Reflections on the Historical Narrative of Jessica Park, an Artist with Autism
ERIC Educational Resources Information Center
Furniss, Gillian J.
2010-01-01
This viewpoint discusses the history of Jessica Park, a professional artist who is an adult with autism. The narrative was constructed from historical descriptive research conducted by the author using published accounts and interviews with the artist, her mother, and two childhood companions. Examples of artwork produced in elementary through…
Jessica's Journey: Transforming School Culture
ERIC Educational Resources Information Center
Grover, Kenneth O.
2014-01-01
Kenneth Grover, the principal at Innovations Early College High School in Salt Lake City, Utah, describes a student he calls Jessica who is, unfortunately, one of thousands of students across the country entering and walking away from high school during their first year. These students' efforts are sincere, their attendance superb, and their…
ERIC Educational Resources Information Center
Roberts, Sherron Killingsworth
2010-01-01
With the 2008 reissue of Francine Pascal's (1983) "Sweet Valley High", the popular cultural icons of twins Jessica and Elizabeth have been revitalized. Jessica and Elizabeth are the much-beloved protagonists in romance novels strategically targeted for young adults in "Sweet Valley High" or "Sweet Valley U", and for first- and second-grade readers…
Interview with John Taylor Gatto.
ERIC Educational Resources Information Center
Becker, Ellen
1994-01-01
Introduces ex-teacher and author John Taylor Gatto's experiences and views on education, including contradictory patterns of family life and education in the United States, based on traditions of various immigrant groups; deleterious impacts of standardization and institutional usurpation of family functions; and conflict between the development…
ERIC Educational Resources Information Center
Hanson, Art
Two books that use documentary photography to examine social problems--"You Have Seen Their Faces," a 1937 study of Southern sharecroppers by Margaret Bourke-White and Erskine Caldwell, and "An American Exodus," a 1939 examination of the migration of farm families by Dorothea Lange and Paul S. Taylor--are compared in this paper. After relating the…
Taylor Business Institute, Report.
ERIC Educational Resources Information Center
Barber, Jerry
The Office of the State Comptroller in New York audited the records and procedures used in administering the Tuition Assistance Program (TAP) at Taylor Business Institute (Taylor) for the academic years 1995-96 through 1997-98. Taylor, located in Manhattan, offers both degree programs and diploma programs in Accounting, Business Management,…
ERIC Educational Resources Information Center
Lonergan, David
2011-01-01
Frederick Winslow Taylor (1856-1915) was an efficiency expert whose concerns were less about avoiding worker fatigue and more about increasing profit margins by any means necessary. Taylor was devoted to finding the One Best Way to carry out a task and then training workers to do that task unvaryingly; attempts by employees to improve their own…
Effects of the Jessica oil spill on artisanal fisheries in the Galápagos.
Born, Abraham F; Espinoza, Eduardo; Murillo, Juan Carlos; Nicolaides, Francis; Edgar, Graham J
2003-01-01
In contrast to local perceptions, the impact on the local Galápagos artisanal fishery of the 16 January 2001 grounding of the Jessica and subsequent oil spill was relatively minor. No significant changes in fishing effort, total fishing catches or catch-per-unit effort were detected after the spill based on analyses of fisheries monitoring data. Nevertheless, large boats tended to move away from sites near the path of the spill following the grounding in 2001, with no fishing recorded from the oil-affected regions of Floreana and southern Isabela in February 2001. The total fishing effort of small boats operating from the Jessica-grounding island of San Cristóbal also declined immediately after the spill, probably in part because such boats were used in clean up operations. During 2001, prices paid to fishers remained stable at levels higher than in 2000, with the notable anomaly that prices fell precipitously to 30% of previous levels during a 1-2 week period in early February 2001. Fish exports remained at similar levels for the years 2000 and 2001; however, as in the previous year, little fish product was exported from Galápagos in the month following the spill, with most fish product dried and stored for up to two months prior to transport to the continent. PMID:12810096
ERIC Educational Resources Information Center
Fialkoff, Francine
2009-01-01
In his 30 years as a library wholesaler, first as VP and general manager of Brodart Books, Library, and School Automation divisions and since 2000 as president of the Library & Education division of Baker & Taylor (B&T), George Coe has been instrumental in a whole host of innovations. They go way beyond the selection, processing, and delivery of…
ERIC Educational Resources Information Center
Stanovich, Keith E.; West, Richard F.
1994-01-01
Responds to Denny Taylor's critique in the same issue of an article by Richard F. West, Keith E. Stanovich, and H. R. Mitchell entitled "Reading in the Real World and Its Correlates," published in an earlier issue of "Reading Research Quarterly." (HB)
ERIC Educational Resources Information Center
Roberts, Sherron Killingsworth
Jessica and Elizabeth are two female characters, twins, featured throughout Francine Pascal's Sweet Valley series, the Bantam Publishers popular series for girls from elementary school through junior high, high school, university, and well into adulthood. This paper notes that these books are a part of the same formula that are used for romance…
NASA Astrophysics Data System (ADS)
Sprague, M. A.; Weidman, P. D.; Macumber, S.; Fischer, P. F.
2008-01-01
The stability of circular Couette flow in discontinuous axisymmetric geometries is investigated using numerical simulations and physical experiments. By contouring the geometry of the inner cylinder, Taylor vortices can be made to appear in discrete sections along the length of the cylinder while adjoining sections remain stable. The disparate flows are connected by transition regions that arise from the stability of the axially nonuniform base flow state. The geometry of the inner cylinder can be tailored to produce the simultaneous onset of Taylor vortices of different wavelength in neighboring sections. In another variant, a stack of inner cylinders of common radius are made to rotate independently to produce adjacent regions of stable and unstable flow.
Continuously tailored Taylor vortices
NASA Astrophysics Data System (ADS)
Sprague, M. A.; Weidman, P. D.
2009-11-01
Modified axisymmetric, finite-length Taylor-Couette (TC) cells with stationary outer cylinder and rotating inner cylinder are designed in an effort to produce simultaneous onset of toroidal vortices of continuously varying wavelength along the gap. For a given axial variation in the inner radius, the axial variation in the outer radius can be chosen such that at every axial position, the criterion for the onset of Taylor vortices in a corresponding classical TC cell is met. In one scenario, a conical inner cylinder is chosen and the shape of the outer cylinder is then determined by locally satisfying the onset criterion. In another scenario, the inner and outer radii are chosen such that the onset criterion is locally satisfied and the axial rate of change in the classical onset wave number is held constant. In both cases, the modified cells possess a large-scale meridional circulation wrought by the finite Ekman (Bödewadt) pumping on the inner (outer) cylinder walls. Using direct numerical simulation, it is found that for sufficiently large aspect ratio, there exists a critical rotation rate for the simultaneous transition from the base flow to counter-rotating toroidal vortices throughout the varying-radius region. The vortices propagate in the direction of decreasing gap width with a phase speed that decreases with increasing aspect ratio.
Overview of Rayleigh-Taylor instability
Sharp, D.H.
1983-01-01
The aim of this talk is to survey Rayleigh-Taylor instability, describing the phenomenology that occurs at a Taylor unstable interface, and reviewing attempts to understand these phenomena quantitatively.
Olson, B J; Cook, A W
2007-08-30
Beginning from a state of hydrostatic equilibrium, in which a heavy gas rests atop a light gas in a constant gravitational field, Rayleigh-Taylor instability at the interface will launch a shock wave into the upper fluid. The rising bubbles of lighter fluid act like pistons, compressing the heavier fluid ahead of the fronts and generating shocklets. These shocklets coalesce in multidimensional fashion into a strong normal shock, which increases in strength as it propagates upwards. Large-eddy simulations demonstrate that the shock Mach number increases faster in three dimensions than it does in two dimensions. The generation of shocks via Rayleigh-Taylor instability could have profound implications for astrophysical flows.
Bursting the Taylor cone bubble
NASA Astrophysics Data System (ADS)
Pan, Zhao; Truscott, Tadd
2014-11-01
A soap bubble fixed on a surface and placed in an electric field will take on the shape of a cone rather than constant curvature (dome) when the electrical field is not present. The phenomenon was introduced by J. Zeleny (1917) and studied extensively by C.T. Wilson & G.I. Taylor (1925). We revisit the Taylor cone problem by studying the deformation and bursting of soap bubbles in a point charge electric field. A single bubble takes on the shape of a cone in the electric field and a high-speed camera equipped with a micro-lens is used to observe the unsteady dynamics at the tip. Rupture occurs as a very small piece of the tip is torn away from the bubble toward the point charge. Based on experiments, a theoretical model is developed that predicts when rupture should occur. This study may help in the design of foam-removal techniques in engineering and provide a better understanding of an electrified air-liquid interface.
Taylor approximations of multidimensional linear differential systems
NASA Astrophysics Data System (ADS)
Lomadze, Vakhtang
2016-06-01
The Taylor approximations of a multidimensional linear differential system are of importance as they contain a complete information about it. It is shown that in order to construct them it is sufficient to truncate the exponential trajectories only. A computation of the Taylor approximations is provided using purely algebraic means, without requiring explicit knowledge of the trajectories.
Taylor Business Institute. Report 93-T-1.
ERIC Educational Resources Information Center
Attmore, Robert H.
Taylor Business Institute is a proprietary, degree-granting school located in New York City, offering various programs leading to two-year degrees and diplomas. An audit was conducted by the New York State Comptroller's Office of the records and procedures used by Taylor in certifying students' awards for the Tuition Assistance Program (TAP) and…
Taylorism and the Logic of Learning Outcomes
ERIC Educational Resources Information Center
Stoller, Aaron
2015-01-01
This essay examines the shared philosophical foundations of Fredrick W. Taylor's scientific management principles and the contemporary learning outcomes movement (LOM). It analyses the shared philosophical ground between the focal point of Taylor's system--"the task"--and the conceptualization and deployment of "learning…
33 CFR 117.335 - Taylor Creek.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Taylor Creek. 117.335 Section 117.335 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Florida § 117.335 Taylor Creek. The draw of US441 bridge, mile...
Douglas Taylor School: Rooted in Community
ERIC Educational Resources Information Center
Rourke, James; Boone, Elizabeth
2009-01-01
Inspiring students to become teachers and community leaders is a goal of Douglas Taylor School's leadership team. A feeling of continuity and connection are important to the school, which opened in the 19th century. Housed in a beautiful old school building in Chicago's South Side, Douglas Taylor School contains grades preK-8. To maintain the…
33 CFR 117.335 - Taylor Creek.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Taylor Creek. 117.335 Section 117.335 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Florida § 117.335 Taylor Creek. The draw of US441 bridge, mile...
33 CFR 117.987 - Taylor Bayou.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Taylor Bayou. 117.987 Section 117.987 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Texas § 117.987 Taylor Bayou. The draws of the Union...
33 CFR 117.987 - Taylor Bayou.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Taylor Bayou. 117.987 Section 117.987 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Texas § 117.987 Taylor Bayou. The draws of the Union...
33 CFR 117.987 - Taylor Bayou.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Taylor Bayou. 117.987 Section 117.987 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Texas § 117.987 Taylor Bayou. The draws of the Union...
33 CFR 117.987 - Taylor Bayou.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Taylor Bayou. 117.987 Section 117.987 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Texas § 117.987 Taylor Bayou. The draws of the Union...
33 CFR 117.987 - Taylor Bayou.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Taylor Bayou. 117.987 Section 117.987 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Texas § 117.987 Taylor Bayou. The draws of the Union...
Nested Taylor decomposition in multivariate function decomposition
NASA Astrophysics Data System (ADS)
Baykara, N. A.; Gürvit, Ercan
2014-12-01
Fluctuationlessness approximation applied to the remainder term of a Taylor decomposition expressed in integral form is already used in many articles. Some forms of multi-point Taylor expansion also are considered in some articles. This work is somehow a combination these where the Taylor decomposition of a function is taken where the remainder is expressed in integral form. Then the integrand is decomposed to Taylor again, not necessarily around the same point as the first decomposition and a second remainder is obtained. After taking into consideration the necessary change of variables and converting the integration limits to the universal [0;1] interval a multiple integration system formed by a multivariate function is formed. Then it is intended to apply the Fluctuationlessness approximation to each of these integrals one by one and get better results as compared with the single node Taylor decomposition on which the Fluctuationlessness is applied.
Taylor instability in rhyolite lava flows
NASA Technical Reports Server (NTRS)
Baum, B. A.; Krantz, W. B.; Fink, J. H.; Dickinson, R. E.
1989-01-01
A refined Taylor instability model is developed to describe the surface morphology of rhyolite lava flows. The effect of the downslope flow of the lava on the structures resulting from the Taylor instability mechanism is considered. Squire's (1933) transformation is developed for this flow in order to extend the results to three-dimensional modes. This permits assessing why ridges thought to arise from the Taylor instability mechanism are preferentially oriented transverse to the direction of lava flow. Measured diapir and ridge spacings for the Little and Big Glass Mountain rhyolite flows in northern California are used in conjunction with the model in order to explore the implications of the Taylor instability for flow emplacement. The model suggests additional lava flow features that can be measured in order to test whether the Taylor instability mechanism has influenced the flows surface morphology.
NASA Astrophysics Data System (ADS)
Murray, Natalie; Bourne, Neil; Field, John
1997-07-01
Brar and Bless pioneeered the use of plate impact upon bars as a technique for investigating the 1D stress loading of glass. We wish to extend this technique by applying VISAR and embedded stress gauge measurements to a symmetrical version of the test. In this configuration two rods impact one upon the other in a symmetrical version of the Taylor test geometry in which the impact is perfectly rigid in the centre of mass frame. Previous work in the laboratory has characterised the three glass types (float, borosilicate and a high density lead glass). These experiments will identify the 1D stress failure mechanisms from high-speed photography and the stress and particle velocity histories will be interpreted in the light of these results. The differences in response of the three glasses will be highlighted.
Nonideal Rayleigh-Taylor mixing
Sharp, David Howland; Lin, Hyun K; Iwerks, Justin G; Gliman, James G
2009-01-01
Rayleigh-Taylor mixing is a classical hydrodynamic Instability, which occurs when a light fluid pushes against a heavy fluid. The two main sources of nonideal behavior in Rayleigh-Taylor (RT) mixing are regularizations (physical and numerical) which produce deviations from a pure Euler equation, scale Invariant formulation, and non Ideal (i.e. experimental) initial conditions. The Kolmogorov theory of turbulence predicts stirring at all length scales for the Euler fluid equations without regularization. We Interpret mathematical theories of existence and non-uniqueness in this context, and we provide numerical evidence for dependence of the RT mixing rate on nonideal regularizations, in other words indeterminacy when modeled by Euler equations. Operationally, indeterminacy shows up as non unique solutions for RT mixing, parametrized by Schmidt and Prandtl numbers, In the large Reynolds number (Euler equation) limit. Verification and validation evidence is presented for the large eddy simulation algorithm used here. Mesh convergence depends on breaking the nonuniqueness with explicit use of the laminar Schmidt and PrandtJ numbers and their turbulent counterparts, defined in terms of subgrid scale models. The dependence of the mixing rate on the Schmidt and Prandtl numbers and other physical parameters will be illustrated. We demonstrate numerically the influence of initial conditions on the mixing rate. Both the dominant short wavelength Initial conditions and long wavelength perturbations are observed to playa role. By examination of two classes of experiments, we observe the absence of a single universal explanation, with long and short wavelength initial conditions, and the various physical and numerical regularizations contributing In different proportions In these two different contexts.
Nonideal Rayleigh–Taylor mixing
Lim, Hyunkyung; Iwerks, Justin; Glimm, James; Sharp, David H.
2010-01-01
Rayleigh–Taylor mixing is a classical hydrodynamic instability that occurs when a light fluid pushes against a heavy fluid. The two main sources of nonideal behavior in Rayleigh–Taylor (RT) mixing are regularizations (physical and numerical), which produce deviations from a pure Euler equation, scale invariant formulation, and nonideal (i.e., experimental) initial conditions. The Kolmogorov theory of turbulence predicts stirring at all length scales for the Euler fluid equations without regularization. We interpret mathematical theories of existence and nonuniqueness in this context, and we provide numerical evidence for dependence of the RT mixing rate on nonideal regularizations; in other words, indeterminacy when modeled by Euler equations. Operationally, indeterminacy shows up as nonunique solutions for RT mixing, parametrized by Schmidt and Prandtl numbers, in the large Reynolds number (Euler equation) limit. Verification and validation evidence is presented for the large eddy simulation algorithm used here. Mesh convergence depends on breaking the nonuniqueness with explicit use of the laminar Schmidt and Prandtl numbers and their turbulent counterparts, defined in terms of subgrid scale models. The dependence of the mixing rate on the Schmidt and Prandtl numbers and other physical parameters will be illustrated. We demonstrate numerically the influence of initial conditions on the mixing rate. Both the dominant short wavelength initial conditions and long wavelength perturbations are observed to play a role. By examination of two classes of experiments, we observe the absence of a single universal explanation, with long and short wavelength initial conditions, and the various physical and numerical regularizations contributing in different proportions in these two different contexts. PMID:20615983
Rayleigh--Taylor spike evaporation
Schappert, G. T.; Batha, S. H.; Klare, K. A.; Hollowell, D. E.; Mason, R. J.
2001-09-01
Laser-based experiments have shown that Rayleigh--Taylor (RT) growth in thin, perturbed copper foils leads to a phase dominated by narrow spikes between thin bubbles. These experiments were well modeled and diagnosed until this '' spike'' phase, but not into this spike phase. Experiments were designed, modeled, and performed on the OMEGA laser [T. R. Boehly, D. L. Brown, R. S. Craxton , Opt. Commun. 133, 495 (1997)] to study the late-time spike phase. To simulate the conditions and evolution of late time RT, a copper target was fabricated consisting of a series of thin ridges (spikes in cross section) 150 {mu}m apart on a thin flat copper backing. The target was placed on the side of a scale-1.2 hohlraum with the ridges pointing into the hohlraum, which was heated to 190 eV. Side-on radiography imaged the evolution of the ridges and flat copper backing into the typical RT bubble and spike structure including the '' mushroom-like feet'' on the tips of the spikes. RAGE computer models [R. M. Baltrusaitis, M. L. Gittings, R. P. Weaver, R. F. Benjamin, and J. M. Budzinski, Phys. Fluids 8, 2471 (1996)] show the formation of the '' mushrooms,'' as well as how the backing material converges to lengthen the spike. The computer predictions of evolving spike and bubble lengths match measurements fairly well for the thicker backing targets but not for the thinner backings.
Woltjer-Taylor State Without Taylor's Conjecture - Plasma Relaxation at all Wavelengths
Qin, Hong; Liu, Wandong; Li, Hong; Squire, Jonathan
2012-10-10
In astrophysical and laboratory plasmas, it has been discovered that plasmas relax towards the well-known Woltjer-Taylor state specified by ∇ x B = αB for a constant α . To explain how such a relaxed state is reached, Taylor developed his famous relaxation theory based on the conjecture that the relaxation is dominated by short wavelength fluctuations. However, there is no conclusive experimental and numerical evidence to support Taylor's conjecture. A new theory is developed, which predicts that the system will evolve towards the Woltjer-Taylor state for an arbitrary fluctuation spectrum.
Rayleigh-Taylor mixing in supernova experiments
NASA Astrophysics Data System (ADS)
Swisher, N. C.; Kuranz, C. C.; Arnett, D.; Hurricane, O.; Remington, B. A.; Robey, H. F.; Abarzhi, S. I.
2015-10-01
We report a scrupulous analysis of data in supernova experiments that are conducted at high power laser facilities in order to study core-collapse supernova SN1987A. Parameters of the experimental system are properly scaled to investigate the interaction of a blast-wave with helium-hydrogen interface, and the induced Rayleigh-Taylor instability and Rayleigh-Taylor mixing of the denser and lighter fluids with time-dependent acceleration. We analyze all available experimental images of the Rayleigh-Taylor flow in supernova experiments and measure delicate features of the interfacial dynamics. A new scaling is identified for calibration of experimental data to enable their accurate analysis and comparisons. By properly accounting for the imprint of the experimental conditions, the data set size and statistics are substantially increased. New theoretical solutions are reported to describe asymptotic dynamics of Rayleigh-Taylor flow with time-dependent acceleration by applying theoretical analysis that considers symmetries and momentum transport. Good qualitative and quantitative agreement is achieved of the experimental data with the theory and simulations. Our study indicates that in supernova experiments Rayleigh-Taylor flow is in the mixing regime, the interface amplitude contributes substantially to the characteristic length scale for energy dissipation; Rayleigh-Taylor mixing keeps order.
Rayleigh-Taylor mixing in supernova experiments
Swisher, N. C.; Abarzhi, S. I.; Kuranz, C. C.; Arnett, D.; Hurricane, O.; Remington, B. A.; Robey, H. F.
2015-10-15
We report a scrupulous analysis of data in supernova experiments that are conducted at high power laser facilities in order to study core-collapse supernova SN1987A. Parameters of the experimental system are properly scaled to investigate the interaction of a blast-wave with helium-hydrogen interface, and the induced Rayleigh-Taylor instability and Rayleigh-Taylor mixing of the denser and lighter fluids with time-dependent acceleration. We analyze all available experimental images of the Rayleigh-Taylor flow in supernova experiments and measure delicate features of the interfacial dynamics. A new scaling is identified for calibration of experimental data to enable their accurate analysis and comparisons. By properly accounting for the imprint of the experimental conditions, the data set size and statistics are substantially increased. New theoretical solutions are reported to describe asymptotic dynamics of Rayleigh-Taylor flow with time-dependent acceleration by applying theoretical analysis that considers symmetries and momentum transport. Good qualitative and quantitative agreement is achieved of the experimental data with the theory and simulations. Our study indicates that in supernova experiments Rayleigh-Taylor flow is in the mixing regime, the interface amplitude contributes substantially to the characteristic length scale for energy dissipation; Rayleigh-Taylor mixing keeps order.
Temperature, size, and depth of the magma reservoir for the Taylor Creek Rhyolite, New Mexico
Duffield, W.A.; du Bray, E.A.
1990-01-01
The 55 km3 mid-Tertiary Taylor Creek Rhyolite in southwestern New Mexico consists of 20 lava domes and flows. This rhyolite is metaluminous to weakly peraluminous. Compositional zonation in feldspar phenocrysts is very minor and nonsystematic. The compositions of each feldspar species vary little throughout the suite of analyzed samples. This chemical homogeneity of phenocrysts reflects similar whole-rock homogeneity and suggests that the lavas were tapped from a single large reservoir of magma. Ages of sanidine phenocrysts determined using 40Ar/39Ar indicate that the Taylor Creek Rhyolite lavas were emplaced during a period of less than 0.42 my. and possibly less than 0.13 m.y., which is consistent with the single-reservoir scenario. Two-feldspar geothermometry suggests that Taylor Creek Rhyolite phenocrysts crystallized at about 775??C, at an assumed pressure of 2 kbar. Fe-Ti-oxide geothermometry suggests phenocryst growth at about 800??C. Experimental studies suggest that quartz and potassium-feldspar crystals that grow from H2O-undersaturated granitic magmas should exhibit resorption texture, a texture ubiquitous to Taylor Creek Rhyolite quartz and sanidine phenocrysts. We tentatively conclude that the Taylor Creek Rhyolite magma was H2O undersaturated and subliquidus at an unspecified pressure greater than 0.5 kbar during phenocryst growth and that Taylor Creek Rhyolite pyroclastic deposits formed because volatile saturation developed during the ascent of magma to sites of eruption. -from Authors
New directions for Rayleigh-Taylor mixing.
Glimm, James; Sharp, David H; Kaman, Tulin; Lim, Hyunkyung
2013-11-28
We study the Rayleigh-Taylor (RT) mixing layer, presenting simulations in agreement with experimental data. This problem is an idealized subproblem of important scientific and engineering problems, such as gravitationally induced mixing in oceanography and performance assessment for inertial confinement fusion. Engineering codes commonly achieve correct simulations through the calibration of adjustable parameters. In this sense, they are interpolative and not predictive. As computational science moves from the interpolative to the predictive and reduces the reliance on experiment, the quality of decision making improves. The diagnosis of errors in a multi-parameter, multi-physics setting is daunting, so we address this issue in the proposed idealized setting. The validation tests presented are thus a test for engineering codes, when used for complex problems containing RT features. The RT growth rate, characterized by a dimensionless but non-universal parameter α, describes the outer edge of the mixing zone. Increasingly accurate front tracking/large eddy simulations reveal the non-universality of the growth rate and agreement with experimental data. Increased mesh resolution allows reduction in the role of key subgrid models. We study the effect of long-wavelength perturbations on the mixing growth rate. A self-similar power law for the initial perturbation amplitudes is here inferred from experimental data. We show a maximum ±5% effect on the growth rate. Large (factors of 2) effects, as predicted in some models and many simulations, are inconsistent with the experimental data of Youngs and co-authors. The inconsistency of the model lies in the treatment of the dynamics of bubbles, which are the shortest-wavelength modes for this problem. An alternative theory for this shortest wavelength, based on the bubble merger model, was previously shown to be consistent with experimental data. PMID:24146006
Cathedral house & crocker fence, Taylor Street east and north ...
Cathedral house & crocker fence, Taylor Street east and north elevations, perspective view from the northeast - Grace Cathedral, George William Gibbs Memorial Hall, 1051 Taylor Street, San Francisco, San Francisco County, CA
20. TURNTABLE WITH CABLE CAR BAY & TAYLOR: View ...
20. TURNTABLE WITH CABLE CAR - BAY & TAYLOR: View to northwest of the Bay and Taylor turntable. The gripman and conductor are turning the car around. - San Francisco Cable Railway, Washington & Mason Streets, San Francisco, San Francisco County, CA
Neo-Taylorism in Educational Administration?
ERIC Educational Resources Information Center
Gronn, Peter C.
1982-01-01
Reviews eight recent observational studies of school administrators and criticizes the studies' use of "time and motion" assumptions drawn from Frederick Winslow Taylor's ideas. Outlines an alternate approach based on "thick" description of administrators' work, including their talk, as exemplified in James Boswell's biography of Samuel Johnson.…
Damage modeling for Taylor impact simulations
NASA Astrophysics Data System (ADS)
Anderson, C. E., Jr.; Chocron, I. S.; Nicholls, A. E.
2006-08-01
G. I. Taylor showed that dynamic material properties could be deduced from the impact of a projectile against a rigid boundary. The Taylor anvil test became very useful with the advent of numerical simulations and has been used to infer and/or to validate material constitutive constants. A new experimental facility has been developed to conduct Taylor anvil impacts to support validation of constitutive constants used in simulations. Typically, numerical simulations are conducted assuming 2-D cylindrical symmetry, but such computations cannot hope to capture the damage observed in higher velocity experiments. A computational study was initiated to examine the ability to simulate damage and subsequent deformation of the Taylor specimens. Three-dimensional simulations, using the Johnson-Cook damage model, were conducted with the nonlinear Eulerian wavecode CTH. The results of the simulations are compared to experimental deformations of 6061-T6 aluminum specimens as a function of impact velocity, and conclusions regarding the ability to simulate fracture and reproduce the observed deformations are summarized.
