ERIC Educational Resources Information Center
Rossman, Allan; Utts, Jessica
2014-01-01
This article offers a transcript of author Allan Rossman's interview with Jessica Utts, Professor and Chair of Statistics at the University of California-Irvine. Utts is also a Fellow of the American Statistical Association and a recipient of a Founders Award from ASA. Additionally, she has been elected as President of ASA for the year 2016. The…
ERIC Educational Resources Information Center
Rossman, Allan; Utts, Jessica
2014-01-01
This article offers a transcript of author Allan Rossman's interview with Jessica Utts, Professor and Chair of Statistics at the University of California-Irvine. Utts is also a Fellow of the American Statistical Association and a recipient of a Founders Award from ASA. Additionally, she has been elected as President of ASA for the year 2016. The…
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…
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 Watkins/NASA 2017 Astronaut Candidate
2017-08-22
The ranks of America’s Astronaut Corps grew by a dozen today! The twelve new NASA Astronaut Candidates have reported for duty at the Johnson Space Center in Houston to begin two years of training. Before they got to Houston we video-chatted with them all; Caltech postdoctoral fellow Jessica Watkins talks about how she became interested in science, technology, engineering and math, why she wanted to become an astronaut and where she was when she got the news that she’d achieved her dream. Learn more about the new space heroes right here: nasa.gov/2017astronauts
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…
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…
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…
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…
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…
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…
ERIC Educational Resources Information Center
Update on Law-Related Education, 1987
1987-01-01
Offers a lesson designed to help students recognize a key philosophical principle embodied in the U.S. Constitution: that the consent of the governed is the ultimate source of authority in our political system. (JDH)
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.
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…
ERIC Educational Resources Information Center
Holland, Shannon L.
2006-01-01
Through a critical analysis of the public discourse surrounding the capture and rescue of Jessica Lynch, this essay investigates how Lynch's body "comes to matter" in political debates regarding women in combat. This article argues that popular representations of Lynch's natural femaleness rearticulate the seemingly biological distinctions between…
Impacts of the Jessica oil spill on intertidal and shallow subtidal plants and animals.
Edgar, Graham J; Kerrison, Linda; Shepherd, Scoresby A; Veronica Toral-Granda, M
2003-01-01
Densities of fishes, invertebrates and plants at rocky intertidal and shallow subtidal sites were censused 1-2 days prior to the Jessica oil spill and compared with information obtained for the same sites one month after the spill, both for sites impacted by oil and unaffected reference sites. While the availability of pre-spill data made this analysis one of the most powerful to date for testing impacts of oil on shoreline environments, no clear changes attributable to oiling could be identified. Discharged oil appeared to cause very little impact in the intertidal and shallow subtidal zones, with such impacts lying within the range of natural spatial and temporal variation at sites investigated. Factors considered to minimize impact in Galápagos included paucity of fully sheltered shores in spill path, moderate wave action, warm temperature, high levels of sunlight, and mixing of bunker oil with diesel.
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
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
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)
Taylor dispersion of nanoparticles
NASA Astrophysics Data System (ADS)
Balog, Sandor; Urban, Dominic A.; Milosevic, Ana M.; Crippa, Federica; Rothen-Rutishauser, Barbara; Petri-Fink, Alke
2017-08-01
The ability to detect and accurately characterize particles is required by many fields of nanotechnology, including materials science, nanotoxicology, and nanomedicine. Among the most relevant physicochemical properties of nanoparticles, size and the related surface-to-volume ratio are fundamental ones. Taylor dispersion combines three independent phenomena to determine particle size: optical extinction, translational diffusion, and sheer-enhanced dispersion of nanoparticles subjected to a steady laminar flow. The interplay of these defines the apparent size. Considering that particles in fact are never truly uniform nor monodisperse, we rigorously address particle polydispersity and calculate the apparent particle size measured by Taylor dispersion analysis. We conducted case studies addressing aqueous suspensions of model particles and large-scale-produced "industrial" particles of both academic and commercial interest of various core materials and sizes, ranging from 15 to 100 nm. A comparison with particle sizes determined by transmission electron microscopy confirms that our approach is model-independent, non-parametric, and of general validity that provides an accurate account of size polydispersity—independently on the shape of the size distribution and without any assumption required a priori.
Large deviations in Taylor dispersion
NASA Astrophysics Data System (ADS)
Kahlen, Marcel; Engel, Andreas; Van den Broeck, Christian
2017-01-01
We establish a link between the phenomenon of Taylor dispersion and the theory of empirical distributions. Using this connection, we derive, upon applying the theory of large deviations, an alternative and much more precise description of the long-time regime for Taylor dispersion.
Magnetically Induced Rotating Rayleigh-Taylor Instability.
Scase, Matthew M; Baldwin, Kyle A; Hill, Richard J A
2017-03-03
Classical techniques for investigating the Rayleigh-Taylor instability include using compressed gasses(1), rocketry(2) or linear electric motors(3) to reverse the effective direction of gravity, and accelerate the lighter fluid toward the denser fluid. Other authors(e.g.)(4)(,)(5)(,)(6) have separated a gravitationally unstable stratification with a barrier that is removed to initiate the flow. However, the parabolic initial interface in the case of a rotating stratification imposes significant technical difficulties experimentally. We wish to be able to spin-up the stratification into solid-body rotation and only then initiate the flow in order to investigate the effects of rotation upon the Rayleigh-Taylor instability. The approach we have adopted here is to use the magnetic field of a superconducting magnet to manipulate the effective weight of the two liquids to initiate the flow. We create a gravitationally stable two-layer stratification using standard flotation techniques. The upper layer is less dense than the lower layer and so the system is Rayleigh-Taylor stable. This stratification is then spun-up until both layers are in solid-body rotation and a parabolic interface is observed. These experiments use fluids with low magnetic susceptibility, |χ| ~ 10(-6) - 10(-5), compared to a ferrofluids. The dominant effect of the magnetic field applies a body-force to each layer changing the effective weight. The upper layer is weakly paramagnetic while the lower layer is weakly diamagnetic. When the magnetic field is applied, the lower layer is repelled from the magnet while the upper layer is attracted towards the magnet. A Rayleigh-Taylor instability is achieved with application of a high gradient magnetic field. We further observed that increasing the dynamic viscosity of the fluid in each layer, increases the length-scale of the instability.
Incompressible Rayleigh–Taylor Turbulence
NASA Astrophysics Data System (ADS)
Boffetta, Guido; Mazzino, Andrea
2017-01-01
Basic fluid equations are the main ingredient in the development of theories of Rayleigh–Taylor buoyancy-induced instability. Turbulence arises in the late stage of the instability evolution as a result of the proliferation of active scales of motion. Fluctuations are maintained by the unceasing conversion of potential energy into kinetic energy. Although the dynamics of turbulent fluctuations is ruled by the same equations controlling the Rayleigh–Taylor instability, here only phenomenological theories are currently available. The present review provides an overview of the most relevant (and often contrasting) theoretical approaches to Rayleigh–Taylor turbulence together with numerical and experimental evidence for their support. Although the focus is mainly on the classical Boussinesq Rayleigh–Taylor turbulence of miscible fluids, the review extends to other fluid systems with viscoelastic behavior, affected by rotation of the reference frame, and, finally, in the presence of reactions.
ERIC Educational Resources Information Center
Deutelbaum, Wendy
In contrast to a teacher-dominated literature classroom where authority rests with the one who has the power to grade, a classroom dedicated to cultivating the creative process breaks down the traditional hierarchies (such as theory and practice, text and reader, and organization and improvisation) and concentrates on the needs of the individual…
An Attempt to Extend Taylor-Spence Drive Theory to Vocational Choice Behavior
ERIC Educational Resources Information Center
Sharf, Richard S.
1972-01-01
Predictions were made from Taylor-Spence drive theory about vocational choice behavior. Although the results did not specifically support the predictions made from Taylor-Spence theory, they indicated the potential usefulness of certain concepts in this theory and suggested several lines of inquiry for further research. (Author)
An Attempt to Extend Taylor-Spence Drive Theory to Vocational Choice Behavior
ERIC Educational Resources Information Center
Sharf, Richard S.
1972-01-01
Predictions were made from Taylor-Spence drive theory about vocational choice behavior. Although the results did not specifically support the predictions made from Taylor-Spence theory, they indicated the potential usefulness of certain concepts in this theory and suggested several lines of inquiry for further research. (Author)
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.
The Rayleigh-Taylor instability
NASA Astrophysics Data System (ADS)
Piriz, A. R.; Cortázar, O. D.; López Cela, J. J.; Tahir, N. A.
2006-12-01
A new approach to the Rayleigh-Taylor instability is presented that yields exact solutions for the simplest cases and provides approximate but still very accurate analytical expressions for important and more complex cases involving nonideal fluids. The approach is based on Newton's second law and allows for an intuitive and physically appealing explanation of the mechanisms underlying the instability.
The Remainder in Taylor's Formula.
ERIC Educational Resources Information Center
Poffald, Esteban I.
1990-01-01
Presented is a mean-value theorem that generalizes the Taylor-Lagrange formula. Discussed is the asymptotic behavior of the remainder term of the formula. Several numerical schemes are derived to approximate the solution to initial-valued first order differential equations. (KR)
Rotating Rayleigh-Taylor turbulence
NASA Astrophysics Data System (ADS)
Boffetta, G.; Mazzino, A.; Musacchio, S.
2016-09-01
The turbulent Rayleigh-Taylor system in a rotating reference frame is investigated by direct numerical simulations within the Oberbeck-Boussinesq approximation. On the basis of theoretical arguments, supported by our simulations, we show that the Rossby number decreases in time, and therefore the Coriolis force becomes more important as the system evolves and produces many effects on Rayleigh-Taylor turbulence. We find that rotation reduces the intensity of turbulent velocity fluctuations and therefore the growth rate of the temperature mixing layer. Moreover, in the presence of rotation the conversion of potential energy into turbulent kinetic energy is found to be less effective, and the efficiency of the heat transfer is reduced. Finally, during the evolution of the mixing layer we observe the development of a cyclone-anticyclone asymmetry.
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.
Is the magnetopause Rayleigh-Taylor unstable sometimes?
Gratton, F.T.; Farrugia, C.J.; Cowley, S.W.H.
1996-03-01
The authors examine the question of whether the magnetopause is Rayleigh-Taylor stable. The magnetopause tends to be in continuous motion because of the effect of the dyanmic pressure from the solar wind. When there is a sudden drop in solar wind pressure, and the magnetopause tends to accelerate sunward, a situation is created where the magnetopause may go unstable. The authors look at two possible stabilizing effects, first the magnetic shear which exists across the magnetopause, and then the viscous nature of the magnetosheath plasma. They find that large shear leads to stability for the Rayleigh-Taylor mode. When there is a strong northward component in the magnetosheath field, they find that the magnetopause may be unstable to this mode for both global and internal modes. They also discuss the effect of such instabilities on observations.
Exact axisymmetric Taylor states for shaped plasmas
Cerfon, Antoine J. O'Neil, Michael
2014-06-15
We present a general construction for exact analytic Taylor states in axisymmetric toroidal geometries. In this construction, the Taylor equilibria are fully determined by specifying the aspect ratio, elongation, and triangularity of the desired plasma geometry. For equilibria with a magnetic X-point, the location of the X-point must also be specified. The flexibility and simplicity of these solutions make them useful for verifying the accuracy of numerical solvers and for theoretical studies of Taylor states in laboratory experiments.
On Taylor's justification of medical informed consent.
Varelius, Jukka
2012-05-01
In contemporary Western biomedical ethics, informed consent practices are commonly justified in terms of the intrinsic value of patient autonomy. James Stacey Taylor maintains that this conception of the moral grounding of medical informed consent is mistaken. On the basis of his reasoning to that effect, Taylor argues that medical informed consent is justified by the instrumental value of personal autonomy. In this article, I examine whether Taylor's justification of medical informed consent is plausible.
Ionic emission from Taylor cones
NASA Astrophysics Data System (ADS)
Castro Reina, Sergio
Electrified Taylor cones have been seen as an efficient way to generate thrust for space propulsion. Especially the pure ionic regime (PIR) combines a very high specific impulse (thrust per unit mass) and efficiency, which is very important to reduce fuel transportation costs. The PIR has been primarily based on electrosprays of liquid metals [Swatik and Hendricks 1968, Swatik 1969]. However, emissions dominated by or containing exclusively ions have also been observed from nonmetallic purely ionic substances, initially sulfuric acid [Perel et al. 1969], and more recently room temperature molten salts referred to as ionic liquids (ILs) [Romero-Sanz et al. 2003]. The recent use of the liquid metal ion source (LMIS) with ILs, becoming this "new" source to be known as ionic liquid ion source (ILIS) [Lozano and Martinez-Sanchez 2005], has shown important differences on the emission from Taylor cones with the traditional hollow capillary. This new source seems to be more flexible than the capillary [Paulo, Sergio, carlos], although its low emission level (low thrust) is an important drawback from the space propulsion point of view. Throughout the thesis I have studied some aspects of the ionic emission from ionic liquid Taylor cones and the influence of the properties of the liquids and the characteristic of source on the emission. I have unraveled the reason why ILIS emits such low currents (˜200 nA) and found a way to solve this problem increasing the current up to capillary levels (˜1000 nA) [Castro and Fernandez de la Mora 2009]. I have also tried to reduce ion evaporation while reducing the emitted droplet size in order to increase the thrust generated while keeping the efficiency relatively high and I have measured the energy of evaporation of several cations composing ionic liquids, mandatory step to understand ionic evaporation.
Rotating Rayleigh-Taylor instability
NASA Astrophysics Data System (ADS)
Scase, M. M.; Baldwin, K. A.; Hill, R. J. A.
2017-02-01
The effect of rotation upon the classical Rayleigh-Taylor instability is investigated. We consider a two-layer system with an axis of rotation that is perpendicular to the interface between the layers. In general, we find that a wave mode's growth rate may be reduced by rotation. We further show that in some cases, unstable axisymmetric wave modes may be stabilized by rotating the system above a critical rotation rate associated with the mode's wavelength, the Atwood number, and the flow's aspect ratio.
Quasiperiodic Taylor-Couette Flow
NASA Astrophysics Data System (ADS)
Coughlin, Katie
1990-01-01
We present analysis and computations of the transition from wavy vortex flow to modulated wavy (or quasiperiodic) flow in the axially periodic Taylor-Couette system. We derive the correct functional form for quasiperiodic solutions to the Navier-Stokes equations, and show that all the space -time symmetry properties follow directly. The fluid equations are solved numerically using a pseudo-spectral initial value code for a number of wave, modulated wave, and weakly chaotic flows. At high Reynolds number R > 7R_{c}, where R _{c} is the critical value for transition to Taylor vortex flow, our solutions can be compared directly to experimentally observed flows. A simple physical picture is associated with the modulation, which we argue arises as an instability of the vortex outflow jet. Numerical evidence suggests that the transition from modulated waves to chaos in these flows is also associated with an instability of the outflow, and can be described with a low-dimensional model. In addition, we have discovered examples of modulated waves at low Reynolds number. This quasiperiodic flow goes through a period-doubling cascade to chaos, with the modulation period relative to the frame rotating with the first wave doubling as R increases.
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.
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 0...
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, 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...
Spectral stability of Taylor's vortex array
NASA Technical Reports Server (NTRS)
Lin, S. P.; Tobak, M.
1986-01-01
In a global sense it is shown that the two-dimensional Taylor vortex array, an exact solution of the Navier-Stokes equation, is absolutely and monotonically stable with respect to infinitesimal disturbances of all discrete frequencies as long as the viscosity is positive. It is suggested that the Taylor vortex array may also be stable with respect to finite amplitude disturbances.
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…
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…
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…
Spectral stability of Taylor's vortex array
NASA Technical Reports Server (NTRS)
Lin, S. P.; Tobak, M.
1986-01-01
In a global sense it is shown that the two-dimensional Taylor vortex array, an exact solution of the Navier-Stokes equation, is absolutely and monotonically stable with respect to infinitesimal disturbances of all discrete frequencies as long as the viscosity is positive. It is suggested that the Taylor vortex array may also be stable with respect to finite amplitude disturbances.
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, 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, 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, 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...
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...
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.
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.
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.
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
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
Nonideal Rayleigh-Taylor mixing.
Lim, Hyunkyung; Iwerks, Justin; Glimm, James; Sharp, David H
2010-07-20
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.
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.
76 FR 18378 - Amendment of Class E Airspace; Taylor, AZ
Federal Register 2010, 2011, 2012, 2013, 2014
2011-04-04
... Federal Aviation Administration 14 CFR Part 71 Amendment of Class E Airspace; Taylor, AZ AGENCY: Federal... Taylor Airport, Taylor, AZ, to accommodate aircraft using the CAMBO One Departure, and the Area Navigation (RNAV) standard instrument approach procedures at Taylor Airport. This will improve the safety...
Synthetic Division, Taylor Polynomials, Partial Fractions.
ERIC Educational Resources Information Center
Lambert, Howard B.
1989-01-01
Reviews the underpinnings of synthetic division. Shows how to quickly obtain the coefficients of the Taylor expansion of a polynomial about a point, and a partial fraction decomposition of a polynomial. (MVL)
Taylor dispersion analysis of mixtures.
Cottet, Hervé; Biron, Jean-Philippe; Martin, Michel
2007-12-01
Taylor dispersion analysis (TDA) is a fast and simple method for determining hydrodynamic radii. In the case of sample mixtures, TDA, as the other nonseparative methods, leads to an average diffusion coefficient on the different molecules constituting the mixture. We set in this work the equations giving, on a consistent basis, the average values obtained by TDA with detectors with linear response functions. These equations confronted TDA experiments of sample mixtures containing different proportions of a small molecule and a polymer standard. Very good agreement between theory and experiment was obtained. In a second part of this work, on the basis of monomodal or bimodal molar mass distributions of polymers, the different average diffusion coefficients corresponding to TDA were compared to the z-average diffusion coefficient (D(z)) obtained from dynamic light scattering (DLS) experiments and to the weight average diffusion coefficient (D(w)). This latter value is sometimes considered as the most representative of the sample mixture. From these results, it appears that, for monomodal distribution and relatively low polydispersity (I = 1.15), the average diffusion coefficient generally derived from TDA is very close to Dw. However, for highly polydisperse samples (e.g., bimodal polydisperse distributions), important differences could be obtained (up to 35% between TDA and D(w)). In all the cases, the average diffusion coefficient obtained by TDA for a mass concentration detector was closer to the Dw value than the z-average obtained by DLS.
Willmott, G.R.; Radford, D.D.
2005-05-01
The deformation and fracture behavior of soda-lime and borosilicate glass rods was examined during classic and symmetric Taylor impact experiments for impact pressures to 4 and 10 GPa, respectively. High-speed photography and piezoresistive gauges were used to measure the failure front velocities in both glasses, and for impact pressures below {approx}2 GPa the failure front velocity increases rapidly with increasing pressure. As the pressure was increased above {approx}3 GPa, the failure front velocities asymptotically approached maximum values between the longitudinal and shear wave velocities of each material; at {approx}4 GPa, the average failure front velocities were 4.7{+-}0.5 and 4.6{+-}0.5 mm {mu}s{sup -1} for the soda-lime and borosilicate specimens, respectively. The observed mechanism of failure in these experiments involved continuous pressure-dependent nucleation and growth of microcracks behind the incident wave. As the impact pressure was increased, there was a decrease in the time to failure. The density of cracks within the failed region was material dependent, with the more open-structured borosilicate glass showing a larger fracture density.
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.
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
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.
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.
Resistance law for a turbulent Taylor-Couette flow at very large Taylor numbers
NASA Astrophysics Data System (ADS)
Balonishnikov, A. M.
2016-11-01
Based on the semi-empirical model of the transport of the specific rate of turbulence energy dissipation, it has been concluded that the resistance laws are observed for a turbulent Taylor-Couette flow between independently rotating coaxial cylinders for very large Taylor numbers.
Suppressing Taylor vortices in a Taylor-Couette flow system with free surface
NASA Astrophysics Data System (ADS)
Bouabdallah, A.; Oualli, H.; Mekadem, M.; Gad-El-Hak, M.
2016-11-01
Taylor-Couette flows have been extensively investigated due to their many industrial applications, such as catalytic reactors, electrochemistry, photochemistry, biochemistry, and polymerization. Mass transfer applications include extraction, tangential filtration, crystallization, and dialysis. A 3D study is carried out to simulate a Taylor-Couette flow with a rotating and pulsating inner cylinder. We utilize FLUENT to simulate the incompressible flow with a free surface. The study reveals that flow structuring is initiated with the development of an Ekman vortex at low Taylor number, Ta = 0 . 01 . For all encountered flow regimes, the Taylor vortices are systematically inhibited by the pulsatile motion of the inner cylinder. A spectral analysis shows that this pulsatile motion causes a rapid decay of the free surface oscillations, from a periodic wavy movement to a chaotic one, then to a fully turbulent motion. This degenerative free surface behavior is interpreted as the underlying mechanism responsible for the inhibition of the Taylor vortices.
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.
Accelerated Taylor plumes for MIF targets
NASA Astrophysics Data System (ADS)
Brown, M. R.; Schaffner, D. A.; Parks, H. L.; Rock, A. B.
2015-11-01
The SSX plasma device has been converted to a 2.5 m merging plasma wind tunnel configuration. Experiments are underway to study merging and stagnation of high density, helical Taylor states to employ as a potential target for magneto-inertial fusion. Eventually, SSX Taylor states will be accelerated to over 100 km / s and compressed to small volumes either by stagnation or merging. Initial un-accelerated merging studies produce peak proton densities of 5 ×1015cm-3 . Densities are measured with a precision quadrature He-Ne laser interferometer. Typical merged plasma parameters are Ti = 20 eV, Te = 10 eV, B = 0 . 4 T with lifetimes of 100 μs. Results from a single prototype acceleration coil will be presented, as well as initial simulation studies of Taylor state plasma acceleration using multiple staged, pulsed theta-pinch coils. Work supported by DOE ARPA-E ALPHA program.
Test of Taylor's Hypothesis with Distributed Temperature
NASA Astrophysics Data System (ADS)
Cheng, Y.; Gentine, P.; Sayde, C.; Tanner, E.; Ochsner, T. E.; Dong, J.
2016-12-01
Taylor's hypothesis[Taylor, 1938] assumes that mean wind speed carries the spatial pattern of turbulent motion past a fixed point in a "frozen" way, which has been widely used to relate streamwise wavenumber and angular frequency . Experiments[Fisher, 1964; Tong, 1996] have shown some deviation from Taylor's hypothesis at highly turbulent intensity flows and at high wavenumbers. However, the velocity or scalar measurements have always been fixed at a few spatial points rather than distributed in space. This experiment was designed for the first time to directly compare the time and spatial spectrum of temperature to test Taylor's hypothesis, measuring temperature with high resolution in both time and space by Distributed Temperature Sensing utilizing the attenuation difference of Raman scattering in the optic fiber at the MOISST site Oklahoma. The length of transact is 233 meters along the dominant wind direction. The temperature sampling distance is 0.127m and sampling time frequency is 1 Hz. The heights of the 4 fiber cables parallel to ground are 1m, 1.254m, 1.508m and 1.762m respectively. Also, eddy covariance instrument was set up near the Distributed Temperature Sensing as comparison for temperature data. The temperature spatial spectrum could be obtained with one fixed time point, while the temperature time spectrum could be obtained with one fixed spatial point in the middle of transact. The preliminary results would be presented in the AGU fall meeting. Reference Fisher, M. J., and Davies, P.O.A.L (1964), Correlation measurements in a non-frozen pattern of turbulence, Journal of fluid mechanics, 18(1), 97-116. Taylor, G. I. (1938), The spectrum of turbulence, Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences, 164(919), 476-490. Tong, C. (1996), Taylor's Hypothesis and Two-point Coherence Measurements, Boundary-Layer Meteorology, 81(3), 399-410.
Taylorism in a post-modern age?
Freemantle, N
1995-02-01
F.W. Taylor made an early and important contribution to the organisation of work in an industrial society. His ideas, or versions of his ideas, are once again receiving attention. Some commentators even describe a new or neo Taylorism (Pollitt, 1990). This paper argues that the only theoretical justification for the re-introduction of Taylorist strategies in the workplace is found in the notion of the post-modern world; where rationality is replaced by a ritual of signs and work becomes part of that ritual; where form replaces rationale, and strategies for work are governed by processes of survival in the remnants of modernity.
On the Taylor Approximation of Control Systems.
1984-01-01
ABSTRACT Let gi (i - 1 , ... , m) be smooth vector fields on Rd, and let Tn - 1 gi be their Taylor expansions of order n - I at the origin. The system...control systems, Picard iterates, Taylor expansion. Work Unit Number 5 (Optimization and Large Scale Systems) Istituto di Matematica Applicata...control system on Ad: I _~~d x~)= m g(x(t))ou (t), x(o) = O ii 1 Given a control u, in general there exists no explicit formula to exactly compute the
A reflection on Cicely Saunders' views on a good death through the philosophy of Charles Taylor.
Thoresen, Lisbeth
2003-01-01
In her writings, Cicely Saunders has developed a total framework of caring for seriously ill people. Saunders' reaction to what she has experienced as bad contemporary post-war health care is to be found in her hospice philosophy. In this article this philosophy is analysed through the writings of Charles Taylor. Taylor is a Canadian philosopher who has delivered important views on what it means to live a 'good' and 'authentic' life in a modern society. By focusing on Saunders' writings from Taylor's perspective it becomes apparent that Saunders has created a very modern theory. The author has found that different aspects of a good and authentic life are important values in Saunders' good and authentic death. These findings are followed by one question: is Saunders' hospice philosophy too focused on values such as individuality, control and autonomy, giving too little attention to fragility and dependency?
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
Rayleigh-Taylor instability in soft elastic layers.
Riccobelli, D; Ciarletta, P
2017-05-13
This work investigates the morphological stability of a soft body composed of two heavy elastic layers attached to a rigid surface and subjected only to the bulk gravity force. Using theoretical and computational tools, we characterize the selection of different patterns as well as their nonlinear evolution, unveiling the interplay between elastic and geometric effects for their formation. Unlike similar gravity-induced shape transitions in fluids, such as the Rayleigh-Taylor instability, we prove that the nonlinear elastic effects saturate the dynamic instability of the bifurcated solutions, displaying a rich morphological diagram where both digitations and stable wrinkling can emerge. The results of this work provide important guidelines for the design of novel soft systems with tunable shapes, with several applications in engineering sciences.This article is part of the themed issue 'Patterning through instabilities in complex media: theory and applications.' © 2017 The Author(s).
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.
CURTIS TAYLOR, PRESIDENT OF LINC RESEARCH CORP.
2016-04-27
CURTIS O. TAYLOR, PRESIDENT OF LINC RESEARCH CORP, (L), AND JEFF LINDNER, CHIEF ENGINEER, POSE WITH HARDWARE FOR THEIR PATENTED TECHNOLOGY, FLUID STRUCTURE COUPLING, WHICH USES SIMPLE PHYSICS TO DAMPEN POTENTIALLY HARMFUL SHAKING IN STRUCTURES. INSTALLATION OF THE FLUID STRUCTURE COUPLING TECHNOLOGY IN A BUILDING WILL TAKE PLACE IN SUMMER OF 2016.
Modelling VLSI circuits using Taylor series
NASA Astrophysics Data System (ADS)
Kocina, Filip; Nečasová, Gabriela; Veigend, Petr; Chaloupka, Jan; Šátek, Václav; Kunovský, Jiří
2017-07-01
The paper introduces the capacitor substitution for CMOS logic gates, i.e. NANDs, NORs and inverters. It reveals the necessity of a very accurate and fast method for solving this problem. Therefore the Modern Taylor Series Method (MTSM) is used which provides an automatic choice of a higher order during the computation and a larger integration step size while keeping desired accuracy.
Characterization of Taylor plumes on SSX
NASA Astrophysics Data System (ADS)
Brown, M. R.; Kaur, M.; Han, J.; Shrock, J. E.; Schaffner, D. A.
2016-10-01
We have added a 1 m glass extension to the SSX plasma wind tunnel device. Initial experiments have been performed to characterize velocity, density, and magnetic field of relaxed helical Taylor states formed in the glass boundary. We are also experimenting with resistive and mesh liners to provide some flux conservation of the Taylor states. Under construction is a theta pinch coil and pulsed power supply to accelerate the fully relaxed (tilted) Taylor states. Once characterization studies are complete, one or two prototype theta pinch coils will be used to accelerate the Taylor states to over 100 km / s and compressed to small volumes by stagnation. A segmented resistive or mesh flux conserver may also be employed. Preliminary un-accelerated characterizaton studies produce peak proton densities of 1015cm-3 . Densities are measured with a precision quadrature He-Ne laser interferometer located in an expansion volume downstream of the glass extension. Temperatures will be measured by an ion Doppler spectrometer. Stagnated plasma parameters will be ne 1016cm-3 with Ti >= 20eV , B >= 0.5 T with lifetimes over 100 μs . Results from a single prototype acceleration coil will be presented. Work supported by DOE ARPA-E ALPHA program.
