčica; Quaini, Annalisa; Pan, Tsorng-Whay

2016-06-01

We study propulsion of micro-swimmers in 3D creeping flow. The swimmers are assumed to be made of elastic cylindrical hollow tubes. The swimming is generated by the contractions of the tube's elastic membrane walls producing a traveling wave in the form of a ;step-function; traversing the swimmer from right to left, propelling the swimmer from left to right. The problem is motivated by medical applications such as drug delivery. The influence of several non-dimensional design parameters on the velocity of the swimmer is investigated, including the swimmer aspect ratio, and the amplitude of the traveling wave relative to the swimmer radius. An immersed boundary method based on a finite element method approach is successfully combined with an elastic spring network model to simulate the two-way fluid-structure interaction coupling between the elastic cylindrical tube and the flow of a 3D viscous, incompressible fluid. To gain a deeper insight into the influence of various parameters on the swimmer speed, a reduced 1D fluid-structure interaction model was derived and validated. It was found that fast swimmers are those with large tube aspect ratios, and with the amplitude of the traveling wave which is roughly 50% of the reference swimmer radius. It was shown that the speed of our ;optimal swimmer; is around 1.5 swimmer lengths per second, which is at the top of the class of all currently manufactured micro-swimmers swimming in low Reynolds number flows (Re =10-6), reported in [11].

Piston-Driven Fluid Ejectors In Silicon Mems

DOEpatents

Galambos, Paul C.; Benavides, Gilbert L.; Jokiel, Jr., Bernhard; Jakubczak II, Jerome F.

2005-05-03

A surface-micromachined fluid-ejection apparatus is disclosed which utilizes a piston to provide for the ejection of jets or drops of a fluid (e.g. for ink-jet printing). The piston, which is located at least partially inside a fluid reservoir, is moveable into a cylindrical fluid-ejection chamber connected to the reservoir by a microelectromechanical (MEM) actuator which is located outside the reservoir. In this way, the reservoir and fluid-ejection chamber can be maintained as electric-field-free regions thereby allowing the apparatus to be used with fluids that are electrically conductive or which may react or break down in the presence of a high electric field. The MEM actuator can comprise either an electrostatic actuator or a thermal actuator.

Fem Formulation of Heat Transfer in Cylindrical Porous Medium

NASA Astrophysics Data System (ADS)

Azeem; Khaleed, H. M. T.; Soudagar, Manzoor Elahi M.

2017-08-01

Heat transfer in porous medium can be derived from the fundamental laws of flow in porous region ass given by Henry Darcy. The fluid flow and energy transport inside the porous medium can be described with the help of momentum and energy equations. The heat transfer in cylindrical porous medium differs from its counterpart in radial and axial coordinates. The present work is focused to discuss the finite element formulation of heat transfer in cylindrical porous medium. The basic partial differential equations are derived using Darcy law which is the converted into a set of algebraic equations with the help of finite element method. The resulting equations are solved by matrix method for two solution variables involved in the coupled equations.

Fluid oscillation in the Drop Tower

NASA Technical Reports Server (NTRS)

Kaukler, William F.

1988-01-01

An interfluid meniscus oscillates within a cylindrical container when suddenly released from earth's gravity and taken into a microgravity environment. Oscillations damp out from energy dissipative mechanisms such as viscosity and interfacial friction. Damping out of the oscillations by the latter mechanism is affected by the nature of the interfacial junction between the fluid-fluid interface and the container wall. Perfluoromethylcyclohexane and isopropanol in glass were the materials used for the experiment. The wetting condition of the fluids against the wall changes at the critical wetting transition temperature. This change in wetting causes a change in the damping characteristics.

Preliminary SAGE Simulations of Volcanic Jets Into a Stratified Atmosphere

NASA Astrophysics Data System (ADS)

Peterson, A. H.; Wohletz, K. H.; Ogden, D. E.; Gisler, G. R.; Glatzmaier, G. A.

2007-12-01

The SAGE (SAIC Adaptive Grid Eulerian) code employs adaptive mesh refinement in solving Eulerian equations of complex fluid flow desirable for simulation of volcanic eruptions. The goal of modeling volcanic eruptions is to better develop a code's predictive capabilities in order to understand the dynamics that govern the overall behavior of real eruption columns. To achieve this goal, we focus on the dynamics of underexpended jets, one of the fundamental physical processes important to explosive eruptions. Previous simulations of laboratory jets modeled in cylindrical coordinates were benchmarked with simulations in CFDLib (Los Alamos National Laboratory), which solves the full Navier-Stokes equations (includes viscous stress tensor), and showed close agreement, indicating that adaptive mesh refinement used in SAGE may offset the need for explicit calculation of viscous dissipation.We compare gas density contours of these previous simulations with the same initial conditions in cylindrical and Cartesian geometries to laboratory experiments to determine both the validity of the model and the robustness of the code. The SAGE results in both geometries are within several percent of the experiments for position and density of the incident (intercepting) and reflected shocks, slip lines, shear layers, and Mach disk. To expand our study into a volcanic regime, we simulate large-scale jets in a stratified atmosphere to establish the code's ability to model a sustained jet into a stable atmosphere.

Rapid, conformal gas-phase formation of silica (SiO2) nanotubes from water condensates

NASA Astrophysics Data System (ADS)

Bae, Changdeuck; Kim, Hyunchul; Yang, Yunjeong; Yoo, Hyunjun; Montero Moreno, Josep M.; Bachmann, Julien; Nielsch, Kornelius; Shin, Hyunjung

2013-06-01

An innovative atomic layer deposition (ALD) concept, with which nanostructures of water condensates with high aspect ratio at equilibrium in cylindrical nanopores can be transformed uniformly into silica (SiO2) at near room temperature and ambient pressure, has been demonstrated for the first time. As a challenging model system, we first prove the conversion of cylindrical water condensates in porous alumina membranes to silica nanotubes (NTs) by introducing SiCl4 as a metal reactant without involving any catalytic reaction. Surprisingly, the water NTs reproducibly transformed into silica NTs, where the wall thickness of the silica NTs deposited per cycle was found to be limited by the amount of condensed water, and it was on the orders of ten nanometers per cycle (i.e., over 50 times faster than that of conventional ALD). More remarkably, the reactions only took place for 10-20 minutes or less without vacuum-related equipment. The thickness of initially adsorbed water layers in cylindrical nanopores was indirectly estimated from the thickness of formed SiO2 layers. With systematic experimental designs, we tackle the classical Kelvin equation in the nanosized pores, and the role of van der Waals forces in the nanoscale wetting phenomena, which is a long-standing issue lacking experimental insight. Moreover, we show that the present strategy is likely generalized to other oxide systems such as TiO2. Our approach opens up a new avenue for ultra-simple preparation of porous oxides and allows for the room temperature formation of dielectric layers toward organic electronic and photovoltaic applications.An innovative atomic layer deposition (ALD) concept, with which nanostructures of water condensates with high aspect ratio at equilibrium in cylindrical nanopores can be transformed uniformly into silica (SiO2) at near room temperature and ambient pressure, has been demonstrated for the first time. As a challenging model system, we first prove the conversion of cylindrical water condensates in porous alumina membranes to silica nanotubes (NTs) by introducing SiCl4 as a metal reactant without involving any catalytic reaction. Surprisingly, the water NTs reproducibly transformed into silica NTs, where the wall thickness of the silica NTs deposited per cycle was found to be limited by the amount of condensed water, and it was on the orders of ten nanometers per cycle (i.e., over 50 times faster than that of conventional ALD). More remarkably, the reactions only took place for 10-20 minutes or less without vacuum-related equipment. The thickness of initially adsorbed water layers in cylindrical nanopores was indirectly estimated from the thickness of formed SiO2 layers. With systematic experimental designs, we tackle the classical Kelvin equation in the nanosized pores, and the role of van der Waals forces in the nanoscale wetting phenomena, which is a long-standing issue lacking experimental insight. Moreover, we show that the present strategy is likely generalized to other oxide systems such as TiO2. Our approach opens up a new avenue for ultra-simple preparation of porous oxides and allows for the room temperature formation of dielectric layers toward organic electronic and photovoltaic applications. Electronic supplementary information (ESI) available: TEM gallery of silica NTs under different experimental conditions, detailed calculation of estimating the thickness of condensed water and Hamaker constants, and a comparison of processing times. See DOI: 10.1039/c3nr00906h

Cylindrical effects on Richtmyer-Meshkov instability for arbitrary Atwood numbers in weakly nonlinear regime

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

Liu, W. H.; He, X. T.; LCP, Institute of Applied Physics and Computational Mathematics, Beijing 100088

2012-07-15

When an incident shock collides with a corrugated interface separating two fluids of different densities, the interface is prone to Richtmyer-Meshkov instability (RMI). Based on the formal perturbation expansion method as well as the potential flow theory, we present a simple method to investigate the cylindrical effects in weakly nonlinear RMI with the transmitted and reflected cylindrical shocks by considering the nonlinear corrections up to fourth order. The cylindrical results associated with the material interface show that the interface expression consists of two parts: the result in the planar system and that from the cylindrical effects. In the limit ofmore » the cylindrical radius tending to infinity, the cylindrical results can be reduced to those in the planar system. Our explicit results show that the cylindrical effects exert an inward velocity on the whole perturbed interface, regardless of bubbles or spikes of the interface. On the one hand, outgoing bubbles are constrained and ingoing spikes are accelerated for different Atwood numbers (A) and mode numbers k'. On the other hand, for ingoing bubbles, when |A|k'{sup 3/2} Less-Than-Or-Equivalent-To 1, bubbles are considerably accelerated especially at the small |A| and k'; otherwise, bubbles are decelerated. For outgoing spikes, when |A|k' Greater-Than-Or-Equivalent-To 1, spikes are dramatically accelerated especially at large |A| and k'; otherwise, spikes are decelerated. Furthermore, the cylindrical effects have a significant influence on the amplitudes of the ingoing spike and bubble for large k'. Thus, it should be included in applications where the cylindrical effects play a role, such as inertial confinement fusion ignition target design.« less

Separating attoliter-sized compartments using fluid pore-spanning lipid bilayers.

PubMed

Lazzara, Thomas D; Carnarius, Christian; Kocun, Marta; Janshoff, Andreas; Steinem, Claudia

2011-09-27

Anodic aluminum oxide (AAO) is a porous material having aligned cylindrical compartments with 55-60 nm diameter pores, and being several micrometers deep. A protocol was developed to generate pore-spanning fluid lipid bilayers separating the attoliter-sized compartments of the nanoporous material from the bulk solution, while preserving the optical transparency of the AAO. The AAO was selectively functionalized by silane chemistry to spread giant unilamellar vesicles (GUVs) resulting in large continuous membrane patches covering the pores. Formation of fluid single lipid bilayers through GUV rupture could be readily observed by fluorescence microscopy and further supported by conservation of membrane surface area, before and after GUV rupture. Fluorescence recovery after photobleaching gave low immobile fractions (5-15%) and lipid diffusion coefficients similar to those found for bilayers on silica. The entrapment of molecules within the porous underlying cylindrical compartments, as well as the exclusion of macromolecules from the nanopores, demonstrate the barrier function of the pore-spanning membranes and could be investigated in three-dimensions using confocal laser scanning fluorescence imaging. © 2011 American Chemical Society

A study of fluid-structure problems

NASA Astrophysics Data System (ADS)

Lam, Dennis Kang-Por

The stability of structures with and without fluid load is investigated. A method is developed for determining the fluid load in terms of added structural mass. Finite element methods are employed to study the buckling of a cylindrical shell under axial compression and liquid storage tanks under hydrodynamic load. Both linear and nonlinear analyses are performed. Diamond modes are found to be the possible postbuckling shapes of the cylindrical shell. Local buckling including elephant-foot buckle and diamond buckle are found for the liquid storage tank models. Comparison between the linear and nonlinear results indicates a substantial difference in buckling mode shapes, though the buckling loads are close to each other. The method for determining the hydrodynamic mass is applied to the impeller stage of a centrifugal pump. The method is based on a linear perturbation technique which assumes that the disturbance in the flow boundaries and velocities caused by the motion of the structure is small. A potential method is used to estimate the velocity flow field. The hydrodynamic mass is then obtained by calculating the total force which results from the pressure induced by a perturbation of the structure.

Scale interaction and arrangement in a turbulent boundary layer perturbed by a wall-mounted cylindrical element

NASA Astrophysics Data System (ADS)

Tang, Zhanqi; Jiang, Nan

2018-05-01

This study reports the modifications of scale interaction and arrangement in a turbulent boundary layer perturbed by a wall-mounted circular cylinder. Hot-wire measurements were executed at multiple streamwise and wall-normal wise locations downstream of the cylindrical element. The streamwise fluctuating signals were decomposed into large-, small-, and dissipative-scale signatures by corresponding cutoff filters. The scale interaction under the cylindrical perturbation was elaborated by comparing the small- and dissipative-scale amplitude/frequency modulation effects downstream of the cylinder element with the results observed in the unperturbed case. It was obtained that the large-scale fluctuations perform a stronger amplitude modulation on both the small and dissipative scales in the near-wall region. At the wall-normal positions of the cylinder height, the small-scale amplitude modulation coefficients are redistributed by the cylinder wake. The similar observation was noted in small-scale frequency modulation; however, the dissipative-scale frequency modulation seems to be independent of the cylindrical perturbation. The phase-relationship observation indicated that the cylindrical perturbation shortens the time shifts between both the small- and dissipative-scale variations (amplitude and frequency) and large-scale fluctuations. Then, the integral time scale dependence of the phase-relationship between the small/dissipative scales and large scales was also discussed. Furthermore, the discrepancy of small- and dissipative-scale time shifts relative to the large-scale motions was examined, which indicates that the small-scale amplitude/frequency leads the dissipative scales.

Bursting process of large- and small-scale structures in turbulent boundary layer perturbed by a cylinder roughness element

NASA Astrophysics Data System (ADS)

Tang, Zhanqi; Jiang, Nan; Zheng, Xiaobo; Wu, Yanhua

2016-05-01

Hot-wire measurements on a turbulent boundary layer flow perturbed by a wall-mounted cylinder roughness element (CRE) are carried out in this study. The cylindrical element protrudes into the logarithmic layer, which is similar to those employed in turbulent boundary layers by Ryan et al. (AIAA J 49:2210-2220, 2011. doi: 10.2514/1.j051012) and Zheng and Longmire (J Fluid Mech 748:368-398, 2014. doi: 10.1017/jfm.2014.185) and in turbulent channel flow by Pathikonda and Christensen (AIAA J 53:1-10, 2014. doi: 10.2514/1.j053407). The similar effects on both the mean velocity and Reynolds stress are observed downstream of the CRE perturbation. The series of hot-wire data are decomposed into large- and small-scale fluctuations, and the characteristics of large- and small-scale bursting process are observed, by comparing the bursting duration, period and frequency between CRE-perturbed case and unperturbed case. It is indicated that the CRE perturbation performs the significant impact on the large- and small-scale structures, but within the different impact scenario. Moreover, the large-scale bursting process imposes a modulation on the bursting events of small-scale fluctuations and the overall trend of modulation is not essentially sensitive to the present CRE perturbation, even the modulation extent is modified. The conditionally averaging fluctuations are also plotted, which further confirms the robustness of the bursting modulation in the present experiments.

Fracture-permeability behavior of shale

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

Carey, J. William; Lei, Zhou; Rougier, Esteban

The fracture-permeability behavior of Utica shale, an important play for shale gas and oil, was investigated using a triaxial coreflood device and X-ray tomography in combination with finite-discrete element modeling (FDEM). Fractures generated in both compression and in a direct-shear configuration allowed permeability to be measured across the faces of cylindrical core. Shale with bedding planes perpendicular to direct-shear loading developed complex fracture networks and peak permeability of 30 mD that fell to 5 mD under hydrostatic conditions. Shale with bedding planes parallel to shear loading developed simple fractures with peak permeability as high as 900 mD. In addition tomore » the large anisotropy in fracture permeability, the amount of deformation required to initiate fractures was greater for perpendicular layering (about 1% versus 0.4%), and in both cases activation of existing fractures are more likely sources of permeability in shale gas plays or damaged caprock in CO₂ sequestration because of the significant deformation required to form new fracture networks. FDEM numerical simulations were able to replicate the main features of the fracturing processes while showing the importance of fluid penetration into fractures as well as layering in determining fracture patterns.« less

Fracture-permeability behavior of shale

DOE PAGES

Carey, J. William; Lei, Zhou; Rougier, Esteban; ...

2015-05-08

The fracture-permeability behavior of Utica shale, an important play for shale gas and oil, was investigated using a triaxial coreflood device and X-ray tomography in combination with finite-discrete element modeling (FDEM). Fractures generated in both compression and in a direct-shear configuration allowed permeability to be measured across the faces of cylindrical core. Shale with bedding planes perpendicular to direct-shear loading developed complex fracture networks and peak permeability of 30 mD that fell to 5 mD under hydrostatic conditions. Shale with bedding planes parallel to shear loading developed simple fractures with peak permeability as high as 900 mD. In addition tomore » the large anisotropy in fracture permeability, the amount of deformation required to initiate fractures was greater for perpendicular layering (about 1% versus 0.4%), and in both cases activation of existing fractures are more likely sources of permeability in shale gas plays or damaged caprock in CO₂ sequestration because of the significant deformation required to form new fracture networks. FDEM numerical simulations were able to replicate the main features of the fracturing processes while showing the importance of fluid penetration into fractures as well as layering in determining fracture patterns.« less

Electrochemical cell having cylindrical electrode elements

DOEpatents

Nelson, Paul A.; Shimotake, Hiroshi

1982-01-01

A secondary, high temperature electrochemical cell especially adapted for lithium alloy negative electrodes, transition metal chalcogenide positive electrodes and alkali metal halide or alkaline earth metal halide electrolyte is disclosed. The cell is held within an elongated cylindrical container in which one of the active materials is filled around the outside surfaces of a plurality of perforate tubular current collectors along the length of the container. Each of the current collector tubes contain a concentric tubular layer of electrically insulative ceramic as an interelectrode separator. The active material of opposite polarity in elongated pin shape is positioned longitudinally within the separator layer. A second electrically conductive tube with perforate walls can be swagged or otherwise bonded to the outer surface of the pin as a current collector and the electrically insulative ceramic layer can be coated or otherwise layered onto the outer surface of this second current collector. Alternatively, the central pin electrode can include an axial core as a current collector.

Hybrid Seminumerical Simulation Scheme to Predict Transducer Outputs of Acoustic Microscopes.

PubMed

Nierla, Michael; Rupitsch, Stefan J

2016-02-01

We present a seminumerical simulation method called SIRFEM, which enables the efficient prediction of high-frequency transducer outputs. In particular, this is important for acoustic microscopy where the specimen under investigation is immersed in a coupling fluid. Conventional finite-element (FE) simulations for such applications would consume too much computational power due to the required spatial and temporal discretization, especially for the coupling fluid between ultrasonic transducer and specimen. However, FE simulations are in most cases essential to consider the mode conversion at and inside the solid specimen as well as the wave propagation in its interior. SIRFEM reduces the computational effort of pure FE simulations by treating only the solid specimen and a small part of the fluid layer with FE. The propagation in the coupling fluid from transducer to specimen and back is processed by the so-called spatial impulse response (SIR). Through this hybrid approach, the number of elements as well as the number of time steps for the FE simulation can be reduced significantly, as it is presented for an axis-symmetric setup. Three B-mode images of a plane 2-D setup-computed at a transducer center frequency of 20 MHz-show that SIRFEM is, furthermore, able to predict reflections at inner structures as well as multiple reflections between those structures and the specimen's surface. For the purpose of a pure 2-D setup, the SIR of a curved-line transducer is derived and compared to the response function of a cylindrically focused aperture of negligible extend in the third spatial dimension.

A bio-inspired microstructure induced by slow injection moulding of cylindrical block copolymers.

PubMed

Stasiak, Joanna; Brubert, Jacob; Serrani, Marta; Nair, Sukumaran; de Gaetano, Francesco; Costantino, Maria Laura; Moggridge, Geoff D

2014-08-28

It is well known that block copolymers with cylindrical morphology show alignment with shear, resulting in anisotropic mechanical properties. Here we show that well-ordered bi-directional orientation can be achieved in such materials by slow injection moulding. This results in a microstructure, and anisotropic mechanical properties, similar to many natural tissues, making this method attractive for engineering prosthetic fibrous tissues. An application of particular interest to us is prosthetic polymeric heart valve leaflets, mimicking the shape, microstructure and hence performance of the native valve. Anisotropic layers have been observed for cylinder-forming block copolymers centrally injected into thin circular discs. The skin layers exhibit orientation parallel to the flow direction, whilst the core layer shows perpendicularly oriented domains; the balance of skin to core layers can be controlled by processing parameters such as temperature and injection rate. Heart valve leaflets with a similar layered structure have been prepared by injection moulding. Numerical modelling demonstrates that such complex orientation can be explained and predicted by the balance of shear and extensional flow.

Free vibrations of a multilayered non-circular cylindrical shell

NASA Astrophysics Data System (ADS)

Zelinskaya, Anna V.

2018-05-01

Free vibrations of an elastic non-circular cylindrical shell of intermediate length are considered. The shell is assumed heterogeneous in the thickness direction, in its part it may be multilayered. In order to derive the equations of stability, we use the Timoshenko-Reissner model. According to it, a shell that is heterogeneous can be replaced by a homogeneous shell with the equivalent bending and transversal shear stiffness. We obtain the approximate asymptotic formula for a frequency that takes into account an influence of a transversal shear and a variability of a directrix curvature. As an example, a three-layer elliptical shell with hinged edges and a soft middle layer is analyzed.

Nanopatterned articles produced using surface-reconstructed block copolymer films

DOEpatents

Russell, Thomas P.; Park, Soojin; Wang, Jia-Yu; Kim, Bokyung

2016-06-07

Nanopatterned surfaces are prepared by a method that includes forming a block copolymer film on a substrate, annealing and surface reconstructing the block copolymer film to create an array of cylindrical voids, depositing a metal on the surface-reconstructed block copolymer film, and heating the metal-coated block copolymer film to redistribute at least some of the metal into the cylindrical voids. When very thin metal layers and low heating temperatures are used, metal nanodots can be formed. When thicker metal layers and higher heating temperatures are used, the resulting metal structure includes nanoring-shaped voids. The nanopatterned surfaces can be transferred to the underlying substrates via etching, or used to prepare nanodot- or nanoring-decorated substrate surfaces.

Deposition, Heat Treatment And Characterization of Two Layer Bioactive Coatings on Cylindrical PEEK

PubMed Central

Durham, John W.; Rabiei, Afsaneh

2015-01-01

Polyether ether ketone (PEEK) rods were coated via ion beam asssited deposition (IBAD) at room temperature. The coating consists of a two-layer design of yttria-stabilized zirconia (YSZ) as a heat-protection layer, and hydroxyapatite (HA) as a top layer to increase bioactivity. A rotating substrate holder was designed to deposit an even coating on the cylindrical surface of PEEK rods; the uniformity is verified by cross-sectional measurements using scanning electron microscopy (SEM). Deposition is followed by heat treatment of the coating using microwave annealing and autoclaving. Transmission electron microscopy (TEM) showed a dense, uniform columnar grain structure in the YSZ layer that is well bonded to the PEEK substrate, while the calcium phosphate layer was amorphous and pore-free in its as-deposited state. Subsequent heat treatment via microwave energy introduced HA crystallization in the calcium phosphate layer and additional autoclaving further expanded the crystallization of the HA layer. Chemical composition evaluation of the coating indicated the Ca/P ratios of the HA layer to be near that of stoichiometric HA, with minor variations through the HA layer thickness. The adhesion strength of as-deposited HA/YSZ coatings on smooth, polished PEEK surfaces was mostly unaffected by microwave heat treatment, but decreased with additional autoclave treatment. Increasing surface roughness showed improvement of bond strength. PMID:27713592

Multiple-Cone Sunshade for a Spaceborne Telescope

NASA Technical Reports Server (NTRS)

Cafferty, Terry; Ford, Virginia

2008-01-01

A document describes a sunshade assembly for the spaceborne telescope of the Terrestrial Planet Finder Coronagraph mission. During operation, the telescope is aimed at target stars in the semihemisphere away from the Earth's Sun. The observatory rotates about its pointing axis during a single star observation, resulting in relative movement of the Sun. The sunshade assembly protects the telescope against excessive solar-induced thermal distortions for times long enough to complete observations. The assembly includes a cylindrical baffle immediately surrounding the telescope, and a series of coaxial conical shields at half-cone angle increments of between 3 and 6. The black inner surface of the cylindrical baffle suppresses stray light. The outer surface of the cylindrical baffle and all the surfaces of the conical shields except the outermost one are specular and highly reflective in the infrared. The outer surface of the outer shield is a material with low solar absorptance and high infrared emittance, such as silverized Teflon or white paint. This arrangement strongly radiatively couples each shield layer more effectively to cold space than to adjacent shield layers. The result is that the solar-driven temperature gradients in the cylindrical baffle are nearly negated, and only weakly communicated to the highly-infrared-reflective face of the primary telescope mirror.

Steady groundwater flow through many cylindrical inhomogeneities in a multi-aquifer system

NASA Astrophysics Data System (ADS)

Bakker, Mark

2003-06-01

A new approach is presented for the simulation of steady-state groundwater flow in multi-aquifer systems that contain many cylindrical inhomogeneities. The hydraulic conductivity of all aquifers and the resistance of all leaky layers may be different inside each cylinder. The approach is based on separation of variables and combines principles of the theory for multi-aquifer flow with principles of the analytic element method. The solution fulfills the governing differential equations exactly everywhere; the head, flow, and leakage between aquifers may be computed analytically at any point in the aquifer system. The boundary conditions along the circumference of the cylinder are satisfied approximately, but may be met at any precision. Two examples are discussed to illustrate the accuracy of the approach and the significance of inhomogeneities in multi-aquifer systems. The first application simulates the vertical and horizontal, advective spreading of a conservative tracer in a homogeneous aquifer that is overlain by an aquifer with cylindrical inclusions of higher permeability. The second application concerns the three-dimensional shape of the capture zone of a well that is screened in the bottom aquifer of a three-aquifer system. The capture zone extends to the top aquifer due to cylindrical holes of lower resistance in the separating clay layers.

Influence of hole shape on sound absorption of underwater anechoic layers

NASA Astrophysics Data System (ADS)

Ye, Changzheng; Liu, Xuewei; Xin, Fengxian; Lu, Tian Jian

2018-07-01

A theoretical model is established to evaluate the sound absorption performance of underwater anechoic layers containing periodically distributed axial holes. Based on the concept for homogenized equivalent layer and on the theory of wave propagation in viscoelastic cylindrical tubes, the transfer function method is used to obtain the absorption coefficient of the anechoic layer adhered on the rigid plate. Three different types of axial holes are considered, the cylindrical, the conical and the horn shaped one. Results obtained with full finite element simulations are used to validate the model predictions. For each hole type, the vibration characteristics of the anechoic layer as well as the propagation of longitudinal and transverse waves in the layer are analyzed in detail to explore the physical mechanisms underlying its absorption performance. Furthermore, a three-dimensional finite element model for oblique incidence is developed to study the effect of hole shape at different incidence angles. The results show that two new absorption peaks appear since the oblique incidence excites two horizontal modes. Among the three hole types, the horn one achieves the best absorption performance at relatively low frequencies both in normal incidence and in oblique incidence.

Heat pipes for use in a magnetic field

DOEpatents

Werner, R.W.; Hoffman, M.A.

1983-07-19

A heat pipe configuration for use in a magnetic field environment of a fusion reactor is disclosed. Heat pipes for operation in a magnetic field when liquid metal working fluids are used are optimized by flattening of the heat pipes having an unobstructed annulus which significantly reduces the adverse side region effect of the prior known cylindrically configured heat pipes. The flattened heat pipes operating in a magnetic field can remove 2--3 times the heat as a cylindrical heat pipe of the same cross sectional area. 4 figs.

Impact of the lithographic discontinuities on the karst conduit development - insights from modelling

NASA Astrophysics Data System (ADS)

Petrus, Karine; Szymczak, Piotr

2016-04-01

Karst formation is controlled by the processes of the fluid flow and reactant transport coupled to the chemical erosion of the limestone rock [1]. The coupling between these processes can lead to a number of different instabilities, resulting in the formation of dissolutional voids, caverns and conduits. Arguably the simplest systems of this kind are solution pipes, in which gravitationally driven water movement carves vertical conduits in limestone rocks. In the homogeneous rocks these conduits are often cylindrical, with almost a constant diameter along their length. However, in a stratified medium, the morphology of the pipes changes. For example, if a number of less porous layers is introduced in an otherwise homogeneous medium, then the pipes are observed to narrow as they cross the layers and then widen up to form bulbous caverns as they emerge from the layer [1]. In this communication, we investigate these effects more closely, considering different kind of lithographic discontinuities to be present in the system: the layers of increased/decreased porosity and/or permeability as well as the solubility which is different from the rest of the system. Using a Darcy-scale numerical model we analyze the effects these layers have on the shape and growth of solution pipes and compare the results on the piping morphologies observed in nature. Finally we comment on the possible relevance of these results to the cave-formation phenomena and the inception horizon concept [3]. References: 1.Howard A. D., The development of karst features, Bull. Natl. Spel. Soc. 25, 45-65 (1963) 2. Petrus, K. and Szymczak, P., Influence of layering on the formation and growth of solution pipes. Frontiers in Physics (submitted) 3.Filipponi , M., Jeannin, P. and Tacher, L., Evidence of inception horizons in karst conduit networks, Geomorphology, 106, 86-99 (2009)

An analytical poroelastic model for ultrasound elastography imaging of tumors

NASA Astrophysics Data System (ADS)

Tauhidul Islam, Md; Chaudhry, Anuj; Unnikrishnan, Ginu; Reddy, J. N.; Righetti, Raffaella

2018-01-01

The mechanical behavior of biological tissues has been studied using a number of mechanical models. Due to the relatively high fluid content and mobility, many biological tissues have been modeled as poroelastic materials. Diseases such as cancers are known to alter the poroelastic response of a tissue. Tissue poroelastic properties such as compressibility, interstitial permeability and fluid pressure also play a key role for the assessment of cancer treatments and for improved therapies. At the present time, however, a limited number of poroelastic models for soft tissues are retrievable in the literature, and the ones available are not directly applicable to tumors as they typically refer to uniform tissues. In this paper, we report the analytical poroelastic model for a non-uniform tissue under stress relaxation. Displacement, strain and fluid pressure fields in a cylindrical poroelastic sample containing a cylindrical inclusion during stress relaxation are computed. Finite element simulations are then used to validate the proposed theoretical model. Statistical analysis demonstrates that the proposed analytical model matches the finite element results with less than 0.5% error. The availability of the analytical model and solutions presented in this paper may be useful to estimate diagnostically relevant poroelastic parameters such as interstitial permeability and fluid pressure, and, in general, for a better interpretation of clinically-relevant ultrasound elastography results.

In-house manufacturing of cylindrical silicone models for hemodynamic research

NASA Astrophysics Data System (ADS)

Denisenko, Nikita S.; Kulik, Viktor M.

2017-10-01

Laboratory studies of fluid motion in artificial vessels modeling a distinct part of circulatory system of human are of a great importance for fundamental biomechanics and for medical applications. In the medicine they are used for advancing known and developing new methods for curing cardiovascular diseases. In biomechanics, the phantoms of blood vessels are used for studying the fluid motion. However, they are quite expensive. Therefore, a development of technique for in-house manufacturing of phantoms is quite attractive. In this paper methods of manufacturing cylindrical channels of silicone rubbers (the model of the straight part of an artery) and determination of their elastic properties are described. A specially developed acrylic mold is used for this purpose. The phantoms are cast from a mixture of SKTN-A silicone and PMS-5 oil (Penta-91, Novosibirsk, Russia). The oil is used for changing elasticity properties of the silicone.

Cylindrically symmetric cosmological model of the universe in modified gravity

NASA Astrophysics Data System (ADS)

Mishra, B.; Vadrevu, Samhita

2017-02-01

In this paper, we have constructed the cosmological models of the universe in a cylindrically symmetric space time in two classes of f(R,T) gravity (Harko et al. in Phys. Rev. D 84:024020, 2011). We have discussed two cases: one in the linear form and the other in the quadratic form of R. The matter is considered to be in the form of perfect fluid. It is observed that in the first case, the pressure and energy density remain the same, which reduces to a Zeldovich fluid. In the second case we have studied the quadratic function of f(R,T) gravity in the form f(R)=λ(R+R2) and f(T)=λ T. In the second case the pressure is in the negative domain and the energy density is in the positive domain, which confirms that the equation of state parameter is negative. The physical properties of the constructed models are studied.

Designing cylindrical implosion experiments on NIF to study deceleration phase of Rayleigh-Taylor

NASA Astrophysics Data System (ADS)

Vazirani, N.; Kline, J. L.; Loomis, E.; Sauppe, J. P.; Palaniyappan, S.; Flippo, K.; Srinivasan, B.; Malka, E.; Bose, A.; Shvarts, D.

2017-10-01

The Rayleigh-Taylor (RT) hydrodynamic instability occurs when a lower density fluid pushes on a higher density fluid. This occurs in inertial confinement fusion (ICF) implosions at each of the capsule interfaces during the initial acceleration and the deceleration as it stagnates. The RT instabilities mix capsule material into the fusion fuel degrading the Deuterium-Tritium reactivity and ultimately play a key role in limiting target performance. While significant effort has focused on understanding RT at the outer capsule surface, little work has gone into understanding the inner surface RT instability growth during the deceleration phase. Direct measurements of the RT instability are difficult to make at high convergence in a spherical implosion. Here we present the design of a cylindrical implosion system for the National Ignition Facility for studying deceleration phase RT. We will discuss the experimental design, the estimated instability growth, and our outstanding concerns.

Multiple discharge cylindrical pump collector

DOEpatents

Dunn, Charlton; Bremner, Robert J.; Meng, Sen Y.

1989-01-01

A space-saving discharge collector 40 for the rotary pump 28 of a pool-type nuclear reactor 10. An annular collector 50 is located radially outboard for an impeller 44. The annular collector 50 as a closed outer periphery 52 for collecting the fluid from the impeller 44 and producing a uniform circumferential flow of the fluid. Turning means comprising a plurality of individual passageways 54 are located in an axial position relative to the annular collector 50 for receiving the fluid from the annular collector 50 and turning it into a substantially axial direction.

Blunt Body Near-Wake Flow Field at Mach 10

NASA Technical Reports Server (NTRS)

Horvath, Thomas; Hannemann, Klaus

1997-01-01

Tests were conducted in a Mach 10 air flow to examine the reattachment process of a free shear layer associated with the near wake of a 70 deg half angle, spherically blunted cone having a cylindrical after body. The nominal free-stream Reynolds number based on model diameter ranged from 0.25 x l0(exp 6) to 1 x l0(exp 6) and the angle of incidence set at 0 and +/- 20 deg. The present study was designed to complement previously reported Mach 6 perfect air tests as well as results obtained in several hypervelocity facilities capable of producing real gas effects. Surface heating rates were inferred from temperature time histories from coaxial surface thermocouples on the model forebody and thin film resistance gages along the model base and cylindrical after body. Limited forebody, base, and support sting surface pressures were obtained with piezoresistive Experimental results are compared to laminar perfect gas predictions provided by a 3-0 Navier Stokes code (NSHYP). Shear layer impingement on the instrumented cylindrical after body resulted in a localized heating maximum that was 16 to 18percent of the forebody stagnation point and a factor of 2 higher than laminar predictions, suggesting a transitional or turbulent shear layer. transducers.

Current switching ratio optimization using dual pocket doping engineering

NASA Astrophysics Data System (ADS)

Dash, Sidhartha; Sahoo, Girija Shankar; Mishra, Guru Prasad

2018-01-01

This paper presents a smart idea to maximize current switching ratio of cylindrical gate tunnel FET (CGT) by growing pocket layers in both source and channel region. The pocket layers positioned in the source and channel of the device provides significant improvement in ON-state and OFF-state current respectively. The dual pocket doped cylindrical gate TFET (DP-CGT) exhibits much superior performance in term of drain current, transconductance and current ratio as compared to conventional CGT, channel pocket doped CGT (CP-CGT) and source pocket doped CGT (SP-CGT). Further, the current ratio has been optimized w.r.t. width and instantaneous position both the pocket layers. The much improved current ratio and low power consumption makes the proposed device suitable for low-power and high speed application. The simulation work of DP-CGT is done using 3D Sentaurus TCAD device simulator from Synopsys.

Cylindrical and spherical Akhmediev breather and freak waves in ultracold neutral plasmas

NASA Astrophysics Data System (ADS)

El-Tantawy, S. A.; El-Awady, E. I.

2018-01-01

The properties of cylindrical and spherical ion-acoustic breathers Akhmediev breather and freak waves in strongly coupled ultracold neutral plasmas (UNPs), whose constituents are inertial strongly coupled ions and weakly coupled Maxwellian electrons, are investigated numerically. Using the derivative expansion method, the basic set of fluid equations is reduced to a nonplanar (cylindrical and spherical)/modified nonlinear Schrödinger equation (mNLSE). The analytical solutions of the mNLSE were not possible until now, so their numerical solutions are obtained using the finite difference scheme with the help of the Dirichlet boundary conditions. Moreover, the criteria for the existence and propagation of breathers are discussed in detail. The geometrical effects due to the cylindrical and spherical geometries on the breather profile are studied numerically. It is found that the propagation of the ion-acoustic breathers in one-dimensional planar and nonplanar geometries is very different. Finally, our results may help to manipulate matter breathers experimentally in UNPs.

Microfluidic step-emulsification in a cylindrical geometry

NASA Astrophysics Data System (ADS)

Chakraborty, Indrajit; Leshansky, Alexander M.

2016-11-01

The model microfluidic device for high-throughput droplet generation in a confined cylindrical geometry is investigated numerically. The device comprises of core-annular pressure-driven flow of two immiscible viscous liquids through a cylindrical capillary connected co-axially to a tube of a larger diameter through a sudden expansion, mimicking the microfluidic step-emulsifier (1). To study this problem, the numerical simulations of axisymmetric Navier-Stokes equations have been carried out using an interface capturing procedure based on coupled level set and volume-of-fluid (CLSVOF) methods. The accuracy of the numerical method was favorably tested vs. the predictions of the linear stability analysis of core-annular two-phase flow in a cylindrical capillary. Three distinct flow regimes can be identified: the dripping (D) instability near the entrance to the capillary, the step- (S) and the balloon- (B) emulsification at the step-like expansion. Based on the simulation results we present the phase diagram quantifying transitions between various regimes in plane of the capillary number and the flow-rate ratio. MICROFLUSA EU H2020 project.