PEOPLE IN PHYSICS: Interview with Charles Taylor
NASA Astrophysics Data System (ADS)
Pople, Conducted by Stephen
1996-07-01
Charles Taylor started his university teaching career at UMIST in 1948. In 1965 he became Professor and Head of the Department of Physics at University College, Cardiff. He was a Vice-President of the Institute of Physics from 1970 to 1975, and Professor of Experimental Physics at the Royal Institution from 1977 until 1989. Over the years, Professor Taylor has delighted audiences of all ages with his demonstration lectures, including the Royal Institution Christmas Lectures televised in 1971 and 1989. In 1986 he became the first recipient of the Royal Society's Michael Faraday Award for contributions to the public understanding of science. His many books include Exploring Music, The Art and Science of the Lecture Demonstration, and also the Oxford Children's Book of Science, co-written with interviewer Stephen Pople.
CTH simulation of PBX-9501 Taylor tests /
Koby, Joseph R.
2011-09-01
During March-May 2011, multiple Taylor impact tests were conducted at LANL, examining the behavior of PBXN-9 and PBX-9501 under rapid loading. Subsequently, a computational hydrodynamics code (CTH) model was developed to mimic the deformation behavior observed in these impact tests with PBX-9501 would likely initiate upon impact. Also examined was whether an inert slud behind the explosive would lead to initiation at lower, more easily attainable velocities. The simplified model used here showed a minimum velocity for ignition of 530 m/s which was unchanged by the addition of a plastic slud behind the sample. The use of a lead slug did lower the minimum velocity to 460 m/s. These values are likely more qualitative at this point because multiple simplifications are currently used in the materials properties and test geometry. The results do show that this approach is capable of determining ignition due to Taylor impact.
Rayleigh-Taylor Mix experiment on Pegasus
Sheppard, M.G.; Atchison, W.L.; Anderson, W.E.
1997-09-01
The Rayleigh-Taylor Mix project will attempt to diagnose and understand the growth of a mixing layer at the interface between an imploding metal liner and a polystyrene foam core in a series of pulsed power experiments on the Pegasus capacitor bank. Understanding the effects of material strength will be an important part of the study. During the initial phase of the implosion, the linear/foam interface is Rayleigh-Taylor (RT) stable; however, as the foam is compressed, it decelerates the liner, causing it to bound and to go RT unstable. This paper reports 1D and 2D MHD simulations of the first experiment in the series and preliminary results.
New trends in Taylor series based applications
NASA Astrophysics Data System (ADS)
Kocina, Filip; Šátek, Václav; Veigend, Petr; Nečasová, Gabriela; Valenta, Václav; Kunovský, Jiří
2016-06-01
The paper deals with the solution of large system of linear ODEs when minimal comunication among parallel processors is required. The Modern Taylor Series Method (MTSM) is used. The MTSM allows using a higher order during the computation that means a larger integration step size while keeping desired accuracy. As an example of complex systems we can take the Telegraph Equation Model. Symbolic and numeric solutions are compared when harmonic input signal is used.
1989 Bowen Award to Ross Taylor
NASA Astrophysics Data System (ADS)
Burke, Kevin
Ross Taylor graduated with a B.Sc. degree from Canterbury College of the then University of New Zealand in 1948 and an M.Sci in 1951. He followed the footsteps of Ernest Rutherford and other distinguished New Zealanders (including a surprisingly large number of AGU Fellows in proportion to the small population of New Zealand) by going aboard to further pursue his scientific education.
Fluctuation scaling, Taylor's law, and crime.
Hanley, Quentin S; Khatun, Suniya; Yosef, Amal; Dyer, Rachel-May
2014-01-01
Fluctuation scaling relationships have been observed in a wide range of processes ranging from internet router traffic to measles cases. Taylor's law is one such scaling relationship and has been widely applied in ecology to understand communities including trees, birds, human populations, and insects. We show that monthly crime reports in the UK show complex fluctuation scaling which can be approximated by Taylor's law relationships corresponding to local policing neighborhoods and larger regional and countrywide scales. Regression models applied to local scale data from Derbyshire and Nottinghamshire found that different categories of crime exhibited different scaling exponents with no significant difference between the two regions. On this scale, violence reports were close to a Poisson distribution (α = 1.057 ± 0.026) while burglary exhibited a greater exponent (α = 1.292 ± 0.029) indicative of temporal clustering. These two regions exhibited significantly different pre-exponential factors for the categories of anti-social behavior and burglary indicating that local variations in crime reports can be assessed using fluctuation scaling methods. At regional and countrywide scales, all categories exhibited scaling behavior indicative of temporal clustering evidenced by Taylor's law exponents from 1.43 ± 0.12 (Drugs) to 2.094 ± 0081 (Other Crimes). Investigating crime behavior via fluctuation scaling gives insight beyond that of raw numbers and is unique in reporting on all processes contributing to the observed variance and is either robust to or exhibits signs of many types of data manipulation. PMID:25271781
ERIC Educational Resources Information Center
Woody, Erik Z.; Szechtman, Henry
2005-01-01
In response to commentary by S. Taylor, D. McKay, and J. S. Abramowitz, the authors discuss the distinctive features of their theory of obsessive-compulsive disorder outlined in their original article, which explains the disorder as a dysfunction of a security-motivation system. The authors address issues of the interrelation of emotion,…
Microbial Energetics Beneath the Taylor Glacier, Antarctica
NASA Astrophysics Data System (ADS)
Mikucki, J. A.; Turchyn, A. V.; Farquhar, J.; Priscu, J. C.; Schrag, D. P.; Pearson, A.
2007-12-01
Subglacial microbiology is controlled by glacier hydrology, bedrock lithology, and the preglacial ecosystem. These factors can all affect metabolic function by influencing electron acceptor and donor availability in the subglacial setting leaving biogeochemical signatures that can be used to determine ecosystem processes. Blood Falls, an iron-rich, episodic subglacial outflow from the Taylor Glacier in the McMurdo Dry Valleys Antarctica provides an example of how microbial community structure and function can provide insight into subglacial hydrology. This subglacial outflow contains cryoconcentrated, Pliocene-age seawater salts that pooled in the upper Taylor Valley and was subsequently covered by the advance of the Taylor Glacier. Biogeochemical measurements, culture-based techniques, and genomic analysis were used to characterize microbes and chemistry associated with the subglacial outflow. The isotopic composition of important geochemical substrates (i.e., δ34Ssulfate, Δ33Ssulfate, δ18Osulfate, δ18Owater, Δ14SDIC) were also measured to provide more detail on subglacial microbial energetics. Typically, subglacial systems, when driven to anoxia by the hydrolysis of organic matter, will follow a continuum of redox chemistries utilizing electron acceptors with decreasing reduction potential (e.g., Fe (III), sulfate, CO2). Our data provide no evidence for sulfate reduction below the Taylor Glacier despite high dissolved organic carbon (450 μM C) and measurable metabolic activity. We contend that, in the case of the Taylor Glacier, the in situ bioenergetic reduction potential has been 'short-circuited' at Fe(III)-reduction and excludes sulfate reduction and methanogenesis. Given the length of time that this marine system has been isolated from phototrophic production (~2 Mya) the ability to degrade and consume increasingly recalcitrant organic carbon is likely an important component to the observed redox chemistry. Our work indicates that glacier hydrology
Rayleigh-Taylor instability in binary condensates
Gautam, S.; Angom, D.
2010-05-15
We propose a well-controlled experimental scheme to initiate and examine the Rayleigh-Taylor instability in two-species Bose-Einstein condensates. We identify the {sup 85}Rb-{sup 87}Rb mixture as an excellent candidate to observe experimentally. The instability is initiated by tuning the {sup 85}Rb-{sup 85}Rb interaction through a magnetic Feshbach resonance. We show that the observable signature of the instability is the damping of the radial oscillations. We also propose a semianalytic scheme to determine the stationary state of binary condensates with the Thomas-Fermi approximation for axisymmetric traps.
Monitoring Biopolymer Degradation by Taylor Dispersion Analysis.
Chamieh, Joseph; Biron, Jean Philippe; Cipelletti, Luca; Cottet, Hervé
2015-12-14
This work aims at demonstrating the interest of modern Taylor dispersion analysis (TDA), performed in narrow internal diameter capillary, for monitoring biopolymer degradations. Hydrolytic and enzymatic degradations of dendrigraft poly-l-lysine taken as model compounds have been performed and monitored by TDA at different degradation times. Different approaches for the data processing of the taylorgrams are compared, including simple integration of the taylorgram, curve fitting with a finite number of Gaussian peaks, cumulant-like method and Constrained Regularized Linear Inversion approach. Valuable information on the kinetics of the enzymatic/hydrolytic degradation reactions and on the degradation process can be obtained by TDA. PMID:26633075
Hydrodynamical Dispersion in Taylor-Couette Cells
NASA Astrophysics Data System (ADS)
Piva, M.; Calvo, A.; Aguirre, A.; Callegari, G.; Gabbanelli, S.; Rosen, M.; Wesfreid, J. E.
1997-04-01
In this article we study the mass tracer dispersion in organized flows. For this purpose we performed experiments in the flow arising from the Taylor-Couette hydrodynamic instability combined with axial flow. The tracer evolution is followed by means of optical measurements of the concentration. In this way transmission curves are obtained. We compare these curves with the solutions of the Gaussian models of mass diffusion and with phenomenological models including tracer trapping in the cells. This comparison gives us physical parameters related to the typical time and distances involved in the diffusive behaviour of tracers in the regions with recirculations and trapping.
Ekman and Taylor Vortices' Destruction and Mixing Enhancement in a Taylor-Couette System
NASA Astrophysics Data System (ADS)
Oualli, H.; Mekadem, M.; Bentsabet, A.; Abada, M.; Bouabdallah, A.; Gad-El-Hak, M.
2014-11-01
Suppression of Ekman and Taylor vortices is sought in several industrial processes such as cylindrical crystal growth and osmotic/photonic water purification. Last meeting, we investigated experimentally and numerically an active flow control strategy to obliterate vortices in a Taylor-Couette flow. The control consists of effecting minute radial pulsatile motion of the rotating inner cylinder's cross-section. The results showed that destruction of either type of vortices occurs at different pulsatile frequencies, requiring one order of magnitude higher frequency to obliterate the Ekman type. This problem is revisited with identical parameters and conditions for the controlling strategy but the Taylor-Couette system is now inclined relative to the horizontal direction in such a way that gravitational effects are no longer negligible. It is found that body forces contribute to the complete destruction of Taylor and Ekman vortices, reducing the optimum frequency by more than 50% for even a modest inclination angle of θ =15° . Furthermore, the axial and azimuthal velocity fluctuations are increased by one order of magnitude, thus yielding substantial enhancement in flow mixing.
Axially localized states in Taylor Couette flows
NASA Astrophysics Data System (ADS)
Lopez, Jose M.; Marques, Francisco
2014-11-01
We present numerical simulations of the flow in a Taylor Couette system with the inner cylinder rotating and aspect ratio Γ restricted to 0 . 86 <Γ/N < 0 . 95 , being N the number of Taylor vortices. For these values a complex experimental bifurcation scenario has been reported. The transition from wavy vortex flow (WVF) to a very low frequency mode VLF happens via an axisymmetric eigenfunction. The VLF plays an essential role in the dynamics, leading to chaos through a two-tori period-doubling route. This chaotic regime vanishes with further increase in Re and gives rise to a new flow regime ALS characterized by the existence of large jet oscillations localized in some pairs of vortices. The aim of this numerical study is to extend the available information on ALS by means of a detailed exploration of the parameter space in which it occurs. Frequency analysis from time series simultaneously recorded at several points of the domain has been applied to identify the different transitions taking place. The VLF occurs in a wide range of control parameters and its interaction with the axially localized states is crucial is most transitions, either between different ALS or to the chaotic regime. Spanish Ministry of Education and Science Grants (with FEDER funds) FIS2013-40880 and BES-2010-041542.
A cosmological Slavnov-Taylor identity
NASA Astrophysics Data System (ADS)
Collins, Hael; Holman, R.; Vardanyan, Tereza
2014-12-01
We develop a method for treating the consistency relations of inflation that includes the full time-evolution of the state. This approach relies only on the symmetries of the inflationary setting, in particular a residual conformal symmetry in the spatial part of the metric, along with general properties which hold for any quantum field theory. As a result, the consistency relations that emerge, which are essentially the Slavnov-Taylor identities associated with this residual conformal symmetry, apply very generally: they are true of the full Green's functions, hold largely independently of the particular inflationary model, and can be used for arbitrary states. We illustrate these techniques by showing the form assumed by the standard consistency relation between the two and three-point functions for the primordial scalar fluctuations when they are in a Bunch-Davies state. But because we have included the full evolution of the state, this approach works for a general initial state as well and does not need to have assumed that inflation began in the Bunch-Davies state. We explain how the Slavnov-Taylor identity is modified for these more general states.
Evaluating a Class of Series Using Taylor's Theorem. Classroom Notes
ERIC Educational Resources Information Center
Glaister, P.
2004-01-01
A class of infinite series is evaluated with the aid of Taylor's theorem and a comparison is made with other methods. In a recent note [1] a class of infinite series was shown to be equivalent to a number of definite integrals, and Taylor's theorem was used to establish convergence and to determine the sums of the series and the integrals to any…
78 FR 12307 - Taylor, G. Tom; Notice of Filing
Federal Register 2010, 2011, 2012, 2013, 2014
2013-02-22
... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Taylor, G. Tom; Notice of Filing Take notice that on February 14, 2013, G. Tom Taylor filed an application to hold interlocking positions pursuant to section 305(b) of...
15. TURNTABLE RECONSTRUCTION BAY & TAYLOR: Photocopy of January ...
15. TURNTABLE RECONSTRUCTION - BAY & TAYLOR: Photocopy of January 1941 photograph taken during reconstruction of the Bay and Taylor turntable. View to the south. The 'spider' that carries the actual turntable is in place in the pit. - San Francisco Cable Railway, Washington & Mason Streets, San Francisco, San Francisco County, CA
G.I. Taylor and the Trinity Test
ERIC Educational Resources Information Center
Deakin, Michael A. B.
2011-01-01
The story is often told of the calculation by G.I. Taylor of the yield of the first ever atomic bomb exploded in New Mexico in 1945. It has indeed become a staple of the classroom whenever dimensional analysis is taught. However, while it is true that Taylor succeeded in calculating this figure at a time when it was still classified, most versions…
Animating Nested Taylor Polynomials to Approximate a Function
ERIC Educational Resources Information Center
Mazzone, Eric F.; Piper, Bruce R.
2010-01-01
The way that Taylor polynomials approximate functions can be demonstrated by moving the center point while keeping the degree fixed. These animations are particularly nice when the Taylor polynomials do not intersect and form a nested family. We prove a result that shows when this nesting occurs. The animations can be shown in class or…
Modeling Solid Rayleigh-Taylor Growth
Kaul, Ann M
2010-09-20
Intense impulses applied to solid materials result in high strain rates, strong plastic strains and significant temperature increments. Data in such regimes would allow confidence in extending material strength models to strain rates of 10{sup 6}-10{sup 7} s{sup -1}. High explosives can be used to accelerate a plate with a perturbation on the side facing the HE, resulting in a Rayleigh-Taylor-like perturbation growth that depends on amplitude and wavelength of the initial surface perturbation, strength of the material, time dependence of the driving pressure force, and temperature of the material. Such experiments have been conducted on perturbed copper plates at LANL, using the LANSCE proton radiography beam to obtain multiple frames of data for each experiment. The results of numerical simulations of these experiments using a 2-D ALE code are presented.
Rayleigh-Taylor instability in elastic solids.
Piriz, A R; Cela, J J López; Cortázar, O D; Tahir, N A; Hoffmann, D H H
2005-11-01
We present an analytical model for the Rayleigh-Taylor instability that allows for an approximate but still very accurate and appealing description of the instability physics in the linear regime. The model is based on the second law of Newton and it has been developed with the aim of dealing with the instability of accelerated elastic solids. It yields the asymptotic instability growth rate but also describes the initial transient phase determined by the initial conditions. We have applied the model to solid/solid and solid/fluid interfaces with arbitrary Atwood numbers. The results are in excellent agreement with previous models that yield exact solutions but which are of more limited validity. Our model allows for including more complex physics. In particular, the present approach is expected to lead to a more general theory of the instability that would allow for describing the transition to the plastic regime. PMID:16383751
Classical Rayleigh Taylor experiments on Nova
Budil, K.S.; Remington, B.A.; Peyser, T.A.
1995-07-01
The evolution of the Rayleigh-Taylor (RT) instability in a compressible medium was investigated both at an accelerating embedded interface and at the ablation front in a new series of experiments on Nova. The x-ray drive generated in a hohlraum ablatively accelerated a planar target consisting of a doped plastic pusher which was in some cases backed by a higher density titanium payload. Both target types were diagnosed by face-on and side-on radiography. Experiments have been done with a variety of wavelengths and initial amplitudes. In the case where the perturbed RT-unstable embedded interface is isolated from the ablation front, short wavelength perturbations are observed to grow strongly. When the perturbation is at the ablation front, the short wavelengths are observed to be severely stabilized.
Anelastic Rayleigh–Taylor mixing layers
NASA Astrophysics Data System (ADS)
Schneider, N.; Gauthier, S.
2016-07-01
Anelastic Rayleigh–Taylor mixing layers for miscible fluids are investigated with a recently built model (Schneider and Gauthier 2015 J. Eng. Math. 92 55–71). Four Chebyshev–Fourier–Fourier direct numerical simulations are analyzed. They use different values for the compressibility parameters: Atwood number (the dimensionless difference of the heavy and light fluid densities) and stratification (accounts for the vertical variation of density due to gravity). For intermediate Atwood numbers and finite stratification, compressibility effects quickly occurs. As a result only nonlinear behaviours are reached. The influence of the compressibility parameters on the growth speed of the RTI is discussed. The 0.1—Atwood number/0.4—stratification configuration reaches a turbulent regime. This turbulent mixing layer is analyzed with statistical tools such as moments, PDFs, anisotropy indicators and spectra.
Aluminum Rayleigh Taylor Strength Measurements and Calculations
Lindquist, M J; Cavallo, R M; Lorenz, K T; Pollaine, S M; Remington, B A; Raevsky, V A
2007-01-10
A traditional approach to the study of material strength has been revitalized at the Russian Federal Nuclear Center (VNIIEF). Rayleigh Taylor strength experiments have long been utilized to measure the material response of metals at high pressure and strain rates. A modulated (sinusoidal or sawtooth perturbation) surface is shocklessly (quasi-isentropically) accelerated by a high explosive (HE) driver, and radiography is used to measure the perturbation amplitude as a function of time. The Aluminum T-6061 targets are designed with several sets of two-dimensional sawtooth perturbations machined on the loading surface. The HE driver was designed to reach peak pressures in the range of 200 to 300 kbar and strain rates in the range of 10{sup 4} - 10{sup 6} s{sup -1}. The standard constitutive strength models, Steinberg-Guinan (SG) [1], Steinberg-Lund (SL) [2], Preston-Tonks-Wallace (PTW) [3], Johnson-Cooke (JC) [4], and Mechanical Threshold Stress (MTS) [5], have been calibrated by traditional techniques: (Hopkinson-Bar, Taylor impact, flyer plate/shock-driven experiments). The VNIIEF experimental series accesses a strain rate regime not attainable using traditional methods. We have performed a detailed numerical study with a two-dimensional Arbitrary Lagrangian Eulerian hydrodynamics computer code containing several constitutive strength models to predict the perturbation growth. Results show that the capabilities of the computational methodology predict the amplitude growth to within 5 percent of the measured data, thus validating both the code and the strength models under the given conditions and setting the stage for credible future design work using different materials.
The solution of the point kinetics equations via converged accelerated Taylor series (CATS)
Ganapol, B.; Picca, P.; Previti, A.; Mostacci, D.
2012-07-01
This paper deals with finding accurate solutions of the point kinetics equations including non-linear feedback, in a fast, efficient and straightforward way. A truncated Taylor series is coupled to continuous analytical continuation to provide the recurrence relations to solve the ordinary differential equations of point kinetics. Non-linear (Wynn-epsilon) and linear (Romberg) convergence accelerations are employed to provide highly accurate results for the evaluation of Taylor series expansions and extrapolated values of neutron and precursor densities at desired edits. The proposed Converged Accelerated Taylor Series, or CATS, algorithm automatically performs successive mesh refinements until the desired accuracy is obtained, making use of the intermediate results for converged initial values at each interval. Numerical performance is evaluated using case studies available from the literature. Nearly perfect agreement is found with the literature results generally considered most accurate. Benchmark quality results are reported for several cases of interest including step, ramp, zigzag and sinusoidal prescribed insertions and insertions with adiabatic Doppler feedback. A larger than usual (9) number of digits is included to encourage honest benchmarking. The benchmark is then applied to the enhanced piecewise constant algorithm (EPCA) currently being developed by the second author. (authors)
Author! Author! Beverly Cleary
ERIC Educational Resources Information Center
Brodie, Carolyn S.
2005-01-01
This article presents a brief biography of author Beverly Cleary. Born on April 12, 1916 in McMinnville, Oregon (Yamhill County), Beverly Cleary celebrated her eighty-ninth birthday in 2005. Cleary is probably best known for creating "Ramona" and the other children's book characters who live on Klickitat Street in Portland, Oregon. A selective…
Kinetic Simulations of Rayleigh-Taylor Instabilities
NASA Astrophysics Data System (ADS)
Sagert, Irina; Bauer, Wolfgang; Colbry, Dirk; Howell, Jim; Staber, Alec; Strother, Terrance
2014-09-01
We report on an ongoing project to develop a large scale Direct Simulation Monte Carlo code. The code is primarily aimed towards applications in astrophysics such as simulations of core-collapse supernovae. It has been tested on shock wave phenomena in the continuum limit and for matter out of equilibrium. In the current work we focus on the study of fluid instabilities. Like shock waves these are routinely used as test-cases for hydrodynamic codes and are discussed to play an important role in the explosion mechanism of core-collapse supernovae. As a first test we study the evolution of a single-mode Rayleigh-Taylor instability at the interface of a light and a heavy fluid in the presence of a gravitational acceleration. To suppress small-wavelength instabilities caused by the irregularity in the separation layer we use a large particle mean free path. The latter leads to the development of a diffusion layer as particles propagate from one fluid into the other. For small amplitudes, when the instability is in the linear regime, we compare its position and shape to the analytic prediction. Despite the broadening of the fluid interface we see a good agreement with the analytic solution. At later times we observe the development of a mushroom like shape caused by secondary Kelvin-Helmholtz instabilities as seen in hydrodynamic simulations and consistent with experimental observations.
Numerical Simulation of Taylor Cone-Jet
NASA Astrophysics Data System (ADS)
Toledo, Ronne
The Taylor cone-jet is a particular type of electrohydrodynamic phenomenon where electrostatic stresses and surface tension effects shape the interface of the jet in a peculiar conical shape. A thin jet is issued from the cone apex that further breaks up into a fine aerosol. Due to its monodispersive properties, this fine aerosol has found a number of applications, ranging from mass spectrometry, colloidal space propulsion, combustion, nano-fabrication, coating/painting, and many others. In this study, a general non-dimensional analysis is performed to derive the governing equations and boundary conditions. In accordance with the observations of Gamero-Castano (2010), noting that droplet electric potential is insensitive to the flow rate conditions, a particular set of characteristic parameters is proposed, based on the terminal jet diameter. In order to solve the non-dimensional set of governing equations and boundary conditions, a numerical method combining the Boundary Element Method and the Finite Volume Method is developed. Results of electric current have shown good agreement with numerical and experimental data available in the literature. The main feature of the algorithm developed is related to the decoupling of the electrostatic from the hydrodynamic problem, allowing us to accurately prescribe the far field electric potential boundary conditions away from the hydrodynamic computational domain used to solve the hydrodynamics of the transition region near the cone apex.
Slavnov-Taylor identities for primordial perturbations
Berezhiani, Lasha; Khoury, Justin E-mail: jkhoury@sas.upenn.edu
2014-02-01
Correlation functions of adiabatic modes in cosmology are constrained by an infinite number of consistency relations, which relate N + 1-point correlation functions with a soft-momentum scalar or tensor mode to a symmetry transformation on N-point correlation functions of hard-momentum modes. They constrain, at each order n, the q{sup n} behavior of the soft limits. In this paper we show that all consistency relations derive from a single, master identity, which follows from the Slavnov-Taylor identity for spatial diffeomorphisms. This master identity is valid at any value of q and therefore goes beyond the soft limit. By differentiating it n times with respect to the soft momentum, we recover the consistency relations at each q order. Our approach underscores the role of spatial diffeomorphism invariance at the root of cosmological consistency relations. It also offers new insights on the necessary conditions for their validity: a physical contribution to the vertex functional must satisfy certain analyticity properties in the soft limit in order for the consistency relations to hold. For standard inflationary models, this is equivalent to requiring that mode functions have constant growing-mode solutions. For more exotic models in which modes do not ''freeze'' in the usual sense, the analyticity requirement offers an unambiguous criterion.
Rayleigh-Taylor mixing in supernova experiments
NASA Astrophysics Data System (ADS)
Swisher, Nora; Kuranz, Carolyn; Arnett, David; Hurricane, Omar; Remington, Bruce; Robey, Harry; Abarzhi, Snezhana
2015-11-01
We report a scrupulous analysis of data in supernova experiments that are conducted at high power laser facilities in order to study core-collapse supernova SN1987A. Parameters of the experimental system are properly scaled to investigate the interaction of a blast-wave with helium-hydrogen interface, and the induced Rayleigh-Taylor (RT) mixing of the denser and lighter fluids with time-dependent acceleration. We analyze all available experimental images of RT flow in supernova experiments, and measure delicate features of the interfacial dynamics. A new scaling is identified for calibration of experimental data to enable their accurate analysis and comparisons. By proper accounting for the imprint of the experimental conditions, the data set size and statistics are substantially increased. New theoretical solutions are identified to describe asymptotic dynamics of RT flow with time-dependent acceleration by applying theoretical analysis. Good qualitative and quantitative agreement is achieved of the experimental data with the theory and simulations. Our study indicates that in supernova experiments, the RT flow is in the mixing regime, the interface amplitude contributes substantially to the characteristic length scale for energy dissipation; the mixing flow may keep order. Support of the National Science Foundation is warmly appreciated.
Janet Taylor Spence (1923-2015).