Tree ecophysiology research at Taylor Woods
Thomas E. Kolb; Nate G. McDowell
2008-01-01
We summarize the key findings of tree ecophysiology studies performed at Taylor Woods, Fort Valley Experimental Forest, Arizona between 1994 and 2003 that provide unique insight on impacts of long-term stand density management in ponderosa pine forests on tree water relations, leaf gas exchange, radial growth, leaf area-to-sapwood-area ratio, growth efficiency, leaf...
Biographical Note--Robert S. Taylor.
ERIC Educational Resources Information Center
Van der Veer Martens, Betsy
1999-01-01
In an age of specialists, Robert Saxon Taylor has been one of the great generalists in the theory and practice of information transfer and use. This sidebar discusses his seminal scholarly contributions, influence on students and senior colleagues alike, memberships and chairmanships, tenure as dean (1972-1981) and professor at what became the…
Nonlinear stability of Taylor's vortex array
NASA Technical Reports Server (NTRS)
Lin, S. P.; Tobak, M.
1987-01-01
It is proved that the two-dimensional Taylor vortex array, which is an exact unsteady solution of the Navier-Stokes equation, is globally and asymptotically stable in the mean with respect to three-dimensional periodic disturbances. A time-dependent bound on the decay rate of the kinetic energy of disturbances is obtained.
Application of Taylor's series to trajectory propagation
NASA Technical Reports Server (NTRS)
Stanford, R. H.; Berryman, K. W.; Breckheimer, P. J.
1986-01-01
This paper describes the propagation of trajectories by the application of the preprocessor ATOMCC which uses Taylor's series to solve initial value problems in ordinary differential equations. Comparison of the results obtained with those from other methods are presented. The current studies indicate that the ATOMCC preprocessor is an easy, yet fast and accurate method for generating trajectories.
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…
Cusp formation in drops inside Taylor cones
NASA Astrophysics Data System (ADS)
Marin, Alvaro G.; Loscertales, Ignacio G.; Barrero, Antonio
2005-11-01
Here, we report the formation of cusp in insulating drops inside compound Taylor cones. The action of the electrical shear stress acting on the outer interface, which is transmitted by viscous forces inside the Taylor cone, tends to deform the drop of insulating liquid placed inside. For appropriate values of the capillary number, the insulating drop develops a steady cusp angle which depends on both the capillary number and the conducting to insulating viscosity ratio. A self-similar analysis has been developed to qualitatively describe the flow inside these compounds Taylor cones. Any perturbation of the cusp gives rise to an intermittent emission of tiny droplets; this effect may recall the tip-streaming observed by G.I. Taylor in his four-roll mill device. This emission can be stabilized by an appropriate control of the injected flow rate of the insulating liquid. When the capillary number increases, the cusped interface turns into a spout which flows coated by the conducting liquid forming the electrified coaxial jet which has been successfully employed for the production of nanocapsules, coaxial nanofibers and nanotubes (Science 295, n. 5560, 1695, 2002; JACS 126, 5376, 2004).
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…
Nonlinear stability of Taylor's vortex array
NASA Technical Reports Server (NTRS)
Lin, S. P.; Tobak, M.
1987-01-01
It is proved that the two-dimensional Taylor vortex array, which is an exact unsteady solution of the Navier-Stokes equation, is globally and asymptotically stable in the mean with respect to three-dimensional periodic disturbances. A time-dependent bound on the decay rate of the kinetic energy of disturbances is obtained.
Application of Taylor's series to trajectory propagation
NASA Technical Reports Server (NTRS)
Stanford, R. H.; Berryman, K. W.; Breckheimer, P. J.
1986-01-01
This paper describes the propagation of trajectories by the application of the preprocessor ATOMCC which uses Taylor's series to solve initial value problems in ordinary differential equations. Comparison of the results obtained with those from other methods are presented. The current studies indicate that the ATOMCC preprocessor is an easy, yet fast and accurate method for generating trajectories.
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,…
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,…
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.
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.
Stability of compressible Taylor-Couette flow
NASA Technical Reports Server (NTRS)
Kao, Kai-Hsiung; Chow, Chuen-Yen
1991-01-01
Compressible stability equations are solved using the spectral collocation method in an attempt to study the effects of temperature difference and compressibility on the stability of Taylor-Couette flow. It is found that the Chebyshev collocation spectral method yields highly accurate results using fewer grid points for solving stability problems. Comparisons are made between the result obtained by assuming small Mach number with a uniform temperature distribution and that based on fully incompressible analysis.
Stability of compressible Taylor-Couette flow
NASA Technical Reports Server (NTRS)
Kao, Kai-Hsiung; Chow, Chuen-Yen
1991-01-01
Compressible stability equations are solved using the spectral collocation method in an attempt to study the effects of temperature difference and compressibility on the stability of Taylor-Couette flow. It is found that the Chebyshev collocation spectral method yields highly accurate results using fewer grid points for solving stability problems. Comparisons are made between the result obtained by assuming small Mach number with a uniform temperature distribution and that based on fully incompressible analysis.
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.
Fisheries Aspects of Seamounts and Taylor Columns
1986-09-01
NAVAL POSTGRADUATE SCHOOL DTI I V4 D THESIS FISH ERIES ASPECT S OF SEAMOUNTS AND) TAYLOR COLUMNS by Russell E. Brainard September 1986 Thesis Co...Takahashi and Sasaki, 1977; Genin and Boehlert, 1985). In fact, many seamounts are now known to be excellent fishing grounds for both pelagic nekton, such as...Pentaceros richardsoni and alfonsin, Baryx splendeus on the southern Emperor-northern Hawaiian Ridge seamounts. Both of these rare fish are eagerly
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.
Deformity correction in Haiti with the Taylor Spatial Frame.
Alexis, Francel; Herzenberg, John E; Nelson, Scott C
2015-01-01
The Taylor Spatial Frame (TSF) is an external-fixator that corrects deformities in 6 axes, and can successfully manage disorders involving multiplanar deformities. In the developing-world, orthopaedic surgeons are often faced with deformities from neglected trauma and birth defects more severe than those typically seen in developed-countries. This article evaluates the applicability of TSF in the challenging medical environment of Haiti. At Haiti Adventist Hospital, the authors treated 80 cases using the TSF with a minimum follow-up of 1-year. Good results were observed in 99% of the cases (79 out of 80), approaching similar outcomes than those described in literature. Copyright © 2015 Elsevier Inc. All rights reserved.
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
Particle shear-rate history in a Taylor-Couette column
Rudman, M.; Thompson, M.C.; Hourigan, K.
1994-12-31
In previous investigations of shear-rate influence on aggregation processes in Taylor-Couette columns, average shear rates have been determined which were based on either laminar non-vortex flow solutions or numerical solutions of Taylor Vortex flow. correlations between effectiveness of aggregation and shear rate are then made on the basis of this average shear rate. In this study the authors show that the use of this approach must be undertaken with caution. Particle tracking algorithms are coupled with a numerical solution of the fluid flow field to obtain shear histories for several particle densities. It is shown that an average fluid shear rate is not necessarily correlated to the average shear rate to which aggregating particles are subject as they traverse the Taylor-Couette column. It is observed that as the rotation rate (or the non-dimensional parameter known as the Taylor number) is increased beyond the maximum allowed for Couette flow, the percentage of neutrally buoyant particles exposed at some time during their history to large shear rates increases. This point is even more important when buoyant particles are considered.
Inward propagating chemical waves in Taylor vortices.
Thompson, Barnaby W; Novak, Jan; Wilson, Mark C T; Britton, Melanie M; Taylor, Annette F
2010-04-01
Advection-reaction-diffusion (ARD) waves in the Belousov-Zhabotinsky reaction in steady Taylor-Couette vortices have been visualized using magnetic-resonance imaging and simulated using an adapted Oregonator model. We show how propagating wave behavior depends on the ratio of advective, chemical and diffusive time scales. In simulations, inward propagating spiral flamelets are observed at high Damköhler number (Da). At low Da, the reaction distributes itself over several vortices and then propagates inwards as contracting ring pulses--also observed experimentally.
Predictability of Rayleigh-Taylor instability
Viecelli, J.A.
1986-03-27
Numerical experiments modeling the Rayleigh Taylor instability are carried out using a two-dimensional incompressible Eulerian hydrodynamic code VFTS. The method of integrating the Navier-Stokes equations including the viscous terms is similar to that described in Kim and Moin, except that Lagrange particles have been added and provision for body forces is given. The Eulerian method is 2nd order accurate in both space and time, and the Poisson equation for the effective pressure field is solved exactly at each time step using a cyclic reduction method. 3 refs., 3 figs.
Curvature suppresses the Rayleigh-Taylor instability
Trinh, Philippe H.; Kim, Hyoungsoo; Hammoud, Naima; Howell, Peter D.; Chapman, S. Jonathan; Stone, Howard A.
2014-05-01
The dynamics of a thin liquid #12;lm on the underside of a curved cylindrical substrate is studied. The evolution of the liquid layer is investigated as the #12;lm thickness and the radius of curvature of the substrate are varied. A dimensionless parameter (a modi#12;ed Bond number) that incorporates both geometric parameters, gravity, and surface tension is identified, and allows the observations to be classified according to three different flow regimes: stable films, films with transient growth of perturbations followed by decay, and unstable films. Experiments and theory confirm that, below a critical value of the Bond number, curvature of the substrate suppresses the Rayleigh-Taylor instability.
Inward propagating chemical waves in Taylor vortices
NASA Astrophysics Data System (ADS)
Thompson, Barnaby W.; Novak, Jan; Wilson, Mark C. T.; Britton, Melanie M.; Taylor, Annette F.
2010-04-01
Advection-reaction-diffusion (ARD) waves in the Belousov-Zhabotinsky reaction in steady Taylor-Couette vortices have been visualized using magnetic-resonance imaging and simulated using an adapted Oregonator model. We show how propagating wave behavior depends on the ratio of advective, chemical and diffusive time scales. In simulations, inward propagating spiral flamelets are observed at high Damköhler number (Da). At low Da, the reaction distributes itself over several vortices and then propagates inwards as contracting ring pulses—also observed experimentally.
NASA Astrophysics Data System (ADS)
Deguchi, K.; Altmeyer, S.
2013-04-01
Interactions between nearly bicritical modes in Taylor-Couette flow, which have been concerned with the framework of weakly nonlinear theory, are extended to fully nonlinear Navier-Stokes computation. For this purpose, a standard Newton solver for axially periodic flows is generalized to compute any mixed solutions having up to two phases, which typically arise from interactions of two spiral or Taylor vortex modes. Also, a simple theory is developed in order to classify the mixed solutions. With these methods, we elucidate pattern formation phenomena, which have been observed in a Taylor-Couette flow experiment. Focusing on the counter-rotating parameter range, all possible classes of interaction of various solutions with different azimuthal and axial wave numbers are considered within our computational restriction, and we observe numerous connection branches, e.g., footbridge solutions. Some of the mixed solutions result in a three-dimensional wavy spiral solution with axial relative periodicity or an axially doubly periodic toroidally closed vortex solution. The possible connection of the former solution family to spiral turbulence, which has been observed in highly counter-rotating Taylor-Couette flow, is discussed.
Deguchi, K; Altmeyer, S
2013-04-01
Interactions between nearly bicritical modes in Taylor-Couette flow, which have been concerned with the framework of weakly nonlinear theory, are extended to fully nonlinear Navier-Stokes computation. For this purpose, a standard Newton solver for axially periodic flows is generalized to compute any mixed solutions having up to two phases, which typically arise from interactions of two spiral or Taylor vortex modes. Also, a simple theory is developed in order to classify the mixed solutions. With these methods, we elucidate pattern formation phenomena, which have been observed in a Taylor-Couette flow experiment. Focusing on the counter-rotating parameter range, all possible classes of interaction of various solutions with different azimuthal and axial wave numbers are considered within our computational restriction, and we observe numerous connection branches, e.g., footbridge solutions. Some of the mixed solutions result in a three-dimensional wavy spiral solution with axial relative periodicity or an axially doubly periodic toroidally closed vortex solution. The possible connection of the former solution family to spiral turbulence, which has been observed in highly counter-rotating Taylor-Couette flow, is discussed.
Federal Register 2010, 2011, 2012, 2013, 2014
2011-12-08
... Exploratory Drilling AGENCY: Forest Service, USDA. ACTION: Notice of intent to prepare an environmental impact... drilling on the Cibola National Forest, Mount Taylor Ranger District. There are two areas identified for... vicinity of the town of San Mateo. In total, there are up to 279 drill holes that would be drilled over...
76 FR 3570 - Proposed Amendment of Class E Airspace; Taylor, AZ
Federal Register 2010, 2011, 2012, 2013, 2014
2011-01-20
...This action proposes to modify Class E airspace at Taylor Airport, Taylor, AZ. Controlled airspace is necessary to accommodate aircraft using the CAMBO One Departure Area Navigation (RNAV) out of Taylor Airport. The FAA is proposing this action to enhance the safety and management of aircraft operations at Taylor Airport, Taylor, AZ.
Energy transfer in Rayleigh-Taylor instability.
Cook, Andrew W; Zhou, Ye
2002-08-01
The spatial structure and energy budget for Rayleigh-Taylor instability are examined using results from a 512 x 512 x 2040 point direct numerical simulation. The outer-scale Reynolds number of the flow follows a rough t(3) power law and reaches a final value of about 5500. Taylor microscales and Reynolds numbers are plotted to characterize anisotropy in the flow and document progress towards the mixing transition. A mixing parameter is defined which characterizes the relative rates of entrainment and mixing in the flow. The spectrum of each term in the kinetic energy equation is plotted, at regular time intervals, as a function of the inhomogeneous direction and the two-dimensional wave number for the homogeneous directions. The energy spectrum manifests the beginning of an inertial range by the latter stages of the simulation. The production and dissipation spectra become increasingly opposite and separate in wave space as the flow evolves. The transfer spectrum depends strongly on the inhomogeneous direction, with the net transfer being from large to small scales. Energy transfer at the bubble/spike fronts is strictly positive. Extensive cancellation occurs between the pressure and advection terms. The dilatation term produces negligible energy transfer, but its overall effect is to move energy from high to low density regions.
Dynamic Fracture Studies using Sleeved Taylor Specimens
NASA Astrophysics Data System (ADS)
Gilmore, Martin; Foster, Joseph, Jr.; Wilson, Leonard L.; Cullis, Ian
2001-06-01
The characterization of the inelastic response of materials to high rates of loading is a challenging engineering problem. As the load rate increases, the interpretation of the data recovered from the experiment become more difficult. At very high rates of loading, even the inertia of the test specimen must be accounted for in the interpretation of the data. The Taylor impact experiment is specifically designed to exploit the inertia of the specimen to produce very high loading rates and has been used to study the high strain (50materials for many years. Many high-rate loading problems produce failure in the material. This paper addresses the use of the Taylor impact experiment to study these failures. Continuum codes have been used to design sleeved impact specimens to study the failure of materials under high rates of loading. Ductile core materials are used as drivers to control rupture of more brittle sleeves of the material of interest. Annealed copper cores are used to drive dynamic failure a selection of steels. High rate plastic deformation data is presented for the driver and the sleeve together with the fracture data.
A Taylor vortex analogy in granular flows.
Conway, Stephen L; Shinbrot, Troy; Glasser, Benjamin J
2004-09-23
Fluids sheared between concentric rotating cylinders undergo a series of three-dimensional instabilities. Since Taylor's archetypal 1923 study, these have proved pivotal to understanding how fluid flows become unstable and eventually undergo transitions to chaotic or turbulent states. In contrast, predicting the dynamics of granular systems--from nano-sized particles to debris flows--is far less reliable. Under shear these materials resemble fluids, but solid-like responses, non-equilibrium structures and segregation patterns develop unexpectedly. As a result, the analysis of geophysical events and the performance of largely empirical particle technologies might suffer. Here, using gas fluidization to overcome jamming, we show experimentally that granular materials develop vortices consistent with the primary Taylor instability in fluids. However, the vortices observed in our fluidized granular bed are unlike those in fluids in that they are accompanied by novel mixing-segregation transitions. The vortices seem to alleviate increased strain by spawning new vortices, directly modifying the scale of kinetic interactions. Our observations provide insights into the mechanisms of shear transmission by particles and their consequent convective mixing.
A cosmological Slavnov-Taylor identity
Collins, Hael; Holman, R.; Vardanyan, Tereza E-mail: rh4a@andrew.cmu.edu
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.
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
DSM-5 and ADHD - an interview with Eric Taylor.
Taylor, Eric
2013-09-12
In this podcast we talk to Prof Eric Taylor about the changes to the diagnosis of Attention Deficit Hyperactivity Disorder (ADHD) in DSM-5 and how these changes will affect clinical practice. The podcast for this interview is available at: http://www.biomedcentral.com/sites/2999/download/Taylor.mp3.
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…
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…
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...
16. TURNTABLE RECONSTRUCTION BAY & TAYLOR: Photocopy of January ...
16. TURNTABLE RECONSTRUCTION - BAY & TAYLOR: Photocopy of January 1941 photograph taken during reconstruction of the Bay and Taylor turntable. View to northwest taken two days after CA-12-22. Reconstruction work is nearly complete in this view. - San Francisco Cable Railway, Washington & Mason Streets, San Francisco, San Francisco County, CA
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…
Taylor series expansion and modified extended Prony analysis for localization
Mosher, J.C.; Lewis, P.S.
1994-12-01
In the multiple source localization problem, many inverse routines use a rooting of a polynomial to determine the source locations. The authors present a rooting algorithm for locating an unknown number of three-dimensional, near-field, static sources from measurements at an arbitrarily spaced three-dimensional array. Since the sources are near-field and static, the spatial covariance matrix is always rank one, and spatial smoothing approaches are inappropriate due to the spatial diversity. The authors approach the solution through spherical harmonics, essentially replacing the point source function with its Taylor series expansion. They then perform a modified extended Prony analysis of the expansion coefficients to determine the number and location of the sources. The full inverse method is typically ill-conditioned, but a portion of the algorithm is suitable for synthesis analysis. They present a simulation for simplifying point charges limited to a spherical region, using an array of voltage potential measurements made outside the region. Future efforts of this work will focus on adapting the analysis to the electroencephalography and magnetoencephalography.
String-theoretic deformation of the Parke-Taylor factor
NASA Astrophysics Data System (ADS)
Mizera, Sebastian; Zhang, Guojun
2017-09-01
Scattering amplitudes in a range of quantum field theories can be computed using the Cachazo-He-Yuan (CHY) formalism. In theories with color ordering, the key ingredient is the so-called Parke-Taylor factor. In this paper we give a fully SL (2 ,C )-covariant definition and study the properties of a new integrand called the "string Parke-Taylor" factor. It has an α' expansion whose leading coefficient is the field-theoretic Parke-Taylor factor. Its main application is that it leads to a CHY formulation of open string tree-level amplitudes. In fact, the definition of the string Parke-Taylor factor was motivated by trying to extend the compact formula for the first α' correction found by He and Zhang, while the main ingredient in its definition is a determinant of a matrix introduced in the context of string theory by Stieberger and Taylor.
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)
Mixing of two fluids streams in a microchannel using the Taylor-Aris dispersion effect
NASA Astrophysics Data System (ADS)
Wang, Hengzi; Iovenitti, Pio; Harvey, Erol C.; Masood, Syed
2002-11-01
Taylor-Aris dispersion is an unwanted effect in some applications, such as chromatography, because of its rapid dispersion along channel axis direction to cause the difficulties to separation. However, this effect can be used in solving mixing problems. In this presentation, the authors studied mixing of two streams of food dye solution in a microchannel. The two liquids sandwiched in the axis direction, and due to non-slip boundary condition, the slugs of liquids stretched and thus increase their interfacial area. This phenomena was firstly studied by Taylor about the dispersion of solute in a circular capillary, and then improved by Aris. Numerical analysis was applied to design mixing section in microchannels, and simplified experiments were conducted to illustrate the concept.
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)
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)
Rayleigh-Taylor instability in elastic solids
NASA Astrophysics Data System (ADS)
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.
Reverse Taylor Tests on Ultrafine Grained Copper
Mishra, A.; Meyers, M. A.; Martin, M.; Thadhani, N. N.; Gregori, F.; Asaro, R. J.
2006-07-28
Reverse Taylor impact tests have been carried out on ultrafine grained copper processed by Equal Channel Angular Pressing (ECAP). Tests were conducted on an as-received OFHC Cu rod and specimens that had undergone sequential ECAP passes (2 and 8). The average grain size ranged from 30 {mu}m for the initial sample to less than 0.5 {mu}m for the 8-pass samples. The dynamic deformation states of the samples, captured by high speed digital photography were compared with computer simulations run in AUTODYN-2D using the Johnson-Cook constitutive equation with constants obtained from stress-strain data and by fitting to an experimentally measured free surface velocity trace. The constitutive response of copper of varying grain sizes was obtained through quasistatic and dynamic mechanical tests and incorporation into constitutive models.
NASA Astrophysics Data System (ADS)
Braginsky, Stanislav I.; Roberts, Paul H.
This is a sequel to an earlier paper [Roberts, Geophys. Astrophys. Fluid Dynam. v. 49, p. 143 (1989)] in which one of us claimed, on the basis of two sequences of integrations of a particular intermediate model of the geodynamo, that, as the dynamo number increases, a smooth transition occurs from Taylor-like behavior to model-Z-type behavior. A more complete survey of parameter space for this model is presented here which tends to corroborate this conclusion. Also, the relationship provided by this model between the external dipole moment of the field and the heat flux from the core is examined. The asymptotic dependence of solutions in the large dynamo number limit is considered.
New Trends in Taylor Series Based Computations
NASA Astrophysics Data System (ADS)
Kunovský, Jiří; Kraus, Michal; Šátek, Václav
2009-09-01
Motto: For the derivatives of all decent functions analytic formulas can be found but with integration this is only true for very special decent functions. The aim of our paper is to describe a new modern numerical method based on the Taylor Series Method and to show how to evaluate the high accuracy and speed of the corresponding computations. It is also the aim of our paper to show how to calculate finite integrals that are the fundamental part in signal processing, especially in Fourier analysis and how to use it for symbolic operations. It is a fact that the accuracy and stability of the algorithms we have designed significantly exceeds the presently known systems. In particular, the paper wants to concentrate, using the previous results and latest development trends, on the simulation of dynamic systems and on extremely exact mathematical computations.
Curvature suppresses the Rayleigh-Taylor instability
Trinh, Philippe H.; Kim, Hyoungsoo; Hammoud, Naima; ...
2014-05-20
We studied the dynamics of a thin liquid film on the underside of a curved cylindrical substrate. The evolution of the liquid layer is investigated as the film thickness and the radius of curvature of the substrate are varied. A dimensionless parameter (a modified Bond number) that incorporates both geometric parameters, gravity, and surface tension is identified, and allows the observations to be classified according to three different flow regimes: stable films, films with transient growth of perturbations followed by decay, and unstable films. We found that the experiments and theory confirm that, below a critical value of the Bondmore » number, curvature of the substrate suppresses the Rayleigh-Taylor instability.« less
Dynamo transition under Taylor-Green forcing
NASA Astrophysics Data System (ADS)
Yadav, R.; Chandra, M.; Verma, M. K.; Paul, S.; Wahi, P.
2010-09-01
We perform pseudo-spectral simulations of the Taylor-Green dynamo for magnetic Prandtl number of one and produce a bifurcation diagram near the dynamo transition. We observe that the primary dynamo transition is through a supercritical pitchfork bifurcation. We show that the planar magnetic structures near the dynamo transition are due to the emergence of the B(0, 0, 1) and B(0, 0, 2) magnetic Fourier modes, which are born as a result of triadic interactions. Near the transition, the kinetic energy (Eu) and the magnetic energy (Eb) grow linearly with the forcing amplitude F0 with the same slope. The ratio Eb/Eu for F0=[0, 40] ranges from 0 to 3. Beyond the transition, the numerical simulations reveal complex dynamo states with windows of constant, periodic, quasiperiodic, and chaotic magnetic field configurations.
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.
Small Atwood number Rayleigh-Taylor experiments.
Andrews, Malcolm J; Dalziel, Stuart B
2010-04-13
Consideration is given to small Atwood number (non-dimensional density difference) experiments to investigate mixing driven by Rayleigh-Taylor (R-T) instability. The past 20 years have seen the development of novel experiments to investigate R-T mixing and, simultaneously, the advent of high-fidelity diagnostics. Indeed, the developments of experiments and diagnostics have gone hand in hand, and as a result modern R-T experiments rival the capabilities and research scope of shear-driven mixing experiments. Thus, research into the small Atwood number limit has made significant progress over the past 20 years, and has offered important insights into natural mixing processes as well as the general R-T problem. This review of small Atwood number experiments serves as an opportunity to discuss progress, and also to provoke thoughts about future high Atwood number designs and difficulties.
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.
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.
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.
Univariate approximate integration via nested Taylor multivariate function decomposition
NASA Astrophysics Data System (ADS)
Gürvit, Ercan; Baykara, N. A.
2014-12-01
This work is based on the idea of nesting one or more Taylor decompositions in the remainder term of a Taylor decomposition of a function. This provides us with a better approximation quality to the original function. In addition to this basic idea each side of the Taylor decomposition is integrated and the limits of integrations are arranged in such a way to obtain a universal [0;1] interval without losing from the generality. Thus a univariate approximate integration technique is formed at the cost of getting multivariance in the remainder term. Moreover the remainder term expressed as an integral permits us to apply Fluctuationlessness theorem to it and obtain better results.
Correction of deformities in children using the Taylor spatial frame.
Eidelman, Mark; Bialik, Viktor; Katzman, Alexander
2006-11-01
The Taylor spatial frame is a unique external fixator. Despite its growing popularity, few reports on its use have been published. We evaluated the effectiveness of the Taylor spatial frame in the treatment of various deformities in 31 children and adolescents. All but one patient were anatomically corrected. Complications included superficial pin tract infection (45%), three fractures of the femoral regenerate, transient peroneal palsy, and injury to the genicular artery. Despite many challenging problems, our results compared favorably with the results achieved by others. We believe that the Taylor spatial frame is a very capable and accurate fixator for the precise correction of complex deformities.
Taylor dispersion of colloidal particles in narrow channels
NASA Astrophysics Data System (ADS)
Sané, Jimaan; Padding, Johan T.; Louis, Ard A.
2015-09-01
We use a mesoscopic particle-based simulation technique to study the classic convection-diffusion problem of Taylor dispersion for colloidal discs in confined flow. When the disc diameter becomes non-negligible compared to the diameter of the pipe, there are important corrections to the original Taylor picture. For example, the colloids can flow more rapidly than the underlying fluid, and their Taylor dispersion coefficient is decreased. For narrow pipes, there are also further hydrodynamic wall effects. The long-time tails in the velocity autocorrelation functions are altered by the Poiseuille flow.
Taylor Expansion Method for Paleosecular Variation
NASA Astrophysics Data System (ADS)
Kono, M.
2004-12-01
Constable and Parker (1988) first suggested that auss coefficients can be treated as independent normal random variables with variances depending only on the degree. Kono et al. (2000) and Kono and Roberts (2002) demonstrated that this postulate is well satisfied in the long time behavior of various numerical dynamo models. However, significant deviations from the original model of Constable and Parker were also found by the analysis of the paleomagnetic data of the last 5 Ma; most notably the large amplitude in the fluctuation of the (2,1) harmonic. In order to express these facts better, Kono and Tanaka (1995) developed Taylor expansion method. But its performance was not satisfactory enough because the approximation used in the calculation was only up to the second order. This paper presents the Taylor expansion method extended to arbitrarily high approximation. We assume that the long term behavior of the geomagnetic field can be modeled as the sum of two parts; the mean field and the fluctuation m=μ +Δ m, where all the elements of Δ m, mj, are zero-mean normal variates with the variance σ j2. The mean value of a nonlinear quantity can be obtained by averaging the Taylor series about the mean model, with summation rules such as E[Δ mjΔ mk] = σ j2δ jk, etc. Summation of the series to high orders is made possible because the nonlinear quantities (or their first derivatives with respect to a Gauss coefficient) used in paleomagnetism (inclination I, declination D, virtual geomagnetic pole (VGP) position θ p, φ p, etc.) can be expressed as the product of the linear quantities and nonlinear quantities such as the total intensity F. These nonlinear quantities can always be expressed as the square root of the sum of squared linear quantities (e.g., F = √ {X2+Y^2+Z^2}). Because of this property, the general form of the derivatives of nonlinear quantities can be written down in a form that is convenient for calculation using the computers. The assumption of
31 CFR 593.508 - Authorization of emergency medical services.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 31 Money and Finance:Treasury 3 2013-07-01 2013-07-01 false Authorization of emergency medical services. 593.508 Section 593.508 Money and Finance: Treasury Regulations Relating to Money and Finance... TAYLOR SANCTIONS REGULATIONS Licenses, Authorizations and Statements of Licensing Policy §...