Research on soundproof properties of cylindrical shells of generalized phononic crystals

NASA Astrophysics Data System (ADS)

Liu, Ru; Shu, Haisheng; Wang, Xingguo

2017-04-01

Based on the previous studies, the concept of generalized phononic crystals (GPCs) is further introduced into the cylindrical shell structures in this paper. And a type of cylindrical shells of generalized phononic crystals (CS-GPCs) is constructed, the structural field and acoustic-structural coupled field of the composite cylindrical shells are examined respectively. For the structural field, the transfer matrix method of mechanical state vector is adopted to build the transfer matrix of radial waves propagating from inside to outside. For the acoustic-structural coupled field, the expressions of the acoustic transmission/reflection coefficients and the sound insulation of acoustic waves with the excitation of center line sound source are set up. And the acoustic transmission coefficient and the frequency response of sound insulation in this mode were numerical calculated. Furthermore, the theoretical analysis results are verified by using the method of combining the numerical calculation and finite element simulation. Finally, the effects of inner and outer fluid parameters on the transmission/reflection coefficients of CS-GPCs are analyzed in detail.

Fully-Coupled Fluid/Structure Vibration Analysis Using MSC/NASTRAN

NASA Technical Reports Server (NTRS)

Fernholz, Christian M.; Robinson, Jay H.

1996-01-01

MSC/NASTRAN's performance in the solution of fully-coupled fluid/structure problems is evaluated. NASTRAN is used to perform normal modes (SOL 103) and forced-response analyses (SOL 108, 111) on cylindrical and cubic fluid/structure models. Bulk data file cards unique to the specification of a fluid element are discussed and analytic partially-coupled solutions are derived for each type of problem. These solutions are used to evaluate NASTRAN's solutions for accuracy. Appendices to this work include NASTRAN data presented in fringe plot form, FORTRAN source code listings written in support of this work, and NASTRAN data file usage requirements for each analysis.

Computer code for gas-liquid two-phase vortex motions: GLVM

NASA Technical Reports Server (NTRS)

Yeh, T. T.

1986-01-01

A computer program aimed at the phase separation between gas and liquid at zero gravity, induced by vortex motion, is developed. It utilizes an explicit solution method for a set of equations describing rotating gas-liquid flows. The vortex motion is established by a tangential fluid injection. A Lax-Wendroff two-step (McCormack's) numerical scheme is used. The program can be used to study the fluid dynamical behavior of the rotational two-phase fluids in a cylindrical tank. It provides a quick/easy sensitivity test on various parameters and thus provides the guidance for the design and use of actual physical systems for handling two-phase fluids.

Uniform bulk material processing using multimode microwave radiation

DOEpatents

Varma, Ravi; Vaughn, Worth E.

2000-01-01

An apparatus for generating uniform heating in material contained in a cylindrical vessel is described. TE.sub.10 -mode microwave radiation is coupled into a cylindrical microwave transition such that microwave radiation having TE.sub.11 -, TE.sub.01 - and TM.sub.01 -cylindrical modes is excited therein. By adjusting the intensities of these modes, substantially uniform heating of materials contained in a cylindrical drum which is coupled to the microwave transition through a rotatable choke can be achieved. The use of a poor microwave absorbing insulating cylindrical insert, such as aluminum oxide, for separating the material in the container from the container walls and for providing a volume through which air is circulated is expected to maintain the container walls at room temperature. The use of layer of highly microwave absorbing material, such as SiC, inside of the insulating insert and facing the material to be heated is calculated to improve the heating pattern of the present apparatus.

Systems, compositions, and methods for fluid purification

DOEpatents

Ho, W.S. Winston; Verweij, Hendrik; Shqau, Krenar; Ramasubranian, Kartik

2015-12-22

Disclosed herein are membranes comprising a substrate, a support layer, and a selective layer. In some embodiments the membrane may further comprise a permeable layer. Methods of forming membranes are also disclosed comprising forming a support layer on a substrate, removing adsorbed species from the support layer, preparing a solution containing inorganic materials of a selective layer, contacting the support layer with the solution, drying the membrane, and exposing the membrane to rapid thermal processing. Also disclosed are methods of fluid purification comprising providing a membrane having a feed side and a permeable side, passing a fluid mixture across the feed side of the membrane, providing a driving force for transmembrane permeation, removing from the permeate side a permeate stream enriched in a purified fluid, and withdrawing from the feed side a fluid that is depleted in a purified fluid.

Full-vectorial finite element method in a cylindrical coordinate system for loss analysis of photonic wire bends

NASA Astrophysics Data System (ADS)

Kakihara, Kuniaki; Kono, Naoya; Saitoh, Kunimasa; Koshiba, Masanori

2006-11-01

This paper presents a new full-vectorial finite-element method in a local cylindrical coordinate system, to effectively analyze bending losses in photonic wires. The discretization is performed in the cross section of a three-dimensional curved waveguide, using hybrid edge/nodal elements. The solution region is truncated by anisotropic, perfectly matched layers in the cylindrical coordinate system, to deal properly with leaky modes of the waveguide. This approach is used to evaluate bending losses in silicon wire waveguides. The numerical results of the present approach are compared with results calculated with an equivalent straight waveguide approach and with reported experimental data. These comparisons together demonstrate the validity of the present approach based on the cylindrical coordinate system and also clarifies the limited validity of the equivalent straight waveguide approximation.

Atomistic Modeling of the Fluid-Solid Interface in Simple Fluids

NASA Astrophysics Data System (ADS)

Hadjiconstantinou, Nicolas; Wang, Gerald

2017-11-01

Fluids can exhibit pronounced structuring effects near a solid boundary, typically manifested in a layered structure that has been extensively shown to directly affect transport across the interface. We present and discuss several results from molecular-mechanical modeling and molecular-dynamics (MD) simulations aimed at characterizing the structure of the first fluid layer directly adjacent to the solid. We identify a new dimensionless group - termed the Wall number - which characterizes the degree of fluid layering, by comparing the competing effects of wall-fluid interaction and thermal energy. We find that in the layering regime, several key features of the first layer layer - including its distance from the solid, its width, and its areal density - can be described using mean-field-energy arguments, as well as asymptotic analysis of the Nernst-Planck equation. For dense fluids, the areal density and the width of the first layer can be related to the bulk fluid density using a simple scaling relation. MD simulations show that these results are broadly applicable and robust to the presence of a second confining solid boundary, different choices of wall structure and thermalization, strengths of fluid-solid interaction, and wall geometries.

Fluid flows created by swimming bacteria drive self-organization in confined suspensions

PubMed Central

Lushi, Enkeleida; Wioland, Hugo; Goldstein, Raymond E.

2014-01-01

Concentrated suspensions of swimming microorganisms and other forms of active matter are known to display complex, self-organized spatiotemporal patterns on scales that are large compared with those of the individual motile units. Despite intensive experimental and theoretical study, it has remained unclear the extent to which the hydrodynamic flows generated by swimming cells, rather than purely steric interactions between them, drive the self-organization. Here we use the recent discovery of a spiral-vortex state in confined suspensions of Bacillus subtilis to study this issue in detail. Those experiments showed that if the radius of confinement in a thin cylindrical chamber is below a critical value, the suspension will spontaneously form a steady single-vortex state encircled by a counter-rotating cell boundary layer, with spiral cell orientation within the vortex. Left unclear, however, was the flagellar orientation, and hence the cell swimming direction, within the spiral vortex. Here, using a fast simulation method that captures oriented cell–cell and cell–fluid interactions in a minimal model of discrete particle systems, we predict the striking, counterintuitive result that in the presence of collectively generated fluid motion, the cells within the spiral vortex actually swim upstream against those flows. This prediction is then confirmed by the experiments reported here, which include measurements of flagella bundle orientation and cell tracking in the self-organized state. These results highlight the complex interplay between cell orientation and hydrodynamic flows in concentrated suspensions of microorganisms. PMID:24958878

Blunt body near wake flow field at Mach 6

NASA Technical Reports Server (NTRS)

Horvath, Thomas J.; McGinley, Catherine B.; Hannemann, Klaus

1996-01-01

Tests were conducted in a Mach 6 flow to examine the reattachment process of an axisymmetric free shear layer associated with the near wake of a 70 deg. half angle, spherically blunted cone with a cylindrical after body. Model angle of incidence was fixed at 0 deg. and free-stream Reynolds numbers based on body diameter ranged from 0.5 x 10(exp 6) to 4 x 10(exp 6). The sensitivity of wake shear layer transition on reattachment heating was investigated. The present perfect gas study was designed to compliment results obtained previously in facilities capable of producing real gas effects. The instrumented blunted cone model was designed primarily for testing in high enthalpy hypervelocity shock tunnels in both this country and abroad but was amenable for testing in conventional hypersonic blowdown wind tunnels as well. Surface heating rates were inferred from temperature - time histories from coaxial surface thermocouples on the model forebody and thin film resistance gages along the model base and cylindrical after body. General flow feature (bow shock, wake shear layer, and recompression shock) locations were visually identified by schlieren photography. Mean shear layer position and growth were determined from intrusive pitot pressure surveys. In addition, wake surveys with a constant temperature hot-wire anemometer were utilized to qualitatively characterize the state of the shear layer prior to reattachment. Experimental results were compared to laminar perfect gas predictions provided by a 3-D Navier Stokes code (NSHYP). Shear layer impingement on the instrumented cylindrical after body resulted in a localized heating maximum that was 21 to 29 percent of the forebody stagnation point heating. Peak heating resulting from the reattaching shear layer was found to be a factor of 2 higher than laminar predictions, which suggested a transitional shear layer. Schlieren flow visualization and fluctuating voltage time histories and spectra from the hot wire surveys across the shear layer substantiate this observation. The sensitivity of surface heating to forebody roughness was characterized for a reattaching shear layer. For example, at R(sub infinity), d = 4 x 10(exp 6), when the shear layer was transitional, the magnitude of peak heating from shear layer impingement was reduced by approximately 24 percent when transition grit was applied to the forebody. The spatial location of the local peak, however, remained unchanged.

Dispersion, Mixing, and Combustion in Uniform- and Variable-Density Air-Breathing High-Speed Propulsion Flows

DTIC Science & Technology

2013-08-28

and dispersion whose behavior is relevant to fuel-injection in propulsion devices. The latter investigations were conducted in water that allows...initially sharp scalar gradients in this high Schmidt-number fluid medium ( water : ⁄ ). Generally, such scalar plumes re reported to exhibit... Flowmetering : The Characteristics of Cylindrical Nozzles with Sharp Upstream Edges. Int. J. Heat and Fluid Flow 1(3):123-132. 3. Research personnel

Investigation of phase diagrams for cylindrical Ising nanotube using cellular automata

NASA Astrophysics Data System (ADS)

Astaraki, M.; Ghaemi, M.; Afzali, K.

2018-05-01

Recent developments in the field of applied nanoscience and nanotechnology have heightened the need for categorizing various characteristics of nanostructures. In this regard, this paper establishes a novel method to investigate magnetic properties (phase diagram and spontaneous magnetization) of a cylindrical Ising nanotube. Using a two-layer Ising model and the core-shell concept, the interactions within nanotube has been modelled. In the model, both ferromagnetic and antiferromagnetic cases have been considered. Furthermore, the effect of nanotube's length on the critical temperature is investigated. The model has been simulated using cellular automata approach and phase diagrams were constructed for different values of inter- and intra-layer couplings. For the antiferromagnetic case, the possibility of existence of compensation point is observed.

Nanopatterned articles produced using reconstructed block copolymer films

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

Russell, Thomas P.; Park, Soojin; Wang;, Jia-Yu

Nanopatterned surfaces are prepared by a method that includes forming a block copolymer film on a substrate, annealing and surface reconstructing the block copolymer film to create an array of cylindrical voids, depositing a metal on the surface-reconstructed block copolymer film, and heating the metal-coated block copolymer film to redistribute at least some of the metal into the cylindrical voids. When very thin metal layers and low heating temperatures are used, metal nanodots can be formed. When thicker metal layers and higher heating temperatures are used, the resulting metal structure includes nanoring-shaped voids. The nanopatterned surfaces can be transferred tomore » the underlying substrates via etching, or used to prepare nanodot- or nanoring-decorated substrate surfaces.« less

Method of producing nanopatterned articles using surface-reconstructed block copolymer films

DOEpatents

Russell, Thomas P; Park, Soojin; Wang, Jia-Yu; Kim, Bokyung

2013-08-27

Nanopatterned surfaces are prepared by a method that includes forming a block copolymer film on a substrate, annealing and surface reconstructing the block copolymer film to create an array of cylindrical voids, depositing a metal on the surface-reconstructed block copolymer film, and heating the metal-coated block copolymer film to redistribute at least some of the metal into the cylindrical voids. When very thin metal layers and low heating temperatures are used, metal nanodots can be formed. When thicker metal layers and higher heating temperatures are used, the resulting metal structure includes nanoring-shaped voids. The nanopatterned surfaces can be transferred to the underlying substrates via etching, or used to prepare nanodot- or nanoring-decorated substrate surfaces.

Convection in superposed fluid and porous layers

NASA Technical Reports Server (NTRS)

Chen, Falin; Chen, C. F.

1992-01-01

Thermal convection due to heating from below in a porous layer underlying a fluid layer has been analyzed using the Navier-Stokes equations for the fluid layers and the extended Darcy equation (including Brinkman and Forchheimer terms) for the porous layer. The flow is assumed to be two-dimensional and periodic in the horizontal direction. The numerical scheme used is a combined Galerkin and finite-difference method, and appropriate boundary conditions are applied at the interface. Results have been obtained for depth ratios of 0, 0.1, 0.2, 0.5, and 1.0, where this ratio is defined as the ratio of the thickness of the fluid layer to that of the porous layer. For the depth ratio of 0.1, the convection is dominated by the porous layer, similar to the situation at onset, even though the Rayleigh number for the fluid layer is well into the supercritical regime.

Pressurized Lunar Rover (PLR)

NASA Technical Reports Server (NTRS)

Creel, Kenneth; Frampton, Jeffrey; Honaker, David; Mcclure, Kerry; Zeinali, Mazyar; Bhardwaj, Manoj; Bulsara, Vatsal; Kokan, David; Shariff, Shaun; Svarverud, Eric

1992-01-01

The objective of this project was to design a manned pressurized lunar rover (PLR) for long-range transportation and for exploration of the lunar surface. The vehicle must be capable of operating on a 14-day mission, traveling within a radius of 500 km during a lunar day or within a 50-km radius during a lunar night. The vehicle must accommodate a nominal crew of four, support two 28-hour EVA's, and in case of emergency, support a crew of six when near the lunar base. A nominal speed of ten km/hr and capability of towing a trailer with a mass of two mt are required. Two preliminary designs have been developed by two independent student teams. The PLR 1 design proposes a seven meter long cylindrical main vehicle and a trailer which houses the power and heat rejection systems. The main vehicle carries the astronauts, life support systems, navigation and communication systems, lighting, robotic arms, tools, and equipment for exploratory experiments. The rover uses a simple mobility system with six wheels on the main vehicle and two on the trailer. The nonpressurized trailer contains a modular radioisotope thermoelectric generator (RTG) supplying 6.5 kW continuous power. A secondary energy storage for short-term peak power needs is provided by a bank of lithium-sulfur dioxide batteries. The life support system is partly a regenerative system with air and hygiene water being recycled. A layer of water inside the composite shell surrounds the command center allowing the center to be used as a safe haven during solar flares. The PLR 1 has a total mass of 6197 kg. It has a top speed of 18 km/hr and is capable of towing three metric tons, in addition to the RTG trailer. The PLR 2 configuration consists of two four-meter diameter, cylindrical hulls which are passively connected by a flexible passageway, resulting in the overall vehicle length of 11 m. The vehicle is driven by eight independently suspended wheels. The dual-cylinder concept allows articulated as well as double Ackermann steering. The primary power of 8 kW is supplied by a dynamic isotope system using a closed Brayton cycle with a xenon-hydrogen mixture as the working fluid. A sodium-sulfur battery serves as the secondary power source. Excess heat produced by the primary power system and other rover systems is rejected by radiators located on the top of the rear cylinder. The total mass of the PLR 2 is 7015 kg. Simplicity and low total weight have been the driving principles behind the design of PLR 1. The overall configuration consists of a 7-m-long, 3-m-diameter cylindrical main vehicle and a two-wheeled trailer. The cylinder of the main body is capped by eight-section, faceted, semi-hemispherical ends. The trailer contains the RTG power source and is not pressurized. The shell of the main body is constructed of a layered carbon fiber/foam/Kevlar sandwich structure. Included in the shell is a layer of water for radiation protection. The layer of water extends from the front of the rover over the crew compartment and creates a safe haven for the crew during a solar flare-up. The carbon fiber provides the majority of the strength and stiffness and the Kevlar provides protection from micrometeoroids. The Kevlar is covered with a gold foil and multi-layer insulation (MLI) to reduce radiation degradation and heat transfer through the wall. A thin thermoplastic layer seals the fiber and provides additional strength.

Pressurized Lunar Rover (PLR)

NASA Astrophysics Data System (ADS)

Creel, Kenneth; Frampton, Jeffrey; Honaker, David; McClure, Kerry; Zeinali, Mazyar; Bhardwaj, Manoj; Bulsara, Vatsal; Kokan, David; Shariff, Shaun; Svarverud, Eric

The objective of this project was to design a manned pressurized lunar rover (PLR) for long-range transportation and for exploration of the lunar surface. The vehicle must be capable of operating on a 14-day mission, traveling within a radius of 500 km during a lunar day or within a 50-km radius during a lunar night. The vehicle must accommodate a nominal crew of four, support two 28-hour EVA's, and in case of emergency, support a crew of six when near the lunar base. A nominal speed of ten km/hr and capability of towing a trailer with a mass of two mt are required. Two preliminary designs have been developed by two independent student teams. The PLR 1 design proposes a seven meter long cylindrical main vehicle and a trailer which houses the power and heat rejection systems. The main vehicle carries the astronauts, life support systems, navigation and communication systems, lighting, robotic arms, tools, and equipment for exploratory experiments. The rover uses a simple mobility system with six wheels on the main vehicle and two on the trailer. The nonpressurized trailer contains a modular radioisotope thermoelectric generator (RTG) supplying 6.5 kW continuous power. A secondary energy storage for short-term peak power needs is provided by a bank of lithium-sulfur dioxide batteries. The life support system is partly a regenerative system with air and hygiene water being recycled. A layer of water inside the composite shell surrounds the command center allowing the center to be used as a safe haven during solar flares. The PLR 1 has a total mass of 6197 kg. It has a top speed of 18 km/hr and is capable of towing three metric tons, in addition to the RTG trailer. The PLR 2 configuration consists of two four-meter diameter, cylindrical hulls which are passively connected by a flexible passageway, resulting in the overall vehicle length of 11 m. The vehicle is driven by eight independently suspended wheels. The dual-cylinder concept allows articulated as well as double Ackermann steering. The primary power of 8 kW is supplied by a dynamic isotope system using a closed Brayton cycle with a xenon-hydrogen mixture as the working fluid.

Analysis of the Damping Characteristics of Cylindrical Resonators Influenced by Piezoelectric Electrodes

PubMed Central

Sun, Jiangkun; Wu, Yulie; Xi, Xiang; Zhang, Yongmeng; Wu, Xuezhong

2017-01-01

The cylindrical resonator gyroscope (CRG) is a typical Coriolis vibratory gyroscope whose performance is mostly influenced by the damping characteristic of the cylindrical resonator. However, the tremendous damping influences caused by pasting piezoelectric electrodes on the gyroscope, which degrades the performance to a large extent, have rarely been studied. In this paper, the dynamical model is established to analyze various forms of energy consumption. In addition, a FE COMSOL model is also created to discuss the damping influences of several significant parameters of the adhesive layer and piezoelectric electrodes, respectively, and then explicit influence laws are obtained. Simulation results demonstrate that the adhesive layer has some impact on the damping characteristic, but it not significant. The Q factor decreases about 30.31% in total as a result of pasting piezoelectric electrodes. What is more, it is discovered that piezoelectric electrodes with short length, locations away from the outside edges, proper width and well-chosen thickness are able to reduce the damping influences to a large extent. Afterwards, experiments of testing the Q factor are set up to validate the simulation values. PMID:28471376

Monolithic integration of fine cylindrical glass microcapillaries on silicon for electrophoretic separation of biomolecules

PubMed Central

Cao, Zhen; Ren, Kangning; Wu, Hongkai; Yobas, Levent

2012-01-01

We demonstrate monolithic integration of fine cylindrical glass microcapillaries (diameter ∼1 μm) on silicon and evaluate their performance for electrophoretic separation of biomolecules. Such microcapillaries are achieved through thermal reflow of a glass layer on microstructured silicon whereby slender voids are moulded into cylindrical tubes. The process allows self-enclosed microcapillaries with a uniform profile. A simplified method is also described to integrate the microcapillaries with a sample-injection cross without the requirement of glass etching. The 10-mm-long microcapillaries sustain field intensities up to 90 kV/m and limit the temperature excursions due to Joule heating to a few degrees Celsius only. PMID:23874369

Colliding wall-jets on a cylindrical surface

NASA Astrophysics Data System (ADS)

Tesař, Václav; Peszynski, Kazimierz

2015-05-01

Paper discusses aerodynamics and potential engineering applications of an unusual and in literature practically unknown fluid flow configuration, with two wall-jets attached to a cylindrical surface so that they collide head-on and by mutual conjunction generate a single jet directed away from the wall. Applications are envisaged in pneumatic sensors, particularly those operating at low Reynolds numbers. Performed experimental investigation, combined with numerical flowfield computations, revealed several interesting aspects. The most interesting among them is the discovery of symmetry-breaking existence of three different stable flow regimes. This opens a possibility for fluidic tristable amplifiers and systems operating with ternary logic.

Flow regimes in a shallow rotating cylindrical annulus with temperature gradients imposed on the horizontal boundaries

NASA Technical Reports Server (NTRS)

Hathaway, D. H.; Fowlis, W. W.

1986-01-01

Experimental flow regime diagrams are determined for a new rotating cylindrical annulus configuration which permits a measure of control over the internal vertical temperature gradient. The new annulus has radial temperature gradients imposed on plane horizontal thermally conducting endwalls (with the cylindrical sidewalls as insulators) and is considered to be more relevant to atmospheric dynamics studies than the classical cylindrical annulus. Observations have revealed that, in addition to the axisymmetric flow and nonaxisymmetric baroclinic wave flow which occur in the classical annulus, two additional nonaxisymmetric flow types occur in the new annulus: boundary-layer thermal convection and deep thermal convection. Flow regime diagrams for three different values of the imposed vertical temperature difference are presented, and explanations for the flow transitions are offered. The new annulus provides scientific backup for the proposed Atmospheric General Circulation Experiment for Spacelab. The apparatus diagram is included.

Asymptotic analysis of the shear strain effect on the wave characteristics of a multilayered cylindrical shell filled with fluid

NASA Astrophysics Data System (ADS)

Amenzade, R. Yu.; Kiiko, I. A.

2007-06-01

It is commonly assumed that the theory based on the Kirchhoff hypotheses describes the properties inherent in the wave processes occurring in shells filled with fluids. But there are several new effects that cannot be described by this theory (in particular, the appearance of new types of waves). In this paper, we present a linearized description of axisymmetric wave motion of a perfect incompressible fluid in a multilayered cylindrical shell with allowance for shear strain; the shell is assumed to be infinite and simply supported. This description is aimed at finding new mechanical effects and hence at estimating the influence of the multiple layers and the shear strain on the wave characteristics. In a sense, it generalizes and develops well-known studies of this type. Practice necessitates deriving equations constructed under the assumption that the physical and mechanical properties of the shell material are inhomogeneous along the thickness direction or the shell is multilayered; the development of refined theories (compared with the classical theory based on the Kirchhoff—Love straight normal hypothesis) is also inspired by practice. This is primarily related to the fact that multilayered thin-walled shells made of composite materials are used in various fields of technology. It is of interest to note that, as a result of long evolution, the phenomenon of being multilayered also predominates in living organisms. For example, this is typical of big blood vessels [1] (arteries and veins). In [2], on the basis of a three-dimensional variational principle of mixed type, the equations of motion and physical relations for elastic anisotropic shells rigidly inhomogeneous in the thickness direction are derived under the assumptions of the theory of thin shells and with shear strains taken into account. It is also noted that the case of multilayered shells can be modeled by introducing functions with integrable singularities. When studying wave propagation in deformable shells containing fluid, hydroelasticity problems arise; the solution of such problems is of both theoretical and practical importance. Of topical problems in this field, problems related to pulsating blood flow in big blood vessels [3] (the theory of pulse waves) are worth mentioning. The incentive for such studies is that they can help to understand the normal operation of the blood circulatory system, predict its reaction to variations, and propose methods for artificial intervention. Thus, diagnostics, surgery, and prosthesis are closely related to biomechanics. But the applied value of such problems is not bounded by their applications in hemodynamics. They are also very important in technology because of the wide use of systems of fluid and gas transportation through pipelines with corrosion-resistant coating.

Bending Boundary Layers in Laminated-Composite Circular Cylindrical Shells

NASA Technical Reports Server (NTRS)

Nemeth, Michael P.; Smeltzer, Stanley S., III

2000-01-01

A study of the attenuation of bending boundary layers in balanced and unbalanced, symmetrically and unsymmetrically laminated cylindrical shells is presented for nine contemporary material systems. The analysis is based on the linear Sanders-Koiter shell equations and specializations to the Love-Kirchhoff shell equations and Donnell's equations are included. Two nondimensional parameters are identified that characterize the effects of laminate orthotropy and anisotropy on the bending boundary-layer decay length in a very general manner. A substantial number of structural design technology results are presented for a wide range of laminated-composite cylinders. For all laminates considered, the results show that the differences between results obtained with the Sanders-Koiter shell equations, the Love-Kirchhoff shell equations, and Donnell's equations are negligible. The results also show that the effect of anisotropy in the form of coupling between pure bending and twisting has a negligible effect on the size of the bending boundary-layer decay length of the balanced, symmetrically laminated cylinders considered. Moreover, the results show that coupling between the various types of shell anisotropies has a negligible effect on the calculation of the bending boundary-layer decay length in most cases. The results also show that, in some cases, neglecting the shell anisotropy results in underestimating the bending boundary-layer decay length and, in other cases, results in an overestimation.

Hydrogen generation utilizing integrated CO2 removal with steam reforming

DOEpatents

Duraiswamy, Kandaswamy; Chellappa, Anand S

2013-07-23

A steam reformer may comprise fluid inlet and outlet connections and have a substantially cylindrical geometry divided into reforming segments and reforming compartments extending longitudinally within the reformer, each being in fluid communication. With the fluid inlets and outlets. Further, methods for generating hydrogen may comprise steam reformation and material adsorption in one operation followed by regeneration of adsorbers in another operation. Cathode off-gas from a fuel cell may be used to regenerate and sweep the adsorbers, and the operations may cycle among a plurality of adsorption enhanced reformers to provide a continuous flow of hydrogen.

Spatially periodic patterns in rotating fluids: a new spin on the old "soup-can race"

NASA Astrophysics Data System (ADS)

Carnevali, Antonino; Carnevali, Dora; Christ, Jessica

2000-11-01

A student's investigation of the old "soup-can race" experiment revealed spatially periodic structures at the surface of the rotating fluid. To better observe this effect, the experiment was transferred to a test bench, where an electric motor was used to spin a cylindrical bottle, partially filled with fluids of varied densities, about its longitudinal axis. A photogate and event-counter software provided real-time measurements of the rotational frequency. Various cell-formation patterns were observed. Experimental results will be presented, and connections with the theory will be explored.

Large scale motions of multiple limit-cycle high Reynolds number annular and toroidal rotor/stator cavities

NASA Astrophysics Data System (ADS)

Bridel-Bertomeu, Thibault; Gicquel, L. Y. M.; Staffelbach, G.

2017-06-01

Rotating cavity flows are essential components of industrial applications but their dynamics are still not fully understood when it comes to the relation between the fluid organization and monitored pressure fluctuations. From computer hard-drives to turbo-pumps of space launchers, designed devices often produce flow oscillations that can either destroy the component prematurely or produce too much noise. In such a context, large scale dynamics of high Reynolds number rotor/stator cavities need better understanding especially at the flow limit-cycle or associated statistically stationary state. In particular, the influence of curvature as well as cavity aspect ratio on the large scale organization and flow stability at a fixed rotating disc Reynolds number is fundamental. To probe such flows, wall-resolved large eddy simulation is applied to two different rotor/stator cylindrical cavities and one annular cavity. Validation of the predictions proves the method to be suited and to capture the disc boundary layer patterns reported in the literature. It is then shown that in complement to these disc boundary layer analyses, at the limit-cycle the rotating flows exhibit characteristic patterns at mid-height in the homogeneous core pointing the importance of large scale features. Indeed, dynamic modal decomposition reveals that the entire flow dynamics are driven by only a handful of atomic modes whose combination links the oscillatory patterns observed in the boundary layers as well as in the core of the cavity. These fluctuations form macro-structures, born in the unstable stator boundary layer and extending through the homogeneous inviscid core to the rotating disc boundary layer, causing its instability under some conditions. More importantly, the macro-structures significantly differ depending on the configuration pointing the need for deeper understanding of the influence of geometrical parameters as well as operating conditions.

Analysis of the strength of sea gas pipelines of positive buoyancy conditioned by glaciation

NASA Astrophysics Data System (ADS)

Malkov, Venyamin; Kurbatova, Galina; Ermolaeva, Nadezhda; Malkova, Yulia; Petrukhin, Ruslan

2018-05-01

A technique for estimating the stress state of a gas pipeline laid along the seabed in northern latitudes in the presence of glaciation is proposed. It is assumed that the pipeline lies on the bottom of the seabed, but under certain conditions on the some part of the pipeline a glaciation is formed and the gas pipeline section in the place of glaciation can come off the ground due to the positive buoyancy of the ice. Calculation of additional stresses caused by bending of the pipeline is of practical interest for strength evaluation. The gas pipeline is a two-layer cylindrical shell of circular cross section. The inner layer is made of high-strength steel, the outer layer is made of reinforced ferroconcrete. The proposed methodology for calculating the gas pipeline for strength is based on the equations of the theory of shells. The procedure takes into account the effect of internal gas pressure, external pressure of sea water, the weight of two-layer gas pipeline and the weight of the ice layer. The lifting force created by the displaced fluid and the positive buoyancy of the ice is also taken into account. It is significant that the listed loads cause only two types of deformation of the gas pipeline: axisymmetric and antisymmetric. The interaction of the pipeline with the ground as an elastic foundation is not considered. The main objective of the research is to establish the fact of separation of part of the pipeline from the ground. The method of calculations of stresses and deformations occurring in a model sea gas pipeline is presented.

The Pawnee Sequence: Poroelastic Effects from Injection in Osage County, Oklahoma

NASA Astrophysics Data System (ADS)

Barbour, A. J.; Rubinstein, J. L.

2016-12-01

Aggregate multi-year records of wastewater injection in Oklahoma show that the strongest change in injection within 20 km of the 2016 M5.8 Pawnee strike-slip earthquake was in Osage County, where injection rates increased rapidly in late-2012 by nearly a factor of three above previous levels. After this increase, rates there declined steadily over two years to an average rate characteristic of all other injection wells in Pawnee and Noble Counties, remaining relatively constant until the beginning of the earthquake sequence. Here we test if poroelastic effects associated with this injection-rate transient can help explain the relative timing between peak injection rates and the beginning of the Pawnee sequence. Although the alternative hypothesis that regional-scale faults and fractures in critically stressed rock serve as fast-pathways for fluid diffusion cannot be ruled out, it appears to be difficult to reconcile based solely on injection data and space-time patterns for this seismic sequence. We simulate the cylindrically symmetric, transient strain and pore pressure fields for an injection-source time function emulating the injection history in a layered half-space in accordance with linear poroelasticity. In the simulation domain, injection occurs at depths of 1300 - 1900 m, into a homogeneous basal sedimentary reservoir representing the Arbuckle Group, overlying a semi-infinite layer representing granitic basement; we determined the hydraulic, elastic, and poroelastic properties of these layers from published literature. At the mainshock hypocenter, this numerical model predicts a delay between peak injection rates and pore pressure increase that is strongly dependent on hydraulic diffusivity; however, the duration is also controlled by the bulk elastic properties and the undrained Skempton's coefficient of the rock. Furthermore, because of fluid-strain coupling, pore pressures in the basement rock decrease during this delay period, which would tend to stabilize temporarily a critically stressed fault. Even though pore pressure diffusion is the dominant mechanism at play, poroelastic effects do affect the relative timing assuming a reasonable set of material parameters, even though strain rates in the basement are relatively low compared to rates in the Arbuckle layer (and above).

Rapid, conformal gas-phase formation of silica (SiO2) nanotubes from water condensates.

PubMed

Bae, Changdeuck; Kim, Hyunchul; Yang, Yunjeong; Yoo, Hyunjun; Montero Moreno, Josep M; Bachmann, Julien; Nielsch, Kornelius; Shin, Hyunjung

2013-07-07

An innovative atomic layer deposition (ALD) concept, with which nanostructures of water condensates with high aspect ratio at equilibrium in cylindrical nanopores can be transformed uniformly into silica (SiO2) at near room temperature and ambient pressure, has been demonstrated for the first time. As a challenging model system, we first prove the conversion of cylindrical water condensates in porous alumina membranes to silica nanotubes (NTs) by introducing SiCl4 as a metal reactant without involving any catalytic reaction. Surprisingly, the water NTs reproducibly transformed into silica NTs, where the wall thickness of the silica NTs deposited per cycle was found to be limited by the amount of condensed water, and it was on the orders of ten nanometers per cycle (i.e., over 50 times faster than that of conventional ALD). More remarkably, the reactions only took place for 10-20 minutes or less without vacuum-related equipment. The thickness of initially adsorbed water layers in cylindrical nanopores was indirectly estimated from the thickness of formed SiO2 layers. With systematic experimental designs, we tackle the classical Kelvin equation in the nanosized pores, and the role of van der Waals forces in the nanoscale wetting phenomena, which is a long-standing issue lacking experimental insight. Moreover, we show that the present strategy is likely generalized to other oxide systems such as TiO2. Our approach opens up a new avenue for ultra-simple preparation of porous oxides and allows for the room temperature formation of dielectric layers toward organic electronic and photovoltaic applications.

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

PubMed

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

2010-04-14

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

Experimental evidence of symmetry-breaking supercritical transition in pipe flow of shear-thinning fluids

NASA Astrophysics Data System (ADS)

Wen, Chaofan; Poole, Robert J.; Willis, Ashley P.; Dennis, David J. C.

2017-03-01

Experimental results reveal that the asymmetric flow of shear-thinning fluid through a cylindrical pipe, which was previously associated with the laminar-turbulent transition process, appears to have the characteristics of a nonhysteretic, supercritical instability of the laminar base state. Contrary to what was previously believed, classical transition is found to be responsible for returning symmetry to the flow. An absence of evidence of the instability in simulations (either linear or nonlinear) suggests that an element of physics is lacking in the commonly used rheological model for inelastic shear-thinning fluids. These unexpected discoveries raise new questions regarding the stability of these practically important fluids and how they can be successfully modeled.

Experimental results concerning centrifugal impeller excitations

NASA Technical Reports Server (NTRS)

Vance, J. M.; Landadio, F. J.

1980-01-01

The effect of working fluid on the dynamics of an impeller with radial vanes was investigated. The impeller was supported vertically from a very flexible quill shaft in order to produce a low critical speed, and to allow the fluid dynamic effects on the impeller to predominate. The shaft was supported from ball bearings, so that there was no possibility of oil whip from fluid film bearings as a destabilizing influence. The impeller was run both in the atmosphere, and submerged in working fluids contained in a cylindrical housing, open at the top. Variable speed was obtained with a dc gearmotor drive unit. The speed was measured with a proximity probe pulse tachometer and electronic digital counter.

Flow through internal elastic lamina affects shear stress on smooth muscle cells (3D simulations).

PubMed

Tada, Shigeru; Tarbell, John M

2002-02-01

We describe a three-dimensional numerical simulation of interstitial flow through the medial layer of an artery accounting for the complex entrance condition associated with fenestral pores in the internal elastic lamina (IEL) to investigate the fluid mechanical environment around the smooth muscle cells (SMCs) right beneath the IEL. The IEL was modeled as an impermeable barrier to water flow except for the fenestral pores, which were assumed to be uniformly distributed over the IEL. The medial layer was modeled as a heterogeneous medium composed of a periodic array of cylindrical SMCs embedded in a continuous porous medium representing the interstitial proteoglycan and collagen matrix. Depending on the distance between the IEL bottom surface and the upstream end of the proximal layer of SMCs, the local shear stress on SMCs right beneath the fenestral pore could be more than 10 times higher than that on the cells far removed from the IEL under the conditions that the fenestral pore diameter and area fraction of pores were kept constant at 1.4 microm and 0.05, respectively. Thus these proximal SMCs may experience shear stress levels that are even higher than endothelial cells exposed to normal blood flow (order of 10 dyn/cm(2)). Furthermore, entrance flow through fenestral pores alters considerably the interstitial flow field in the medial layer over a spatial length scale of the order of the fenestral pore diameter. Thus the spatial gradient of shear stress on the most superficial SMC is noticeably higher than computed for endothelial cell surfaces.

Energy dissipation in a finite volume of magnetic fluid

NASA Astrophysics Data System (ADS)

Bashtovoi, V.; Motsar, A.; Reks, A.

2017-06-01

This study is devoted to investigation of energy dissipation processes which happen in a magnetic fluid drop with compound magnet during its motion in cylindrical non magnetic container. The possibility of energy dissipation control by means of electromagnetic field is examined. It's found that a change of magnetic field of compound magnet can lead to both increase and decrease of oscillation decay time and relative damping factor can be varied in a range of ±35%.

Ringin' the water bell: dynamic modes of curved fluid sheets

NASA Astrophysics Data System (ADS)

Kolinski, John; Aharoni, Hillel; Fineberg, Jay; Sharon, Eran

2015-11-01

A water bell is formed by fluid flowing in a thin, coherent sheet in the shape of a bell. Experimentally, a water bell is created via the impact of a cylindrical jet on a flat surface. Its shape is set by the splash angle (the separation angle) of the resulting cylindrically symmetric water sheet. The separation angle is altered by adjusting the height of a lip surrounding the impact point, as in a water sprinkler. We drive the lip's height sinusoidally, altering the separation angle, and ringin' the water bell. This forcing generates disturbances on the steady-state water bell that propagate forward and backward in the fluid's reference frame at well-defined velocities, and interact, resulting in the emergence of an interference pattern unique to each steady-state geometry. We analytically model these dynamics by linearizing the amplitude of the bell's response about the underlying curved geometry. This simple model predicts the nodal structure over a wide range of steady-state water bell configurations and driving frequencies. Due to the curved water bell geometry, the nodal structure is quite complex; nevertheless, the predicted nodal structure agrees extremely well with the experimental data. When we drive the bell beyond perturbative separation angles, the nodal locations surprisingly persist, despite the strikingly altered underlying water bell shape. At extreme driving amplitudes the water sheet assumes a rich variety of tortuous, non-convex shapes; nevertheless, the fluid sheet remains intact.