Deaux, Kay
2016-01-01
The long and remarkable life of Janet Taylor Spence, the sixth woman to serve as president of the American Psychological Association (APA), ended on March 16, 2015, after a short illness. Janet's 1978 book, Masculinity & Femininity, coauthored with Robert Helmreich, was a major contribution to our understanding of the complex relationships between personal attributes, self-esteem, and attitudes toward women, as well their links to both achievement motivation and parental characteristics. Janet's interest in achievement motivation was an extension of her gender work, as she attempted to learn more about the ways in which presumed differences in achievement motivation might be related to the key dimensions of instrumentality and expressiveness. Janet's election to the presidency of the APA was the culmination of a long and broad involvement in the organization. She served on the Board of Directors from 1976 to 1978, and again in 1983 to 1984 during her presidential term. Earlier she served on the Board of Scientific Affairs and edited Contemporary Psychology in the 1970s. Janet was a fellow in four divisions (3, 8, 12, and 35), and in 2004 she received the APA Gold Medal Award for Life Achievement in the Science of Psychology. PMID:26766767
Experimental determination of the effective Taylor dispersivity in a fracture
Gilardi, J.R.
1984-06-01
The applicability and accuracy of the approximation for Taylor Dispersion was experimentally determined for the diffusion of a chemical tracer in flow through a fracture. 12 refs., 16 figs., 10 tabs. (ACR)
McMurdo LTER: streamflow measurements in Taylor Valley
McKnight, D.; House, H.; Von Guerard, P.
1994-01-01
Has established a stream gaging network for the three major lake basins in Taylor Valley. These data are critical for determining nutrient budgets for the lake ecosystems and for understanding physical factors controlling microbial mats in the streams.
ChuckTaylor: Principal Investigator, Game Changing Development Program
Charles (Chuck) Taylor is the Principal Investigator in the Space Technology's Game Changing Development Program for 3 major projects:Solar Electric Propulsion, Ride The Light (RTL), and Space Powe...
The effect of scale on the applicability of Taylor's hypothesis
NASA Astrophysics Data System (ADS)
Parlange, Marc; Higgins, Chad; Froidevaux, Martin; Simeonov, Valentin
2010-05-01
Taylor's frozen flow hypothesis is a central assumption in most fluid mechanics experiments with stationary sensors, and many statistical theories of turbulence where links between the Lagrangian and Eulerian nature of turbulence are made. In this work we seek to quantify the effectiveness of Taylor's hypothesis at the field scale using water vapor as a passive tracer. A horizontal Raman Lidar is used to capture the humidity field in space and time above a small lake in Switzerland. High resolution wind speed and direction measurements are conducted simultaneously allowing for a direct test of Taylor's hypothesis. Through a wavelet decomposition of the data we show that scale has a strong influence on the applicability of Taylor's hypothesis. This effect is explained through the use of dimensional analysis and turbulent structure functions, which ultimately leads to the definition of a nondimensional parameter describing the ‘persistency' of the turbulence.
1. Historic American Buildings Survey Everitt K. Taylor, Photographer September ...
1. Historic American Buildings Survey Everitt K. Taylor, Photographer September 15, 1936 EXTERIOR - GENERAL VIEW EAST ELEVATION FROM OLD PRINT IN POSSESSION OF OWNER - Governor's House, 149 Kearny Avenue, Perth Amboy, Middlesex County, NJ
2. Historic American Buildings Survey Everitt K. Taylor, Photographer September ...
2. Historic American Buildings Survey Everitt K. Taylor, Photographer September 15, 1936 EXTERIOR - EAST ELEVATION FROM OLD PRINT IN POSSESSION OF OWNER - Governor's House, 149 Kearny Avenue, Perth Amboy, Middlesex County, NJ
Taylor impact tests and simulations of plastic bonded explosives
NASA Astrophysics Data System (ADS)
Clements, Brad E.; Thompson, Darla; Luscher, D. J.; DeLuca, Racci; Brown, Geoffrey
2012-03-01
Taylor impact tests were conducted on plastic bonded explosives PBX 9501 and PBXN-9 for impact velocities between 80 and 214 m/s. High-speed photography was used to image the impact event at a rate of one frame for every 25 μs. For early times, PBXN-9 showed large-deformation mushrooming of the explosive cylinders, followed by fragmentation by an amount proportional to the impact speed, was observed at all velocities. PBX 9501 appeared to be more brittle than PBXN-9, the latter demonstrated a more viscoelastic response. The post-shot fragments were collected and particle size distributions were obtained. The constitutive model ViscoSCRAM was then used to model the Taylor experiments using the finite element code ABAQUS. Prior to the Taylor simulations, ViscoSCRAM was parameterized for the two explosives using uniaxial stress-strain data. Simulating Taylor impact tests validates the model in situations undergoing extreme damage and fragmentation.
The New Taylorism: Hacking at the Philosophy of the University's End
ERIC Educational Resources Information Center
Goodman, Robin Truth
2012-01-01
This article looks at the critical writings of Mark C. Taylor. It suggests that Mark C. Taylor is rewriting a global imaginary devoid of the kind of citizenship that Henry Giroux claims as the basis for public education. Instead, Taylor wants to see the university take shape as profit-generating. According to Taylor, in lieu of learning to take…
Suppression of Rayleigh Taylor instability in strongly coupled plasmas
Das, Amita; Kaw, Predhiman
2014-06-15
The Rayleigh Taylor instability in a strongly coupled plasma medium has been investigated using the equations of generalized hydrodynamics. It is demonstrated that the visco-elasticity of the strongly coupled medium due to strong inter particle correlations leads to a suppression of the Rayleigh Taylor instability unless certain threshold conditions are met. The relevance of these results to experiments on laser compression of matter to high densities including those related to inertial confinement fusion using lasers has also been shown.
Observation of the Taylor instability in a dusty plasma
Pacha, K. A.; Heinrich, J. R.; Kim, S.-H.; Merlino, R. L.
2012-01-15
Observations of the Taylor instability in a laboratory dusty plasma are presented. The dust cloud, formed in a dc argon glow-discharge plasma, is stratified into regions of high and low dust densities. The instability was triggered by a spontaneous intrusion of the low density dust fluid into the high density dust fluid at the interface. The instability in the dust fluid was phenomenologically similar to the hydrodynamic Taylor instability that occurs when a light fluid is accelerated into a heavy fluid.
Generalized Saffman-Taylor formula for multi-layer Hele-Shaw flows
NASA Astrophysics Data System (ADS)
Daripa, Prabir
2011-03-01
Stability theory plays a major role from fundamental science to applied sciences. It is useful in the design of many processes and engineering instruments as well as in explaining many phenomena. In this paper we review some of the author's and his collaborator's recent works on the extension of Saffman-Taylor instability which occurs at an interface between two immiscible fluids in porous media and Hele-Shaw cells when displacing fluid is less viscous than the displaced one. The growth rate of interfacial disturbances is given by a formula called Saffman-Taylor formula which plays a very important role in many areas including flows in porous media and oil recovery among many others. In this talk, we will present our results on the generalization of this formula to multi-layer flows involving many interfaces. As an application of the generalized Saffman-Taylor formula, we will derive necessary conditions for suppressing instability of two-layer flows by introducing arbitrary number of constant viscosity fluid layers in between. The important role that these conditions play in stabilization of hydrodynamic instabilities in Hele-Shaw flows will be discussed.
Jupiter's great red spot revisited. [validity of Taylor column theory
NASA Technical Reports Server (NTRS)
Hide, R.
1972-01-01
On the original Taylor column theory of Jupiter's Great Red Spot, the fixed latitude of the Spot is taken to imply that the Taylor column in Jupiter's atmosphere is associated with a disturbance such as a topographic feature of the surface Q underlying the atmosphere. The alternative suggestion that the Taylor column is produced by a solid raft floating at depth in the atmosphere is somewhat easier to reconcile with the approximately 10s difference between the respective rotation periods P sub S and P sub R of the Red Spot and of the radio sources, but it does not account so readily for the fixed latitude of the Spot unless it can be shown that the raft is in stable equilibrium under the north-south components of the dynamical forces, including wind effects, acting upon it. A slight wavering of the upper end of the Taylor column relative to the lower end could account at least in part for the most rapid variations in P sub S, but the slow large-amplitude variations in P sub S must reflect changes in the longitudinal motion of either the surface Q or of the raft. By generalizing the Proudman-Taylor theorem to the case of a non-homogeneous fluid it is shown that the Taylor column theory does not imply very special and therefore unlikely horizontal and vertical temperature variations in Jupiter's atmosphere, thus refuting a widely-held belief to the contrary.
The Life and Legacy of G. I. Taylor
NASA Astrophysics Data System (ADS)
Batchelor, G. K.
1996-07-01
G.I. Taylor, one of the most distinguished physical scientists of this century, used his deep insight and originality to increase our understanding of phenomena such as the turbulent flow of fluids. His interest in the science of fluid flow was not confined to theory; he was one of the early pioneers of aeronautics, and designed a new type of anchor that was inspired by his passion for sailing. Taylor spent most of his working life in the Cavendish Laboratory in Cambridge, where he investigated the mechanics of fluid and solid materials; his discoveries and ideas have had application throughout mechanical, civil, and chemical engineering, meteorology, oceanography and materials science. He was also a noted research leader, and his group in Cambridge became one of the most productive centers for the study of fluid mechanics. How was Taylor able to be innovative in so many different ways? This interesting and unusual biography helps answer that question. Professor Batchelor, himself a student and close collaborator of Taylor, is ideally placed to describe Taylor's life, achievements and background. He does so without introducing any mathematical details, making this book enjoyable reading for a wide range of people--and especially those whose own interests have brought them into contact with the legacy of Taylor.
NASA Astrophysics Data System (ADS)
Taylor, M. P.; Kristensen, L. J.; Davies, P. J.; Csavina, J.; Mackay, A. K.; Munksgaard, N. C.; Hudson-Edwards, K. A.
2015-06-01
We would like to thank Dr Wilson for increasing the interest in our 2014 Aeolian Research study along with our other articles that he referred to in his letter to the journal. Before we tackle the specifics of his letter, we would like to inform the readers that our response is inclusive of several other authors whose Mount Isa research was referred to in Dr Wilson's letter.
Gender Discrimination in Jessica's Career.
ERIC Educational Resources Information Center
Cook, Ellen Piel
1997-01-01
Focuses on the sexual harassment and other gender-related difficulties faced by a Chinese-American woman. Profiles her encounters with gender discrimination and how it hindered career advancement and led to professional isolation. Relates how this case study can be used to sensitize workers to gender discrimination. (RJM)
Code of Federal Regulations, 2011 CFR
2011-07-01
... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false Taylor Creek, navigation lock (S-193) across the entrance to Taylor Creek at Lake Okeechobee, Okeechobee, Fla.; use, administration..., DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE NAVIGATION REGULATIONS § 207.170d Taylor Creek, navigation...
Code of Federal Regulations, 2010 CFR
2010-07-01
... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Taylor Creek, navigation lock (S-193) across the entrance to Taylor Creek at Lake Okeechobee, Okeechobee, Fla.; use, administration..., DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE NAVIGATION REGULATIONS § 207.170d Taylor Creek, navigation...
Taylor line swimming in microchannels and cubic lattices of obstacles.
Münch, Jan L; Alizadehrad, Davod; Babu, Sujin B; Stark, Holger
2016-09-21
Microorganisms naturally move in microstructured fluids. Using the simulation method of multi-particle collision dynamics, we study in two dimensions an undulatory Taylor line swimming in a microchannel and in a cubic lattice of obstacles, which represent simple forms of a microstructured environment. In the microchannel the Taylor line swims at an acute angle along a channel wall with a clearly enhanced swimming speed due to hydrodynamic interactions with the bounding wall. While in a dilute obstacle lattice swimming speed is also enhanced, a dense obstacle lattice gives rise to geometric swimming. This new type of swimming is characterized by a drastically increased swimming speed. Since the Taylor line has to fit into the free space of the obstacle lattice, the swimming speed is close to the phase velocity of the bending wave traveling along the Taylor line. While adjusting its swimming motion within the lattice, the Taylor line chooses a specific swimming direction, which we classify by a lattice vector. When plotting the swimming velocity versus the magnitude of the lattice vector, all our data collapse on a single master curve. Finally, we also report more complex trajectories within the obstacle lattice. PMID:27510576
Crash simulation of rayleigh-taylor, richtmyer-meshkov, and magnetic rayleigh-taylor instability
NASA Astrophysics Data System (ADS)
Chou, Jason Chuan-Chih
The research discussed in this thesis was motivated by the supernova Rayleigh-Taylor (SNRT) experiments conducted in 2009. Originally designed as laboratory astrophysics experiments relevant to the Rayleigh-Taylor Instability (RTI) at the He-H interface during supernova explosion, these experiments exhibited unusual late-time morphology development, characterized by the lack of mushroom caps and uniform width of the spikes. In response, a "Magnetic Straitjacket" hypothesis was proposed to explain the discrepancy, based on the Biermann Battery mechanism. In order to test this hypothesis, we used the Center for Radiative Shock Hydrodynamics (CRASH) code developed for a sufficiently similar problem and with the necessary capabilities. We validated this alternative usage of the CRASH code with simulations of pure hydrodynamic RTI and Richtmyer-Meshkov Instability (RMI) and identified the suitable combinations of numerical schemes and parameters. For the RTI, we compared the results of simulations to the analytical solution for the early time behavior, examined the late-time morphology, and tested the low-resolution limit for the RTI simulations using CRASH. For the RMI, we modeled Collins and Jacobs' experiment and compared the results of CRASH simulations to the experimental observations as well as to the simulation results of several other code packages. Finally, we modeled the original SNRT experiments with magnetohydrodynamics (MHD) and Biermann battery effect. Unfortunately, the results were inconclusive due to insufficiently resolved simulations, limited by the explicit time integration of the magnetic diffusion. Furthermore, pilot runs with higher resolution indicated that simulations that fully resolve the gradients necessary to calculate the Biermann battery effect may be susceptible to the development of extraneous small-wavelength instabilities. Developments of implicit time integration of the magnetic diffusion and possibly new numerical schemes are
On Using Taylor's Hypothesis for Three-Dimensional Mixing Layers
NASA Technical Reports Server (NTRS)
LeBoeuf, Richard L.; Mehta, Rabindra D.
1995-01-01
In the present study, errors in using Taylor's hypothesis to transform measurements obtained in a temporal (or phase) frame onto a spatial one were evaluated. For the first time, phase-averaged ('real') spanwise and streamwise vorticity data measured on a three-dimensional grid were compared directly to those obtained using Taylor's hypothesis. The results show that even the qualitative features of the spanwise and streamwise vorticity distributions given by the two techniques can be very different. This is particularly true in the region of the spanwise roller pairing. The phase-averaged spanwise and streamwise peak vorticity levels given by Taylor's hypothesis are typically lower (by up to 40%) compared to the real measurements.
ERIC Educational Resources Information Center
Brooks, Wanda
2009-01-01
This article analyzes the 2002 Coretta Scott King Award book by Mildred Taylor entitled "The Land". The novel and its author are situated within a tradition of historical fiction written by and about African Americans. I then offer an analysis that utilizes Critical Race Theory as an interpretive tool for examining the ways Taylor embeds meanings…
Reconnection in ICMEs by Relaxation into the Taylor State
NASA Astrophysics Data System (ADS)
Fermo, R. L.; Opher, M.; Drake, J. F.
2012-12-01
Recent in situ observations of interplanetary mass ejections (ICMEs) found signatures of reconnection exhausts in their interior or trailing edge [Gosling et al., 2007]. Whereas reconnection on the leading edge of an ICME would indicate an interaction with the coronal or interplanetary environment, this result suggests that the internal magnetic field reconnects with itself. To this end, we propose an approach borrowed from the fusion plasma community. In the context of a tokamak, Taylor [1974] showed that the lowest energy state corresponds to one in which curl B = λB. Variations from this state will result in the magnetic field trying to re-orient itself into the Taylor state solution, subject to the constraints that the toroidal flux and magnetic helicity are invariant. This relaxation is mediated by the reconnection of magnetic field lines in the m=1 mode. In tokamaks, the result is a "sawtooth crash" [Kadomtsev, 1975]. In an ICME, if we likewise treat the flux rope as a toroidal flux tube, any variation from the Taylor state will result in reconnection within the interior of the flux tube, in accord with the observation by Gosling et al. [2007]. One such way in which the Taylor state might be violated is by the elongation of the flux tube cross section in the non-radial direction, as seen in MHD simulations of flux tubes propagating through the interplanetary medium. We show analytically that this this elongation results in a violation of the Taylor state criterion curl B = λB. Lastly, we shall present PIC simulations of an elongated flux tube which has deviated from the Taylor state.
PREFACE: The 15th International Couette-Taylor Worskhop
NASA Astrophysics Data System (ADS)
Mutabazi, Innocent; Crumeyrolle, Olivier
2008-07-01
The 15th International Couette-Taylor Worskhop (ICTW15) was held in Le Havre, France from 9-12 July 2007. This regular international conference started in 1979 in Leeds, UK when the research interest in simple models of fluid flows was revitalized by systematic investigation of Rayleigh-Bénard convection and the Couette-Taylor flow. These two flow systems are good prototypes for the study of the transition to chaos and turbulence in closed flows. The workshop themes have been expanded from the original Couette-Taylor flow to include other centrifugal instabilities (Dean, Görtler, Taylor-Dean), spherical Couette flows, thermal convection instabilities, MHD, nonlinear dynamics and chaos, transition to turbulence, development of numerical and experimental techniques. The impressive longevity of the ICTW is due to the close interaction and fertile exchanges between international research groups from different disciplines: Physics and Astrophysics, Applied Mathematics, Mechanical Engineering, Chemical Engineering. The present workshop was attended by 100 participants, the program included over 83 contributions with 4 plenary lectures, 68 oral communications and 17 posters. The topics include, besides the classical Couette-Taylor flows, the centrifugal flows with longitudinal vortices, the shear flows, the thermal convection in curved geometries, the spherical Couette-Taylor flow, the geophysical flows, the magneto-hydrodynamic effects including the dynamo effect, the complex flows (viscoelasticity, immiscible fluids, bubbles and migration). Selected papers have been processed through the peer review system and are published in this issue of the Journal of Physics: Conference Series. The Workshop has been sponsored by Le Havre University, the Region Council of Haute-Normandie, Le Havre City Council, CNRS (ST2I, GdR-DYCOEC), and the European Space Agency through GEOFLOW program. The French Ministry of Defense (DGA), the Ministry of Foreign Affairs, the Ministry of
Narrow fingers in the Saffman-Taylor instability
NASA Astrophysics Data System (ADS)
Couder, Y.; Gerard, N.; Rabaud, M.
1986-12-01
Saffman-Taylor fingers with a relative width much smaller than the classical limit lambda = 0.5 are found when a small isolated bubble is located at their tip. These solutions are members of a family found by Saffman and Taylor (1958) neglecting superficial tension. Recent theories have shown that when capillary forces are taken into account an unphysical cusplike singularity would appear at the tip of all the fingers with lambda less than 0.5. Conversely, here the replacement of the tip by a small bubble makes these solutions possible. At large velocity these fingers show dendritic instability.
Controlled formation of multiple Taylor cones in electrospinning process
NASA Astrophysics Data System (ADS)
Vaseashta, A.
2007-02-01
Electrospinning is a versatile technique for preparation of micro- and nanoscale fibers using polymer solutions. The study presented here describes an observation of multiple Taylor cones in electrospinning processes. Plausible physical models explaining the formation and modeling of multiple Taylor cones in terms of the process and polymer solution parameters are presented. A thorough understanding of the process will lead to the preparation of fibers by design, system on fibers, and e-textiles having applications ranging from biomedical devices, environmental pollution and prevention, to global security and defense.
Rapid Calculation of Spacecraft Trajectories Using Efficient Taylor Series Integration
NASA Technical Reports Server (NTRS)
Scott, James R.; Martini, Michael C.
2011-01-01
A variable-order, variable-step Taylor series integration algorithm was implemented in NASA Glenn's SNAP (Spacecraft N-body Analysis Program) code. SNAP is a high-fidelity trajectory propagation program that can propagate the trajectory of a spacecraft about virtually any body in the solar system. The Taylor series algorithm's very high order accuracy and excellent stability properties lead to large reductions in computer time relative to the code's existing 8th order Runge-Kutta scheme. Head-to-head comparison on near-Earth, lunar, Mars, and Europa missions showed that Taylor series integration is 15.8 times faster than Runge- Kutta on average, and is more accurate. These speedups were obtained for calculations involving central body, other body, thrust, and drag forces. Similar speedups have been obtained for calculations that include J2 spherical harmonic for central body gravitation. The algorithm includes a step size selection method that directly calculates the step size and never requires a repeat step. High-order Taylor series integration algorithms have been shown to provide major reductions in computer time over conventional integration methods in numerous scientific applications. The objective here was to directly implement Taylor series integration in an existing trajectory analysis code and demonstrate that large reductions in computer time (order of magnitude) could be achieved while simultaneously maintaining high accuracy. This software greatly accelerates the calculation of spacecraft trajectories. At each time level, the spacecraft position, velocity, and mass are expanded in a high-order Taylor series whose coefficients are obtained through efficient differentiation arithmetic. This makes it possible to take very large time steps at minimal cost, resulting in large savings in computer time. The Taylor series algorithm is implemented primarily through three subroutines: (1) a driver routine that automatically introduces auxiliary variables and
G.I. Taylor and the Trinity test
NASA Astrophysics Data System (ADS)
Deakin, Michael A. B.
2011-12-01
The story is often told of the calculation by G.I. Taylor of the yield of the first ever atomic bomb exploded in New Mexico in 1945. It has indeed become a staple of the classroom whenever dimensional analysis is taught. However, while it is true that Taylor succeeded in calculating this figure at a time when it was still classified, most versions of the story are quite inaccurate historically. The reality is more complex than the usual accounts have it. This article sets out to disentangle fact from fiction.
Dynamic stabilization of classical Rayleigh-Taylor instability
Piriz, A. R.; Piriz, S. A.; Tahir, N. A.
2011-09-15
Dynamic stabilization of classical Rayleigh-Taylor instability is studied by modeling the interface vibration with the simplest possible wave form, namely, a sequence of Dirac deltas. As expected, stabilization results to be impossible. However, in contradiction to previously reported results obtained with a sinusoidal driving, it is found that in general the perturbation amplitude is larger than in the classical case. Therefore, no beneficial effect can be obtained from the vertical vibration of a Rayleigh-Taylor unstable interface between two ideal fluids.
NASA Astrophysics Data System (ADS)
Oyibo, A. E.
2013-12-01
/not contaminated, scrapped and washed composite cores. Similarly, for the chemically contaminated samples we had 3 different sample designs: 0%, 5% and 10% mud contaminated composite cores. Shear test were performed on the composite cores to determine the shear bond strength and the results suggested that the detrimental impact of the contamination is higher when the cores are physically contaminated i.e. when we have mud cake present at the surface of the wellbore before a cement job is performed. Also, the results showed that shear bond strength is higher for sandstone formations as compared to shale formations. Material characterization analysis was carried out to determine the micro structural changes at the cement-formation interface. The results obtained from the SEM and micro CT images taken at the bond interface confirmed that chemical contamination caused substantial changes in the spatial distribution of minerals that impacted bond strength. Keywords: Cement-Formation bond strength, mud contamination, shale, sandstone and material characterization *Corresponding author
ERIC Educational Resources Information Center
Quay, Richard H.
A bibliography of approximately 130 materials authored, coauthored, or edited by Harold A. Taylor from 1951 to 1979 on the nature of teaching in higher education is presented. Specific topics include the following: student protests, radical reform, a world university, the United Nations University, the world as teacher, the humanities in the…
Taylorism, Tylerism, and Performance Indicators: Defending the Indefensible?
ERIC Educational Resources Information Center
Helsby, Gill; Saunders, Murray
1993-01-01
Explores the antecedents to the growing interest in the use of educational performance indicators. Discusses this issue in relation to the work of economist F. W. Taylor and evaluator Ralph Tyler. Describes a five-year project that demonstrates the promise of teacher-developed performance indicators. (CFR)
Taylor Proposes Five-Year Child-Care Program.
ERIC Educational Resources Information Center
Taylor, Glen
Senator Glen Taylor of Minnesota proposed a five-year child-care program for the purposes of encouraging employer-sponsored child care and increasing by 53,000 the number of children in low-income families who were covered. This report lists central features of the program, which include: (1) tax incentives which employers can use when they build…
Rayleigh-Taylor instability experiments in a cylindrically convergent geometry
Goodwin, B.; Weir, S.
1995-08-25
Due to the sensitivity of Rayleigh-Taylor instabilities to initial conditions and due to the difficulty of forming well controlled cylindrical or spherical fluid interfaces, Rayleigh-Taylor experiments are often performed with simple, planar interfaces. Rayleigh-Taylor instability phenomena of practical interest, however, (e.g., underwater explosions, supernova core collapses, and inertial confinement fusion capsule implosions) are typically associated with cylindrical or spherical interfaces in which convergent flow effects have an important influence on the dynamics of instability growth. Recently, Meshkov et.al. have developed a novel technique for studying Rayleigh-Taylor instability growth in a cylindrically convergent geometry. Their experiments utilized low-strength gelatin rings which are imploded by a detonating gas mixture of oxygen and acetylene. Since the gelatin itself has sufficient strength to resist significant deformation by gravity, no membranes are needed to define the ring shape. This experimental technique is attractive because it offers a high degree of control over the interfacial geometry and over the material`s strength and rigidity, which can be varied by adjusting the gelatin concentration. Finally, since both the gelatin and the explosive product gases are transparent, optical diagnostics can be used.
Frank Bursley Taylor - Forgotten Pioneer of Continental Drift.
ERIC Educational Resources Information Center
Black, George W., Jr.
1979-01-01
Frank B. Taylor was an American geologist who specialized in the glacial geology of the Great Lakes. This article discusses his work on the Continental Drift theory, which preceeded the work of Alfred Wegener by a year and a half. (MA)
Evaluation of five fracture models in Taylor impact fracture
NASA Astrophysics Data System (ADS)
Zhang, Wei; Xiao, Xin-Ke; Wei, Gang; Guo, Zitao
2012-03-01
Taylor impact test presented in a previous study on a commercial high strength and super hard aluminum alloy 7A04-T6 are numerically evaluated using the finite element code ABAQUS/Explicit. In the present study, the influence of fracture criterion in numerical simulations of the deformation and fracture behavior of Taylor rod has been studied. Included in the paper are a modified version of Johnson-Cook, the Cockcroft-Latham(C-L), the constant fracture strain, the maximum shear stress and the maximum principle stress fracture models. Model constants for each criterion are calibrated from material tests. The modified version of Johnson-Cook fracture criterion with the stress triaxiality cut off idea is found to give good prediction of the Taylor impact fracture behavior. However, this study will also show that the C-L fracture criterion where only one simple material test is required for calibration is found to give reasonable predictions. Unfortunately, the other three criteria are not able to repeat the experimentally obtained fracture behavior. The study indicates that the stress triaxiality cut off idea is necessary to predict the Taylor impact fracture.