31 CFR 593.508 - Authorization of emergency medical services.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 31 Money and Finance:Treasury 3 2014-07-01 2014-07-01 false Authorization of emergency medical services. 593.508 Section 593.508 Money and Finance: Treasury Regulations Relating to Money and Finance... TAYLOR SANCTIONS REGULATIONS Licenses, Authorizations and Statements of Licensing Policy §...
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.
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…
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…
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...
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.
The Spirit and Action of Citizenship: Alex Taylor Community School.
ERIC Educational Resources Information Center
Haggerson, Nelson L.; And Others
1987-01-01
Describes a study of the prosocial atmosphere and citizenship spirit found at Alex Taylor Community School in Edmonton, Canada. Includes a brief background of the project and a description of several motivating citizenship activities within the school. (BSR)
Mixing in Rayleigh-Taylor Instabilities
NASA Astrophysics Data System (ADS)
Calder, A. C.; Fryxell, B.; Rosner, R.; Dursi, L. J.; Olson, K.; Ricker, P. M.; Timmes, F. X.; Zingale, M.; Tufo, H. M.; MacNeice, P.
2000-12-01
Fluid instabilities and subsequent mixing can play a fundamental role in many astrophysical processes, including the shock of a core-collapse supernova propagating through the outer layers of a massive star and the propagation of a burning front through a white dwarf in a thermonuclear runaway supernova. We present direct numerical simulations of mixing at Rayleigh-Taylor unstable interfaces performed with the Flash code, developed at the ASCI/Alliances Center for Astrophysical Thermonuclear Flashes at the University of Chicago. We present results of both single- and multi-mode studies in 2- and 3-dimensions. Our results indicate that 3-d perturbations grow significantly faster than 2-d perturbations and that grid resolution can have a significant effect on instability growth rates. We also find that unphysical diffusive mixing occurs at the fluid interface, particularly in poorly resolved simulations, making it difficult to maintain the purity of our fluids. This work was supported by the U.S Department of Energy under grant No. B341495.
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.
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. (c) 2016 APA, all rights reserved).
Dynamic Fracture Studies Using Sleeved Taylor Specimens
NASA Astrophysics Data System (ADS)
Gilmore, Martin R.; Foster, Joseph C., Jr; Wilson, Leo L.
2002-07-01
The characterization of the inelastic response of materials to high rates of loading is a challenging engineering problem. As the load rate increases, the interpretation of the data recovered from the experiment become more difficult. At very high rates of loading, even the inertia of the test specimen must be accounted for in the interpretation of the data 1. The Taylor impact experiment is specifically designed to exploit the inertia of the specimen to produce very high loading rates and has been used to study the high strain (50%), high strain rate (103-4) behavior of materials for many years 2. Many high-rate loading problems produce failure in the material. Continuum codes have been used to design sleeved impact specimens to study the failure of materials under high rates of loading. Ductile core materials are used as drivers to control rupture of more brittle sleeves of the material of interest. Annealed copper cores are used to drive dynamic failure in AF1410 steel. High rate plastic deformation data are presented for the driver and the sleeve together with the fracture data.
Rayleigh-Taylor instability simulations with CRASH
NASA Astrophysics Data System (ADS)
Chou, C.-C.; Fryxell, B.; Drake, R. P.
2012-03-01
CRASH is a code package developed for the predictive study of radiative shocks. It is based on the BATSRUS MHD code used extensively for space-weather research. We desire to extend the applications of this code to the study of hydrodynamically unstable systems. We report here the results of Rayleigh-Taylor instability (RTI) simulations with CRASH, as a necessary step toward the study of such systems. Our goal, motivated by the previous comparison of simulations and experiment, is to be able to simulate the magnetic RTI with self-generated magnetic fields produced by the Biermann Battery effect. Here we show results for hydrodynamic RTI, comparing the effects of different solvers and numerical parameters. We find that the early-time behavior converges to the analytical result of the linear theory. We observe that the late-time morphology is sensitive to the numerical scheme and limiter beta. At low-resolution limit, the growth of RTI is highly dependent on the setup and resolution, which we attribute to the large numerical viscosity at low resolution.
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.
Non-adiabatic Rayleigh-Taylor instability
NASA Astrophysics Data System (ADS)
Canfield, Jesse; Denissen, Nicholas; Reisner, Jon
2016-11-01
Onset of Rayleigh-Taylor instability (RTI) in a non-adiabatic environment is investigated with the multi-physics numerical model, FLAG. This work was inspired by laboratory experiments of non-adiabatic RTI, where a glass vessel with a layer of tetrahyrdofuran (THF) below a layer of toluene was placed inside a microwave. THF, a polar solvent, readily absorbs electromagnetic energy from microwaves. Toluene, a non-polar solvent, is nearly transparent to microwave heating. The presence of a heat source in the THF layer produced convection and a time-dependent Atwood number (At). The system, initially in stable hydrostatic equilibrium At < 0 , was set into motion by microwave induced, volumetric heating of the THF. The point when At > 0 , indicates that the system is RTI unstable. The observed dominant mode at the onset of RTI was the horizontal length scale of the vessel. This scale is contrary to classical RTI, where the modes start small and increases in scale with time. It is shown that the dominant RTI mode observed in the experiments was determined by the THF length scale prior to RTI. The dominant length scale transitions from the THF to the toluene via the updrafts and downdrafts in the convective cells. This happens when At passes from negative to positive. This work was funded by the Advanced Simulation and Computing Program.
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.
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.
Synthesis of Taylor and Bayliss patterns for linear antenna arrays
NASA Astrophysics Data System (ADS)
Shelton, J. P.
1981-08-01
The history of synthesis techniques for designing linear antenna arrays with low sidelobe patterns is reviewed briefly, and the limitations that are encountered with very low sidelobes and/or small arrays are pointed out. Taylor's continuous aperture synthesis procedure is outlined, and a technique for transforming it for application to a discrete array is described. Discrete-array design equation for Taylor and Bayliss synthesis procedures are given. A set of programs for use on a programmable calculator are presented.
Finite Larmor radius magnetohydrodynamics of the Rayleigh-Taylor instability
NASA Astrophysics Data System (ADS)
Huba, J. D.
1996-07-01
The evolution of the Rayleigh-Taylor instability is studied using finite Larmor radius (FLR) magnetohydrodynamic (MHD) theory. Finite Larmor radius effects are introduced in the momentum equation through an anisotropic ion stress tensor. Roberts and Taylor [Phys. Rev. Lett. 3, 197 (1962)], using fluid theory, demonstrated that FLR effects can stabilize the Rayleigh-Taylor instability in the short-wavelength limit (kLn≫1, where k is the wave number and Ln is the density gradient scale length). In this paper a linear mode equation is derived that is valid for arbitrary kLn. Analytic solutions are presented in both the short-wavelength (kLn≫1) and long-wavelength (kLn≪1) regimes, and numerical solutions are presented for the intermediate regime (kLn˜1). The long-wavelength modes are shown to be the most difficult to stabilize. More important, the nonlinear evolution of the Rayleigh-Taylor instability is studied using a newly developed two-dimensional (2-D) FLR MHD code. The FLR effects are shown to be a stabilizing influence on the Rayleigh-Taylor instability; the short-wavelength modes are the easiest to stabilize, consistent with linear theory. In the nonlinear regime, the FLR effects cause the ``bubbles and spikes'' that develop because of the Rayleigh-Taylor instability to convect along the density gradient and to tilt. Applications of this model to space and laboratory plasma phenomena are discussed.
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.
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…
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…
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 lock...
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...
Does the Taylor Spatial Frame Accurately Correct Tibial Deformities?
Segal, Kira; Ilizarov, Svetlana; Fragomen, Austin T.; Ilizarov, Gabriel
2009-01-01
Background Optimal leg alignment is the goal of tibial osteotomy. The Taylor Spatial Frame (TSF) and the Ilizarov method enable gradual realignment of angulation and translation in the coronal, sagittal, and axial planes, therefore, the term six-axis correction. Questions/purposes We asked whether this approach would allow precise correction of tibial deformities. Methods We retrospectively reviewed 102 patients (122 tibiae) with tibial deformities treated with percutaneous osteotomy and gradual correction with the TSF. The proximal osteotomy group was subdivided into two subgroups to distinguish those with an intentional overcorrection of the mechanical axis deviation (MAD). The minimum followup after frame removal was 10 months (average, 48 months; range, 10–98 months). Results In the proximal osteotomy group, patients with varus and valgus deformities for whom the goal of alignment was neutral or overcorrection experienced accurate correction of MAD. In the proximal tibia, the medial proximal tibial angle improved from 80° to 89° in patients with a varus deformity and from 96° to 85° in patients with a valgus deformity. In the middle osteotomy group, all patients had less than 5° coronal plane deformity and 15 of 17 patients had less that 5° sagittal plane deformity. In the distal osteotomy group, the lateral distal tibial angle improved from 77° to 86° in patients with a valgus deformity and from 101° to 90° for patients with a varus deformity. Conclusions Gradual correction of all tibial deformities with the TSF was accurate and with few complications. Level of Evidence Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence. PMID:19911244
Taylor line swimming in microchannels and cubic lattices of obstacles
NASA Astrophysics Data System (ADS)
Münch, Jan L.; Alizadehrad, Davod; Babu, Sujin B.; Stark, Holger
Microorganisms naturally move in microstructured fluids. Using the simulation method of multi-particle collision dynamics, we study an undulatory Taylor line swimming in a two-dimensional 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.
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.
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
Linear stability of compressible Taylor-Couette flow
NASA Technical Reports Server (NTRS)
Kao, Kai-Hsiung; Chow, Chuen-Yen
1992-01-01
A temporal stability analysis of compressible Taylor-Couette flow is presented. The viscous flow studied in this paper is contained between two concentric cylinders of infinite length, which are rotating with different angular velocities and are kept at different surface temperatures. The effects of differential rotation and temperature difference on the stability of Taylor-Couette flow are contrasted for a range of Mach numbers ranging from incompressible to Mach 3.0. The relative motion of the cylinders dramatically affects the characteristics of the Couette flow at the onset of instability. The flow is stabilized or destabilized depending upon the temperature ratio and speeds of the two cylinders. Independent of Mach number and temperature ratio, increasing Reynolds number generally promotes a destabilizing effect, indicating the inviscid nature of the Taylor-Couette flow.
Photonic arbitrary waveform generator based on Taylor synthesis method.
Liao, Shasha; Ding, Yunhong; Dong, Jianji; Yan, Siqi; Wang, Xu; Zhang, Xinliang
2016-10-17
Arbitrary waveform generation has been widely used in optical communication, radar system and many other applications. We propose and experimentally demonstrate a silicon-on-insulator (SOI) on chip optical arbitrary waveform generator, which is based on Taylor synthesis method. In our scheme, a Gaussian pulse is launched to some cascaded microrings to obtain first-, second- and third-order differentiations. By controlling amplitude and phase of the initial pulse and successive differentiations, we can realize an arbitrary waveform generator according to Taylor expansion. We obtain several typical waveforms such as square waveform, triangular waveform, flat-top waveform, sawtooth waveform, Gaussian waveform and so on. Unlike other schemes based on Fourier synthesis or frequency-to-time mapping, our scheme is based on Taylor synthesis method. Our scheme does not require any spectral disperser or large dispersion, which are difficult to fabricate on chip. Our scheme is compact and capable for integration with electronics.
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.
On using Taylor's hypothesis for three-dimensional mixing layers
NASA Astrophysics Data System (ADS)
LeBoeuf, Richard L.; Mehta, Rabindra D.
1995-06-01
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.
Rayleigh-Taylor instability of violently collapsing bubbles
NASA Astrophysics Data System (ADS)
Lin, Hao; Storey, Brian D.; Szeri, Andrew J.
2002-08-01
In a classical paper Plesset has determined conditions under which a bubble changing in volume maintains a spherical shape. The stability analysis was further developed by Prosperetti to include the effects of liquid viscosity on the evolving shape modes. In the present work the theory is further modified to include the changing density of the bubble contents. The latter is found to be important in violent collapses where the densities of the gas and vapor within a bubble may approach densities of the liquid outside. This exerts a stabilizing influence on the Rayleigh-Taylor mechanism of shape instability of spherical bubbles. A comparison with experimental data shows good agreement with the new theory; the Rayleigh-Taylor instability does provide an extinction threshold for violently collapsing bubbles. It is also explained why earlier works did not produce a slope in the Rayleigh-Taylor stability curve that conforms with that of the present work.
Rayleigh-Taylor instability of cylindrical jets with radial motion
Chen, Xiang M.; Schrock, V.E.; Peterson, P.F.
1995-09-01
Rayleigh-Taylor instability of an interface between fluids with different densities subjected to accelleration normal to itself has interested researchers for almost a century. The classic analyses of a flat interface by Rayleigh and Taylor have shown that this type of instability depends on the direction of acceleration and the density differences of the two fluids. Plesset later analyzed the stability of a spherically symmetric flows (and a spherical interface) and concluded that the instability also depends on the velocity of the interface as well as the direction and magnitude of radial acceleration. The instability induced by radial motion in cylindrical systems seems to have been neglected by previous researchers. This paper analyzes the Rayleigh-Taylor type of the spherical case, the radial velocity also plays an important role. As an application, the example of a liquid jet surface in an Inertial Confinement Fusion (ICF) reactor design is analyzed.
Linear stability of compressible Taylor-Couette flow
NASA Technical Reports Server (NTRS)
Kao, Kai-Hsiung; Chow, Chuen-Yen
1992-01-01
A temporal stability analysis of compressible Taylor-Couette flow is presented. The viscous flow studied in this paper is contained between two concentric cylinders of infinite length, which are rotating with different angular velocities and are kept at different surface temperatures. The effects of differential rotation and temperature difference on the stability of Taylor-Couette flow are contrasted for a range of Mach numbers ranging from incompressible to Mach 3.0. The relative motion of the cylinders dramatically affects the characteristics of the Couette flow at the onset of instability. The flow is stabilized or destabilized depending upon the temperature ratio and speeds of the two cylinders. Independent of Mach number and temperature ratio, increasing Reynolds number generally promotes a destabilizing effect, indicating the inviscid nature of the Taylor-Couette flow.
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
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.
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.
Student understanding of Taylor series expansions in statistical mechanics
NASA Astrophysics Data System (ADS)
Smith, Trevor I.; Thompson, John R.; Mountcastle, Donald B.
2013-12-01
One goal of physics instruction is to have students learn to make physical meaning of specific mathematical expressions, concepts, and procedures in different physical settings. As part of research investigating student learning in statistical physics, we are developing curriculum materials that guide students through a derivation of the Boltzmann factor using a Taylor series expansion of entropy. Using results from written surveys, classroom observations, and both individual think-aloud and teaching interviews, we present evidence that many students can recognize and interpret series expansions, but they often lack fluency in creating and using a Taylor series appropriately, despite previous exposures in both calculus and physics courses.
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.
Solving wave equation using finite differences and Taylor series
NASA Astrophysics Data System (ADS)
Nečasová, Gabriela; Kocina, Filip; Veigend, Petr; Chaloupka, Jan; Šátek, Václav; Kunovský, Jiří
2017-07-01
The paper deals with the numerical solution of partial differential equations (PDEs), especially wave equation. Two methods are used to obtain numerical solution of the wave equation. The Finite Difference Method (FDM) is used for transformation of wave equation to the system of ordinary differential equations (ODEs), different types of difference formulas are used. The influence of arithmetic to higher order difference formulas is also presented. The Modern Taylor Series Method (MTSM) allows to solve ODEs numerically with extremely high precision. An important feature of this method is an automatic integration order setting, i.e. using as many Taylor series terms as the defined accuracy requires.
Pitchfork bifurcations in small aspect ratio Taylor-Couette flow
NASA Astrophysics Data System (ADS)
Mullin, Tom; Satchwell, Doug; Toya, Yorinobu
We present a discussion of steady bifurcation phenomena in Taylor-Couette flow. The emphasis is on the role of pitchfork bifurcations in mathematical models and their relevance to the physical problem. The general features of such bifurcations are reviewed before we discuss the numerical and experimental techniques used to explore their properties. New results are then presented for a wide-gap small aspect ratio version of Taylor-Couette flow. We find good agreement between numerical a nd experimental results and show that the qualitative features of the bifurcation sequence are the same as those found with other radius ratios.
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.
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
ERIC Educational Resources Information Center
Diodato, Virgil P.
1981-01-01
Discusses the effectiveness of using author-supplied indexing to increase subject control in information retrieval, and describes a study which compared author indexing for articles published in "American Mathematical Society" journals to indexing of the same articles by an editor of "Mathematical Reviews." Nine references are…
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.
Evidence for mate guarding behavior in the Taylor's checkerspot butterfly
Victoria J. Bennett; Winston P. Smith; Matthew G. Betts
2011-01-01
Discerning the intricacies of mating systems in butterflies can be difficult, particularly when multiple mating strategies are employed and are cryptic and not exclusive. We observed the behavior and habitat use of 113 male Taylor's checkerspot butterflies (Euphydryas editha taylori). We confirmed that two distinct mating strategies were...
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
Tree ecophysiology research at Taylor Woods (P-53)
Thomas E. Kolb; Nate G. McDowell
2008-01-01
We summarize the key findings of tree ecophysiology studies performed at Taylor Woods, Fort Valley Experimental Forest, Arizona between 1994 and 2003 that provide unique insight on impacts of long-term stand density management in ponderosa pine forests on tree water relations, leaf gas exchange, radial growth, leaf area-to-sapwood-area ratio, growth efficiency, leaf...
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.
Turbulent strength in ultimate Taylor-Couette turbulence
NASA Astrophysics Data System (ADS)
Ezeta, Rodrigo; Huisman, Sander G.; Sun, Chao; Lohse, Detlef
2016-11-01
We provide the local scaling of the Taylor-Reynolds number (Reλ) as a function of driving strength (Ta), in the ultimate regime of Taylor-Couette flow for the inner cylinder rotation case. The calculation is done via local flow measurements using Particle Image Velocimetry (PIV) to reconstruct the velocity fields. We approximate the value of the local dissipation rate ɛ (r) using the scaling for the second order structure functions in the longitudinal and transversal directions within the inertial regime where Taylor's hypothesis is not invoked. We find an effective local scaling of < ɛ (r) > r / (ν3d-4) Ta 1 . 4 , which is the same as the global dissipation rate obtained from both torque measurements and Direct Numerical Simulations (DNS). Additionally, we calculate the Kolmogorov length scale and find < η (r) > r / d Ta - 0 . 35 . The turbulence intensity is also calculated and it is found to scale with the driving strength as iθ Ta - 0 . 056 . Finally, with both the local dissipation rate and the local fluctuations available we find that the Taylor-Reynolds number scales as Reλ Ta 0 . 18 . Stichting voor Fundamenteel Onderzoek der Materie (FOM).
Taylor vortices formed in the melt during paratellurite crystal growth
Kolesnikov, A. I. Grechishkin, R. M.; Tret'yakov, S. A.; Gritsunova, O. V.; Vorontsova, E. Yu.
2008-12-15
The hydrodynamics of tellurium dioxide melt during Czochralski growth of paratellurite crystals with a diameter up to 80 mm was experimentally investigated. The images of the melt surface during crystal growth are obtained. It is shown that a stable system of Taylor vortices in the form of two convection cells is formed at definite Reynolds numbers.
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)
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…
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
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.
Multiple Representations and the Understanding of Taylor Polynomials
ERIC Educational Resources Information Center
Habre, Samer
2009-01-01
The study of Maclaurin and Taylor polynomials entails the comprehension of various new mathematical ideas. Those polynomials are initially discussed at the college level in a calculus class and then again in a course on numerical methods. This article investigates the understanding of these polynomials by students taking a numerical methods class…
Some observations of a sheared Rayleigh-Taylor/Benard instability
NASA Technical Reports Server (NTRS)
Humphrey, J. A. C.; Marcus, D. L.
1987-01-01
An account is provided of preliminary flow visualization observations made in an unstably stratified flow with shear superimposed. The structures observed appear to be the superposition of a Rayleigh-Taylor/Benard instability and a Kelvin-Helmholtz instability. Aside from its intrinsic fundamental value, the study of these structures is of special interest to theoreticians developing nonlinear stability calculation methodologies.
Taylor-Couette flow with radial fluid injection
NASA Astrophysics Data System (ADS)
Wilkinson, Nikolas; Dutcher, Cari S.
2017-08-01
Taylor-Couette cells have been shown to improve a number of industrial processes due to the wide variety of hydrodynamic flow states accessible. Traditional designs, however, limit the ability to introduce new fluids into the annulus during device operation due to geometric confinement and complexity. In this paper, a co- and counter-rotating Taylor-Couette cell with radial fluid injection has been constructed. The incorporation of 16 ports in the inner cylinder enables radial fluid injection during rotation of both cylinders. The design is also capable of continuous axial flow, enabling large injection volumes. The new inner cylinder design does not modify the critical Re for flow instabilities and can precisely inject a desired mass at a desired flow rate. A range of injection rates and masses were explored to quantify the effect of radial injection on the stability of the turbulent Taylor vortex structure. Only the highest injection rate and total mass studied (5.9 g/s, 100 g) modified the turbulent Taylor vortex structure after injection for a sustained period. The post-injection vortices remained larger than the pre-injection vortices, whereas at lower injection rates or masses, the vortex structure quickly returned to the pre-injection structure. This new system allows for in situ study of hydrodynamic effects on fluid-fluid (gas and liquid) mixing and multiphase complexation, growth, and structure. We demonstrated this new design's potential for studying the flocculation of bentonite using cationic polyacrylamide for enhancing water treatment operations.
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)
Why We Will Lose: Taylorism in America's High Schools.
ERIC Educational Resources Information Center
Gray, Kenneth
1993-01-01
Taylorism (rewards based on merit) and tracking in high schools should be abolished because these practices alienate successful students from less successful ones and encourage elitism instead of egalitarianism. Curriculum integration may be achieved by creating opportunities for student interaction in various existing subject areas. Teamwork and…
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)
Why We Will Lose: Taylorism in America's High Schools.
ERIC Educational Resources Information Center
Gray, Kenneth
1993-01-01
Taylorism (rewards based on merit) and tracking in high schools should be abolished because these practices alienate successful students from less successful ones and encourage elitism instead of egalitarianism. Curriculum integration may be achieved by creating opportunities for student interaction in various existing subject areas. Teamwork and…
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)
On implicit Taylor series methods for stiff ODEs
Kirlinger, G. . Inst. fuer Angewandte und Numerische Mathematik); Corliss, G.F. )
1991-01-01
Several versions of implicit Taylor series methods (ITSM) are presented and evaluated. Criteria for the approximate solution of ODEs via ITSM are given. Some ideas, motivations, and remarks on the inclusion of the solution of stiff ODEs are outlined. 25 refs., 3 figs.
On implicit Taylor series methods for stiff ODEs
Kirlinger, G.; Corliss, G.F.
1991-12-31
Several versions of implicit Taylor series methods (ITSM) are presented and evaluated. Criteria for the approximate solution of ODEs via ITSM are given. Some ideas, motivations, and remarks on the inclusion of the solution of stiff ODEs are outlined. 25 refs., 3 figs.
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…
Some observations of a sheared Rayleigh-Taylor/Benard instability
NASA Technical Reports Server (NTRS)
Humphrey, J. A. C.; Marcus, D. L.
1987-01-01
An account is provided of preliminary flow visualization observations made in an unstably stratified flow with shear superimposed. The structures observed appear to be the superposition of a Rayleigh-Taylor/Benard instability and a Kelvin-Helmholtz instability. Aside from its intrinsic fundamental value, the study of these structures is of special interest to theoreticians developing nonlinear stability calculation methodologies.
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.
The construction of exact Taylor states. I: The full sphere
NASA Astrophysics Data System (ADS)
Livermore, P. W.; Ierley, G.; Jackson, A.
2009-11-01
The dynamics of the Earth's fluid core are described by the so-called magnetostrophic balance between Coriolis, pressure, buoyancy and Lorentz forces. In this regime the geomagnetic field is subject to a continuum of theoretical conditions, which together comprise Taylor's constraint, placing restrictions on its internal structure. Examples of such fields, so-called Taylor states, have proven difficult to realize except in highly restricted cases. In previous theoretical developments, we showed that it was possible to reduce this infinite class of conditions to a finite number of coupled quadratic homogeneous equations when adopting a certain regular truncated spectral expansion for the magnetic field. In this paper, we illustrate the power of these results by explicitly constructing two families of exact Taylor states in a full sphere that match the same low-degree observationally derived model of the radial field at the core-mantle boundary. We do this by prescribing a smooth purely poloidal field that fits this observational model and adding to it an expediently chosen unconstrained set of interior toroidal harmonics of azimuthal wavenumbers 0 and 1. Formulated in terms of the toroidal coefficients, the resulting system is purely linear and can be readily solved to find Taylor states. By calculating the extremal members of the two families that minimize the Ohmic dissipation, we argue on energetic ground that the toroidal field in the Earth's core is likely to be dominated by low order azimuthal modes, similar to the observed poloidal field. Finally, we comment on the extension of finding Taylor states within a general truncated spectral expansion with arbitrary poloidal and toroidal coefficients.
2005-06-01
diameter (Photograph 2). Drill log samples collected from Taylor Mountain indicate that a moderately weathered granodiorite extends to 10 feet below...ground surface followed by granodiorite bedrock. Regional geology maps indicate that Kechumstuk Mountain has the similar lithology. 3.1.3.3 Soils
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.
Application of software complex turbo problem solver to rayleigh-taylor instability modeling
NASA Astrophysics Data System (ADS)
Fortova, S. V.; Utkin, P. S.; Shepelev, V. V.
2016-10-01
The dynamic processes which take place during high-speed impact of two metal plates with different densities are investigated using three-dimensional numerical simulations. It is shown that as a result of the impact the Rayleigh-Taylor instability forms which leads to the formation of three-dimensional ring-shaped structures on the surface of the metal with smaller density. The comparative analysis of the metals interface deformation process with the use of different equations of state is performed. The numerical study is carried out by means of special software complex Turbo Problem Solver developed by the authors. The software complex Turbo Problem Solver implements generalized approach to the construction of hydrodynamic code for various computational fluid dynamics problems. Turbo Problem Solver provides several numerical schemes and software blocks to set initial, boundary conditions and mass forces. The solution of test problem about Rayleigh-Taylor instability growth and development for the case of very rapid density growth is also presented.
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.
Crane, Judy L
2015-01-01
This letter to the editor rebuts flawed analyses made by O'Reilly (2014) and points out duplicative comments that have already been rebutted in the peer-reviewed literature. O'Reilly (2014) provides little new scientific information on the source apportionment of polycyclic aromatic hydrocarbons (PAHs) in sediments, and the author stands by the results of her research.
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…
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.
Beyond linear fields: the Lie-Taylor expansion
NASA Astrophysics Data System (ADS)
Arter, Wayne
2017-01-01
The work extends the linear fields' solution of compressible nonlinear magnetohydrodynamics (MHD) to the case where the magnetic field depends on superlinear powers of position vector, usually, but not always, expressed in Cartesian components. Implications of the resulting Lie-Taylor series expansion for physical applicability of the Dolzhansky-Kirchhoff (D-K) equations are found to be positive. It is demonstrated how resistivity may be included in the D-K model. Arguments are put forward that the D-K equations may be regarded as illustrating properties of nonlinear MHD in the same sense that the Lorenz equations inform about the onset of convective turbulence. It is suggested that the Lie-Taylor series approach may lead to valuable insights into other fluid models.
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.
Pediatric and adolescent applications of the Taylor Spatial Frame.
Paloski, Michael; Taylor, Benjamin C; Iobst, Christopher; Pugh, Kevin J
2012-06-01
Limb deformity can occur in the pediatric and adolescent populations from multiple etiologies: congenital, traumatic, posttraumatic sequelae, oncologic, and infection. Correcting these deformities is important for many reasons. Ilizarov popularized external fixation to accomplish this task. Taylor expanded on this by designing an external fixator in 1994 with 6 telescoping struts that can be sequentially manipulated to achieve multiaxial correction of deformity without the need for hinges or operative frame alterations. This frame can be used to correct deformities in children and has shown good anatomic correction with minimal morbidity. The nature of the construct and length of treatment affects psychosocial factors that the surgeon and family must be aware of prior to treatment. An understanding of applications of the Taylor Spatial Frame gives orthopedic surgeons an extra tool to correct simple and complex deformities in pediatric and adolescent patients.
Intraoperative measurement of mounting parameters for the Taylor Spatial Frame.
Gantsoudes, George D; Fragomen, Austin T; Rozbruch, S Robert
2010-04-01
The Taylor Spatial Frame (Smith & Nephew, Memphis, TN) is a powerful tool in providing gradual correction of deformity. The Taylor Spatial Frame has the potential to allow for very accurate corrections achieved over one or more schedules through the use of the software on www.spatialframe.com. The accuracy of the frame is contingent upon the input of precise parameters. The correction occurs about a virtual hinge in space called the origin. The location of the origin is defined by its spatial relationship to the reference ring. Mounting parameters are the measurements that define the location of the origin (virtual hinge). We present a simple practical method for obtaining mounting parameters during surgery using standard equipment.