Experimental and Numerical Studies of Mechanically- and Convectively-Driven Turbulence in Planetary Interiors

NASA Astrophysics Data System (ADS)

Grannan, Alexander Michael

2017-08-01

The energy for driving turbulent flows in planetary fluid layers comes from a combination of thermocompositional sources and the motion of the boundary in contact with the fluid through mechanisms like precessional, tidal, and librational forcing. Characterizing the resulting turbulent fluid motions are necessary for understanding many aspects of the planet's dynamics and evolution including the generation of magnetic fields in the electrically conducting fluid layers and dissipation in the oceans. Although such flows are strongly inertial they are also strongly influenced by the Coriolis force whose source is in the rotation of the body and tends to constrain the inertial effects and provide support for fluid instabilities that might in-turn generate turbulence. Furthermore, the magnetic fields generated by the electrically conducting fluids act back on the fluid through the Lorentz force that also tends to constrain the flow. The goal of this dissertation is to investigate the characteristics of turbulent flows under the influence of mechanical, convective, rotational and magnetic forcing. In order to investigate the response of the fluid to mechanical forcing, I have modified a unique set of laboratory experiments that allows me to quantify the generation of turbulence driven by the periodic oscillations of the fluid containing boundary through tides and libration. These laboratory experiments replicate the fundamental ingredients found in planetary environments and are necessary for the excitation of instabilities that drive the turbulent fluid motions. For librational forcing, a rigid ellipsoidal container and ellipsoidal shell of isothermal unstratified fluid is made to rotate with a superimposed oscillation while, for tidal forcing, an elastic ellipsoidal container of isothermal unstratified fluid is made to rotate while an independently rotating perturbance also flexes the elastic container. By varying the strength and frequencies of these oscillations the characteristics of the resulting turbulence are investigated using meridional views to identify the dominate modes and spatial location of the turbulence. For the first time, measurements of the velocity in the equatorial plane are coupled with high resolution numerical simulations of the full flow field in identical geometry to characterize the instability mechanism, energy deposited into the fluid layer, and long-term evolution of the flow. The velocities determined through laboratory and numerical simulations when extrapolated to planets allow me to argue that the dynamics of mechanical forcing in low viscosity fluids may an important role as new and potentially large source of dissipation in planetary interiors. To study convective forcing, I have modified and performed a set of rotating and non-rotating hydrodynamic convection experiments using water as well as rotating and non-rotating magnetohydrodynamic convection in gallium. These studies are performed in a cylindrical geometry representing a model of high latitude planetary core style convection wherein the axis of rotation and gravity are aligned. For the studies using water, the steady columns that are characteristic of rotating convection and present in the dynamo models are likely to destabilize at the more extreme planetary parameters giving way to transitions to more complex styles of rotating turbulent flow. In the studies of liquid metal where the viscosity is lower, the onset of rotating convection occurs through oscillatory columnar convection well below the onset of steady columns. Such oscillatory modes are not represented at the parameters used by current dynamo models. Furthermore a suite of laboratory experiments shows that the imposition of rotational forces and magnetic forces both separately and together generate zeroeth order flow transitions that change the fundamental convective modes and heat transfer. Such regimes are more easily accessible to laboratory experiments then to numerical simulations but demonstrate the need for a new generation of dynamo simulations capable of including the fundamental properties of liquid metals as are relevant for understanding the dynamics of planetary interiors.

Validation of a Computational Fluid Dynamics (CFD) Code for Supersonic Axisymmetric Base Flow

NASA Technical Reports Server (NTRS)

Tucker, P. Kevin

1993-01-01

The ability to accurately and efficiently calculate the flow structure in the base region of bodies of revolution in supersonic flight is a significant step in CFD code validation for applications ranging from base heating for rockets to drag for protectives. The FDNS code is used to compute such a flow and the results are compared to benchmark quality experimental data. Flowfield calculations are presented for a cylindrical afterbody at M = 2.46 and angle of attack a = O. Grid independent solutions are compared to mean velocity profiles in the separated wake area and downstream of the reattachment point. Additionally, quantities such as turbulent kinetic energy and shear layer growth rates are compared to the data. Finally, the computed base pressures are compared to the measured values. An effort is made to elucidate the role of turbulence models in the flowfield predictions. The level of turbulent eddy viscosity, and its origin, are used to contrast the various turbulence models and compare the results to the experimental data.

Scalar entrainment in the mixing layer

NASA Technical Reports Server (NTRS)

Sandham, N. D.; Mungal, M. G.; Broadwell, J. E.; Reynolds, W. C.

1988-01-01

New definitions of entrainment and mixing based on the passive scalar field in the plane mixing layer are proposed. The definitions distinguish clearly between three fluid states: (1) unmixed fluid, (2) fluid engulfed in the mixing layer, trapped between two scalar contours, and (3) mixed fluid. The difference betwen (2) and (3) is the amount of fluid which has been engulfed during the pairing process, but has not yet mixed. Trends are identified from direct numerical simulations and extensions to high Reynolds number mixing layers are made in terms of the Broadwell-Breidenthal mixing model. In the limit of high Peclet number (Pe = ReSc) it is speculated that engulfed fluid rises in steps associated with pairings, introducing unmixed fluid into the large scale structures, where it is eventually mixed at the Kolmogorov scale. From this viewpoint, pairing is a prerequisite for mixing in the turbulent plane mixing layer.

Hydrodynamic cavitation in Stokes flow of anisotropic fluids.

PubMed

Stieger, Tillmann; Agha, Hakam; Schoen, Martin; Mazza, Marco G; Sengupta, Anupam

2017-05-30

Cavitation, the nucleation of vapour in liquids, is ubiquitous in fluid dynamics, and is often implicated in a myriad of industrial and biomedical applications. Although extensively studied in isotropic liquids, corresponding investigations in anisotropic liquids are largely lacking. Here, by combining liquid crystal microfluidic experiments, nonequilibrium molecular dynamics simulations and theoretical arguments, we report flow-induced cavitation in an anisotropic fluid. The cavitation domain nucleates due to sudden pressure drop upon flow past a cylindrical obstacle within a microchannel. For an anisotropic fluid, the inception and growth of the cavitation domain ensued in the Stokes regime, while no cavitation was observed in isotropic liquids flowing under similar hydrodynamic parameters. Using simulations we identify a critical value of the Reynolds number for cavitation inception that scales inversely with the order parameter of the fluid. Strikingly, the critical Reynolds number for anisotropic fluids can be 50% lower than that of isotropic fluids.

Hydrodynamic cavitation in Stokes flow of anisotropic fluids

PubMed Central

Stieger, Tillmann; Agha, Hakam; Schoen, Martin; Mazza, Marco G.; Sengupta, Anupam

2017-01-01

Cavitation, the nucleation of vapour in liquids, is ubiquitous in fluid dynamics, and is often implicated in a myriad of industrial and biomedical applications. Although extensively studied in isotropic liquids, corresponding investigations in anisotropic liquids are largely lacking. Here, by combining liquid crystal microfluidic experiments, nonequilibrium molecular dynamics simulations and theoretical arguments, we report flow-induced cavitation in an anisotropic fluid. The cavitation domain nucleates due to sudden pressure drop upon flow past a cylindrical obstacle within a microchannel. For an anisotropic fluid, the inception and growth of the cavitation domain ensued in the Stokes regime, while no cavitation was observed in isotropic liquids flowing under similar hydrodynamic parameters. Using simulations we identify a critical value of the Reynolds number for cavitation inception that scales inversely with the order parameter of the fluid. Strikingly, the critical Reynolds number for anisotropic fluids can be 50% lower than that of isotropic fluids. PMID:28555615

Hydrodynamic cavitation in Stokes flow of anisotropic fluids

NASA Astrophysics Data System (ADS)

Stieger, Tillmann; Agha, Hakam; Schoen, Martin; Mazza, Marco G.; Sengupta, Anupam

2017-05-01

Cavitation, the nucleation of vapour in liquids, is ubiquitous in fluid dynamics, and is often implicated in a myriad of industrial and biomedical applications. Although extensively studied in isotropic liquids, corresponding investigations in anisotropic liquids are largely lacking. Here, by combining liquid crystal microfluidic experiments, nonequilibrium molecular dynamics simulations and theoretical arguments, we report flow-induced cavitation in an anisotropic fluid. The cavitation domain nucleates due to sudden pressure drop upon flow past a cylindrical obstacle within a microchannel. For an anisotropic fluid, the inception and growth of the cavitation domain ensued in the Stokes regime, while no cavitation was observed in isotropic liquids flowing under similar hydrodynamic parameters. Using simulations we identify a critical value of the Reynolds number for cavitation inception that scales inversely with the order parameter of the fluid. Strikingly, the critical Reynolds number for anisotropic fluids can be 50% lower than that of isotropic fluids.

Numerical Simulation of Cylindrical, Self-field MPD Thrusters with Multiple Propellants

NASA Technical Reports Server (NTRS)

Lapointe, Michael R.

1994-01-01

A two-dimensional, two-temperature, single fluid MHD code was used to predict the performance of cylindrical, self-field magnetoplasmadynamic (MPD) thrusters operated with argon, lithium, and hydrogen propellants. A thruster stability equation was determined relating maximum stable J(sup 2)/m values to cylindrical thruster geometry and propellant species. The maximum value of J(sup 2)/m was found to scale as the inverse of the propellant molecular weight to the 0.57 power, in rough agreement with limited experimental data which scales as the inverse square root of the propellant molecular weight. A general equation which relates total thrust to electromagnetic thrust, propellant molecular weight, and J(sup 2)/m was determined using reported thrust values for argon and hydrogen and calculated thrust values for lithium. In addition to argon, lithium, and hydrogen, the equation accurately predicted thrust for ammonia at sufficiently high J(sup 2)/m values. A simple algorithm is suggested to aid in the preliminary design of cylindrical, self-field MPD thrusters. A brief example is presented to illustrate the use of the algorithm in the design of a low power MPD thruster.

Cylindrical and spherical solitary waves in an electron-acoustic plasma with vortex electron distribution

NASA Astrophysics Data System (ADS)

Demiray, Hilmi; El-Zahar, Essam R.

2018-04-01

We consider the nonlinear propagation of electron-acoustic waves in a plasma composed of a cold electron fluid, hot electrons obeying a trapped/vortex-like distribution, and stationary ions. The basic nonlinear equations of the above described plasma are re-examined in the cylindrical (spherical) coordinates by employing the reductive perturbation technique. The modified cylindrical (spherical) KdV equation with fractional power nonlinearity is obtained as the evolution equation. Due to the nature of nonlinearity, this evolution equation cannot be reduced to the conventional KdV equation. A new family of closed form analytical approximate solution to the evolution equation and a comparison with numerical solution are presented and the results are depicted in some 2D and 3D figures. The results reveal that both solutions are in good agreement and the method can be used to obtain a new progressive wave solution for such evolution equations. Moreover, the resulting closed form analytical solution allows us to carry out a parametric study to investigate the effect of the physical parameters on the solution behavior of the modified cylindrical (spherical) KdV equation.

Desorption of water from hydrophilic MCM-41 mesopores: positron annihilation, FTIR and MD simulation studies.

PubMed

Maheshwari, Priya; Dutta, D; Muthulakshmi, T; Chakraborty, B; Raje, N; Pujari, P K

2017-02-08

The desorption mechanism of water from the hydrophilic mesopores of MCM-41 was studied using positron annihilation lifetime spectroscopy (PALS) and attenuated total reflection Fourier transform infrared spectroscopy supplemented with molecular dynamics (MD) simulation. PALS results indicated that water molecules do not undergo sequential evaporation in a simple layer-by-layer manner during desorption from MCM-41 mesopores. The results suggested that the water column inside the uniform cylindrical mesopore become stretched during desorption and induces cavitation (as seen in the case of ink-bottle type pores) inside it, keeping a dense water layer at the hydrophilic pore wall, as well as a water plug at both the open ends of the cylindrical pore, until the water was reduced to a certain volume fraction where the pore catastrophically empties. Before being emptied, the water molecules formed clusters inside the mesopores. The formation of molecular clusters below a certain level of hydration was corroborated by the MD simulation study. The results are discussed.

Helical Turing patterns in the Lengyel-Epstein model in thin cylindrical layers

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

Bánsági, T.; Taylor, A. F., E-mail: A.F.Taylor@sheffield.ac.uk

2015-06-15

The formation of Turing patterns was investigated in thin cylindrical layers using the Lengyel-Epstein model of the chlorine dioxide-iodine-malonic acid reaction. The influence of the width of the layer W and the diameter D of the inner cylinder on the pattern with intrinsic wavelength l were determined in simulations with initial random noise perturbations to the uniform state for W < l/2 and D ∼ l or lower. We show that the geometric constraints of the reaction domain may result in the formation of helical Turing patterns with parameters that give stripes (b = 0.2) or spots (b = 0.37) in two dimensions. For b = 0.2, the helices weremore » composed of lamellae and defects were likely as the diameter of the cylinder increased. With b = 0.37, the helices consisted of semi-cylinders and the orientation of stripes on the outer surface (and hence winding number) increased with increasing diameter until a new stripe appeared.« less

Sound transmission through double cylindrical shells lined with porous material under turbulent boundary layer excitation

NASA Astrophysics Data System (ADS)

Zhou, Jie; Bhaskar, Atul; Zhang, Xin

2015-11-01

This paper investigates sound transmission through double-walled cylindrical shell lined with poroelastic material in the core, excited by pressure fluctuations due to the exterior turbulent boundary layer (TBL). Biot's model is used to describe the sound wave propagating in the porous material. Three types of constructions, bonded-bonded, bonded-unbonded and unbonded-unbonded, are considered in this study. The power spectral density (PSD) of the inner shell kinetic energy is predicted for two turbulent boundary layer models, different air gap depths and three types of polyimide foams, respectively. The peaks of the inner shell kinetic energy due to shell resonance, hydrodynamic coincidence and acoustic coincidence are discussed. The results show that if the frequency band over the ring frequency is of interest, an air gap, even if very thin, should exist between the two elastic shells for better sound insulation. And if small density foam has a high flow resistance, a superior sound insulation can still be maintained.

Three-step cylindrical seal for high-performance turbomachines

NASA Technical Reports Server (NTRS)

Hendricks, Robert C.

1987-01-01

A three-step cylindrical seal configuration representing the seal for a high performance turbopump (e.g., the space shuttle main engine fuel pump) was tested under static (nonrotating) conditions. The test data included critical mass flux and pressure profiles over a wide range of inlet temperatures and pressures for fluid nitrogen and fluid hydrogen with the seal in concentric and fully eccentric positions. The critical mass flux (leakage rate) was 70% that of an equivalent straight cylindrical seal with a correspondingly higher pressure drop based on the same flow areas of 0.3569 sq cm but 85% that of the straight seal based on the third-step flow area of 0.3044 sq cm. The mass flow rates for the three step cylindrical seal in the fully eccentric and concentric positions were essentially the same, and the trends in flow coefficient followed those of a simple axisymmetric inlet configuration. However, for inlet stagnation temperatures less than the thermodynamic critical temperature the pressure profiles exhibited a flat region throughout the third step of the seal, with the pressure magnitude dependent on the inlet stagnation temperature. Such profiles represent an extreme positive direct stiffness. These conditions engendered a crossover in the pressure profile upstream of the postulated choke that resulted in a local negative stiffness. Flat and crossover profiles resulting from choking within the seal are practically unknown to the seal designer. However, they are of critical importance to turbomachine stability and must be integrated into any dynamic analysis of a seal of this configuration. In addition, choking is highly dependent on geometry, inlet-to-backpressure ratio, and inlet temperature and can occur within the seal even though the backpressure is above the critical pressure.

Soft Plumbing: Direct-Writing and Controllable Perfusion of Tubular Soft Materials

NASA Astrophysics Data System (ADS)

Guenther, Axel; Omoruwa, Patricia; Chen, Haotian; McAllister, Arianna; Jeronimo, Mark; Malladi, Shashi; Hakimi, Navid; Cao, Li; Ramchandran, Arun

2016-11-01

Tubular and ductular structures are abundant in tissues in a wide variety of diameters, wall thicknesses, and compositions. In spite of their relevance to engineered tissues, organs-on-chips and soft robotics, the rapid and consistent preparation of tubular structures remains a challenge. Here, we use a microfabricated printhead to direct-write biopolymeric tubes with dimensional and compositional control. A biopolymer solution is introduced to the center layer of the printhead, and the confining fluids to the top and the bottom layers. The radially flowing biopolymer solution is sandwiched between confining solutions that initiate gelation, initially assuming the shape of a funnel until emerging through a cylindrical confinement as a continuous biopolymer tube. Tubular constructs of sodium alginate and collagen I were obtained with inner diameters (0.6-2.2mm) and wall thicknesses (0.1-0.4mm) in favorable agreement with predictions of analytical models. We obtained homogeneous tubes with smooth and buckled walls and heterotypic constructs that possessed compositions that vary along the tube circumference or radius. Ductular soft materials were reversibly hosted in 3D printed fluidic devices for the perfusion at well-defined transmural pressures to explore the rich variety of dynamical features associated with collapsible tubes that include buckling, complete collapse, and self-oscillation.

RELIABLE RADIOGRAPHIC INSPECTION OF FLEXIBLE RISERS FOR THE OIL INDUSTRY

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

Almeida, Romulo M.; Rebello, Joao Marcos A.; Vaz, Murilo A.

2010-02-22

Flexible risers are composite tubular structures manufactured by the concentric assemblage of cylindrical polymeric and helically wound metallic layers employed to convey pressurized fluids such as oil, gas and water in the ocean environment. The metallic layers account for the flexible risers' structural strength and are dimensioned according to the static and dynamic loads. They are usually installed in a free hanging catenary configuration and are subjected to the direct action of waves and marine currents and wave induced motions from the oil production platform. The fatigue rupture of wire armours in the end fitting or within the riser segmentmore » protected by the bend stiffener is an object of major concern. Integrity models have been developed, however inspection techniques are mandatory to ensure that failure is detected. Gammagraphy has been used as a common inspection technique in all regions of the flexible riser, mainly with the single wall-single view method. On the other side, there is not any qualified radiographic procedure to this kind of structure. Radiographic simulation was adopted and its validation with actual gammagraphies and establishment of radiographic parameters to complex radiation geometries were done. Results show the viability of the radiographic inspection analyzing the armour wires' rupture and the displacement between wires.« less

Reliable Radiographic Inspection of Flexible Risers for the Oil Industry

NASA Astrophysics Data System (ADS)

Almeida, Rômulo M.; Rebello, Joao Marcos A.; Vaz, Murilo A.

2010-02-01

Flexible risers are composite tubular structures manufactured by the concentric assemblage of cylindrical polymeric and helically wound metallic layers employed to convey pressurized fluids such as oil, gas and water in the ocean environment. The metallic layers account for the flexible risers' structural strength and are dimensioned according to the static and dynamic loads. They are usually installed in a free hanging catenary configuration and are subjected to the direct action of waves and marine currents and wave induced motions from the oil production platform. The fatigue rupture of wire armours in the end fitting or within the riser segment protected by the bend stiffener is an object of major concern. Integrity models have been developed, however inspection techniques are mandatory to ensure that failure is detected. Gammagraphy has been used as a common inspection technique in all regions of the flexible riser, mainly with the single wall-single view method. On the other side, there is not any qualified radiographic procedure to this kind of structure. Radiographic simulation was adopted and its validation with actual gammagraphies and establishment of radiographic parameters to complex radiation geometries were done. Results show the viability of the radiographic inspection analyzing the armour wires' rupture and the displacement between wires.

Fluid-structure interaction in Taylor-Couette flow

NASA Astrophysics Data System (ADS)

Kempf, Martin Horst Willi

1998-10-01

The linear stability of a viscous fluid between two concentric, rotating cylinders is considered. The inner cylinder is a rigid boundary and the outer cylinder has an elastic layer exposed to the fluid. The subject is motivated by flow between two adjoining rollers in a printing press. The governing equations of the fluid layer are the incompressible Navier-Stokes equations, and the governing equations of the elastic layer are Navier's equations. A narrow gap, neutral stability, and axisymmetric disturbances are assumed. The solution involves a novel technique for treating two layer stability problems, where an exact solution in the elastic layer is used to isolate the problem in the fluid layer. The results show that the presence of the elastic layer has only a slight effect on the critical Taylor numbers for the elastic parameters of modern printing presses. However, there are parameter values where the critical Taylor number is dramatically different than the classical Taylor-Couette problem.

SCB initiator

DOEpatents

Bickes Jr., Robert W.; Renlund, Anita M.; Stanton, Philip L.

1994-11-01

A detonator for high explosives initiated by mechanical impact includes a cylindrical barrel, a layer of flyer material mechanically covering the barrel at one end, and a semiconductor bridge ignitor including a pair of electrically conductive pads connected by a semiconductor bridge. The bridge is in operational contact with the layer, whereby ignition of said bridge forces a portion of the layer through the barrel to detonate the explosive. Input means are provided for igniting the semiconductor bridge ignitor.

SCB initiator

DOEpatents

Bickes, Jr., Robert W.; Renlund, Anita M.; Stanton, Philip L.

1994-01-01

A detonator for high explosives initiated by mechanical impact includes a cylindrical barrel, a layer of flyer material mechanically covering the barrel at one end, and a semiconductor bridge ignitor including a pair of electrically conductive pads connected by a semiconductor bridge. The bridge is in operational contact with the layer, whereby ignition of said bridge forces a portion of the layer through the barrel to detonate the explosive. Input means are provided for igniting the semiconductor bridge ignitor.

Improved sample management in the cylindrical-tube microelectrophoresis method

NASA Technical Reports Server (NTRS)

Smolka, A. J. K.

1980-01-01

A modification to an analytical microelectrophoresis system is described that improves the manipulation of the sample particles and fluid. The apparatus modification and improved operational procedure should yield more accurate measurements of particle mobilities and permit less skilled operators to use the apparatus.

Monitoring Coating Thickness During Plasma Spraying

NASA Technical Reports Server (NTRS)

Miller, Robert A.

1990-01-01

High-resolution video measures thickness accurately without interfering with process. Camera views cylindrical part through filter during plasma spraying. Lamp blacklights part, creating high-contrast silhouette on video monitor. Width analyzer counts number of lines in image of part after each pass of spray gun. Layer-by-layer measurements ensure adequate coat built up without danger of exceeding required thickness.

The numerical approach adopted in toba computer code for mass and heat transfer dynamic analysis of metal hydride hydrogen storage beds

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

El Osery, I.A.

1983-12-01

Modelling studies of metal hydride hydrogen storage beds is a part of an extensive R and D program conducted in Egypt on hydrogen energy. In this context two computer programs; namely RET and RET1; have been developed. In RET computer program, a cylindrical conduction bed model is considered and an approximate analytical solution is used for solution of the associated mass and heat transfer problem. This problem is solved in RET1 computer program numerically allowing more flexibility in operating conditions but still limited to cylindrical configuration with only two alternatives for heat exchange; either fluid is passing through tubes imbeddedmore » in the solid alloy matrix or solid rods are surrounded by annular fluid tubes. The present computer code TOBA is more flexible and realistic. It performs the mass and heat transfer dynamic analysis of metal hydride storage beds using a variety of geometrical and operating alternatives.« less

Exact solution for the layered convection of a viscous incompressible fluid at specified temperature gradients and tangential forces on the free boundary

NASA Astrophysics Data System (ADS)

Burmasheva, N. V.; Prosviryakov, E. Yu.

2017-12-01

A new exact analytical solution of a system of thermal convection equations in the Boussinesq approximation describing layered flows in an incompressible viscous fluid is obtained. A fluid flow in an infinite layer is considered. Convection in the fluid is induced by tangential stresses specified on the upper non-deformable boundary. At the fixed lower boundary, the no-slip condition is satisfied. Temperature corrections are given on the both boundaries of the fluid layer. The possibility of physical field stratification is investigated.

Heat transport and coupling modes in Rayleigh-Bénard convection occurring between two layers with largely different viscosities

NASA Astrophysics Data System (ADS)

Yoshida, Masaki; Iwamori, Hikaru; Hamano, Yozo; Suetsugu, Daisuke

2017-09-01

A high-resolution numerical simulation model in two-dimensional cylindrical geometry was used to discuss the heat transport and coupling modes in two-layer Rayleigh-Bénard convection with a high Rayleigh number (up to the order of 109), an infinite Prandtl number, and large viscosity contrasts (up to 10-3) between an outer, highly viscous layer (HVL) and an inner, low-viscosity layer (LVL). In addition to mechanical and thermal interaction across the HVL-LVL interface, which has been investigated by Yoshida and Hamano ["Numerical studies on the dynamics of two-layer Rayleigh-Bénard convection with an infinite Prandtl number and large viscosity contrasts," Phys. Fluids 28(11), 116601 (2016)], the spatiotemporal analysis in this study provides new insights into (1) heat transport over the entire system between the bottom of the LVL and the top of the HVL, in particular that associated with thermal plumes, and (2) the convection regime and coupling mode of the two layers, including the transition mechanism between the mechanical coupling mode at relatively low viscosity contrasts and the thermal coupling mode at higher viscosity contrasts. Although flow in the LVL is highly time-dependent, it shares the spatially opposite/same flow pattern synchronized to the nearly stationary upwelling and downwelling plumes in the HVL, corresponding to the mechanical/thermal coupling mode. In the transitional regime between the mechanical and thermal coupling modes, the LVL exhibits periodical switching between the two phases (i.e., the mechanical and thermal coupling phases) with a stagnant period. A detailed inspection revealed that the switching was initiated by the instability in the uppermost boundary layer of the LVL. These results suggest that convection in the highly viscous mantle of the Earth controls that of the extremely low-viscosity outer core in a top-down manner under the thermal coupling mode, which may support a scenario of top-down hemispherical dynamics proposed by the recent geochemical study.

Optimization and development of a core-in-cup tablet for modulated release of theophylline in simulated gastrointestinal fluids.

PubMed

Danckwerts, M P

2000-07-01

A triple-layer core-in-cup tablet that can release theophylline in simulated gastrointestinal (GI) fluids at three distinct rates has been developed. The first layer is an immediate-release layer; the second layer is a sustained-release layer; and the last layer is a boost layer, which was designed to coincide with a higher nocturnal dose of theophylline. The study consisted of two stages. The first stage optimized the sustained-release layer of the tablet to release theophylline over a period of 12 hr. Results from this stage indicated that 30% w/w acacia gum was the best polymer and concentration to use when compressed to a hardness of 50 N/m2. The second stage of the study involved the investigation of the final triple-layer core-in-cup tablet to release theophylline at three different rates in simulated GI fluids. The triple-layer modulated core-in-cup tablet successfully released drug in simulated fluids at an initial rate of 40 mg/min, followed by a rate of 0.4085 mg/min, in simulated gastric fluid TS, 0.1860 mg/min in simulated intestinal fluid TS, and finally by a boosted rate of 0.6952 mg/min.

Plume Splitting in a Two-layer Stratified Ambient Fluid

NASA Astrophysics Data System (ADS)

Ma, Yongxing; Flynn, Morris; Sutherland, Bruce

2017-11-01

A line-source plume descending into a two-layer stratified ambient fluid in a finite sized tank is studied experimentally. Although the total volume of ambient fluid is fixed, lower- and upper-layer fluids are respectively removed and added at a constant rate mimicking marine outfall through diffusers and natural and hybrid ventilated buildings. The influence of the plume on the ambient depends on the value of λ, defined as the ratio of the plume buoyancy to the buoyancy loss of the plume as it crosses the ambient interface. Similar to classical filling-box experiments, the plume can always reach the bottom of the tank if λ > 1 . By contrast, if λ < 1 , an intermediate layer eventually forms as a result of plume splitting. Eventually all of the plume fluid spreads within the intermediate layer. The starting time, tv, and the ending time, tt, of the transition process measured from experiments correlate with the value of λ. A three-layer ambient fluid is observed after transition, and the mean value of the measured densities of the intermediate layer fluid is well predicted using plume theory. Acknowledgments: Funding for this study was provided by NSERC.

Modulational instability: Conservation laws and bright soliton solution of ion-acoustic waves in electron-positron-ion-dust plasmas

NASA Astrophysics Data System (ADS)

EL-Kalaawy, O. H.

2018-02-01

We consider the nonlinear propagation of non-planar (cylindrical and spherical) ion-acoustic (IA) envelope solitary waves in an unmagnetized plasma consisting of electron-positron-ion-dust plasma with two-electron temperature distributions in the context of the non-extensive statistics. The basic set of fluid equations is reduced to the modified nonlinear Schrödinger (MNLS) equation in cylindrical and spherical geometry by using the reductive perturbation method (RPM). It is found that the nature of the modulational instabilities would be significantly modified due to the effects of the non-extensive and other plasma parameters as well as cylindrical and spherical geometry. Conservation laws of the MNLS equation are obtained by Lie symmetry and multiplier method. A new exact solution (envelope bright soliton) is obtained by the extended homogeneous balance method. Finally, we study the results of this article.

Explosion resistant insulator and method of making same

DOEpatents

Meyer, Jeffry R.; Billings, Jr., John S.; Spindle, Harvey E.; Hofmann, Charles F.

1983-01-01

An electrical insulator assembly and method of manufacturing same, having a generally cylindrical or conical body portion formed of a breakable cast solid insulation system and a reinforcing member having a corrugated configuration and formed of a web or mesh type reinforcing fabric. When the breakable body member has been broken, the corrugated configured reinforcing web member provides a path of escape for pressurized insulating fluid while limiting the movement of body member fragments in the direction of escape of the pressurized fluid.

TEMPEST/N33.5. Computational Fluid Dynamics Package For Incompressible, 3D, Time Dependent Pro

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

Trent, Dr.D.S.; Eyler, Dr.L.L.

TEMPESTN33.5 provides numerical solutions to general incompressible flow problems with coupled heat transfer in fluids and solids. Turbulence is created with a k-e model and gas, liquid or solid constituents may be included with the bulk flow. Problems may be modeled in Cartesian or cylindrical coordinates. Limitations include incompressible flow, Boussinesq approximation, and passive constituents. No direct steady state solution is available; steady state is obtained as the limit of a transient.

Multiple scattering by infinitely long cylindrical glass inclusions in a saturated Biot porous medium of glass beads.

PubMed

Trabelsi, W; Franklin, H; Tinel, A

2016-05-01

The resonance spectrum of sets of two to five infinitely long parallel cylindrical glass inclusions in a fluid saturated porous matrix of unconsolidated glass beads is investigated. The ratio of bead diameters to inclusion diameters is 1/5. The far field form functions and the related phase derivatives are calculated by using an exact multiple scattering formalism and by assuming that the porous medium obeys Biot's model. In order to validate this hypothesis, comparisons between theory and experiments are done in the special case of a fast incident wave on a set of two and three inclusions.

Solar energy collection system

NASA Technical Reports Server (NTRS)

Miller, C. G.; Stephens, J. B. (Inventor)

1979-01-01

A fixed, linear, ground-based primary reflector having an extended curved sawtooth-contoured surface covered with a metalized polymeric reflecting material, reflects solar energy to a movably supported collector that is kept at the concentrated line focus reflector primary. The primary reflector may be constructed by a process utilizing well known freeway paving machinery. The solar energy absorber is preferably a fluid transporting pipe. Efficient utilization leading to high temperatures from the reflected solar energy is obtained by cylindrical shaped secondary reflectors that direct off-angle energy to the absorber pipe. A seriatim arrangement of cylindrical secondary reflector stages and spot-forming reflector stages produces a high temperature solar energy collection system of greater efficiency.

Numerical simulation of heat transfer in power law fluid flow through a stenosed artery

NASA Astrophysics Data System (ADS)

Talib, Amira Husni; Abdullah, Ilyani

2017-11-01

A numerical study of heat transfer in a power law fluid is investigated in this paper. The blood flow is treated as power law fluid with a presence of cosine shaped stenosis. This study reveals the effect of stenosis on the heat transfer and velocity of blood flowing in the constricted artery. The governing and energy equations are formulated in a cylindrical coordinate system. Hence, the set of equations and boundary conditions are solved numerically by Marker and Cell (MAC) method. The graphical result shows the profile of blood temperature is increased while the blood velocity is decreased at the critical height of stenosis.

Microstructure and properties of aluminium-aluminium oxide graded composite materials

NASA Astrophysics Data System (ADS)

Kamaruzaman, F. F.; Nuruzzaman, D. M.; Ismail, N. M.; Hamedon, Z.; Iqbal, A. K. M. A.; Azhari, A.

2018-03-01

In this research works, four-layered aluminium-aluminium oxide (Al-Al2O3) graded composite materials were fabricated using powder metallurgy (PM) method. In processing, metal-ceramic graded composite materials of 0%, 10%, 20% and 30% weight percentage of ceramic concentration were prepared under 30 ton compaction load using a cylindrical die-punch set made of steel. After that, two-step pressureless sintering was carried out at sintering temperature and time 600°C and 3 hours respectively. It was observed that the sintered cylindrical specimens of 30 mm diameter were prepared successfully. The graded composite specimens were analysed and the properties such as density, microstructure and hardness were measured. It was found that after sintering process, the diameter of the graded cylindrical structure was decreased. Using both Archimedes method and rule of mixture (ROM), he density of structure was measured. The obtained results revealed that the microvickers hardness was increased as the ceramic component increases in the graded layer. Moreover, it was observed that the interface of the graded structure is clearly distinguished within the multilayer stack and the ceramic particles are almost uniformly distributed in the Al matrix.

Bending Boundary Layers in Laminated-Composite Circular Cylindrical Shells

NASA Technical Reports Server (NTRS)

Nemeth, Michael P.; Smeltzer, Stanley S., III

2000-01-01

An analytical, parametric study of the attenuation of bending boundary layers or edge effects in balanced and unbalanced, symmetrically and unsymmetrically laminated thin cylindrical shells is presented for nine contemporary material systems. The analysis is based on the linear Sanders-Koiter shell equations and specializations to the Love-Kirchhoff shell equations and Donnell's equations are included. Two nondimensional parameters are identified that characterize and quantify the effects of laminate orthotropy and laminate anisotropy on the bending boundary-layer decay length in a very general and encompassing manner. A substantial number of structural design technology results are presented for a wide range of laminated-composite cylinders. For all the laminate constructions considered, the results show that the differences between results that were obtained with the Sanders-Koiter shell equations, the Love-Kirchhoff shell equations, and Donnell's equations are negligible. The results also show that the effect of anisotropy in the form of coupling between pure bending and twisting has a negligible effect on the size of the bending boundary-layer decay length of the balanced, symmetrically laminated cylinders considered. Moreover, the results show that coupling between the various types of shell anisotropies has a negligible effect on the calculation of the bending boundary-layer decay length in most cases. The results also show that in some cases neglecting the shell anisotropy results in underestimating the bending boundary-layer decay length and in other cases it results in an overestimation.

Computer Program for the Calculation of Multicomponent Convective Diffusion Deposition Rates from Chemically Frozen Boundary Layer Theory

NASA Technical Reports Server (NTRS)

Gokoglu, S. A.; Chen, B. K.; Rosner, D. E.

1984-01-01

The computer program based on multicomponent chemically frozen boundary layer (CFBL) theory for calculating vapor and/or small particle deposition rates is documented. A specific application to perimter-averaged Na2SO4 deposition rate calculations on a cylindrical collector is demonstrated. The manual includes a typical program input and output for users.

Electroelastic fields in a layered piezoelectric cylindrical shell under dynamic load

NASA Astrophysics Data System (ADS)

Saviz, M. R.; Shakeri, M.; Yas, M. H.

2007-10-01

The objective of this paper is to demonstrate layerwise theory for the analysis of thick laminated piezoelectric shell structures. A general finite element formulation using the layerwise theory is developed for a laminated cylindrical shell with piezoelectric layers, subjected to dynamic loads. The quadratic approximation of the displacement and electric potential in the thickness direction is considered. The governing equations are reduced to two-dimensional (2D) differential equations. The three-dimensional (3D) elasticity solution is also presented. The resulting equations are solved by a proper finite element method. The numerical results for static loading are compared with exact solutions of benchmark problems. Numerical examples of the dynamic problem are presented. The convergence is studied, as is the influence of the electromechanical coupling on the axisymmetric free-vibration characteristics of a thick cylinder.

Modeling electrical double-layer effects for microfluidic impedance spectroscopy from 100 kHz to 110 GHz.

PubMed

Little, Charles A E; Orloff, Nathan D; Hanemann, Isaac E; Long, Christian J; Bright, Victor M; Booth, James C

2017-07-25

Broadband microfluidic-based impedance spectroscopy can be used to characterize complex fluids, with applications in medical diagnostics and in chemical and pharmacological manufacturing. Many relevant fluids are ionic; during impedance measurements ions migrate to the electrodes, forming an electrical double-layer. Effects from the electrical double-layer dominate over, and reduce sensitivity to, the intrinsic impedance of the fluid below a characteristic frequency. Here we use calibrated measurements of saline solution in microfluidic coplanar waveguide devices at frequencies between 100 kHz and 110 GHz to directly measure the double-layer admittance for solutions of varying ionic conductivity. We successfully model the double-layer admittance using a combination of a Cole-Cole response with a constant phase element contribution. Our analysis yields a double-layer relaxation time that decreases linearly with solution conductivity, and allows for double-layer effects to be separated from the intrinsic fluid response and quantified for a wide range of conducting fluids.

The formation of spikes in the displacement of miscible fluids

NASA Technical Reports Server (NTRS)

Rashidnia, N.; Balasubramaniam, R.; Schroer, R. T.

2004-01-01

We report on experiments in which a more viscous fluid displaces a less viscous one in a vertical cylindrical tube. These experiments were performed using silicone oils in a vertical pipette of small diameter. The more viscous fluid also had a slightly larger density than the less viscous fluid. In the initial configuration, the fluids were at rest, and the interface was nominally flat. A dye was added to the more viscous fluid for ease of observation of the interface between the fluids. The flow was initiated by pumping the more viscous fluid into the less viscous one. The displacement velocity was such that the Reynolds number was smaller than unity and the Peclet number for mass transfer between the fluids was large compared to unity. For upward displacement of the more viscous fluid from an initially stable configuration, an axisymmetric finger was observed under all conditions. However, a needle-shaped spike was seen to propagate from the main finger in many cases, similar to that observed by Petitjeans and Maxworthy for the displacement of a more viscous fluid by a less viscous one.

Microliter-sized ionization device and method

NASA Technical Reports Server (NTRS)

Simac, Robert M. (Inventor); Wernlund, Roger F. (Inventor); Cohen, Martin J. (Inventor)

1999-01-01

A microliter-sized metastable ionization device with a cavity, a sample gas inlet, a corona gas inlet and a gas outlet. A first electrode has a hollow and disposed in the cavity and is in fluid communication with the sample gas inlet. A second electrode is in fluid communication with the corona gas inlet and is disposed around the first electrode adjacent the hollow end thereof. A gap forming means forms a corona gap between the first and second electrodes. A first power supply is connected to the first electrode and the second power supply is connected to the second electrode for generating a corona discharge across the corona gap. A collector has a hollow end portion disposed in the cavity which is in fluid communications with the gas outlet for the outgassing and detection of ionized gases. The first electrode can be a tubular member aligned concentrically with a cylindrical second electrode. The gap forming means can be in annular disc projecting radially inwardly from the cylindrical second electrode. The collector can have a tubular opening aligned coaxially with the first electrode and has an end face spaced a short distance from an end face of the first electrode forming a small active volume therebetween for the generation and detection of small quantities of trace analytes.