Evaluation of Five Fracture Models in Taylor Impact Fracture
NASA Astrophysics Data System (ADS)
Zhang, Wei; Xiao, Xinke; Wei, Gang; Guo, Zitao
2011-06-01
Taylor impact test presented in a previous study on a commercial high strength and super hard aluminum alloy 7A04-T6 are numerically evaluated using the finite element code ABAQUS/Explicit. In the present study, the influence of fracture criterion in numerical simulations of the deformation and fracture behavior of Taylor rod has been studied. Included in the paper are a modified version of Johnson-Cook, the Cockcroft-Latham(C-L), the constant fracture strain, the maximum shear stress and the maximum principle stress fracture models. Model constants for each criterion are calibrated from material tests. The modified version of Johnson-Cook fracture criterion with the stress triaxiality cut off idea is found to give good prediction of the Taylor impact fracture behavior. However, this study will also show that the C-L fracture criterion where only one simple material test is required for calibration, is found to give reasonable predictions. Unfortunately, the other three criteria are not able to repeat the experimentally obtained fracture behavior. The study indicates that the stress triaxiality cut off idea is necessary to predict the Taylor impact fracture. The National Natural Science Foundation of China (No.: 11072072).
Using Taylor Expansions to Prepare Students for Calculus
ERIC Educational Resources Information Center
Lutzer, Carl V.
2011-01-01
We propose an alternative to the standard introduction to the derivative. Instead of using limits of difference quotients, students develop Taylor expansions of polynomials. This alternative allows students to develop many of the central ideas about the derivative at an intuitive level, using only skills and concepts from precalculus, and…
14. INTERIOR VIEW WITH JOHNNY TAYLOR REMOVING A MOLD HALF ...
14. INTERIOR VIEW WITH JOHNNY TAYLOR REMOVING A MOLD HALF FROM THE PATTERN ON THE MOLDING MACHINE, REVEALING THE CAVITY THAT WILL BE FILLED WITH MOLTEN IRON AFTER IT IS ASSEMBLED WITH THE OTHER MOLD HALF INSIDE GREY IRON UNIT NO. 1. - Stockham Pipe & Fittings Company, Grey Iron Foundry, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL
Slavnov-Taylor identities for noncommutative QED{sub 4}
Charneski, B.; Gomes, M.; Silva, A. J. da; Mariz, T.; Nascimento, J. R.
2010-05-15
In this work we present an analysis of the one-loop Slavnov-Taylor identities in noncommutative QED{sub 4}. The vectorial fermion-photon and the triple photon vertex functions were studied, with the conclusion that no anomalies arise.
76 FR 18378 - Amendment of Class E Airspace; Taylor, AZ
Federal Register 2010, 2011, 2012, 2013, 2014
2011-04-04
... amend controlled airspace at Taylor, AZ (76 FR 3570). Interested parties were invited to participate in... Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of... U.S.C. 106(g), 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec....
Pentagon After Action Reports: The Jack Taylor Debate.
ERIC Educational Resources Information Center
Abbott, Stan
In requesting after action reports--Pentagon-prepared summaries of interviews between reporters and Pentagon officials--investigative reporter Jack Taylor both aroused Pentagon opposition and created a rift between the Pentagon press corps and outside reporters. To investigate whether the full-time Pentagon press corps was reporting as…
Taylor's Theorem and Derivative Tests for Extrema and Inflection Points
ERIC Educational Resources Information Center
Gordon, Sheldon P.
2005-01-01
The standard derivative tests for extrema and inflection points from Calculus I can be revisited subsequently from the perspective of Taylor polynomial approximations to provide additional insights into those tests, as well as to extend them to additional criteria. (Contains 3 figures.)
Rayleigh Taylor instability of viscoelastic drops at high Weber numbers
NASA Astrophysics Data System (ADS)
Joseph, D. D.; Beavers, G. S.; Funada, T.
2002-02-01
Movies of the breakup of viscous and viscoelastic drops in the high-speed airstream behind a shock wave in a shock tube have been reported by Joseph, Belanger & Beavers (1999). They performed a Rayleigh Taylor stability analysis for the initial breakup of a drop of Newtonian liquid and found that the most unstable Rayleigh Taylor wave fits nearly perfectly with waves measured on enhanced images of drops from the movies, but the effects of viscosity cannot be neglected. Here we construct a Rayleigh Taylor stability analysis for an Oldroyd-B fluid using measured data for acceleration, density, viscosity and relaxation time [lambda]1. The most unstable wave is a sensitive function of the retardation time [lambda]2 which fits experiments when [lambda]2/[lambda]1 = O(10-3). The growth rates for the most unstable wave are much larger than for the comparable viscous drop, which agrees with the surprising fact that the breakup times for viscoelastic drops are shorter. We construct an approximate analysis of Rayleigh Taylor instability based on viscoelastic potential flow which gives rise to nearly the same dispersion relation as the unapproximated analysis.
13. INTERIOR VIEW WITH JOHNNY TAYLOR HAND LEVELING FRESHLY DEPOSITED ...
13. INTERIOR VIEW WITH JOHNNY TAYLOR HAND LEVELING FRESHLY DEPOSITED SAND INTO A FLASK PRIOR TO COMPRESSION BY THE MOLDING MACHINE INSIDE GREY IRON UNIT NO. 1. - Stockham Pipe & Fittings Company, Grey Iron Foundry, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL
Detached eddy simulations of Taylor bubbles rising in stagnant liquid columns
NASA Astrophysics Data System (ADS)
Shaban, Hassan; Tavoularis, Stavros
2015-11-01
The rise of a single air Taylor bubble in a vertical circular tube filled with stagnant water was investigated numerically using the Volume Of Fluid (VOF) method to model the phase distribution and the Detached Eddy Simulation (DES) method for turbulence modelling. The predictions were in good quantitative agreement with previous experimental results. The simulation results provided insight into bubble shedding in the wake of the Taylor bubble, frictional pressure drop along the tube and scalar dispersion caused by the passage of the Taylor bubble. The interaction between adjacent Taylor bubbles and the process of Taylor bubble coalescence were also examined in detail. Supported by NSERC and UNENE.
Kilkenny, J.D.
1994-08-04
As shown elsewhere an ablatively imploded shell is hydrodynamically unstable, the dominant instability being the well known Rayleigh-Taylor instability with growth rate {gamma} = {radical}Akg where k = 2{pi}/{lambda} is the wave number, g is the acceleration and A the Attwood number ({rho}{sub hi} {minus} {rho}{sub lo})/({rho}{sub hi} + {rho}{sub lo}) where {rho}{sub hi} is the density of the heavier fluid and {rho}{sub lo} is the density of the lighter fluid. A theoretical understanding of ablative stabilization has gradually evolved, confirmed over the last five years by experiments. The linear growth is very well understood with excellent agreement between experiment and simulation for planar geometry with wavelengths in the region of 30--100{mu}m. There is an accurate, albeit phenomenological dispersion relation. The non-linear growth has been measured and agrees with calculations. In this lecture, the authors go into the fundamentals of the Rayleigh-Taylor instability and the experimental measurements that show it is stabilized sufficiently by ablation in regimes relevant to ICF.
Perry, F.V. ); Baldridge, W.S. ); DePaolo, D.J. Lawrence Berkeley Lab., Berkeley, CA ); Shafiqullah, M. )
1990-11-10
In this paper the authors present geologic mapping, K-Ar chronology, major and trace element data, mineral chemistry, and Nd, Sr, and O isotopic data for volcanic rocks of the Mount Taylor volcanic field (MTVF). The MTVF lies on the tectonic boundary between the Basin and Range province and the southeastern Colorado Plateau and is dominated by Mount Taylor, a composite volcano active from {approx}3 to 1.5 m.y. ago. Growth of the volcano began with eruption of rhyolite, followed by quartz latite and finally latite. Basalts erupted throughout the lifetime of the volcano. Rare mixing of evolved hy-hawaiite and rhyolite produced a few intermediate magmas, primarily in the early history of the field. Mixing may have occurred when rhyolite magmas in the lower crust ascended to upper crustal levels and were injected into the bases of mafic magma chambers. Small amounts of crustal assimilation accompanied fractional crystallization and affected all the evolved MTVF rocks. Assimilation/fractional crystallization occurred primarily in the lower crust as hy-hawaiite differentiated to mugearite or latite. Early in the history of the field, evolved lower crustal magmas ascended into the upper crust, where density filtering and a reduced tensional stress field inhibited further ascent until magmas evolved to rhyolite or quartz latite. Later in the history of the field, latite magmas ascended directly from the lower crust and erupted without further significant differentiation because of increased crustal extension.
Press, Carol M
2005-01-01
Psychoanalysis and creativity are not interchangeable enterprises; however, both creativity and psychoanalysis promise the hope of transformation. But hope may be fragile. Healthy aspects of self may hide and diminish hope to protect it against invasion from toxic pathological patterns. Hope may be rekindled by an empathically responsive environment and the reengagement of healthy forward edge strivings. Psychoanalysis illustrates creativity as a conduit for hope. Modern dance choreographer Paul Taylor's 1988 autobiography, Private Domain, describes Taylor's hope and strivings through creative engagement. Unfortunately, when Taylor's body inevitably falters after years of performing, he is unprepared psychologically to cope successfully. Taylor's sense of self begins to fragment and his forward edge strivings to decay. Eventually, Taylor collapses on stage from drug addiction and illness; his performing career crashes to an end. Taylor must search for his forward edge strivings with hope. Psychoanalysis illuminates Taylor's journey to find hope, motivation, meaningful intention, and transformation through creativity and dance-making. PMID:15953780
Stability of the Taylor--Culick receding rim: surprising observations
NASA Astrophysics Data System (ADS)
Lhuissier, Henri; Villermaux, Emmanuel
2008-11-01
When punctured, a uniform liquid sheet is known, since Taylor and Culick, to recess at a constant speed balancing surface tension and inertia. For planar soap films, this steady solution holds until the initially smooth receding rim is violently destabilized, exhibiting deep indentations from which droplets are ejected. A surprising new three dimensional mechanism explaining this destabilization and resulting wavelength has been evidenced : because of the shear between the still outer medium and the receding liquid, the film flaps through a Kelvin--Helmholtz instability, itself inducing an acceleration perpendicular to the film, which intensifies with the flapping amplitude. To this acceleration is associated a classical Rayleigh--Taylor mechanism, promoting the rim indentations. The same mechanism holds for a punctured round bubble, for which the relevant acceleration is the Culick velocity squared divided by the bubble radius. The bearing of this phenomenon on aerosols formation in Nature will be underlined.
Measurements of small radius ratio turbulent Taylor-Couette flow
NASA Astrophysics Data System (ADS)
van der Veen, Roeland; Huisman, Sander; Merbold, Sebastian; Sun, Chao; Harlander, Uwe; Egbers, Christoph; Lohse, Detlef
2014-11-01
In Taylor-Couette flows, the radius ratio (η =ri /ro) is one of the key parameters of the system. For small η, the asymmetry of the inner and outer boundary layer becomes more important, affecting the general flow structure and boundary layer characteristics. Using high-resolution particle image velocimetry we measure flow profiles, local transport, and statistical properties of the flow for a radius ratio of 0.5 and a Reynolds number of up to 4 .104 . By measuring flow profiles at varying heights, roll structures are characterized for two different rotation ratios of the inner and outer cylinder. In addition, we systematically vary the rotation ratio and the Reynolds number. These results exemplify how curvature affects flow in strongly turbulent Taylor-Couette Flow.
Multiple states in highly turbulent Taylor-Couette flow
NASA Astrophysics Data System (ADS)
Huisman, Sander G.; van der Veen, Roeland C. A.; Sun, Chao; Lohse, Detlef
2014-05-01
The ubiquity of turbulent flows in nature and technology makes it of utmost importance to fundamentally understand turbulence. Kolmogorov’s 1941 paradigm suggests that for strongly turbulent flows with many degrees of freedom and large fluctuations, there would only be one turbulent state as the large fluctuations would explore the entire higher dimensional phase space. Here we report the first conclusive evidence of multiple turbulent states for large Reynolds number, Re(106) (Taylor number Ta(1012)) Taylor-Couette flow in the regime of ultimate turbulence, by probing the phase space spanned by the rotation rates of the inner and outer cylinder. The manifestation of multiple turbulent states is exemplified by providing combined global torque- and local-velocity measurements. This result verifies the notion that bifurcations can occur in high-dimensional flows (that is, very large Re) and questions Kolmogorov’s paradigm.
Multiple states in highly turbulent Taylor-Couette flow
NASA Astrophysics Data System (ADS)
Huisman, Sander; van der Veen, Roeland; Sun, Chao; Lohse, Detlef
2014-11-01
The ubiquity of turbulent flows in nature and technology makes it of utmost importance to fundamentally understand turbulence. Kolmogorov's 1941 paradigm suggests that for strongly turbulent flows with many degrees of freedom and its large fluctuations, there would only be one turbulent state as the large fluctuations would explore the entire higher-dimensional phase space. Here we report the first conclusive evidence of multiple turbulent states for large Reynolds number Re = O (106) (Taylor number Ta = O (1012) Taylor-Couette flow in the regime of ultimate turbulence, by probing the phase space spanned by the rotation rates of the inner and outer cylinder. The manifestation of multiple turbulent states is exemplified by providing combined global torque and local velocity measurements. This result verifies the notion that bifurcations can occur in high-dimensional flows (i.e. very large Re) and questions Kolmogorov's paradigm.
A Taylor weak-statement algorithm for hyperbolic conservation laws
NASA Technical Reports Server (NTRS)
Baker, A. J.; Kim, J. W.
1987-01-01
Finite element analysis, applied to computational fluid dynamics (CFD) problem classes, presents a formal procedure for establishing the ingredients of a discrete approximation numerical solution algorithm. A classical Galerkin weak-statement formulation, formed on a Taylor series extension of the conservation law system, is developed herein that embeds a set of parameters eligible for constraint according to specification of suitable norms. The derived family of Taylor weak statements is shown to contain, as special cases, over one dozen independently derived CFD algorithms published over the past several decades for the high speed flow problem class. A theoretical analysis is completed that facilitates direct qualitative comparisons. Numerical results for definitive linear and nonlinear test problems permit direct quantitative performance comparisons.
Singularities in water waves and Rayleigh-Taylor instability
NASA Technical Reports Server (NTRS)
Tanveer, S.
1991-01-01
Singularities in inviscid two-dimensional finite-amplitude water waves and inviscid Rayleigh-Taylor instability are discussed. For the deep water gravity waves of permanent form, through a combination of analytical and numerical methods, results describing the precise form, number, and location of singularities in the unphysical domain as the wave height is increased are presented. It is shown how the information on the singularity in the unphysical region has the same form as for deep water waves. However, associated with such a singularity is a series of image singularities at increasing distances from the physical plane with possibly different behavior. Furthermore, for the Rayleigh-Taylor problem of motion of fluid over a vacuum and for the unsteady water wave problem, integro-differential equations valid in the unphysical region are derived, and how these equations can give information on the nature of singularities for arbitrary initial conditions is shown.
Structures in Transitional Taylor-Couette Flows Identified using POD
NASA Astrophysics Data System (ADS)
Balabani, Stavroula; Imomoh, Eboshogwe; Dusting, Jonathan
2009-11-01
The flow in the gap between concentric cylinders, or Taylor-Couette flow, has been used to study transition to turbulence for decades, and is also utilised for various biotechnological and industrial processes. Transitional flow states depend highly on vessel geometry; they are also three-dimensional and often time dependent limiting the use of experimental techniques for their characterisation. In this talk the transition to turbulence in a Taylor-Couette flow is studied by means of time resolved PIV velocity fields and Proper Orthogonal Decomposition (POD). It is found that for the particular geometry studied the transition to turbulence occurs via a quasi periodic regime characterised by a fast moving azimuthal wave (FMAW). Aspects of the FMAW structure, such as a series of co-rotating vortices that increase in strength away from the endwalls, are also revealed by spatially resolved POD.
Rayleigh-Taylor vortices in a pair-ion plasma
Adak, Ashish Khan, Manoranjan
2015-04-15
The Rayleigh-Taylor (RT) vortices and the analytical solution of three-mode coupling in pair-ion plasmas are investigated. It is shown that the E×B convection of polarization drift is responsible for the saturation of growing RT instability and as a result the localized dipole vortex structures are formed. The shear flow generation due to the destruction of vortex structures is discussed by the Fourier mode analysis.
Nonlinear Rayleigh-Taylor instability of rotating inviscid fluids
NASA Astrophysics Data System (ADS)
Tao, J. J.; He, X. T.; Ye, W. H.; Busse, F. H.
2013-01-01
It is demonstrated theoretically that the nonlinear stage of the Rayleigh-Taylor instability can be retarded at arbitrary Atwood numbers in a rotating system with the axis of rotation normal to the acceleration of the interface between two uniform inviscid fluids. The Coriolis force provides an effective restoring force on the perturbed interface, and the uniform rotation will always decrease the nonlinear saturation amplitude of the interface at any disturbance wavelength.
Rayleigh-Taylor instability in dusty plasma experiment
Avinash, K.; Sen, A.
2015-08-15
The stability of a stratified dust cloud levitated in an anodic plasma is studied in the weakly and strongly coupled dust regimes. It is shown that the cloud is predominantly unstable to a Rayleigh-Taylor (RT) instability driven by a component of the ambient gravity in a direction opposite to the direction of dust density stratification in the cloud. The elasticity of the strongly coupled dust is shown to set a threshold for the RT instability, which is consistent with experimental observations.
Glacier geophysical studies at Taylor Dome: Your three
Morse, D.L.; Waddington, E.D. )
1993-01-01
Taylor Dome is the site of an ongoing ice core/paleoclimate project. The main activities of the 1992-1993 season included surveys by ground-based optical methods, surveys using satellite receivers, radio-echo sounding of bedrock topography, and depositional environment characterization. Monitoring continued of accumulation rate and three cores were sampled to detect the depths of atmospheric nuclear test fallout products. 5 refs., 1 fig.
Viscous Rayleigh-Taylor instability in spherical geometry
Mikaelian, Karnig O.
2016-02-08
We consider viscous fluids in spherical geometry, a lighter fluid supporting a heavier one. Chandrasekhar [Q. J. Mech. Appl. Math. 8, 1 (1955)] analyzed this unstable configuration providing the equations needed to find, numerically, the exact growth rates for the ensuing Rayleigh-Taylor instability. He also derived an analytic but approximate solution. We point out a weakness in his approximate dispersion relation (DR) and offer one that is to some extent improved.
General theory of Taylor dispersion phenomena. Part 3. Surface transport
Dill, L.H.; Brenner, H.
1982-01-01
An asymptotic theory of Brownian tracer particle transport phenomena within a bulk fluid, as augmented by surface transport, is presented in the context of generalized Taylor dispersion theory. The analysis expands upon prior work, which was limited to transport wholly within a continuous phase, so as to now include surface adsorption, diffusion, and convection of the tracer along a continuous surface bounding the continuous fluid phase.
Numerical study of a Taylor bubble rising in stagnant liquids.
Kang, Chang-Wei; Quan, Shaoping; Lou, Jing
2010-06-01
The dynamics of a Taylor bubble rising in stagnant liquids is numerically investigated using a front tracking coupled with finite difference method. Parametric studies on the dynamics of the rising Taylor bubble including the final shape, the Reynolds number (Re(T)), the Weber number (We(T)), the Froude number (Fr), the thin liquid film thickness (w/D), and the wake length (l(w)/D) are carried out. The effects of density ratio (η), viscosity ratio (λ), Eötvös number (Eo), and Archimedes number (Ar) are examined. The simulations demonstrate that the density ratio and the viscosity ratio under consideration have minimal effect on the dynamics of the Taylor bubble. Eötvös number and Archimedes number influence the elongation of the tail and the wake structures, where higher Eo and Ar result in longer wake. To explain the sudden extension of the tail, a Weber number (We(l)) based on local curvature and velocity is evaluated and a critical We(l) is detected around unity. The onset of flow separation at the wake occurs in between Ar=2×10(3) and Ar=1×10(4), which corresponds to Re(T) between 13.39 and 32.55. Archimedes number also drastically affects the final shape of Taylor bubble, the terminal velocity, the thickness of thin liquid film, as well as the wall shear stress. It is found that w/D=0.32 Ar(-0.1). PMID:20866523
Rayleigh-Taylor instability in an equal mass plasma
Adak, Ashish; Ghosh, Samiran; Chakrabarti, Nikhil
2014-09-15
The Rayleigh-Taylor (RT) instability in an inhomogeneous pair-ion plasma has been analyzed. Considering two fluid model for two species of ions (positive and negative), we obtain the possibility of the existence of RT instability. The growth rate of the RT instability as usual depends on gravity and density gradient scale length. The results are discussed in context of pair-ion plasma experiments.
Displacement Maps in Taylor Impact Using Speckle Radiography
NASA Astrophysics Data System (ADS)
Grantham, S. G.; Braithwaite, C. H.; Proud, W. G.; Williamson, D. M.
2006-07-01
A method was developed at the Cavendish Laboratory (Cambridge University) to determine the internal displacement characteristics of a polymer rod undergoing classic Taylor impact. Using a layer of lead filings on the central plane of the rod and Digital Speckle Radiography with flash x-rays it was possible to build up a dynamic displacement map. This technique can be used to derive material properties such as yield strength and provide data for model validation.
Taylor's Theorem: The Elusive "c" Is Not So Elusive
ERIC Educational Resources Information Center
Kreminski, Richard
2010-01-01
For a suitably nice, real-valued function "f" defined on an open interval containing [a,b], f(b) can be expressed as p[subscript n](b) (the nth Taylor polynomial of f centered at a) plus an error term of the (Lagrange) form f[superscript (n+1)](c)(b-a)[superscript (n+1)]/(n+1)! for some c in (a,b). This article is for those who think that not…
Solving ODE Initial Value Problems With Implicit Taylor Series Methods
NASA Technical Reports Server (NTRS)
Scott, James R.
2000-01-01
In this paper we introduce a new class of numerical methods for integrating ODE initial value problems. Specifically, we propose an extension of the Taylor series method which significantly improves its accuracy and stability while also increasing its range of applicability. To advance the solution from t (sub n) to t (sub n+1), we expand a series about the intermediate point t (sub n+mu):=t (sub n) + mu h, where h is the stepsize and mu is an arbitrary parameter called an expansion coefficient. We show that, in general, a Taylor series of degree k has exactly k expansion coefficients which raise its order of accuracy. The accuracy is raised by one order if k is odd, and by two orders if k is even. In addition, if k is three or greater, local extrapolation can be used to raise the accuracy two additional orders. We also examine stability for the problem y'= lambda y, Re (lambda) less than 0, and identify several A-stable schemes. Numerical results are presented for both fixed and variable stepsizes. It is shown that implicit Taylor series methods provide an effective integration tool for most problems, including stiff systems and ODE's with a singular point.
Numerical study of Taylor bubbles with adaptive unstructured meshes
NASA Astrophysics Data System (ADS)
Xie, Zhihua; Pavlidis, Dimitrios; Percival, James; Pain, Chris; Matar, Omar; Hasan, Abbas; Azzopardi, Barry
2014-11-01
The Taylor bubble is a single long bubble which nearly fills the entire cross section of a liquid-filled circular tube. This type of bubble flow regime often occurs in gas-liquid slug flows in many industrial applications, including oil-and-gas production, chemical and nuclear reactors, and heat exchangers. The objective of this study is to investigate the fluid dynamics of Taylor bubbles rising in a vertical pipe filled with oils of extremely high viscosity (mimicking the ``heavy oils'' found in the oil-and-gas industry). A modelling and simulation framework is presented here which can modify and adapt anisotropic unstructured meshes to better represent the underlying physics of bubble rise and reduce the computational effort without sacrificing accuracy. The numerical framework consists of a mixed control-volume and finite-element formulation, a ``volume of fluid''-type method for the interface capturing based on a compressive control volume advection method, and a force-balanced algorithm for the surface tension implementation. Numerical examples of some benchmark tests and the dynamics of Taylor bubbles are presented to show the capability of this method. EPSRC Programme Grant, MEMPHIS, EP/K0039761/1.
Taylor bubbles at high viscosity ratios: experiments and numerical simulations
NASA Astrophysics Data System (ADS)
Hewakandamby, Buddhika; Hasan, Abbas; Azzopardi, Barry; Xie, Zhihua; Pain, Chris; Matar, Omar
2015-11-01
The Taylor bubble is a single long bubble which nearly fills the entire cross section of a liquid-filled circular tube, often occurring in gas-liquid slug flows in many industrial applications, particularly oil and gas production. The objective of this study is to investigate the fluid dynamics of three-dimensional Taylor bubble rising in highly viscous silicone oil in a vertical pipe. An adaptive unstructured mesh modelling framework is adopted here which can modify and adapt anisotropic unstructured meshes to better represent the underlying physics of bubble rising and reduce computational effort without sacrificing accuracy. The numerical framework consists of a mixed control volume and finite element formulation, a `volume of fluid'-type method for the interface-capturing based on a compressive control volume advection method, and a force-balanced algorithm for the surface tension implementation. Experimental results for the Taylor bubble shape and rise velocity are presented, together with numerical results for the dynamics of the bubbles. A comparison of the simulation predictions with experimental data available in the literature is also presented to demonstrate the capabilities of our numerical method. EPSRC Programme Grant, MEMPHIS, EP/K0039761/1.
Taylor Impact Tests and Simulations on PBX 9501
NASA Astrophysics Data System (ADS)
Clements, Brad; Thompson, Darla G.; Luscher, D. J.; Deluca, Racci
2011-06-01
Taylor impact tests have been conducted previously on plastic bonded explosives (PBXs) to characterize the stress state of these materials as they impact smooth and flat steel anvil surfaces at speeds of ~100m/s (i.e. Christopher, et al, 11th Detonation Symposium). In 2003, C. Liu and R. Ellis (unpublished, Los Alamos National Laboratory) performed Taylor tests on PBX 9501 up to speeds of 115 m/s, capturing impact images. In the work presented here, we have extended these tests to velocities of 200 m/s using a composite-lined gun barrel and no specimen sabot. Specimen images are used to validate the thermo-mechanical constitutive model ViscoSCRAM. ViscoSCRAM has been parameterized for PBX 9501 in uniaxial stress configurations. Simulating Taylor impact experiments tests the model in situations undergoing extreme damage. In addition, experimental variations to specimen confinement and friction are introduced in an attempt to establish ignition thresholds in this velocity regime.
Parameterizing the power spectrum: Beyond the truncated Taylor expansion
Abazajian, Kevork; Kadota, Kenji; Stewart, Ewan D.; /KAIST, Taejon /Canadian Inst. Theor. Astrophys.
2005-07-01
The power spectrum is traditionally parameterized by a truncated Taylor series: ln P(k) = ln P{sub *} + (n{sub *} - 1) ln(k/k{sub *}) + 1/2 n'{sub *} ln{sup 2} (k/k{sub *}). It is reasonable to truncate the Taylor series if |n'{sub *} ln(k/k{sub *})| << |n{sub *} - 1|, but it is not if |n'{sub *} ln(k/k{sub *})| {approx}> |n{sub *} - 1|. We argue that there is no good theoretical reason to prefer |n'{sub *}| << |n{sub *} - 1|, and show that current observations are consistent with |n*{sub *} ln(k/k{sub *})| {approx} |n{sub *} - 1| even for |ln(k/k{sub *})| {approx} 1. Thus, there are regions of parameter space, which are both theoretically and observationally relevant, for which the traditional truncated Taylor series parameterization is inconsistent, and hence it can lead to incorrect parameter estimations. Motivated by this, we propose a simple extension of the traditional parameterization, which uses no extra parameters, but that, unlike the traditional approach, covers well motivated inflationary spectra with |n'{sub *}| {approx} |n{sub *} - 1|. Our parameterization therefore covers not only standard-slow-roll inflation models but also a much wider class of inflation models. We use this parameterization to perform a likelihood analysis for the cosmological parameters.