Taylor bubbles in liquid filled annuli: Some new observations
NASA Astrophysics Data System (ADS)
Agarwal, V.; Jana, A. K.; Das, G.; Das, P. K.
2007-10-01
Taylor bubbles rising through a vertical concentric annulus do not wrap around the inner tube completely. The two edges of the bubble are separated by a liquid bridge which increases with an increase of the inner radius. However, the change in the shape of the Taylor bubbles in annuli with extremely small inner diameter has not yet been reported. In the present investigation, several experiments have been performed in circular and noncircular annuli to understand the influence of the inner and outer wall on the bubble shape. The bubble has been observed to assume a completely different shape in both circular and square annuli with a very thin inner rod. Nevertheless, the rise velocity for such situations agree with the prediction of the model proposed by Das et al. [Chem. Eng. Sci. 53, 977 (1998)] when the outer pipe is circular but fails for a square outer pipe.
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.
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.
Effect of Charge Density on the Taylor Cone in Electrospinning
NASA Astrophysics Data System (ADS)
Stanger, Jonathan; Tucker, Nick; Kirwan, Kerry; Staiger, Mark P.
A detailed understanding of charge density and its origins during the electrospinning process is desirable for developing new electrospinnable polymer-solvent systems and ensuring mathematical models of the process are accurate. In this work, two different approaches were taken to alter the charge density in order to measure its effect on the Taylor cone, mass deposition rate and initial jet diameter. It was found that an increase in charge density results in a decrease in the mass deposition rate and initial jet diameter. A theory is proposed for this behaviour in that an increase in charge density leads to the tip of the Taylor cone forming a smaller radius of curvature resulting in the concentration of electric stresses at the tip. This leads to the electrostatic forces drawing the initial jet from a smaller effective area or "virtual orifice".
Slavnov-Taylor Identities from the Causal Point of View
NASA Astrophysics Data System (ADS)
Dütsch, Michael
We continue the investigation of quantized Yang-Mills theories coupled to matter fields in the framework of causal perturbation theory which goes back to Epstein and Glaser. In this approach gauge invariance is expressed by a simple commutator relation for the S matrix and the corresponding gauge transformations are simple transformations of the free fields only. In spite of this simplicity, gauge invariance implies the usual Slavnov-Taylor identities. The main purpose of this paper is to prove the latter statement. Since the Slavnov-Taylor identities are formulated in terms of Green functions, we investigate the agreement of two perturbative definitions of Green functions, namely Epstein and Glaser's definition with the Gell-Mann-Low series.
Anisotropy and feedthrough in magneto-Rayleigh-Taylor instability
Lau, Y. Y.; Zier, J. C.; Rittersdorf, I. M.; Weis, M. R.; Gilgenbach, R. M.
2011-06-15
The magneto-Rayleigh-Taylor instability (MRT) of a finite slab is studied analytically using the ideal MHD model. The slab may be accelerated by an arbitrary combination of magnetic pressure and fluid pressure, thus allowing an arbitrary degree of anisotropy intrinsic to the acceleration mechanism. The effect of feedthrough in the finite slab is also analyzed. The classical feedthrough solution obtained by Taylor in the limit of zero magnetic field, the single interface MRT solution of Chandrasekhar in the limit of infinite slab thickness, and Harris' stability condition on purely magnetic driven MRT, are all readily recovered in the analytic theory as limiting cases. In general, we find that MRT retains robust growth if it exists. However, feedthrough may be substantially reduced if there are magnetic fields on both sides of the slab, and if the MRT mode invokes bending of the magnetic field lines.
Anisotropy and feedthrough in magneto-Rayleigh-Taylor instability.
Lau, Y Y; Zier, J C; Rittersdorf, I M; Weis, M R; Gilgenbach, R M
2011-06-01
The magneto-Rayleigh-Taylor instability (MRT) of a finite slab is studied analytically using the ideal MHD model. The slab may be accelerated by an arbitrary combination of magnetic pressure and fluid pressure, thus allowing an arbitrary degree of anisotropy intrinsic to the acceleration mechanism. The effect of feedthrough in the finite slab is also analyzed. The classical feedthrough solution obtained by Taylor in the limit of zero magnetic field, the single interface MRT solution of Chandrasekhar in the limit of infinite slab thickness, and Harris' stability condition on purely magnetic driven MRT, are all readily recovered in the analytic theory as limiting cases. In general, we find that MRT retains robust growth if it exists. However, feedthrough may be substantially reduced if there are magnetic fields on both sides of the slab, and if the MRT mode invokes bending of the magnetic field lines.
Influence of velocity shear on the Rayleigh-Taylor instability
Guzdar, P.N.; Satyanarayana, P.; Huba, J.D.; Ossakow, S.L.
1982-05-01
The influence of a transverse velocity shear on the Rayleigh-Taylor instability is investigated. It is found that a sheared velocity flow can substantially reduce the growth rate of the Rayleigh-Taylor instability in short wavelength regime (i.e., kL>1 where L is the scale length of the density inhomogeneity), and causes the growth rate to maximize at kL<1.0. Applications of this result to ionospheric phenomena (equatorial spread F (ESF) and ionospheric plasma clouds) are discussed. In particular, the effect of shear could account for, at times, the 100's of km modulation observed on the bottomside of the ESF ionosphere and the km scale size wavelengths observed in barium cloud prompt striation phenomena.
Beyond linear fields: the Lie-Taylor expansion.
Arter, Wayne
2017-01-01
The work extends the linear fields' solution of compressible nonlinear magnetohydrodynamics (MHD) to the case where the magnetic field depends on superlinear powers of position vector, usually, but not always, expressed in Cartesian components. Implications of the resulting Lie-Taylor series expansion for physical applicability of the Dolzhansky-Kirchhoff (D-K) equations are found to be positive. It is demonstrated how resistivity may be included in the D-K model. Arguments are put forward that the D-K equations may be regarded as illustrating properties of nonlinear MHD in the same sense that the Lorenz equations inform about the onset of convective turbulence. It is suggested that the Lie-Taylor series approach may lead to valuable insights into other fluid models.
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…
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…
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.
Nested Taylor decomposition of univariate functions under fluctuationlessness approximation
NASA Astrophysics Data System (ADS)
Gürvit, Ercan; Baykara, N. A.
2014-10-01
Taylor decomposition of an analytic function and the use of the remainder part of this decomposition expressed in integral form on which Fluctuationlessness theorem is applied was already known in the litterature, but application of Fluctuationlessness approximation twice on the remainder part adds up an amelioration to the approximation. Organisation of the decomposition in such a way that this is made possible is explained in detail in this work.
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.
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.
Linear instability in Rayleigh-stable Taylor-Couette flow
NASA Astrophysics Data System (ADS)
Deguchi, Kengo
2017-02-01
Rayleigh's stability criterion describes the inviscid stability of rotating fluid flows. Despite the limitations of the criterion due to the assumptions used, it has been widely viewed as a general stability barrier in various rapidly rotating flows. However, contrary to previous belief, a linear instability is identified in Rayleigh-stable Taylor-Couette flow. The instability is found in cyclonic rapid rotation regime, for almost the entire range of the radius ratio of the cylinders.
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).
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.
Ablative stabilization of the deceleration phase rayleigh-taylor instability
Lobatchev; Betti
2000-11-20
The growth rates of the deceleration-phase Rayleigh-Taylor instability for imploding inertial confinement fusion capsules are calculated and compared with the results of numerical simulations. It is found that the unstable spectrum and the growth rates are significantly reduced by the finite ablation flow at the shell's inner surface. For typical direct-drive capsules designed for the National Ignition Facility, the unstable spectrum exhibits a cutoff for l approximately 90.
Linear instability in Rayleigh-stable Taylor-Couette flow.
Deguchi, Kengo
2017-02-01
Rayleigh's stability criterion describes the inviscid stability of rotating fluid flows. Despite the limitations of the criterion due to the assumptions used, it has been widely viewed as a general stability barrier in various rapidly rotating flows. However, contrary to previous belief, a linear instability is identified in Rayleigh-stable Taylor-Couette flow. The instability is found in cyclonic rapid rotation regime, for almost the entire range of the radius ratio of the cylinders.
Nonlinear Rayleigh-Taylor instability of rotating inviscid fluids.
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.
Subcritical dynamo bifurcation in the Taylor-Green flow.
Ponty, Y; Laval, J-P; Dubrulle, B; Daviaud, F; Pinton, J-F
2007-11-30
We report direct numerical simulations of dynamo generation for flow generated using a Taylor-Green forcing. We find that the bifurcation is subcritical and show its bifurcation diagram. We connect the associated hysteretic behavior with hydrodynamics changes induced by the action of the Lorentz force. We show the geometry of the dynamo magnetic field and discuss how the dynamo transition can be induced when an external field is applied to the flow.
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.
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.
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.
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.
Boundary effects and the onset of Taylor vortices
NASA Astrophysics Data System (ADS)
Rucklidge, A. M.; Champneys, A. R.
2004-05-01
It is well established that the onset of spatially periodic vortex states in the Taylor-Couette flow between rotating cylinders occurs at the value of Reynolds number predicted by local bifurcation theory. However, the symmetry breaking induced by the top and bottom plates means that the true situation should be a disconnected pitchfork. Indeed, experiments have shown that the fold on the disconnected branch can occur at more than double the Reynolds number of onset. This leads to an apparent contradiction: why should Taylor vortices set in so sharply at the Reynolds number predicted by the symmetric theory, given such large symmetry-breaking effects caused by the boundary conditions? This paper offers a generic explanation. The details are worked out using a Swift-Hohenberg pattern formation model that shares the same qualitative features as the Taylor-Couette flow. Onset occurs via a wall mode whose exponential tail penetrates further into the bulk of the domain as the driving parameter increases. In a large domain of length L, we show that the wall mode creates significant amplitude in the centre at parameter values that are O( L-2) away from the value of onset in the problem with ideal boundary conditions. We explain this as being due to a Hamiltonian Hopf bifurcation in space, which occurs at the same parameter value as the pitchfork bifurcation of the temporal dynamics. The disconnected anomalous branch remains O(1) away from the onset parameter since it does not arise as a bifurcation from the wall mode.
Taylor--Couette--Poiseuille flow with a permeable inner cylinder
NASA Astrophysics Data System (ADS)
Tilton, Nils; Martinand, Denis; Serre, Eric; Lueptow, Richard
2010-11-01
We consider laminar Taylor--Couette--Poiseuille flow between an outer, fixed, impermeable cylinder and a concentric, inner, rotating, permeable cylinder with radial suction. Due to centrifugal instabilities the steady flow transitions to Taylor vortex flow. This system is used in filtration because the vortices wash contaminants away from the permeable cylinder. The coupling between the axial pressure drop driving the annular Poiseuille flow, and the transmembrane pressure driving the suction induces axial variations of the velocity field of the subcritical flow, which can evolve from suction to injection (cross flow reversal) or consume the whole axial flow (axial flow exhaustion). Moreover, the stability of this flow departs from that of Taylor--Couette flow. We propose an asymptotic solution to the subcritical flow assuming slow axial variations of the velocity and pressure fields. The transmembrane suction and pressure are coupled through Darcy's law. This solution is then used as a base flow to study the appearance of instabilities in the form of global modes. The analytical results for the subcritical and supercritical flows are then compared with dedicated 3-D spectral direct numerical simulations implementing Darcy's law on the inner cylinder.
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.
Patterns of the turbulent Taylor-Couette flow
NASA Astrophysics Data System (ADS)
Prigent, Arnaud; Talioua, Abdessamad; Mutabazi, Innocent
2016-11-01
We are interested in the study of the transition to turbulence in the Taylor-Couette flow, the flow between two independently rotating coaxial cylinders. Once the geometry is fixed, the flow is controlled by the inner and outer Reynolds numbers and present a large variety of flow regimes. In counter-rotation, the transition is characterized by a succession of more or less turbulent flow regimes: intermittency with turbulent spots, spiral turbulence, featureless turbulence. For larger values of the inner Reynolds number, turbulent Taylor roll re-emerge from the featureless turbulence and remain for very large values of the Reynolds numbers. Bifurcations between different turbulent rolls states are even observed in the ultimate turbulence regime. Nevertheless the transition from the featureless turbulence to the turbulent rolls still requires a detailed study and the mechanism which causes and sustains turbulent spots or turbulent spirals remains unknown. In this study we present new experimental information on the organization of the flow for the different regimes with turbulence. The experiments are conducted in a Taylor-Couette flow with η = 0 . 8 . Stereo-Particle Image Velocimetry measurements and visualizations of the different flow regimes are realized and discussed. This work was supported by the ANR TRANSFLOW - ANR-13-BS09-0025.
Reconnaissance study of the Taylor Mountains pluton, southwestern Alaska
Hudson, Travis L.; Miller, Marti L.; Klimasauskas, Edward P.; Layer, Paul W.
2010-01-01
The Taylor Mountains pluton is a Late Cretaceous to early Tertiary (median age 65 + or ? 2 Ma) epizonal, composite biotite granite stock located about 235 km (145 mi) northeast of Dillingham in southwestern Alaska. This 30 km2 (12 mi2) pluton has sharp and discordant contacts with hornfels that developed in Upper Cretaceous clastic sedimentary rocks of the Kuskokwim Group. The three intrusive phases in the Taylor Mountains pluton, in order of emplacement, are (1) porphyritic granite containing large K-feldspar phenocrysts in a coarse-grained groundmass, (2) porphyritic granite containing large K-feldspar and smaller, but still coarse, plagioclase, quartz, and biotite phenocrysts in a fine-grained groundmass, and (3) fine-grained, leucocratic, equigranular granite. The porphyritic granites have different emplacement histories, but similar compositions; averages are 69.43 percent SiO2, 1.62 percent CaO, 5.23 percent FeO+MgO, 3.11 percent Na2O, and 4.50 percent K2O. The fine-grained, equigranular granite is distinctly felsic compared to porphyritic granite; it averages 75.3 percent SiO2, 0.49 percent CaO, 1.52 percent FeO+MgO, 3.31 percent Na2O, and 4.87 percent K2O. Many trace elements including Ni, Cr, Sc, V, Ba, Sr, Zr, Y, Nb, La, Ce, Th, and Nd are strongly depleted in fine-grained equigranular granite. Trace elements are not highly enriched in any of the granites. Known hydrothermal alteration is limited to one tourmaline-quartz replacement zone in porphyritic granite. Mineral deposits in the Taylor Mountains area are primarily placer gold (plus wolframite, cassiterite, and cinnabar); sources for these likely include scattered veins in hornfels peripheral to the Taylor Mountain pluton. The granite magmas that formed the Taylor Mountains pluton are thought to represent melted continental crust that possibly formed in response to high heat flow in the waning stage of Late Cretaceous subduction beneath interior Alaska.
NASA Astrophysics Data System (ADS)
Toner, Jonathan D.; Sletten, Ronald S.; Prentice, Michael L.
2013-03-01
salt accumulations in soils of Taylor Valley, Antarctica, provide a history of paleolakes and the advance of the Ross Sea Ice Sheet (RSIS). In western Taylor Valley, soluble salt accumulations are relatively high and are composed primarily of Na+, Ca2+, Cl-, and SO42-. In eastern Taylor Valley, soluble salt accumulations are much lower and are composed primarily of Na+ and HCO3-. Na-HCO3-rich compositions in eastern Taylor Valley are formed through leaching, calcite dissolution, and cation exchange reactions and appear to influence the chemistry of nearby streams and lakes. The data presented here support hypotheses that a lobe of the RSIS expanded into eastern Taylor Valley and dammed proglacial paleolakes. However, in contrast to previous studies, our findings indicate that the RSIS advanced deeper into Taylor Valley and that paleolakes were less extensive. By comparing soluble salt distributions across Taylor Valley, we conclude that a lobe of the RSIS filled all of eastern Taylor Valley and dammed paleolakes in western Taylor Valley up to approximately 300 m elevation. Following ice retreat, smaller paleolakes formed in both western and eastern Taylor Valley up to about 120 m elevation, with prominent still-stands controlled by the elevation of major valley thresholds. At higher elevations, soluble salt accumulations are consistent with older soils that have not been affected by the most recent RSIS advance.
Bright and durable field emission source derived from refractory taylor cones
Hirsch, Gregory
2016-12-20
A method of producing field emitters having improved brightness and durability relying on the creation of a liquid Taylor cone from electrically conductive materials having high melting points. The method calls for melting the end of a wire substrate with a focused laser beam, while imposing a high positive potential on the material. The resulting molten Taylor cone is subsequently rapidly quenched by cessation of the laser power. Rapid quenching is facilitated in large part by radiative cooling, resulting in structures having characteristics closely matching that of the original liquid Taylor cone. Frozen Taylor cones thus obtained yield desirable tip end forms for field emission sources in electron beam applications. Regeneration of the frozen Taylor cones in-situ is readily accomplished by repeating the initial formation procedures. The high temperature liquid Taylor cones can also be employed as bright ion sources with chemical elements previously considered impractical to implement.
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.
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.
Pruning to Increase Taylor Dispersion in Physarum polycephalum Networks.
Marbach, Sophie; Alim, Karen; Andrew, Natalie; Pringle, Anne; Brenner, Michael P
2016-10-21
How do the topology and geometry of a tubular network affect the spread of particles within fluid flows? We investigate patterns of effective dispersion in the hierarchical, biological transport network formed by Physarum polycephalum. We demonstrate that a change in topology-pruning in the foraging state-causes a large increase in effective dispersion throughout the network. By comparison, changes in the hierarchy of tube radii result in smaller and more localized differences. Pruned networks capitalize on Taylor dispersion to increase the dispersion capability.
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.
Statistical approach of weakly nonlinear ablative Rayleigh-Taylor instability
Garnier, J.; Masse, L.
2005-06-15
A weakly nonlinear model is proposed for the Rayleigh-Taylor instability in presence of ablation and thermal transport. The nonlinear effects for a single-mode disturbance are computed, included the nonlinear correction to the exponential growth of the fundamental modulation. Mode coupling in the spectrum of a multimode disturbance is thoroughly analyzed by a statistical approach. The exponential growth of the linear regime is shown to be reduced by the nonlinear mode coupling. The saturation amplitude is around 0.1{lambda} for long wavelengths, but higher for short instable wavelengths in the ablative regime.
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
Simulating the Rayleigh-Taylor instability with the Ising model
Ball, Justin R.; Elliott, James B.
2011-08-26
The Ising model, implemented with the Metropolis algorithm and Kawasaki dynamics, makes a system with its own physics, distinct from the real world. These physics are sophisticated enough to model behavior similar to the Rayleigh-Taylor instability and by better understanding these physics, we can learn how to modify the system to better re ect reality. For example, we could add a v_{x} and a v_{y} to each spin and modify the exchange rules to incorporate them, possibly using two body scattering laws to construct a more realistic system.
Hypertension as a complication of Taylor spatial frame.
Changulani, Manesh; Bradbury, Mark; Zenios, Michalis
2009-11-01
Circular external fixators in children are widely used for limb lengthening, deformity correction and the treatment of fractures. We report a case of successful management of hypertension in a 13-year-old treated with a Taylor spatial frame after a road traffic accident and a tibial fracture. A heightened awareness of the association of hypertension and external fixators is required to improve patient outcomes. Outcomes are improved by prompt diagnosis and treatment of hypertension, preventing hypertensive end-organ damage, choice of an appropriate first line antihypertensive treatment, and not subjecting children to invasive investigations looking for an alternative secondary cause of hypertension.
Saffman-Taylor instability for generalized Newtonian fluids.
Mora, S; Manna, M
2009-07-01
We study theoretically the linear Saffman-Taylor instability for non-Newtonian fluids in a Hele-Shaw cell. After introducing the notion of generalized Newtonian fluid we calculate the associated Darcy's law. We derive the relation governing the growth rate of normal modes for a large class of non-Newtonian flows. For shear-thinning fluids at high shear rate our theory provides Darcy's laws free of the nonphysical divergences appearing in the classical approaches. We characterize fluids which develop instabilities faster than Newtonian fluids under the same hydrodynamical conditions. Another primary result that this paper provides is that for some shear-thickening fluids, all normal modes are stable.
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.
Onset of cellular motion in Taylor-Couette flow
NASA Astrophysics Data System (ADS)
Mullin, T.; Heise, M.; Pfister, G.
2017-08-01
Taylor-Couette flow between concentric rotating cylinders provides a prime example of a pitchfork bifurcation in hydrodynamic stability. However, more than 40 years ago, Benjamin pointed out difficulties in establishing quantitative links between models where periodicity is assumed along the length of the cylinders and calculations using the Navier-Stokes equations. A new model was recently advanced where it is claimed that the bifurcation which is relevant to the onset of cellular motion is the one between neighboring states. Here, we provide experimental data in support of this idea which explain why the onset of cellular motion is observed to be sharp whereas the periodic model bifurcation is highly imperfect.
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.
Lattice QCD for Baryon Rich Matter - Beyond Taylor Expansions
NASA Astrophysics Data System (ADS)
Bornyakov, V.; Boyda, D.; Goy, V.; Molochkov, A.; Nakamura, A.; Nikolaev, A.; Zakharov, V. I.
2016-12-01
We discuss our study for exploring the QCD phase diagram based on the lattice QCD. To go beyond the Taylor expansion and to reach higher density regions, we employ the canonical approach. In order to produce lattice data which meet experimental situation as much as possible, we propose a canonical approach with the charge and baryon number. We present our lattice QCD GPU code for this project which employs the clover improved Wilson fermions and Iwasaki gauge action to investigate pure imaginary chemical potential.
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.
Nonlinear theory of the ablative Rayleigh-Taylor instability.
Sanz, J; Ramírez, J; Ramis, R; Betti, R; Town, R P J
2002-11-04
A fully nonlinear sharp-boundary model of the ablative Rayleigh-Taylor instability is derived and closed in a similar way to the self-consistent closure of the linear theory. It contains the stabilizing effect of ablation and accurately reproduces the results of 2D DRACO simulations. The single-mode saturation amplitude, bubble and spike evolutions in the nonlinear regimes, and the seeding of long-wavelength modes via mode coupling are determined and compared with the classical theory without ablation. Nonlinear stability above the linear cutoff is also predicted.
Rayleigh-Taylor instability under a flat beam.
Lenschen, M; Calvo, A; Cachile, M
2010-01-01
A theoretical and experimental study on the Rayleigh-Taylor instability of a thin liquid film is presented. The experiments were performed by coating the underside of a flat beam with uniform liquid film. The size of the beam is such that a linear arrangement of drops is formed allowing the measurement of the drops growth. The experimental growth of the drops has been compared to the results obtained from a stability analysis performed on the equation that controls the thickness evolution and an excellent agreement is found. In addition, both time and length scales of the phenomenon are established.
Rayleigh-Taylor instability in a sedimenting suspension.
Völtz, C; Pesch, W; Rehberg, I
2002-01-01
The temporal evolution of an interface between glycerin and a glycerin-sand suspension of small packing fraction (obtained using the hindered settling phenomenon) driven by gravity is experimentally investigated. The growth rates for the different wave numbers characterizing the developing front are determined by means of a Fourier analysis. To model the observed behavior, we apply the idea of the Rayleigh-Taylor instability for a homogeneous fluid with vertically varying density and viscosity (one-fluid model). A good agreement between the experimental and theoretical results is obtained.
Rayleigh-taylor instability with magnetic fluids: experiment and theory
Pacitto; Flament; Bacri; Widom
2000-12-01
We present experiments showing the Rayleigh-Taylor instability at the interface between a dense magnetic liquid and an immiscible less dense liquid. The liquids are confined in a Hele-Shaw cell and a magnetic field is applied perpendicular to the cell. We measure the wavelength and the growth rate at the onset of the instability as a function of the external magnetic field. The wavelength decreases as the field increases. The amplitude of the interface deformation grows exponentially with time in the early stage, and the growth rate is an increasing function of the field. These results are compared to theoretical predictions given in the framework of linear stability analysis.
Weakly nonlinear theory for the ablative Rayleigh-Taylor instability.
Garnier, J; Raviart, P-A; Cherfils-Clérouin, C; Masse, L
2003-05-09
A weakly nonlinear model is proposed for the Rayleigh-Taylor instability in the presence of ablation and thermal transport. The second harmonic generation efficiency of a single-mode disturbance is computed, as well as the nonlinear correction to the exponential growth of the fundamental modulation. Mode coupling in the spectrum of a multimode disturbance is thoroughly analyzed. The ablative stabilization can be clearly discussed because the derived formulas for the evanescent ablation rate are in agreement with previously known results for incompressible, inviscid, irrotational, and immiscible fluids [S. W. Haan, Phys. Fluids B 3, 2349 (1991)]; M. Berning and A. M. Rubenchik, Phys. Fluids 10, 1564 (1998)
Asymptotic behavior of the Rayleigh-Taylor instability.
Duchemin, Laurent; Josserand, Christophe; Clavin, Paul
2005-06-10
We investigate long time numerical simulations of the inviscid Rayleigh-Taylor instability at Atwood number one using a boundary integral method. We are able to attain the asymptotic behavior for the spikes predicted by Clavin and Williams for which we give a simplified demonstration. In particular, we observe that the spike's curvature evolves as t(3), while the overshoot in acceleration shows good agreement with the suggested 1/t(5) law. Moreover, we obtain consistent results for the prefactor coefficients of the asymptotic laws. Eventually we exhibit the self-similar behavior of the interface profile near the spike.
Rayleigh-Taylor instability with complex acceleration history.
Dimonte, Guy; Ramaprabhu, Praveen; Andrews, Malcolm
2007-10-01
Experiments and numerical simulations are performed on the Rayleigh-Taylor instability with a complex acceleration history g(t) consisting of consecutive periods of acceleration, deceleration, and acceleration. The dominant bubbles and spikes that grow in the initial unstable phase are found to be shredded by the trailing structures during the stable deceleration phase. This reduces their diameter at the front and increases the atomic mixing such that the growth during the final unstable acceleration is retarded. The simulations are able to describe the bubble evolution only if broadband initial perturbations are assumed. Such a complex g(t) is useful for validating mix models.
Nonstationary Rayleigh-Taylor instability in supernova ejecta
Ribeyre, X.; Hallo, L.; Tikhonchuk, V. T.; Bouquet, S.; Sanz, J.
2007-11-15
This paper studies the effect of a nonstationary shell acceleration on the development of the Rayleigh-Taylor instability (RTI) in supernovae remnants (SNRs). Two groups of solutions describing acceleration and deceleration phase of the SNR shell are obtained. Using a special transformation (co-moving coordinate frame), an exact dispersion relation for nonstationary RTI is derived. It is shown that compressible and incompressible branches are separated for the spherically symmetric flow and only the former is unstable. The exact analytic solution is compared to a simpler WKB-like analysis and a good agreement is shown, which proves that this analysis can be useful and easily extended to further applications.
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.
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
Pruning to Increase Taylor Dispersion in Physarum polycephalum Networks
NASA Astrophysics Data System (ADS)
Marbach, Sophie; Alim, Karen; Andrew, Natalie; Pringle, Anne; Brenner, Michael P.
2016-10-01
How do the topology and geometry of a tubular network affect the spread of particles within fluid flows? We investigate patterns of effective dispersion in the hierarchical, biological transport network formed by Physarum polycephalum. We demonstrate that a change in topology—pruning in the foraging state—causes a large increase in effective dispersion throughout the network. By comparison, changes in the hierarchy of tube radii result in smaller and more localized differences. Pruned networks capitalize on Taylor dispersion to increase the dispersion capability.
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.
Non-linear characteristics of Rayleigh-Taylor instable perturbations
NASA Astrophysics Data System (ADS)
Fan, Zhengfeng; Luo, Jisheng
2008-04-01
The direct numerical simulation method is adopted to study the non-linear characteristics of Rayleigh-Taylor instable perturbations at the ablation front of a 200 μm planar CH ablation target. In the simulation, the classical electrical thermal conductivity is included, and NND difference scheme is used. The linear growth rates obtained from the simulation agree with the Takabe formula. The amplitude distribution of the density perturbation at the ablation front is obtained for the linear growth case. The non-linear characteristics of Rayleigh-Taylor instable perturbations are analyzed and the numerical results show that the amplitude distributions of the compulsive harmonics are very different from that of the fundamental perturbation. The characteristics of the amplitude distributions of the harmonics and their fast growth explain why spikes occur at the ablation front. The numerical results also show that non-linear effects have relations with the phase differences of double mode initial perturbations, and different phase differences lead to varied spikes.
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
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.
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.