The methodology of preparing the end faces of cylindrical waveguide of polydimethylsiloxane

NASA Astrophysics Data System (ADS)

Novak, M.; Nedoma, J.; Jargus, J.; Bednarek, L.; Cvejn, D.; Vasinek, V.

2017-10-01

Polydimethylsiloxane (PDMS) can be used for its optical properties and its composition offers the possibility of use in the dangerous environments. Therefore authors of this article focused on more detailed working with this material. The article describes the methodology of preparing the end faces of the cylindrical waveguide of polymer polydimethylsiloxane (PDMS) to minimize losses during joining. The first method of preparing the end faces of the cylindrical waveguide of polydimethylsiloxane is based on the polishing surface of the sandpaper of different sizes of grains (3 species). The second method using so-called heat smoothing and the third method using aligning end faces by a new layer of polydimethylsiloxane. The outcome of the study is to evaluate the quality of the end faces of the cylindrical waveguide of polymer polydimethylsiloxane based on evaluating the attenuation. For this experiment, it was created a total of 140 samples. The attenuation was determined from both sides of the created samples for three different wavelengths of the visible spectrum.

Fuselage boundary-layer refraction of fan tones radiated from an installed turbofan aero-engine.

PubMed

Gaffney, James; McAlpine, Alan; Kingan, Michael J

2017-03-01

A distributed source model to predict fan tone noise levels of an installed turbofan aero-engine is extended to include the refraction effects caused by the fuselage boundary layer. The model is a simple representation of an installed turbofan, where fan tones are represented in terms of spinning modes radiated from a semi-infinite circular duct, and the aircraft's fuselage is represented by an infinitely long, rigid cylinder. The distributed source is a disk, formed by integrating infinitesimal volume sources located on the intake duct termination. The cylinder is located adjacent to the disk. There is uniform axial flow, aligned with the axis of the cylinder, everywhere except close to the cylinder where there is a constant thickness boundary layer. The aim is to predict the near-field acoustic pressure, and in particular, to predict the pressure on the cylindrical fuselage which is relevant to assess cabin noise. Thus no far-field approximations are included in the modelling. The effect of the boundary layer is quantified by calculating the area-averaged mean square pressure over the cylinder's surface with and without the boundary layer included in the prediction model. The sound propagation through the boundary layer is calculated by solving the Pridmore-Brown equation. Results from the theoretical method show that the boundary layer has a significant effect on the predicted sound pressure levels on the cylindrical fuselage, owing to sound radiation of fan tones from an installed turbofan aero-engine.

Comparison of several classical density functional theories for the adsorption of flexible chain molecules into cylindrical nanopores.

PubMed

Hlushak, S P; Cummings, P T; McCabe, C

2013-12-21

Adsorption of flexible oligomers into narrow cylindrical pores has been studied by means of several versions of classical density functional theory (CDFT) and Monte Carlo simulation. The adsorption process is interesting to study due to the competition between the entropic depletion of oligomers from the pores and the wall-oligomer attraction. It is also challenging to describe using current CDFTs, which tend to overestimate the amount of the adsorbed fluid. From a comparison of several different CDFT approaches, we find that this is due to the assumption of ideal or freely jointed chain conformations. Moreover, it is demonstrated that it is impossible to obtain a reasonable description of the adsorption isotherms without taking into account accurate contact values in the distribution functions describing the structure of the reference monomer fluid. At low densities, more accurate result are obtained in comparison with Monte Carlo simulation data when accurate contact values are incorporated into the theory rather than the more commonly used hard-sphere contact value. However, even the CDFT with accurate contact values still overestimates the amount of the adsorbed fluid due to the ideal or freely jointed chain approximation, used for the description of chain conformations in most CDFT approaches. We find that significant improvement can achieved by employing self-consistent field theory, which samples self-avoiding chain conformations and decreases the number of possible chain conformations, and, consequently, the amount of the adsorbed fluid.

Global chaotization of fluid particle trajectories in a sheared two-layer two-vortex flow.

PubMed

Ryzhov, Evgeny A; Koshel, Konstantin V

2015-10-01

In a two-layer quasi-geostrophic approximation, we study the irregular dynamics of fluid particles arising due to two interacting point vortices embedded in a deformation flow consisting of shear and rotational components. The two vortices are arranged within the bottom layer, but an emphasis is on the upper-layer fluid particle motion. Vortices moving in one layer induce stirring of passive scalars in the other layer. This is of interest since point vortices induce singular velocity fields in the layer they belong to; however, in the other layer, they induce regular velocity fields that generally result in a change in passive particle stirring. If the vortices are located at stagnation points, there are three different types of the fluid flow. We examine how properties of each flow configuration are modified if the vortices are displaced from the stagnation points and thus circulate in the immediate vicinity of these points. To that end, an analysis of the steady-state configurations is presented with an emphasis on the frequencies of fluid particle oscillations about the elliptic stagnation points. Asymptotic relations for the vortex and fluid particle zero-oscillation frequencies are derived in the vicinity of the corresponding elliptic points. By comparing the frequencies of fluid particles with the ones of the vortices, relations between the parameters that lead to enhanced stirring of fluid particles are established. It is also demonstrated that, if the central critical point is elliptic, then the fluid particle trajectories in its immediate vicinity are mostly stable making it harder for the vortex perturbation to induce stirring. Change in the type of the central point to a hyperbolic one enhances drastically the size of the chaotic dynamics region. Conditions on the type of the central critical point also ensue from the derived asymptotic relations.

Temporal Analysis and Automatic Calibration of the Velodyne HDL-32E LiDAR System

NASA Astrophysics Data System (ADS)

Chan, T. O.; Lichti, D. D.; Belton, D.

2013-10-01

At the end of the first quarter of 2012, more than 600 Velodyne LiDAR systems had been sold worldwide for various robotic and high-accuracy survey applications. The ultra-compact Velodyne HDL-32E LiDAR has become a predominant sensor for many applications that require lower sensor size/weight and cost. For high accuracy applications, cost-effective calibration methods with minimal manual intervention are always desired by users. However, the calibrations are complicated by the Velodyne LiDAR's narrow vertical field of view and the very highly time-variant nature of its measurements. In the paper, the temporal stability of the HDL-32E is first analysed as the motivation for developing a new, automated calibration method. This is followed by a detailed description of the calibration method that is driven by a novel segmentation method for extracting vertical cylindrical features from the Velodyne point clouds. The proposed segmentation method utilizes the Velodyne point cloud's slice-like nature and first decomposes the point clouds into 2D layers. Then the layers are treated as 2D images and are processed with the Generalized Hough Transform which extracts the points distributed in circular patterns from the point cloud layers. Subsequently, the vertical cylindrical features can be readily extracted from the whole point clouds based on the previously extracted points. The points are passed to the calibration that estimates the cylinder parameters and the LiDAR's additional parameters simultaneously by constraining the segmented points to fit to the cylindrical geometric model in such a way the weighted sum of the adjustment residuals are minimized. The proposed calibration is highly automatic and this allows end users to obtain the time-variant additional parameters instantly and frequently whenever there are vertical cylindrical features presenting in scenes. The methods were verified with two different real datasets, and the results suggest that up to 78.43% accuracy improvement for the HDL-32E can be achieved using the proposed calibration method.

Towards an acoustic model-based poroelastic imaging method: II. experimental investigation.

PubMed

Berry, Gearóid P; Bamber, Jeffrey C; Miller, Naomi R; Barbone, Paul E; Bush, Nigel L; Armstrong, Cecil G

2006-12-01

Soft biological tissue contains mobile fluid. The volume fraction of this fluid and the ease with which it may be displaced through the tissue could be of diagnostic significance and may also have consequences for the validity with which strain images can be interpreted according to the traditional idealizations of elastography. In a previous paper, under the assumption of frictionless boundary conditions, the spatio-temporal behavior of the strain field inside a compressed cylindrical poroelastic sample was predicted (Berry et al. 2006). In this current paper, experimental evidence is provided to confirm these predictions. Finite element modeling was first used to extend the previous predictions to allow for the existence of contact friction between the sample and the compressor plates. Elastographic techniques were then applied to image the time-evolution of the strain inside cylindrical samples of tofu (a suitable poroelastic material) during sustained unconfined compression. The observed experimental strain behavior was found to be consistent with the theoretical predictions. In particular, every sample studied confirmed that reduced values of radial strain advance with time from the curved cylindrical surface inwards towards the axis of symmetry. Furthermore, by fitting the predictions of an analytical model to a time sequence of strain images, parametric images of two quantities, each related to one or more of three poroelastic material constants were produced. The two parametric images depicted the Poisson's ratio (nu(s)) of the solid matrix and the product of the aggregate modulus (H(A)) of the solid matrix with the permeability (k) of the solid matrix to the pore fluid. The means of the pixel values in these images, nu(s) = 0.088 (standard deviation 0.023) and H(A)k = 1.449 (standard deviation 0.269) x 10(-7) m(2) s(-1), were in agreement with values derived from previously published data for tofu (Righetti et al. 2005). The results provide the first experimental detection of the fluid-flow-induced characteristic diffusion-like behavior of the strain in a compressed poroelastic material and allow parameters related to the above material constants to be determined. We conclude that it may eventually be possible to use strain data to detect and measure characteristics of diffusely distributed mobile fluid in tissue spaces that are too small to be imaged directly.

First-principles calculations of CdS-based nanolayers and nanotubes

NASA Astrophysics Data System (ADS)

Bandura, A. V.; Kuruch, D. D.; Evarestov, R. A.

2018-05-01

The first-principles simulations using hybrid exchange-correlation density functional and localized atomic basis set were performed to investigate the properties of CdS nanolayers and nanotubes constructed from wurtzite and zinc blende phases. Different types of cylindrical and facetted nanotubes have been considered. The new classification of the facetted nanotubes is proposed. The stability of CdS nanotubes has been analyzed using formation and strain energies. Obtained results show that facetted tubes are favorable as compared to the most of cylindrical ones. Nevertheless, the cylindrical nanotubes generated from the layers with experimentally proved freestanding existence, also have a chance to be synthesized. Preliminary calculation of facetted nanotubes constructed from the zinc blende phase gives evidence for their possible using in the photocatalytic decomposition of water.

Experimental investigation of convective stability in a superposed fluid and porous layer when heated from below

NASA Technical Reports Server (NTRS)

Chen, Falin; Chen, C. F.

1989-01-01

Experiments have been carried out in a horizontal superposed fluid and porous layer contained in a test box 24 cm x 12 cm x 4 cm high. The porous layer consisted of 3 mm diameter glass beads, and the fluids used were water, 60 and 90 percent glycerin-water solutions, and 100 percent glycerin. The depth ratio d, which is the ratio of the thickness of the fluid layer to that of the porous layer, varied from 0 to 1.0. Fluids of increasingly higher viscosity were used for cases with larger d in order to keep the temperature difference across the tank within reasonable limits. The size of the convection cells was inferred from temperature measurements made with embedded thermocouples and from temperature distributions at the top of the layer by use of liquid crystal film. The experimental results showed: (1) a precipitous decrease in the critical Rayleigh number as the depth of the fluid layer was increased from zero, and (2) an eightfold decrease in the critical wavelength between d = 0.1 and 0.2. Both of these results were predicted by the linear stability theory reported earlier (Chen and Chen, 1988).

Circularly-Polarized Microstrip Antenna

NASA Technical Reports Server (NTRS)

Stanton, P. H.

1985-01-01

Microstrip construction compact for mobile applications. Circularly polarized microstrip antenna made of concentric cylindrical layers of conductive and dielectric materials. Coaxial cable feedlines connected to horizontal and vertical subelements from inside. Vertical subelement acts as ground for horizontal subelement.

Aeroelastic analysis of circular cylindrical and truncated conical shells subjected to a supersonic flow

NASA Astrophysics Data System (ADS)

Sabri, Farhad

Shells of revolution, particularly cylindrical and conical shells, are one of the basic structural elements in the aerospace structures. With the advent of high speed aircrafts, these shells can show dynamic instabilities when they are exposed to a supersonic flow. Therefore, aeroelastic analysis of these elements is one of the primary design criteria which aeronautical engineers are dealing with. This analysis can be done with the help of finite element method (FEM) coupled with the computational fluid dynamic (CFD) or by experimental methods but it is time consuming and very expensive. The purpose of this dissertation is to develop such a numerical tool to do aeroelastic analysis in a fast and precise way. Meanwhile during the design stage, where the different configurations, loading and boundary conditions may need to be analyzed, this numerical method can be used very easily with the high order of reliability. In this study structural modeling is a combination of linear Sanders thin shell theory and classical finite element method. Based on this hybrid finite element method, the shell displacements are found from the exact solutions of shell theory rather than approximating by polynomial function done in traditional finite element method. This leads to a precise and fast convergence. Supersonic aerodynamic modeling is done based on the piston theory and modified piston theory with the shell curvature term. The stress stiffening due to lateral pressure and axial compression are also taken into accounts. Fluid-structure interaction in the presence of inside quiescent fluid is modeled based on the potential theory. In this method, fluid is considered as a velocity potential variable at each node of the shell element where its motion is expressed in terms of nodal elastic displacements at the fluid-structure interface. This proposed hybrid finite element has capabilities to do following analysis: (i) Buckling and vibration of an empty or partially fluid filled circular cylindrical shell or truncated conical shell subjected to internal/external pressure and axial compression loading. This is a typical example of external liquid propellant tanks of space shuttles and re-entry vehicles where they may experience this kind of loading during the flight. In the current work, different end boundary conditions of a circular cylindrical shell with different filling ratios were analyzed. To the best author' knowledge this is the first study where this kind of complex loading and boundary conditions are treated together during such an analysis. Only static instability, divergence, was observed where it showed that the fluid filling ratio does not have any effect on the critical buckling pressure and axial compression. It only reduces the vibration frequencies. It also revealed that the pressurized shell loses its stability at a higher critical axial load. (ii) Aeroelastic analysis of empty or partially liquid filled circular cylindrical and conical shells. Different boundary conditions with different geometries of shells subjected to supersonic air flow are studied here. In all of cases shell loses its stability though the coupled mode flutter. The results showed that internal pressure has a stabilizing effect and increases the critical flutter speed. It is seen that the value of critical dynamic pressure changes rapidly and widely as the filling ratio increases from a low value. In addition, by increasing the length ratio the decrement of flutter speed is decreased and vanishes. This rapid change in critical dynamic pressure at low filling ratios and its almost steady behaviour at large filling ratios indicate that the fluid near the bottom of the shell is largely influenced by elastic deformation when a shell is subjected to external subsonic flow. Based on comparison with the existing numerical, analytical and experimental data and the power of capabilities of this hybrid finite element method to model different boundary conditions and complex loadings, this FEM package can be used effectively for the design of advanced aerospace structures. It provides the results at less computational cost compare to the commercial FEM software, which imposes some restrictions when such an analysis is done.

Financial Brownian Particle in the Layered Order-Book Fluid and Fluctuation-Dissipation Relations

NASA Astrophysics Data System (ADS)

Yura, Yoshihiro; Takayasu, Hideki; Sornette, Didier; Takayasu, Misako

2014-03-01

We introduce a novel description of the dynamics of the order book of financial markets as that of an effective colloidal Brownian particle embedded in fluid particles. The analysis of comprehensive market data enables us to identify all motions of the fluid particles. Correlations between the motions of the Brownian particle and its surrounding fluid particles reflect specific layering interactions; in the inner layer the correlation is strong and with short memory, while in the outer layer it is weaker and with long memory. By interpreting and estimating the contribution from the outer layer as a drag resistance, we demonstrate the validity of the fluctuation-dissipation relation in this nonmaterial Brownian motion process.

Financial Brownian particle in the layered order-book fluid and fluctuation-dissipation relations.

PubMed

Yura, Yoshihiro; Takayasu, Hideki; Sornette, Didier; Takayasu, Misako

2014-03-07

We introduce a novel description of the dynamics of the order book of financial markets as that of an effective colloidal Brownian particle embedded in fluid particles. The analysis of comprehensive market data enables us to identify all motions of the fluid particles. Correlations between the motions of the Brownian particle and its surrounding fluid particles reflect specific layering interactions; in the inner layer the correlation is strong and with short memory, while in the outer layer it is weaker and with long memory. By interpreting and estimating the contribution from the outer layer as a drag resistance, we demonstrate the validity of the fluctuation-dissipation relation in this nonmaterial Brownian motion process.

Absorbent product to absorb fluids. [for collection of human wastes

NASA Technical Reports Server (NTRS)

Dawn, F. S.; Correale, J. V. (Inventor)

1982-01-01

A multi-layer absorbent product for use in contact with the skin to absorb fluids is discussed. The product utilizes a water pervious facing layer for contacting the skin, overlayed by a first fibrous wicking layer, the wicking layer preferably being of the one-way variety in which fluid or liquid is moved away from the facing layer. The product further includes a first container section defined by inner and outer layer of a water pervious wicking material between which is disposed a first absorbent mass. A second container section defined by inner and outer layers between which is disposed a second absorbent mass and a liquid impermeable/gas permeable layer. Spacesuit applications are discussed.

Extinction cross-section cancellation of a cylindrical radiating active source near a rigid corner and acoustic invisibility

NASA Astrophysics Data System (ADS)

Mitri, F. G.

2017-11-01

Active cloaking in its basic form requires that the extinction cross-section (or energy efficiency) from a radiating body vanishes. In this analysis, this physical effect is demonstrated for an active cylindrically radiating acoustic source in a non-viscous fluid, undergoing periodic axisymmetric harmonic vibrations near a rigid corner (i.e., quarter-space). The rigorous multipole expansion method in cylindrical coordinates, the method of images, and the addition theorem of cylindrical wave functions are used to derive closed-form mathematical expressions for the radiating, amplification, and extinction cross-sections of the active source. Numerical computations are performed assuming monopole and dipole modal oscillations of the circular source. The results reveal some of the situations where the extinction energy efficiency factor of the active source vanishes depending on its size and location with respect to the rigid corner, thus, achieving total invisibility. Moreover, the extinction energy efficiency factor varies between positive or negative values. These effects also occur for higher-order modal oscillations of the active source. The results find potential applications in the development of acoustic cloaking devices and invisibility in underwater acoustics or other areas.

Graphene-Based Electrode for a Supercapacitor

NASA Technical Reports Server (NTRS)

Chen, Bin (Inventor); Meyyappan, Meyya (Inventor)

2015-01-01

A supercapacitor electrode mechanism comprising an electrically conductive, porous substrate, having one or more metallic oxides deposited on a first surface and a chemically reduced graphene oxide deposited on a second surface, to thereby provide an electrical double layer associated with the substrate. The substrate may be carbon paper or a similar substance. The layers of the supercapacitor are optionally rolled into an approximately cylindrical structure.

Relation between boundary slip mechanisms and waterlike fluid behavior.

PubMed

Ternes, Patricia; Salcedo, Evy; Barbosa, Marcia C

2018-03-01

The slip of a fluid layer in contact with a solid confining surface is investigated for different temperatures and densities using molecular dynamic simulations. We show that for an anomalous waterlike fluid the slip goes as follows: for low levels of shear, defect slip appears and is related to the particle exchange between the fluid layers; at high levels of shear, global slip occurs and is related to the homogeneous distribution of the fluid in the confining surfaces. The oscillations in the transition velocity from defect to global slip are shown to be associated with changes in the layering distribution in the anomalous fluid.

Bio-oil production from biomass via supercritical fluid extraction

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

Durak, Halil, E-mail: halildurak@yyu.edu.tr

2016-04-18

Supercritical fluid extraction is used for producing bio-fuel from biomass. Supercritical fluid extraction process under supercritical conditions is the thermally disruption process of the lignocellulose or other organic materials at 250-400 °C temperature range under high pressure (4-5 MPa). Supercritical fluid extraction trials were performed in a cylindrical reactor (75 mL) in organic solvents (acetone, ethanol) under supercritical conditions with (calcium hydroxide, sodium carbonate) and without catalyst at the temperatures of 250, 275 and 300 °C. The produced liquids at 300 °C in supercritical liquefaction were analyzed and characterized by elemental, GC-MS and FT-IR. 36 and 37 different types of compounds weremore » identified by GC-MS obtained in acetone and ethanol respectively.« less

Fluid-structure interaction in fast breeder reactors

NASA Astrophysics Data System (ADS)

Mitra, A. A.; Manik, D. N.; Chellapandi, P. A.

2004-05-01

A finite element model for the seismic analysis of a scaled down model of Fast breeder reactor (FBR) main vessel is proposed to be established. The reactor vessel, which is a large shell structure with a relatively thin wall, contains a large volume of sodium coolant. Therefore, the fluid structure interaction effects must be taken into account in the seismic design. As part of studying fluid-structure interaction, the fundamental frequency of vibration of a circular cylindrical shell partially filled with a liquid has been estimated using Rayleigh's method. The bulging and sloshing frequencies of the first four modes of the aforementioned system have been estimated using the Rayleigh-Ritz method. The finite element formulation of the axisymmetric fluid element with Fourier option (required due to seismic loading) is also presented.

Artificial heart for humanoid robot using coiled SMA actuators

NASA Astrophysics Data System (ADS)

Potnuru, Akshay; Tadesse, Yonas

2015-03-01

Previously, we have presented the design and characterization of artificial heart using cylindrical shape memory alloy (SMA) actuators for humanoids [1]. The robotic heart was primarily designed to pump a blood-like fluid to parts of the robot such as the face to simulate blushing or anger by the use of elastomeric substrates for the transport of fluids. It can also be used for other applications. In this paper, we present an improved design by using high strain coiled SMAs and a novel pumping mechanism that uses sequential actuation to create peristalsis-like motions, and hence pump the fluid. Various placements of actuators will be investigated with respect to the silicone elastomeric body. This new approach provides a better performance in terms of the fluid volume pumped.

Stability of anisotropic self-gravitating fluids

NASA Astrophysics Data System (ADS)

Ahmad, S.; Jami, A. Rehman; Mughal, M. Z.

2018-06-01

The aim of this paper is to study the stability as well as the existence of self-gravitating anisotropic fluids in Λ-dominated era. Taking a cylindrically symmetric and static spacetime, we computed the corresponding equations of motion in the background of anisotropic fluid distributions. The realistic formulation of energy momentum tensor as well as theoretical model of the scale factors are considered in order to describe some physical properties of the anisotropic fluids. To find the stability of the compact star, we have used Herrera’s technique which is based on finding the radial and the transverse components of the speed of sound. Moreover, the behaviors of other physical quantities are also discussed like anisotropy, matching conditions of interior metric and exterior metric and compactness of the compact structures are also discussed.

Instability of fluid flow over saturated porous medium

NASA Astrophysics Data System (ADS)

Lyubimova, Tatyana; Kolchanova, Ekaterina; Lyubimov, Dmitry

2013-04-01

We investigate the stability of a fluid flow over a saturated porous medium. The problem is of importance due to the applications to washing out of contaminants from the bottom layer of vegetation, whose properties are similar to the properties of porous medium. In the case of porous medium with the relatively high permeability and porosity the flow involves a part of the fluid saturating the porous medium, with the tangential fluid velocity drop occurring because of the resistance of the solid matrix. The drop leads to the instability analogous to Kelvin-Helmholtz one accompanied by the formation of travelling waves. In the present paper we consider a two-layer system consisting of a pure fluid layer and a porous layer saturated by the fluid located underneath. The system is bounded by a rigid surface at the bottom and a non-deformable free surface at the top. It is under the gravity and inclined at a slight angle to the horizontal axis. The boundary conditions at the interface between the fluid and porous layers are the continuity of fluid velocities and the balance of normal and tangential stresses taking into account the resistance of the solid matrix with respect to the fluid flow near the interface [1-2]. The problem is solved in the framework of the Brinkman model applying the classical shooting algorithm with orthogonalization. The stability boundaries of the stationary fluid flow over the saturated porous medium with respect to the small oscillatory perturbations are obtained for the various values of the Darcy number and the ratio of the porous layer thickness to the full thickness of the system d. It was shown that at the d > 0.5 with increasing the porous layer thickness (or with decreasing of the fluid layer thickness) the stability threshold rises. This is because of the fact that the instability is primarily caused by perturbations located in the fluid layer. At the d < 0.5 the reduction of the porous layer thickness leads to the stability threshold growth. The numerical calculations were also conducted for nonlinear regimes of the flow applying the finite-element method. Flow characteristics are determined at supercritical values of parameters. The work was made under the financial support of Russian Foundation for Basic Research (Grant 12-01-00795). 1. Ochoa-Tapia J. A. and Whitaker S. Momentum transfer at the boundary between a porous medium and a homogeneous fluid-I. Theoretical development. Int. J. Heat Mass Transfer. 1995. N 38. P. 2635-2646. 2. Ochoa-Tapia J. A. and Whitaker S. Momentum transfer at the boundary between a porous medium and a homogeneous fluid-II. Comparison with experiment. Int. J. Heat Mass Transfer. 1995. N 38. P. 2647-2655.

Imploding spherical and cylindrical shocks

NASA Astrophysics Data System (ADS)

Yousaf, M.

1986-03-01

In this paper it is shown that the value of the similarity exponent α derived analytically by Fujimoto and Mishkin [J. Fluid Mech. 89, 61 (1978); Phys. Fluids 21, 1933 (1978)] is exactly the same as that found by Stanyukovich [Unsteady Motion of Continuous Media, (Academic, New York, 1960)]. Since the result found by Stanyukovich is an approximation to α, Fujimoto and Mishkin's claim to have an exact expression of α is false. The two methods are outlined and Stanyukovich's result is simplified to show its equivalence to the work of Fujimoto and Mishkin.

Comparison of Computational Results with a Low-g, Nitrogen Slosh and Boiling Experiment

NASA Technical Reports Server (NTRS)

Stewart, Mark; Moder, Jeff

2015-01-01

The proposed paper will compare a fluid/thermal simulation, in FLUENT, with a low-g, nitrogen slosh experiment. The French Space Agency, CNES, performed cryogenic nitrogen experiments in several zero gravity aircraft campaigns. The computational results have been compared with high-speed photographic data, pressure data, and temperature data from sensors on the axis of the cylindrically shaped tank. The comparison between these experimental and computational results is generally favorable: the initial temperature stratification is in good agreement, and the two-phase fluid motion is qualitatively captured.

Energy loss from a moving vortex in superfluid helium

NASA Astrophysics Data System (ADS)

Zieve, R. J.; Frei, C. M.; Wolfson, D. L.

2012-11-01

We present measurements on both energy loss and pinning for a vortex terminating on the curved surface of a cylindrical container. We vary surface roughness, cell diameter, fluid velocity, and temperature. Although energy loss and pinning both arise from interactions between the vortex and the surface, their dependences on the experimental parameters differ, suggesting that different mechanisms govern the two effects. We propose that the energy loss stems from reconnections with a mesh of microscopic vortices that covers the cell wall, while pinning is dominated by other influences such as the local fluid velocity.

Optical elements formed by compressed gases: Analysis and potential applications

NASA Technical Reports Server (NTRS)

Howes, W. L.

1986-01-01

Spherical, cylindrical, and conical shock waves are optically analogous to gas lenses. The geometrical optics of these shock configurations are analyzed as they pertain to flow visualization instruments, particularly the rainbow schlieren apparatus and single-pass interferometers. It is proposed that a lens or mirror formed by gas compressed between plastic sheets has potential as a fluid visualization test object; as the objective mirror in a very large space-based telescope, communication antenna, or energy collector; as the objective mirror in inexpensive commercial telescopes; and as a component in fluid visualization apparatuses.

Deformation of the free surface of a conducting fluid in the magnetic field of current-carrying linear conductors

NASA Astrophysics Data System (ADS)

Zubarev, N. M.; Zubareva, O. V.

2017-06-01

The magnetic shaping problem is studied for the situation where a cylindrical column of a perfectly conducting fluid is deformed by the magnetic field of a system of linear current-carrying conductors. Equilibrium is achieved due to the balance of capillary and magnetic pressures. Two two-parametric families of exact solutions of the problem are obtained with the help of conformal mapping technique. In accordance with them, the column essentially deforms in the cross section up to its disintegration.

Time-dependent patterns in quasivertical cylindrical binary convection.

PubMed

Alonso, Arantxa; Mercader, Isabel; Batiste, Oriol

2018-02-01

This paper reports on numerical investigations of the effect of a slight inclination α on pattern formation in a shallow vertical cylindrical cell heated from below for binary mixtures with a positive value of the Soret coefficient. By using direct numerical simulation of the three-dimensional Boussinesq equations with Soret effect in cylindrical geometry, we show that a slight inclination of the cell in the range α≈0.036rad=2^{∘} strongly influences pattern selection. The large-scale shear flow (LSSF) induced by the small tilt of gravity overcomes the squarelike arrangements observed in noninclined cylinders in the Soret regime, stratifies the fluid along the direction of inclination, and produces an enhanced separation of the two components of the mixture. The competition between shear effects and horizontal and vertical buoyancy alters significantly the dynamics observed in noninclined convection. Additional unexpected time-dependent patterns coexist with the basic LSSF. We focus on an unsual periodic state recently discovered in an experiment, the so-called superhighway convection state (SHC), in which ascending and descending regions of fluid move in opposite directions. We provide numerical confirmation that Boussinesq Navier-Stokes equations with standard boundary conditions contain the essential ingredients that allow for the existence of such a state. Also, we obtain a persistent heteroclinic structure where regular oscillations between a SHC pattern and a state of nearly stationary longitudinal rolls take place. We characterize numerically these time-dependent patterns and investigate the dynamics around the threshold of convection.

Time-dependent patterns in quasivertical cylindrical binary convection

NASA Astrophysics Data System (ADS)

Alonso, Arantxa; Mercader, Isabel; Batiste, Oriol

2018-02-01

This paper reports on numerical investigations of the effect of a slight inclination α on pattern formation in a shallow vertical cylindrical cell heated from below for binary mixtures with a positive value of the Soret coefficient. By using direct numerical simulation of the three-dimensional Boussinesq equations with Soret effect in cylindrical geometry, we show that a slight inclination of the cell in the range α ≈0.036 rad =2∘ strongly influences pattern selection. The large-scale shear flow (LSSF) induced by the small tilt of gravity overcomes the squarelike arrangements observed in noninclined cylinders in the Soret regime, stratifies the fluid along the direction of inclination, and produces an enhanced separation of the two components of the mixture. The competition between shear effects and horizontal and vertical buoyancy alters significantly the dynamics observed in noninclined convection. Additional unexpected time-dependent patterns coexist with the basic LSSF. We focus on an unsual periodic state recently discovered in an experiment, the so-called superhighway convection state (SHC), in which ascending and descending regions of fluid move in opposite directions. We provide numerical confirmation that Boussinesq Navier-Stokes equations with standard boundary conditions contain the essential ingredients that allow for the existence of such a state. Also, we obtain a persistent heteroclinic structure where regular oscillations between a SHC pattern and a state of nearly stationary longitudinal rolls take place. We characterize numerically these time-dependent patterns and investigate the dynamics around the threshold of convection.

Oxazine-based sensor for contaminant detection, fabrication method therefor, and uses thereof

DOEpatents

Nnanna, Agbai Agwu; Jalal, Ahmed Hasnian

2014-05-27

A sensor, a method for its fabrication, and a method for its use to detect contaminants, for example, ammonia, in stagnant and dynamic fluid media, especially liquid media. The sensor is an opto-chemical sensor that includes a polymer optical fiber, a sensing layer comprising oxazine 170 perchlorate on the polymer optical fiber, and a membrane layer on the sensing layer. The membrane layer is gas permeable and not permeable to the fluid in the fluid system, and moisture is entrapped by and between the sensing and membrane layers.

Shear-enhanced compaction in viscoplastic rocks

NASA Astrophysics Data System (ADS)

Yarushina, V. M.; Podladchikov, Y. Y.

2012-04-01

The phenomenon of mutual influence of compaction and shear deformation was repeatedly reported in the literature over the past years. Dilatancy and shear-enhanced compaction of porous rocks were experimentally observed during both rate-independent and rate-dependent inelastic deformation. Plastic pore collapse was preceding the onset of dilatancy and shear-enhanced compaction. Effective bulk viscosity is commonly used to describe compaction driven fluid flow in porous rocks. Experimental data suggest that bulk viscosity of a fluid saturated rock might be a function of both the effective pressure and the shear stress. Dilatancy and shear-enhanced compaction can alter the transport properties of rocks through their influence on permeability and compaction length scale. Recent investigations show that shear stresses in deep mantle rocks can be responsible for spontaneous development of localized melt-rich bands and segregation of small amounts of melt from the solid rock matrix through shear channeling instability. Usually it is assumed that effective viscosity is a function of porosity only. Thus coupling between compaction and shear deformation is ignored. Spherical model which considers a hollow sphere subjected to homogeneous tractions on the outer boundary as a representative elementary volume succeeded in predicting the volumetric compaction behavior of porous rocks and metals to a hydrostatic pressure in a wide range of porosities. Following the success of this simple model we propose a cylindrical model of void compaction and decompaction due to the non-hydrostatic load. The infinite viscoplastic layer with a cylindrical hole is considered as a representative volume element. The remote boundary of the volume is subjected to a homogeneous non-hydrostatic load such that plane strain conditions are fulfilled through the volume. At some critical values of remote stresses plastic zone develops around the hole. The dependence of the effective bulk viscosity on the properties of individual components as well as on the stress state is examined. We show that bulk viscosity is a function of porosity, effective pressure and shear stress. Decreasing porosity tends to increase bulk viscosity whereas increasing shear stress and increasing effective pressure reduce it.

Numerical heat transfer study in a scattering, absorbing and emitting semi-transparent porous medium in a cylindrical enclosure

NASA Astrophysics Data System (ADS)

Timoumi, M.; Chérif, B.; Sifaoui, M. S.

2005-12-01

In this paper, heat transfer problem through a semi-transparent porous medium in a cylindrical enclosure is investigated. The governing equations for this problem and the boundary conditions are non-linear differential equations depending on the dimensionless radial coordinate, Planck number N, scattering albedo ω, walls emissivity and thermal conductivity ratio kr. The set of differential equations are solved by a numerical technique taken from the IMSL MATH/LIBRARY. Various results are obtained for the dimensionless temperature profiles in the solid and fluid phases and the radiative heat flux. The effects of some radiative properties of the medium on the heat transfer rate are examined.

Water Jets from Bottles, Buckets, Barrels, and Vases with Holes

NASA Astrophysics Data System (ADS)

Lopac, Vjera

2015-03-01

Observation of the water jets flowing from three equidistant holes on the side of a vertical cylindrical bottle is an interesting and widely used didactical experiment illustrating the laws of fluids in motion. In this paper we analyze theoretically and numerically the ranges of the stationary water jets flowing from various rotationally symmetric vessels with holes, and their dependence on the height of the holes above the bottom, on thickness of the block supporting the vessel, and on different shapes of the vessel profile. This investigation was motivated by controversial descriptions and illustrations repeatedly found in physics textbooks and by the fact that previously in the physics teaching literature only the cylindrical vessel was treated.

Nonlinear saturation of the Rayleigh instability due to oscillatory flow in a liquid-lined tube

NASA Astrophysics Data System (ADS)

Halpern, David; Grotberg, James B.

2003-10-01

In this paper, the stability of core annular flows consisting of two immiscible fluids in a cylindrical tube with circular cross-section is examined. Such flows are important in a wide range of industrial and biomedical applications. For example, in secondary oil recovery, water is pumped into the well to displace the remaining oil. It is also of relevance in the lung, where a thin liquid film coats the inner surface of the small airways of the lungs. In both cases, the flow is influenced by a surface-tension instability, which may induce the breakup of the core fluid into short plugs, reducing the efficiency of the oil recovery, or blocking the passage of air in the lung thus inducing airway closure. We consider the stability of a thin film coating the inner surface of a rigid cylindrical tube with the less viscous fluid in the core. For thick enough films, the Rayleigh instability forms a liquid bulge that can grow to eventually create a plug blocking the tube. The analysis explores the effect of an oscillatory core flow on the interfacial dynamics and particularly the nonlinear stabilization of the bulge. The oscillatory core flow exerts tangential and normal stresses on the interface between the two fluids that are simplified by uncoupling the core and film analyses in the thin-film high-frequency limit of the governing equations. Lubrication theory is used to derive a nonlinear evolution equation for the position of the air liquid interface which includes the effects of the core flow. It is shown that the core flow can prevent plug formation of the more viscous film layer by nonlinear saturation of the capillary instability. The stabilization mechanism is similar to that of a reversing butter knife, where the core shear wipes the growing liquid bulge back on to the tube wall during the main tidal volume stroke, but allows it to grow back as the stoke and shear turn around. To be successful, the leading film thickness ahead of the bulge must be smaller than the trailing film thickness behind it, a requirement necessitating a large enough core capillary number which promotes a large core shear stress on the interface. The core capillary number is defined to be the ratio of core viscous forces to surface tension forces. When this process is tuned correctly, the two phases balance and there is no net growth of the liquid bulge over one cycle. We find that there is a critical frequency above which plug formation does not occur, and that this critical frequency increases as the tidal volume amplitude of the core flow decreases.

Pericarditis

MedlinePlus

... properly. The sac is made of two thin layers of tissue that enclose your heart. Between the two layers is a small amount of fluid. This fluid keeps the layers from rubbing against each other and causing friction. ...

Wind Tunnel Interference on Wings, Bodies and Airscrews

DTIC Science & Technology

1933-09-13

jet usually issues from a eliminated by designing tie wiand tunnel with a slight expanson closed cylindrical mouth immediately in front of the model...pressilre at the boundary. This type of constraiA 16 \\1 h 3/. would occur under the ideal conditions of a perfect fluid, and it is I Eperimental confirmation

Water Jets from Bottles, Buckets, Barrels, and Vases with Holes

ERIC Educational Resources Information Center

Lopac, Vjera

2015-01-01

Observation of the water jets flowing from three equidistant holes on the side of a vertical cylindrical bottle is an interesting and widely used didactical experiment illustrating the laws of fluids in motion. In this paper we analyze theoretically and numerically the ranges of the stationary water jets flowing from various rotationally symmetric…

10 CFR Appendix D to Part 110 - Illustrative List of Aerodynamic Enrichment Plant Equipment and Components Under NRC Export...

Code of Federal Regulations, 2013 CFR

2013-01-01

... control the flow within the cascade: (1) Separation nozzles and assemblies. Especially designed or... fluids. (10) Special shut-off and control valves. Especially designed or prepared manual or automated... assemblies. Especially designed or prepared vortex tubes that are cylindrical or tapered, made of or...

10 CFR Appendix D to Part 110 - Illustrative List of Aerodynamic Enrichment Plant Equipment and Components Under NRC Export...