Aerial EM Survey Reveals Groundwater Systems Beneath Taylor Valley, Antarctica
NASA Astrophysics Data System (ADS)
Dugan, H.; Mikucki, J.; Auken, E.; Tulaczyk, S. M.; Virginia, R. A.; Schamper, C.; Sørensen, K.; Doran, P. T.; Foley, N.
2014-12-01
The extent of groundwater and its potential habitability in the ice-free regions and along the coastal margins of Antarctica is poorly understood. Here we report on an airborne transient electromagnetic survey in Antarctica, which for the first time produced extensive imagery of subsurface resistivity in Taylor Valley, an ice-free margin of the Ross Sea. Wide zones of low subsurface resistivity were detected that are inconsistent with the typical high resistivity of glacier ice or dry permafrost. These results are interpreted as an indication that water, with sufficiently high solute content to remain unfrozen well below 0°C, temperatures considered within the range suitable for microbial life. The inferred subsurface brines are widespread and form two isolated groundwater systems: a near shore system, which extends from the ocean 18 km inland; and a sub-/proglacial system, which emanates from beneath Taylor Glacier into Lake Bonney and is associated with the discharge from Blood Falls. The brine networks in Taylor Valley challenge the notion that groundwater is negligible in regions of continuous permafrost, and signify the potential for a deep biosphere that is hydrologically and geochemically connected to the marine system and subglacial environments.
Fluctuations in Saffman-Taylor fingers with quenched disorder
NASA Astrophysics Data System (ADS)
Torralba, M.; Ortín, J.; Hernández-Machado, A.; Corvera Poiré, E.
2006-04-01
We make an experimental characterization of the effect that static disorder has on the shape of a normal Saffman-Taylor finger. We find that static noise induces a small amplitude and long wavelength instability on the sides of the finger. Fluctuations on the finger sides have a dominant wavelength, indicating that the system acts as a selective amplifier of static noise. The dominant wavelength does not seem to be very sensitive to the intensity of static noise present in the system. On the other hand, at a given flow rate, rms fluctuations of the finger width, decrease with decreasing intensity of static noise. This might explain why the sides of the fingers are flat for typical Saffman-Taylor experiments. Comparison with previous numerical studies of the effect that temporal noise has on the Saffman-Taylor finger, leads to conclude that the effect of temporal noise and static noise are similar. The behavior of fluctuations of the finger width found in our experiments, is qualitatively similar to one recently reported, in the sense that, the magnitude of the width fluctuations decays as a power law of the capillary number, at low flow rates, and increases with capillary number for larger flow rates.
The effect of crossflow on Taylor vortices: A model problem
NASA Technical Reports Server (NTRS)
Otto, S. R.; Bassom, Andrew P.
1993-01-01
A number of practically relevant problems involving the impulsive motion or the rapid rotation of bodies immersed in fluid are susceptible to vortex-like instability modes. Depending upon the configuration of any particular problem the stability properties of any high-wavenumber vortices can take on one of two distinct forms. One of these is akin to the structure of Gortler vortices in boundary layer flows while the other is similar to the situation for classical Taylor vortices. Both the Gortler and Taylor problems have been extensively studied when crossflow effects are excluded from the underlying base flows. Recently, studies were made concerning the influence of crossflow on Gortler modes and a linearized stability analysis is used to examine crossflow properties for the Taylor mode. This work allows us to identify the most unstable vortex as the crossflow component increases and it is shown how, like the Gortler case, only a very small crossflow component is required in order to completely stabilize the flow. Our investigation forms the basis for an extension to the nonlinear problem and is of potential applicability to a range of pertinent flows.
High-Reynolds Number Taylor-Couette Turbulence
NASA Astrophysics Data System (ADS)
Grossmann, Siegfried; Lohse, Detlef; Sun, Chao
2016-01-01
Taylor-Couette flow, the flow between two coaxial co- or counter-rotating cylinders, is one of the paradigmatic systems in the physics of fluids. The (dimensionless) control parameters are the Reynolds numbers of the inner and outer cylinders, the ratio of the cylinder radii, and the aspect ratio. One key response of the system is the torque required to retain constant angular velocities, which can be connected to the angular velocity transport through the gap. Whereas the low-Reynolds number regime was well explored in the 1980s and 1990s of the past century, in the fully turbulent regime major research activity developed only in the past decade. In this article, we review this recent progress in our understanding of fully developed Taylor-Couette turbulence from the experimental, numerical, and theoretical points of view. We focus on the parameter dependence of the global torque and on the local flow organization, including velocity profiles and boundary layers. Next, we discuss transitions between different (turbulent) flow states. We also elaborate on the relevance of this system for astrophysical disks (quasi-Keplerian flows). The review ends with a list of challenges for future research on turbulent Taylor-Couette flow.
Dynamic response of reverse Taylor impact based on DIC technology
NASA Astrophysics Data System (ADS)
Liu, Jiancheng; Pi, Aiguo; Wu, Haijun; Huang, Fenglei
2015-09-01
Reverse ballistic impact test, which can obtain the response data of rod/projectile more comprehensive and quantitative than forward impact test, was widely used for the measurement of material dynamic and structure response. Based on the DIC technology and traditional optical measurement (high-speed camera measurement), the Taylor experiment of reverse ballistic with different length-diameter ratio and different impact velocities were carried out by 57 mm compression-shear type light-gas gun, which provides the instantaneous response data of the Taylor rod in microsecond level. Then, the transient structural deformation of the specimen and the characteristics of plastic wave propagation were analysed by DIC technology and compared with traditional optical measurement. Applying the theory of reverse Taylor impact deformation and combining with the simulation results by LS-DYNA, the rules of structure deformation and plastic wave propagation were obtained. The method above can be applied for the structure response of penetrator under the condition of reverse ballistic penetration.
Taylor impact tests on PBX composites: imaging and analysis
NASA Astrophysics Data System (ADS)
Graff Thompson, Daria; DeLuca, Racci; Archuleta, Jose; Brown, Geoff W.; Koby, Joseph
2014-05-01
A series of Taylor impact tests were performed on three plastic bonded explosive (PBX) formulations: PBX 9501, PBXN-9 and HPP (propellant). The first two formulations are HMX-based, and all three have been characterized quasi-statically in tension and compression. The Taylor impact tests use a 500 psi gas gun to launch PBX projectiles (approximately 30 grams, 16 mm diameter, 76 mm long), velocities as high as 215 m/s, at a steel anvil. Tests were performed remotely and no sign of ignition/reaction have been observed to date. Highspeed imaging was used to capture the impact of the specimen onto anvil surface. Side-view contour images have been analyzed using dynamic stress equations from the literature, and additionally, front-view images have been used to estimate a tensile strain failure criterion for initial specimen fracture. Post-test sieve analysis of specimen debris correlates fragmentation with projectile velocity, and these data show interesting differences between composites. Along with other quasi-static and dynamic measurements, Taylor impact images and fragmentation data provide a useful metric for the calibration or evaluation of intermediate-rate model predictions of PBX constituitive response and failure/fragmentation. Intermediate-rate tests involving other impact configurations are being considered.
NASA Astrophysics Data System (ADS)
Treviranus, Jutta
Authoring tools that are accessible and that enable authors to produce accessible Web content play a critical role in web accessibility. Widespread use of authoring tools that comply to the W3C Authoring Tool Accessibility Guidelines (ATAG) would ensure that even authors who are neither knowledgeable about nor particularly motivated to produce accessible content do so by default. The principles and techniques of ATAG are discussed. Some examples of accessible authoring tools are described including authoring tool content management components such as TinyMCE. Considerations for creating an accessible collaborative environment are also covered. As part of providing accessible content, the debate between system-based personal optimization and one universally accessible site configuration is presented. The issues and potential solutions to address the accessibility crisis presented by the advent of rich internet applications are outlined. This challenge must be met to ensure that a large segment of the population is able to participate in the move toward the web as a two-way communication mechanism.
ERIC Educational Resources Information Center
Martz, Carlton; Hayes, Bill
2001-01-01
This issue of "Bill of Rights in Action" explores questions of military authority. The first article looks at the French Army mutinies in World War I and how the French Army dealt with them. The second article examines President Truman's firing of popular and powerful General Douglas MacArthur during the Korean War. The final article looks at how…
Phase mixed rotation magnetoconvection and Taylor's condition III. Wave trains
NASA Astrophysics Data System (ADS)
Ewen, Susan A.; Soward, Andrew M.
Nonlinear amplitude equations governing the radial modulation of quasi-geostrophic convective rolls, which occur in a rapidly rotating self-gravitating sphere permeated by a weak azimuthal magnetic field (small Elsasser number), were derived in Part I. Stationary and travelling pulse solutions were obtained in Part II. That analysis is extended here; wave train solutions are sought and their stability tested. Special features of the equations include: nonlinear diffusion and dispersion; also phase mixing, which leads to a lack of translational invariance of the system. In spite of the latter, the underlying structure of the wave trains sought is spatially periodic on a length L, but modulated by a time dependent Floquet exponent. Consequently, a Fourier representation is employed and the time evolution of the Fourier coefficients is determined numerically. It is shown that pulses confined to lengths l(< L) can be superimposed non-interactively to form wave trains. The numerical demonstration relies on establishing that the pseudo-energy based on the time averaged wave train amplitude coincides with the corresponding pulse energy E calculated in Part II. When l and L are comparable some pulse interaction can be inferred. Available numerical evidence suggests that wave trains, and by implication pulses, are unstable. The geophysical implications are discussed. All finite amplitude solutions pertain to the Ekman regime in which the modified Taylor's condition is satisfied by small magnetic field perturbations. Only in the infinite amplitude limit do the solutions determine true Taylor states. It is anticipated that following instability in the Ekman regime convection equilibrates in some large amplitude Taylor state, which is determined when additional ageostrophic effects are taken into account. Analysis of that state lies outside the range of validity of our amplitude equations.
Optimal Taylor-Couette flow: radius ratio dependence
NASA Astrophysics Data System (ADS)
Ostilla-Mónico, Rodolfo; Huisman, Sander G.; Jannink, Tim J. G.; Van Gils, Dennis P. M.; Verzicco, Roberto; Grossmann, Siegfried; Sun, Chao; Lohse, Detlef
2014-05-01
Taylor-Couette flow with independently rotating inner (i) and outer (o) cylinders is explored numerically and experimentally to determine the effects of the radius ratio {\\eta} on the system response. Numerical simulations reach Reynolds numbers of up to Re_i=9.5 x 10^3 and Re_o=5x10^3, corresponding to Taylor numbers of up to Ta=10^8 for four different radius ratios {\\eta}=r_i/r_o between 0.5 and 0.909. The experiments, performed in the Twente Turbulent Taylor-Couette (T^3C) setup, reach Reynolds numbers of up to Re_i=2x10^6$ and Re_o=1.5x10^6, corresponding to Ta=5x10^{12} for {\\eta}=0.714-0.909. Effective scaling laws for the torque J^{\\omega}(Ta) are found, which for sufficiently large driving Ta are independent of the radius ratio {\\eta}. As previously reported for {\\eta}=0.714, optimum transport at a non-zero Rossby number Ro=r_i|{\\omega}_i-{\\omega}_o|/[2(r_o-r_i){\\omega}_o] is found in both experiments and numerics. Ro_opt is found to depend on the radius ratio and the driving of the system. At a driving in the range between {Ta\\sim3\\cdot10^8} and {Ta\\sim10^{10}}, Ro_opt saturates to an asymptotic {\\eta}-dependent value. Theoretical predictions for the asymptotic value of Ro_{opt} are compared to the experimental results, and found to differ notably. Furthermore, the local angular velocity profiles from experiments and numerics are compared, and a link between a flat bulk profile and optimum transport for all radius ratios is reported.
Rayleigh-Taylor instability with finite current relaxation
NASA Astrophysics Data System (ADS)
Silveira, F. E. M.; Orlandi, H. I.
2016-04-01
In this work, we explore the influence of perturbative wavelengths, shorter than those usually considered, on the growth rate of the Rayleigh-Taylor modes. Therefore, we adopt an extended form of Ohm's law which includes a finite relaxation time of the current density due to inertial effects of charged species in the plasma. The restoring force density that acts upon charged species close to the mode rational surface takes into account a new term which is usually neglected with respect to the motional electromotive force. We find that the width of the resistive layer can be interpreted in terms of the "height" of free fall in a constant gravitational field, in the Alfvén time interval. We also show that the charged species must fall "down" in the constant gravitational field in order that the static state of equilibrium of the system becomes unstable to the linear perturbation. Through the principle of conservation of energy, we find a general formula which gives the growth rate γ of the Rayleigh-Taylor modes. When the new term becomes negligible with respect to the motional electromotive force, we recover the standard result of the Rayleigh-Taylor instability, which establishes that γ scales with the plasma resistivity η as γ ˜ η 1 / 3 . However, in the opposite limiting situation, we find that γ does not depend any longer on the plasma resistivity and scales now with the electron number density n e as γ ˜ ne - 1 / 2 . Further developments of our theory may contribute to improve our understanding on the excitation mechanisms of resistive plasma instabilities by transient phenomena such as shock waves.
On Taylor-Series Approximations of Residual Stress
NASA Technical Reports Server (NTRS)
Pruett, C. David
1999-01-01
Although subgrid-scale models of similarity type are insufficiently dissipative for practical applications to large-eddy simulation, in recently published a priori analyses, they perform remarkably well in the sense of correlating highly against exact residual stresses. Here, Taylor-series expansions of residual stress are exploited to explain the observed behavior and "success" of similarity models. Until very recently, little attention has been given to issues related to the convergence of such expansions. Here, we re-express the convergence criterion of Vasilyev [J. Comput. Phys., 146 (1998)] in terms of the transfer function and the wavenumber cutoff of the grid filter.
Bubble Counts for Rayleigh-Taylor Instability Using Image Analysis
Miller, P L; Gezahegne, A G; Cook, A W; Cabot, W H; Kamath, C
2007-01-24
We describe the use of image analysis to count bubbles in 3-D, large-scale, LES [1] and DNS [2] of the Rayleigh-Taylor instability. We analyze these massive datasets by first converting the 3-D data to 2-D, then counting the bubbles in the 2-D data. Our plots for the bubble count indicate there are four distinct regimes in the process of the mixing of the two fluids. We also show that our results are relatively insensitive to the choice of parameters in our analysis algorithms.
Rayleigh-Taylor instability in quantum magnetized viscous plasma
Hoshoudy, G. A.
2011-09-15
Quantum effects on Rayleigh-Taylor instability of stratified viscous plasmas layer under the influence of vertical magnetic field are investigated. By linearly solving the viscous QMHD equations into normal mode, a forth-order ordinary differential equation is obtained to describe the velocity perturbation. Then the growth rate is derived for the case where a plasma with exponential density distribution is confined between two rigid planes. The results show that, the presence of vertical magnetic field beside the quantum effect will bring about more stability on the growth rate of unstable configuration for viscous plasma, which is greater than that of inviscous plasma.
THE RAYLEIGH-TAYLOR INSTABILITY IN SMALL ASPECT RATIO CONTAINERS
RIVERA, MICHAEL K.; ECKE, ROBERT E.
2007-01-22
We present experimental measurements of density and velocity obtained from the mixing zone of buoyancy driven turbulence initiated by the Rayleigh-Taylor instability in a small aspect ration chamber (a chamber who's vertical height is significantly larger than its lateral dimesion). The mixing front propogates at a slightly slower rate than the expected t{sup 2} behavior obtained from earlier experiments and numerics. Once the front has propogated significantly far away, we observe that the mixing zone develops to a statistically stationary state. In this stationary state, the spectral distributions of energy and density deviate from the familiar k{sup -5/3} ubiquitous to turbulence in three dimensions.
Nonlinear magnetoconvection in a rapidly rotating sphere and Taylor's constraint
NASA Astrophysics Data System (ADS)
Fearn, D. R.; Proctor, M. R. E.; Sellar, C. C.
We investigate thermally driven convection in a rapidly rotating sphere in the presence of a prescribed azimuthal magnetic field B1. Earlier work has looked at the linear problem. Here, we include the most important nonlinear effect; the geostrophic flow VG(s)1. This is determined through the standard condition that leads to Taylor's (1963) constraint in the limit of vanishing viscosity. The present work therefore follows on from earlier work on both kinematic α- and αω-dynamos and magnetoconvection. Examples of the latter have so far been restricted to plane-layer, duct and cylindrical geometries. The present work uses a spherical geometry and makes a further step towards physical realism in that the contributions from both the axisymmetric and non-axisymmetric components of the magnetic field to the Taylor integral are included. (The earlier magnetoconvection work only included the non-axisymmetric contributions while the kinematic dynamo calculations involved only the axisymmetric contributions). The problem is solved by integrating the governing partial differential equations forward in time. Ekman states [where the amplitude of the non-axisymmetric convection is controlled by the Ekman boundary layer and is O(E¼), where E is the Ekman number] are found for values of the modified Rayleigh number ? both above and (in at least one example) slightly below the critical value ? c (in the absence of any differential rotation). The latter behaviour implies that the convective instability can be subcritical and this can be understood on the basis of the linear result that, for small amplitudes, a differential rotation can act to decrease ? c. (The reasons for this and the conditions under which this happens are not yet well understood, but are currently under investigation.) Two further main features have emerged from our calculations: the non-axisymmetric contribution to the Taylor integral typically dominates the axisymmetric contribution, and a complicated time
Photographic copy of architectural drawings for Building 4315: Taylor & ...
Photographic copy of architectural drawings for Building 4315: Taylor & Barnes, Architects & Engineers, 803 W. Third Street, Los Angeles California, O.C.E. Office of Civil Engineer Job No. Muroc ESA 210-50 and 210-44, Military Construction: Muroc Flight Test Base, Muroc, California, Utility Yard & Shops: Carpenter & Paint Shop, Utility Shop & Lavatory, Plan & Elevations, Sheet No. 4 of 8, May 1945. Reproduced from the holdings of the National Archives, Pacific Southwest Region - Edwards Air Force Base, North Base, Utility & Paint Shop, Second & E Streets, Boron, Kern County, CA
2. Photographic copy of architectural elevations for Building 4505, Taylor ...
2. Photographic copy of architectural elevations for Building 4505, Taylor & Barnes, Architects & Engineers, 803 W. Third Street, Los Angeles California, O.C.E. Office of Civil Engineer Job No. A(9-10), Military Construction: Materiel Command Flight Test Base, Muroc, California, Hangar and Auxiliary Buildings: Hangar Type P-A, Exterior Elevations, Sheet No. 18, March 1944. Reproduced from the holdings of the National Archives, Pacific Southwest Region - Edwards Air Force Base, North Base, Hangar, End of North Base Road, Boron, Kern County, CA
1. Photographic copy of architectural plan for Building 4505, Taylor ...
1. Photographic copy of architectural plan for Building 4505, Taylor & Barnes, Architects & Engineers, 803 W. Third Street, Los Angeles California, O.C.E. Office of Civil Engineer Job No. A(9-10), Military Construction: Materiel Command Flight Test Base, Muroc, California, Hangar and Auxiliary Buildings: Hangar Type P-A, Floor Plan & Roof Plan, Sheet No. 16, March 1944. Reproduced from the holdings of the National Archives, Pacific Southwest Region - Edwards Air Force Base, North Base, Hangar, End of North Base Road, Boron, Kern County, CA
Theoretical and Experimental Studies of Magneto-Rayleigh-Taylor Instabilities
Lau, Yue Ying; Gilgenbach, Ronald
2013-07-07
Magneto-Rayleigh-Taylor instability (MRT) is important to magnetized target fusion, wire-array z-pinches, and equation-of-state studies using flyer plates or isentropic compression. It is also important to the study of the crab nebula. The investigators performed MRT experiments on thin foils, driven by the mega-ampere linear transformer driver (LTD) facility completed in their laboratory. This is the first 1-MA LTD in the USA. Initial experiments on the seeding of MRT were performed. Also completed was an analytic study of MRT for a finite plasma slab with arbitrary magnetic fields tangential to the interfaces. The effects of magnetic shear and feedthrough were analyzed.
Simulating Hamiltonian dynamics with a truncated Taylor series.
Berry, Dominic W; Childs, Andrew M; Cleve, Richard; Kothari, Robin; Somma, Rolando D
2015-03-01
We describe a simple, efficient method for simulating Hamiltonian dynamics on a quantum computer by approximating the truncated Taylor series of the evolution operator. Our method can simulate the time evolution of a wide variety of physical systems. As in another recent algorithm, the cost of our method depends only logarithmically on the inverse of the desired precision, which is optimal. However, we simplify the algorithm and its analysis by using a method for implementing linear combinations of unitary operations together with a robust form of oblivious amplitude amplification. PMID:25793789
Taylor's experiment in a periodically sheared particulate suspension
NASA Astrophysics Data System (ADS)
Souzy, Mathieu; Pham, Phong; Metzger, Bloen
2016-08-01
We revisit Taylor's experiment investigating the evolution of a blob of dye in a periodically sheared suspension of non-Brownian particles. Above a critical strain amplitude, particulate suspensions are subject to phase transition where reversibility is lost and particles fail to return to their original positions. We investigate the effect of this transition on the dispersion of a blob of dye. Beyond the critical strain, the dispersion of the blob is found to increase significantly. The dispersion coefficient of the blob of dye is measured and compared to the self-diffusivity coefficient of the particles.
High Speed Solution of Spacecraft Trajectory Problems Using Taylor Series Integration
NASA Technical Reports Server (NTRS)
Scott, James R.; Martini, Michael C.
2008-01-01
Taylor series integration is implemented in a spacecraft trajectory analysis code-the Spacecraft N-body Analysis Program (SNAP) - and compared with the code s existing eighth-order Runge-Kutta Fehlberg time integration scheme. Nine trajectory problems, including near Earth, lunar, Mars and Europa missions, are analyzed. Head-to-head comparison at five different error tolerances shows that, on average, Taylor series is faster than Runge-Kutta Fehlberg by a factor of 15.8. Results further show that Taylor series has superior convergence properties. Taylor series integration proves that it can provide rapid, highly accurate solutions to spacecraft trajectory problems.
NASA Technical Reports Server (NTRS)
1999-01-01
Author of Rocket Boys Homer Hickam, Jr. (left) and Marshall Space Flight Center Director Art Stephenson during a conference at Morris Auditorium. Homer Hickam worked at MSFC during the Apollo project years. As a young man, Mr. Hickam always dreamed of becoming a rocket scientist and following in the footsteps fo Wernher von Braun. Years later he would see his dream realized and had written Rocket Boys commemorating his life and the people at MSFC.
Rayleigh-Taylor instability of viscous fluids with phase change
NASA Astrophysics Data System (ADS)
Kim, Byoung Jae; Kim, Kyung Doo
2016-04-01
Film boiling on a horizontal surface is a typical example of the Rayleigh-Taylor instability. During the film boiling, phase changes take place at the interface, and thus heat and mass transfer must be taken into consideration in the stability analysis. Moreover, since the vapor layer is not quite thick, a viscous flow must be analyzed. Existing studies assumed equal kinematic viscosities of two fluids, and/or considered thin viscous fluids. The purpose of this study is to derive the analytical dispersion relation of the Rayleigh-Taylor instability for more general conditions. The two fluids have different properties. The thickness of the vapor layer is finite, but the liquid layer is thick enough to be nearly semi-infinite in view of perturbation. Initially, the vapor is in equilibrium with the liquid at the interface, and the direction of heat transfer is from the vapor side to the liquid side. In this case, the phase change has a stabilizing effect on the growth rate of the interface. When the vapor layer is thin, there is a coupled effect of the vapor viscosity, phase change, and vapor thickness on the critical wave number. For the other limit of a thick vapor, both the liquid and vapor viscosities influence the critical wave number. Finally, the most unstable wavelength is investigated. When the vapor layer is thin, the most unstable wavelength is not affected by phase change. When the vapor layer is thick, however, it increases with the increasing rate of phase change.
Transition to turbulence in Taylor-Couette ferrofluidic flow
Altmeyer, Sebastian; Do, Younghae; Lai, Ying-Cheng
2015-01-01
It is known that in classical fluids turbulence typically occurs at high Reynolds numbers. But can turbulence occur at low Reynolds numbers? Here we investigate the transition to turbulence in the classic Taylor-Couette system in which the rotating fluids are manufactured ferrofluids with magnetized nanoparticles embedded in liquid carriers. We find that, in the presence of a magnetic field transverse to the symmetry axis of the system, turbulence can occur at Reynolds numbers that are at least one order of magnitude smaller than those in conventional fluids. This is established by extensive computational ferrohydrodynamics through a detailed investigation of transitions in the flow structure, and characterization of behaviors of physical quantities such as the energy, the wave number, and the angular momentum through the bifurcations. A finding is that, as the magnetic field is increased, onset of turbulence can be determined accurately and reliably. Our results imply that experimental investigation of turbulence may be feasible by using ferrofluids. Our study of transition to and evolution of turbulence in the Taylor-Couette ferrofluidic flow system provides insights into the challenging problem of turbulence control. PMID:26065572
Transition to turbulence in Taylor-Couette ferrofluidic flow.
Altmeyer, Sebastian; Do, Younghae; Lai, Ying-Cheng
2015-01-01
It is known that in classical fluids turbulence typically occurs at high Reynolds numbers. But can turbulence occur at low Reynolds numbers? Here we investigate the transition to turbulence in the classic Taylor-Couette system in which the rotating fluids are manufactured ferrofluids with magnetized nanoparticles embedded in liquid carriers. We find that, in the presence of a magnetic field transverse to the symmetry axis of the system, turbulence can occur at Reynolds numbers that are at least one order of magnitude smaller than those in conventional fluids. This is established by extensive computational ferrohydrodynamics through a detailed investigation of transitions in the flow structure, and characterization of behaviors of physical quantities such as the energy, the wave number, and the angular momentum through the bifurcations. A finding is that, as the magnetic field is increased, onset of turbulence can be determined accurately and reliably. Our results imply that experimental investigation of turbulence may be feasible by using ferrofluids. Our study of transition to and evolution of turbulence in the Taylor-Couette ferrofluidic flow system provides insights into the challenging problem of turbulence control. PMID:26065572
Simulating Hamiltonian Dynamics with a Truncated Taylor Series
NASA Astrophysics Data System (ADS)
Somma, Rolando
2015-03-01
One of the main motivations for quantum computers is their ability to efficiently simulate the dynamics of quantum systems. Since the mid-1990s, many algorithms have been developed to simulate Hamiltonian dynamics on a quantum computer, with applications to problems such as simulating spin models and quantum chemistry. While it is now well known that quantum computers can efficiently simulate Hamiltonian dynamics, ongoing work has improved the performance and expanded the scope of such simulations. In this talk, I will describe a very simple and efficient algorithm for simulating Hamiltonian dynamics on a quantum computer by approximating the truncated Taylor series of the evolution operator. This algorithm can simulate the time evolution of a wide variety of physical systems. The cost of this algorithm depends only logarithmically on the inverse of the desired precision, and can be shown to be optimal. Such a cost also represents an exponential improvement over known methods for Hamiltonian simulation based on, e.g., Trotter-Suzuki approximations. Roughly speaking, doubling the number of digits of accuracy of the simulation only doubles the complexity. The new algorithm and its analysis are highly simplified due to a technique for implementing linear combinations of unitary operations to directly apply the truncated Taylor series. This is joint work with Dominic Berry, Andrew Childs, Richard Cleve, and Robin Kothari.