Taylor-Fourier spectra to study fractional order systems
NASA Astrophysics Data System (ADS)
Barbé, Kurt; Lauwers, Lieve; Gonzales Fuentes, Lee
2016-06-01
In measurement science mathematical models are often used as an indirect measurement of physical properties which are mapped to measurands through the mathematical model. Dynamical systems describing a physical process with a dominant diffusion or dispersion phenomenon requires a large dimensional model due to its long memory. Ignoring a dominant difussion or dispersion component acts as a confounder which may introduce a bias in the estimated quantities of interest. For linear systems it has been observed that fractional order models outperform classical rational forms in terms of the number of parameters for the same fitting error. However it is not straightforward to deal with a fractional order system or long memory effects without prior knowledge. Since the parametric modeling of a fractional system is very involved, we put forward the question whether fractional insight can be gathered in a non-parametric way. In this paper we show that classical Fourier basis leading to the frequency response function lacks fractional insight. To circumvent this problem, we introduce a fractional Taylor-Fourier basis to obtain non-parametric insight in the fractional system. This analysis proposes a novel type of spectrum to visualize the spectral content of a fractional system: Taylor-Fourier spectrum. This spectrum is fully measurement driven which can be used as a first to explore the fractional dynamics of a measured diffusion or dispersion system.
[Principles of deformity correction using the Taylor Spatial Frame].
Eidelman, Mark; Chezar, Avraham
2005-02-01
Developed in the fifties, the Ilizarov ring external fixator was first introduced to the West in the eighties of the twentieth century. The technique has become widely accepted for the treatment of a wide variety of limb pathologies including complex fractures, deformity correction and limb lengthening. The Taylor Spatial Frame (TSF) was developed by Charles Taylor in the mid nineties. This system is basically a ring external fixator, drawing on the theoretic foundation from the theory of projected geometry and the mechanical bases from the Stewart platforms. This combination provides a stable external fixation device with an outstanding ability for manipulation of the bone fragments in any given direction, and correction of the most complex deformities. Following the application of the frame, internet-based software will provide an instant treatment plane for the correction of the deformity. This will then be carried out by the patient himself until the achievement of an anatomical reduction of the fracture, lengthening or deformity correction. This combination of a stable external fixation device and the accuracy of the computer based technology, makes the TSF the treatment of choice in the precise correction of limb deformities. This review presents an overview of the theoretical foundation and methods of using the TSF, with an emphasis on the advantages of this system and the capabilities in the correction of skeletal deformities.
Experimental Study of Rayleigh-Taylor Instability Using Paramagnetic Fluids
NASA Astrophysics Data System (ADS)
Tsiklashvili, Vladimer; Likhachev, Oleg; Jacobs, Jeffry
2009-11-01
Experiments that take advantage of the properties of paramagnetic liquids are used to study Rayleigh-Taylor instability. A gravitationally unstable combination of a paramagnetic salt solution and a nonmagnetic solution is initially stabilized by a magnetic field gradient that is produced by the contoured pole-caps of a large electromagnet. Rayleigh-Taylor instability originates with the rapid removal of current from the electromagnet, which results in the heavy liquid falling into the light liquid due to gravity and, thus, mixing with it. The mixing zone is visualized by back-lit photography and is recorded with a digital video camera. For visualization purposes, a blue-green dye is added to the magnetic fluid. The mixing rate of the two liquids is determined from an averaged dye concentration across the mixing layer by means of the Beer-Lambert law. After removal of the suspending magnetic field, the initially flat interface between the two liquids develops a random surface pattern with the dominant length scale well approximated by the fastest growing wavelength in accordance with the viscous linear stability theory. Several combinations of paramagnetic and nonmagnetic solutions have been considered during the course of the research. A functional dependence of the mixing layer growth constant, α, on the properties of the liquids is a primary subject of the present study.
Rayleigh-Taylor mixing with space-dependent acceleration
NASA Astrophysics Data System (ADS)
Abarzhi, Snezhana
2016-11-01
We extend the momentum model to describe Rayleigh-Taylor (RT) mixing driven by a space-dependent acceleration. The acceleration is a power-law function of space coordinate, 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 sub-regimes of self-similar RT mixing - the acceleration-driven Rayleigh-Taylor-type mixing and dissipation-driven Richtymer-Meshkov-type mixing 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 space-dependent acceleration from canonical cases of homogeneous turbulence as well as blast waves with first and second kind self-similarity. The work is supported by the US National Science Foundation.
Rayleigh-Taylor mixing with time-dependent acceleration
NASA Astrophysics Data System (ADS)
Abarzhi, Snezhana
2016-10-01
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. The work is supported by the US National Science Foundation.
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.
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
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 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. PMID:26867803
Effects of microbubbles on Taylor-Couette flow
NASA Astrophysics Data System (ADS)
Tasaka, Yuji; Murai, Yuichi; Watamura, Tomoaki; Takeda, Yasushi
2009-11-01
Effects of micro-bubbles on Taylor-Couette flow has been examined by means of ultrasonic velocity profiling (UVP) for wide range of the Reynolds number, 1 <=Re/Rec<=18, where Rec is the critical Reynolds number for the onset of the primary instability. O(10 μm)-diameter hydrogen bubbles generated by electrolysis of water was dispersed into the fluid layer of water between the vertical, co-axial cylinders. The radius ratio of the cylinders and the aspect ratio are 0.905 and 20, the maximum void fraction estimated by input power for the electrolysis is smaller than 0.1 %. Different flow pattern of the rising bubbles are observed in the spatio-temporal velocity distribution measured by UVP; i.e. free rising and snake-like rising. Axial wavelength of the Taylor vortices show no clear influence of bubbles, but the frequency of the azimuthal traveling wave is reduced by bubbles. Since the number of the traveling waves on the azimuthal plane is the same in the conditions, single phase and with bubbles, the reduction of the frequency means the reduction of the traveling velocity of the wave. Facts to change the traveling velocity, the aspect ratio, the radius ratio, the axial wavelength of the vortices and the number of waves, are no difference on the both cases, therefore, we guess the decrease of the shear rate of the fluid due to micro-bubbles induces this reduction of the traveling speed.
The Inhibition of the Rayleigh-Taylor Instability by Rotation.
Baldwin, Kyle A; Scase, Matthew M; Hill, Richard J A
2015-07-01
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.
Shock, release and Taylor impact of the semicrystalline thermoplastic polytetrafluoroethylene
NASA Astrophysics Data System (ADS)
Bourne, N. K.; Brown, E. N.; Millett, J. C. F.; Gray, G. T.
2008-04-01
The high strain-rate response of polymers is a subject that has gathered interest over recent years due to their increasing engineering importance, particularly in load bearing applications subject to extremes of pressure and strain rate. The current work presents two specific sets of experiments interrogating the effect of dynamic, high-pressure loading in the regime of the phase II to phase III pressure-induced crystalline phase transition in polytetrafluoroethylene (PTFE). These are gas-gun driven plate- and Taylor impact. Together these experiments highlight several effects associated with the dynamic, pressure-induced phase transitions in PTFE. An elevated release wave speed shows evidence of a pressure-induced phase change at a stress commensurate with that observed statically. It is shown that convergence between analytic derivations of release wave speed and the data requires the phase II to III transition to occur. Taylor impact is an integrated test that highlights continuum behavior that has origin in mesoscale response. There is a rapid transition from ductile to brittle behavior observed that occurs at a pressure consistent with this phase transition.
Nonlinear equilibrium states in viscoelastic Taylor-Couette flow
NASA Astrophysics Data System (ADS)
Nicolaou, Laura; Page, Jacob; Zaki, Tamer
2016-11-01
Viscoelastic Taylor-Couette flow exhibits a variety of instabilities, some of which can arise in the absence of inertia altogether. Nonlinear solutions of the equilibrium states are sought, where the distorted mean flow is unchanged and the finite-amplitude instability waves are saturated. A key assumption in the theory is that nonlinearity is restricted to the action of the perturbations on the mean flow. Therefore, the perturbation shape is preserved throughout its growth and saturation, and is specified as a weighted sum of the unstable, linear eigenmodes. At low elasticity, a single unstable mode exists in the form of a stationary Taylor vortex, and the predicted saturated state compares favourably with direct numerical simulation (DNS). DNS reveals that the higher harmonics are an order of magnitude weaker than the fundamental frequency, which substantiates the assumption adopted in the theory. At moderate elasticity, multiple modes become unstable, including axially-travelling elastic rolls and stationary vortices. Equilibrium solutions built from superpositions of these modes explain observations from experiments in the literature over a range of shear rates.
Pattern Dynamics in Taylor Vortex Flow with Double Hourglass Geometry
NASA Astrophysics Data System (ADS)
Wiener, Richard; Olsen, Thomas
2005-11-01
In previous investigations ootnotetextWiener et al., Phys. Rev. E 55, 5489 (1997) & Phys. Rev. Lett. 83, 2340 (1999) we have demonstrated experimentally that Taylor vortex flow in an hourglass geometry undergoes a period-doubling cascade to chaotic pattern dynamics that can be controlled by proportional feedback with small perturbations. The hourglass geometry creates a spatial ramp in the Reynolds number. This results in a region of supercritical vortex flow between regions of subcritical structureless flow that provide the pattern with soft boundaries that allow for persistent dynamics. For a range of reduced Reynolds numbers, the Taylor vortex pattern exhibits persistent dynamics consisting of drifting and stretching vortices punctuated with phase slips. Each phase slip corresponds to the generation of a new vortex pair. We are currently investigating the phase dynamics of Tayor vortex flow with a double hourglass geometry which consists of two regions of supercritical flow in which phase slips occur, separated by a narrow region of subcritical flow. Initial results indicate that at some reduced Reynolds numbers there is synchronization between the vortex dynamics in the two regions, both in the temporal occurrence of the phase slips as well as the drift directions of the vortices.
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
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.
NASA Astrophysics Data System (ADS)
Zhu, Yanli; Chen, Haiqiang
2017-05-01
In this paper, we revisit the issue whether U.S. monetary policy is asymmetric by estimating a forward-looking threshold Taylor rule with quarterly data from 1955 to 2015. In order to capture the potential heterogeneity for regime shift mechanism under different economic conditions, we modify the threshold model by assuming the threshold value as a latent variable following an autoregressive (AR) dynamic process. We use the unemployment rate as the threshold variable and separate the sample into two periods: expansion periods and recession periods. Our findings support that the U.S. monetary policy operations are asymmetric in these two regimes. More precisely, the monetary authority tends to implement an active Taylor rule with a weaker response to the inflation gap (the deviation of inflation from its target) and a stronger response to the output gap (the deviation of output from its potential level) in recession periods. The threshold value, interpreted as the targeted unemployment rate of monetary authorities, exhibits significant time-varying properties, confirming the conjecture that policy makers may adjust their reference point for the unemployment rate accordingly to reflect their attitude on the health of general economy.
NASA Astrophysics Data System (ADS)
Toner, J. D.; Sletten, R. S.; Prentice, M. L.
2012-12-01
Soluble salt accumulations in Taylor Valley, Antarctica, provide a history of paleolakes and the advance of the Ross Sea Ice Sheet (RSIS). We measured soluble salts in 89 soils throughout Taylor Valley in soil-water extractions. In western Taylor Valley, soluble salt accumulations are relatively high and are comprised primarily of Na, Ca, Cl, and SO4. In eastern Taylor Valley, soluble salt accumulations are much lower and are comprised primarily of Na and HCO3. Salt compositions measured in soil-water extractions are highly influenced by the dissolution of sparingly soluble salts (e.g. calcite and gypsum) and cation exchange reactions. Furthermore, during soil-water extractions, Ca from calcite or gypsum dissolution exchanges with exchangeable Na, K, and Mg. These processes can strongly influence both the total salt content measured in soils and ionic ratios. Thus, it is important to consider the effects of these reactions when interpreting soluble salt accumulations measured in soil-water extractions. Calcite dissolution and cation exchange reactions also appear to have a widespread natural occurrence, resulting in the Na-HCO3 compositions of soils, streams, and lakes in eastern Taylor Valley. The soluble salt data supports the hypotheses that a lobe of the RSIS expanded into eastern Taylor Valley and dammed proglacial paleolakes. However, in contrast to previous studies, our findings indicate that the RSIS advanced deeper into Taylor Valley and that paleolakes were less extensive. By comparing soluble salt distributions across Taylor Valley, we conclude that a lobe of the RSIS filled all of eastern Taylor Valley and dammed paleolakes in western Taylor Valley up to 300 m elevation. Following ice retreat, smaller paleolakes formed in both western and eastern Taylor Valley up to about 120 m, with a prominent still stands at 80 m that was controlled by the elevation of a major valley threshold.
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 of...
43 CFR 2091.7-2 - Segregative effect and opening: Taylor Grazing Act.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 43 Public Lands: Interior 2 2011-10-01 2011-10-01 false Segregative effect and opening: Taylor Grazing Act. 2091.7-2 Section 2091.7-2 Public Lands: Interior Regulations Relating to Public Lands... LAWS AND RULES Segregation and Opening of Lands § 2091.7-2 Segregative effect and opening: Taylor...
Limb lengthening combined with deformity correction in children with the Taylor Spatial Frame.
Iobst, Christopher
2010-11-01
It is difficult to replicate the regular rate and rhythm described by Ilizarov while lengthening with the Taylor Spatial Frame. The purpose of the study was to examine whether this breach of Ilizarov's principles has any deleterious effect on the ability of children to make healthy regenerate bone. A retrospective case-control study was performed comparing pediatric patients undergoing primarily lengthening with Taylor Spatial Frame rings and struts, and patients undergoing lengthening with Taylor Spatial Frame rings and Ilizarov clickers. Fifteen patients had primarily lengthening with Taylor Spatial Frame rings and struts, and six patients had lengthening with Taylor Spatial Frame rings and Ilizarov clickers. Statistically, there was no significant difference between the two groups in terms of age, latency, pre-operative bone length percentage, and average length gained. The lengthening index for the strut group (1.79 months/cm) was significantly different from the clicker group (1.33 months/cm) with P=0.012. For a pediatric patient with lower extremity long bone deformities in multiple planes, the Taylor Spatial Frame is an excellent option. However, the surgeon should anticipate a slightly longer duration of treatment with the Taylor Spatial Frame compared to Ilizarov frames and plan his/her fixation accordingly. For the straightforward lengthening of pediatric long bones without significant concomitant deformity, our results indicate that the Ilizarov method appears to be superior to the Taylor Spatial Frame struts and should still be considered the gold standard.
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…
NASA Astrophysics Data System (ADS)
Baykara, N. A.; Gürvit, Ercan
2014-10-01
The application of the Fluctuationlessness theorem to the remainder term of Taylor decomposition on which both sides are integrated has been already worked on. In this work the novelty brought to the previous work is to apply the Fluctuationlessness theorem to the remainder part which, itself also is decomposed in Taylor sense.
Dismissal of a Sociologist: The AAUP Report on Carl C. Taylor.
ERIC Educational Resources Information Center
Larson, Olaf F.; Williams, Robin M., Jr.; Wimberley, Ronald C.
1999-01-01
Examines the dismissal in 1931 of distinguished sociologist Carl C. Taylor after 11 years as an influential faculty member and dean at the State College of Agriculture and Engineering of North Carolina. Reviews the subsequent investigation by the American Association of University Professors. Highlights Taylor's career and contributions at…
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.
Taylor's law and body size in exploited marine ecosystems.
Cohen, Joel E; Plank, Michael J; Law, Richard
2012-12-01
Taylor's law (TL), which states that variance in population density is related to mean density via a power law, and density-mass allometry, which states that mean density is related to body mass via a power law, are two of the most widely observed patterns in ecology. Combining these two laws predicts that the variance in density is related to body mass via a power law (variance-mass allometry). Marine size spectra are known to exhibit density-mass allometry, but variance-mass allometry has not been investigated. We show that variance and body mass in unexploited size spectrum models are related by a power law, and that this leads to TL with an exponent slightly <2. These simulated relationships are disrupted less by balanced harvesting, in which fishing effort is spread across a wide range of body sizes, than by size-at-entry fishing, in which only fish above a certain size may legally be caught.
Numerical study of spherical Taylor-Couette flow
NASA Technical Reports Server (NTRS)
Yang, R.-J.
1989-01-01
A new technique to simulate Taylor vortices in a spherical gap between a rotating inner sphere and a stationary outer one has been developed and tested. Paths leading to zero-, one-, and two-vortex flows are designed heuristically. Fictitious symmetric boundaries near the equator are imposed, and the choice of the location of the fictitious boundaries is determined by either one- or two-vortex flow being stimulated. The imposition of one or two fictitious boundaries during the initial calculation generates the state suitable for one-or two-vortex flow to exist. After removing the fictitious boundaries, the flow settles down into its own attractor. Using this method, the three steady flow modes can be simulated by using a half domain. The technique can converge to desired flows very fast, and its results show excellent agreement with experimental ones.
Rayleigh-Taylor instability in accelerated solid media
NASA Astrophysics Data System (ADS)
Piriz, A. R.; Sun, Y. B.; Tahir, N. A.
2017-01-01
A linear study of the Rayleigh-Taylor instability based on momentum conservation and the consideration of an irrotational velocity field for incompressible perturbations is discussed. The theory allows for a very appealing physical picture and for a relatively simple description of the main features of the instability. As a result, it is suitable for the study of the very complex problem of the instability of accelerated solids with non-linear elastic-plastic constitutive properties, which cannot be studied by the usual normal modes approach. The elastic to plastic transition occurring early in the instability process determines the entire evolution and makes the instability exhibit behavior that cannot be captured by an asymptotic analysis.
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].
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.
Rayleigh-Taylor stabilization by material strength at Mbar pressures
NASA Astrophysics Data System (ADS)
Remington, Bruce; Park, Hye-Sook; Lorenz, Thomas; Cavallo, Robert; Pollaine, Stephen; Prisbrey, Shon; Rudd, Robert; Becker, Richard; Bernier, Joel
2009-11-01
We present experiments on the Rayleigh-Taylor (RT) instability in the plastic flow regime of solid-state vanadium (V) foils at 1 Mbar pressures and strain rates of 1.e6-1.e8 1/s, using a laser based, ramped-pressure acceleration technique. High pressure material strength causes strong stabilization of the RT instability at short wavelengths. Comparisons with 2D simulations utilizing models of high pressure strength show that the V strength increases by factors of 3-4 at peak pressure, compared to its ambient strength. An effective lattice viscosity of 400 poise would have a similar effect. [1] Constitutive models, and theoretical implications of these experiments will be discussed. [1] H.S. Park, B.A. Remington et al., submitted for publication (July, 2009).
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.
Taylor's law and body size in exploited marine ecosystems
Cohen, Joel E; Plank, Michael J; Law, Richard
2012-01-01
Taylor's law (TL), which states that variance in population density is related to mean density via a power law, and density-mass allometry, which states that mean density is related to body mass via a power law, are two of the most widely observed patterns in ecology. Combining these two laws predicts that the variance in density is related to body mass via a power law (variance-mass allometry). Marine size spectra are known to exhibit density-mass allometry, but variance-mass allometry has not been investigated. We show that variance and body mass in unexploited size spectrum models are related by a power law, and that this leads to TL with an exponent slightly <2. These simulated relationships are disrupted less by balanced harvesting, in which fishing effort is spread across a wide range of body sizes, than by size-at-entry fishing, in which only fish above a certain size may legally be caught. PMID:23301181
Charge-Induced Saffman-Taylor Instabilities in Toroidal Droplets
NASA Astrophysics Data System (ADS)
Fragkopoulos, A. A.; Aizenman, A.; Fernández-Nieves, A.
2017-06-01
We show that charged toroidal droplets can develop fingerlike structures as they expand due to Saffman-Taylor instabilities. While these are commonly observed in quasi-two-dimensional geometries when a fluid displaces another fluid of higher viscosity, we show that the toroidal confinement breaks the symmetry of the problem, effectively making it quasi-two-dimensional and enabling the instability to develop in this three-dimensional situation. We control the expansion speed of the torus with the imposed electric stress and show that fingers are observed provided the characteristic time scale associated with this instability is smaller than the characteristic time scale associated with Rayleigh-Plateau break-up. We confirm our interpretation of the results by showing that the number of fingers is consistent with expectations from linear stability analysis in radial Hele-Shaw cells.
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"
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.
Linear analysis of incompressible Rayleigh-Taylor instability in solids
NASA Astrophysics Data System (ADS)
Piriz, A. R.; López Cela, J. J.; 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.
Rayleigh-Taylor instability in soft elastic layers
NASA Astrophysics Data System (ADS)
Riccobelli, D.; Ciarletta, P.
2017-04-01
This work investigates the morphological stability of a soft body composed of two heavy elastic layers attached to a rigid surface and subjected only to the bulk gravity force. Using theoretical and computational tools, we characterize the selection of different patterns as well as their nonlinear evolution, unveiling the interplay between elastic and geometric effects for their formation. Unlike similar gravity-induced shape transitions in fluids, such as the Rayleigh-Taylor instability, we prove that the nonlinear elastic effects saturate the dynamic instability of the bifurcated solutions, displaying a rich morphological diagram where both digitations and stable wrinkling can emerge. The results of this work provide important guidelines for the design of novel soft systems with tunable shapes, with several applications in engineering sciences. This article is part of the themed issue 'Patterning through instabilities in complex media: theory and applications.'
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.
Size invariance of the granular Rayleigh-Taylor instability.
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 approximately 70 microm or greater than approximately 570 microm in diameter.
Experiments of periodic forcing of Saffman-Taylor fingers
NASA Astrophysics Data System (ADS)
Torralba, M.; Ortín, J.; Hernández-Machado, A.; Poiré, E. Corvera
2008-03-01
We report on an experimental study of long normal Saffman-Taylor fingers subject to periodic forcing. The sides of the finger develop a low amplitude, long wavelength instability. We discuss the finger response in stationary and nonstationary situations, as well as the dynamics towards the stationary states. The response frequency of the instability increases with forcing frequency at low forcing frequencies, while, remarkably, it becomes independent of forcing frequency at large forcing frequencies. This implies a process of wavelength selection. These observations are in good agreement with previous numerical results reported in [Ledesma-Aguilar , Phys. Rev. E 71, 016312 (2005)]. We also study the average value of the finger width, and its fluctuations, as a function of forcing frequency. The average finger width is always smaller than the width of the steady-state finger. Fluctuations have a nonmonotonic behavior with a maximum at a particular frequency.
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.
Numerical study of spherical Taylor-Couette flow
NASA Technical Reports Server (NTRS)
Yang, R.-J.
1989-01-01
A new technique to simulate Taylor vortices in a spherical gap between a rotating inner sphere and a stationary outer one has been developed and tested. Paths leading to zero-, one-, and two-vortex flows are designed heuristically. Fictitious symmetric boundaries near the equator are imposed, and the choice of the location of the fictitious boundaries is determined by either one- or two-vortex flow being stimulated. The imposition of one or two fictitious boundaries during the initial calculation generates the state suitable for one-or two-vortex flow to exist. After removing the fictitious boundaries, the flow settles down into its own attractor. Using this method, the three steady flow modes can be simulated by using a half domain. The technique can converge to desired flows very fast, and its results show excellent agreement with experimental ones.
The magnetic Rayleigh-Taylor instability in astrophysical discs
NASA Astrophysics Data System (ADS)
Contopoulos, I.; Kazanas, D.; Papadopoulos, D. B.
2016-10-01
This is our first study of the magnetic Rayleigh-Taylor instability at the inner edge of an astrophysical disc around a central back hole. We derive the equations governing small-amplitude oscillations in general relativistic ideal magnetodydrodynamics and obtain a criterion for the onset of the instability. We suggest that static disc configurations where magnetic field is held by the disc material are unstable around a Schwarzschild black hole. On the other hand, we find that such configurations are stabilized by the space-time rotation around a Kerr black hole. We obtain a crude estimate of the maximum amount of poloidal magnetic flux that can be accumulated around the centre, and suggest that it is proportional to the black hole spin. Finally, we discuss the astrophysical implications of our result for the theoretical and observational estimations of the black hole jet power.
Lattice QCD at finite temperature and density from Taylor expansion
NASA Astrophysics Data System (ADS)
Steinbrecher, Patrick
2017-01-01
In the first part, I present an overview of recent Lattice QCD simulations at finite temperature and density. In particular, we discuss fluctuations of conserved charges: baryon number, electric charge and strangeness. These can be obtained from Taylor expanding the QCD pressure as a function of corresponding chemical potentials. Our simulations were performed using quark masses corresponding to physical pion mass of about 140 MeV and allow a direct comparison to experimental data from ultra-relativistic heavy ion beams at hadron colliders such as the Relativistic Heavy Ion Collider at Brookhaven National Laboratory and the Large Hadron Collider at CERN. In the second part, we discuss computational challenges for current and future exascale Lattice simulations with a focus on new silicon developments from Intel and NVIDIA.
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.
The Magnetic Rayleigh-Taylor Instability in Astrophysical Discs
NASA Technical Reports Server (NTRS)
Contopoulos, I.; Kazanas, D.; Papadopoulos, D. B.
2016-01-01
This is our first study of the magnetic Rayleigh-Taylor instability at the inner edge of an astrophysical disc around a central back hole. We derive the equations governing small-amplitude oscillations in general relativistic ideal magnetodydrodynamics and obtain a criterion for the onset of the instability. We suggest that static disc configurations where magnetic field is held by the disc material are unstable around a Schwarzschild black hole. On the other hand, we find that such configurations are stabilized by the space-time rotation around a Kerr black hole. We obtain a crude estimate of the maximum amount of poloidal magnetic flux that can be accumulated around the centre, and suggest that it is proportional to the black hole spin. Finally, we discuss the astrophysical implications of our result for the theoretical and observational estimations of the black hole jet power.
Bubble acceleration in the ablative Rayleigh-Taylor instability.
Betti, R; Sanz, J
2006-11-17
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 and vorticity convection off the ablation front. While the ablative 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.
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.
Rayleigh-Taylor stability boundary at solid-liquid interfaces.
Piriz, A R; Sun, Y B; Tahir, N A
2013-08-01
A previous model for the Rayleigh-Taylor instability [A. R. Piriz, J. J. López Cela, and N. A. Tahir, Phys. Rev. E 80, 046305 (2009)] has been extended in order to study an interface between an elastic-plastic solid and a Newtonian liquid and determine the stability region given by the initial perturbation amplitude ξ(0) and wavelength λ. The stability region is found to be enhanced by the effect of the liquid viscosity, but it reaches an asymptote for a sufficiently high viscosity. In addition, it is also found that the boundary for the transition from the elastic to the plastic regime get closer to the stability boundary up to both boundaries coincide for a high enough liquid viscosity, thus making the onset of plastic flow a sufficient condition for instability.
Viscous Rayleigh-Taylor instability in spherical geometry.
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)] 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)].
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.
Kolmogorov scaling and intermittency in Rayleigh-Taylor turbulence.
Boffetta, G; Mazzino, A; Musacchio, S; Vozella, L
2009-06-01
Turbulence induced by Rayleigh-Taylor instability is a ubiquitous phenomenon with applications ranging from atmospheric physics and geophysics to supernova explosions and plasma confinement fusion. Despite its fundamental character, a phenomenological theory has been proposed only recently and several predictions are untested. In this Rapid Communication we confirm spatiotemporal predictions of the theory by means of direct numerical simulations at high resolution and we extend the phenomenology to take into account intermittency effects. We show that scaling exponents are indistinguishable from those of Navier-Stokes turbulence at comparable Reynolds number, a result in support of the universality of turbulence with respect to the forcing mechanism. We also show that the time dependence of Rayleigh, Reynolds, and Nusselt numbers realizes the Kraichnan scaling regime associated with the ultimate state of thermal convection.
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.
Modified formula of Malus’ law for Glan Taylor polarizing prisms
NASA Astrophysics Data System (ADS)
Zhu, Huafeng; Song, Lianke; Chen, Jianwen; Gao, Hongyi; Li, Ruxin; Xu, Zhizhan
2005-01-01
A simple three-axis model has been developed, which has been successfully applied to the analysis of the light transmittance in spatial incident angle and the simulation of modified formula of Malus' law for Glan-Taylor prisms. Our results indicate that the fluctuations on the cosine squared curve are due to specific misalignments between the axis of the optical system, the optical axis of the prism and the mechanical axis (rotation axis) of prism, which results in the fact that different initial relative location of the to-be-measured-prism in the testing system corresponds to different shape of Malus' law curve. Methods to get absolutely smooth curve are proposed. This analysis is available for other kinds of Glan-type prisms.
Nonlinear Rayleigh-Taylor growth in convergine geometry
Clark, D S; Tabak, M
2004-04-26
The early nonlinear phase of Rayleigh-Taylor growth is typically described in terms of the classic Layzer model in which bubbles of light fluid rise into the heavy fluid at a constant rate determined by the bubble radius and the gravitational acceleration. However, this model is strictly valid only for planar interfaces and hence ignores any effects which might be introduced by the spherically converging interfaces of interest in inertial confinement fusion. Here a generalization of the Layzer nonlinear bubble rise rate is given for a self-similar spherically converging flow of the type studied by Kidder. A simple formula for the bubble amplitude is found showing that, while the bubble initially rises with a constant velocity similar to the Layzer result, during the late phase of the implosion, an acceleration of the bubble rise rate occurs. The bubble rise rate is verified by comparison with numerical hydrodynamics simulations.
Simulations of NOVA direct-drive Rayleigh-Taylor experiments
Weber, S.V.