Code of Federal Regulations, 2014 CFR

2014-01-01

... control the flow within the cascade: (1) Separation nozzles and assemblies. Especially designed or... fluids. (10) Special shut-off and control valves. Especially designed or prepared manual or automated... assemblies. Especially designed or prepared vortex tubes that are cylindrical or tapered, made of or...

10 CFR Appendix D to Part 110 - Illustrative List of Aerodynamic Enrichment Plant Equipment and Components Under NRC Export...

Code of Federal Regulations, 2012 CFR

2012-01-01

... control the flow within the cascade: (1) Separation nozzles and assemblies. Especially designed or... fluids. (10) Special shut-off and control valves. Especially designed or prepared manual or automated... assemblies. Especially designed or prepared vortex tubes that are cylindrical or tapered, made of or...

A Multi Water Bag model of drift kinetic electron plasmaa

NASA Astrophysics Data System (ADS)

Morel, Pierre; Ghiro, Florent Dreydemy; Berionni, Vincent; Coulette, David; Besse, Nicolas; Gürcan, Özgür D.

2014-08-01

A Multi Water Bag model is proposed for describing drift kinetic plasmas in a magnetized cylindrical geometry, relevant for various experimental devices, solar wind modeling... The Multi Water Bag (MWB) model is adapted to the description of a plasma with kinetic electrons as well as an arbitrary number of kinetic ions. This allows to describe the kinetic dynamics of the electrons, making possible the study of electron temperature gradient (ETG) modes, in addition to the effects of non adiabatic electrons on the ion temperature gradient (ITG) modes, that are of prime importance in the magnetized plasmas micro-turbulence [X. Garbet, Y. Idomura, L. Villard, T.H. Watanabe, Nucl. Fusion 50, 043002 (2010); J.A. Krommes, Ann. Rev. Fluid Mech. 44, 175 (2012)]. The MWB model is shown to link kinetic and fluid descriptions, depending on the number of bags considered. Linear stability of the ETG modes is presented and compared to the existing results regarding cylindrical ITG modes [P. Morel, E. Gravier, N. Besse, R. Klein, A. Ghizzo, P. Bertrand, W. Garbet, Ph. Ghendrih, V. Grandgirard, Y. Sarazin, Phys. Plasmas 14, 112109 (2007)].

Shearfree cylindrical gravitational collapse

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

Di Prisco, A.; Herrera, L.; MacCallum, M. A. H.

2009-09-15

We consider diagonal cylindrically symmetric metrics, with an interior representing a general nonrotating fluid with anisotropic pressures. An exterior vacuum Einstein-Rosen spacetime is matched to this using Darmois matching conditions. We show that the matching conditions can be explicitly solved for the boundary values of metric components and their derivatives, either for the interior or exterior. Specializing to shearfree interiors, a static exterior can only be matched to a static interior, and the evolution in the nonstatic case is found to be given in general by an elliptic function of time. For a collapsing shearfree isotropic fluid, only a Robertson-Walkermore » dust interior is possible, and we show that all such cases were included in Cocke's discussion. For these metrics, Nolan and Nolan have shown that the matching breaks down before collapse is complete, and Tod and Mena have shown that the spacetime is not asymptotically flat in the sense of Berger, Chrusciel, and Moncrief. The issues about energy that then arise are revisited, and it is shown that the exterior is not in an intrinsic gravitational or superenergy radiative state at the boundary.« less

Acoustic streaming, fluid mixing, and particle transport by a Gaussian ultrasound beam in a cylindrical container

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

Marshall, Jeffrey S., E-mail: jeffm@cems.uvm.edu; Wu, Junru

A computational study is reported of the acoustic streaming flow field generated by a Gaussian ultrasound beam propagating normally toward the end wall of a cylindrical container. Particular focus is given to examining the effectiveness of the acoustic streaming flow for fluid mixing within the container, for deposition of particles in suspension onto the bottom surface, and for particle suspension from the bottom surface back into the flow field. The flow field is assumed to be axisymmetric with the ultrasound transducer oriented parallel to the cylinder axis and normal to the bottom surface of the container, which we refer tomore » as the impingement surface. Reflection of the sound from the impingement surface and sound absorption within the material at the container bottom are both accounted for in the computation. The computation also accounts for thermal buoyancy force due to ultrasonic heating of the impingement surface, but over the time period considered in the current simulations, the flow is found to be dominated by the acoustic streaming force, with only moderate effect of buoyancy force.« less

Acoustic streaming, fluid mixing, and particle transport by a Gaussian ultrasound beam in a cylindrical container

NASA Astrophysics Data System (ADS)

Marshall, Jeffrey S.; Wu, Junru

2015-10-01

A computational study is reported of the acoustic streaming flow field generated by a Gaussian ultrasound beam propagating normally toward the end wall of a cylindrical container. Particular focus is given to examining the effectiveness of the acoustic streaming flow for fluid mixing within the container, for deposition of particles in suspension onto the bottom surface, and for particle suspension from the bottom surface back into the flow field. The flow field is assumed to be axisymmetric with the ultrasound transducer oriented parallel to the cylinder axis and normal to the bottom surface of the container, which we refer to as the impingement surface. Reflection of the sound from the impingement surface and sound absorption within the material at the container bottom are both accounted for in the computation. The computation also accounts for thermal buoyancy force due to ultrasonic heating of the impingement surface, but over the time period considered in the current simulations, the flow is found to be dominated by the acoustic streaming force, with only moderate effect of buoyancy force.

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

NASA Astrophysics Data System (ADS)

Wang, Gerald J.; Hadjiconstantinou, Nicolas G.

2017-09-01

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

Synchrotron X-ray measurement techniques for thermal barrier coated cylindrical samples under thermal gradients.

PubMed

Siddiqui, Sanna F; Knipe, Kevin; Manero, Albert; Meid, Carla; Wischek, Janine; Okasinski, John; Almer, Jonathan; Karlsson, Anette M; Bartsch, Marion; Raghavan, Seetha

2013-08-01

Measurement techniques to obtain accurate in situ synchrotron strain measurements of thermal barrier coating systems (TBCs) applied to hollow cylindrical specimens are presented in this work. The Electron Beam Physical Vapor Deposition coated specimens with internal cooling were designed to achieve realistic temperature gradients over the TBC coated material such as that occurring in the turbine blades of aeroengines. Effects of the circular cross section on the x-ray diffraction (XRD) measurements in the various layers, including the thermally grown oxide, are investigated using high-energy synchrotron x-rays. Multiple approaches for beam penetration including collection, tangential, and normal to the layers, along with variations in collection parameters are compared for their ability to attain high-resolution XRD data from the internal layers. This study displays the ability to monitor in situ, the response of the internal layers within the TBC, while implementing a thermal gradient across the thickness of the coated sample. The thermal setup maintained coating surface temperatures in the range of operating conditions, while monitoring the substrate cooling, for a controlled thermal gradient. Through variation in measurement location and beam parameters, sufficient intensities are obtained from the internal layers which can be used for depth resolved strain measurements. Results are used to establish the various techniques for obtaining XRD measurements through multi-layered coating systems and their outcomes will pave the way towards goals in achieving realistic in situ testing of these coatings.

Synchrotron X-ray measurement techniques for thermal barrier coated cylindrical samples under thermal gradients

NASA Astrophysics Data System (ADS)

Siddiqui, Sanna F.; Knipe, Kevin; Manero, Albert; Meid, Carla; Wischek, Janine; Okasinski, John; Almer, Jonathan; Karlsson, Anette M.; Bartsch, Marion; Raghavan, Seetha

2013-08-01

Measurement techniques to obtain accurate in situ synchrotron strain measurements of thermal barrier coating systems (TBCs) applied to hollow cylindrical specimens are presented in this work. The Electron Beam Physical Vapor Deposition coated specimens with internal cooling were designed to achieve realistic temperature gradients over the TBC coated material such as that occurring in the turbine blades of aeroengines. Effects of the circular cross section on the x-ray diffraction (XRD) measurements in the various layers, including the thermally grown oxide, are investigated using high-energy synchrotron x-rays. Multiple approaches for beam penetration including collection, tangential, and normal to the layers, along with variations in collection parameters are compared for their ability to attain high-resolution XRD data from the internal layers. This study displays the ability to monitor in situ, the response of the internal layers within the TBC, while implementing a thermal gradient across the thickness of the coated sample. The thermal setup maintained coating surface temperatures in the range of operating conditions, while monitoring the substrate cooling, for a controlled thermal gradient. Through variation in measurement location and beam parameters, sufficient intensities are obtained from the internal layers which can be used for depth resolved strain measurements. Results are used to establish the various techniques for obtaining XRD measurements through multi-layered coating systems and their outcomes will pave the way towards goals in achieving realistic in situ testing of these coatings.

International Congress of Fluid Mechanics, 3rd, Cairo, Egypt, Jan. 2-4, 1990, Proceedings. Volumes 1, 2, 3, & 4

NASA Astrophysics Data System (ADS)

Nayfeh, A. H.; Mobarak, A.; Rayan, M. Abou

This conference presents papers in the fields of flow separation, unsteady aerodynamics, fluid machinery, boundary-layer control and stability, grid generation, vorticity dominated flows, and turbomachinery. Also considered are propulsion, waves and sound, rotor aerodynamics, computational fluid dynamics, Euler and Navier-Stokes equations, cavitation, mixing and shear layers, mixing layers and turbulent flows, and fluid machinery and two-phase flows. Also addressed are supersonic and reacting flows, turbulent flows, and thermofluids.

Complex large-scale convection of a viscous incompressible fluid with heat exchange according to Newton's law

NASA Astrophysics Data System (ADS)

Gorshkov, A. V.; Prosviryakov, E. Yu.

2017-12-01

The paper considers the construction of analytical solutions to the Oberbeck-Boussinesq system. This system describes layered Bénard-Marangoni convective flows of an incompressible viscous fluid. The third-kind boundary condition, i. e. Newton's heat transfer law, is used on the boundaries of a fluid layer. The obtained solution is analyzed. It is demonstrated that there is a fluid layer thickness with tangential stresses vanishing simultaneously, this being equivalent to the existence of tensile and compressive stresses.

Particle-bearing currents in uniform density and two-layer fluids

NASA Astrophysics Data System (ADS)

Sutherland, Bruce R.; Gingras, Murray K.; Knudson, Calla; Steverango, Luke; Surma, Christopher

2018-02-01

Lock-release gravity current experiments are performed to examine the evolution of a particle bearing flow that propagates either in a uniform-density fluid or in a two-layer fluid. In all cases, the current is composed of fresh water plus micrometer-scale particles, the ambient fluid is saline, and the current advances initially either over the surface as a hypopycnal current or at the interface of the two-layer fluid as a mesopycnal current. In most cases the tank is tilted so that the ambient fluid becomes deeper with distance from the lock. For hypopycnal currents advancing in a uniform density fluid, the current typically slows as particles rain out of the current. While the loss of particles alone from the current should increase the current's buoyancy and speed, in practice the current's speed decreases because the particles carry with them interstitial fluid from the current. Meanwhile, rather than settling on the sloping bottom of the tank, the particles form a hyperpycnal (turbidity) current that advances until enough particles rain out that the relatively less dense interstitial fluid returns to the surface, carrying some particles back upward. When a hypopycnal current runs over the surface of a two-layer fluid, the particles that rain out temporarily halt their descent as they reach the interface, eventually passing through it and again forming a hyperpycnal current. Dramatically, a mesopycnal current in a two-layer fluid first advances along the interface and then reverses direction as particles rain out below and fresh interstitial fluid rises above.

Seismic behavior of a low-rise horizontal cylindrical tank

NASA Astrophysics Data System (ADS)

Fiore, Alessandra; Rago, Carlo; Vanzi, Ivo; Greco, Rita; Briseghella, Bruno

2018-05-01

Cylindrical storage tanks are widely used for various types of liquids, including hazardous contents, thus requiring suitable and careful design for seismic actions. The study herein presented deals with the dynamic analysis of a ground-based horizontal cylindrical tank containing butane and with its safety verification. The analyses are based on a detailed finite element (FE) model; a simplified one-degree-of-freedom idealization is also set up and used for verification of the FE results. Particular attention is paid to sloshing and asynchronous seismic input effects. Sloshing effects are investigated according to the current literature state of the art. An efficient methodology based on an "impulsive-convective" decomposition of the container-fluid motion is adopted for the calculation of the seismic force. The effects of asynchronous ground motion are studied by suitable pseudo-static analyses. Comparison between seismic action effects, obtained with and without consideration of sloshing and asynchronous seismic input, shows a rather important influence of these conditions on the final results.

Propagation of flexural and membrane waves with fluid loaded NASTRAN plate and shell elements

NASA Technical Reports Server (NTRS)

Kalinowski, A. J.; Wagner, C. A.

1983-01-01

Modeling of flexural and membrane type waves existing in various submerged (or in vacuo) plate and/or shell finite element models that are excited with steady state type harmonic loadings proportioned to e(i omega t) is discussed. Only thin walled plates and shells are treated wherein rotary inertia and shear correction factors are not included. More specifically, the issue of determining the shell or plate mesh size needed to represent the spatial distribution of the plate or shell response is of prime importance towards successfully representing the solution to the problem at hand. To this end, a procedure is presented for establishing guide lines for determining the mesh size based on a simple test model that can be used for a variety of plate and shell configurations such as, cylindrical shells with water loading, cylindrical shells in vacuo, plates with water loading, and plates in vacuo. The procedure for doing these four cases is given, with specific numerical examples present only for the cylindrical shell case.

Frequency-dependent processing and interpretation (FDPI) of seismic data for identifying, imaging and monitoring fluid-saturated underground reservoirs

DOEpatents

Goloshubin, Gennady M.; Korneev, Valeri A.

2006-11-14

A method for identifying, imaging and monitoring dry or fluid-saturated underground reservoirs using seismic waves reflected from target porous or fractured layers is set forth. Seismic imaging the porous or fractured layer occurs by low pass filtering of the windowed reflections from the target porous or fractured layers leaving frequencies below low-most corner (or full width at half maximum) of a recorded frequency spectra. Additionally, the ratio of image amplitudes is shown to be approximately proportional to reservoir permeability, viscosity of fluid, and the fluid saturation of the porous or fractured layers.

Frequency-dependent processing and interpretation (FDPI) of seismic data for identifying, imaging and monitoring fluid-saturated underground reservoirs

DOEpatents

Goloshubin, Gennady M.; Korneev, Valeri A.

2005-09-06

A method for identifying, imaging and monitoring dry or fluid-saturated underground reservoirs using seismic waves reflected from target porous or fractured layers is set forth. Seismic imaging the porous or fractured layer occurs by low pass filtering of the windowed reflections from the target porous or fractured layers leaving frequencies below low-most corner (or full width at half maximum) of a recorded frequency spectra. Additionally, the ratio of image amplitudes is shown to be approximately proportional to reservoir permeability, viscosity of fluid, and the fluid saturation of the porous or fractured layers.

Control of Thermal Convection in Layered Fluids Using Magnetic fields

NASA Technical Reports Server (NTRS)

Ramachandran, N.; Leslie, F. W.

2003-01-01

Immiscible fluid layers are found in a host of applications ranging from materials processing, for example the use of encapsulants in float zone crystal growth technique and a buffer layer in industrial Czochralski growth of crystals to prevent Marangoni convection, to heat transfer phenomena in day-to-day processes like the presence of air pockets in heat exchangers. In the microgravity and space processing realm, the exploration of other planets requires the development of enabling technologies in several fronts. The reduction in the gravity level poses unique challenges for fluid handling and heat transfer applications. The present work investigates the efficacy of controlling thermal convective flow using magnetic fluids and magnetic fields. The setup is a two-layer immiscible liquids system with one of the fluids being a diluted ferrofluid (super paramagnetic nano particles dispersed in carrier fluid). Using an external magnetic field one can essentially dial in a volumetric force - gravity level, on the magnetic fluid and thereby affect the system thermo-fluid behavior. The paper will describe the experimental and numerical modeling approach to the problem and discuss results obtained to date.

Engineering fluid flow using sequenced microstructures

NASA Astrophysics Data System (ADS)

Amini, Hamed; Sollier, Elodie; Masaeli, Mahdokht; Xie, Yu; Ganapathysubramanian, Baskar; Stone, Howard A.; di Carlo, Dino

2013-05-01

Controlling the shape of fluid streams is important across scales: from industrial processing to control of biomolecular interactions. Previous approaches to control fluid streams have focused mainly on creating chaotic flows to enhance mixing. Here we develop an approach to apply order using sequences of fluid transformations rather than enhancing chaos. We investigate the inertial flow deformations around a library of single cylindrical pillars within a microfluidic channel and assemble these net fluid transformations to engineer fluid streams. As these transformations provide a deterministic mapping of fluid elements from upstream to downstream of a pillar, we can sequentially arrange pillars to apply the associated nested maps and, therefore, create complex fluid structures without additional numerical simulation. To show the range of capabilities, we present sequences that sculpt the cross-sectional shape of a stream into complex geometries, move and split a fluid stream, perform solution exchange and achieve particle separation. A general strategy to engineer fluid streams into a broad class of defined configurations in which the complexity of the nonlinear equations of fluid motion are abstracted from the user is a first step to programming streams of any desired shape, which would be useful for biological, chemical and materials automation.

Development of sputtered techniques for thrust chambers, task 1. [evaluation of filler materials for regeneratively cooled thrust chambers

NASA Technical Reports Server (NTRS)

Mullaly, J. R.; Schmid, T. E.; Hecht, R. J.

1974-01-01

Filler materials proposed for use in the sputter fabrication regeneratively cooled thrust chambers were evaluated. Low melting castable alloys, CERROBEND. CERROCAST, and CERROTRU, slurry applied SERMETEL 481 and flame-sprayed aluminum were investigated as filler materials. Sputter deposition from a cylindrical cathode inverted magnestron was used to apply an OFHC copper closeout layer to filled OFHC copper ribbed-wall cylindrical substrates. The sputtered closeout layer structure was evaluated with respect to filler material contamination, predeposition machining and finishing operations, and deposition parameters. The application of aluminum by flame-spraying resulted in excessiver filler porosity. Though the outgassing from this porosity was found to be detrimental to the closeout layer structure, bond strengths in excess of 10,500 psi were achieved. Removal of the aluminum from the grooves was readily accomplished by leaching in a 7.0 molar solution of sodium hydroxide at 353 K. Of the other filler materials evaluated, CERROTRU was found to be the most suitable material with respect to completely filling the ribbed-wall cylinders and vacuum system compatibility. However, bond contamination resulted in low closeout layer bond strength with the CERROTRU filler. CERROBEND, CERROCAST, and SERMETEL 481 were found to be unacceptable as filler materials.

Thermohydrodynamic analysis of cryogenic liquid turbulent flow fluid film bearings, phase 2

NASA Technical Reports Server (NTRS)

Sanandres, Luis

1994-01-01

The Phase 2 (1994) Annual Progress Report presents two major report sections describing the thermal analysis of tilting- and flexure-pad hybrid bearings, and the unsteady flow and transient response of a point mass rotor supported on fluid film bearings. A literature review on the subject of two-phase flow in fluid film bearings and part of the proposed work for 1995 are also included. The programs delivered at the end of 1994 are named hydroflext and hydrotran. Both codes are fully compatible with the hydrosealt (1993) program. The new programs retain the same calculating options of hydrosealt plus the added bearing geometries, and unsteady flow and transient forced response. Refer to the hydroflext & hydrotran User's Manual and Tutorial for basic information on the analysis and instructions to run the programs. The Examples Handbook contains the test bearing cases along with comparisons with experimental data or published analytical values. The following major tasks were completed in 1994 (Phase 2): (1) extension of the thermohydrodynamic analysis and development of computer program hydroflext to model various bearing geometries, namely, tilting-pad hydrodynamic journal bearings, flexure-pad cylindrical bearings (hydrostatic and hydrodynamic), and cylindrical pad bearings with a simple elastic matrix (ideal foil bearings); (2) improved thermal model including radial heat transfer through the bearing stator; (3) calculation of the unsteady bulk-flow field in fluid film bearings and the transient response of a point mass rotor supported on bearings; and (4) a literature review on the subject of two-phase flows and homogeneous-mixture flows in thin-film geometries.

A New Paradigm for Turbulence Control for Drag Reduction

DTIC Science & Technology

2017-02-27

regions with different physical dynamics such as the low-turbulence suction region. C. Ekman Layer Flow and Modeling The Ekman layer19 is a boundary layer...S. Biringen, and P. P. Sullivan, J. Fluid Mech. 724, 581 (2013). 22 S. Waggy, S. Biringen, and A. Kucala, Geophysical and Astrophysical Fluid

Sound Transmission through Two Concentric Cylindrical Sandwich Shells

NASA Technical Reports Server (NTRS)

Tang, Yvette Y.; Silcox, Richard J.; Robinson, Jay H.

1996-01-01

This paper solves the problem of sound transmission through a system of two infinite concentric cylindrical sandwich shells. The shells are surrounded by external and internal fluid media and there is fluid (air) in the annular space between them. An oblique plane sound wave is incident upon the surface of the outer shell. A uniform flow is moving with a constant velocity in the external fluid medium. Classical thin shell theory is applied to the inner shell and first-order shear deformation theory is applied to the outer shell. A closed form for transmission loss is derived based on modal analysis. Investigations have been made for the impedance of both shells and the transmission loss through the shells from the exterior into the interior. Results are compared for double sandwich shells and single sandwich shells. This study shows that: (1) the impedance of the inner shell is much smaller than that of the outer shell so that the transmission loss is almost the same in both the annular space and the interior cavity of the shells; (2) the two concentric sandwich shells can produce an appreciable increase of transmission loss over single sandwich shells especially in the high frequency range; and (3) design guidelines may be derived with respect to the noise reduction requirement and the pressure in the annular space at a mid-frequency range.

Shipping container for fissile material

DOEpatents

Crowder, H.E.

1984-12-17

The present invention is directed to a shipping container for the interstate transportation of enriched uranium materials. The shipping container is comprised of a rigid, high-strength, cylindrical-shaped outer vessel lined with thermal insulation. Disposed inside the thermal insulation and spaced apart from the inner walls of the outer vessel is a rigid, high-strength, cylindrical inner vessel impervious to liquid and gaseous substances and having the inner surfaces coated with a layer of cadmium to prevent nuclear criticality. The cadmium is, in turn, lined with a protective shield of high-density urethane for corrosion and wear protection. 2 figs.

Cyclonic circulation of Saturn's atmosphere due to tilted convection

NASA Astrophysics Data System (ADS)

Afanasyev, Y. D.; Zhang, Y.

2018-03-01

Saturn displays cyclonic vortices at its poles and the general atmospheric circulation at other latitudes is dominated by embedded zonal jets that display cyclonic circulation. The abundance of small-scale convective storms suggests that convection plays a role in producing and maintaining Saturn's atmospheric circulation. However, the dynamical influence of small-scale convection on Saturn's general circulation is not well understood. Here we present laboratory analogue experiments and propose that Saturn's cyclonic circulation can be explained by tilted convection in which buoyancy forces do not align with the planet's rotation axis. In our experiments—conducted with a cylindrical water tank that is heated at the bottom, cooled at the top and spun on a rotating table—warm rising plumes and cold sinking water generate small anticyclonic and cyclonic vortices that are qualitatively similar to Saturn's convective storms. Numerical simulations complement the experiments and show that this small-scale convection leads to large-scale cyclonic flow at the surface and anticyclonic circulation at the base of the fluid layer, with a polar vortex forming from the merging of smaller cyclonic storms that are driven polewards.

Cylindrical Piezoelectric Fiber Composite Actuators

NASA Technical Reports Server (NTRS)

Allison, Sidney G.; Shams, Qamar A.; Fox, Robert L.

2008-01-01

The use of piezoelectric devices has become widespread since Pierre and Jacques Curie discovered the piezoelectric effect in 1880. Examples of current applications of piezoelectric devices include ultrasonic transducers, micro-positioning devices, buzzers, strain sensors, and clocks. The invention of such lightweight, relatively inexpensive piezoceramic-fiber-composite actuators as macro fiber composite (MFC) actuators has made it possible to obtain strains and displacements greater than those that could be generated by prior actuators based on monolithic piezoceramic sheet materials. MFC actuators are flat, flexible actuators designed for bonding to structures to apply or detect strains. Bonding multiple layers of MFC actuators together could increase force capability, but not strain or displacement capability. Cylindrical piezoelectric fiber composite (CPFC) actuators have been invented as alternatives to MFC actuators for applications in which greater forces and/or strains or displacements may be required. In essence, a CPFC actuator is an MFC or other piezoceramic fiber composite actuator fabricated in a cylindrical instead of its conventional flat shape. Cylindrical is used here in the general sense, encompassing shapes that can have circular, elliptical, rectangular or other cross-sectional shapes in the planes perpendicular to their longitudinal axes.

Reaction Rate of Small Diffusing Molecules on a Cylindrical Membrane

NASA Astrophysics Data System (ADS)

Straube, Ronny; Ward, Michael J.; Falcke, Martin

2007-10-01

Biomembranes consist of a lipid bi-layer into which proteins are embedded to fulfill numerous tasks in localized regions of the membrane. Often, the proteins have to reach these regions by simple diffusion. Motivated by the observation that IP3 receptor channels (IP3R) form clusters on the surface of the endoplasmic reticulum (ER) during ATP-induced calcium release, the reaction rate of small diffusing molecules on a cylindrical membrane is calculated based on the Smoluchowski approach. In this way, the cylindrical topology of the tubular ER is explicitly taken into account. The problem can be reduced to the solution of the diffusion equation on a finite cylindrical surface containing a small absorbing hole. The solution is constructed by matching appropriate `inner' and `outer' asymptotic expansions. The asymptotic results are compared with those from numerical simulations and excellent agreement is obtained. For realistic parameter sets, we find reaction rates in the range of experimentally measured clustering rates of IP3R. This supports the idea that clusters are formed by a purely diffusion limited process.

Spontaneous electrorheological effect in nematic liquid crystals under Taylor-Couette flow configuration

NASA Astrophysics Data System (ADS)

Dhar, Jayabrata; Chakraborty, Suman

2017-09-01

Electrorheological (ER) characteristics of Nematic Liquid Crystals (NLCs) have been a topic of immense interest in the field of soft matter physics owing to its rheological modulation capabilities. Here we explore the augmentation in rheological characteristics of the nematic fluid confined within the annular region of the concentric cylindrical space with an Electrical Double Layer (EDL) induced at the fluid-substrate interface due to certain physico-chemical interactions. Using a Taylor-Couette flow configuration associated with an EDL induced at the inner cylinder wall, we show that a spontaneous electrorheological effect is generated owing to the intrinsic director anisotropy and structural order of complex nematic fluids. We seek to find the enhancement in torque transfer capability due to the inherent electrorheological nature of the nematic medium, apart from exploiting the innate nature of such homogeneous media to remain free of coagulation, a fact which makes it an excellent candidate for the applications in microfluidic environment. Our analysis reveals that with stronger induced charge density within the EDL, the apparent viscosity enhances, which, in turn, augments torque transfer across the concentric cylinder. The velocity profile tends to flatten in comparison to the classical circular Couette flow in annular geometry as one increases the surface charge density. We further observe a more pronounced ER effect for the nematic medium having larger electrical permittivity anisotropy. Besides the torque transfer qualifications, we also explore the distinct scenarios, wherein the same NLC medium exhibits shear thinning and shear thickening characteristics. The present configuration of the efficient torque transfer mechanism may be proficiently downscaled to micro-level and is relevant in the fabrication of micro-clutch and micro-dampers.

Deformation of Fluid Column by Action of Axial Vibration and Some Aspects of High-Rate Thermocapillary Convection

NASA Technical Reports Server (NTRS)

Feonychev, Alexander I.; Kalachinskaya, Irina S.; Pokhilko, Victor I.

1996-01-01

The deformation of the fluid column by an action of a low-frequency vibration is considered. It is shown that behavior of the free fluid surface depends on the frequency of applied vibration and its amplitude. In the area of very low frequencies when fluid has time to comment on travel of bounding solid walls limiting column, the harmonical oscillations of free surface with given frequency are observed. With increase of vibration frequency the steady-state relief on free fluid surface is formed. If the amplitude of vibration is very small and the frequency corresponding to the first peak in the vibration spectrum on the Mir orbital station, the deformation of free surface tends to zero. Fluid flow induced thermocapillary effect on deformed free surface is more unstable as in the case of smooth cylindrical surface. It was shown that width of heating zone affects very essentially the flow pattern and transition to oscillatory regime of thermocapillary convection.

The structure of carbon nanotubes formed of graphene layers L4-8, L5-7, L3-12, L4-6-12

NASA Astrophysics Data System (ADS)

Shapovalova, K. E.; Belenkov, E. A.

2017-11-01

We geometrically calculate the optimized structure of nanotubes based on the graphene layers, using the method of molecular mechanics MM+. It was found that only the nanotubes, based on the graphene layers L4-8, L5-7, L3-12, L4-6-12, have a cylindrical form. Calculations of the sublimation energy, carried out using the semi-empirical quantum-mechanic method PM3, show that energy increases with the increase of nanotube diameters.

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

Seletskiy, S.; Fedotov, A.; Gassner, D.

The goal of this note is to set basic parameters for the magnetic shielding of LEReC CS with required design attenuation. We considered physical design of magnetic shielding of LEReC cooling section. The schematic of this design along with the list of its basic parameters is shown. We are planning to use 2 layers of 1 mm thick cylindrical mu-metal shields with μ=11000. The radius of the first layer sitting on top of vacuum chamber is 63.5 mm. The second layer radius is 150 mm. Such shielding guarantees adequate transverse angles of electron beam trajectory in the CS.

Simultaneous Multiple-Location Separation Control

NASA Technical Reports Server (NTRS)

Greenblatt, David (Inventor)

2009-01-01

A method of controlling a shear layer for a fluid dynamic body introduces first periodic disturbances into the fluid medium at a first flow separation location. Simultaneously, second periodic disturbances are introduced into the fluid medium at a second flow separation location. A phase difference between the first and second periodic disturbances is adjusted to control flow separation of the shear layer as the fluid medium moves over the fluid dynamic body.

Falkner-Skan Boundary Layer Flow of a Sisko Fluid

NASA Astrophysics Data System (ADS)

Khan, Masood; Shahzad, Azeem

2012-09-01

In this paper, we investigate the steady boundary layer flow of a non-Newtonian fluid, represented by a Sisko fluid, over a wedge in a moving fluid. The equations of motion are derived for boundary layer flow of an incompressible Sisko fluid using appropriate similarity variables. The governing equations are reduced to a single third-order highly nonlinear ordinary differential equation in the dimensionless stream function, which is then solved analytically using the homotopy analysis method. Some important parameters have been discussed by this study, which include the power law index n, the material parameter A, the wedge shape factor b, and the skin friction coefficient Cf. A comprehensive study is made between the results of the Sisko and the power-law fluids.

Generic instabilities in a fluid membrane coupled to a thin layer of ordered active polar fluid.

PubMed

Sarkar, Niladri; Basu, Abhik

2013-08-01

We develop an effective two-dimensional coarse-grained description for the coupled system of a planar fluid membrane anchored to a thin layer of polar ordered active fluid below. The macroscopic orientation of the active fluid layer is assumed to be perpendicular to the attached membrane. We demonstrate that activity or nonequilibrium drive of the active fluid makes such a system generically linearly unstable for either signature of a model parameter [Formula: see text] [Formula: see text] that characterises the strength of activity. Depending upon boundary conditions and within a range of the model parameters, underdamped propagating waves may be present in our model. We discuss the phenomenological significance of our results.

Encapsulated proppants

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

Aines, Roger D.; Bourcier, William L.; Duoss, Eric B.

2018-01-30

A capsule for carrying a proppant for emplaced in a formation containing formation fluid by a hydraulic fracture operation using a fracturing fluid. The capsule includes a capsule body. The capsule body includes a proppant. There is a surface layer on the capsule body that is permeable to the formation fluid or the fracturing fluid or is permeable to both the formation fluid and the fracturing fluid. The proppant material is dry cement that interacts with the formation fluid or the fracturing fluid or both the formation fluid and the fracturing fluid that migrate through the surface layer and ismore » taken up by the dry cement causing the dry cement to harden.« less

Encapsulated proppants

DOEpatents

Aines, Roger D.; Bourcier, William L.; Duoss, Eric B.; Roberts, Jeffery James; Spadaccini, Christopher M.; Stolaroff, Joshuah K.

2018-01-09

A capsule for carrying a proppant for emplaced in a formation containing formation fluid by a hydraulic fracture operation using a fracturing fluid. The capsule includes a capsule body. The capsule body includes a proppant. There is a surface layer on the capsule body that is permeable to the formation fluid or the fracturing fluid or is permeable to both the formation fluid and the fracturing fluid. The proppant material is dry cement that interacts with the formation fluid or the fracturing fluid or both the formation fluid and the fracturing fluid that migrate through the surface layer and is taken up by the dry cement causing the dry cement to harden.

Trapped-mode-induced Fano resonance and acoustical transparency in a one-dimensional solid-fluid phononic crystal

NASA Astrophysics Data System (ADS)

Quotane, Ilyasse; El Boudouti, El Houssaine; Djafari-Rouhani, Bahram

2018-01-01

We investigate theoretically and numerically the possibility of existence of Fano and acoustic-induced transparency (AIT) resonances in a simple though realistic one-dimensional acoustic structure made of solid-fluid layers inserted between two fluids. These resonances are obtained by combining appropriately the zeros of transmission (antiresonance) induced by the solid layers and the local resonances induced by the solid or combined solid-fluid layers with surface free boundary conditions. In particular, we show the possibility of trapped modes, also called bound states in continuum, which have recently found a high renewal interest. These modes appear as resonances with zero width in the transmission spectra as well as in the density of states (DOS). We consider three different structures: (i) a single solid layer inserted between two fluids. This simple structure shows the possibility of existence of trapped modes, which are discrete modes of the solid layer that lie in the continuum modes of the surrounding fluids. We give explicit analytical expressions of the dispersion relation of these eigenmodes of the solid layer which are found independent of the nature of the surrounding fluids. By slightly detuning the angle of incidence from that associated to the trapped mode, we get a well-defined Fano resonance characterized by an asymmetric Fano profile in the transmission spectra. (ii) The second structure consists of a solid-fluid-solid triple layer embedded between two fluids. This structure is found more appropriate to show both Fano and acoustic-induced transparency resonances. We provide detailed analytical expressions for the transmission and reflection coefficients that enable us to deduce a closed-form expression of the dispersion relation giving the trapped modes. Two situations can be distinguished in the triple-layer system: in the case of a symmetric structure (i.e., the same solid layers) we show, by detuning the incidence angle θ , the possibility of existence of Fano resonances that can be fitted following a Fano-type expression. The variation of the Fano parameter that describes the asymmetry of such resonances as well as their width versus θ is studied in detail. In the case of an asymmetric structure (i.e., different solid layers), we show the existence of an incidence angle that enables to squeeze a resonance between two transmission zeros induced by the two solid layers. This resonance behaves like an AIT resonance, its position and width depend on the nature of the fluid and solid layers as well as on the difference between the thicknesses of the solid layers. (iii) In the case of a periodic structure (phononic crystal), we show that trapped modes and Fano resonances give rise, respectively, to dispersionless flat bands with zero group velocity and nearly flat bands with negative or positive group velocities. The analytical results presented here are obtained by means of the Green's function method which enables to deduce in closed form: dispersion curves, transmission and reflection coefficients, DOS, as well as the displacement fields. The proposed solid-fluid layered structures should have important applications for designing acoustic mirrors and acoustic filters as well as supersonic and subsonic materials.

Beyond the single-file fluid limit using transfer matrix method: Exact results for confined parallel hard squares

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

Gurin, Péter; Varga, Szabolcs

2015-06-14

We extend the transfer matrix method of one-dimensional hard core fluids placed between confining walls for that case where the particles can pass each other and at most two layers can form. We derive an eigenvalue equation for a quasi-one-dimensional system of hard squares confined between two parallel walls, where the pore width is between σ and 3σ (σ is the side length of the square). The exact equation of state and the nearest neighbor distribution functions show three different structures: a fluid phase with one layer, a fluid phase with two layers, and a solid-like structure where the fluidmore » layers are strongly correlated. The structural transition between differently ordered fluids develops continuously with increasing density, i.e., no thermodynamic phase transition occurs. The high density structure of the system consists of clusters with two layers which are broken with particles staying in the middle of the pore.« less

Design of the Coordinate Transformation Function for Cylindrical Acoustic Cloaks with a Quantity of Discrete Layers

NASA Astrophysics Data System (ADS)

Cai, Li; Wen, Ji-Hong; Yu, Dian-Long; Lu, Zhi-Miao; Wen, Xi-Sen

2014-09-01

Acoustic cloak based on coordinate transformation is of great topical interest and has promise in potential applications such as sound transparency and insulation. The frequency response of acoustic cloaks with a quantity of discrete homogeneous layers is analyzed by the acoustic scattering theory. The effect of coordinate transformation function on the acoustic total scattering cross section is discussed to achieve low scattering with only a few layers of anisotropic metamaterials. Also, the physics of acoustic wave interaction with the interfaces between the discrete layers inside the cloak shell is discussed. These results provide a better way of designing a multilayered acoustic cloak with fewer layers.

A numerical method for electro-kinetic flow with deformable fluid interfaces

NASA Astrophysics Data System (ADS)

Booty, Michael; Ma, Manman; Siegel, Michael

2013-11-01

We consider two-phase flow of ionic fluids whose motion is driven by an imposed electric field. At a fluid interface, a screening cloud of ions develops and forms an electro-chemical double layer or Debye layer. The imposed field acts on this induced charge distribution, resulting in a strong slip flow near the interface. We formulate a ``hybrid'' or multiscale numerical method in the thin Debye layer limit that incorporates an asymptotic analysis of the electrostatic potential and fluid dynamics in the Debye layer into a boundary integral solution of the full moving boundary problem. Results of the method are presented that show time-dependent deformation and steady state drop interface shapes when the timescale for charge-up of the Debye layer is either much less than or comparable to the timescale of the flow.

Segmented lasing tube for high temperature laser assembly

DOEpatents

Sawicki, Richard H.; Alger, Terry W.; Finucane, Raymond G.; Hall, Jerome P.

1996-01-01

A high temperature laser assembly capable of withstanding operating temperatures in excess of 1500.degree. C. is described comprising a segmented cylindrical ceramic lasing tube having a plurality of cylindrical ceramic lasing tube segments of the same inner and outer diameters non-rigidly joined together in axial alignment; insulation of uniform thickness surround the walls of the ceramic lasing tube; a ceramic casing, preferably of quartz, surrounding the insulation; and a fluid cooled metal jacket surrounds the ceramic casing. In a preferred embodiment, the inner surface of each of the ceramic lasing tube segments are provided with a pair of oppositely spaced grooves in the wall thereof parallel to the center axis of the segmented cylindrical ceramic lasing tube, and both of the grooves and the center axis of the segmented cylindrical ceramic lasing tube lie in a common plane, with the grooves in each ceramic lasing tube segment in circumferential alignment with the grooves in the adjoining ceramic lasing tube segments; and one or more ceramic plates, all lying in a common plane to one another and with the central axis of the segmented ceramic lasing tube, are received in the grooves to provide additional wall area in the segmented ceramic lasing tube for collision and return to ground state of metastable metal atoms within the segmented ceramic lasing tube.