Rayleigh-Taylor instability of viscous fluids with phase change.
Kim, Byoung Jae; Kim, Kyung Doo
2016-04-01
Film boiling on a horizontal surface is a typical example of the Rayleigh-Taylor instability. During the film boiling, phase changes take place at the interface, and thus heat and mass transfer must be taken into consideration in the stability analysis. Moreover, since the vapor layer is not quite thick, a viscous flow must be analyzed. Existing studies assumed equal kinematic viscosities of two fluids, and/or considered thin viscous fluids. The purpose of this study is to derive the analytical dispersion relation of the Rayleigh-Taylor instability for more general conditions. The two fluids have different properties. The thickness of the vapor layer is finite, but the liquid layer is thick enough to be nearly semi-infinite in view of perturbation. Initially, the vapor is in equilibrium with the liquid at the interface, and the direction of heat transfer is from the vapor side to the liquid side. In this case, the phase change has a stabilizing effect on the growth rate of the interface. When the vapor layer is thin, there is a coupled effect of the vapor viscosity, phase change, and vapor thickness on the critical wave number. For the other limit of a thick vapor, both the liquid and vapor viscosities influence the critical wave number. Finally, the most unstable wavelength is investigated. When the vapor layer is thin, the most unstable wavelength is not affected by phase change. When the vapor layer is thick, however, it increases with the increasing rate of phase change. PMID:27176406
On spatial pattern of concentration distribution for Taylor dispersion process
NASA Astrophysics Data System (ADS)
Wu, Zi; Fu, Xudong; Wang, Guangqian
2016-02-01
Taylor dispersion is a key concept in many fields. In the present paper, we characterize the pattern of the complete spatial concentration distribution for laminar tube flow; the obtained simple description is shown to represent the nature of Taylor dispersion. Importantly, we find that during the approach to the longitudinal normality of the transverse mean concentration at the time scale of R2/D (R is the tube radius and D is the molecular diffusivity), the solute concentration becomes uniformly distributed across a family of invariant curved transverse surfaces instead of the flat cross-sections in the traditional view. The family of curved surfaces is analytically determined, and a transformation is devised for the previously obtained analytical solution to discuss the decay of the concentration difference across the curved surfaces. The approach to a uniform concentration across the flat cross-sections to the same degree (~3% by concentration difference percentage), achieved at a time-scale of 100 R2/D, is shown to be the natural consequence of the longitudinal separation of the concentration contours on the curved surfaces.
Rayleigh-Taylor mixing with time-dependent acceleration
NASA Astrophysics Data System (ADS)
Abarzhi, Snezhana
2015-11-01
We extend the momentum model to describe Rayleigh-Taylor (RT) mixing driven by a time-dependent acceleration. The acceleration is a power-law function of time, similarly to astrophysical and plasma fusion applications. In RT flow the dynamics of a fluid parcel is driven by a balance per unit mass of the rates of momentum gain and loss. We find analytical solutions in the cases of balanced and imbalanced gains and losses, and identify their dependence on the acceleration exponent. The existence is shown of two typical regimes of self-similar RT mixing -acceleration-driven Rayleigh-Taylor-type and dissipation-driven Richtymer-Meshkov-type with the latter being in general non-universal. Possible scenarios are proposed for transitions from the balanced dynamics to the imbalanced self-similar dynamics. Scaling and correlations properties of RT mixing are studied on the basis of dimensional analysis. Departures are outlined of RT dynamics with time-dependent acceleration from canonical cases of homogeneous turbulence as well as blast waves with first and second kind self-similarity. Support of National Science Foundation is warmy appreciated.
On spatial pattern of concentration distribution for Taylor dispersion process.
Wu, Zi; Fu, Xudong; Wang, Guangqian
2016-01-01
Taylor dispersion is a key concept in many fields. In the present paper, we characterize the pattern of the complete spatial concentration distribution for laminar tube flow; the obtained simple description is shown to represent the nature of Taylor dispersion. Importantly, we find that during the approach to the longitudinal normality of the transverse mean concentration at the time scale of R(2)/D (R is the tube radius and D is the molecular diffusivity), the solute concentration becomes uniformly distributed across a family of invariant curved transverse surfaces instead of the flat cross-sections in the traditional view. The family of curved surfaces is analytically determined, and a transformation is devised for the previously obtained analytical solution to discuss the decay of the concentration difference across the curved surfaces. The approach to a uniform concentration across the flat cross-sections to the same degree (~3% by concentration difference percentage), achieved at a time-scale of 100 R(2)/D, is shown to be the natural consequence of the longitudinal separation of the concentration contours on the curved surfaces. PMID:26867803
The Inhibition of the Rayleigh-Taylor Instability by Rotation
Baldwin, Kyle A.; Scase, Matthew M.; Hill, Richard J. A.
2015-01-01
It is well-established that the Coriolis force that acts on fluid in a rotating system can act to stabilise otherwise unstable flows. Chandrasekhar considered theoretically the effect of the Coriolis force on the Rayleigh-Taylor instability, which occurs at the interface between a dense fluid lying on top of a lighter fluid under gravity, concluding that rotation alone could not stabilise this system indefinitely. Recent numerical work suggests that rotation may, nevertheless, slow the growth of the instability. Experimental verification of these results using standard techniques is problematic, owing to the practical difficulty in establishing the initial conditions. Here, we present a new experimental technique for studying the Rayleigh-Taylor instability under rotation that side-steps the problems encountered with standard techniques by using a strong magnetic field to destabilize an otherwise stable system. We find that rotation about an axis normal to the interface acts to retard the growth rate of the instability and stabilise long wavelength modes; the scale of the observed structures decreases with increasing rotation rate, asymptoting to a minimum wavelength controlled by viscosity. We present a critical rotation rate, dependent on Atwood number and the aspect ratio of the system, for stabilising the most unstable mode. PMID:26130005
The Inhibition of the Rayleigh-Taylor Instability by Rotation.
Baldwin, Kyle A; Scase, Matthew M; Hill, Richard J A
2015-01-01
It is well-established that the Coriolis force that acts on fluid in a rotating system can act to stabilise otherwise unstable flows. Chandrasekhar considered theoretically the effect of the Coriolis force on the Rayleigh-Taylor instability, which occurs at the interface between a dense fluid lying on top of a lighter fluid under gravity, concluding that rotation alone could not stabilise this system indefinitely. Recent numerical work suggests that rotation may, nevertheless, slow the growth of the instability. Experimental verification of these results using standard techniques is problematic, owing to the practical difficulty in establishing the initial conditions. Here, we present a new experimental technique for studying the Rayleigh-Taylor instability under rotation that side-steps the problems encountered with standard techniques by using a strong magnetic field to destabilize an otherwise stable system. We find that rotation about an axis normal to the interface acts to retard the growth rate of the instability and stabilise long wavelength modes; the scale of the observed structures decreases with increasing rotation rate, asymptoting to a minimum wavelength controlled by viscosity. We present a critical rotation rate, dependent on Atwood number and the aspect ratio of the system, for stabilising the most unstable mode. PMID:26130005
Nonlinear effects for the Taylor column for a hemisphere
NASA Technical Reports Server (NTRS)
Crisalli, A. J.; Walker, J. D. A.
1976-01-01
When a flow is forced past an obstacle in a rapidly rotating fluid, a Taylor column forms. This is defined by a set of vertical detached shear layers circumscribing the obstacle which provide the smooth transition from an external inviscid potential flow to a stagnant core above the obstacle. For a hemispherical object, the main adjustment takes place in an external E to the 1/4 power layer and an internal E to the 2/7 power layer; here, the nonlinear flow in these layers is investigated. The problem in the E to the 1/4 power layer is identical to a problem occurring in magnetohydrodynamic flow; in addition, some features of the magnetohydrodynamic problem have been resolved. Numerical solutions are obtained for the steady nonlinear external E to the 1/4 power layer flow up to the point where unsteady flow separation from the Taylor column is imminent. The response of the internal E to the 2/7 power layer to the flow in the E to the 1/4 power layer is calculated, and the results suggest that the internal shear layer is unlikely to play any significant role in the separation process
Instability vaccination: A structural design to reduce Rayleigh Taylor instability
NASA Astrophysics Data System (ADS)
Esmaeili, Amin
2013-10-01
Instability vaccination can be defined as designing a structure to stimulate the system in order to develop immunity against its instability. In this work we have tried to do this stabilization by a new technique. Previously some suppression of R-M instability was done by insertion of magnetic field, but in this work we have tried to do this suppression by proposing a configuration similar to the shape of instability, we call it instability vaccination. This design will reduce the rotations (mostly rotations of Rayleigh Taylor instability) in the fluids that cause more mixing and instabilities. In this paper, we consider the evolution of the interface between two ideal semi-infinite fluid surfaces, using two-dimensional Riemann solver, to solve the Euler equations. First, we performed evolution of a rectangular disorder between the 2 surfaces using two-dimensional Riemann problem for the equations of Euler. Next, the interface was replaced with a perturbation that was part rectangular and part semi-circular (like a mushroom). The simulation was continued till some time steps using the HLL method. We have seen that the rotations of Rayleigh Taylor (R-T) instability were decreased in the second case. Email: amin@cavelab.cs.tsukuba.ac.jp
A novel control strategy for a Taylor-Couette flow
NASA Astrophysics Data System (ADS)
Bouabdallah, A.; Oualli, H.; Mekadem, M.; Boukrif, M.; Saad, S.; Gad-El-Hak, M.
2015-11-01
Advancing transition is desired in applications where heat, mass, or momentum transfer needs to be augmented. On the other hand, delaying transition is imperative in crystal growth devices, where all instabilities are to be avoided in order to prevent the appearance of geometrical irregularities in the resulting crystal. The hydrodynamic stability of a viscous flow in a closed, fully filled Taylor-Couette system is considered in the present numerical study. The fluid evolves in an annular cavity between the rotating inner cylinder and the outer fixed one. The base flow is axis-symmetric with two counter-rotating vortices each wavelength. The Taylor number varies in the range of 0-50. Numerical simulations are implemented on a finite-volume CFD code. The control strategy involves a pulsatile motion superimposed separately on the inner and outer cylinder's cross-section, with maximum amplitude of, respectively, 5% and 15% of the radius. The frequency varies in the range of 0-100 Hz. The objective is to localize the transition and to assess the flow's response to the imposed boundary motions. Substantial advancement of transition is found when the inner cylinder's cross-section is varied, while this transition is delayed when the outer cylinder's cross-section is pulsating.
Taylor Impact Tests on PBX Composites: Imaging and Analysis
NASA Astrophysics Data System (ADS)
Thompson, Darla; Deluca, Racci
2013-06-01
A series of Taylor impact tests were performed on three plastic bonded explosive (PBX) formulations: PBX 9501, PBXN-9 and HPP (propellant). The first two formulations are HMX-based, and all three have been characterized quasi-statically in tension and compression. The Taylor impact tests use a 500 psi gas gun to launch PBX projectiles (approximately 30 grams, 16 mm diameter, 76 mm long) at velocities as high as 215 m/s. Tests were performed remotely and no sign of ignition/reaction have been observed to date. High-speed imaging was used to capture the impact of the specimen onto the surface of a steel anvil. Side-view contour images have been analyzed using dynamic stress equations from the literature, and additionally, front-view images have been used to estimate a tensile strain failure criterion for initial specimen fracture. Post-test sieve analysis of specimen debris correlates fragmentation with projectile velocity, and these data show interesting differences between composites. Along with other quasi-static and dynamic measurements, these impact images and fragmentation data provide a useful metric for the calibration or evaluation of intermediate-rate model predictions of PBX constituitive response and failure/fragmentation. Intermediate-rate tests involving other impact configurations are being considered.
Klosek, K.
1996-12-31
The results of the authors several years of model research using analog ground medium of Taylor-Schneebeli type to the multiparametric simulations of mining area deformations are presented in the paper. On the basis of the model similarity criteria the complete usefulness was proven of this research approach to the analysis of process of joint action of the mining rock mass and ground structures, underground infrastructures, engineering structures and road surface, also with use of geosynthetics.
43 CFR 4170.2-1 - Penal provisions under the Taylor Grazing Act.
Code of Federal Regulations, 2012 CFR
2012-10-01
... 43 Public Lands: Interior 2 2012-10-01 2012-10-01 false Penal provisions under the Taylor Grazing...-EXCLUSIVE OF ALASKA Penalties § 4170.2-1 Penal provisions under the Taylor Grazing Act. Under section 2 of the Act any person who willfully commits an act prohibited under § 4140.1(b), or who...
43 CFR 4170.2-1 - Penal provisions under the Taylor Grazing Act.
Code of Federal Regulations, 2013 CFR
2013-10-01
... 43 Public Lands: Interior 2 2013-10-01 2013-10-01 false Penal provisions under the Taylor Grazing...-EXCLUSIVE OF ALASKA Penalties § 4170.2-1 Penal provisions under the Taylor Grazing Act. Under section 2 of the Act any person who willfully commits an act prohibited under § 4140.1(b), or who...
43 CFR 4170.2-1 - Penal provisions under the Taylor Grazing Act.
Code of Federal Regulations, 2014 CFR
2014-10-01
... 43 Public Lands: Interior 2 2014-10-01 2014-10-01 false Penal provisions under the Taylor Grazing...-EXCLUSIVE OF ALASKA Penalties § 4170.2-1 Penal provisions under the Taylor Grazing Act. Under section 2 of the Act any person who willfully commits an act prohibited under § 4140.1(b), or who...
Taylor-Made Education: The Influence of the Efficiency Movement on the Testing of Reading Skills.
ERIC Educational Resources Information Center
Allen, JoBeth
Much of what has developed in the testing of reading harkens back to the days of the "Cult of Efficiency" movement in education that can be largely attributed to Frederick Winslow Taylor. Taylor spent most of his productive years studying time and motion in an attempt to streamline industrial production so that people could work as quickly and…
43 CFR 4170.2-1 - Penal provisions under the Taylor Grazing Act.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 43 Public Lands: Interior 2 2011-10-01 2011-10-01 false Penal provisions under the Taylor Grazing Act. 4170.2-1 Section 4170.2-1 Public Lands: Interior Regulations Relating to Public Lands (Continued...-EXCLUSIVE OF ALASKA Penalties § 4170.2-1 Penal provisions under the Taylor Grazing Act. Under section 2...
Preferential accumulation of bubbles in Couette-Taylor flow patterns
NASA Astrophysics Data System (ADS)
Climent, Eric; Simonnet, Marie; Magnaudet, Jacques
2007-08-01
We investigate the migration of bubbles in several flow patterns occurring within the gap between a rotating inner cylinder and a concentric fixed outer cylinder. The time-dependent evolution of the two-phase flow is predicted through three-dimensional Euler-Lagrange simulations. Lagrangian tracking of spherical bubbles is coupled with direct numerical simulation of the Navier-Stokes equations. We assume that bubbles do not influence the background flow (one-way coupling simulations). The force balance on each bubble takes into account buoyancy, added-mass, viscous drag, and shear-induced lift forces. For increasing velocities of the rotating inner cylinder, the flow in the fluid gap evolves from the purely azimuthal steady Couette flow to Taylor toroidal vortices and eventually a wavy vortex flow. The migration of bubbles is highly dependent on the balance between buoyancy and centripetal forces (mostly due to the centripetal pressure gradient) directed toward the inner cylinder and the vortex cores. Depending on the rotation rate of the inner cylinder, bubbles tend to accumulate alternatively along the inner wall, inside the core of Taylor vortices or at particular locations within the wavy vortices. A stability analysis of the fixed points associated with bubble trajectories provides a clear understanding of their migration and preferential accumulation. The location of the accumulation points is parameterized by two dimensionless parameters expressing the balance of buoyancy, centripetal attraction toward the inner rotating cylinder, and entrapment in Taylor vortices. A complete phase diagram summarizing the various regimes of bubble migration is built. Several experimental conditions considered by Djéridi, Gabillet, and Billard [Phys. Fluids 16, 128 (2004)] are reproduced; the numerical results reveal a very good agreement with the experiments. When the rotation rate is increased further, the numerical results indicate the formation of oscillating bubble
The numerical solution of ordinary differential equations by the Taylor series method
NASA Technical Reports Server (NTRS)
Silver, A. H.; Sullivan, E.
1973-01-01
A programming implementation of the Taylor series method is presented for solving ordinary differential equations. The compiler is written in PL/1, and the target language is FORTRAN IV. The reduction of a differential system to rational form is described along with the procedures required for automatic numerical integration. The Taylor method is compared with two other methods for a number of differential equations. Algorithms using the Taylor method to find the zeroes of a given differential equation and to evaluate partial derivatives are presented. An annotated listing of the PL/1 program which performs the reduction and code generation is given. Listings of the FORTRAN routines used by the Taylor series method are included along with a compilation of all the recurrence formulas used to generate the Taylor coefficients for non-rational functions.
Viscous Rayleigh-Taylor instability in spherical geometry
NASA Astrophysics Data System (ADS)
Mikaelian, Karnig O.
2016-02-01
We consider viscous fluids in spherical geometry, a lighter fluid supporting a heavier one. Chandrasekhar [Q. J. Mech. Appl. Math. 8, 1 (1955), 10.1093/qjmam/8.1.1] analyzed this unstable configuration providing the equations needed to find, numerically, the exact growth rates for the ensuing Rayleigh-Taylor instability. He also derived an analytic but approximate solution. We point out a weakness in his approximate dispersion relation (DR) and offer a somewhat improved one. A third DR, based on transforming a planar DR into a spherical one, suffers no unphysical predictions and compares reasonably well with the exact work of Chandrasekhar and a more recent numerical analysis of the problem [Terrones and Carrara, Phys. Fluids 27, 054105 (2015), 10.1063/1.4921648].
Saffman-Taylor Instability for a non-Newtonian fluid
NASA Astrophysics Data System (ADS)
Daripa, Prabir
2013-11-01
Motivated by applications, we study classical Saffman-Taylor instability involving displacement of an Oldroyd-B fluid displaced by air in a Hele-Shaw cell. The lubrication approximation is used by neglecting the vertical component of the velocity. We obtain an explicit expression of one of the components of the extra-stress perturbations tensor in terms of the horizontal velocity perturbations. The main result is an explicit formula for the growth constant (in time) of perturbations, given by a ratio in which a term depending on the relaxation and retardation (time) constants appears in the denominator of the ratio. This exact result compares extremely well with known numerical results. It is found that flow is more unstable than the corresponding Newtonian case. This is a joint work with Gelu Pasa. The research has been made possible by an NPRP Grant # 08-777-1-141 from the Qatar National Research Fund (a member of the Qatar Foundation).
A novel technique for performing symmetric Taylor impact
NASA Astrophysics Data System (ADS)
Walley, S. M.; Taylor, N. E.; Williamson, D. M.; Jardine, A. P.
2015-09-01
A novel spring tensioned wire cradle arrangement has been developed to hold the target rod lightly but firmly in place when performing rod-on-rod (symmetric Taylor) impact in a vacuum. In addition, a soft capture system has been designed and used to decelerate both rods while reducing the chance of them colliding a second time. High-speed photography was used to obtain the profile of a pure aluminium target rod as a function of time. Photon Doppler Velocimetry (PDV) was also deployed to record the velocity of the rear of the target rod as a function of time. Voiding in the interior of recovered rods was investigated non-destructively using X-ray tomography. The data provides comprehensive validation information for predictive constitutive models.
Bubble Acceleration in the Ablative Rayleigh-Taylor Instability
Betti, R.; Sanz, J.
2006-11-20
The highly nonlinear evolution of the single-mode Rayleigh-Taylor instability (RTI) at the ablation front of an accelerated target is investigated in the parameter range typical of inertial confinement fusion implosions. A new phase of the nonlinear bubble evolution is discovered. After the linear growth phase and a short constant-velocity phase, it is found that the bubble is accelerated to velocities well above the classical value. This acceleration is driven by the vorticity accumulation inside the bubble resulting from the mass ablation adn vorticity convection off the ablation front. While the albative growth rates are slower than their classical values in the linear regime, the ablative RTI grows faster than the classical RTI in the nonlinear regime for deuterium and tritium ablators.
Modified Taylor Complex Figure: normative data from 290 adults.
Casarotti, Alessandra; Papagno, Costanza; Zarino, Barbara
2014-09-01
Data for copying and delayed recall (after a 15-min delay) of the Modified Taylor Complex Figure (MTCF), an alternative form of the Rey-Osterrieth Complex Figure (ROCF), were collected from 290 healthy participants. Normative data are provided. Age and education were significantly correlated with MTCF scores and must be corrected for to interpret results accurately. More specifically, increasing age adversely affected performance, whereas a higher education resulted in a better performance. Twenty-five participants were tested with both complex figures (MTCF and ROCF) in two separate sessions to assess correlation, which proved to be high. The collected data allow using the MTCF as a valid alternative material for testing visual long-term memory avoiding implicit learning that can occur when the same version of the ROCF is used for repeated testing sessions. PMID:23647550
The cylindrical magnetic Rayleigh-Taylor instability for viscous fluids
Chambers, K.; Forbes, L. K.
2012-10-15
This paper considers a cylindrical Rayleigh-Taylor instability, in which a heavy fluid surrounds a light fluid, and gravity is directed radially inwards. A massive object is located at the centre of the light fluid, and it behaves like a line dipole both for fluid flow and magnetic field strength. The initially circular interface between the two conducting fluids evolves into plumes, dependent on the magnetic and fluid dipole strengths and the nature of the initial disturbance to the interface. A spectral method is presented to solve the time-dependent interface shapes, and results are presented and discussed. Bipolar solutions are possible, and these are of particular relevance to astrophysics. The solutions obtained resemble structures of some HII regions and nebulae.
Classical Rayleigh-Taylor instability experiments at Nova
Budil, K.S.; Remington, B.A.; Weber, S.V.; Perry, T.S.; Peyser, T.A.
1997-11-10
The evolution of the Rayleigh-Taylor (RT) instability at an embedded, or classical, interface is examined in a series of experiments at the Nova laserfacility .[reference for Nova] These experiments focused on the transition from the linear to nonlinear regimes for both single- and multimode initialperturbations. The development of a single mode at the embedded interface is compared to its evolution at an ablation front and the effect of ablativestabilization is experimentally demonstrated. The multimode experiments have shown evidence of the process of bubble competition, whereinneighboring structures either continue to rise or are washed downstream in the flow depending upon their relative size. The experiments with simulations performed with either the LASNEX are comparedcode [G. B.Zimmerman and W. L. Kruer, Comments Plasma Phys. Controlled Fusion 2,51 (1975).], a two-dimensional Lagrangian radiation-hydrodynamics code, or CALE [R. Tipton, reference for CALE], a two-dimensional arbitrary Lagrange-Eulerian radiation-hydrodynamics code.
High Reynolds number decay of turbulent Taylor-Couette flow
NASA Astrophysics Data System (ADS)
Verschoof, Ruben A.; Huisman, Sander G.; van der Veen, Roeland C. A.; Sun, Chao; Lohse, Detlef
2015-11-01
We study the decay of high-Reynolds number turbulence in a Taylor-Couette facility for pure inner cylinder rotation. The rotation of the inner cylinder (Rei = 2 ×106) is suddenly decelerated as fast as possible, thus removing the energy input within seconds. Local velocity measurements show that the decay in this wall-bounded inhomogeneous flow is faster than observed for homogeneous isotropic turbulent flows, due to the strong viscous drag applied by the inner and outer cylinder surfaces. We found that the decay over time can be described with the differential equation Re . (t) =cf (Re)Re2 , where the effects of the walls are included through the friction coefficient. A self-similar behavior of the azimuthal velocity is found: its normalized velocity profile as a function of the radius collapses over time during the decay process.
Logarithmic Boundary Layers in Strong Taylor-Couette Turbulence
NASA Astrophysics Data System (ADS)
Lohse, Detlef; Huisman, Sander; Ostilla, Rodolfo; Scharnowski, Sven; Cierpka, Christian; Kähler, Christian; Verzicco, Roberto; Sun, Chao; Grossmann, Siegfried
2013-11-01
We provide direct measurements of boundary layer profiles in highly turbulent Taylor-Couette flow up to Re = 2 ×106 using high-resolution particle image velocimetry and particle tracking velocimetry, complemented by DNS data on the same system up to Re =105 . We find that the mean azimuthal velocity profile at the inner and outer cylinder can be fitted by the von Kármán log law, but with corrections due to the curvature of the cylinder, which we theoretically account for, based on the Navier-Stokes equation and a closure assumption for the turbulent diffusivity. In particular, we study how these corrections depend on the cylinder radius ratio and show that they are different for the boundary layers at the inner and at the outer cylinder.
Logarithmic Boundary Layers in Strong Taylor-Couette Turbulence
NASA Astrophysics Data System (ADS)
Huisman, Sander G.; Scharnowski, Sven; Cierpka, Christian; Kähler, Christian J.; Lohse, Detlef; Sun, Chao
2013-06-01
We provide direct measurements of the boundary layer properties in highly turbulent Taylor-Couette flow up to Re=2×106 (Ta=6.2×1012) using high-resolution particle image velocimetry and particle tracking velocimetry. We find that the mean azimuthal velocity profile at the inner and outer cylinder can be fitted by the von Kármán log law u+=1/κlny++B. The von Kármán constant κ is found to depend on the driving strength Ta and for large Ta asymptotically approaches κ≈0.40. The variance profiles of the local azimuthal velocity have a universal peak around y+≈12 and collapse when rescaled with the driving velocity (and not with the friction velocity), displaying a log dependence of y+ as also found for channel and pipe flows.
Recovering network topologies via Taylor expansion and compressive sensing.