1990-11-03
Directly driven Rayleigh-Taylor instability growth experiments being performed on NOVA have been simulated using the computer code, LASNEX. These experiments employ beams smoothed with random phase plates (RPP), and will later include smoothing by spectral dispersion (SSD). Samples are CH foils with or without imposed sinusoidal surface perturbations. Perturbation growth is diagnosed by means of x-ray backlighting. Calculated growth rates are fairly flat across the wavelength range of 20--80 {mu}m which can be accessed experimentally, and are moderately suppressed below classical growth rates. Perturbations of large enough initial amplitude that the contrast in the x-ray image is measurable from the start of the experiment quickly grow into the nonlinear regime. Smaller initial amplitudes result in a longer interval of linear growth, but the initial perturbation will not be detectable in the data. Structure which is predicted to develop from speckles in the RPP beam pattern, with and without SSD, is also presented.
Vortical Effects on the Compressible Rayleigh-Taylor Instability
NASA Astrophysics Data System (ADS)
Wieland, Scott; Livescu, Daniel; Vasilyev, Oleg V.; Reckinger, Scott J.
2016-11-01
High fidelity wavelet based direct numerical simulations (WDNS) of compressible, miscible, and single mode Rayleigh Taylor instability (RTI) with a stratified background density have been completed in 2 and 3 dimensions. As the instability grows, vorticity dynamics are largely responsible for the self-propagation and growth of the bubble and spike. However, in the presence of a background stratification, the vortex interactions are significantly altered. In the case of low Atwood number RTI, this leads to previously unseen regimes, namely, the exaggeration of bubble and spike asymmetries for a weakly stratified background state and the complete suppression of RTI growth in the strongly stratified scenario. To better understand these results, the vorticity transport equation budget was compared to the simplified scenarios of vortex pairs (2D) and vortex rings (3D) moving in a stratified medium.
Magnetic Shear, Rayleigh-Taylor Instability, And Prominence Threads
NASA Astrophysics Data System (ADS)
DeVore, C. Richard
2012-05-01
One striking feature of solar prominences is their very long, narrow threads of cool plasma that are observed in emission above the limb (and in absorption against the disk in filaments). It is generally accepted that this structure illuminates the prominence magnetic field, which both mechanical supports the cool mass against gravity and thermally insulates it against conduction from the surrounding hot corona. A mystery yet to be resolved is the origin of the narrow widths of prominence threads. We are investigating the hypothesis that it is fixed by a competition between the gravitational instability of a dense fluid (the prominence) residing above a dilute fluid (the corona) and the stabilizing influence of magnetic tension forces when the prominence field is distorted. It is well known (e.g., Stone & Gardiner 2007) that this process leads to the formation of ropes of dense fluid whose characteristic lengths are long parallel to the field (minimizing the increase in magnetic energy) but arbitrarily short perpendicular to the field (maximizing the release of gravitational energy). A key issue that has yet to be addressed is the effect on the Rayleigh-Taylor instability of shear in a magnetic field whose direction rotates continuously through the body of the prominence. Linear analysis indicates that marginal stability is reached for aspect ratios (parallel to perpendicular wavelengths) of about 25:1 for solar parameters; unstable modes have still larger ratios. High-resolution numerical simulations of initially monolithic slab prominences show developing fragmentation of the prominence/corona interface driven by the early, linear growth of the shear-modified Rayleigh-Taylor instability. Our investigation also is probing the nonlinear consequences of this evolution. This work was supported by NASA’s LWS TR&T program.
DSMC Simulation of High Mach Number Taylor-Couette Flow
NASA Astrophysics Data System (ADS)
Pradhan, Sahadev, , Dr.
2017-01-01
The main focus of this work is to characterise the Taylor-Couette flow of an ideal gas between two coaxial cylinders at Mach number Ma = (U_w /√{ kbT_w / m }) in the range 0.01 < Ma < 10, and Knudsen number Kn = (1 / (√{ 2 } πd2 n_d (r _ 2 - r _ 1))) in the range 0.001
Unstable Titan-generated Rayleigh-Taylor Lakes Impact Ice
NASA Astrophysics Data System (ADS)
Umurhan, O. M.; Korycansky, D. G.; Zahnle, K. J.
2014-12-01
The evolution of surface morphology on Titan, Triton, and other worlds is strongly influenced by the interplay of various fluid dynamical processes. Specifically, overturning instabilities can easily arise due to the special circumstances of landform evolution that probably occurred on these worlds. On Titan, large impacts that formed basins like Menrva crater (and possibly Hotei Regio) would have generated impact-melt ice lakes unstably arranged over less dense ice. Cantaloupe terrains, for example as seen on Triton, may be the result of condensation of volatiles (methane, nitrogen) leading to unstably stratified layers of different compositions and densities. In each of these cases, Rayleigh-Taylor instabilities leading to large scale diapirism may be at play. In addition to the dynamics of these instabilities, other physical effects (e.g. heat diffusion, freezing/melting, porosity, temperature dependent viscosity) likely play an important role in the evolution of these features. In this ongoing study, we examine the properties of unstably stratified fluids in which the lower less-dense ice has a temperature dependent viscosity. Surprisingly, we find that there exists an optimal disturbance length scale corresponding to the fastest growth of the Rayleigh-Taylor instability. For unstably stratified layers of water (low viscosity heavy liquid lying above an ice whose viscosity increases with depth) the fastest growing mode corresponds to 40-60 km scales with overturn times of approximately 100 days. We present a detailed numerical stability analysis in a corresponding Boussinessq model (in the creeping flow limit) incorporating thermal conduction and latent heat release and we examine the stability properties surveying a variety of parameters. We have also developed a two-dimensional numerical code (a hybrid spectral/compact-differencing scheme) to model the evolution of such systems for which we shall present preliminary numerical results depicting the outcome of
Federal Register 2010, 2011, 2012, 2013, 2014
2010-07-21
... Liberian Regime of Charles Taylor On July 22, 2004, by Executive Order 13348, the President declared a... connected to the former Liberian regime of Charles Taylor, pursuant to the International Emergency Economic... former Liberian President Charles Taylor and other persons, in particular their unlawful depletion...
Federal Register 2010, 2011, 2012, 2013, 2014
2011-07-21
... With Respect to the Former Liberian Regime of Charles Taylor #0; #0; #0; Presidential Documents #0; #0... Respect to the Former Liberian Regime of Charles Taylor On July 22, 2004, by Executive Order 13348, the... of certain persons connected to the former Liberian regime of Charles Taylor, pursuant to...
Federal Register 2010, 2011, 2012, 2013, 2014
2013-07-19
... Liberian Regime of Charles Taylor On July 22, 2004, by Executive Order 13348, the President declared a national emergency with respect to the former Liberian regime of Charles Taylor pursuant to the... Liberian President Charles Taylor and other persons, in particular their unlawful depletion of...
77 FR 48150 - Carolina Gas Transmission Corporation; Notice of Request Under Blanket Authorization
Federal Register 2010, 2011, 2012, 2013, 2014
2012-08-13
... sections 157.205 and 157.210 of the Commission's Regulations under the Natural Gas Act (NGA) as amended, to... Energy Regulatory Commission Carolina Gas Transmission Corporation; Notice of Request Under Blanket Authorization Take notice that on July 25, Carolina Gas Transmission Corporation (Carolina Gas), 601 Old Taylor...
García Casado, Gustavo; Tofaletti, Lorena; Müller, Darío; D'Onofrio, Alejandro
2007-03-21
The influence of temperature in the buoyancy driven Rayleigh-Taylor instability of reaction-diffusion fronts is investigated experimentally in Hele-Shaw cells. The acid autocatalysis of chlorite-tetrathionate reaction coupled to molecular diffusion yields exothermic planar reaction-diffusion fronts separating two miscible reactant and product solutions. The resulting chemical front moves downwards invading the fresh reactants, leaving the products of the reaction behind it. The density of the product solution is higher than the reactant solution; hence, the traveling front is buoyantly unstable and develops density fingers in time (Rayleigh-Taylor instability) when the products are above the reactants. The kinetic constant of a chemical reaction varies due to thermal effects. This may stabilize the exothermic descending front when temperature is increased, so that the mixing zone decreases, modifying the fingering patterns, until it almost disappears. The authors study the influence of the temperature variation on the instability pattern figure observed in the chlorite-tetrathionate reaction for long times, corresponding to the nonlinear regime.
NASA Astrophysics Data System (ADS)
García Casado, Gustavo; Tofaletti, Lorena; Müller, Darío; D'Onofrio, Alejandro
2007-03-01
The influence of temperature in the buoyancy driven Rayleigh-Taylor instability of reaction-diffusion fronts is investigated experimentally in Hele-Shaw cells. The acid autocatalysis of chlorite-tetrathionate reaction coupled to molecular diffusion yields exothermic planar reaction-diffusion fronts separating two miscible reactant and product solutions. The resulting chemical front moves downwards invading the fresh reactants, leaving the products of the reaction behind it. The density of the product solution is higher than the reactant solution; hence, the traveling front is buoyantly unstable and develops density fingers in time (Rayleigh-Taylor instability) when the products are above the reactants. The kinetic constant of a chemical reaction varies due to thermal effects. This may stabilize the exothermic descending front when temperature is increased, so that the mixing zone decreases, modifying the fingering patterns, until it almost disappears. The authors study the influence of the temperature variation on the instability pattern figure observed in the chlorite-tetrathionate reaction for long times, corresponding to the nonlinear regime.
A study of thin-walled Taylor column under the influence of rotation
NASA Astrophysics Data System (ADS)
Lai, Kuan-Ruei; Chu, Chin-Chou; Chang, Chien-Cheng
2016-11-01
An extended study of thin-walled Taylor column under the influence of rotating cylinder is presented with very consistent results in numerical simulations and laboratory experiments. In the previous set-up, the Taylor column effect is produced under the influence of protruded cylinder from the top lid, and the thin-walled Taylor column is formed by draining of the fluid at the bottom. The primary interest of this study is to investigate the influence to thin-walled Taylor column when the cylinder is exerted with a relative rotation rate under very small Rossby number (Ro = U / fR) and Ekman number (Ek = ν / fR2) . The flow patterns are performed with different cylinder height ratios (h/ H) along with varying relative rotation ratio of cylinder to the background α = ω / Ω . Steady-state solutions being solved numerically in the rotating frame are shown to have good agreements with experimental flow visualizations on the resulting appearance of deformed thin-walled Taylor columns. As a result, the thin-walled Taylor column is observed to strengthen up with increasing α, and weakens with decreasing α. In addition, the weakening thin-walled Taylor column is observed to experience a break through transition near the bottom, which penetration diverged the recirculating region into two portions. Supported by the Ministry of Science and Technology, TAIWAN ROC, Contract No's 103-2221-E002-099-MY3; 105-2221-E002-097-MY3.
Competing states in a Couette-Taylor system with an axial flow
NASA Astrophysics Data System (ADS)
Tsameret, Avraham; Steinberg, Victor
1994-05-01
We present experimental results on novel pattern states which were observed in the Couette-Taylor flow subjected to an axial flow, in a wide range of the control parameters. Propagating Taylor vortices (PTV's), stationary spirals (SSP's), and moving spirals (MS's) were found as a result of a different symmetry breaking. These modes exhibit different wave-number selection. Novel states originating from an interaction between these patterns were also found. A ``mixed phase'' of PTV's and SSP's was identified. A ``mode-competition'' state, in which the PTV's and MS's are alternated in the column, is also described. Finally, a ``disordered-Taylor-vortices'' state was observed and characterized.
Quantum effects on the Rayleigh-Taylor instability in a horizontal inhomogeneous rotating plasma
Hoshoudy, G. A.
2009-06-15
The Rayleigh-Taylor instability is studied analytically in inhomogeneous plasma rotating uniformly in an external transverse magnetic field. The influence of the quantum mechanism is considered. For a stratified layer the linear growth rate is obtained. Some special cases that isolate the effect of various parameters on the growth rate of the Rayleigh-Taylor instability are discussed. It is shown that for some cases, the presence of the external transverse magnetic field beside the quantum effect will bring about more stability on the Rayleigh-Taylor instability.
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
A qualitative study of a nanotube model using an iterative Taylor method
NASA Astrophysics Data System (ADS)
Gadella, M.; Lara, L. P.; Negro, J.
Physical properties of graphene nanotubes may strongly depend on external fields. In a recent paper V. Jakubský, S. Kuru, J. Negro, J. Phys. A: Math. Theor. 47, 115307 (2014), the authors have studied a model of carbon nanotubes under the presence of an external magnetic field, chosen for some symmetry properties. The model admits an exact solution, provided that the value of a parameter, here denoted as kz, be equal to zero. This parameter is the eigenvalue of the component of the momentum in the direction of the nanotube axis. However, it seems that this parameter cannot be discarded for physical reasons. The choice of nontrivial values for this parameter produces an equation of motion for electrons in the nanotube (a Dirac-Weyl equation), which cannot be exactly solvable. Then, we proposed some iterative approximate methods to solve this equation and obtaining its eigenvalues. Some tests have shown that an iterative Taylor method is more efficient than some others we have used. For kz≠0, we have found that, excluding the minimal energy eigenvalue, the lowest energy values obtained for kz=0 split into two different ones and, therefore, producing gaps in the energy spectrum.
Exploring elastic and plastic regimes of Rayleigh-Taylor instability in solids
NASA Astrophysics Data System (ADS)
Polavarapu, Rinosh; Banerjee, Arindam
2014-11-01
The elastic-plastic (EP) transition stage of Rayleigh-Taylor (RT) instability was studied in an accelerated elastic-plastic solid. A novel rotating wheel RT experiment with linear vibratory motion that centrifugally accelerates a test section with two-material interface was utilized. The test section consists of a container filled with air and mayonnaise, a non-Newtonian emulsion, with an initial perturbation between the two materials. Single mode perturbations of various amplitudes and wavelengths were analyzed earlier to find the effects of initial conditions on instability acceleration. Presently, the EP transition process for a stable interface before reaching the instability was verified by accelerating the test section to a magnitude which is slightly less than critical acceleration and imparting linear vibration which alters the radius of circular path and thus varies the magnitude of centrifugal force. The results were compared with various instability and EP transition criteria given by analytical growth models. The authors acknowledge support of the DOE-SSAP (Grant # DE-NA0001975) and DOE-LANL subcontract (Grant #173-667-1).
Effects of Initial Conditions on Rayleigh-Taylor Instability in Elastic-Plastic Materials
NASA Astrophysics Data System (ADS)
Roach, Pamela; Banerjee, Arindam
2012-11-01
In contrast to Newtonian fluids, experimental study of Rayleigh Taylor instability (RTI) in accelerated solids is traditionally hindered by difficulty to measure material properties and exceedingly small time scales of the processes. When an elastic-plastic solid is accelerated due to a density gradient, the instability is dependent on the material's mechanical strength, initial conditions, and acceleration that drive the instability. RTI in solids is observed in supernovas, explosive welding, and inertial confinement fusion. A novel experimental technique is used to study the effects of initial conditions and variable accelerations on the growth and instability in an elastic-plastic solid. The experiment consists of a container filled with air and mayonnaise, a non-Newtonian emulsion, with an initial perturbation between the two materials. Single mode perturbations of various amplitudes are analyzed and effects of two-dimensional versus three-dimensional interfaces are discussed. Furthermore, the instability threshold and stable elastic and plastic regions are investigated by controlling the acceleration. The instability threshold and perturbation growth rate are compared to linear analysis of incompressible RTI. The authors acknowledge financial support through DOE-LANL subcontract # 173667-1.
Effects of acceleration rate on Rayleigh-Taylor instability in elastic-plastic materials
NASA Astrophysics Data System (ADS)
Banerjee, Arindam; Polavarapu, Rinosh
2016-11-01
The effect of acceleration rate in the elastic-plastic transition stage of Rayleigh-Taylor instability in an accelerated non-Newtonian material is investigated experimentally using a rotating wheel experiment. A non-Newtonian material (mayonnaise) was accelerated at different rates by varying the angular acceleration of a rotating wheel and growth patterns of single mode perturbations with different combinations of amplitude and wavelength were analyzed. Experiments were run at two different acceleration rates to compare with experiments presented in prior years at APS DFD meetings and the peak amplitude responses are captured using a high-speed camera. Similar to the instability acceleration, the elastic-plastic transition acceleration is found to be increasing with increase in acceleration rate for a given amplitude and wavelength. The experimental results will be compared to various analytical strength models and prior experimental studies using Newtonian fluids. Authors acknowledge funding support from Los Alamos National Lab subcontract(370333) and DOE-SSAA Grant (DE-NA0001975).
Experiments on Effects of Initial Conditions and Material Strength on Rayleigh-Taylor Instability
NASA Astrophysics Data System (ADS)
Roach, Pamela; Banerjee, Arindam
2013-11-01
The effects of initial conditions on Rayleigh-Taylor (RT) instability in an accelerated elastic-plastic solid were studied. A novel rotating wheel RT experiment that uses centrifugal forces to accelerate a two-material interface was utilized to study the effect of amplitude and wavelength on RT instability with an elastic-plastic solid. The experiment consists of a container filled with air and mayonnaise, a non-Newtonian emulsion, with an initial perturbation between the two materials. Single mode perturbations of various amplitudes and wavelengths were analyzed and results indicated the acceleration required for instability increased for both decreasing initial amplitude and wavelength. Three-dimensional interfaces were found to be more stable than two-dimensional interfaces. Critical amplitude and growth rates were compared with prior experimental results and analytical growth models. Elastic and plastic peak amplitude responses were observed for stable interfaces using a variable acceleration profile where the test section was first accelerated to slightly below the critical acceleration and then decelerated at the same rate. This exercise allowed for verification of the elastic-plastic (EP) transition process before instability was reached. Authors acknowledge financial support from DOE-LANL subcontract # 173667-1 to Lehigh University and a NSF-Graduate Research Fellowship to Pamela Roach.
Rayleigh-Taylor Gravity Waves and Quasiperiodic Oscillation Phenomenon in X-ray Binaries
NASA Technical Reports Server (NTRS)
Titarchuk, Lev
2002-01-01
Accretion onto compact objects in X-ray binaries (black hole, neutron star (NS), white dwarf) is characterized by non-uniform flow density profiles. Such an effect of heterogeneity in presence of gravitational forces and pressure gradients exhibits Rayleigh-Taylor gravity waves (RTGW). They should be seen as quasiperiodic wave oscillations (QPO) of the accretion flow in the transition (boundary) layer between the Keplerian disk and the central object. In this paper the author shows that the main QPO frequency, which is very close to the Keplerian frequency, is split into separate frequencies (hybrid and low branch) under the influence of the gravitational forces in the rotational frame of reference. The RTGWs must be present and the related QPOs should be detected in any system where the gravity, buoyancy and Coriolis force effects cannot be excluded (even in the Earth and solar environments). The observed low and high QPO frequencies are an intrinsic signature of the RTGW. The author elaborates the conditions for the density profile when the RTGW oscillations are stable. A comparison of the inferred QPO frequencies with QPO observations is presented. The author finds that hectohertz frequencies detected from NS binaries can be identified as the RTGW low branch frequencies. The author also predicts that an observer can see the double NS spin frequency during the NS long (super) burst events when the pressure gradients and buoyant forces are suppressed. The Coriolis force is the only force which acts in the rotational frame of reference and its presence causes perfect coherent pulsations with a frequency twice of the NS spin. The QPO observations of neutron binaries have established that the high QPO frequencies do not go beyond of the certain upper limit. The author explains this observational effect as a result of the density profile inversions. Also the author demonstrates that a particular problem of the gravity waves in the rotational frame of reference in the
Ablation front rayleigh taylor dispersion curve in indirect drive
Budil, K S; Lasinski, B; Edwards, M J; Wan, A S; Remington, B A; Weber, S V; Glendinning, S G; Suter, L; Stry, P
2000-11-17
The Rayleigh-Taylor (RT) instability, which occurs when a lower-density fluid accelerates a higher-density layer, is common in nature. At an ablation front a sharp reduction in the growth rate of the instability at short wave-lengths can occur, in marked contrast to the classical case where growth rates are highest at the shortest wavelengths. Theoretical and numerical investigations of the ablative RT instability are numerous and differ considerably on the level of stabilization expected. We present here the results of a series of laser experiments designed to probe the roll-over and cutoff region of the ablation-front RT dispersion curve in indirect drive. Aluminum foils with imposed sinusoidal perturbations ranging in wavelength from 10 to 70 pm were ablatively accelerated with a radiation drive generated in a gold cylindrical hohlraum. A strong shock wave compresses the package followed by an {approx}2 ns period of roughly constant acceleration and the experiment is diagnosed via face-on radiography. Perturbations with wavelengths {ge} 20 {micro}m experienced substantial growth during the acceleration phase while shorter wavelengths showed a sharp drop off in overall growth. These experimental results compared favorably to calculations with a 2-D radiation-hydrodynamics code, however, the growth is significantly affected by the rippled shock launched by the drive. We performed numerical simulations to elucidate the influence of the rippled shock wave on the eventual growth of the perturbations, allowing comparisons to the analytic model developed by Betti et al. This combination of experiments, simulations and analytic modeling illustrates the qualitative simplicity yet quantitative complexity of the compressible RT instability. We have measured the Rayleigh-Taylor (RT) dispersion curve for a radiatively-driven sample in a series of experiments on the Nova laser facility. Planar aluminum foils were ablatively-accelerated and the subsequent perturbation growth
Employing Taylor and Heisenberg subfilter viscosities to simulate turbulent statistics in LES models
NASA Astrophysics Data System (ADS)
Degrazia, G. A.; Rizza, U.; Puhales, F. S.; Welter, G. S.; Acevedo, O. C.; Maldaner, S.
2012-02-01
A turbulent subfilter viscosity for Large Eddy Simulation (LES) based on the Taylor statistical diffusion theory is proposed. This viscosity is described in terms of a velocity variance and a time scale, both associated to the inertial subrange. This new subfilter viscosity contains a cutoff wavenumber kc, presenting an identical form (differing by a constant) to the Heisenberg subfilter viscosity. Therefore, both subfilter viscosities are described in terms of a sharp division between large and small wavenumbers of a turbulent flow and, henceforth, Taylor and Heisenberg subfilter viscosities are in agreement with the sharp Fourier filtering operation, frequently employed in LES models. Turbulent statistics of different orders, generated from atmospheric boundary layer simulations employing both Taylor and Heisenberg subfilter viscosities have been compared with observations and results provided by other simulations. The comparison shows that the LES model utilizing the approaches of Taylor and Heisenberg reproduces these turbulent statistics correctly in different vertical regions of a planetary convective boundary layer (CBL).
Rayleigh-Taylor mixing: direct numerical simulation and implicit large eddy simulation
NASA Astrophysics Data System (ADS)
Youngs, David L.
2017-07-01
Previous research into three-dimensional numerical simulation of self-similar mixing due to Rayleigh-Taylor instability is summarized. A range of numerical approaches has been used: direct numerical simulation, implicit large eddy simulation and large eddy simulation with an explicit model for sub-grid-scale dissipation. However, few papers have made direct comparisons between the various approaches. The main purpose of the current paper is to give comparisons of direct numerical simulations and implicit large eddy simulations using the same computational framework. Results are shown for four test cases: (i) single-mode Rayleigh-Taylor instability, (ii) self-similar Rayleigh-Taylor mixing, (iii) three-layer mixing and (iv) a tilted-rig Rayleigh-Taylor experiment. It is found that both approaches give similar results for the high-Reynolds number behavior. Direct numerical simulation is needed to assess the influence of finite Reynolds number.
Analytical solution of the problem of the rise of a Taylor bubble
NASA Astrophysics Data System (ADS)
Zudin, Yuri B.
2013-05-01
In the classical works of Prandtl and Taylor devoted to the analysis of the problem of the rise of a Taylor bubble in a round tube, a solution of the Laplace equation is used, which contains divergent infinite series. The present paper outlines a method for the correct analysis of the mentioned problem. Using the method of superposition of "elementary flows," a solution was obtained for flow of an ideal fluid over a body of revolution in a pipe. Satisfying the free surface condition in the vicinity of the stagnation point and using the limiting transition with respect to the main parameter lead to the relation for the rise velocity of a Taylor bubble expressed in terms of the Froude number. In order to validate the method of superposition, it was applied to the problem of the rise of a plane Taylor bubble in a flat gap, which also has an exact analytical solution obtained with the help of the complex variable theory.
Rayleigh-Taylor instability-fascinating gateway to the study of fluid dynamics
Benjamin, Robert F.
1999-09-01
Rayleigh-Taylor instability, the flow instability at a horizontal interface between two fluids with different densities, is demonstrated by a series of experiments that are suited for secondary and college level teaching. (c) 1999 American Institute of Physics.
Application of the Priestley-Taylor Approach in a Two-Source Surface Energy Balance Model
USDA-ARS?s Scientific Manuscript database
The Priestley-Taylor (PT) approximation for computing evapotranspiration was initially developed for conditions of a horizontally uniform saturated surface, sufficiently extended to obviate any significant advection of energy. Nevertheless, the PT approach has been proven efficient within the frame...
Taylor-Couette flow instabilities in neutrally-buoyant suspensions
NASA Astrophysics Data System (ADS)
Majji, Madhu; Banerjee, Sanjoy; Morris, Jeffrey F.
2016-11-01
Experimentally-determined instabilities and flow states of a neutrally-buoyant suspension are described. The flow is studied in a concentric-cylinder device with inner-to-outer cylinder ratio of 0.877 with inner cylinder rotating and outer stationary. The cylinder length to annular gap ratio is 20, while the gap to particle size ratio is approximately 30, for spherical particles of 250 μm diameter. Using a slowly increasing or decreasing Re ramp, the flow agrees with all expectations for the pure fluid, while a slowly decreasing (quasi-static) ramp is used for the suspension flow, which is found to be unstable at lower Reynolds number Re (based on the effective viscosity) than pure fluid, and exhibits spiraling and ribbon states not found for a pure fluid with only inner cylinder rotating. Strikingly, the suspension at solid fraction ϕ >= 0 . 05 goes unstable first to a nonaxisymetric state rather than axisymmetric Taylor vortices. At 0 . 1 <= ϕ <= 0 , 2 , the flow exhibits numerous states during quais-static ramping of Re , while for ϕ = 0 . 3 , the base state Couette flow gives way to wavy spirals (WS) at Re 80 and exhibits only the WS state up to Re = 150 . Transient behavior on sudden change of Re and particle tracking will also be presented.
Late time phenomena of single mode Rayleigh-Taylor instability
NASA Astrophysics Data System (ADS)
Lin, An-Der
The development of single mode Rayleigh-Taylor (RT) instability, consists of three different stages, described as the linear, free fall and terminal velocity regimes. This instability and its three regimes have been studied in detail [49]. The central result of this thesis is the discovery of a fourth regime of oscillatory or nonuniform behavior after an apparent terminal velocity has been reached, especially for fluids whose density contrast is not too large. This result is based on numerical investigation by the Front Tracking method. The discovery documented here requires a modification to common beliefs regarding the late time evolution of a single mode disturbance. After a short time period of spike (bubble) pseudo terminal velocity plateau, the velocity resumes its increase reaches a new peak, and then decreases. The overall velocity development is sensitive to the Atwood number of the fluids. We show a relation between the spike (bubble) velocity and the tip curvature evolution. A linear relation between the spike (bubble) velocity and a pressure difference at the tips is also found. This pressure difference is the difference between the pressure at the spike (bubble) tip and the ambient pressure at the tip. The pressure difference reflects the pressure gradient at the tip. Numerical evidence shows that the pressure difference is strongly correlated to the spike (bubble) velocity development. The purpose of this work is to report these newly observed phenomena.
Fluctuation scaling in complex systems: Taylor's law and beyond
NASA Astrophysics Data System (ADS)
Eisler, Zoltán; Bartos, Imre; Kertész, János
2008-01-01
Complex systems consist of many interacting elements which participate in some dynamical process. The activity of various elements is often different and the fluctuation in the activity of an element grows monotonically with the average activity. This relationship is often of the form 'fluctuations ≈ constant × averageα', where the exponent α is predominantly in the range [1/2, 1]. This power law has been observed in a very wide range of disciplines, ranging from population dynamics through the Internet to the stock market and it is often treated under the names Taylor's law or fluctuation scaling. This review attempts to show how general the above scaling relationship is by surveying the literature, as well as by reporting some new empirical data and model calculations. We also show some basic principles that can underlie the generality of the phenomenon. This is followed by a mean-field framework based on sums of random variables. In this context the emergence of fluctuation scaling is equivalent to some corresponding limit theorems. In certain physical systems fluctuation scaling can be related to finite size scaling.
Taylor Dispersion Analysis of Polysaccharides Using Backscattering Interferometry.