Development of a Constitutive Model Predicting the Point of Short-Circuit Within Lithium-Ion Battery Cells

DTIC Science & Technology

2012-06-01

polyolefin layer, typically polypropylene or polyethylene. The separator keeps the anodic and cathodic layers from touching. An internal short-circuit is...be seen that there are both spot welds and laser welds are used in the construction of the individual cylindrical cell. When constructing larger...manufacturing, to include resistance welding, laser welding, ultrasonic welding, and mechanical joining are detailed in Shawn Lee, S., et al(2010) (9

Time-dependent dynamical behavior of surface tension on rotating fluids under microgravity environment

NASA Technical Reports Server (NTRS)

Hung, R. J.; Tsao, Y. D.; Hong, B. B.; Leslie, F. W.

1988-01-01

Time dependent evolutions of the profile of free surface (bubble shapes) for a cylindrical container partially filled with a Newtonian fluid of constant density, rotating about its axis of symmetry, have been studied. Numerical computations of the dynamics of bubble shapes have been carried out with the following situations: (1) linear functions of spin-up and spin-down in low and microgravity environments, (2) step functions of spin-up and spin-down in a low gravity environment, and (3) sinusoidal function oscillation of gravity environment in high and low rotating cylinder speeds.

Glacial uplift: fluid injection beneath an elastic sheet on a poroelastic substrate

NASA Astrophysics Data System (ADS)

Neufeld, Jerome; Hewitt, Duncan; Chini, Greg

2016-11-01

Supraglacial lakes can drain to the base of glaciers extremely rapidly, causing localised uplift of the surrounding glacier and affecting its sliding velocity. The means by which large volumes of drained water interact with and leak into the subglacial hydrological system is unclear, as is the role of the basal till. A theoretical study of the spread of fluid injected below an elastic sheet (the ice) is presented, where the ice lies above, and initially compresses, a deformable poroelastic layer. As pressurized fluid is injected, the deformable layer swells to accommodate more fluid. If sufficient fluid is injected, a 'blister' of fluid forms above the layer, causing the overburden to lift off the base. The flow is controlled by the local pressure drop across the tip of this blister, which depends subtly on both the flow of fluid through the porous layer below the tip, and on poroelastic deformation in the till ahead of the tip. The spreading behaviour and dependence on key parameters is analysed. Predictions of the model are compared to field measurements of uplift from draining glacial lakes in Greenland.

Self-regulating chemo-mechano-chemical systems

DOEpatents

Aizenberg, Joanna; He, Ximin; Aizenberg, Michael

2017-05-16

A chemo-mechano-chemical (C.sub.1-M-C.sub.2) system includes a base supporting an actuatable structure, said structure comprising a functionalized portion and being embedded in an environmentally responsive gel capable of volume change in response to an environmental stimulus; a first fluid layer disposed over the base and in contact with the actuatable structure, said first fluid layer comprising the environmentally responsive gel; and a second fluid layer in contact with the actuatable structure, wherein the layers are positioned such that the functionalized portion is in contact with the second layer in a first relaxed state and in contact with the first layer in a second actuated state and wherein the functionalized portion interacts with at least one of the layers to provide a chemical or physical response.

Transition from Selective Withdrawal to Light Layer Entrainment in an Oil-Water System

NASA Astrophysics Data System (ADS)

Hartenberger, Joel; O'Hern, Timothy; Webb, Stephen; James, Darryl

2010-11-01

Selective withdrawal refers to the selective removal of fluid of one density without entraining an adjacent fluid layer of a different density. Most prior literature has examined removal of the lower density fluid and the transition to entraining the higher density fluid. In the present experiments, a higher density liquid is removed through a tube that extends just below its interface with a lower density fluid. The critical depth for a given flow rate at which the liquid-liquid interface transitions to entrain the lighter fluid was measured. Experiments were performed for a range of different light layer silicone oils and heavy layer water or brine, covering a range of density and viscosity ratios. Applications include density-stratified reservoirs and brine removal from oil storage caverns. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Instabilities and diffusion in a hydrodynamic model of a fluid membrane coupled to a thin active fluid layer.

PubMed

Sarkar, N; Basu, A

2012-11-01

We construct a coarse-grained effective two-dimensional (2d hydrodynamic theory as a theoretical model for a coupled system of a fluid membrane and a thin layer of a polar active fluid in its ordered state that is anchored to the membrane. We show that such a system is prone to generic instabilities through the interplay of nonequilibrium drive, polar order and membrane fluctuation. We use our model equations to calculate diffusion coefficients of an inclusion in the membrane and show that their values depend strongly on the system size, in contrast to their equilibrium values. Our work extends the work of S. Sankararaman and S. Ramaswamy (Phys. Rev. Lett., 102, 118107 (2009)) to a coupled system of a fluid membrane and an ordered active fluid layer. Our model is broadly inspired by and should be useful as a starting point for theoretical descriptions of the coupled dynamics of a cell membrane and a cortical actin layer anchored to it.

Dedicated vertical wind tunnel for the study of sedimentation of non-spherical particles.

PubMed

Bagheri, G H; Bonadonna, C; Manzella, I; Pontelandolfo, P; Haas, P

2013-05-01

A dedicated 4-m-high vertical wind tunnel has been designed and constructed at the University of Geneva in collaboration with the Groupe de compétence en mécanique des fluides et procédés énergétiques. With its diverging test section, the tunnel is designed to study the aero-dynamical behavior of non-spherical particles with terminal velocities between 5 and 27 ms(-1). A particle tracking velocimetry (PTV) code is developed to calculate drag coefficient of particles in standard conditions based on the real projected area of the particles. Results of our wind tunnel and PTV code are validated by comparing drag coefficient of smooth spherical particles and cylindrical particles to existing literature. Experiments are repeatable with average relative standard deviation of 1.7%. Our preliminary experiments on the effect of particle to fluid density ratio on drag coefficient of cylindrical particles show that the drag coefficient of freely suspended particles in air is lower than those measured in water or in horizontal wind tunnels. It is found that increasing aspect ratio of cylindrical particles reduces their secondary motions and they tend to be suspended with their maximum area normal to the airflow. The use of the vertical wind tunnel in combination with the PTV code provides a reliable and precise instrument for measuring drag coefficient of freely moving particles of various shapes. Our ultimate goal is the study of sedimentation and aggregation of volcanic particles (density between 500 and 2700 kgm(-3)) but the wind tunnel can be used in a wide range of applications.

Conformal SiO2 coating of sub-100 nm diameter channels of polycarbonate etched ion-track channels by atomic layer deposition

PubMed Central

Sobel, Nicolas; Lukas, Manuela; Spende, Anne; Stühn, Bernd; Trautmann, Christina

2015-01-01

Summary Polycarbonate etched ion-track membranes with about 30 µm long and 50 nm wide cylindrical channels were conformally coated with SiO2 by atomic layer deposition (ALD). The process was performed at 50 °C to avoid thermal damage to the polymer membrane. Analysis of the coated membranes by small angle X-ray scattering (SAXS) reveals a homogeneous, conformal layer of SiO2 in the channels at a deposition rate of 1.7–1.8 Å per ALD cycle. Characterization by infrared and X-ray photoelectron spectroscopy (XPS) confirms the stoichiometric composition of the SiO2 films. Detailed XPS analysis reveals that the mechanism of SiO2 formation is based on subsurface crystal growth. By dissolving the polymer, the silica nanotubes are released from the ion-track membrane. The thickness of the tube wall is well controlled by the ALD process. Because the track-etched channels exhibited diameters in the range of nanometres and lengths in the range of micrometres, cylindrical tubes with an aspect ratio as large as 3000 have been produced. PMID:25821688

Characteristics of contaminant deposition onto a cylindrical body surrounded by porous clothing

NASA Astrophysics Data System (ADS)

Cho, Minki; Lee, Jinwon; Jung, Hyunsuk; Lee, Haewan; Pohang Univ of Sci; Tech Team; AgencyDefense Development Team

2014-11-01

In order to characterize the deposition pattern of air-borne contaminants on a human body protected by a garment, the air flow through the clothing and in the air gap between the clothing and the skin was numerically solved, and the deposition of the suspended contaminants on the skin was obtained over a wide variety of conditions-wind speed, human motion and clothing conditions. The penetrating air flow was sensitive to the pressure inside the air gap, for which a simple model was successfully formulated. Also the profile of the non-uniform deposition velocity or the Sherwood number could be well modeled based on the developing concentration boundary layer inside the air gap. The boundary layer thickness grew vary rapidly, nearly proportional to the square of the distance from the front stagnation point, which is much different from any other boundary layer studied in many engineering fields before. A rather universal function for the distribution of deposition speed over a cylindrical body was obtained, which remained valid for a very wide range of conditions. The characteristics for non-uniform and/or periodic external wind due to human motion were also analyzed. This study is supported by Agency for Defense Development.

Development of selective surfaces. Semiannual technical progress report, September 11, 1978-April 30, 1979. [Multilayer coatings

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

Thornton, J.A.

1979-06-15

Magnetron sputtering technology, which permits coatings to be deposited over large areas with significantly increased deposition rates, is reviewed with particular emphasis on cylindrical magnetrons and their application to reactive sputtering. Work is reported in which cylindrical-post magnetron sputtering sources have been used to deposit both graded and multi-layered cermet-type coatings by sputtering chromium and type 304 stainless steel in Ar and O/sub 2/ and Ar and CO gas mixtures under various conditions of reactive gas injection. The substrates are aluminum-coated glass and aluminum foil. The coatings are of an interference type, typically about 100 nm thick, with a metal-rich,more » highly absorbing layer adjacent to the substrate and a dielectric material at the surface. In some cases a reactively sputtered aluminum oxide anti-reflective surface layer has also been used. No advantages have been found for using chromium as opposed to the more readily available stainless steel. The reactive sputtering with CO is attractive because under many conditions the sputtering rates are relatively large compared to oxygen. Hemispherical absorptance and emittance data are reported. Typical absorptances are about 0.90 with emittances of 0.10.« less

Polyelectrolyte layer-by-layer deposition in cylindrical nanopores.

PubMed

Lazzara, Thomas D; Lau, K H Aaron; Abou-Kandil, Ahmed I; Caminade, Anne-Marie; Majoral, Jean-Pierre; Knoll, Wolfgang

2010-07-27

Layer-by-layer (LbL) deposition of polyelectrolytes within nanopores in terms of the pore size and the ionic strength was experimentally studied. Anodic aluminum oxide (AAO) membranes, which have aligned, cylindrical, nonintersecting pores, were used as a model nanoporous system. Furthermore, the AAO membranes were also employed as planar optical waveguides to enable in situ monitoring of the LbL process within the nanopores by optical waveguide spectroscopy (OWS). Structurally well-defined N,N-disubstituted hydrazine phosphorus-containing dendrimers of the fourth generation, with peripherally charged groups and diameters of approximately 7 nm, were used as the model polyelectrolytes. The pore diameter of the AAO was varied between 30-116 nm and the ionic strength was varied over 3 orders of magnitude. The dependence of the deposited layer thickness on ionic strength within the nanopores is found to be significantly stronger than LbL deposition on a planar surface. Furthermore, deposition within the nanopores can become inhibited even if the pore diameter is much larger than the diameter of the G4-polyelectrolyte, or if the screening length is insignificant relative to the dendrimer diameter at high ionic strengths. Our results will aid in the template preparation of polyelectrolyte multilayer nanotubes, and our experimental approach may be useful for investigating theories regarding the partitioning of nano-objects within nanopores where electrostatic interactions are dominant. Furthermore, we show that the enhanced ionic strength dependence of polyelectrolyte transport within the nanopores can be used to selectively deposit a LbL multilayer atop a nanoporous substrate.

Cylindrical cryogenic calorimeter testing of six types of multilayer insulation systems

NASA Astrophysics Data System (ADS)

Fesmire, J. E.; Johnson, W. L.

2018-01-01

Extensive cryogenic thermal testing of more than 100 different multilayer insulation (MLI) specimens was performed over the last 20 years for the research and development of evacuated reflective thermal insulation systems. From this data library, 26 MLI systems plus several vacuum-only systems are selected for analysis and comparison. The test apparatus, methods, and results enabled the adoption of two new technical consensus standards under ASTM International. Materials tested include reflectors of aluminum foil or double-aluminized Mylar and spacers of fiberglass paper, polyester netting, silk netting, polyester fabric, or discrete polymer standoffs. The six types of MLI systems tested are listed as follows: Mylar/Paper, Foil/Paper, Mylar/Net, Mylar/Blanket, Mylar/Fabric, Mylar/Discrete. Also tested are vacuum-only systems with different cold surface materials/finishes including stainless steel, black, copper, and aluminum. Testing was performed between the boundary temperatures of 78 K and 293 K (and up to 350 K) using a thermally guarded one-meter-long cylindrical calorimeter (Cryostat-100) for absolute heat flow measurement. Cold vacuum pressures include the full range from 1 × 10-6 torr to 760 torr with nitrogen as the residual gas. System variations include number of layers from one to 80 layers, layer densities from 0.5 to 5 layers per millimeter, and installation techniques such layer-by-layer, blankets (multi-layer assemblies), sub-blankets, seaming, butt-joining, spiral wrapping, and roll-wrapping. Experimental thermal performance data for the different MLI systems are presented in terms of heat flux and effective thermal conductivity. Benchmark cryogenic-vacuum thermal performance curves for MLI are given for comparison with different insulation approaches for storage and transfer equipment, cryostats, launch vehicles, spacecraft, or science instruments.

Fluid transition layer between rigid solute and liquid solvent: is there depletion or enrichment?

PubMed

Djikaev, Yuri S; Ruckenstein, Eli

2016-03-21

The fluid layer between solute and liquid solvent is studied by combining the density functional theory with the probabilistic hydrogen bond model. This combination allows one to obtain the equilibrium distribution of fluid molecules, taking into account the hydrogen bond contribution to the external potential whereto they are subjected near the solute. One can find the effective width of the fluid solvent-solute transition layer and fluid average density in that layer, and determine their dependence on temperature, solvent-solute affinity, vicinal hydrogen bond (hb) energy alteration ratio, and solute radius. Numerical calculations are performed for the solvation of a plate and spherical solutes of four different radii in two model solvents (associated liquid and non-associated one) in the temperature range from 293 K to 333 K for various solvent-solute affinities and hydrogen bond energy alteration ratios. The predictions of our model for the effective width and average density of the transition layer are consistent with experiments and simulations. The small-to-large crossover lengthscale for hydrophobic hydration is expected to be about 3-5 nm. Remarkably, characterizing the transition layer with the average density, one can observe that for small hydrophobes, the transition layer becomes enriched with rather than depleted of fluid when the solvent-solute affinity and hb-energy alteration ratio become large enough. The boundary values of solvent-solute affinity and hb-energy alteration ratio, needed for the "depletion-to-enrichment" crossover (in the smoothed density sense), are predicted to decrease with increasing temperature.

Surface thermodynamics of planar, cylindrical, and spherical vapour-liquid interfaces of water

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

Lau, Gabriel V.; Müller, Erich A.; Jackson, George

2015-03-21

The test-area (TA) perturbation approach has been gaining popularity as a methodology for the direct computation of the interfacial tension in molecular simulation. Though originally implemented for planar interfaces, the TA approach has also been used to analyze the interfacial properties of curved liquid interfaces. Here, we provide an interpretation of the TA method taking the view that it corresponds to the change in free energy under a transformation of the spatial metric for an affine distortion. By expressing the change in configurational energy of a molecular configuration as a Taylor expansion in the distortion parameter, compact relations are derivedmore » for the interfacial tension and its energetic and entropic components for three different geometries: planar, cylindrical, and spherical fluid interfaces. While the tensions of the planar and cylindrical geometries are characterized by first-order changes in the energy, that of the spherical interface depends on second-order contributions. We show that a greater statistical uncertainty is to be expected when calculating the thermodynamic properties of a spherical interface than for the planar and cylindrical cases, and the evaluation of the separate entropic and energetic contributions poses a greater computational challenge than the tension itself. The methodology is employed to determine the vapour-liquid interfacial tension of TIP4P/2005 water at 293 K by molecular dynamics simulation for planar, cylindrical, and spherical geometries. A weak peak in the curvature dependence of the tension is observed in the case of cylindrical threads of condensed liquid at a radius of about 8 Å, below which the tension is found to decrease again. In the case of spherical drops, a marked decrease in the tension from the planar limit is found for radii below ∼ 15 Å; there is no indication of a maximum in the tension with increasing curvature. The vapour-liquid interfacial tension tends towards the planar limit for large system sizes for both the cylindrical and spherical cases. Estimates of the entropic and energetic contributions are also evaluated for the planar and cylindrical geometries and their magnitudes are in line with the expectations of our simple analysis.« less

Diffusion of Supercritical Fluids through Single-Layer Nanoporous Solids: Theory and Molecular Simulations.

PubMed

Oulebsir, Fouad; Vermorel, Romain; Galliero, Guillaume

2018-01-16

With the advent of graphene material, membranes based on single-layer nanoporous solids appear as promising devices for fluid separation, be it liquid or gaseous mixtures. The design of such architectured porous materials would greatly benefit from accurate models that can predict their transport and separation properties. More specifically, there is no universal understanding of how parameters such as temperature, fluid loading conditions, or the ratio of the pore size to the fluid molecular diameter influence the permeation process. In this study, we address the problem of pure supercritical fluids diffusing through simplified models of single-layer porous materials. Basically, we investigate a toy model that consists of a single-layer lattice of Lennard-Jones interaction sites with a slit gap of controllable width. We performed extensive equilibrium and biased molecular dynamics simulations to document the physical mechanisms involved at the molecular scale. We propose a general constitutive equation for the diffusional transport coefficient derived from classical statistical mechanics and kinetic theory, which can be further simplified in the ideal gas limit. This transport coefficient relates the molecular flux to the fluid density jump across the single-layer membrane. It is found to be proportional to the accessible surface porosity of the single-layer porous solid and to a thermodynamic factor accounting for the inhomogeneity of the fluid close to the pore entrance. Both quantities directly depend on the potential of mean force that results from molecular interactions between solid and fluid atoms. Comparisons with the simulations data show that the kinetic model captures how narrowing the pore size below the fluid molecular diameter lowers dramatically the value of the transport coefficient. Furthermore, we demonstrate that our general constitutive equation allows for a consistent interpretation of the intricate effects of temperature and fluid loading conditions on the permeation process.

Detection of chlorinated aromatic compounds

DOEpatents

Ekechukwu, A.A.

1996-02-06

A method for making a composition for measuring the concentration of chlorinated aromatic compounds in aqueous fluids, and an optical probe for use with the method are disclosed. The composition comprises a hydrophobic polymer matrix, preferably polyamide, with a fluorescent indicator uniformly dispersed therein. The indicator fluoresces in the presence of the chlorinated aromatic compounds with an intensity dependent on the concentration of these compounds in the fluid of interest, such as 8-amino-2-naphthalene sulfonate. The probe includes a hollow cylindrical housing that contains the composition in its distal end. The probe admits an aqueous fluid to the probe interior for exposure to the composition. An optical fiber transmits excitation light from a remote source to the composition while the indicator reacts with chlorinated aromatic compounds present in the fluid. The resulting fluorescence light signal is reflected to a second optical fiber that transmits the light to a spectrophotometer for analysis. 5 figs.

Fluidic angular velocity sensor

NASA Technical Reports Server (NTRS)

Berdahl, C. M. (Inventor)

1986-01-01

A fluidic sensor providing a differential pressure signal proportional to the angular velocity of a rotary input is described. In one embodiment the sensor includes a fluid pump having an impeller coupled to a rotary input. A housing forming a constricting fluid flow chamber is connected to the fluid input of the pump. The housing is provided with a fluid flow restrictive input to the flow chamber and a port communicating with the interior of the flow chamber. The differential pressure signal measured across the flow restrictive input is relatively noise free and proportional to the square of the angular velocity of the impeller. In an alternative embodiment, the flow chamber has a generally cylindrical configuration and plates having flow restrictive apertures are disposed within the chamber downstream from the housing port. In this embodiment, the differential pressure signal is found to be approximately linear with the angular velocity of the impeller.

Detection of chlorinated aromatic compounds

DOEpatents

Ekechukwu, Amy A.

1996-01-01

A method for making a composition for measuring the concentration of chloated aromatic compounds in aqueous fluids, and an optical probe for use with the method. The composition comprises a hydrophobic polymer matrix, preferably polyamide, with a fluorescent indicator uniformly dispersed therein. The indicator fluoresces in the presence of the chlorinated aromatic compounds with an intensity dependent on the concentration of these compounds in the fluid of interest, such as 8-amino-2-naphthalene sulfonate. The probe includes a hollow cylindrical housing that contains the composition in its distal end. The probe admits an aqueous fluid to the probe interior for exposure to the composition. An optical fiber transmits excitation light from a remote source to the composition while the indicator reacts with chlorinated aromatic compounds present in the fluid. The resulting fluorescence light signal is reflected to a second optical fiber that transmits the light to a spectrophotometer for analysis.

Exact Solutions for Stationary and Unsteady Layered Convection of a Viscous Incompressible Fluid with the Specified Velocities at the Bottom

NASA Astrophysics Data System (ADS)

Prosviryakov, E. Yu; Spevak, L. F.

2017-06-01

The layered convective flow of a viscous incompressible fluid is considered with the specified velocities at the bottom of an infinite layer. A new exact stationary and nonstationary solution of the Oberbeck-Boussinesq system is presented. The account of fluid velocity at the bottom is characterized by the presence of two stagnant points, this being indicative of the nonmonotonic kinetic energy profile with two local extrema.

Wrinkling pattern evolution of cylindrical biological tissues with differential growth.

PubMed

Jia, Fei; Li, Bo; Cao, Yan-Ping; Xie, Wei-Hua; Feng, Xi-Qiao

2015-01-01

Three-dimensional surface wrinkling of soft cylindrical tissues induced by differential growth is explored. Differential volumetric growth can cause their morphological stability, leading to the formation of hexagonal and labyrinth wrinkles. During postbuckling, multiple bifurcations and morphological transitions may occur as a consequence of continuous growth in the surface layer. The physical mechanisms underpinning the morphological evolution are examined from the viewpoint of energy. Surface curvature is found to play a regulatory role in the pattern evolution. This study may not only help understand the morphogenesis of soft biological tissues, but also inspire novel routes for creating desired surface patterns of soft materials.

Micropore extrusion-induced alignment transition from perpendicular to parallel of cylindrical domains in block copolymers.

PubMed

Qu, Ting; Zhao, Yongbin; Li, Zongbo; Wang, Pingping; Cao, Shubo; Xu, Yawei; Li, Yayuan; Chen, Aihua

2016-02-14

The orientation transition from perpendicular to parallel alignment of PEO cylindrical domains of PEO-b-PMA(Az) films has been demonstrated by extruding the block copolymer (BCP) solutions through a micropore of a plastic gastight syringe. The parallelized orientation of PEO domains induced by this micropore extrusion can be recovered to perpendicular alignment via ultrasonication of the extruded BCP solutions and subsequent annealing. A plausible mechanism is proposed in this study. The BCP films can be used as templates to prepare nanowire arrays with controlled layers, which has enormous potential application in the field of integrated circuits.

Model of depositing layer on cylindrical surface produced by induction-assisted laser cladding process

NASA Astrophysics Data System (ADS)

Kotlan, Václav; Hamar, Roman; Pánek, David; Doležel, Ivo

2017-12-01

A model of hybrid cladding on a cylindrical surface is built and numerically solved. Heating of both substrate and the powder material to be deposited on its surface is realized by laser beam and preheating inductor. The task represents a hard-coupled electromagnetic-thermal problem with time-varying geometry. Two specific algorithms are developed to incorporate this effect into the model, driven by local distribution of temperature and its gradients. The algorithms are implemented into the COMSOL Multiphysics 5.2 code that is used for numerical computations of the task. The methodology is illustrated with a typical example whose results are discussed.

Magnetic separator having a multilayer matrix, method and apparatus

DOEpatents

Kelland, David R.

1980-01-01

A magnetic separator having multiple staggered layers of porous magnetic material positioned to intercept a fluid stream carrying magnetic particles and so placed that a bypass of each layer is effected as the pores of the layer become filled with material extracted from the fluid stream.

PERFECTLY MATCHED LAYERS FOR ELASTIC WAVES IN CYLINDRICAL AND SPHERICAL COORDINATES. (R825225)

EPA Science Inventory

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

Problems in nonlinear acoustics: Pulsed finite amplitude sound beams, nonlinear acoustic wave propagation in a liquid layer, nonlinear effects in asymmetric cylindrical sound beams, effects of absorption on the interaction of sound beams, and parametric receiving arrays

NASA Astrophysics Data System (ADS)

Hamilton, Mark F.

1990-12-01

This report discusses five projects all of which involve basic theoretical research in nonlinear acoustics: (1) pulsed finite amplitude sound beams are studied with a recently developed time domain computer algorithm that solves the KZK nonlinear parabolic wave equation; (2) nonlinear acoustic wave propagation in a liquid layer is a study of harmonic generation and acoustic soliton information in a liquid between a rigid and a free surface; (3) nonlinear effects in asymmetric cylindrical sound beams is a study of source asymmetries and scattering of sound by sound at high intensity; (4) effects of absorption on the interaction of sound beams is a completed study of the role of absorption in second harmonic generation and scattering of sound by sound; and (5) parametric receiving arrays is a completed study of parametric reception in a reverberant environment.

Gravitational Collapse with Heat Flux and Gravitational Waves

NASA Astrophysics Data System (ADS)

Ahmad, Zahid; Ahmed, Qazi Zahoor; Awan, Abdul Sami

2013-10-01

In this paper, we investigated the cylindrical gravitational collapse with heat flux by considering the appropriate geometry of the interior and exterior spacetimes. For this purpose, we matched collapsing fluid to an exterior containing gravitational waves.The effects of heat flux on gravitational collapse are investigated and matched with the results obtained by Herrera and Santos (Class. Quantum Gravity 22:2407, 2005).

Solar collector with improved thermal concentration

DOEpatents

Barak, Amitzur Z.

1976-01-01

Reduced heat loss from the absorbing surface of the energy receiver of a cylindrical radiant energy collector is achieved by providing individual, insulated, cooling tubes for adjacent parallel longitudinal segments of the receiver. Control means allow fluid for removing heat absorbed by the tubes to flow only in those tubes upon which energy is then being directed by the reflective wall of the collector.

Adjustable Pitot Probe

NASA Technical Reports Server (NTRS)

Ashby, George C., Jr.; Robbins, W. Eugene; Horsley, Lewis A.

1991-01-01

Probe readily positionable in core of uniform flow in hypersonic wind tunnel. Formed of pair of mating cylindrical housings: transducer housing and pitot-tube housing. Pitot tube supported by adjustable wedge fairing attached to top of pitot-tube housing with semicircular foot. Probe adjusted both radially and circumferentially. In addition, pressure-sensing transducer cooled internally by water or other cooling fluid passing through annulus of cooling system.

Fluid-structure interaction for nonlinear response of shells conveying pulsatile flow

NASA Astrophysics Data System (ADS)

Tubaldi, Eleonora; Amabili, Marco; Païdoussis, Michael P.

2016-06-01

Circular cylindrical shells with flexible boundary conditions conveying pulsatile flow and subjected to pulsatile pressure are investigated. The equations of motion are obtained based on the nonlinear Novozhilov shell theory via Lagrangian approach. The flow is set in motion by a pulsatile pressure gradient. The fluid is modeled as a Newtonian pulsatile flow and it is formulated using a hybrid model that contains the unsteady effects obtained from the linear potential flow theory and the pulsatile viscous effects obtained from the unsteady time-averaged Navier-Stokes equations. A numerical bifurcation analysis employs a refined reduced order model to investigate the dynamic behavior. The case of shells containing quiescent fluid subjected to the action of a pulsatile transmural pressure is also addressed. Geometrically nonlinear vibration response to pulsatile flow and transmural pressure are here presented via frequency-response curves and time histories. The vibrations involving both a driven mode and a companion mode, which appear due to the axial symmetry, are also investigated. This theoretical framework represents a pioneering study that could be of great interest for biomedical applications. In particular, in the future, a more refined model of the one here presented will possibly be applied to reproduce the dynamic behavior of vascular prostheses used for repairing and replacing damaged and diseased thoracic aorta in cases of aneurysm, dissection or coarctation. For this purpose, a pulsatile time-dependent blood flow model is here considered by applying physiological waveforms of velocity and pressure during the heart beating period. This study provides, for the first time in literature, a fully coupled fluid-structure interaction model with deep insights in the nonlinear vibrations of circular cylindrical shells subjected to pulsatile pressure and pulsatile flow.

CFD-DEM Onset of Motion Analysis for Application to Bed Scour Risk Assessment

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

Sitek, M. A.; Lottes, S. A.

This CFD study with DEM was done as a part of the Federal Highway Administration’s (FHWA’s) effort to improve scour design procedures. The Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) model, available in CD-Adapco’s StarCCM+ software, was used to simulate multiphase systems, mainly those which combine fluids and solids. In this method the motion of discrete solids is accounted for by DEM, which applies Newton's laws of motion to every particle. The flow of the fluid is determined by the local averaged Navier–Stokes equations that can be solved using the traditional CFD approach. The interactions between the fluid phase and solidsmore » phase are modeled by use of Newton's third law. The inter-particle contact forces are included in the equations of motion. Soft-particle formulation is used, which allows particles to overlap. In this study DEM was used to model separate sediment grains and spherical particles laying on the bed with the aim to analyze their movement due to flow conditions. Critical shear stress causing the incipient movement of the sediment was established and compared to the available experimental data. An example of scour around a cylindrical pier is considered. Various depths of the scoured bed and flow conditions were taken into account to gain a better understanding of the erosion forces existing around bridge foundations. The decay of these forces with increasing scour depth was quantified with a ‘decay function’, which shows that particles become increasingly less likely to be set in motion by flow forces as a scour hole increases in depth. Computational and experimental examples of the scoured bed around a cylindrical pier are presented.« less

Numerical, Analytical, Experimental Study of Fluid Dynamic Forces in Seals Volume 6: Description of Scientific CFD Code SCISEAL

NASA Technical Reports Server (NTRS)

Athavale, Mahesh; Przekwas, Andrzej

2004-01-01

The objectives of the program were to develop computational fluid dynamics (CFD) codes and simpler industrial codes for analyzing and designing advanced seals for air-breathing and space propulsion engines. The CFD code SCISEAL is capable of producing full three-dimensional flow field information for a variety of cylindrical configurations. An implicit multidomain capability allow the division of complex flow domains to allow optimum use of computational cells. SCISEAL also has the unique capability to produce cross-coupled stiffness and damping coefficients for rotordynamic computations. The industrial codes consist of a series of separate stand-alone modules designed for expeditious parametric analyses and optimization of a wide variety of cylindrical and face seals. Coupled through a Knowledge-Based System (KBS) that provides a user-friendly Graphical User Interface (GUI), the industrial codes are PC based using an OS/2 operating system. These codes were designed to treat film seals where a clearance exists between the rotating and stationary components. Leakage is inhibited by surface roughness, small but stiff clearance films, and viscous pumping devices. The codes have demonstrated to be a valuable resource for seal development of future air-breathing and space propulsion engines.

All-Dielectric Multilayer Cylindrical Structures for Invisibility Cloaking

PubMed Central

Mirzaei, Ali; Miroshnichenko, Andrey E.; Shadrivov, Ilya V.; Kivshar, Yuri S.

2015-01-01

We study optical response of all-dielectric multilayer structures and demonstrate that the total scattering of such structures can be suppressed leading to optimal invisibility cloaking. We use experimental material data and a genetic algorithm to reduce the total scattering by adjusting the material and thickness of various layers for several types of dielectric cores at telecommunication wavelengths. Our approach demonstrates 80-fold suppression of the total scattering cross-section by employing just a few dielectric layers. PMID:25858295

Human Intestinal Fluid Layer Separation: The Effect On Colloidal Structures & Solubility Of Lipophilic Compounds.

PubMed

Danny, Riethorst; Amitava, Mitra; Filippos, Kesisoglou; Wei, Xu; Jan, Tack; Joachim, Brouwers; Patrick, Augustijns

2018-05-23

In addition to individual intestinal fluid components, colloidal structures are responsible for enhancing the solubility of lipophilic compounds. The present study investigated the link between as well as the variability in the ultrastructure of fed state human intestinal fluids (FeHIF) and their solubilizing capacity for lipophilic compounds. For this purpose, FeHIF samples from 10 healthy volunteers with known composition and ultrastructure were used to determine the solubility of four lipophilic compounds. In light of the focus on solubility and ultrastructure, the study carefully considered the methodology of solubility determination in relation to colloid composition and solubilizing capacity of FeHIF. To determine the solubilizing capacity of human and simulated intestinal fluids, the samples were saturated with the compound of interest, shaken for 24 h, and centrifuged. When using FeHIF, solubilities were determined in the micellar layer of FeHIF, i.e. after removing the upper (lipid) layer (standard procedure), as well as in 'full' FeHIF (without removal of the upper layer). Compound concentrations were determined using HPLC-UV/fluorescence. To link the solubilizing capacity with the ultrastructure, all human and simulated fluids were imaged using transmission electron microscopy (TEM) before and after centrifugation and top layer (lipid) removal. Comparing the ultrastructure and solubilizing capacity of individual FeHIF samples demonstrated a high intersubject variability in postprandial intestinal conditions. Imaging of FeHIF after removal of the upper layer clearly showed that only micellar structures remain in the lower layer. This observation suggests that larger colloids such as vesicles and lipid droplets are contained in the upper, lipid layer. The solubilizing capacity of most FeHIF samples substantially increased with inclusion of this lipid layer. The relative increase in solubilizing capacity upon inclusion of the lipid layer was most pronounced in samples that contained mainly vesicles alongside the micelles. Current fed state simulated intestinal fluids do not contain the larger colloids observed in the lipid layer of FeHIF and can only simulate the solubilizing capacity of the micellar layer of FeHIF. While the importance of drug molecules solubilized in the micellar layer of postprandial intestinal fluids for absorption has been extensively demonstrated previously, the in-vivo relevance of drug solubilization in the lipid layer is currently unclear. In the dynamic environment of the human gastrointestinal tract, drug initially entrapped in larger postprandial colloids may become available for absorption upon lipid digestion and uptake. The current study, demonstrating the substantial solubilization of lipophilic compounds in the larger colloids of postprandial intestinal fluids, warrants further research in this field. Copyright © 2018. Published by Elsevier B.V.

The extensional rheology of non-Newtonian materials

NASA Technical Reports Server (NTRS)

Spiegelberg, Stephen H.; Gaudet, Samuel; Mckinley, Gareth H.

1994-01-01

It has been proposed to measure the extensional viscosity function of a non-Newtonian polymer solution in a reduced gravity environment as part of the Advanced Fluid Module. In ground-based extensional measurements, the no-sip boundary condition at solid-fluid interfaces always result in appreciable shear gradients in the test fluid; however the removal of gravitational body forces permits controlled extensional deformation of containerless test samples and the first unambiguous measurements of this kind. Imperative to successful implementation of this experiment is the generation and subsequent deformation of a stable cylindrical column of test fluid. A study of the generation and deformation of liquid bridges demonstrates that Newtonian liquid bridges undergo capillary breakup as anticipated when stretched beyond a critical aspect ratio; non-Newtonian liquid bridges, however, are stabilized by the strain-hardening phenomenon exhibited by these materials. Numerical simulations of Newtonian breakup are compared with experimental results, and show that previous ground-based attempts at measuring the extensional viscosity of Newtonian fluids are of limited accuracy.

Propagating plane harmonic waves through finite length plates of variable thickness using finite element techniques

NASA Technical Reports Server (NTRS)

Clark, J. H.; Kalinowski, A. J.; Wagner, C. A.

1983-01-01

An analysis is given using finite element techniques which addresses the propagaton of a uniform incident pressure wave through a finite diameter axisymmetric tapered plate immersed in a fluid. The approach utilized in developing a finite element solution to this problem is based upon a technique for axisymmetric fluid structure interaction problems. The problem addressed is that of a 10 inch diameter axisymmetric fixed plate totally immersed in a fluid. The plate increases in thickness from approximately 0.01 inches thick at the center to 0.421 inches thick at a radius of 5 inches. Against each face of the tapered plate a cylindrical fluid volume was represented extending five wavelengths off the plate in the axial direction. The outer boundary of the fluid and plate regions were represented as a rigid encasement cylinder as was nearly the case in the physical problem. The primary objective of the analysis is to determine the form of the transmitted pressure distribution on the downstream side of the plate.

Effect of Prestresses on the Dispersion of Quasi-Lamb Waves in the System Consisting of an Ideal Liquid Layer and a Compressible Elastic Layer

NASA Astrophysics Data System (ADS)

Bagno, A. M.

2017-03-01

The propagation of quasi-Lamb waves in a prestrained compressible elastic layer interacting with a layer of an ideal compressible fluid is studied. The three-dimensional equations of linearized elasticity and the assumption of finite strains for the elastic layer and the three-dimensional linearized Euler equations for the fluid are used. The dispersion curves for the quasi-Lamb modes are plotted over a wide frequency range. The effect of prestresses and the thickness of the elastic and liquid layers on the frequency spectrum of normal quasi-Lamb waves is analyzed. The localization properties of the lower quasi-Lamb modes in the elastic-fluid waveguides are studied. The numerical results are presented in the form of graphs and analyzed

Laboratory layered latte.

PubMed

Xue, Nan; Khodaparast, Sepideh; Zhu, Lailai; Nunes, Janine K; Kim, Hyoungsoo; Stone, Howard A

2017-12-12

Inducing thermal gradients in fluid systems with initial, well-defined density gradients results in the formation of distinct layered patterns, such as those observed in the ocean due to double-diffusive convection. In contrast, layered composite fluids are sometimes observed in confined systems of rather chaotic initial states, for example, lattes formed by pouring espresso into a glass of warm milk. Here, we report controlled experiments injecting a fluid into a miscible phase and show that, above a critical injection velocity, layering emerges over a time scale of minutes. We identify critical conditions to produce the layering, and relate the results quantitatively to double-diffusive convection. Based on this understanding, we show how to employ this single-step process to produce layered structures in soft materials, where the local elastic properties vary step-wise along the length of the material.

Initial decay of flow properties of planar, cylindrical and spherical blast waves

NASA Astrophysics Data System (ADS)

Sadek, H. S. I.; Gottlieb, J. J.