Li, Guangjun; Wu, Xiaoqun; Liu, Juan; Lu, Jun-an; Guo, Chi
2015-04-01
Gaining knowledge of the intrinsic topology of a complex dynamical network is the precondition to understand its evolutionary mechanisms and to control its dynamical and functional behaviors. In this article, a general framework is developed to recover topologies of complex networks with completely unknown node dynamics based on Taylor expansion and compressive sensing. Numerical simulations illustrate the feasibility and effectiveness of the proposed method. Moreover, this method is found to have good robustness to weak stochastic perturbations. Finally, the impact of two major factors on the topology identification performance is evaluated. This method provides a natural and direct point to reconstruct network topologies from measurable data, which is likely to have potential applicability in a wide range of fields. PMID:25933650
Qualitative and quantitative features of Rayleigh-Taylor mixing dynamics
NASA Astrophysics Data System (ADS)
Bhowmick, Aklant; Abarzhi, Snezhana; Ramaprabhu, Praveen; Karkhanis, Varad; Lawrie, Andrew; RTI Collaboration
2015-11-01
We consider dynamics of Rayleigh-Taylor (RT) flow in a large aspect ratio three-dimensional domain with square symmetry in the plane for fluids with contrasting densities. In order to quantify the interface evolution from a small amplitude single-mode initial perturbation to advanced stage of RT mixing, we apply numerical simulations using the MOBILE code, theoretical analyses, including group theory and momentum model, as well as parameters describing the interplay between acceleration and turbulence. We find: In RT flow, the fluid motion is intense near the interface and is negligible far from the interface. At late times the growth rates of RT bubbles and spikes may increase without a corresponding increase of length-scales in the direction normal to acceleration. The parameters describing the interplay between acceleration and turbulence in RT mixing are shown to scale well with the flow Reynolds number and Froude number.
Nonlinear saturation amplitude of cylindrical Rayleigh—Taylor instability
NASA Astrophysics Data System (ADS)
Liu, Wan-Hai; Yu, Chang-Ping; Ye, Wen-Hua; Wang, Li-Feng
2014-09-01
The nonlinear saturation amplitude (NSA) of the fundamental mode in the classical Rayleigh—Taylor instability with a cylindrical geometry for an arbitrary Atwood number is analytically investigated by considering the nonlinear corrections up to the third order. The analytic results indicate that the effects of the initial radius of the interface (r0) and the Atwood number (A) play an important role in the NSA of the fundamental mode. The NSA of the fundamental mode first increases gently and then decreases quickly with increasing A. For a given A, the smaller the r0/λ (λ is the perturbation wavelength), the larger the NSA of the fundamental mode. When r0/λ is large enough (r0 ≫ λ), the NSA of the fundamental mode is reduced to the prediction in the previous literatures within the framework of the third-order perturbation theory.
Size invariance of the granular Rayleigh-Taylor instability
NASA Astrophysics Data System (ADS)
Vinningland, Jan Ludvig; Johnsen, Øistein; Flekkøy, Eirik G.; Toussaint, Renaud; Måløy, Knut Jørgen
2010-04-01
The size scaling behavior of the granular Rayleigh-Taylor instability [J. L. Vinningland , Phys. Rev. Lett. 99, 048001 (2007)] is investigated experimentally, numerically, and theoretically. An upper layer of grains displaces a lower gap of air by organizing into dense fingers of falling grains separated by rising bubbles of air. The dependence of these structures on the system and grain sizes is investigated. A spatial measurement of the finger structures is obtained by the Fourier power spectrum of the wave number k . As the size of the grains increases the wave number decreases accordingly which leaves the dimensionless product of wave number and grain diameter, dk , invariant. A theoretical interpretation of the invariance, based on the scaling properties of the model equations, suggests a gradual breakdown of the invariance for grains smaller than ˜70μm or greater than ˜570μm in diameter.
Suppression of Rayleigh-Taylor instabilities in Z-pinches
NASA Astrophysics Data System (ADS)
Zhigalin, A. S.; Rousskikh, A. G.; Baksht, R. B.; Chaikovsky, S. A.; Labetskaya, N. A.; Oreshkin, V. I.
2015-06-01
Experiments on studying the stability of Z-pinch compression were carried out at a current of 450 kA with a build-up time of 450 ns. The plasma shell of the pinches was formed by evaporating the electrode material in the process of vacuum arc burning. The Rayleigh-Taylor (RT) instabilities were suppressed using the regime of arc combustion on the surface of one of the electrodes in the high-voltage gap in which the pinch was positioned. As a result of free plasma discharge, the radial density distribution was formed such that the plasma concentration increased from the outer boundary to the shell axis. The experiments demonstrated that such an initial radial density distribution almost completely suppresses of the RT instability.
Shercliff layers in strongly magnetic cylindrical Taylor-Couette flow
NASA Astrophysics Data System (ADS)
Hollerbach, Rainer; Hulot, Deborah
2016-07-01
We numerically compute the axisymmetric Taylor-Couette flow in the presence of axially periodic magnetic fields, with Hartmann numbers up to Ha2 =107. The geometry of the field singles out special field lines on which Shercliff layers form. These are simple shear layers for insulating boundaries, versus super-rotating or counter-rotating layers for conducting boundaries. Some field configurations have previously studied spherical analogs, but fundamentally new configurations also exist, having no spherical analogs. Finally, we explore the influence of azimuthal fields Bϕ ∼r-1eˆϕ on these layers, and show that the flow is suppressed for conducting boundaries, but enhanced for insulating boundaries. xml:lang="fr"
Taylor dispersion in equilibrium gradient focusing at steady state.
Ivory, Cornelius F
2015-03-01
An analytic expression is presented for the effective dispersion coefficient in the case where a solute is focused in a parabolic flow against a linear gradient in a restoring force. This expression was derived by employing a minor variation on the method of moments used by Aris in his development of the dispersion coefficients for a time-dependent, isocratic system. In the present case, dispersion is controlled by two dimensionless groups, a Peclet number which is proportional to the parabolic component of the flow, and a gradient number which is proportional to the slope of the restoring force. These results confirm that the Aris-Taylor expression for the dispersion coefficient should not be applied in cases where a solute is focused to a stationary steady state. PMID:25521436
Symmetry and stability in Taylor-Couette flow
NASA Technical Reports Server (NTRS)
Golubitsky, M.; Stewart, I.
1986-01-01
The flow of a fluid between concentric rotating cylinders (the Taylor problem) is studied by exploiting the symmetries of the system. The Navier-Stokes equations, linearized about Couette flow, possess two zero and four purely imaginary eigenvalues at a suitable value of the speed of rotation of the outer cylinder. There is thus a reduced bifurcation equation on a six-dimensonal space which can be shown to commute with an action of the symmetry group 0(2) x S0(2). The group structure is used to analyze this bifurcation equation in the simplest (nondegenerate) case, and to compute the stabilities of solutions. In particular, when the outer cylinder is counterrotated, transitions which seem to agree with recent experiments of Andereck, Liu, and Swinney (1984) are obtained. It is also possible to obtain the 'main sequence' in this model. This sequence is normally observed in experiments when the outer cylinder is held fixed.
Recovering network topologies via Taylor expansion and compressive sensing
Li, Guangjun; Liu, Juan E-mail: liujuanjp@163.com; Wu, Xiaoqun E-mail: liujuanjp@163.com; Lu, Jun-an; Guo, Chi
2015-04-15
Gaining knowledge of the intrinsic topology of a complex dynamical network is the precondition to understand its evolutionary mechanisms and to control its dynamical and functional behaviors. In this article, a general framework is developed to recover topologies of complex networks with completely unknown node dynamics based on Taylor expansion and compressive sensing. Numerical simulations illustrate the feasibility and effectiveness of the proposed method. Moreover, this method is found to have good robustness to weak stochastic perturbations. Finally, the impact of two major factors on the topology identification performance is evaluated. This method provides a natural and direct point to reconstruct network topologies from measurable data, which is likely to have potential applicability in a wide range of fields.
Plasma transport driven by the Rayleigh-Taylor instability
NASA Astrophysics Data System (ADS)
Ma, X.; Delamere, P. A.; Otto, A.
2016-06-01
Two important differences between the giant magnetospheres (i.e., Jupiter's and Saturn's magnetospheres) and the terrestrial magnetosphere are the internal plasma sources and the fast planetary rotation. Thus, there must be a radially outward flow to transport the plasma to avoid infinite accumulation of plasma. This radial outflow also carries the magnetic flux away from the inner magnetosphere due to the frozen-in condition. As such, there also must be a radial inward flow to refill the magnetic flux in the inner magnetosphere. Due to the similarity between Rayleigh-Taylor (RT) instability and the centrifugal instability, we use a three-dimensional RT instability to demonstrate that an interchange instability can form a convection flow pattern, locally twisting the magnetic flux, consequently forming a pair of high-latitude reconnection sites. This process exchanges a part of the flux tube, thereby transporting the plasma radially outward without requiring significant latitudinal convection of magnetic flux in the ionosphere.
Linear analysis of incompressible Rayleigh-Taylor instability in solids.
Piriz, A R; Cela, J J López; Tahir, N A
2009-10-01
The study of the linear stage of the incompressible Rayleigh-Taylor instability in elastic-plastic solids is performed by considering thick plates under a constant acceleration that is also uniform except for a small sinusoidal ripple in the horizontal plane. The analysis is carried out by using an analytical model based on the Newton second law and it is complemented with extensive two-dimensional numerical simulations. The conditions for marginal stability that determine the instability threshold are derived. Besides, the boundary for the transition from the elastic to the plastic regime is obtained and it is demonstrated that such a transition is not a sufficient condition for instability. The model yields complete analytical solutions for the perturbation amplitude evolution and reveals the main physical process that governs the instability. The theory is in general agreement with the numerical simulations and provides useful quantitative results. Implications for high-energy-density-physics experiments are also discussed. PMID:19905434
Adaptive wavelet collocation method simulations of Rayleigh-Taylor instability
NASA Astrophysics Data System (ADS)
Reckinger, S. J.; Livescu, D.; Vasilyev, O. V.
2010-12-01
Numerical simulations of single-mode, compressible Rayleigh-Taylor instability are performed using the adaptive wavelet collocation method (AWCM), which utilizes wavelets for dynamic grid adaptation. Due to the physics-based adaptivity and direct error control of the method, AWCM is ideal for resolving the wide range of scales present in the development of the instability. The problem is initialized consistent with the solutions from linear stability theory. Non-reflecting boundary conditions are applied to prevent the contamination of the instability growth by pressure waves created at the interface. AWCM is used to perform direct numerical simulations that match the early-time linear growth, the terminal bubble velocity and a reacceleration region.
Fabrication of microcoined metal foil Rayleigh-Taylor targets
NASA Astrophysics Data System (ADS)
Randall, Greg; Vecchio, James; Fitzsimmons, Paul; Knipping, Jack; Wall, Don; Vu, Matthew; Giraldez, Emilio; Remington, Tane; Blue, Brent; Farrell, Michael; Nikroo, Abbas
2013-03-01
Rippled metal foils are currently sought for high strain rate material strength studies. For example, the growth of these ripples by the Rayleigh-Taylor instability after a laser-induced ramped compression yields strength behavior at extremely high strain rate. Because metals of interest (iron, tantalum, steel, etc.) typically cannot be diamond turned, we employ a microcoining process to imprint the ~ 5 μm deep by ~ 50 μm long ripples into the metal surface. The process consists of nitriding a steel die, diamond turning the die, and then pressing the die into a polished metal foil of choice (Seugling et al., Proc EUSPEN Int. Conference, 2010). This work details recent process developments, characterization techniques, and important physics for fabrication of these rippled metal targets.
Collisional effects on Rayleigh-Taylor-induced magnetic fields
Manuel, M. J.-E.; Flaig, M.; Plewa, T.; Li, C. K.; Séguin, F. H.; Frenje, J. A.; Casey, D. T.; Petrasso, R. D.; Hu, S. X.; Betti, R.; Hager, J.; Meyerhofer, D. D.; Smalyuk, V.
2015-05-15
Magnetic-field generation from the Rayleigh-Taylor (RT) instability was predicted more than 30 years ago, though experimental measurements of this phenomenon have only occurred in the past few years. These pioneering observations demonstrated that collisional effects are important to B-field evolution. To produce fields of a measurable strength, high-intensity lasers irradiate solid targets to generate the nonaligned temperature and density gradients required for B-field generation. The ablation process naturally generates an unstable system where RT-induced magnetic fields form. Field strengths inferred from monoenergetic-proton radiographs indicate that in the ablation region diffusive effects caused by finite plasma resistivity are not negligible. Results from the first proof-of-existence experiments are reviewed and the role of collisional effects on B-field evolution is discussed in detail.
Code of Federal Regulations, 2011 CFR
2011-01-01
... to the Former Liberian Regime of Charles Taylor Presidential Documents Other Presidential Documents... of Charles Taylor On July 22, 2004, by Executive Order 13348, the President declared a national... to the former Liberian regime of Charles Taylor, pursuant to the International Emergency...
Lesbis sustineo! Naiad press authors remember Barbara Grier.
Cantrell, Jaime
2014-01-01
Drawing from semi-structured interviews with some of Naiad Press's most celebrated women, including Katherine V. Forrest, Barbara's supervising editor at Naiad from 1983-1993; Sheila Ortiz Taylor, author of what is considered by many to be the first lesbian novel with a Chicana heroine; and the incomparable Lee Lynch, this work aims to sustain an ongoing remembrance of Grier's life and work by encouraging memory exploration--a symphonic blending of the printed and spoken word. PMID:25298097
Nature and significance of Austin-Taylor unconformity on western margin of east Texas basin
Surles, M.A. Jr.
1984-04-01
The Taylor Marl unconformably overlies the Austin Chalk on the western margin of the East Texas basin. Along this contact, up to 275 ft (84 m) of upper Austin is missing in the Waco area and up to 450 ft (137 m) in Bell County. However, the Austin Chalk appears to have been more-or-less uniformly deposited throughout the study area. Apparently regional uplift caused a regression that terminated Austin deposition and was related to the erosion of the upper Chalk. While the unconformity is areally extensive, slightly angular, and accounts for a relatively long period of time, the mechanism of erosion that caused the unconformity is still uncertain. Erosion was terminated by the deposition of the lower Taylor Marl. Taylor A, the lowermost subdivision of the lower Taylor, was deposited in a near-shore environment that was highly variable. Of particular interest is the relationship of this unconformity to structure and probably to oil occurrence in the Austin Chalk in McLennan and Falls Counties. Major Austin fracturing, which apparently does not extend into the Taylor in Falls County, clearly indicates that structure in the Chalk, at least in part, antedates Taylor deposition. Oil occurrence in the Chalk is clearly related to fracturing and probably is localized by post-Austin-pre-Taylor fracture systems.
NASA Astrophysics Data System (ADS)
Tirani, M. Dadkhah; Sohrabi, F.; Almasieh, H.; Kajani, M. Tavassoli
2015-10-01
In this paper, a collocation method based on Taylor polynomials is developed for solving systems linear differential-difference equations with variable coefficients defined in large intervals. By using Taylor polynomials and their properties in obtaining operational matrices, the solution of the differential-difference equation system with given conditions is reduced to the solution of a system of linear algebraic equations. We first divide the large interval into M equal subintervals and then Taylor polynomials solutions are obtained in each interval, separately. Some numerical examples are given and results are compared with analytical solutions and other techniques in the literature to demonstrate the validity and applicability of the proposed method.
Implications of the Monin-Yaglom relation for Rayleigh-Taylor turbulence.
Soulard, Olivier
2012-12-21
The aim of this letter is to assess existing theories for Rayleigh-Taylor small turbulent scales. For this purpose, we propose to adapt the Monin-Yaglom relation to the Rayleigh-Taylor turbulence context. A special emphasis is put on the inhomogeneity of the flow and on the effect of buoyancy forces. This relation is then used to show that, among existing theories, the standard Kolmogorov-Obukhov theory should apply to Rayleigh-Taylor turbulence in the limit of a large Reynolds number, large times, and small scales. PMID:23368468
Experimental Investigation of the Rayleigh-Taylor Instability
NASA Astrophysics Data System (ADS)
White, Jeremy
2011-12-01
A series of experiments have been carried out to study the behavior of the Rayleigh-Taylor instability. The experiments cover a wide range of Atwood (A = (rho2-rho1)/(rho 2-rho1)) numbers, 0.28 ≤ A ≤ 1 using immiscible fluids, with Reynolds numbers spanning four orders of magnitude, ˜ 10 ≤ Re ≤ 10000. Multiple 2D interface shapes have been studied along with a single 3D configuration. The unique properties of magnetorheological fluids are exploited to generate well defined, static initial conditions for both single and multi-mode sinusoidal perturbations as well as isolated wavelengths of single-mode perturbations protruding from flat interfaces. The magnetic properties of the fluid are used to hold these shapes static prior to running, as well as to suspend them above a lighter fluid to allow gravity to provide acceleration to drive the mixing. The 2D experimental results corroborate some of the limitations of the non-linear analytical models, which have been recently investigated numerically, as well as observed in 3D experiments, but not reported in 2D experiments before. The unbounded growth of the Rayleigh-Taylor spikes at late times has been experimentally confirmed for both the 3D condition, where this is predicted to occur for all Atwood numbers, and for the A = 1 limit in the 2D configuration. Preliminary testing with multi-mode interface shapes with high viscosity, high surface tension MR fluids demonstrate the feasibility of extending this unique experimental technique to the more complicated multi-mode/broadband initial conditions more commonly present in applications. Further extension to lower viscosity and surface tension MR fluids for higher Reynolds number flows has proven difficult with the experimental design, yet has revealed the future changes that will be needed to apply this unique experimental idea to the study of the turbulent mix regime. Finally, 3D simulations using the 2D experimental conditions have demonstrated the importance
Numerical and experimental studies of magnetic Rayleigh-Taylor instabilities in solid liners
Faehl, R.J.; Atchison, W.L.; Reinovsky, R.E.; Morgan, D.V.
1997-12-31
The authors have studied the nonlinear evolution of Magnetic Rayleigh-Taylor (MRT) instability in solid aluminum liners. Two-dimensional MHD modeling of the configuration have been performed using the measured current pulseform of the PEGASUS II capacitor bank as a magnetic field source. The liner configuration consisted of a solid aluminum annulus 20 mm long and 0.4 mm thick. The outer surface of the liner was machined with a sinusoidal ripple. Half of the liner was scribed with one wavelength, the other half with another wavelength. A series of experiments was conducted with a smooth surface and ripple wavelengths of 0.5, 0.75, and 2.0 mm. The peak-to-peak ripple amplitude was varied between 0.025 and 0.10 mm, but the ratio of the initial amplitude to wavelength never exceeded 7%. Diagnostics consisted of radiography, a center-conductor B-dot probe, and transmission line pulsed power diagnostics. The inner surfaces of the liners were coated with a thin film of gold (Au) to permit measurement of material deformation at various stages of the instability growth. Three radiographs, at different times, were taken for each experiment. The center-conductor magnetic probe was used to measure the magnetic field penetration through the liner. Initial comparisons between the data and the MHD calculations showed excellent agreement with respect to nonlinear instability growth and with the time of field rupture of the liner.
Magneto-stratigraphic studies in Neogene deposits of Taylor Valley and McMurdo Sound, Antarctica.
Elston, D.P.; Bressler, S.L.
1981-01-01
Magnetic polarity and susceptibility zonations obtained from drill cores have served to refine temporal correlations in glaciogenic sections cored in eastern Taylor Valley. The zonations have led to a better understanding of the glacial and structural history for an interval of time that extends from the late Miocene (about 7Ma) to perhaps near the end of the Pliocene (approx 2.4-1.8Ma). However polarity data from a core drilled in McMurdo Sound (hole MSSTS-1) were found to be less useful. In this core, normal and reverse polarity deposits of Holocene, Pleistocene, and Pliocene age are nearly 40m thick and appear to uncomformably overlie strata assigned to the middle Miocene on the basis of a reworked fauna and flora. Gaps in the stratigraphic coverage of the Miocene strata, and two intervals in which the magnetisation post-dates deposition, however, have made development of a reliable polarity zonation impossible, and no firm correlation could be made with the magnetic polarity time scale. -Authors
Weakly nonlinear analysis of the Saffman-Taylor problem
NASA Astrophysics Data System (ADS)
Miranda, Jose A.
The Saffman-Taylor viscous fingering instability occurs when a less viscous fluid displaces a more viscous one between narrowly spaced parallel plates in a Hele-Shaw cell. Experiments in radial and rectangular flow geometries form finger-like patterns, in which fingers of different lengths compete, spread and split. Our weakly nonlinear analysis of the instability predicts these phenomena, which are beyond the scope of linear stability theory. Finger competition arises through enhanced growth of sub-harmonic perturbations, while spreading and splitting occur through the growth of harmonic modes. Nonlinear mode-coupling enhances the growth of these specific perturbations with appropriate relative phases, as we demonstrate through a symmetry analysis of the mode coupling equations. We extend our mode coupling theory to include the situation in which one of the fluids is a ferrofluid and a magnetic field is applied normal to the Hele-Shaw cell. Our analysis indicates that the onset of interface symmetry breaking observed in experiments involving ferrofluids depends on viscosity contrast, not on the applied magnetic field. We also show how magnetic fields lead to finger tip-splitting.
Dynamics of axially localized states in Taylor-Couette flows.
Lopez, Jose M; Marques, Francisco
2015-05-01
We present numerical simulations of the flow confined in a wide gap Taylor-Couette system, with a rotating inner cylinder and variable length-to-gap aspect ratio. A complex experimental bifurcation scenario differing from the classical Ruelle-Takens route to chaos has been experimentally reported in this geometry. The wavy vortex flow becomes quasiperiodic due to an axisymmetric very low frequency mode. This mode plays a key role in the dynamics of the system, leading to the occurrence of chaos via a period-doubling scenario. Further increasing the rotation of the inner cylinder results in the appearance of a new flow pattern which is characterized by large amplitude oscillations localized in some of the vortex pairs. The purpose of this paper is to study numerically the dynamics of these axially localized states, paying special attention to the transition to chaos. Frequency analysis from time series simultaneously recorded at several points has been applied in order to identify the flow transitions taking place. It has been found that the very low frequency mode is essential to explain the behavior associated with the different transitions towards chaos including localized states. PMID:26066253
Reynolds and Atwood Numbers Effects on Homogeneous Rayleigh Taylor Instability
NASA Astrophysics Data System (ADS)
Aslangil, Denis; Livescu, Daniel; Banerjee, Arindam
2015-11-01
The effects of Reynolds and Atwood numbers on turbulent mixing of a heterogeneous mixture of two incompressible, miscible fluids with different densities are investigated by using high-resolution Direct Numerical Simulations (DNS). The flow occurs in a triply periodic 3D domain, with the two fluids initially segregated in random patches, and turbulence is generated in response to buoyancy. In turn, stirring produced by turbulence breaks down the scalar structures, accelerating the molecular mixing. Statistically homogeneous variable-density (VD) mixing, with density variations due to compositional changes, is a basic mixing problem and aims to mimic the core of the mixing layer of acceleration driven Rayleigh Taylor Instability (RTI). We present results covering a large range of kinematic viscosity values for density contrasts including small (A =0.04), moderate (A =0.5), and high (A =0.75 and 0.9) Atwood numbers. Particular interest will be given to the structure of the turbulence and mixing process, including the alignment between various turbulence and scalar quantities, as well as providing fidelity data for verification and validation of mix models. Arindam Banerjee acknowledges support from NSF CAREER award # 1453056.
Cylindrical effects in weakly nonlinear Rayleigh-Taylor instability
NASA Astrophysics Data System (ADS)
Liu, Wan-Hai; Ma, Wen-Fang; Wang, Xu-Lin
2015-01-01
The classical Rayleigh-Taylor instability (RTI) at the interface between two variable density fluids in the cylindrical geometry is explicitly investigated by the formal perturbation method up to the second order. Two styles of RTI, convergent (i.e., gravity pointing inward) and divergent (i.e., gravity pointing outwards) configurations, compared with RTI in Cartesian geometry, are taken into account. Our explicit results show that the interface function in the cylindrical geometry consists of two parts: oscillatory part similar to the result of the Cartesian geometry, and non-oscillatory one contributing nothing to the result of the Cartesian geometry. The velocity resulting only from the non-oscillatory term is followed with interest in this paper. It is found that both the convergent and the divergent configurations have the same zeroth-order velocity, whose magnitude increases with the Atwood number, while decreases with the initial radius of the interface or mode number. The occurrence of non-oscillation terms is an essential character of the RTI in the cylindrical geometry different from Cartesian one. Project supported by the National Basic Research Program of China (Grant No. 10835003), the National Natural Science Foundation of China (Grant No. 11274026), the Scientific Research Foundation of Mianyang Normal University, China (Grant Nos. QD2014A009 and 2014A02), and the National High-Tech ICF Committee.
Preliminary survey report, Didier Taylor Refractories Corporation Plant, Newtown, Ohio
Mahon, R.D.
1981-10-20
An on-site visit was made to the Didier Taylor Refractories Corporation located in Newtown, Ohio for the purpose of evaluating control methods instituted to protect workers from hazardous conditions. Raw materials were received at this location in bags and canisters. The bags were opened in an area with dual-pull exhaust ventilation from two sides. Several St. Regis single spout packers with local exhaust systems were also used at this facility. All exhaust ducts connected to a large Kirk and Blum dry-bag collector located adjacent to the building. Some molding and casting work was done at this facility, but no particularly significant health hazard controls were noted for the process. The product line included bricks, patches, ramming mixes, cements, castables, plastics, and miscellaneous items. Plaster of paris and thermo setting plastics were used as mold materials. Slip mixes involved a wide range of chemical compounds. Plans were made to conduct a walk-through preliminary-type survey of the location at a later date. An in-depth assessment of portions of the facility and operations may be decided upon at that time.
Magneto-Rayleigh-Taylor instability in solid media
Sun, Y. B.; Piriz, A. R.
2014-07-15
A linear analysis of the magneto-Rayleigh-Taylor instability at the interface between a Newtonian fluid and an elastic-plastic solid is performed by considering a uniform magnetic B{sup →}, parallel to the interface, which has diffused into the fluid but not into the solid. It is found that the magnetic field attributes elastic properties to the viscous fluid which enhance the stability region by stabilizing all the perturbation wavelengths shorter than λ{sub 0}∝B{sup 2} for any initial perturbation amplitude. Longer wavelengths are stabilized by the mechanical properties of the solid provided that the initial perturbation wavelength is smaller than a threshold value determined by the yield strength and the shear modulus of the solid. Beyond this threshold, the amplitude grows initially with a growth rate reduced by the solid strength properties. However, such properties do not affect the asymptotic growth rate which is only determined by the magnetic field and the fluid viscosity. The described physical situation intends to resemble some of the features present in recent experiments involving the magnetic shockless acceleration of flyers plates.