Saetear, Phoonthawee; Chamieh, Joseph; Kammer, Michael N; Manuel, Thomas J; Biron, Jean-Philippe; Bornhop, Darryl J; Cottet, Hervé
2017-06-20
Taylor dispersion analysis (TDA) allows the determination of the molecular diffusion coefficient (D) or the hydrodynamic radius (Rh) of a solute from the peak broadening of a plug of solute in a laminar Poiseuille flow. The main limitation plaguing the broader applicability of TDA is the lack of a sensitive detection modality. UV absorption is typically used with TDA but is only suitable for UV-absorbing or derivatized compounds. In this work, we present a development of the TDA method for non-UV absorbing compounds by using a universal detector based on refractive index (RI) sensing with backscattering interferometry (BSI). BSI was interfaced to a capillary electrophoresis-UV instrument using a polyimide coated fused silica capillary and an in-house designed flow-cell assembly. Polysaccharides were selected to demonstrate the application of TDA-BSI for size characterization. Under the conditions of validity of TDA, D and Rh average values and the entire Rh distributions were obtained from the (poly)saccharide taylorgrams, including non-UV absorbing polymers.
Rigid spherical particles in highly turbulent Taylor-Couette flow
NASA Astrophysics Data System (ADS)
Bakhuis, Dennis; Verschoof, Ruben A.; Mathai, Varghese; Huisman, Sander G.; Lohse, Detlef; Sun, Chao
2016-11-01
Many industrial and maritime processes are subject to enormous frictional losses. Reducing these losses even slightly will already lead to large financial and environmental benefits. The understanding of the underlying physical mechanism of frictional drag reduction is still limited, for example, in bubbly drag reduction there is an ongoing debate whether deformability and bubble size are the key parameters. In this experimental study we report high precision torque measurements using rigid non-deformable spherical particles in highly turbulent Taylor-Couette flow with Reynolds numbers up to 2 ×106 . The particles are made of polystyrene with an average density of 1.036 g cm-3 and three different diameters: 8mm, 4mm, and 1.5mm. Particle volume fractions of up to 6% were used. By varying the particle diameter, density ratio of the particles and the working fluid, and volume fraction of the particles, the effect on the torque is compared to the single phase case. These systematic measurements show that adding rigid spherical particles only results in very minor drag reduction. This work is financially supported by Netherlands Organisation for Scientific Research (NWO) by VIDI Grant Number 13477.
Direct Numerical Simulation of Rayleigh-Taylor Instability
NASA Astrophysics Data System (ADS)
Cook, Andrew W.; Dimotakis, Paul E.
1999-11-01
Direct numerical simulations of Rayleigh-Taylor-Instability flows in a rectangular domain were performed on the ASCI Blue-Pacific computer at Lawrence Livermore National Laboratory. The code solves the Navier-Stokes equations, plus species-continuity equations with Fickian diffusion for two incompressible, miscible fluids with a 3:1 density ratio. The fluids are initially separated by a diffuse interface with broad-banded isotropic perturbations applied to the contact region. Several runs were performed with different initial conditions. Periodic boundary conditions are imposed in the horizontal directions with no-slip walls at the top and bottom of the computational domain. Neumann conditions on pressure are applied on the top/bottom walls. Domain decomposition is used to achieve a high degree of parallelism on 96 processors with a computational mesh of 256x256x512 grid points. The flow Reynolds number, based on the vertical-extent and growth-rate of the mixing region, reaches about 1100 by the end of the calculations. The results indicate that the flow remains sensitive to initial conditions, at least for the time spanned in these simulations.
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).
RAYLEIGH–TAYLOR UNSTABLE FLAMES—FAST OR FASTER?
Hicks, E. P.
2015-04-20
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.
Explicit analytic formulas for Newtonian Taylor-Couette primary instabilities.
Dutcher, C S; Muller, S J
2007-04-01
In this study, existing primary stability boundary data for flow between concentric cylinders, for the broad range of radius and rotation ratios examined, were found to be self-similar in a properly chosen parameter space. The experimental results for the primary transitions to both Taylor vortex flow and spiral vortex flow collapsed onto a single curve using a combination of variables technique, for both counter-rotating and co-rotating cylinders. The curves were then empirically fit, yielding explicit analytic formulas for the critical Reynolds number for any radius ratio (eta) and rotation ratio (micro) . For counter-rotating flows, the primary critical Reynolds number is determined by a single variable: the ratio of the nodal gap fraction to a known function of the radius ratio. The existence and influence of a nodal surface is shown experimentally for micro approximately equal -1.7. For co-rotating flows, the important scaled variable was found to be the radius ratio divided by the nodal radius ratio. Comparisons of the resulting explicit stability formulas were made to existing analytic stability expressions and experimental data. Excellent quantitative agreement was found with data across the entire parameter space.
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.
Structures and Lagrangian statistics of the Taylor-Green dynamo
NASA Astrophysics Data System (ADS)
Homann, H.; Ponty, Y.; Krstulovic, G.; Grauer, R.
2014-07-01
The evolution of a Taylor-Green forced magnetohydrodynamic system showing dynamo activity is analyzed via direct numerical simulations. The statistical properties of the velocity and magnetic fields in Eulerian and Lagrangian coordinates are found to change between the kinematic, nonlinear and saturated regime. Fluid element (tracer) trajectories change from chaotic quasi-isotropic (kinematic phase) to mean magnetic field aligned (saturated phase). The probability density functions (PDFs) of the magnetic field change from strongly non-Gaussian in the kinematic to quasi-Gaussian PDFs in the saturated regime so that their flatness give a precise handle on the definition of the limiting points of the three regimes. Also the statistics of the kinetic and magnetic fluctuations along fluid trajectories changes. All this goes along with a dramatic increase of the correlation time of the velocity and magnetic fields experienced by tracers, significantly exceeding one turbulent large-eddy turn-over time. A remarkable consequence is an intermittent scaling regime of the Lagrangian magnetic field structure functions at unusually long time scales.
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.
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.
Turbulent Taylor-Couette Flow at Large Reynolds Numbers*
NASA Astrophysics Data System (ADS)
Babkin, V. A.
2016-09-01
The problem of the steady-state turbulent flow of an incompressible fluid in the clearance between two coaxial infinite circular cylinders of radii R1 and R2, caused by the rotation of the inner cylinder of radius R1 under the conditions where the outer cylinder of radius R2 is immovable, i.e., the problem of a Taylor-Couette flow, was solved numerically within the framework of the model of a near-wall anisotropic turbulence with regard for the action of the centrifugal forces on the near-wall vortex structures determining the character of the flow between the cylinders. The profiles of the angular velocities of the fluid flowing along the radius of the clearance between the cylinders in the regime of completely developed turbulence were determined by numerical integration of the equation of motion of this fluid. The results of calculations of the flow between the cylinders at R1/R2 = 0.716 and Re = 105, 106, and 2·106 were compared with known solutions of the problem being considered and corresponding experimental data.
A guide frame for the Taylor Spatial Frame.
Kanellopoulos, Anastasios D; Mavrogenis, Andreas F; Kanellopoulos, Nikolaos D; Magnissalis, Evangellos A; Papagelopoulos, Panayiotis J
2009-08-01
The Taylor Spatial Frame (TSF) is a versatile multiplanar external fixator that combines ease of application with computer accuracy to effectively reduce fractures and correct all aspects of deformity in reconstructive orthopaedic surgery. However, postapplication adjustments depend on adequate anteroposterior and lateral radiographic measurements to yield the most accurate output from the program. These radiographs need to be taken in an orthogonal plane to the reference ring. We describe a noninvasive technique using a specifically designed radiolucent frame that can be attached to the TSF to guide the surgeon and radiologist in obtaining lateral and anteroposterior radiographs, with the reference ring perfectly orthogonal in single exposures for each radiographic view. By using this guiding frame, reproducible and consistent x-rays oriented orthogonally to the reference ring at different points in the correction may be achieved, thus eliminating the need for repeat radiographs and radiation exposure for patients, radiologists, and surgeons. In this manner, the mounting parameters and the orientation of the bony deformity will be consistent. This should lead to enhanced accuracy of the TSF correction.
DSMC Simulations of the Rayleigh-Taylor Instability in Gases
NASA Astrophysics Data System (ADS)
Gallis, Michael; Koehler, Timothy; Torczynski, John; Plimpton, Steven
2015-11-01
The Direct Simulation Monte Carlo (DSMC) method of molecular gas dynamics is applied to simulate the Rayleigh-Taylor instability (RTI) in atmospheric-pressure monatomic gases (e.g., argon and helium). The computational domain is a 1 mm × 4 mm rectangle divided into 50-nm square cells. Each cell is populated with 1000 computational molecules, and time steps of 0.1 ns are used. Simulations are performed to quantify the growth of a single-mode perturbation on the interface as a function of the Atwood number and the gravitational acceleration. The DSMC results qualitatively reproduce all observed features of the RTI and are in reasonable quantitative agreement with existing theoretical and empirical models. Consistent with previous work in this field, the DSMC simulations indicate that the growth of the RTI follows a universal behavior. For cases with multiple-mode perturbations, the numbers of bubble-spike pairs that eventually appear are found to be in agreement with theoretical results for the most unstable wavelength. 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 National Nuclear Security Administration under contract DE-AC04-94AL85000.
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.
Pulsed power driven Magneto-Rayleigh-Taylor experiments.
Sefkow, Adam B.; Peterson, Kyle J.; Rovang, Dean Curtis; Slutz, Stephen A.; Cuneo, Michael Edward; Vesey, Roger Alan; Herrmann, Mark C.; Sinars, Daniel Brian
2010-03-01
Numerical simulations indicate that significant fusion yields (>100 kJ) may be obtained by pulsed-power-driven implosions of cylindrical metal liners onto magnetized and preheated deuterium-tritium fuel. The primary physics risk to this approach is the Magneto-Rayleigh-Taylor (MRT) instability, which operates during both the acceleration and deceleration phase of the liner implosion. We have designed and performed some experiments to study the MRT during the acceleration phase, where the light fluid is purely magnetic. Results from our first series of experiments and plans for future experiments will be presented. According to simulations, an initial axial magnetic field of 10 T is compressed to >100 MG within the liner during the implosion. The magnetic pressure becomes comparable to the plasma pressure during deceleration, which could significantly affect the growth of the MRT instability at the fuel/liner interface. The MRT instability is also important in some astronomical objects such as the Crab Nebula (NGC1962). In particular, the morphological structure of the observed filaments may be determined by the ratio of the magnetic to material pressure and alignment of the magnetic field with the direction of acceleration [Hester, ApJ, 456, 225 1996]. Potential experiments to study this MRT behavior using the Z facility will be presented.
Weakly nonlinear incompressible Rayleigh-Taylor instability in spherical geometry
NASA Astrophysics Data System (ADS)
Zhang, J.; Wang, L. F.; Ye, W. H.; Wu, J. F.; Guo, H. Y.; Zhang, W. Y.; He, X. T.
2017-06-01
In this research, a weakly nonlinear (WN) model for the incompressible Rayleigh-Taylor instability in cylindrical geometry [Wang et al., Phys. Plasmas 20, 042708 (2013)] is generalized to spherical geometry. The evolution of the interface with an initial small-amplitude single-mode perturbation in the form of Legendre mode (Pn) is analysed with the third-order WN solutions. The transition of the small-amplitude perturbed spherical interface to the bubble-and-spike structure can be observed by our model. For single-mode perturbation Pn, besides the generation of P 2 n and P 3 n , which are similar to the second and third harmonics in planar and cylindrical geometries, many other modes in the range of P0- P 3 n are generated by mode-coupling effects up to the third order. With the same initial amplitude, the bubbles at the pole grow faster than those at the equator in the WN regime. Furthermore, it is found that the behavior of the bubbles at the pole is similar to that of three-dimensional axisymmetric bubbles, while the behavior of the bubbles at the equator is similar to that of two-dimensional bubbles.
Nonlinear dynamics in eccentric Taylor-Couette-Poiseuille flow
NASA Astrophysics Data System (ADS)
Pier, Benoît; Caulfield, C. P.
2015-11-01
The flow in the gap between two parallel but eccentric cylinders and driven by an axial pressure gradient and inner cylinder rotation is characterized by two geometrical parameters (radius ratio and eccentricity) and two dynamic parameters (axial and azimuthal Reynolds numbers). Such a theoretical configuration is a model for the flow between drill string and wellbore in the hydrocarbon drilling industry. The linear convective and absolute instability properties have been systematically derived in a recent study [Leclercq, Pier & Scott, J. Fluid Mech. 2013 and 2014]. Here we address the nonlinear dynamics resulting after saturation of exponentially growing small-amplitude perturbations. By using direct numerical simulations, a range of finite-amplitude states are found and characterized: nonlinear traveling waves (an eccentric counterpart of Taylor vortices, associated with constant hydrodynamic loading on the inner cylinder), modulated nonlinear waves (with time-periodic torque and flow rate) and more irregular states. In the nonlinear regime, the hydrodynamic forces are found to depart significantly from those prevailing for the base flow, even in situations of weak linear instability.
Compressibility effects in Rayleigh-Taylor instability-induced flows.
Gauthier, S; Le Creurer, B
2010-04-13
We present a tentative review of compressibility effects in Rayleigh-Taylor instability-induced flows. The linear, nonlinear and turbulent regimes are considered. We first make the classical distinction between the static compressibility or stratification, and the dynamic compressibility owing to the finite speed of sound. We then discuss the quasi-incompressible limits of the Navier-Stokes equations (i.e. the low-Mach number, anelastic and Boussinesq approximations). We also review some results about stratified compressible flows for which instability criteria have been derived rigorously. Two types of modes, convective and acoustic, are possible in these flows. Linear stability results for perfect fluids obtained from an analytical approach, as well as viscous fluid results obtained from numerical approaches, are also reviewed. In the turbulent regime, we introduce Chandrasekhar's observation that the largest structures in the density fluctuations are determined by the initial conditions. The effects of compressibility obtained by numerical simulations in both the nonlinear and turbulent regimes are discussed. The modifications made to statistical models of fully developed turbulence in order to account for compressibility effects are also treated briefly. We also point out the analogy with turbulent compressible Kelvin-Helmholtz mixing layers and we suggest some lines for further investigations.
Inviscid helical magnetorotational instability in cylindrical Taylor-Couette flow.
Priede, Jānis
2011-12-01
This paper presents the analysis of axisymmetric helical magnetorotational instability (HMRI) in the inviscid limit, which is relevant for astrophysical conditions. The inductionless approximation defined by zero magnetic Prandtl number is adopted to distinguish the HMRI from the standard MRI in the cylindrical Taylor-Couette flow subject to a helical magnetic field. Using a Chebyshev collocation method convective and absolute instability thresholds are computed in terms of the Elsasser number for a fixed ratio of inner and outer radii λ = 2 and various ratios of rotation rates and helicities of the magnetic field. It is found that the extension of self-sustained HMRI modes beyond the Rayleigh limit does not reach the astrophysically relevant Keplerian rotation profile not only in the narrow- but also in the finite-gap approximation. The Keppler limit can be attained only by the convective HMRI mode provided that the boundaries are perfectly conducting. However, this mode requires not only a permanent external excitation to be observable but also has a long axial wavelength, which is not compatible with limited thickness of astrophysical accretion disks.
GRAVITATIONALLY UNSTABLE FLAMES: RAYLEIGH-TAYLOR STRETCHING VERSUS TURBULENT WRINKLING
Hicks, E. P.; Rosner, R.
2013-07-10
In this paper, we provide support for the Rayleigh-Taylor-(RT)-based subgrid model used in full-star simulations of deflagrations in Type Ia supernovae explosions. We use the results of a parameter study of two-dimensional direct numerical simulations of an RT unstable model flame to distinguish between the two main types of subgrid models (RT or turbulence dominated) in the flamelet regime. First, we give scalings for the turbulent flame speed, the Reynolds number, the viscous scale, and the size of the burning region as the non-dimensional gravity (G) is varied. The flame speed is well predicted by an RT-based flame speed model. Next, the above scalings are used to calculate the Karlovitz number (Ka) and to discuss appropriate combustion regimes. No transition to thin reaction zones is seen at Ka = 1, although such a transition is expected by turbulence-dominated subgrid models. Finally, we confirm a basic physical premise of the RT subgrid model, namely, that the flame is fractal, and thus self-similar. By modeling the turbulent flame speed, we demonstrate that it is affected more by large-scale RT stretching than by small-scale turbulent wrinkling. In this way, the RT instability controls the flame directly from the large scales. Overall, these results support the RT subgrid model.
Dependence of turbulent Rayleigh-Taylor instability on initial perturbations.
Dimonte, Guy
2004-05-01
The dependency of the self-similar Rayleigh-Taylor bubble acceleration constant alpha(b)(identical with [(amplitude)/2] x (displacement) x (Atwood number)) on the initial perturbation amplitude h(0k) is described with a model in which the exponential growth of a small amplitude packet of modes makes a continuous nonlinear transition to its "terminal" bubble velocity proportional, variant Fr[equal to(Froude number)(1/2)]. Then, by applying self-similarity (diameter proportional, variant amplitude), alpha(b) is found to increase proportional to Fr and logarithmically with h(0k). The model has two free parameters that are determined from experiments and simulations. The augmentation of long wavelength perturbations by mode coupling is also evaluated. This is found to decrease the sensitivity of alpha(b) on the initial perturbations when they are smaller than the saturation amplitude of the most unstable modes. These results show that alpha(b) can vary by a factor of 2-3 with initial conditions in reasonable agreement with experiments and simulations.
Rayleigh-Taylor instabilities with sheared magnetic fields
Ruderman, M. S.; Terradas, J.; Ballester, J. L.
2014-04-20
Magnetic Rayleigh-Taylor (MRT) instabilities may play a relevant role in many astrophysical problems. In this work the effect of magnetic shear on the growth rate of the MRT instability is investigated. The eigenmodes of an interface and a slab model under the presence of gravity are analytically calculated assuming that the orientation of the magnetic field changes in the equilibrium, i.e., there is magnetic shear. We solve the linearized magnetohydrodynamic equations in the incompressible regime. We find that the growth rate is bounded under the presence of magnetic shear. We have derived simple analytical expressions for the maximum growth rate, corresponding to the most unstable mode of the system. These expressions provide the explicit dependence of the growth rate on the various equilibrium parameters. For small angles the growth time is linearly proportional to the shear angle, and in this regime the single interface problem and the slab problem tend to the same result. On the contrary, in the limit of large angles and for the interface problem the growth time is essentially independent of the shear angle. In this regime we have also been able to calculate an approximate expression for the growth time for the slab configuration. Magnetic shear can have a strong effect on the growth rates of the instability. As an application of the results found in this paper we have indirectly determined the shear angle in solar prominence threads using their lifetimes and the estimation of the Alfvén speed of the structure.
Boundary Condition Effects on Taylor States in SSX
NASA Astrophysics Data System (ADS)
Han, Jeremy; Shrock, Jaron; Kaur, Manjit; Brown, Michael; Schaffner, David
2016-10-01
Three different boundary conditions are applied to the SSX 0.15 m diameter plasma wind tunnel and the resultant Taylor states are characterized. The glass walls of the wind tunnel act as an insulating boundary condition. For the second condition, a flux conserver is wrapped around the tunnel to trap magnetic field lines inside the SSX. For the last condition, the flux conserver is segmented to add theta pinch coils, which will accelerate the plasma. We used resistive stainless steel and copper mesh for the flux conservers, which have soak times of 3 μs and 250 μs , respectively. The goal is to increase the speed, temperature, and density of the plasma plume by adding magnetic energy into the system using the coils and compressing the plasma into small volumes by stagnation. The time of flight is measured by using a linear array of magnetic pick-up loops, which track the plasma plume's location as a function of time. The density is measured by precision quadrature He-Ne laser interferometry, and the temperature is measured by ion Doppler spectroscopy. Speed and density without the coils are 30km /s and 1015cm-3 . We will reach a speed of 100km /s and density of 1016cm-3 by adding the coil. Work supported by DOE OFES and ARPA-E ALPHA program.
Stratorotational instability in a thermally stratified Taylor-Couette Flow
NASA Astrophysics Data System (ADS)
Harlander, Uwe; Seelig, Torsten; Gellert, Marcus; Viazzo, Stephane; Randriamampianina, Anthony; Egbers, Christoph; Rüdiger, Günther
2015-04-01
Thirty years ago it was observed that for many stars the emitted energy spectrum shows an extra bump in the infrared part. This infrared excess indicates a large gaseous disk encompassing the star. Such accretion disks are regions of planet formation. Understanding the mechanisms that can result in an outward angular momentum transport is the central problem of planet formation, particularly in the theory of accretion disks. When a planet forms in a disk, angular momentum has to be carried away from the planet otherwise its rotation speed would be far too large. Only turbulence can achieve such a large angular momentum transport. Accretion disks can be turbulent even in the absence of a magnetic field. However, it is still an open question whether purely hydrodynamic instabilities are efficient enough for the momentum transport. This question can be addressed by particularly designed laboratory experiments and numerical simulations in an Taylor-Couette (TC) setup. It has been shown that classical turbulent TC flows are not efficient enough. However, adding axial stratification opens a route to a new instability. This Stratorotational Instability (SRI) has attracted attention in recent years. We show preliminary experimental and numerical results that highlight nonlinear aspects of the flow.
Cylindrical Effects on Magneto-Rayleigh-Taylor Instability
NASA Astrophysics Data System (ADS)
Weis, Matthew; Lau, Yue Ying; Gilgenbach, Ronald; Jennings, Christopher; Hess, Mark
2012-10-01
This paper concentrates on the effects of cylindrical geometry on the magneto-Rayleigh-Taylor instability (MRT), a major concern in the magnetized liner inertial fusion concept (MagLIF) [1]. Several issues are being studied, such as the Bell-Plesset effect [2], the effects of magnetic shear and feedthrough [3], and the nonzero MRT growth rate that remains (but was hardly noticed) in the k = m = 0 limit in Harris' seminal paper on a cylindrical liner [4], where k and m are respectively the azimuthal and axial wavenumber. We shall use simulation and direct integration of the eigenvalue equation to investigate the importance of the cylindrical geometry, which is particularly relevant in the final stage of compression in the MagLIF concept. [4pt] [1] S. A. Slutz, et. al, Phys. Plasmas 17, 056303 (2010). [0pt] [2] G. I. Bell, Los Alamos Scientific Laboratory, Report LA-1321 (1951); M. S. Plesset, J. Appl. Phys. 25, 96 (1954).[0pt] [3] P. Zhang et al., Phys. Plasmas 19, 200703 (2012); Y. Y. Lau et al., Phys. Rev. E 83, 006405 (2011). [0pt] [4] E. G. Harris, Phys. Fluids 5, 1057 (1962).
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.
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.
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.
Viscous-resistive layer in Rayleigh-Taylor instability
NASA Astrophysics Data System (ADS)
Silveira, F. E. M.; Orlandi, H. I.
2017-03-01
In this work, new scaling laws of the time growth rate γ of the Rayleigh-Taylor instability with the plasma resistivity η, kinematic viscosity ν, and electron number density ne are derived. A viscosity scale is defined in terms of the time decay of the perturbative fluid flow perpendicular to the equilibrium magnetic field, at the quasi-static approximation. Such a scale provides the identification of a viscous layer that can be combined with the resistive layer to produce a viscous-resistive layer. The latter, in turn, is found to satisfy an algebraic biquadratic equation. When viscous effects are negligible, it is shown that the viscous-resistive layer is given by the resistive layer. Somewhat surprisingly, when viscous effects cannot be neglected, it is shown that the viscous-resistive layer is given by the geometric mean of the resistive and viscous layers. A dispersion relation for the time growth rate is derived in terms of the viscous-resistive layer. When viscous effects cannot be neglected, two new scaling laws are found. At the quasi-static approximation, it is shown that γ ˜ (ην)1/4. However, on account of a finite electron mass, it is shown that γ˜(ν/ne ) 1 /3 . Further developments of our formulation are addressed in connection with a finite compressibility in the perturbative flow.
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.
Sharma, H; Nunn, T
2013-08-01
The closure of small-to-moderate-sized soft tissue defects in open tibial fractures can be successfully achieved with acute bony shortening. In some instances, it may be possible to close soft tissue envelope defects by preserving length and intentionally creating a deformity of the limb. As the soft tissue is now able to close, this manoeuvre converts an open IIIb to IIIa fracture. This obviates the need for soft tissue reconstructive procedures such as flaps and grafts, which have the potential to cause donor-site morbidity and may fail. In this article, the authors demonstrate the technique for treating anterior medial soft tissue defects by deforming the bone at the fracture site, permitting temporary malalignment and closure of the wound. After healing of the envelope, the malalignment is gradually corrected with the use of the Taylor Spatial Frame. We present two such cases and discuss the technical indications and challenges of managing such cases.
Treatment of complex tibial fractures in children with the taylor spatial frame.
Eidelman, Mark; Katzman, Alexander
2008-10-01
Most tibial shaft fractures in children can be treated with closed reduction and cast fixation, but some fractures need external or internal fixation. The Taylor spatial frame (Smith & Nephew, Memphis, Tennessee) is a relatively new external fixator that can correct 6-axis deformities with computer accuracy. This article reports our experience using the Taylor spatial frame as a rewarding treatment modality for complex tibial fractures in children and adolescents.
Maudlin, P.J.; Bingert, J.F.; House, J.W.
1997-04-01
Taylor impact tests using specimens cut from a rolled plate of Ta were conducted. The Ta was well-characterized in terms of flow stress and crystallographic texture. A piece-wise yield surface was interrogated from this orthotropic texture, and used in EPIC-95 3D simulations of the Taylor test. Good agreement was realized between the calculations and the post-test geometries in terms of major and minor side profiles and impact-interface footprints.
Experimental and numerical analysis of Al6063 duralumin using Taylor impact test
NASA Astrophysics Data System (ADS)
Kruszka, L.; Anaszewicz, Ł.; Janiszewski, J.; Grązka, M.
2012-08-01
The paper presents results of experimental and numerical analysis of dynamic behaviour Al6063 duralumin. Dynamical experiments were made using Taylor impact test. Experimental results at next step of study were used in numerical analyses of dynamic yield stress of tested material and model parameters of the Johnson-Cook constitutive equation. The main aim of this analysis is to find out dynamical properties of Al6063 duralumin tested in Taylor impact test.
A Taylor-Galerkin finite element algorithm for transient nonlinear thermal-structural analysis
NASA Technical Reports Server (NTRS)
Thornton, Earl A.; Dechaumphai, Pramote
1985-01-01
A Taylor-Galerkin finite element solution algorithm for transient nonlinear thermal-structural analysis of large, complex structural problems subjected to rapidly applied thermal-structural loads is described. The two-step Taylor-Galerkin algorithm is an application of an algorithm recently developed for problems in compressible fluid dynamics. The element integrals that appear in the algorithm can be evaluated in closed form for two and three dimensional elements.
Taylor Dispersion Analysis as a promising tool for assessment of peptide-peptide interactions.
Høgstedt, Ulrich B; Schwach, Grégoire; van de Weert, Marco; Østergaard, Jesper
2016-10-10
Protein-protein and peptide-peptide (self-)interactions are of key importance in understanding the physiochemical behavior of proteins and peptides in solution. However, due to the small size of peptide molecules, characterization of these interactions is more challenging than for proteins. In this work, we show that protein-protein and peptide-peptide interactions can advantageously be investigated by measurement of the diffusion coefficient using Taylor Dispersion Analysis. Through comparison to Dynamic Light Scattering it was shown that Taylor Dispersion Analysis is well suited for the characterization of protein-protein interactions of solutions of α-lactalbumin and human serum albumin. The peptide-peptide interactions of three selected peptides were then investigated in a concentration range spanning from 0.5mg/ml up to 80mg/ml using Taylor Dispersion Analysis. The peptide-peptide interactions determination indicated that multibody interactions significantly affect the PPIs at concentration levels above 25mg/ml for the two charged peptides. Relative viscosity measurements, performed using the capillary based setup applied for Taylor Dispersion Analysis, showed that the viscosity of the peptide solutions increased with concentration. Our results indicate that a viscosity difference between run buffer and sample in Taylor Dispersion Analysis may result in overestimation of the measured diffusion coefficient. Thus, Taylor Dispersion Analysis provides a practical, but as yet primarily qualitative, approach to assessment of the colloidal stability of both peptide and protein formulations.
The stability of Taylor bubbles in large-diameter tubes: Linear theory
NASA Astrophysics Data System (ADS)
Abubakar, Habib; Matar, Omar
2015-11-01
Taylor bubbles are a characteristic feature of the slug flow regime in gas-liquid pipe flows. With increasing pipe diameter, previous experimental observations have shown that at sufficiently large diameter (> 0.1 m), the slug flow regime, and hence Taylor bubbles, are not observed in gas-liquid flows in vertical pipes. Numerical simulations of a Taylor bubble rising in a quiescent liquid (see companion talk at this APS/DFD conference) have also shown that the wake of Taylor bubbles rising in a riser of such sizes is turbulent and has great impact on the stability of the subsequent, trailing bubbles. In view of these observations, a linear stability analysis is carried out to establish the stability conditions for a Taylor bubble rising in a turbulent flowing liquid. The stability of an axisymmetric Taylor bubble to a small-amplitude, three dimensional, perturbation is studied and the dimensionless flow parameters of the liquid investigated include the Froude number, the inverse viscosity number, and the Eotvos numbers. Nigerian Government scholarship (for HA).