1983-10-01

Analytical expressions are presented for the initial decay of all major flow properties just behind planar, cylindrical, and spherical shock wave fronts whose trajectories are known as a function of either distance versus time or shock overpressure versus distance. These expressions give the time and/or distance derivatives of the flow properties not only along constant time and distance lines but also along positive and negative characteristic lines and a fluid-particle path. Conventional continuity, momentum and energy equations for the nonstationary motion of an inviscid, non-heat conducting, compressible gas are used in their derivation, along with the equation of state of a perfect gas. All analytical expressions are validated by comparing the results to those obtained indirectly from known self-similar solutions for planar, cylindrical and spherical shock-wave flows generated both by a sudden energy release and by a moving piston. Futhermore, time derivatives of pressure and flow velocity are compared to experimental data from trinitrotoluene (TNT), pentolite, ammonium nitrate-fuel oil (ANFO) and propane-oxygen explosions, and good agreement is obtained.

Stochastic Evolution of Augmented Born-Infeld Equations

NASA Astrophysics Data System (ADS)

Holm, Darryl D.

2018-06-01

This paper compares the results of applying a recently developed method of stochastic uncertainty quantification designed for fluid dynamics to the Born-Infeld model of nonlinear electromagnetism. The similarities in the results are striking. Namely, the introduction of Stratonovich cylindrical noise into each of their Hamiltonian formulations introduces stochastic Lie transport into their dynamics in the same form for both theories. Moreover, the resulting stochastic partial differential equations retain their unperturbed form, except for an additional term representing induced Lie transport by the set of divergence-free vector fields associated with the spatial correlations of the cylindrical noise. The explanation for this remarkable similarity lies in the method of construction of the Hamiltonian for the Stratonovich stochastic contribution to the motion in both cases, which is done via pairing spatial correlation eigenvectors for cylindrical noise with the momentum map for the deterministic motion. This momentum map is responsible for the well-known analogy between hydrodynamics and electromagnetism. The momentum map for the Maxwell and Born-Infeld theories of electromagnetism treated here is the 1-form density known as the Poynting vector. Two appendices treat the Hamiltonian structures underlying these results.

Ceramic turbine stator vane and shroud support

DOEpatents

Glenn, Robert G.

1981-01-01

A support system for supporting the stationary ceramic vanes and ceramic outer shrouds which define the motive fluid gas path in a gas turbine engine is shown. Each individual segment of the ceramic component whether a vane or shroud segment has an integral radially outwardly projecting stem portion. The stem is enclosed in a split collet member of a high-temperature alloy material having a cavity configured to interlock with the stem portion. The generally cylindrical external surface of the collet engages a mating internal cylindrical surface of an aperture through a supporting arcuate ring segment with mating camming surfaces on the two facing cylindrical surfaces such that radially outward movement of the collet relative to the ring causes the internal cavity of the collet to be reduced in diameter to tightly engage the ceramic stem disposed therein. A portion of the collet extends outwardly through the ring segment opposite the ceramic piece and is threaded for receiving a nut and a compression washer for retaining the collet in the ring segment under a continuous biasing force urging the collet radially outwardly.

Cylindrical fast magnetosonic solitary waves in quantum degenerate electron-positron-ion plasma

NASA Astrophysics Data System (ADS)

Abdikian, A.

2018-02-01

The nonlinear properties of fast magnetosonic solitary waves in a quantum degenerate electron-positron (e-p) plasma in the presence of stationary ions for neutralizing the plasma background of bounded cylindrical geometry were studied. By employing the standard reductive perturbation technique and the quantum hydrodynamic model for the e-p fluid, the cylindrical Kadomtsev-Petviashvili (CKP) equation was derived for small, but finite, amplitude waves and was given the solitary wave solution for the parameters relevant to dense astrophysical objects such as white dwarf stars. By a suitable coordinate transformation, the CKP equation can be solved analytically. An analytical solution for magnetosonic solitons and periodic waves is presented. The numerical results reveal that the Bohm potential has a main effect on the periodic and solitary wave structures. By increasing the values of the plasma parameters, the amplitude of the solitary wave will be increased. The present study may be helpful in the understanding of nonlinear electromagnetic soliton waves propagating in both laboratory and astrophysical plasmas, and can help in providing good agreement between theoretical results and laboratory plasma experiments.

Boattail juncture shaping for spin-stabilized rounds in supersonic flight

NASA Astrophysics Data System (ADS)

Jiajan, W.; Chue, R. S. M.; Nguyen, T.; Yu, S. C. M.

2015-03-01

In this paper, the effects of boattail junction shaping on aerodynamic drag and stability of supersonic spin-stabilized rounds are investigated using computational fluid dynamics. For a generic round body comprising of a secant-ogive nose, a cylindrical body and a conical boattail, the shaping technique was achieved by adding a convex surface of varying degrees of radius of curvature to the junction between the cylindrical body and the boattail. It was shown through numerical simulations that this shaping technique can provide a reduction in aerodynamic drag of up to 5.4 % without destabilizing the round bodies when the radius of curvature is less than 8.8 times the diameter of the cylindrical body. The more gradual change of the flow characteristics, e.g., the pressure over the convex surface, was identified as the main reason for the drag reduction. A unique aspect of the current work is that stability is treated as an integral part of the performance assessment. It was also found that the dynamic instability encountered at large radii of curvature is due to the Magnus effects.

Thin film instabilities: Rayleigh-Taylor with thermocapillarity and Kolmogorov flow in a soap film

NASA Astrophysics Data System (ADS)

Burgess, John Matthew

The Rayleigh-Taylor instability occurs when a more dense fluid layer is suspended above a less dense fluid layer in a gravitational field. The horizontal interface between the two fluids is unstable to infinitesimal deformations and the dense fluid falls. To counteract the destabilizing effects of gravity on the interface between two thin fluid layers, we apply a vertical temperature gradient, heating from below. The dependence of surface tension on temperature (``thermocapillarity'') can cause spatially-varying interfacial forces between two immiscible fluid layers if a variation in temperature along the interface is introduced. With an applied vertical temperature gradient, the deforming interface spontaneously develops temperature variations which locally adjust the surface tension to restore a flat interface. We find that these surface tension gradients can stabilize a more dense thin fluid layer (silicone oil, 0.015 cm thick) above a less dense thin fluid layer (air, 0.025 cm thick) in a gravitational field, in qualitative agreement with linear stability analysis. This is the first experimental observation of the stabilization of Rayleigh-Taylor instability by thermocapillary forces. We also examine the instability of a soap film flow driven by a time-independent force that is spatially periodic in the direction perpendicular to the forcing (Kolmogorov flow). The film is in the x- y plane, where the forcing approximates a shape sin (y)x̂. Linear stability analysis of an idealized model of this flow predicts a critical Reynolds number Rc~2 . In our soap film experiment, we find a critical value Rc~70 . This discrepancy can be ascribed to frictional effects from viscous coupling of gas to the film, which is neglected in the idealized model. The kinematic viscosity of the surrounding gas and the thickness of gas layers on each side of the soap film are varied in the experiments to better understand these frictional effects. We conclude that flows in soap films cannot be decoupled from flows in the surrounding gas.

Effects of the heat transfer fluid velocity on the storage characteristics of a cylindrical latent heat energy storage system: a numerical study

NASA Astrophysics Data System (ADS)

Ogoh, Wilson; Groulx, Dominic

2012-03-01

A numerical study of the effects of the thermal fluid velocity on the storage characteristics of a cylindrical latent heat energy storage system (LHESS) was conducted. Due to the low thermal conductivity of phase change materials (PCMs) used in LHESS, fins were added to the system to increase the rate of heat transfer and charging. Finite elements were used to implement the developed numerical method needed to study and solve for the phase change heat transfer (melting of PCM) encountered in a LHESS during charging. The effective heat capacity method was applied in order to account for the large amount of latent energy stored during melting of the PCM and the moving interface between the solid and liquid phases. The effects of the heat transfer fluid (HTF) velocity on the melting rate of the PCM were studied for configurations having between 0 and 18 fins. Results show that the overall heat transfer rate to the PCM increases with an increase in the HTF velocity. However, the effect of the HTF velocity was observed to be small in configurations having very few fins, owing to the large residual thermal resistance offered by the PCM. However, the effect of the HTF velocity becomes more pronounced with addition of fins; since the thermal resistance on the PCM side of the LHESS is significantly reduce by the large number of fins in the system.

Synchronism of nonlinear internal waves in a three-layer fluid

NASA Astrophysics Data System (ADS)

Talipova, Tatiana; Kurkina, Oxana; Terletska, Katerina; Rouvinskaya, Ekaterina

2017-04-01

In a three layer fluid with arbitrary layer widths and densities the existence of long internal solitons and breathers is proven theoretically and numerically, see for example (Pelinovsky et al., 2007; Lamb et al., 2007). The existence of breather-like waves of the intermediate length is also shown in numerical simulations (Terletska et al., 2016). For such waves conditions of synchronism are valid when a breather of the first mode and a soliton of the second mode move together with the same speed and form an asymmetric solitary wave of the second mode. The process of strong interaction of long nonlinear internal waves in the framework of three-layer Camassa-Choi model demonstrates the same effect (Jo&Choi, 2014; Barros, 2016). We analyze possible synchronism conditions for steady-state internal waves in a three-layer fluid analytically the framework of the Gardner equation, which is valid for long weakly nonlinear internal waves. The equations for synchronism conditions are derived and considered in terms of wave amplitudes, layer widths and density jumps. The configurations of three-layer fluid are found for which such a synchronism is possible. References: Barros R. Large amplitude internal waves in three-layer flows. The forth international conference "Nonlinear Waves - Theory and Applications", MS7, Beijing, China, June 25 - 28, 2016 Pelinovsky E., Polukhina O., Slunyaev A., Talipova T. Internal solitary waves // Chapter 4 in the book "Solitary Waves in Fluids". WIT Press. Southampton, Boston. 2007. P. 85 - 110. K. Terletska., K. T. Jung, T. Talipova, V. Maderich, I. Brovchenko and R. Grimshaw Internal breather-like wave generation by the second mode solitary wave interaction with a step// Physics of Fluids, 2016, accepted

Turbulent entrainment across turbulent-nonturbulent interfaces in stably stratified mixing layers

NASA Astrophysics Data System (ADS)

Watanabe, T.; Riley, J. J.; Nagata, K.

2017-10-01

The entrainment process in stably stratified mixing layers is studied in relation to the turbulent-nonturbulent interface (TNTI) using direct numerical simulations. The statistics are calculated with the interface coordinate in an Eulerian frame as well as with the Lagrangian fluid particles entrained from the nonturbulent to the turbulent regions. The characteristics of entrainment change as the buoyancy Reynolds number Reb decreases and the flow begins to layer. The baroclinic torque delays the enstrophy growth of the entrained fluids at small Reb, while this effect is less efficient for large Reb. The entrained particle movement within the TNTI layer is dominated by the small dissipative scales, and the rapid decay of the kinetic energy dissipation rate due to buoyancy causes the entrained particle movement relative to the interface location to become slower. Although the Eulerian statistics confirm that there exists turbulent fluid with strong vorticity or with large buoyancy frequency near the TNTI, the entrained fluid particles circumvent these regions by passing through the TNTI in strain-dominant regions or in regions with small buoyancy frequency. The multiparticle statistics show that once the nonturbulent fluid volumes are entrained, they are deformed into flattened shapes in the vertical direction and diffuse in the horizontal direction. When Reb is large enough for small-scale turbulence to exist, the entrained fluid is able to penetrate into the turbulent core region. Once the flow begins to layer with decreasing Reb, however, the entrained fluid volume remains near the outer edge of the turbulent region and forms a stably stratified layer without vertical overturning.

Models for the dynamics of dust-like matter in the self-gravity field: The method of hydrodynamic substitutions

NASA Astrophysics Data System (ADS)

Zhuravlev, V. M.

2017-09-01

Models for the dynamics of a dust-like medium in the self-gravity field are investigated. Solutions of the corresponding problems are constructed by the method of hydrodynamic substitutions generalizing the Cole-Hopf substitutions. The method is extended to multidimensional ideal and viscous fluid flows with cylindrical and spherical symmetries for which exact solutions are constructed. Solutions for the dynamics of self-gravitating dust with arbitrary initial distributions of both fluid density and velocity are constructed using special coordinate transformations. In particular, the problem of cosmological expansion is considered in terms of Newton's gravity theory. Models of a one-dimensional viscous dust fluid flow and some problems of gas hydrodynamics are considered. Examples of exact solutions and their brief analysis are provided.

Fabrication of cylindrical superhydrophobic microchannels by replicating lotus leaf structures on internal walls

NASA Astrophysics Data System (ADS)

Das, Ajit; Bhaumik, Soubhik Kumar

2018-04-01

Cylindrical superhydrophobic microchannels are fabricated by replicating lotus leaf structures on internal walls. The fabrication process comprises of three steps: the creation of a cylindrical mold of a glass rod (125 µm) with polystyrene films bearing negative imprints of lotus leaf (superhydrophobic) structures; casting polydimethylsiloxane (PDMS, Sylgard 184) over the mold; and solvent-assisted pulling off of the glass rod to leave a positive replica on the inner wall of the PDMS cast. The last crucial step is achieved through selective dissolution of the intermediate negative replica layer in the cylindrical mold without any swelling effect. The high fidelity of the replication process is confirmed through scanning electron microscope (SEM) imaging. The attained superhydrophobicity is assessed by comparing the dynamics of the advancing meniscus in the fabricated microchannels with that over a similarly fabricated smooth microchannel. Contact angle studies of the meniscus reveal a lower capillary effect and drag force experienced by the superhydrophobic microchannel compared to smooth ones. Studies based on velocity lead to a prediction of a drag reduction of 35%. A new avenue is thus opened up for microfabrication and flow analysis of closed superhydrophobic (SH) conduits in lab on chip and microfluidic applications.

Contoured tank outlets for draining of cylindrical tanks in low-gravity environment. [Lewis Research Center Zero Gravity Facility

NASA Technical Reports Server (NTRS)

Symons, E. P.

1979-01-01

An analysis is presented for defining the outlet contour of a hemispherical-bottomed cylindrical tank that will prevent vapor ingestion when the tank is drained. The analysis was used to design two small-scale tanks that were fabricated and then tested in a low gravity environment. The draining performance of the tanks was compared with that for a tank with a conventional outlet having a constant circular cross-sectional area, under identical conditions. Even when drained at off-design conditions, the contoured tank had less liquid residuals at vapor ingestion than the conventional outlet tank. Effects of outflow rate, gravitational environment, and fluid properties on the outlet contour are discussed. Two potential applications of outlet contouring are also presented and discussed.

An experimental study of oscillatory thermocapillary convection in cylindrical containers

NASA Technical Reports Server (NTRS)

Kamotani, Y.; Lee, J. H.; Ostrach, S.; Pline, A.

1992-01-01

An experimental study of oscillatory thermocapillary in small cylindrical containers with a heating wire placed along the center axis is performed by investigating the flow structures and temperature distributions under various conditions. To supplement the flow visualization the surface is scanned using an infrared imager. Here, 2 cS viscosity (Pr = 27) silicone oil is used as the test fluid. It is observed that beyond a certain temperature difference between the container wall and the heating wire, a distinctive unsteady flow pattern appears. This unsteady phenomenon is identified as oscillatory thermocapillary. After the onset of oscillations the flow structure becomes nonaxisymmetric and wave motion is observed at the free surface. It is shown that the critical temperature difference is independent of container dimensions if the aspect ratio is fixed.

Nonlinear nature of composite structure induced by the interaction of nonplanar solitons in a nonextensive plasma

NASA Astrophysics Data System (ADS)

Han, Jiu-Ning; Luo, Jun-Hua; Liu, Zhen-Lai; Shi, Jun; Xiang, Gen-Xiang; Li, Jun-Xiu

2015-06-01

The nonlinear properties of composite structure induced by the head-on collision of electron-acoustic solitons in a general plasma composed of cold fluid electrons, hot nonextensive distributed electron, and stationary ions are studied. We have made a detailed investigation on the time-evolution process of this merged wave structure. It is found that the structure survives during some time interval, and there are obviously different for the properties of the composite structures which are induced in cylindrical and spherical geometries. Moreover, it is shown that there are both positive and negative phase shifts for each colliding soliton after the interaction. For fixed plasma parameters, the soliton received the largest phase shift in spherical geometry, followed by the cylindrical and one-dimensional planar geometries.

Platinum Electrodeposition for Supported ALD Templated Foam Hohlraum Liners

DOE PAGES

Horwood, Corie; Stadermann, Michael; Biener, Monika; ...

2017-12-20

Two commercially available platinum plating solutions (Platanex III and Platanex Luna) were evaluated for the electrodeposition of platinum layers on gold hohlraums and cylindrically shaped silver-gold ingots. The successful deposition of thin Pt layers on gold hohlraums as well as thick Pt layers on silver-gold alloys will allow for the integration of atomic layer deposition templated foam inside a hohlraum. We found that when the manufacturer’s recommendations for the Pt plating solutions were used, the coatings obtained were unacceptable because of cracking, poor adhesion, or thin and powdery Pt deposits. Therefore, alternative plating parameters were investigated, and the conditions resultingmore » in acceptable coatings are reported here.« less

Platinum Electrodeposition for Supported ALD Templated Foam Hohlraum Liners

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

Horwood, Corie; Stadermann, Michael; Biener, Monika

Two commercially available platinum plating solutions (Platanex III and Platanex Luna) were evaluated for the electrodeposition of platinum layers on gold hohlraums and cylindrically shaped silver-gold ingots. The successful deposition of thin Pt layers on gold hohlraums as well as thick Pt layers on silver-gold alloys will allow for the integration of atomic layer deposition templated foam inside a hohlraum. We found that when the manufacturer’s recommendations for the Pt plating solutions were used, the coatings obtained were unacceptable because of cracking, poor adhesion, or thin and powdery Pt deposits. Therefore, alternative plating parameters were investigated, and the conditions resultingmore » in acceptable coatings are reported here.« less

Coolant side heat transfer with rotation: User manual for 3D-TEACH with rotation

NASA Technical Reports Server (NTRS)

Syed, S. A.; James, R. H.

1989-01-01

This program solves the governing transport equations in Reynolds average form for the flow of a 3-D, steady state, viscous, heat conducting, multiple species, single phase, Newtonian fluid with combustion. The governing partial differential equations are solved in physical variables in either a Cartesian or cylindrical coordinate system. The effects of rotation on the momentum and enthalpy calculations modeled in Cartesian coordinates are examined. The flow of the fluid should be confined and subsonic with a maximum Mach number no larger than 0.5. This manual describes the operating procedures and input details for executing a 3D-TEACH computation.

Geometric situation of points of division of regions of direct and return currency in channels with the presence of heating zone limited on the longitudinal coordinate

NASA Astrophysics Data System (ADS)

Gerasimov, A.; Kirpichnikov, A.; Sabirova, F.

2018-03-01

The analysis of energy balance equation for viscous laminar flow of fluid or gas in the cylindrical channel in the area (zone) of warm up bounded along the longitudinal coordinate is made. It was found that at laminar flow of fluid or gas in a round pipe, in each warm up area bounded along the longitudinal coordinate there are the areas of direct and reverse flows separated by a plane that is a locus of points where temperature is maximal for each fixed value of radial coordinate r.

Theoretical regime diagrams for thermally driven flows in a beta-plane channel. [in atmosphere

NASA Technical Reports Server (NTRS)

Geisler, J. E.; Fowlis, W. W.

1979-01-01

It is noted that thermally driven flows in rotating laboratory containers with cylindrical geometry can be axially symmetric or wavelike depending on the experimental parameters. In anticipation that rotating fluid experiments might soon be done in spherical shell geometry, Barcilon's model has been extended to a beta-plane channel in order to gain a rough understanding of the effects of rotating spherical geometry. An incompressible fluid version of the Charney (1947) model of baroclinic instability, modified to include Ekman pumping at rigid horizontal boundaries is used. With this model, stability boundaries are mapped out for individual zonal wavenumbers in the parameter space used by Barcilon.

NEUTRONIC REACTOR

DOEpatents

Daniels, F.

1962-12-18

A power plant is described comprising a turbine and employing round cylindrical fuel rods formed of BeO and UO/sub 2/ and stacks of hexagonal moderator blocks of BeO provided with passages that loosely receive the fuel rods so that coolant may flow through the passages over the fuels to remove heat. The coolant may be helium or steam and fiows through at least one more heat exchanger for producing vapor from a body of fluid separate from the coolant, which fluid is to drive the turbine for generating electricity. By this arrangement the turbine and directly associated parts are free of particles and radiations emanating from the reactor. (AEC)

Convection induced by selective absorption of radiation: A laboratory model of conditional instability

NASA Astrophysics Data System (ADS)

Krishnamurti, Ruby

1998-01-01

When there is internal heating in a fluid layer, convection can occur even if the static state is one of stable stratification. We have been investigating through laboratory experiments such a stably stratified layer of water which is heated above and cooled below. The water contains in dilute solution thymol blue (a pH indicator), which normally colors the water orange. It turns yellow if the pH is low, blue if the pH is high. A small DC voltage is applied across the layer, by using the bottom boundary as the positive electrode, the top boundary as the negative electrode. The hydroxyl ions formed near the bottom boundary cause the orange fluid to turn blue. The fluid layer is uniformly and steadily illuminated from above with light from a sodium vapor lamp. This radiation travels with negligible absorption through the orange fluid but is strongly absorbed by the blue fluid. The resultant warming of the blue fluid can lead to convective instability, with the blue fluid rising into warm upper layers, which it would continue to penetrate as long as it remains blue and as long as the radiative heating is sufficient to exceed the higher ambient temperatures above. This radiative heating occurs only in the blue rising flow; the sinking fluid is orange and is not heated. We have found that with a strongly stably stratified layer, convective plumes are unable to penetrate far and they remain shallow. However, for a weakly stratified layer, plumes grow tall and furthermore collect into a large convective cluster which persists as a steady coherent structure. The present paper deals also with the formulation of the governing equations to include the fluid-state-dependent heat source. A linear stability analysis shows that the critical Rayleigh number for onset of motion is drastically reduced. Furthermore, the cell size at onset is larger by a factor of √ 3/2 than in the classical Rayleigh-Benard convection problem. However, the laboratory fluid cells were much further broadened (by a factor of 8 or 10) when they penetrated into the stably stratified fluid above. In this case, the rising region is narrow and the sinking region is broad, so that downward vertical velocities are correspondingly small. In this way, the downwards-forced warm fluid has time to cool by conduction to the cold boundary. Steady finite amplitude solutions and their stability are analyzed and it is shown that there is a parameter range in which finite amplitude hexagonal cells are stable.

Density Relaxation of Liquid-Vapor Critical Fluids Examined in Earth's Gravity

NASA Technical Reports Server (NTRS)

Wilkinson, R. Allen

2000-01-01

This work shows quantitatively the pronounced differences between the density equilibration of very compressible dense fluids in Earth's gravity and those in microgravity. The work was performed onsite at the NASA Glenn Research Center at Lewis Field and is complete. Full details are given in references 1 and 2. Liquid-vapor critical fluids (e.g., water) at their critical temperature and pressure, are very compressible. They collapse under their own weight in Earth's gravity, allowing only a thin meniscus-like layer with the critical pressure to survive. This critical layer, however, greatly slows down the equilibration process of the entire sample. A complicating feature is the buoyancy-driven slow flows of layers of heavier and lighter fluid. This work highlights the incomplete understanding of the hydrodynamics involved in these fluids.

Calculation of nanodrop profile from fluid density distribution.

PubMed

Berim, Gersh O; Ruckenstein, Eli

2016-05-01

Two approaches are examined, which can be used to determine the drop profile from the fluid density distributions (FDDs) obtained on the basis of microscopic theories. For simplicity, only two-dimensional (cylindrical, or axisymmetrical) distributions are examined and it is assumed that the fluid is either in contact with a smooth solid or separated from the smooth solid by a lubricating liquid film. The first approach is based on the sharp-kink interface approximation in which the density of the liquid inside and the density of the vapor outside the drop are constant with the exception of the surface layer of the drop where the density is different from the above ones. In this case, the drop profile was calculated by minimizing the total potential energy of the system. The second approach is based on a nonuniform FDD obtained either by the density functional theory or molecular dynamics simulations. To determine the drop profile from such an FDD, which does not contain sharp interfaces, three procedures can be used. In the first two procedures, P1 and P2, the one-dimensional FDDs along straight lines which are parallel to the surface of the solid are extracted from the two-dimensional FDD. Each of those one-dimensional FDDs has a vapor-liquid interface at which the fluid density changes from vapor-like to liquid-like values. Procedure P1 uses the locations of the equimolar dividing surfaces for the one-dimensional FDDs as points of the drop profile. Procedure P2 is based on the assumption that the fluid density is constant on the surface of the drop, that density being selected either arbitrarily or as a fluid density at the location of the equimolar dividing surface for one of the one-dimensional FDDs employed in procedure P1. In the third procedure, P3, which is suggested for the first time in this paper, the one-dimensional FDDs are taken along the straight lines passing through a selected point inside the drop (radial line). Then, the drop profile is calculated like in procedure P1. It is shown, that procedure P3 provides a drop profile which is more reasonable than the other ones. Relationship of the discussed procedures to those used in image analysis is briefly discussed. Copyright © 2016 Elsevier B.V. All rights reserved.

Laboratory Layered Latte

NASA Astrophysics Data System (ADS)

Xue, Nan; Khodaparast, Sepideh; Zhu, Lailai; Nunes, Janine; Kim, Hyoungsoo; Stone, Howard

2017-11-01

Layered composite fluids are sometimes observed in confined systems of rather chaotic initial states, for example, layered lattes formed by pouring espresso into a glass of warm milk. In such configurations, pouring forces a lower density liquid (espresso) into a higher density ambient, which is similar to the fountain effects that characterize a wide range of flows driven by injecting a fluid into a second miscible phase. Although the initial state of the mixture is complex and chaotic, there are conditions where the mixture cools at room temperature and exhibits an organized layered pattern. Here we report controlled experiments injecting a fluid into a miscible phase and show that, above a critical injection velocity, layering naturally emerges over the time scale of minutes. We perform experimental and numerical analyses of the time-dependent flows to observe and understand the convective circulation in the layers. We identify critical conditions to produce the layering and relate the results quantitatively to the critical Rayleigh number in double-diffusive convection, which indicates the competition between the horizontal thermal gradient and the vertical density gradient generated by the fluid injection. Based on this understanding, we show how to employ this single-step process to produce layered structures in soft materials, where the local elastic properties as well as the local material concentration vary step-wise along the length of the material.

Inertial wave beams and inertial wave modes in a rotating cylinder with time-modulated rotation rate

NASA Astrophysics Data System (ADS)

Borcia, Ion D.; Ghasemi V., Abouzar; Harlander, Uwe

2014-05-01

Inertial gravity waves play an crucial role in atmospheres, oceans, and the fluid inside of planets and moons. In the atmosphere, the effect of rotation is neglected for small wavelength and the waves bear the character of internal gravity waves. For long waves, the hydrostatic assumption is made which in turn makes the atmosphere inelastic with respect to inertial motion. In contrast, in the Earth's interior, pure inertial waves are considered as an important fundamental part of the motion. Moreover, as the deep ocean is nearly homogeneous, there the inertial gravity waves bear the character of inertial waves. Excited at the oceans surface mainly due to weather systems the waves can propagate downward and influence the deep oceans motion. In the light of the aforesaid it is important to understand better fundamental inertial wave dynamics. We investigate inertial wave modes by experimental and numerical methods. Inertial modes are excited in a fluid filled rotating annulus by modulating the rotation rate of the outer cylinder and the upper and lower lids. This forcing leads to inertial wave beams emitted from the corner regions of the annulus due to periodic motions in the boundary layers (Klein et al., 2013). When the forcing frequency matches with the eigenfrequency of the rotating annulus the beam pattern amplitude is increasing, the beams broaden and mode structures can be observed (Borcia et al., 2013a). The eigenmodes are compared with analytical solutions of the corresponding inviscid problem (Borcia et al, 2013b). In particular for the pressure field a good agreement can be found. However, shear layers related to the excited wave beams are present for all frequencies. This becomes obvious in particular in the experimental visualizations that are done by using Kalliroscope particles, highlighting relative motion in the fluid. Comparing the eigenfrequencies we find that relative to the analytical frequencies, the experimental and numerical ones show a small shift towards higher frequencies. This frequency shift is due to the reduction of the effective resonance volume that results from the existence of a Stokes boundary layer at the outer librating wall. Due to the symmetry of the forcing not all possible modes can be excited. It is shown that only symmetric modes with respect to the rotation axis exist. From a fundamental perspective, the study might help to understand better inertial mode excitation in librating planets and moons where inertial waves are emitted from critical points on the inner or outer spherical boundary. Recently, Zhang et al. (2013) pointed out the resonance should not occur in symmetric librating bodies without precession. We will discuss how this assumption depends on the boundary conditions. It might turn out that even when the projection of the Euler (or Poincare) force on the modes is zero, the projection of the excited wave beams on the modes is non-zero. K. Zhang, K. H. Chan, X. Liao, and J. M. Aurnou. The non-resonant response of fluid in a rapidly rotating sphere undergoing longitudinal libration, J. Fluid Mech.,720, 212-235, 2013. I. D. Borcia and U. Harlander. Inertial waves in a rotating annulus with inclined inner cylinder, Theoret. Comp. Fluid Dynamics, 27, 397-413, 2013. I. D. Borcia, A. Ghasemi V., and U. Harlander. Inertial wave mode excitation inside a rotating cylindrical container with librating walls, submitted to Fluid Dyn. Res.,2013. M. Klein, T. Seelig, M. V. Kurgansky, A. Ghasemi V., I. D. Borcia, A. Will, E. Schaller, C. Egbers, and Uwe Harlander. Inertial wave excitation and focusing in a liquid bounded by a frustum and a cylinder, submitted to J. Fluid Mech., 2013.

Investigating the Stability of a Bottle Filled with Different Amounts of Fluid

ERIC Educational Resources Information Center

Pahwa, Gantavya; Pingali, Rushil G.; Khubchandani, Aashish K.; Roy, Ekansh; Mudaliyar, Roshni R.; Mudaliyar, Rajesh P.

2017-01-01

The aim of this paper is to investigate the stability of a bottle filled with different volumes of water, and to determine the angle at which it topples over for each volume of water. Data for the angle at which the bottle toppled were gathered experimentally using a cylindrical 1 litre bottle, and two theoretical models were then developed,…

Analysis of electrophoresis performance

NASA Technical Reports Server (NTRS)

Roberts, Glyn O.

1988-01-01

A flexible efficient computer code is being developed to simulate electrophoretic separation phenomena, in either a cylindrical or a rectangular geometry. The code will computer the evolution in time of the concentrations of an arbitrary number of chemical species, and of the temperature, pH distribution, conductivity, electric field, and fluid motion. Use of nonuniform meshes and fast accurate implicit time-stepping will yield accurate answers at economical cost.

76 FR 78698 - Proposed Revocation of Permanent Variances

Federal Register 2010, 2011, 2012, 2013, 2014

2011-12-19

... cylindrical steel tanks. Construction of these tanks involves attaching curved steel plates together to form the outer surface of a tank. After attaching a horizontal layer (ring) of steel plates around the circumference of the existing shell, employees raise the scaffolds to attach the next ring of steel plates onto...

Micromechanical measurement of wood substructure properties.

Treesearch

David E. Kretschmann; Troy W. Schmidt; Roderic S. Lakes; Steven M. Cramer

2002-01-01

The annual rings of softwoods are visually obvious and represent cylindrical layers of primarily cellulosic material that possess significantly different properties. For simplicity, wood construction products are designed assuming a material homogeneity that does not exist. As rapidly grown plantation trees are used for wood products, fewer rings are contained in an...

High-Aspect-Ratio Rotating Cell-Culture Vessel

NASA Technical Reports Server (NTRS)

Wolf, David A.; Sams, Clarence; Schwarz, Ray P.

1992-01-01

Cylindrical rotating cell-culture vessel with thin culture-medium layer of large surface area provides exchange of nutrients and products of metabolism with minimal agitation. Rotation causes averaging of buoyant forces otherwise separating components of different densities. Vessel enables growth of cells in homogeneous distribution with little agitation and little shear stress.

New technologies for managing cotton modules

USDA-ARS?s Scientific Manuscript database

New cotton harvesters with the ability to form seed cotton modules have changed the way that cotton is stored and handled before ginning. Cylindrical or “round” modules formed by John Deere cotton pickers and strippers are wrapped in three layers of plastic material to protect the cotton and mainta...

Compensation of shear waves in photoacoustic tomography with layered acoustic media.

PubMed

Schoonover, Robert W; Anastasio, Mark A

2011-10-01

An image reconstruction formula is presented for photoacoustic computed tomography that accounts for conversion between longitudinal and shear waves in a planar-layered acoustic medium. We assume the optical absorber that produces the photoacoustic wave field is embedded in a single fluid layer and any elastic solid layers present are separated by one or more fluid layers. The measurement aperture is assumed to be planar. Computer simulation studies are conducted to demonstrate and investigate the proposed reconstruction formula.

Two-Phase Solid/Fluid Simulation of Dense Granular Flows With Dilatancy Effects

NASA Astrophysics Data System (ADS)

Mangeney, A.; Bouchut, F.; Fernández-Nieto, E. D.; Kone, E. H.; Narbona-Reina, G.

2016-12-01

Describing grain/fluid interaction in debris flows models is still an open and challenging issue with key impact on hazard assessment [1]. We present here a two-phase two-thin-layer model for fluidized debris flows that takes into account dilatancy effects. It describes the velocity of both the solid and the fluid phases, the compression/ dilatation of the granular media and its interaction with the pore fluid pressure [2]. The model is derived from a 3D two-phase model proposed by Jackson [3] and the mixture equations are closed by a weak compressibility relation. This relation implies that the occurrence of dilation or contraction of the granular material in the model depends on whether the solid volume fraction is respectively higher or lower than a critical value. When dilation occurs, the fluid is sucked into the granular material, the pore pressure decreases and the friction force on the granular phase increases. On the contrary, in the case of contraction, the fluid is expelled from the mixture, the pore pressure increases and the friction force diminishes. To account for this transfer of fluid into and out of the mixture, a two-layer model is proposed with a fluid or a solid layer on top of the two-phase mixture layer. Mass and momentum conservation are satisfied for the two phases, and mass and momentum are transferred between the two layers. A thin-layer approximation is used to derive average equations. Special attention is paid to the drag friction terms that are responsible for the transfer of momentum between the two phases and for the appearance of an excess pore pressure with respect to the hydrostatic pressure. By comparing quantitatively the results of simulation and laboratory experiments on submerged granular flows, we show that our model contains the basic ingredients making it possible to reproduce the interaction between the granular and fluid phases through the change in pore fluid pressure. In particular, we analyse the different time scales in the model and their role in granular/fluid flow dynamics. References[1] R. Delannay, A. Valance, A. Mangeney, O. Roche, P. Richard, J. Phys. D: Appl. Phys., in press (2016). [2] F. Bouchut, E. D. Fernández-Nieto, A. Mangeney, G. Narbona-Reina, J. Fluid Mech., 801, 166-221 (2016). [3] R. Jackson, Cambridges Monographs on Mechanics (2000).

Magnetically Actuated Propellant Orientation Experiment, Controlling Fluid Motion With Magnetic Fields in a Low-Gravity Environment

NASA Technical Reports Server (NTRS)

Martin, J. J.; Holt, J. B.

2000-01-01

This report details the results of a series of fluid motion experiments to investigate the use of magnets to orient fluids in a low-gravity environment. The fluid of interest for this project was liquid oxygen (LO2) since it exhibits a paramagnetic behavior (is attracted to magnetic fields). However, due to safety and handling concerns, a water-based ferromagnetic mixture (produced by Ferrofluidics Corporation) was selected to simplify procedures. Three ferromagnetic fluid mixture strengths and a nonmagnetic water baseline were tested using three different initial fluid positions with respect to the magnet. Experiment accelerometer data were used with a modified computational fluid dynamics code termed CFX-4 (by AEA Technologies) to predict fluid motion. These predictions compared favorably with experiment video data, verifying the code's ability to predict fluid motion with and without magnetic influences. Additional predictions were generated for LO2 with the same test conditions and geometries used in the testing. Test hardware consisted of a cylindrical Plexiglas tank (6-in. bore with 10-in. length), a 6,000-G rare Earth magnet (10-in. ring), three-axis accelerometer package, and a video recorder system. All tests were conducted aboard the NASA Reduced-Gravity Workshop, a KC-135A aircraft.

Reflection and transmission coefficients of a single layer in poroelastic media.

PubMed

Corredor, Robiel Martinez; Santos, Juan E; Gauzellino, Patricia M; Carcione, José M

2014-06-01

Wave propagation in poroelastic media is a subject that finds applications in many fields of research, from geophysics of the solid Earth to material science. In geophysics, seismic methods are based on the reflection and transmission of waves at interfaces or layers. It is a relevant canonical problem, which has not been solved in explicit form, i.e., the wave response of a single layer, involving three dissimilar media, where the properties of the media are described by Biot's theory. The displacement fields are recast in terms of potentials and the boundary conditions at the two interfaces impose continuity of the solid and fluid displacements, normal and shear stresses, and fluid pressure. The existence of critical angles is discussed. The results are verified by taking proper limits-zero and 100% porosity-by comparison to the canonical solutions corresponding to single-phase solid (elastic) media and fluid media, respectively, and the case where the layer thickness is zero, representing an interface separating two poroelastic half-spaces. As examples, it was calculated the reflection and transmission coefficients for plane wave incident at a highly permeable and compliant fluid-saturated porous layer, and the case where the media are saturated with the same fluid.

The effect of geometry and operation conditions on the performance of a gas-liquid cylindrical cyclone separator with new structure

NASA Astrophysics Data System (ADS)

Han, Qing; Zhang, Chi; Xu, Bo; Chen, Jiangping

2013-07-01

The hydrodynamic flow behavior, effects of geometry and working conditions of a gas-liquid cylindrical cyclone separator with a new structure are investigated by computational fluid dynamic and experiment. Gas liquid cylindrical cyclone separator is widely used in oil industry, refrigeration system because of its simple structure, high separating efficiency, little maintenance and no moving parts nor internal devices. In this work, a gas liquid cylindrical cyclone separator with new structure used before evaporator in refrigeration system can remove the vapor from the mixture and make evaporator compact by improving its heat exchange efficiency with the lower inlet quality. It also decreases evaporator pressure drop and reduces compressor work. The two pipes are placed symmetrically which makes each of them can be treated as inlet. It means when the fluids flow reverse, the separator performance will not be influence. Four samples with different geometry parameters are tested by experiment with different inlet quality (0.18-0.33), inlet mass flow rate (65-100kg/h). Compared with the experimental data, CFD simulation results show a good agreement. Eulerian multiphase model and Reynolds Stress Turbulence model are applied in the CFD simulation and obtained the inner flow field such as phase path lines, tangential velocity profiles and pressure and volume of fraction distribution contours. The separator body diameter (24, 36, 48mm) and inlet diameter (3.84, 4.8, 5.76mm) decide the maximum tangential velocity which results in the centrifugal force. The tangential velocity profiles are simulated and compared among different models. The higher tangential velocity makes higher quality of gas outlet but high pressure drop at the same time. Decreasing the inlet diameter increases quality of gas outlet pipe and pressure drop. High gas outlet quality is cost at high pressure drop. Increasing of separator diameter makes gas outlet quality increase first and then decrease but the pressure drop decreases all the way. The offset (0, 2.4, 3.6mm) of gas outlet is an insensitive factor which influences the quality and pressure drop little.