Rayleigh-Taylor stabilization by material strength at Mbar pressures
Park, H; Lorenz, K T; Cavallo, R M; Pollaine, S M; Prisbrey, S T; Remington, B A; Rudd, R E; Becker, R C; Bernier, J V
2009-05-27
Studies of solid-state material dynamics at high pressures ({approx}1 Mbar) and ultrahigh strain rates (>10{sup 6} s{sup -1}) are performed using a unique laser based, quasi-isentropic high-pressure acceleration platform. Vanadium foils with pre-imposed sinusoidal ripples are accelerated in the solid state with this ramped high pressure drive. This causes Rayleigh-Taylor (RT) instability growth at the interface, where the rate of growth is sensitive to the solid-state material properties. The RT growth history is measured by face-on radiography using synchronized laser-driven x-ray backlighters at the Omega Laser. The experimental results are compared with 2D hydrodynamics simulations utilizing constitutive models of high pressure material strength. We find that the vanadium strength increases by a factor of 3.5-4 at peak pressure, compared to its ambient (undriven) strength. Both pressure hardening and strain rate hardening are the suggested cause for this increase in strength. An analysis treating strength as an effective lattice viscosity finds that a viscosity of {approx}400 poise is required to reproduce our RT data.
Rayleigh-Taylor Unstable Flames -- Fast or Faster?
NASA Astrophysics Data System (ADS)
Hicks, E. P.
2015-04-01
Rayleigh-Taylor (RT) unstable flames play a key role in the explosions of supernovae Ia. However, the dynamics of these flames are still not well understood. RT unstable flames are affected by both the RT instability of the flame front and by RT-generated turbulence. The coexistence of these factors complicates the choice of flame speed subgrid models for full-star Type Ia simulations. Both processes can stretch and wrinkle the flame surface, increasing its area and, therefore, the burning rate. In past research, subgrid models have been based on either the RT instability or turbulence setting the flame speed. We evaluate both models, checking their assumptions and their ability to correctly predict the turbulent flame speed. Specifically, we analyze a large parameter study of 3D direct numerical simulations of RT unstable model flames. This study varies both the simulation domain width and the gravity in order to probe a wide range of flame behaviors. We show that RT unstable flames are different from traditional turbulent flames: they are thinner rather than thicker when turbulence is stronger. We also show that none of the several different types of turbulent flame speed models accurately predicts measured flame speeds. In addition, we find that the RT flame speed model only correctly predicts the measured flame speed in a certain parameter regime. Finally, we propose that the formation of cusps may be the factor causing the flame to propagate more quickly than predicted by the RT model.
Modified Taylor reproducing formulas and h-p clouds
NASA Astrophysics Data System (ADS)
Zuppa, Carlos
2008-03-01
We study two different approximations of a multivariate function f by operators of the form sum_{iD1}^{N}mathcal{T}_{r}[f,x_{i}](x) mathcal{W} _{i}(x) , where \\{mathcal{W}_{i}\\} is an m -reproducing partition of unity and mathcal{T}_{r}[f,x_{i}](x) are modified Taylor polynomials of degree r expanded at x_{i} . The first approximation was introduced by Xuli (2003) in the univariate case and generalized for convex domains by Guessab et al. (2005). The second one was introduced by Duarte (1995) and proved in the univariate case. In this paper, we first relax the Guessab's convexity assumption and we prove Duarte's reproduction formula in the multivariate case. Then, we introduce two related reproducing quasi-interpolation operators in Sobolev spaces. A weighted error estimate and Jackson's type inequalities for h-p cloud function spaces are obtained. Last, numerical examples are analyzed to show the approximative power of the method.
Non-equilibrium Thermodynamics of Rayleigh-Taylor Instability
NASA Astrophysics Data System (ADS)
Sengupta, Tapan K.; Sengupta, Aditi; Sengupta, Soumyo; Bhole, Ashish; Shruti, K. S.
2016-04-01
Here, the fundamental problem of Rayleigh-Taylor instability (RTI) is studied by direct numerical simulation (DNS), where the two air masses at different temperatures, kept apart initially by a non-conducting horizontal interface in a 2D box, are allowed to mix. Upon removal of the partition, mixing is controlled by RTI, apart from mutual mass, momentum, and energy transfer. To accentuate the instability, the top chamber is filled with the heavier (lower temperature) air, which rests atop the chamber containing lighter air. The partition is positioned initially at mid-height of the box. As the fluid dynamical system considered is completely isolated from outside, the DNS results obtained without using Boussinesq approximation will enable one to study non-equilibrium thermodynamics of a finite reservoir undergoing strong irreversible processes. The barrier is removed impulsively, triggering baroclinic instability by non-alignment of density, and pressure gradient by ambient disturbances via the sharp discontinuity at the interface. Adopted DNS method has dispersion relation preservation properties with neutral stability and does not require any external initial perturbations. The complete inhomogeneous problem with non-periodic, no-slip boundary conditions is studied by solving compressible Navier-Stokes equation, without the Boussinesq approximation. This is important as the temperature difference between the two air masses considered is high enough (Δ T = 70 K) to invalidate Boussinesq approximation. We discuss non-equilibrium thermodynamical aspects of RTI with the help of numerical results for density, vorticity, entropy, energy, and enstrophy.
The stability of Taylor-Couette flow with radial heating
NASA Astrophysics Data System (ADS)
Ali, Mohamed El-Sayed
The stability of circular Couette flow with radial heating across vertically oriented coaxial cylinders is investigated using linearized stability theory. The physical problem is governed by five parameters: the Taylor number Ta, the Groshof number G, the Prandtl number Pr, the cylinder aspect ration A, and the radius ratio eta. In the model infinite aspect ratio is assumed and critical stability boundaries are calculated for a conduction regime base flow. A rational analysis is made to derive the full governing perturbation equations and test flow stability subject to both axisymmetric and nonaxisymmetric disturbances. The flow may be driven to instability by competition between centrifugal, buoyancy, and shear force mechanisms. In spite of this complexity, the existence of solution symmetries of the perturbation equations with respect to the sense of radial heating and the sense of cylinder rotation are proven. The linear boundary-value problem defined by 16 first-order differential equations is solved using the software package SUPORT in combination with the nonlinear equation solver SNSQE. Critical stability boundaries at fixed Pr and eta were determined by searching for the minimum value of either Ta or G over all wavelengths K and mode numbers n.
Fundamental magneto-Rayleigh-Taylor Instability Growth Experiments
NASA Astrophysics Data System (ADS)
Sinars, D. B.; Peterson, K. J.; Vesey, R. A.; Jennings, C.; Herrmann, M. C.; McBride, R. D.; Martin, M. R.; Slutz, S. A.
2013-10-01
Sandia is investigating a magnetized liner inertial fusion concept that uses cylindrical Be or Al liners to compress magnetized and preheated fusion fuel. As part of this work, we have been studying the growth of instabilities in initially solid liners driven with 20-24 MA, 100-ns current pulses on the Z pulsed power facility. The magneto-Rayleigh-Taylor instability in particular can disrupt the plasma liner during its implosion. Previous experiments studied instability growth starting either from intentionally seeded single-mode perturbations or from diamond-turned best-finish surfaces. Here we report on experiments studying (1) the growth of intentionally seeded multi-mode perturbations, and (2) the growth from polished best-finish surfaces where the tooling mark orientation is changed from being predominantly azimuthal to axial. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's NNSA under contract DE-AC04-94AL85000.
Vlasov simulation of the Rayleigh-Taylor instability
NASA Astrophysics Data System (ADS)
Wada, Yasutaka; Umeda, Takayuki; Machida, Shinobu
2016-04-01
The Rayleigh-Taylor instability (RTI) develops at an interface between two fluids with different densities when an external force is applied from a heavy fluid to a light fluid. The RTI is seen as a secondary instability of the Kelvin-Helmholtz instability taking place at the magnetopause. The spatial scale of the secondary RTI is on the ion inertial scale or ion gyro scale where non-MHD effects are important. In the previous studies of ideal MHD simulations, the RTI develops symmetrically in the horizontal axis. On the other hand, previous hall-MHD and Finite-Larmor-Radius (FLR)-MHD simulations have shown that the RTI develops asymmetrically in the horizontal axis. In this study, basic processes of non-MHD scale RTI are of interest. We perform four-dimensional Vlasov simulations of the RTI with two spatial dimensions and two velocity dimensions. We vary the ratio of the ion inertial length and/or the ion gyro radius to the spatial scale of the density gradient layer, and discuss the effect of the non-MHD effects on the linear growth and nonlinear development of the RTI.
Magneto-Rayleigh-Taylor instability in solid media
NASA Astrophysics Data System (ADS)
Sun, Y. B.; Piriz, A. R.
2014-07-01
A linear analysis of the magneto-Rayleigh-Taylor instability at the interface between a Newtonian fluid and an elastic-plastic solid is performed by considering a uniform magnetic B →, parallel to the interface, which has diffused into the fluid but not into the solid. It is found that the magnetic field attributes elastic properties to the viscous fluid which enhance the stability region by stabilizing all the perturbation wavelengths shorter than λ 0 ∝ B 2 for any initial perturbation amplitude. Longer wavelengths are stabilized by the mechanical properties of the solid provided that the initial perturbation wavelength is smaller than a threshold value determined by the yield strength and the shear modulus of the solid. Beyond this threshold, the amplitude grows initially with a growth rate reduced by the solid strength properties. However, such properties do not affect the asymptotic growth rate which is only determined by the magnetic field and the fluid viscosity. The described physical situation intends to resemble some of the features present in recent experiments involving the magnetic shockless acceleration of flyers plates.
Taylor relaxation and λ decay of unbounded, freely expanding spheromaks
NASA Astrophysics Data System (ADS)
Yee, J.; Bellan, P. M.
2000-09-01
A magnetized coaxial gun is discharged into a much larger vacuum chamber and the subsequent evolution of the plasma is observed using high speed cameras and a magnetic probe array. Photographic results indicate four distinct regimes of operation, labeled I-IV, each possessing qualitatively different dynamics, with the parameter λgun=μ0Igun/Φbias determining the operative regime. Plasmas produced in Regime II are identified as detached spheromak configurations. Images depict a donut-like shape, while magnetic data demonstrate that a closed toroidal flux-surface topology is present. Poloidal flux amplification shows that Taylor relaxation mechanisms are at work. The spatial and temporal variation of plasma λ=μ0Jφ/Bφ indicate that the spheromak is decaying and expanding in a manner analogous to a self-similar expansion model proposed for interplanetary magnetic clouds. In Regime III, the plasma is unable to detach from the gun due to excess bias flux. Analysis of toroidal and poloidal flux as well as the λ profile shows that magnetic flux and helicity are confined within the gun for this regime.
Geometry Mediated Drag Reduction in Taylor-Couette Flows
NASA Astrophysics Data System (ADS)
Raayai, Shabnam; McKinley, Gareth
2015-11-01
Micro-scale ribbed surfaces have been shown to be able to modify surface properties such as skin friction on both natural and fabricated surfaces. Previous experiments have shown that ribbed surfaces can reduce skin friction in turbulent flow by up to 4-8% in the presence of zero or mild pressure gradients. Our previous computations have shown a substantial reduction in skin friction using micro-scaled ribs of sinusoidal form in high Reynolds number laminar boundary layer flow. The mechanism of this reduction is purely viscous, through a geometrically-controlled retardation of the flow in the grooves of the surface. The drag reduction achieved depends on the ratio of the amplitude to the wavelength of the surface features and can be presented as a function of the wavelength expressed in dimensionless wall units. Here we extend this work, both experimentally and numerically, to consider the effect of similar ribs on steady viscous flow between concentric cylinders (Taylor-Couette flow). For the experimental work, the inner rotating cylinder (rotor) is machined with stream-wise V-groove structures and experiments are performed with fluids of different viscosity to compare the measured frictional torques to the corresponding values on a smooth flat rotor as a measure of drag reduction. The numerical work is performed using the OpenFOAM®open source software to compare the results and understand the physical mechanisms underlying this drag reduction phenomenon.
Regimes of the magnetized Rayleigh{endash}Taylor instability
Winske, D.
1996-11-01
Hybrid simulations with kinetic ions and massless fluid electrons are used to investigate the linear and nonlinear behavior of the magnetized Rayleigh{endash}Taylor instability in slab geometry with the plasma subject to a constant gravity. Three regimes are found, which are determined by the magnitude of the complex frequency {omega}={omega}{sub {ital r}}+{ital i}{gamma}. For {vert_bar}{omega}{vert_bar}{lt}{Omega}{sub {ital i}}({Omega}{sub {ital i}}= ion gyrofrequency), one finds the typical behavior of the usual fluid regime, namely the development of {open_quote}{open_quote}mushroom-head{close_quote}{close_quote} spikes and bubbles in the density and a strongly convoluted boundary between the plasma and magnetic field, where the initial gradient is not relaxed much. A second regime, where {vert_bar}{omega}{vert_bar}{approximately}0.1{Omega}{sub {ital i}}, is characterized by the importance of the Hall term. Linearly, the developing flute modes are more finger-like and tilted along the interface; nonlinearly, clump-like structures form, leading to a significant broadening of the interface. The third regime is characterized by unmagnetized ion behavior, with {vert_bar}{omega}{vert_bar}{approximately}{Omega}{sub {ital i}}. Density clumps, rather than flutes, form in the linear stage, while nonlinearly, longer-wavelength modes that resemble those in fluid regime dominate. Finite Larmor radius stabilization of short-wavelength modes is observed in each regime. {copyright} {ital 1996 American Institute of Physics.}
Frictional drag reduction in bubbly Couette-Taylor flow
NASA Astrophysics Data System (ADS)
Murai, Yuichi; Oiwa, Hiroshi; Takeda, Yasushi
2008-03-01
Frictional drag reduction due to the presence of small bubbles is investigated experimentally using a Couette-Taylor flow system; i.e., shear flow between concentric cylinders. Torque and bubble behavior are measured as a function of Reynolds number up to Re =5000 while air bubbles are injected constantly and rise through an array of vortical cells. Silicone oil is used to avoid the uncertain interfacial property of bubbles and to produce nearly monosized bubble distributions. The effect of drag reduction on sensitivity and power gain are assessed. The sensitivity exceeds unity at Re <2000, proving that the effect of the reduction in drag is greater than that of the reduction in mixture density. This is due to the accumulation of bubbles toward the rotating inner cylinder, which is little affected by turbulence. The power gain, which is defined by the power saving from the drag reduction per the pumping power of bubble injection, has a maximum value of O(10) at higher Re numbers around 2500. An image processing measurement shows this is because of the disappearance of azimuthal waves when the organized bubble distribution transforms from toroidal to spiral modes. Moreover, the axial spacing of bubble clouds expands during the transition, which results in an effective reduction in the momentum exchange.
Rayleigh-Taylor Instability in non-premixed reacting flames.
NASA Astrophysics Data System (ADS)
Attal, Nitesh; Ramaprabhu, Praveen
2015-11-01
The Rayleigh-Taylor instability (RTI) occurs at a perturbed interface between fluids of different densities when a light fluid pushes a heavier fluid. The mixing driven by RTI affects several physical phenomena, such as Inertial Confinement Fusion, Supernovae detonation, centrifugal combustors and liquid rocket engines. The RTI in such flows is often coupled with chemical/nuclear reactions that may form complex density stratifications in the form of flames or ablative layers. We investigate such a non-premixed fuel-air interface subject to a constant acceleration and developing under the influence of chemical reactions using high-resolution, Navier-Stokes simulations. The H2 fuel is diluted with N2 to vary the density difference across the interface in thermal equilibrium (at 1000K). The intervening layer between fuel and air is subject to exothermic combustion reactions to form a flame. Following combustion, initially unstable fuel-air interfaces at an Atwood number (At) <0.5, transform into stable (fuel-flame) and unstable (flame-air) interfaces. We report on interfaces (At = 0.2 and 0.6) with single wavelength, sinusoidal perturbations and a broadband spectrum of multimode perturbations.
Nonaxisymmetric linear instability of cylindrical magnetohydrodynamic Taylor-Couette flow
NASA Astrophysics Data System (ADS)
Child, Adam; Kersalé, Evy; Hollerbach, Rainer
2015-09-01
We consider the nonaxisymmetric modes of instability present in Taylor-Couette flow under the application of helical magnetic fields, mainly for magnetic Prandtl numbers close to the inductionless limit, and conduct a full examination of marginal stability in the resulting parameter space. We allow for the azimuthal magnetic field to be generated by a combination of currents in the inner cylinder and fluid itself and introduce a parameter governing the relation between the strength of these currents. A set of governing eigenvalue equations for the nonaxisymmetric modes of instability are derived and solved by spectral collocation with Chebyshev polynomials over the relevant parameter space, with the resulting instabilities examined in detail. We find that by altering the azimuthal magnetic field profiles the azimuthal magnetorotational instability, nonaxisymmetric helical magnetorotational instability, and Tayler instability yield interesting dynamics, such as different preferred mode types and modes with azimuthal wave number m >1 . Finally, a comparison is given to the recent WKB analysis performed by Kirillov et al. [Kirillov, Stefani, and Fukumoto, J. Fluid Mech. 760, 591 (2014), 10.1017/jfm.2014.614] and its validity in the linear regime.
On the effects of microbubbles on Taylor Green vortex flow
NASA Astrophysics Data System (ADS)
Ferrante, Antonino; Elghobashi, Said E.
The paper describes a numerical study of the effects of microbubbles on the vorticity dynamics in a Taylor Green vortex flow (TGV) using the two-fluid approach. The results show that bubbles with a volume fraction {˜}10(-2) enhance the decay rate of the vorticity at the centre of the vortex. Analysis of the vorticity equation of the bubble-laden flow shows that the local positive velocity divergence of the fluid velocity, {bm nabla} {bm *} {bm U}, created in the vortex core by bubble clustering, is responsible for the vorticity decay. At the centre of the vortex, the vorticity omega_c(t) decreases nearly linearly with the bubble concentration C_m(t). Similarly, the enstrophy in the core of the vortex, omega(2(t)) , decays nearly linearly with C(2(t)) . The approximate mean-enstrophy equation shows that bubble accumulation in the high-enstrophy core regions produces a positive correlation between omega(2) and {bm nabla} {bm *} {bm U}, which enhances the decay rate of the mean enstrophy.
Effects of microbubbles on the Taylor-Green vortex flow
NASA Astrophysics Data System (ADS)
Ferrante, A.
2005-11-01
Numerical simulations of the Taylor-Green vortex (TGV) flow laden with microbubbles were performed to study the effects of microbubbles on a simple vortical flow using the two-fluid approach. The study was motivated by our DNS results of a spatially developing turbulent boundary layer laden with microbubbles [J. Fluid Mech. 503 (2004)] which showed that the presence of bubbles results in a local positive divergence of the fluid velocity, ∇.U. This velocity divergence displaces the near-wall quasi-streamwise vortical structures away from the wall, thus reducing the skin friction. In the present study, the continuity and momentum equations of both phases (fluid and bubbles) were numerically solved in a cubical domain. The results for Stokes number equal to 0.25 and bubbles volume fraction of 1% show that the magnitude of the vorticity at the center of the vortex decays faster than that of the single-phase flow. After 20 turnover times of the initial vortex, the magnitude of the vorticity at the center of the vortex becomes 30% smaller than that of the single-phase flow. Analysis of the vorticity equation shows that the local positive velocity divergence of the fluid velocity, ∇.U, created in the vortex core by the clustering of the bubbles, is responsible for the vorticity decay. Results for different Stokes numbers and bubbles volume fractions will be presented.
Transition and Turbulence Decay in the Taylor-Green Vortex
NASA Astrophysics Data System (ADS)
Grinstein, Fernando; Drikakis, Dimitris; Fureby, Christer; Youngs, David
2005-11-01
The Taylor-Green Vortex (TGV) is a fundamental case that has been traditionally used as prototype of vortex stretching and consequent production of small-scale eddies, to investigate the basic dynamics of transition to turbulence. As such, it is also a very convenient case in which to test the ability of explicit and implicit subgrid scale (SGS) modeling to simulate the basic laws of turbulence. We report on the performance of Monotone Integrated LES (MILES) in emulating the space/time development of transition to turbulence and self-similar decay in the TGV without resorting to an explicit SGS model. MILES based on various limiting algorithms, including Flux Corrected Transport, characteristics-based Godunov, Lagrange-Remap, and several other hybrid methods is tested and compared with a conventional (mixed) LES method combining one-equation eddy-viscosity and scale-similarity models. The agreement between MILES, mixed-model LES, and the previous DNS by Brachet et al. (1983) is quite good in estimating the time and height of the dissipation peak associated with the TGV inviscid instability.
Helical magnetorotational instability in magnetized Taylor-Couette flow
Liu Wei; Ji Hantao; Goodman, Jeremy; Herron, Isom
2006-11-15
Hollerbach and Ruediger have reported a new type of magnetorotational instability (MRI) in magnetized Taylor-Couette flow in the presence of combined axial and azimuthal magnetic fields. The salient advantage of this 'helical' MRI (HMRI) is that marginal instability occurs at arbitrarily low magnetic Reynolds and Lundquist numbers, suggesting that HMRI might be easier to realize than standard MRI (axial field only), and that it might be relevant to cooler astrophysical disks, especially those around protostars, which may be quite resistive. We confirm previous results for marginal stability and calculate HMRI growth rates. We show that in the resistive limit, HMRI is a weakly destabilized inertial oscillation propagating in a unique direction along the axis. But we report other features of HMRI that make it less attractive for experiments and for resistive astrophysical disks. Large axial currents are required. More fundamentally, instability of highly resistive flow is peculiar to infinitely long or periodic cylinders: finite cylinders with insulating endcaps are shown to be stable in this limit, at least if viscosity is neglected. Also, Keplerian rotation profiles are stable in the resistive limit regardless of axial boundary conditions. Nevertheless, the addition of a toroidal field lowers thresholds for instability even in finite cylinders.
Further evidence for the validity of the Taylor Aggression Paradigm.
Giancola, Peter R; Parrott, Dominic J
2008-01-01
The purpose of this study was to evaluate the validity of a modified version of the Taylor Aggression Paradigm (TAP) as a measure of direct physical aggression. Hypotheses were generated from recent theory pertinent to the categorization and measurement of aggressive behavior as well as widely supported effects of alcohol intoxication and gender on aggression. Participants were 328 (163 men and 165 women) healthy social drinkers between 21 and 35 years of age who completed self-report personality inventories designed to assess one's propensity toward direct physical aggression, verbal aggression, trait anger, and hostility. Following the consumption of either an alcohol or a placebo beverage, participants were tested on the TAP, in which mild electric shocks were received from, and administered to, a fictitious opponent during a competitive task. Direct physical aggression was operationalized as the shock intensities (i.e., first trial shock intensity, mean shock intensity, proportion of highest shock) administered to the fictitious opponent. Although all self-report measures were significantly associated with the three TAP indices, the associations involving physical aggression were strongest. In addition, self-report measures of physical aggression consistently predicted higher levels of aggression on the TAP indices in men, compared with women, and in intoxicated, relative to sober, participants. Taken as a whole, this pattern of findings provides further evidence for the validity of the TAP as a measure of direct physical aggression for men and women. PMID:17894385
On Taylor dispersion in liquid-cooled electronics applications
NASA Astrophysics Data System (ADS)
Tilley, B. S.
2013-11-01
We are interested in extending classical asymptotic approaches to allow for the spatial pattern wavenumber to vary on the macroscale variables and to find how changes in microstructure geometry affect macroscopic properties and transport. To this end, we consider here the thermal transport of a coolant through nonuniformly spaced laminates, as a simple model for heat sinks in electronics. Power is continuously being generated by the laminates, and the local rates of heat transport depend on convection, fluid inertia, buoyancy and Taylor dispersion in the coolant and conduction within both the fluid and the laminates. We find a coupled system of partial differential equations that describe the local microscale temperature and deviations from the Darcy pressure. Microscale values of all of these quantities are known in terms of the solutions to these effective eqautions. We are especially interested in geometries in the laminate spacing which allow for better thermal transport by the coolant for a prescribed power distribution. The choice of the channel geometries depend on the ability to transfer heat from the device to the enviornment, the orientation of the device with respect to gravity, and the available power needed to drive the fluid motion. This work is supported by a grant from the Air Force Office of Scientific Research, (Award No. FA9550-11-1-0197).
Saffman-Taylor streamers: mutual finger interaction in spark formation.
Luque, Alejandro; Brau, Fabian; Ebert, Ute
2008-07-01
Bunches of streamers form the early stages of sparks and lightning but theory presently concentrates on single streamers or on coarse approximations of whole breakdown trees. Here a periodic array of interacting streamer discharges in a strong homogeneous electric field is studied in density or fluid approximation in two dimensions. If the period of the streamer array is small enough, the streamers do not branch, but approach uniform translation. When the streamers are close to the branching regime, the enhanced field at the tip of the streamer is close to 2Einfinity, where Einfinity is the homogeneous field applied between the electrodes. We discuss a moving boundary approximation to the density model. This moving boundary model turns out to be essentially the same as the one for two-fluid Hele-Shaw flows. In two dimensions, this model possesses a known analytical solution. The shape of the two-dimensional interacting streamers in uniform motion obtained from the PDE simulations is actually well fitted by the analytically known "selected Saffman-Taylor finger." This finding helps to understand streamer interactions and raises new questions on the general theory of finger selection in moving boundary problems. PMID:18764034
An Instability in Stratified Taylor-Couette Flow
NASA Astrophysics Data System (ADS)
Swinney, Harry
2015-11-01
In the late 1950s Russell Donnelly began conducting experiments at the University of Chicago on flow between concentric rotating cylinders, and his experiments together with complementary theory by his collaborator S. Chandrasekhar did much to rekindle interest in the flow instability discovered and studied by G.I. Taylor (1923). The present study concerns an instability in a concentric cylinder system containing a fluid with an axial density gradient. In 2005 Dubrulle et al. suggested that a `stratorotational instability' (SRI) in this system could provide insight into instability and angular momentum transport in astrophysical accretion disks. In 2007 the stratorotational instability was observed in experiments by Le Bars and Le Gal. We have conducted an experiment on the SRI in a concentric cylinder system (radius ratio η = 0 . 876) with buoyancy frequency N / 2 π = 0.25, 0.50, or 0.75 Hz. For N = 0.75 Hz we observe the SRI onset to occur for Ωouter /Ωinner > η , contrary to the prediction of Shalybkov and Rüdiger. Research conducted with Bruce Rodenborn and Ruy Ibanez.
Transient growth in linearly stable Taylor-Couette flows
NASA Astrophysics Data System (ADS)
Maretzke, Simon; Hof, Björn; Avila, Marc
2014-03-01
Non-normal transient growth of disturbances is considered as an essential prerequisite for subcritical transition in shear flows, i.e. transition to turbulence despite linear stability of the laminar flow. In this work we present numerical and analytical computations of linear transient growth covering all linearly stable regimes of Taylor--Couette flow. Our numerical experiments reveal comparable energy amplifications in the different regimes. For high shear Reynolds numbers Re the optimal transient energy growth always follows a 2/3-scaling with Re, which allows for large amplifications even in regimes where the presence of turbulence remains debated. In co-rotating Rayleigh-stable flows the optimal perturbations become increasingly columnar in their structure, as the optimal axial wavenumber goes to zero. In this limit of axially invariant perturbations we show that linear stability and transient growth are independent of the cylinders' rotation-ratio and we derive a universal 2/3-scaling of optimal energy growth with Re using WKB-theory. Based on this, a semi-empirical formula for the estimation of linear transient growth valid in all regimes is obtained.