Fluid-driven Fractures and Backflow in a Multilayered Elastic Matrix

NASA Astrophysics Data System (ADS)

Smiddy, Samuel; Lai, Ching-Yao; Stone, Howard

2016-11-01

We study the dynamics when pressurized fluid is injected at a constant flow rate into a multi-layered elastic matrix. In particular, we report experiments of such crack propagation as a function of orientation and distance from the contact of the layers. Subsequently we study the shape and propagation of the fluid along the contact of layers as well as volume of fluid remaining in the matrix once the injection pressure is released and "flowback" occurs. The experiments presented here may mimic the interaction between hydraulic fractures and pre-existing fractures and the dynamics of flowback in hydraulic fracturing. Study made possible by the Andlinger Center for Energy and the Environment and the Fred Fox Fund.

A high-performance magnetic shield with large length-to-diameter ratio.

PubMed

Dickerson, Susannah; Hogan, Jason M; Johnson, David M S; Kovachy, Tim; Sugarbaker, Alex; Chiow, Sheng-wey; Kasevich, Mark A

2012-06-01

We have demonstrated a 100-fold improvement in the magnetic field uniformity on the axis of a large aspect ratio, cylindrical, mumetal magnetic shield by reducing discontinuities in the material of the shield through the welding and re-annealing of a segmented shield. The three-layer shield reduces Earth's magnetic field along an 8 m region to 420 μG (rms) in the axial direction, and 460 and 730 μG (rms) in the two transverse directions. Each cylindrical shield is a continuous welded tube which has been annealed after manufacture and degaussed in the apparatus. We present both experiments and finite element analysis that show the importance of uniform shield material for large aspect ratio shields, favoring a welded design over a segmented design. In addition, we present finite element results demonstrating the smoothing of spatial variations in the applied magnetic field by cylindrical magnetic shields. Such homogenization is a potentially useful feature for precision atom interferometric measurements.

Development of a collapsible reinforced cylindrical space observation window

NASA Technical Reports Server (NTRS)

Khan, A. Q.

1971-01-01

Existing material technology was applied to the development of a collapsible transparent window suitable for manned spacecraft structures. The effort reported encompasses the evaluation of flame retardants intended for use in the window matrix polymer, evaluation of reinforcement angle which would allow for a twisting pantographing motion as the cylindrical window is mechanically collapsed upon itself, and evaluation of several reinforcement embedment methods. A fabrication technique was developed to produce a reinforced cylindrical space window of 45.7 cm diameter and 61.0 cm length. The basic technique involved the application of a clear film on a male-section mold; winding axial and girth reinforcements and vacuum casting the outer layer. The high-strength transparent window composite consisted of a polyether urethane matrix reinforced with an orthogonal pattern of black-coated carbon steel wire cable. A thin film of RTV silicone rubber was applied to both surfaces of the urethane. The flexibility, retraction system, and installation system are described.

Boundary Layer Theory. Part 1; Laminar Flows

NASA Technical Reports Server (NTRS)

Schlichting, H.

1949-01-01

The purpose of this presentation is to give you a survey of a field of aerodynamics which has for a number of years been attracting an ever growing interest. The subject is the theory of flows with friction, and, within that field, particularly the theory of friction layers, or boundary layers. As you know, a great many considerations of aerodynamics are based on the so-called ideal fluid, that is, the frictionless incompressible fluid. By neglect of compressibility and friction the extensive mathematical theory of the ideal fluid (potential theory) has been made possible.

Membranes having aligned 1-D nanoparticles in a matrix layer for improved fluid separation

DOEpatents

Revanur, Ravindra; Lulevich, Valentin; Roh, Il Juhn; Klare, Jennifer E.; Kim, Sangil; Noy, Aleksandr; Bakajin, Olgica

2015-12-22

Membranes for fluid separation are disclosed. These membranes have a matrix layer sandwiched between an active layer and a porous support layer. The matrix layer includes 1-D nanoparticles that are vertically aligned in a porous polymer matrix, and which substantially extend through the matrix layer. The active layer provides species-specific transport, while the support layer provides mechanical support. A matrix layer of this type has favorable surface morphology for forming the active layer. Furthermore, the pores that form in the matrix layer tend to be smaller and more evenly distributed as a result of the presence of aligned 1-D nanoparticles. Improved performance of separation membranes of this type is attributed to these effects.

Swept Impinging Oblique Shock/Boundary-Layer Interactions

NASA Astrophysics Data System (ADS)

Little, Jesse; Threadgill, James; Stab, Ilona

2016-11-01

Oblique shock waves impinging on boundary layers are common flow features associated with high-speed flows around complex body geometries and through internal channel flows. The increasingly three-dimensional surface geometries of modern vehicles has led to a prevalence of complex shock/boundary-layer interactions. Sweep has been observed to vary the interaction structure, unsteadinesses, and similarity scalings. Sharp-fins and highly-swept ramps have been noted to induce a quasi-conical development of the interaction, in contrast to a quasi-cylindrical scaling observed in low-sweep interactions. However, swept impinging oblique shock cases have largely been overlooked, with evidence of only cylindrical similarities observed in hypersonic conditions. Flow deflection beyond the maximum turning angle has been proposed as the mechanism for conical interaction development but such behavior has not been established for the present configuration. This study examines the effect of sweep on the interaction induced by a 12.5° generator in Mach 2.3 flow using oil-flow, Schlieren and PIV. Results document the development of similarity scalings at various angles of sweep, and highlight the difficulty in replicating a quasi-infinite span conditions in a moderately sized wind tun Supported by the Air Force Office of Scientific Research (FA9550-15-1-0430) and Raytheon Missile Systems.

Vortex Interactions from a Finite Span Cylinder with a Laminar Boundary Layer for Varied Parameters

NASA Astrophysics Data System (ADS)

Gildersleeve, Samantha; Amitay, Michael

2017-11-01

Flow structures around a stationary, wall-mounted, finite-span cylindrical pin were investigated experimentally over a flat plate to explore the effects of varied aspect ratio and pin mean height with respect to the local boundary layer. Nine static pin configurations were tested where the pin's mean height to the local boundary layer thickness were 0.5, 1, and 1.5 for a range of aspect ratios between 0.125 and 1.125. The freestream velocity was fixed at 11 m/s, corresponding to ReD 2800, 5600, and 8400, respectively. Three-dimensional flowfields were reconstructed and analyzed from SPIV measurements where data were collected along cross-stream planes in the wake of the pin. This study focuses on three dominant vortical patterns associated with a finite span cylinder: the arch-type vortex horseshoe vortex, and the tip vortices Results indicate that both the aspect ratio and mean height play an important role in the behavior and interactions of these vortex structures which alter the wake characteristics significantly. Understanding the mechanisms by which the vortical structures may be strengthened while reducing adverse local pressure drag are key for developing more efficient means of passive and/or active flow control through finite span cylindrical pins and will be discussed in further detail. NDSEG Fellowship for Samantha Gildersleeve.

Bulk Nonlinear Elastic Strain Waves in a Bilayer Coaxial Cylindrical Rod

NASA Astrophysics Data System (ADS)

Gula, I. A.; Samsonov, A. M.

2017-12-01

The problem of the propagation of long nonlinear elastic strain waves in a bilayer coaxial cylindrical rod with an ideal contact between the layers has been considered. Expressions for transverse displacements through longitudinal displacements have been derived. The former satisfies free boundary conditions and continuity conditions for displacements and stresses at the interlayer interface with the desired accuracy. It has been shown how these expressions generalize the well-known plane-section and Love hypotheses for an isotropic homogeneous rod. An equation for the propagation of a nonlinearly elastic strain longitudinal wave has been derived, and its particular solution in the form of a solitary traveling wave has been studied.

Free surface convection in a bounded cylindrical geometry

NASA Astrophysics Data System (ADS)

Vrentas, J. S.; Narayanan, R.; Agrawal, S. S.

1981-09-01

Surface tension-driven convection and buoyancy-driven convection in a bounded cylindrical geometry with a free surface are studied for a range of aspect ratios and Nusselt numbers. The thermal convection is in a liquid layer contained in a vertical circular cylinder with a single free boundary, the top surface, which is in contact with an inviscid gas phase. A different method is also developed for analyzing free convection problems using Green's functions, reducing the problem to the solution of an integral equation. Linear theory and some aspects of a nonlinear analysis are utilized to determine the critical Marangoni and Rayleigh numbers, the structure of the convective motion, the direction of flow, and the nature of the bifurcation branching.

Self shielding in cylindrical fissile sources in the APNea system

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

Hensley, D.

1997-02-01

In order for a source of fissile material to be useful as a calibration instrument, it is necessary to know not only how much fissile material is in the source but also what the effective fissile content is. Because uranium and plutonium absorb thermal neutrons so Efficiently, material in the center of a sample is shielded from the external thermal flux by the surface layers of the material. Differential dieaway measurements in the APNea System of five different sets of cylindrical fissile sources show the various self shielding effects that are routinely encountered. A method for calculating the self shieldingmore » effect is presented and its predictions are compared with the experimental results.« less

Pt-coated cylindrical micropatterned honeycomb Petri dishes as an efficient TCO-free counter electrode in liquid junction photovoltaic devices

NASA Astrophysics Data System (ADS)

Dao, Van-Duong; Bui, Van-Tien; Choi, Ho-Suk

2018-02-01

The Pt layer deposited on a cylindrical micro cavity patterned Petri dish, which is produced using a one-step solvent-immersion phase separation, is fabricated for the first time as an FTO-free counter electrode (CE) for dye-sensitized solar cells (DSCs). Due to the high specific active surface area of the Pt-deposited honeycomb substrate CE, the efficiency of the DSC using the developed CE substrate is enhanced by 14.5% compared with the device using a Pt-sputtered flat substrate. This design strategy has potential in fabricating highly efficient and low-cost CE materials with FTO-free substrates for DSCs.

Multilayer insulation blanket, fabricating apparatus and method

DOEpatents

Gonczy, John D.; Niemann, Ralph C.; Boroski, William N.

1992-01-01

An improved multilayer insulation blanket for insulating cryogenic structures operating at very low temperatures is disclosed. An apparatus and method for fabricating the improved blanket are also disclosed. In the improved blanket, each successive layer of insulating material is greater in length and width than the preceding layer so as to accommodate thermal contraction of the layers closest to the cryogenic structure. The fabricating apparatus has a rotatable cylindrical mandrel having an outer surface of fixed radius that is substantially arcuate, preferably convex, in cross-section. The method of fabricating the improved blanket comprises (a) winding a continuous sheet of thermally reflective material around the circumference of the mandrel to form multiple layers, (b) binding the layers along two lines substantially parallel to the edges of the circumference of the mandrel, (c) cutting the layers along a line parallel to the axle of the mandrel, and (d) removing the bound layers from the mandrel.

Method of fabricating a multilayer insulation blanket

DOEpatents

Gonczy, John D.; Niemann, Ralph C.; Boroski, William N.

1993-01-01

An improved multilayer insulation blanket for insulating cryogenic structures operating at very low temperatures is disclosed. An apparatus and method for fabricating the improved blanket are also disclosed. In the improved blanket, each successive layer of insulating material is greater in length and width than the preceding layer so as to accommodate thermal contraction of the layers closest to the cryogenic structure. The fabricating apparatus has a rotatable cylindrical mandrel having an outer surface of fixed radius that is substantially arcuate, preferably convex, in cross-section. The method of fabricating the improved blanket comprises (a) winding a continuous sheet of thermally reflective material around the circumference of the mandrel to form multiple layers, (b) binding the layers along two lines substantially parallel to the edges of the circumference of the mandrel, (c) cutting the layers along a line parallel to the axle of the mandrel, and (d) removing the bound layers from the mandrel.

Method of fabricating a multilayer insulation blanket

DOEpatents

Gonczy, J.D.; Niemann, R.C.; Boroski, W.N.

1993-07-06

An improved multilayer insulation blanket for insulating cryogenic structures operating at very low temperatures is disclosed. An apparatus and method for fabricating the improved blanket are also disclosed. In the improved blanket, each successive layer of insulating material is greater in length and width than the preceding layer so as to accommodate thermal contraction of the layers closest to the cryogenic structure. The fabricating apparatus has a rotatable cylindrical mandrel having an outer surface of fixed radius that is substantially arcuate, preferably convex, in cross-section. The method of fabricating the improved blanket comprises (a) winding a continuous sheet of thermally reflective material around the circumference of the mandrel to form multiple layers, (b) binding the layers along two lines substantially parallel to the edges of the circumference of the mandrel, (c) cutting the layers along a line parallel to the axle of the mandrel, and (d) removing the bound layers from the mandrel.

Multilayer insulation blanket, fabricating apparatus and method

DOEpatents

Gonczy, J.D.; Niemann, R.C.; Boroski, W.N.

1992-09-01

An improved multilayer insulation blanket for insulating cryogenic structures operating at very low temperatures is disclosed. An apparatus and method for fabricating the improved blanket are also disclosed. In the improved blanket, each successive layer of insulating material is greater in length and width than the preceding layer so as to accommodate thermal contraction of the layers closest to the cryogenic structure. The fabricating apparatus has a rotatable cylindrical mandrel having an outer surface of fixed radius that is substantially arcuate, preferably convex, in cross-section. The method of fabricating the improved blanket comprises (a) winding a continuous sheet of thermally reflective material around the circumference of the mandrel to form multiple layers, (b) binding the layers along two lines substantially parallel to the edges of the circumference of the mandrel, (c) cutting the layers along a line parallel to the axle of the mandrel, and (d) removing the bound layers from the mandrel. 7 figs.

Directed Self-Assembly on Photo-Crosslinked Polystyrene Sub-Layers: Nanopattern Uniformity and Orientation

PubMed Central

Koh, Haeng-Deog; Kim, Mi-Jeong

2016-01-01

A photo-crosslinked polystyrene (PS) thin film is investigated as a potential guiding sub-layer for polystyrene-block-poly (methyl methacrylate) block copolymer (BCP) cylindrical nanopattern formation via topographic directed self-assembly (DSA). When compared to a non-crosslinked PS brush sub-layer, the photo-crosslinked PS sub-layer provided longer correlation lengths of the BCP nanostructure, resulting in a highly uniform DSA nanopattern with a low number of BCP dislocation defects. Depending on the thickness of the sub-layer used, parallel or orthogonal orientations of DSA nanopattern arrays were obtained that covered the entire surface of patterned Si substrates, including both trench and mesa regions. The design of DSA sub-layers and guide patterns, such as hardening the sub-layer by photo-crosslinking, nano-structuring on mesas, the relation between trench/mesa width, and BCP equilibrium period, were explored with a view to developing defect-reduced DSA lithography technology. PMID:28773768

Bound acoustic modes in the radiation continuum in isotropic layered systems without periodic structures

NASA Astrophysics Data System (ADS)

Maznev, A. A.; Every, A. G.

2018-01-01

We study the existence of guided acoustic modes in layered structures whose phase velocity is higher than that of bulk waves in a solid substrate or an adjacent fluid half space, which belong to the class of bound states in the radiation continuum (BICs). We demonstrate that in contrast to the electromagnetic case, non-symmetry-protected BICs exist in isotropic layered systems without periodic structures. Two systems supporting non-symmetry-protected sagittally polarized BICs have been identified: (i) a supported solid layer yields BICs whose phase velocity is higher than the transverse velocity of the substrate but lower than the longitudinal velocity; (ii) a supported solid layer loaded by a fluid half space supports BICs whose velocity is higher that the bulk velocity of the fluid but lower than acoustic velocities of the substrate. The latter case is a unique example of BICs in the sense that it does not involve an evanescent field in the fluid half space providing the radiation continuum. In either case, BICs are represented by isolated points in the dispersion relations located within "leaky" branches. We show that these BICs are robust with respect to small perturbations of the system parameters. Numerical results are provided for realistic materials combinations. We also show that no BICs exist in all-fluid layered structures, whereas in solid layered structures there are no shear horizontal BICs and no sagittally polarized BICs whose velocity exceeds the longitudinal velocity of the substrate.

Extrinsic extinction cross-section in the multiple acoustic scattering by fluid particles

NASA Astrophysics Data System (ADS)

Mitri, F. G.

2017-04-01

Cross-sections (and their related energy efficiency factors) are physical parameters used in the quantitative analysis of different phenomena arising from the interaction of waves with a particle (or multiple particles). Earlier works with the acoustic scattering theory considered such quadratic (i.e., nonlinear) quantities for a single scatterer, although a few extended the formalism for a pair of scatterers but were limited to the scattering cross-section only. Therefore, the standard formalism applied to viscous particles is not suitable for the complete description of the cross-sections and energy balance of the multiple-particle system because both absorption and extinction phenomena arise during the multiple scattering process. Based upon the law of the conservation of energy, this work provides a complete comprehensive analysis for the extrinsic scattering, absorption, and extinction cross-sections (i.e., in the far-field) of a pair of viscous scatterers of arbitrary shape, immersed in a nonviscous isotropic fluid. A law of acoustic extinction taking into consideration interparticle effects in wave propagation is established, which constitutes a generalized form of the optical theorem in multiple scattering. Analytical expressions for the scattering, absorption, and extinction cross-sections are derived for plane progressive waves with arbitrary incidence. The mathematical expressions are formulated in partial-wave series expansions in cylindrical coordinates involving the angle of incidence, the addition theorem for the cylindrical wave functions, and the expansion coefficients of the scatterers. The analysis shows that the multiple scattering cross-section depends upon the expansion coefficients of both scatterers in addition to an interference factor that depends on the interparticle distance. However, the extinction cross-section depends on the expansion coefficients of the scatterer located in a particular system of coordinates, in addition to the interference term. Numerical examples illustrate the analysis for two viscous fluid circular cylindrical cross-sections immersed in a non-viscous fluid. Computations for the (non-dimensional) scattering, absorption, and extinction cross-section factors are performed with particular emphasis on varying the angle of incidence, the interparticle distance, and the sizes, and the physical properties of the particles. A symmetric behavior is observed for the dimensionless multiple scattering cross-section, while asymmetries arise for both the dimensionless absorption and extinction cross-sections with respect to the angle of incidence. The present analysis provides a complete analytical and computational method for the prediction of cross-section and energy efficiency factors in multiple acoustic scattering of plane waves of arbitrary incidence by a pair of scatterers. The results can be used as a priori information in the direct or inverse characterization of multiple scattering systems such as acoustically engineered fluid metamaterials with reconfigurable periodicities, cloaking devices, liquid crystals, and other applications.

Microelectromechanical flow control apparatus

DOEpatents

Okandan, Murat [NE Albuquerque, NM

2009-06-02

A microelectromechanical (MEM) flow control apparatus is disclosed which includes a fluid channel formed on a substrate from a first layer of a nonconducting material (e.g. silicon nitride). A first electrode is provided on the first layer of the nonconducting material outside the flow channel; and a second electrode is located on a second layer of the nonconducting material above the first layer. A voltage applied between the first and second electrodes deforms the fluid channel to increase its cross-sectional size and thereby increase a flow of a fluid through the channel. In certain embodiments of the present invention, the fluid flow can be decreased or stopped by applying a voltage between the first electrode and the substrate. A peristaltic pumping of the fluid through the channel is also possible when the voltage is applied in turn between a plurality of first electrodes and the substrate. A MEM flow control assembly can also be formed by providing one or more MEM flow control devices on a common substrate together with a submicron filter. The MEM flow control assembly can optionally include a plurality of pressure sensors for monitoring fluid pressure and determining flow rates through the assembly.

Effects of non-uniform temperature gradients on surface tension driven two component magneto convection in a porous- fluid system

NASA Astrophysics Data System (ADS)

Manjunatha, N.; Sumithra, R.

2018-04-01

The problem of surface tension driven two component magnetoconvection is investigated in a Porous-Fluid system, consisting of anincompressible two component electrically conducting fluid saturatedporous layer above which lies a layer of the same fluid in the presence of a uniform vertical magnetic field. The lower boundary of the porous layeris rigid and the upper boundary of the fluid layer is free with surfacetension effects depending on both temperature and concentration, boththese boundaries are insulating to heat and mass. At the interface thevelocity, shear and normal stress, heat and heat flux, mass and mass fluxare assumed to be continuous suitable for Darcy-Brinkman model. Theeigenvalue problem is solved in linear, parabolic and inverted parabolictemperature profiles and the corresponding Thermal Marangoni Numberis obtained for different important physical parameters.

Layered reactive particles with controlled geometries, energies, and reactivities, and methods for making the same

DOEpatents

Fritz, Gregory M.; Weihs, Timothy P.; Grzyb, Justin A.

2016-07-05

An energetic composite having a plurality of reactive particles each having a reactive multilayer construction formed by successively depositing reactive layers on a rod-shaped substrate having a longitudinal axis, dividing the reactive-layer-deposited rod-shaped substrate into a plurality of substantially uniform longitudinal segments, and removing the rod-shaped substrate from the longitudinal segments, so that the reactive particles have a controlled, substantially uniform, cylindrically curved or otherwise rod-contoured geometry which facilitates handling and improves its packing fraction, while the reactant multilayer construction controls the stability, reactivity and energy density of the energetic composite.

Layered reactive particles with controlled geometries, energies, and reactivities, and methods for making the same

DOEpatents

Fritz, Gregory M; Knepper, Robert Allen; Weihs, Timothy P; Gash, Alexander E; Sze, John S

2013-04-30

An energetic composite having a plurality of reactive particles each having a reactive multilayer construction formed by successively depositing reactive layers on a rod-shaped substrate having a longitudinal axis, dividing the reactive-layer-deposited rod-shaped substrate into a plurality of substantially uniform longitudinal segments, and removing the rod-shaped substrate from the longitudinal segments, so that the reactive particles have a controlled, substantially uniform, cylindrically curved or otherwise rod-contoured geometry which facilitates handling and improves its packing fraction, while the reactant multilayer construction controls the stability, reactivity and energy density of the energetic composite.

Immiscibility of Fluid Phases at Magmatic-hydrothermal Transition: Formation of Various PGE-sulfide Mineralization for Layered Basic Intrusions

NASA Astrophysics Data System (ADS)

Zhitova, L.; Borisenko, A.; Morgunov, K.; Zhukova, I.

2007-12-01

Fluid inclusions in quartz of the Merensky Reef (Bushveld Complex, South Africa) and the Chineisky Pluton (Transbaikal Region, Russia) were studied using cryometry, microthermometry, Raman-spectroscopy, LA ICP- MS, scanning electronic microscopy, gas-chromatography and isotopic methods. This allowed us to document some examples of fluid phase separation resulting in formation of different types of PGE-sulfide mineralization for layered basic intrusions. The results obtained show at least three generations of fluid separated from boiling residual alumosilicate intercumulus liquid of the Merensky Reef. The earliest fluid phase composed of homogenous high-dense methane and nitrogen gas mixture was identified in primary gas and co-existing anomalous fluid inclusions from symplectitic quartz. The next generation, heterophase fluid, composed of brines containing a free low-dense (mostly of carbon dioxide) gas phase, was observed in primary multiphase and coexisting gas-rich inclusions of miarolitic quartz crystals. The latest generation was also a heterophase fluid (low salinity water-salt solution and free low-dense methane gas phase) found in primary water-salt and syngenetic gas inclusions from peripheral zones of miarolitic quartz crystals. For the Chineisky Pluton reduced endocontact magmatogene fluids changed to oxidized low salinity hydrothermal fluids in exocontact zone. This resulted in formation of sulfide-PGE enrichment marginal zones of intrusion. The results obtained give us a possibility to suggest that: 1) Fluid phase separation is a typical feature of magmatogene fluids for layered basic intrusions. 2) Reduced fluids can extract and transport substantial PGE and sulfide concentrations. 3) Oxidation of reduced fluids is one of the most important geochemical barriers causing abundant PGE minerals and sulfides precipitation. This in turn results in both formation of PGE reefs or enriched contact zones of layered basic intrusions. This work was supported by the Ministry for Russian Science and Education, Grant DSP.2.1.1.702, by RFBR Grants ## 07-05-00685, 07-05-00803, Grant VMTK-2007 IGM SB RAS.

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

NASA Astrophysics Data System (ADS)

Forestier, M.; Haldenwang, P.

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

Fluid surface behavior in low gravity. Center discretionary fund no. 83-21

NASA Technical Reports Server (NTRS)

Leslie, F.; Gans, R. F.; Schafer, C.

1985-01-01

Measurements of rotating equilibrium bubble shapes in the low-gravity environment of a free-falling aircraft are presented. Emphasis is placed on bubbles which intersect the container boundaries. These data are compared with theoretical profiles derived from Laplace's formula and are in good agreement with the measurements. Two types of instability are explored. The first occurs when the baffle spacing is too large for the bubble to intersect both the top and bottom boundaries. The second occurs when the hydrostatic pressure beneath a displaced free surface does not compensate for pressure change due to capillary forces. The interface shape depends on the contact angle, the radius of intersection with container, and the parameter F which is a measure of the relative importance of centrifugal force to surface tension. For isolated bubbles, F has a maximum value of 1/2. A further increase in F causes the bubble to break contact with the axis of rotation. For large values of F, the bubble becomes more cylindrical and the capillary rise occurs over a thinner layer so that the small radius of curvature can generate enough pressure drop to balance the increased hydrostatic contribution.

Reciprocating air flow for Li-ion battery thermal management to improve temperature uniformity

NASA Astrophysics Data System (ADS)

Mahamud, Rajib; Park, Chanwoo

The thermal management of traction battery systems for electrical-drive vehicles directly affects vehicle dynamic performance, long-term durability and cost of the battery systems. In this paper, a new battery thermal management method using a reciprocating air flow for cylindrical Li-ion (LiMn 2O 4/C) cells was numerically analyzed using (i) a two-dimensional computational fluid dynamics (CFD) model and (ii) a lumped-capacitance thermal model for battery cells and a flow network model. The battery heat generation was approximated by uniform volumetric joule and reversible (entropic) losses. The results of the CFD model were validated with the experimental results of in-line tube-bank systems which approximates the battery cell arrangement considered for this study. The numerical results showed that the reciprocating flow can reduce the cell temperature difference of the battery system by about 4 °C (72% reduction) and the maximum cell temperature by 1.5 °C for a reciprocation period of τ = 120 s as compared with the uni-directional flow case (τ = ∞). Such temperature improvement attributes to the heat redistribution and disturbance of the boundary layers on the formed on the cells due to the periodic flow reversal.

Topology and stability of a water-soybean-oil swirling flow

NASA Astrophysics Data System (ADS)

Carrión, Luis; Herrada, Miguel A.; Shtern, Vladimir N.

2017-02-01

This paper reveals and explains the flow topology and instability hidden in an experimental study by Tsai et al. [Tsai et al., Phys. Rev. E 92, 031002(R) (2015)], 10.1103/PhysRevE.92.031002. Water and soybean oil fill a sealed vertical cylindrical container. The rotating top disk induces the meridional circulation and swirl of both fluids. The experiment shows a flattop interface shape and vortex breakdown in the oil flow developing as the rotation strength R eo increases. Our numerical study shows that vortex breakdown occurs in the water flow at R eo=300 and in the oil flow at R eo=941 . As R eo increases, the vortex breakdown cell occupies most of the water domain and approaches the interface at R eo around 600. The rest of the (countercirculating) water separates from the axis as the vortex breakdown cells in the oil and water meet at the interface-axis intersection. This topological transformation of water flow significantly contributes to the development of the flattop shape. It is also shown that the steady axisymmetric flow suffers from shear-layer instability, which emerges in the water domain at R eo=810 .

The increase of apatite layer formation by the poly(3-hydroxybutyrate) surface modification of hydroxyapatite and β-tricalcium phosphate.

PubMed

Szubert, M; Adamska, K; Szybowicz, M; Jesionowski, T; Buchwald, T; Voelkel, A

2014-01-01

The aim of this study was the surface modification of hydroxyapatite and β-tricalcium phosphate by poly(3-hydroxybutyrate) grafting and characterization of modificates. The bioactivity examination was carried out by the determination to grow an apatite layer on modified materials during incubation in simulated body fluid at 37°C. The additional issue taken up in this paper was to investigate the influence of fluid replacement. The process of the surface modification of biomaterials was evaluated by means of infrared and Raman spectroscopy. Formation of the apatite layer was assessed by means of scanning electron microscopy and confirmed by energy dispersive, Raman and Fourier transformed infrared spectroscopy. During exposure in simulated body fluid, the variation of the zeta potential, pH measurement and relative weight was monitored. Examination of scanning electron microscopy micrographs suggests that modification of hydroxyapatite and β-tricalcium phosphate by poly(3-hydroxybutyrate) significantly increases apatite layer formation. Raman spectroscopy evaluation revealed that the formation of the apatite layer was more significant in the case of hydroxyapatite modificate, when compared to the β-tricalcium phosphate modificate. Both modificates were characterized by stable pH, close to the natural pH of human body fluids. Furthermore, we have shown that a weekly changed, simulated body fluid solution increases apatite layer formation. © 2013.

Unsteady Boundary-Layer Flow over Jerked Plate Moving in a Free Stream of Viscoelastic Fluid

PubMed Central

Mehmood, Ahmer; Ali, Asif; Saleem, Najma

2014-01-01

This study aims to investigate the unsteady boundary-layer flow of a viscoelastic non-Newtonian fluid over a flat surface. The plate is suddenly jerked to move with uniform velocity in a uniform stream of non-Newtonian fluid. Purely analytic solution to governing nonlinear equation is obtained. The solution is highly accurate and valid for all values of the dimensionless time 0 ≤ τ < ∞. Flow properties of the viscoelastic fluid are discussed through graphs. PMID:24892060

Compatibility of Silicone-Based Brake Fluids with Elastomeric Components of Army Vehicles and Weapon Systems.

DTIC Science & Technology

1980-02-01

propylene rubber) EPDM Brake valve parts and seals 80 EPDM (SAE, RM 69) Referee test slabs 70L VITON 0-rings 70 TN4 -i______ - -.- . .J....... TABLE 2...separated. The volume and hardness of two rubber test specimens was determined. One specimen was placed in the lower fluid layer (conventional fluid...and one specimen was suspended horizontally in the top fluid layer (silicone). The jar was stored on the laboratory shelf at ambient temperature. The

Numerical analysis of fluid flow and heat transfer during melting inside a cylindrical container for thermal energy storage system

NASA Astrophysics Data System (ADS)

Bellan, Selvan; Cheok, Cho Hyun; Gokon, Nobuyuki; Matsubara, Koji; Kodama, Tatsuya

2017-06-01

This paper presents a numerical analysis of unconstrained melting of high temperature(>1000K) phase change material (PCM) inside a cylindrical container. Sodium chloride and Silicon carbide have been used as phase change material and shell of the capsule respectively. The control volume discretization approach has been used to solve the conservation equations of mass, momentum and energy. The enthalpy-porosity method has been used to track the solid-liquid interface of the PCM during melting process. Transient numerical simulations have been performed in order to study the influence of radius of the capsule and the Stefan number on the heat transfer rate. The simulation results show that the counter-clockwise Buoyancy driven convection over the top part of the solid PCM enhances the melting rate quite faster than the bottom part.

A numerical simulation of magma motion, crustal deformation, and seismic radiation associated with volcanic eruptions

USGS Publications Warehouse

Nishimura, T.; Chouet, B.

2003-01-01

The finite difference method is used to calculate the magma dynamics, seismic radiation, and crustal deformation associated with a volcanic eruption. The model geometry consists of a cylindrical reservoir and narrow cylindrical conduit embedded in a homogeneous crust. We consider two models of eruption. In the first model, a lid caps the vent and the magma is overpressurized prior to the eruption. The eruption is triggered by the instantaneous removal of the lid, at which point the exit pressure becomes equal to the atmospheric pressure. In the second model, a plug at the reservoir outlet allows pressurization of only the magmatic fluid in the reservoir before the eruption. Magma transfer between the reservoir and conduit is triggered by the instantaneous removal of the plug, and the eruption occurs when the pressure at the conduit orifice exceeds the material strength of the lid capping the vent. In both models, magma dynamics are expressed by the equations of mass and momentum conservation in a compressible fluid, in which fluid expansion associated with depressurization is accounted for by a constitutive law relating pressure and density. Crustal motions are calculated from the equations of elastodynamics. The fluid and solid are dynamically coupled by applying the continuity of wall velocities and normal stresses across the conduit and reservoir boundaries. Free slip is allowed at the fluid-solid boundary. Both models predict the gradual depletion of the magma reservoir, which causes crustal deformation observed as a long-duration dilatational signal. Superimposed on this very-long-period (VLP) signal generated by mass transport are long-period (LP) oscillations of the magma reservoir and conduit excited by the acoustic resonance of the reservoir-conduit system during the eruption. The volume of the reservoir, vent size, and magma properties control the duration of VLP waves and dominant periods of LP oscillations. The second model predicts that when the magmatic fluid reaches the vent, a high-pressure pulse occurs at this location in accordance with the basic theory of compressible fluid dynamics. This abrupt pressure increase just beneath the vent is consistent with observed seismograms in which pulse-like Rayleigh waves excited by a shallow source are dominant. The strength of the lid plays an important role in the character of the seismograms and in defining the type of eruption observed.

Heat exchanger using graphite foam

DOEpatents

Campagna, Michael Joseph; Callas, James John

2012-09-25

A heat exchanger is disclosed. The heat exchanger may have an inlet configured to receive a first fluid and an outlet configured to discharge the first fluid. The heat exchanger may further have at least one passageway configured to conduct the first fluid from the inlet to the outlet. The at least one passageway may be composed of a graphite foam and a layer of graphite material on the exterior of the graphite foam. The layer of graphite material may form at least a partial barrier between the first fluid and a second fluid external to the at least one passageway.

Are the Element Budget and the Occurrence of Polymetallic Nodules influenced by Fluids Circulating through the Oceanic Crust or/and Sediments?

NASA Astrophysics Data System (ADS)

Heller, C.; Kuhn, T.

2016-12-01

Hydrothermal fluids can extract significant amounts of heat from oceanic lithosphere by lateral fluid flow through permeable basaltic crust of an age of up to 65 Ma. Fluid recharge and discharge occur at basement outcrops in between impermeable pelagic sediments. Recharge of oxic seawater causes upward oxygen diffusion into sediments overlying the permeable basalt in areas proximal to recharge sites. It is suggested that this oxygen have a strong impact on sediments and Mn nodules during fluid exposure time. The aim of this study is to investigate if and how fluid flow through oceanic crust influence the distribution and element budget of the Mn nodules. For that purpose, Mn nodules were examined which were collected during the research cruise SO240 in the equatorial NE Pacific at sites with and without faults in the upper basement and overlying sediments. Faults are thought to be preferred fluid pathways. Nodules were found on the sediment surface as well as in the sediment and consist of different nm- to µm-thick, dense and porous layers. The geochemical composition of bulk nodules and single nodule layers were determined by XRF, ICP-MS/OES and by high resolution analyses with EMPA and LA-ICP-MS. Dense layers have low Mn/Fe ratios (<4) and high concentrations of Co, Zr and REY, while porous layers are characterized by high Mn/Fe ratios (> 10) and high Ni+Cu and Li concentrations (Koschinsky et al., 2010; Kuhn et al., 2010). The different compositions depends on different formation processes of the layers. Dense layers are formed by element precipitation from oxygen rich seawater and/or pore water and are called hydrogenetic, while porous layers were formed by precipitation from almost oxygen-free (suboxic) pore water (Burns & Burns, 1978; Glasby, 2006) and are called diagenetic (Halbach et al., 1988). Preliminary results show that there are significant differences between the geochemical composition of nodules grown at sediment surface and those found within sediments. Compared to surface nodules, buried nodules are enriched in Co and W, but has lower concentration of Mo, Ba, Zn, Li. Distribution of Rare Earth Elements (REY) are also different. Especially, the element distribution in the bulk samples and the single layers of the buried nodules could be used to find a possible influence of circulating fluids on nodule formation.

Cyclone separator having boundary layer turbulence control

DOEpatents

Krishna, Coimbatore R.; Milau, Julius S.

1985-01-01

A cyclone separator including boundary layer turbulence control that is operable to prevent undue build-up of particulate material at selected critical areas on the separator walls, by selectively varying the fluid pressure at those areas to maintain the momentum of the vortex, thereby preventing particulate material from inducing turbulence in the boundary layer of the vortical fluid flow through the separator.

Generation of long subharmonic internal waves by surface waves

NASA Astrophysics Data System (ADS)

Tahvildari, Navid; Kaihatu, James M.; Saric, William S.

2016-10-01

A new set of Boussinesq equations is derived to study the nonlinear interactions between long waves in a two-layer fluid. The fluid layers are assumed to be homogeneous, inviscid, incompressible, and immiscible. Based on the Boussinesq equations, an analytical model is developed using a second-order perturbation theory and applied to examine the transient evolution of a resonant triad composed of a surface wave and two oblique subharmonic internal waves. Wave damping due to weak viscosity in both layers is considered. The Boussinesq equations and the analytical model are verified. In contrast to previous studies which focus on short internal waves, we examine long waves and investigate some previously unexplored characteristics of this class of triad interaction. In viscous fluids, surface wave amplitudes must be larger than a threshold to overcome viscous damping and trigger internal waves. The dependency of this critical amplitude as well as the growth and damping rates of internal waves on important parameters in a two-fluid system, namely the directional angle of the internal waves, depth, density, and viscosity ratio of the fluid layers, and surface wave amplitude and frequency is investigated.

Phase diagram of a symmetric electron–hole bilayer system: a variational Monte Carlo study

NASA Astrophysics Data System (ADS)

Sharma, Rajesh O.; Saini, L. K.; Prasad Bahuguna, Bhagwati

2018-05-01

We study the phase diagram of a symmetric electron–hole bilayer system at absolute zero temperature and in zero magnetic field within the quantum Monte Carlo approach. In particular, we conduct variational Monte Carlo simulations for various phases, i.e. the paramagnetic fluid phase, the ferromagnetic fluid phase, the anti-ferromagnetic Wigner crystal phase, the ferromagnetic Wigner crystal phase and the excitonic phase, to estimate the ground-state energy at different values of in-layer density and inter-layer spacing. Slater–Jastrow style trial wave functions, with single-particle orbitals appropriate for different phases, are used to construct the phase diagram in the (r s , d) plane by finding the relative stability of trial wave functions. At very small layer separations, we find that the fluid phases are stable, with the paramagnetic fluid phase being particularly stable at and the ferromagnetic fluid phase being particularly stable at . As the layer spacing increases, we first find that there is a phase transition from the ferromagnetic fluid phase to the ferromagnetic Wigner crystal phase when d reaches 0.4 a.u. at r s   =  20, and before there is a return to the ferromagnetic fluid phase when d approaches 1 a.u. However, for r s   <  20 and a.u., the excitonic phase is found to be stable. We do not find that the anti-ferromagnetic Wigner crystal is stable over the considered range of r s and d. We also find that as r s increases, the critical layer separations for Wigner crystallization increase.