Distribution of glacial deposits, soils, and permafrost in Taylor Valley, Antarctica
Bockheim, James G.; Prentice, M.L.; McLeod, M.
2008-01-01
We provide a map of lower and central Taylor Valley, Antarctica, that shows deposits from Taylor Glacier, local alpine glaciers, and grounded ice in the Ross Embayment. From our electronic database, which includes 153 sites from the coast 50 km upvalley to Pearse Valley, we show the distribution of permafrost type and soil subgroups according to Soil Taxonomy. Soils in eastern Taylor Valley are of late Pleistocene age, cryoturbated due to the presence of ground ice or ice-cemented permafrost within 70 cm of the surface, and classified as Glacic and Typic Haploturbels. In central Taylor Valley, soils are dominantly Typic Anhyorthels of mid-Pleistocene age that have dry-frozen permafrost within the upper 70 cm. Salt-enriched soils (Salic Anhyorthels and Petrosalic Anhyorthels) are of limited extent in Taylor Valley and occur primarily on drifts of early Pleistocene and Pliocene age. Soils are less developed in Taylor Valley than in nearby Wright Valley, because of lesser salt input from atmospheric deposition and salt weathering. Ice-cemented permafrost is ubiquitous on Ross Sea, pre-Ross Sea, and Bonney drifts that occur within 28 km of the McMurdo coast. In contrast, dry-frozen permafrost is prevalent on older (???115 ky) surfaces to the west. ?? 2008 Regents of the University of Colorado.
High-order Taylor series expansion methods for error propagation in geographic information systems
NASA Astrophysics Data System (ADS)
Xue, Jie; Leung, Yee; Ma, Jiang-Hong
2015-04-01
The quality of modeling results in GIS operations depends on how well we can track error propagating from inputs to outputs. Monte Carlo simulation, moment design and Taylor series expansion have been employed to study error propagation over the years. Among them, first-order Taylor series expansion is popular because error propagation can be analytically studied. Because most operations in GIS are nonlinear, first-order Taylor series expansion generally cannot meet practical needs, and higher-order approximation is thus necessary. In this paper, we employ Taylor series expansion methods of different orders to investigate error propagation when the random error vectors are normally and independently or dependently distributed. We also extend these methods to situations involving multi-dimensional output vectors. We employ these methods to examine length measurement of linear segments, perimeter of polygons and intersections of two line segments basic in GIS operations. Simulation experiments indicate that the fifth-order Taylor series expansion method is most accurate compared with the first-order and third-order method. Compared with the third-order expansion; however, it can only slightly improve the accuracy, but on the expense of substantially increasing the number of partial derivatives that need to be calculated. Striking a balance between accuracy and complexity, the third-order Taylor series expansion method appears to be a more appropriate choice for practical applications.
Taylor-Couette instability in thixotropic yield stress fluids
NASA Astrophysics Data System (ADS)
Jenny, Mathieu; Kiesgen de Richter, Sébastien; Louvet, Nicolas; Skali-Lami, Salahedine; Dossmann, Yvan
2017-02-01
We consider the flow of thixotropic yield stress fluids between two concentric cylinders. To account for the fluid thixotropy, we use Hou\\vska's model [Hou\\vska, Ph.D. thesis, Czech Technical University, Prague, 1981] with a single structural parameter driven by a kinetic equation. Because of the yield stress and the geometric inhomogeneity of the stress, only a part of the material in the gap may flow. Depending on the breakdown rate of the structural parameter, the constitutive relation can lead to a nonmonotonic flow curve. This nonmonotonic behavior is known to induce a discontinuity in the slope of the velocity profile within the flowing material, called shear banding. Thus, for fragile structures, a shear-banded flow characterized by a very sharp transition between the flowing and the static regions may be observed. For stronger structures, the discontinuity disappears and a smooth transition between the flowing and the static regions is observed. The consequences of the thixotropy on the linear stability of the azimuthal flow are studied in a large range of parameters. Although the thixotropy allows shear banding in the base flow, it does not modify fundamentally the linear stability of the Couette flow compared to a simple yield stress fluid. The apparent shear-thinning behavior depends on the thixotropic parameters of the fluid and the results about the onset of the Taylor vortices in shear-thinning fluids are retrieved. Nevertheless, the shear banding modifies the stratification of the viscosity in the flowing zone such that the critical conditions are mainly driven by the width of the flowing region.
Thin Planar Foil Radiative Rayleigh-Taylor Instability*
NASA Astrophysics Data System (ADS)
Mason, R. J.; Hollowell, D. E.; Schappert, G. T.; Batha, S. H.
1999-11-01
We further^1 investigate the Rayleigh-Taylor instability of radiatively driven thin copper foils under pure ablation, as well as with beryllium tampers to provide additional pressure drive. The Cu foils were typically 11 μm thick with 0.5 μm amplitude cosine perturbations on the driven surface. The tampers were generally 5 μm thick, and either abutting the foils or placed some 200 μm away toward the drive, to provide some constant degree of light filtration; they were either flat or contoured to follow the initial cosine imprint on the foils. The foil packages were exposed to ``P26'' pulse, rising to 160 eV over 1.5 ns, then flat until 2.5 ns, and then dropping away. The radiation was produced in OMEGA tetrahedral hohlraums. Calculations with 1D LASNEX have shown that the greatest foil acceleration comes with the tamper at solid density (not a foam) and directly abutting the Copper. RAGE AMR calculations in 2D show a strong reduction of fine scale perturbation growth with the use of a high level initial mesh refinement along the perturbed interface, and by the action of electron thermal conduction. There is little sensitivity to tamper contouring. Good agreement is evident between the measured and predicted growth of the first harmonic out to 4.5 ns. \\vskip 3 pt ^1R. J. Mason, D. E. Hollowell, G. T. Schappert and S. E. Caldwell, Bull. Am. Phys. Soc. 43 1895 (1998). Work performed under the auspices of the U.S.D.O.E.
Rayleigh-Taylor Instability Evolution in Ablatively Driven Cylindrical Implosions^*,**
NASA Astrophysics Data System (ADS)
Hsing, W. W.
1996-11-01
The Rayleigh-Taylor instability is an important limitation in ICF capsule designs. Significant work both theoretically and experimentally has been done to demonstrate the stabilizing effects due to material flow through the unstable region. The experimental verification has been done predominantly in planar geometry. Convergent geometry introduces effects not present in planar geometry such as shell thickening and accelerationless growth of modal amplitudes (e.g. Bell-Plesset growth). Amplitude thresholds for the nonlinear regime are reduced, since the wavelength of a mode m decreases with convergence λ ~ r/m, where r is the radius. We have investigated convergent effects using an imploding cylinder driven by x-ray ablation on the NOVA laser. By doping sections of the cylinder with high-Z materials, in conjunction with x-ray backlighting, we have measured the growth and feedthrough of the perturbations from the ablation front to the inner surface of the cylinder for various initial modes and amplitudes from early time through stagnation. Mode coupling of illumination asymmetries with material perturbations is observed, as well as phase reversal of the perturbations from near the ablation front to the inner surface of the cylinder. Imaging is performed with an x-ray pinhole camera coupled to a gated microchannel plate detector. In collaboration with C. W. Barnes, J. B. Beck, N. Hoffman (LANL), D. Galmiche, A. Richard (CEA/L-V), J. Edwards, P. Graham, B. Thomas (AWE). ^**This work was performed under the auspices of the U.S. Department of Energy by the Los Alamos National Laboratory under Contract No. W-7405-ENG-36.
Statistical Tests of Taylor's Hypothesis: An Application to Precipitation Fields
NASA Astrophysics Data System (ADS)
Murthi, A.; Li, B.; Bowman, K.; North, G.; Genton, M.; Sherman, M.
2009-05-01
The Taylor Hypothesis (TH) as applied to rainfall is a proposition about the space-time covariance structure of the rainfall field. Specifically, it supposes that if a spatio-temporal precipitation field with a stationary covariance Cov(r, τ) in both space r and time τ, moves with a constant velocity v, then the temporal covariance at time lag τ is equal to the spatial covariance at space lag v τ, that is, Cov(0, τ) = Cov(v τ, 0). Qualitatively this means that the field evolves slowly in time relative to the advective time scale, which is often referred to as the 'frozen field' hypothesis. Of specific interest is whether there is a cut-off or decorrelation time scale for which the TH holds for a given mean flow velocity v. In this study the validity of the TH is tested for precipitation fields using high-resolution gridded NEXRAD radar reflectivity data produced by the WSI Corporation by employing two different statistical approaches. The first method is based upon rigorous hypothesis testing while the second is based on a simple correlation analysis, which neglects possible dependencies in the correlation estimates. We use radar reflectivity values from the southeastern United States with an approximate horizontal resolution of 4 km x 4 km and a temporal resolution of 15 minutes. During the 4-day period from 2 to 5 May 2002, substantial precipitation occurs in the region of interest, and the motion of the precipitation systems is approximately uniform. The results of both statistical methods suggest that the TH might hold for the shortest space and time scales resolved by the data (4 km and 15 minutes), but that it does not hold for longer periods or larger spatial scales. Also, the simple correlation analysis tends to overestimate the statistical significance through failing to account for correlations between the covariance estimates.
Particle classification in Taylor vortex flow with an axial flow
NASA Astrophysics Data System (ADS)
Ohmura, N.; Suemasu, T.; Asamura, Y.
2005-01-01
Particle classification phenomenon in Taylor vortex flow with an axial flow was investigated experimentally and numerically. The flow-visualization experiment by a laser-induced fluorescence method clearly revealed that there existed two distinct mixing regions at low Reynolds numbers. The tracer near the vortex cell boundary was rapidly transported axially owing to the bypass flow effect. On the other hand, the fluid element was confined to the vortex core region without being exchanged with the outer flow region. In order to observe particle classification phenomenon, polymethyl methacrylate (PMMA) particles suspended in the same aqueous solution of glycerol as the working fluid were fed into the top of the apparatus. Particle size was initially ranging from 10 to 80 µm. The ratio of the particle density to the fluid density was 1.04-1.05, which means the density difference between particle and fluid is very small. The suspended solution was withdrawn using a hypodermic needle every a certain time period at 30 mm above the bottom of apparatus. The fluid was sampled both near the outer wall and in vortex core. The particles sampled at 42 min having the size of 20-50 µm were mainly observed in the vortex core region. On the other hand, a large population of particles having the size of about 50-80 µm could be seen in the outer region of vortex. It was found that large particles located near the outer edge of vortices were quickly transported axially owing to the bypass flow effect. Numerical simulation also revealed that the loci of particles depended on the particle size.
Non-equilibrium Thermodynamics of Rayleigh-Taylor instability
NASA Astrophysics Data System (ADS)
Sengupta, Tapan K.; Sengupta, Aditi; Shruti, K. S.; Sengupta, Soumyo; Bhole, Ashish
2016-10-01
Rayleigh-Taylor instability (RTI) has been studied here as a non-equilibrium thermodynamics problem. Air masses with temperature difference of 70K, initially with heavier air resting on lighter air isolated by a partition, are allowed to mix by impulsively removing the partition. This results in interface instabilities, which are traced here by solving two dimensional (2D) compressible Navier-Stokes equation (NSE), without using Boussinesq approximation (BA henceforth). The non-periodic isolated system is studied by solving NSE by high accuracy, dispersion relation preserving (DRP) numerical methods described in Sengupta T.K.: High Accuracy Computing Method (Camb. Univ. Press, USA, 2013). The instability onset is due to misaligned pressure and density gradients and is evident via creation and evolution of spikes and bubbles (when lighter fluid penetrates heavier fluid and vice versa, associated with pressure waves). Assumptions inherent in compressible formulation are: (i) Stokes' hypothesis that uses zero bulk viscosity assumption and (ii) the equation of state for perfect gas which is a consequence of equilibrium thermodynamics. Present computations for a non-equilibrium thermodynamic process do not show monotonic rise of entropy with time, as one expects from equilibrium thermodynamics. This is investigated with respect to the thought-experiment. First, we replace Stokes' hypothesis, with another approach where non-zero bulk viscosity of air is taken from an experiment. Entropy of the isolated system is traced, with and without the use of Stokes' hypothesis. Without Stokes' hypothesis, one notes the rate of increase in entropy to be higher as compared to results with Stokes' hypothesis. We show this using the total entropy production for the thermodynamically isolated system. The entropy increase from the zero datum is due to mixing in general; punctuated by fluctuating entropy due to creation of compression and rarefaction fronts originating at the interface
Very-high-growth-factor Planar Ablative Rayleigh Taylor Experiments
Bradley, D K; Braun, D G; Glendinning, S G; Edwards, M J; Milovich, J L; Sorce, C M; Collins, G W; Haan, S W; Page, R H
2006-10-30
The Rayleigh-Taylor (RT) instability is an important factor in bounding the performance envelope of ignition targets. This paper describes an experiment for ablative RT instability that for the first time achieves growth factors close to those expected to occur in ignition targets at the National Ignition Facility (NIF). The large growth allows small seed perturbations to be detected and can be used to place an upper bound on perturbation growth at the ablation front resulting from microstructure in the preferred Be ablator. The experiments were performed on the Omega laser using a halfraum 1.2 mm long by 2 mm diameter with a 75% laser entrance hole. The halfraum was filled with {approx} 1 atm of neopentane to delay gold plasma from closing the diagnostic line of sight down the axis of the halfraum. The ablator was mounted at the base of the halfraum, and was accelerated by a two stepped X-ray pulse consisting of an early time section {approx} 100 eV to emulate the NIF foot followed by an approximately constant {approx} 150 eV drive sustained over an additional 5-7ns. It is this long pulse duration and late time observation that distinguishes the present work from previous experiments, and is responsible for the large growth that is achieved. The growth of a 2D sinusoidal perturbation machined on the drive side of the ablator was measured using face-on radiography. The diagnostic view remained open until {approx} 11 ns with maximum growth factors measured to be {approx} 200. The trajectory of the ablator was measured using streaked backlit radiography. The design and analysis of the experiments is described, and implications for experiments on ignition target ablators are discussed.
RAYLEIGH-TAYLOR INSTABILITY IN PARTIALLY IONIZED COMPRESSIBLE PLASMAS
Diaz, A. J.; Ballester, J. L. E-mail: roberto.soler@wis.kuleuven.be
2012-07-20
We study the modification of the classical criterion for the linear onset and growing rate of the Rayleigh-Taylor instability (RTI) in a partially ionized plasma in the two-fluid description. The plasma is composed of a neutral fluid and an electron-ion fluid, coupled by means of particle collisions. The governing linear equations and appropriate boundary conditions, including gravitational terms, are derived and applied to the case of the RTI in a single interface between two partially ionized plasmas. The limits of collisionless, no gravity, and incompressible fluids are checked before addressing the general case. We find that both compressibility and ion-neutral collisions lower the linear growth rate, but do not affect the critical threshold of the onset of the RTI. The configuration is always unstable when a lighter plasma is below a heavier plasma regardless the value of the magnetic field strength, the ionization degree, and the ion-neutral collision frequency. However, ion-neutral collisions have a strong impact on the RTI growth rate, which can be decreased by an order of magnitude compared to the value in the collisionless case. Ion-neutral collisions are necessary to accurately describe the evolution of the RTI in partially ionized plasmas such as prominences. The timescale for the development of the instability is much longer than in the classical incompressible fully ionized case. This result may explain the existence of prominence fine structures with life times of the order of 30 minutes. The timescales derived from the classical theory are about one order of magnitude shorter and incompatible with the observed life times.
Classical Rayleigh-Taylor Instability Experiments at Nova
NASA Astrophysics Data System (ADS)
Budil, Kimberly S.
1997-11-01
Hydrodynamic instabilities impact a wide range of physical systems, from inertial confinement fusion (ICF) capsules to supernovae. The ICF community has devoted a great deal of effort to understanding the development of instabilities at an ablation front, where the shortest wavelengths are predicted to be stabilized. We(in collaboration with B. A. Remington, S. V. Weber, T. A. Peyser, and T. S. Perry) have performed a series of experiments investigating the evolution of the Rayleigh-Taylor instability at an embedded, or classical, interface. Without the stabilizing influence of ablation, short wavelengths should grow strongly and behavior in the deep nonlinear regime of growth should be accesible. This strong growth of short wavelengths allows us to study the interaction of multiple modes superposed at the embedded interface. As the growth proceeds, the modes will begin to couple and it is predicted that an inverse cascade will occur, with progressively larger structures dominating the flow. In our initial experiments a single mode perturbation placed at the interface between a brominated plastic ablator and a titanium payload was studied. These results were compared to the growth of similar perturbations placed at an ablation front to conclusively demonstrate the effect of ablative stabilization. Subsequent experiments were devoted to the study of a superposition of 2, 10, or 20 modes to observe the effects of mode coupling and bubble competition processes. The technique was also extended to the study of two modes initially below the experimental resolution which were diagnosed by the appearance of the longer-wavelength coupled mode, demonstrating the technique of ``subresolution imaging''. Recent experiments have attempted to observe the process of bubble competition directly, by placing a pattern of alternating small and large bubbles at the interface and watching the evolution of the smaller bubble relative to its larger neighbor.
Boundary selection of stable wavenumbers in Taylor-vortex flow.
NASA Astrophysics Data System (ADS)
Linek, Marcus; Ahlers, Guenter
1996-11-01
Non-rotating rigid ends in Taylor-vortex flow (TVF) with a rotating inner and stationary outer cylinder produce large-amplitude Ekman vortices which pin the phase of the pattern. The band of stable wavenumbers is then limited by a bulk instability, namely the Eckhaus instability. For small ɛ, this leads to a stable wavenumber band of order ɛ ^1/2 where ɛ ≡ (f - f_c)/fc with f the inner-cylinder speed and fc the value of f for the onset of TVF. When one of the ends of a vertical TVF system has a free surface, the vortex amplitude adjacent to this surface is considerably reduced and the phase pinning is weaker. Experimentally we find that this can lead to a different instability mechanism consisting of losses or gains of vortices at the free boundary. This mechanism yields a more narrow wavenumber band of order ɛ, as predicted by Cross et al.^1 Specifically we find that TVF is stable for wavenumbers k over the range λ- ɛ < (k - k_c)/kc < λ+ ɛ where kc is the value of k at onset. We find that λ - ~= - 0.55 and λ + ~= 0.70 in a system with a radius ratio η = 0.75. A detailed calculation of λ_+,- would be most interesting. Supported by NSF Grant No. DMR94-19168, and by the Deutsche Agentur für Raumfahrtangelegenheiten (DARA).l ^1 M.C. Cross, P.G. Daniels, P.C. Hohenberg, and E.D. Siggia, J. Fluid Mech.127, 155 (1983).
Authority in Educational Relationships.
ERIC Educational Resources Information Center
Steutel, Jan; Spiecker, Ben
2000-01-01
Summarizes John Wilson's account of authority in educational relationships by reconstructing his views on different types of authority. Explores the topic of parental authority arguing that parental authority differs from the authority of teachers. Comments on whether authoritative parental supervision is essential. Includes references. (CMK)
Sasaki, Kazuki; Suzuki, Naoya; Saito, Hiroki; Akamatsu, Daisuke
2009-12-15
The Rayleigh-Taylor instability at the interface in an immiscible two-component Bose-Einstein condensate is investigated using the mean field and Bogoliubov theories. Rayleigh-Taylor fingers are found to grow from the interface and mushroom patterns are formed. Quantized vortex rings and vortex lines are then generated around the mushrooms. The Rayleigh-Taylor instability and mushroom-pattern formation can be observed in a trapped system.
1999-06-01
STUDY OF COLLIDING-SHELL CONFIGURATIONS TO REDUCE THE EFFECTS OF MAGNETIC RAYLEIGH -TAYLOR ON IMPLODING LINERS R.J. Faehl, W.L. Atchison, R.K...colliding shell configurations to mitigate the effects of Magnetic Rayleigh -Taylor (MRT) on the inner liner. Two-dimensional MHD calculations of liners have...computational study will be presented. I. INTRODUCTION This study examined the effect of colliding shell interactions on unstable Magnetic Rayleigh -Taylor
Liao, Bolin; Zhang, Yunong; Jin, Long
2016-02-01
In this paper, a new Taylor-type numerical differentiation formula is first presented to discretize the continuous-time Zhang neural network (ZNN), and obtain higher computational accuracy. Based on the Taylor-type formula, two Taylor-type discrete-time ZNN models (termed Taylor-type discrete-time ZNNK and Taylor-type discrete-time ZNNU models) are then proposed and discussed to perform online dynamic equality-constrained quadratic programming. For comparison, Euler-type discrete-time ZNN models (called Euler-type discrete-time ZNNK and Euler-type discrete-time ZNNU models) and Newton iteration, with interesting links being found, are also presented. It is proved herein that the steady-state residual errors of the proposed Taylor-type discrete-time ZNN models, Euler-type discrete-time ZNN models, and Newton iteration have the patterns of O(h(3)), O(h(2)), and O(h), respectively, with h denoting the sampling gap. Numerical experiments, including the application examples, are carried out, of which the results further substantiate the theoretical findings and the efficacy of Taylor-type discrete-time ZNN models. Finally, the comparisons with Taylor-type discrete-time derivative model and other Lagrange-type discrete-time ZNN models for dynamic equality-constrained quadratic programming substantiate the superiority of the proposed Taylor-type discrete-time ZNN models once again.
Fortieth Lauriston S. Taylor Lecture: Radiation Protection and Regulatory Science.
Poston, John W
2017-02-01
It took about 30 y after Wilhelm Konrad Roentgen's discovery of x rays and Henri Becquerel's discovery of natural radioactivity for scientists in the civilized world to formulate recommendations on exposure to ionizing radiation. We know of these efforts today because the organizations that resulted from the concerns raised in 1928 at the Second International Congress of Radiology still play a role in radiation protection. The organizations are known today as the International Commission on Radiological Protection and, in the United States, the National Council on Radiation Protection and Measurements (NCRP). Today, as we have many times in the past, we honor Dr. Lauriston Sale Taylor, the U.S. representative to the 1928 Congress, for his dedication and leadership in the early growth of NCRP. NCRP's mission is "to support radiation protection by providing independent scientific analysis, information, and recommendations that represent the consensus of leading scientists." The developments in science and technology, including radiation protection, are occurring so rapidly that NCRP is challenged to provide its advice and guidance at a faster pace than ever before. NCRP's role has also expanded as the Council considers newer uses and applications of ionizing radiation in research and medicine as well as the response to nuclear or radiological terrorism. In such a technical world, new areas have been established to deal with the nexus of science and regulation, especially in the United States. Lord Ernest Rutherford supposedly said, "That which is not measurable is not science. That which is not physics is stamp collecting." I wonder what he would say if he were alive today as now many embrace a new field called "regulatory science." This term was suggested by Professor Mitsuru Uchiyama in Japan in 1987 and was reviewed in literature published in English in 1996. Some have attributed a similar idea to Dr. Alvin Weinberg, for many years Director of the Oak Ridge
Velocity and magnetic field measurements of Taylor plumes in SSX under different boundary conditions
NASA Astrophysics Data System (ADS)
Kaur, Manjit; Brown, M. R.; Han, J.; Shrock, J. E.; Schaffner, D. A.
2016-10-01
The SSX device has been modified by the addition of a 1 m long glass extension for accommodating pulsed theta pinch coils. The Taylor plumes are launched from a magnetized plasma gun and flow to an expansion volume downstream. The time of flight (TOF) measurements of these plumes are carried out using a linear array of Ḃ probes (separated by 10cm). TOF of the plasma plumes from one probe location to the next is determined by direct comparison of the magnetic field structures as well as by carrying out a cross-correlation analysis. With the glass boundary, the typical velocity of the Taylor plumes is found to be 25km /s , accompanied by a fast plasma (>= 50km /s) at the leading edge. Magnetic field embedded in the Taylor plumes is measured in the expansion chamber using a three-dimensional array of Ḃ probes and is found to be 700G . Some flux conservation of the Taylor plumes is provided by using a resistive (soak time 3 μs) and a mesh (soak time 170 μs > discharge time) liner around the glass tube for improving the downstream Taylor state velocity as well as the magnetic field. The results from these different boundary conditions will be presented. Work supported by DOE OFES and ARPA-E ALPHA programs.
Bubbly drag reduction in a vertical Couette-Taylor system with superimposed axial flow
NASA Astrophysics Data System (ADS)
Maryami, R.; Farahat, S.; Javad poor, M.; Shafiei Mayam, M. H.
2014-10-01
The effect of axial flow on bubbly drag reduction has been experimentally investigated in a vertical Couette-Taylor flow system. The water flow is combined from circumferential and axial flow. Flow condition is fully turbulence and Taylor vortices have appeared in the annulus gap. The shear stress modification in the simultaneous presence of air bubbles and axial flow in the system has been studied by measuring torque acting on the inner cylinder. The results show that axial flow improves the effect of bubbles on drag reduction by damping Taylor vortices and increasing upward velocity of bubbles. In this case, drag reduction of more than 25% has been achieved, which corresponds to lower tested {{\\operatorname{Re}}_{\\omega }} and this amount is gradually decreased with increasing {{\\operatorname{Re}}_{\\omega }} in each {{\\operatorname{Re}}_{a}} and {{Q}_{a}}. Increasing {{Q}_{a}} causes drag reduction enhancement which could be due to the effect of bubbles on flow density reduction, flow fluctuations and Taylor vortices. Moreover, it is observed that skin friction is affected by axial flow solely and by increasing its volume rates, drag reduction reaches 11%. It is concluded that when bubbles and axial flow are simultaneously applied into the Couette-Taylor flow, the amount of achieved drag reduction is more than when they are separately applied.
Reconnaissance and deep-drill site selection on Taylor Dome, Antarctica
NASA Technical Reports Server (NTRS)
Grootes, Pieter M.; Waddington, Edwin D.
1993-01-01
Taylor Dome is a small ice dome near the head of Taylor Valley, Southern Victoria Land. The location of the dome, just west of the Transantarctic Mountains, is expected to make the composition of the accumulating snow sensitive to changes in the extent of the Ross Ice Shelf. Thus, it is linked to the discharge of the West Antarctic Ice Sheet but protected against direct influences of glacial-interglacial sea-level rise. The record of past climatic and environmental changes in the ice provides a valuable complement to the radiocarbon-dated proxy record of climate derived from perched deltas, strandlines, and moraines that have been obtained in the nearby Dry Valleys. We carried out a reconnaissance of the Taylor Dome area over the past two field seasons to determine the most favorable location to obtain a deep core to bedrock. A stake network has been established with an 80-km line roughly along the crest of Taylor Dome, and 40-km lines parallel to it and offset by 10 km. These lines have been surveyed 1990/91, and the positions of 9 grid points have been determined with geoceivers. A higher density stake network was placed and surveyed around the most likely drill area in the second year. Ground-based radar soundings in both years provided details on bedrock topography and internal layering of the ice in the drill area. An airborne radar survey in January 1992, completed the radar coverage of the Taylor Dome field area.
Reconnaissance and deep-drill site selection on Taylor Dome, Antarctica
NASA Technical Reports Server (NTRS)
Grootes, Pieter M.; Waddington, Edwin D.
1993-01-01
Taylor Dome is a small ice dome near the head of Taylor Valley, Southern Victoria Land. The location of the dome, just west of the Transantarctic Mountains, is expected to make the composition of the accumulating snow sensitive to changes in the extent of the Ross Ice Shelf. Thus, it is linked to the discharge of the West Antarctic Ice Sheet but protected against direct influences of glacial-interglacial sea-level rise. The record of past climatic and environmental changes in the ice provides a valuable complement to the radiocarbon-dated proxy record of climate derived from perched deltas, strandlines, and moraines that have been obtained in the nearby Dry Valleys. We carried out a reconnaissance of the Taylor Dome area over the past two field seasons to determine the most favorable location to obtain a deep core to bedrock. A stake network has been established with an 80-km line roughly along the crest of Taylor Dome, and 40-km lines parallel to it and offset by 10 km. These lines have been surveyed 1990/91, and the positions of 9 grid points have been determined with geoceivers. A higher density stake network was placed and surveyed around the most likely drill area in the second year. Ground-based radar soundings in both years provided details on bedrock topography and internal layering of the ice in the drill area. An airborne radar survey in January 1992, completed the radar coverage of the Taylor Dome field area.
Brock, Billy C.
2008-03-01
Application of Taylor weighting (taper) to an antenna aperture can achieve low peak sidelobes, but combining the Taylor weighting with quantized attenuators and phase shifters at each radiating element will impact the performance of a phased-array antenna. An examination of array performance is undertaken from the simple point of view of the characteristics of the array factor. Design rules and guidelines for determining the Taylor-weighting parameters, the number of bits required for the digital phase shifter, and the dynamic range and number of bits required for the digital attenuator are developed. For a radar application, when each element is fed directly from a transmit/receive module, the total power radiated by the array will be reduced as a result of the taper. Consequently, the issue of whether to apply the taper on both transmit and receive configurations, or only on the receive configuration is examined with respect to two-way sidelobe performance.
Process development of starch hydrolysis using mixing characteristics of Taylor vortices.
Masuda, Hayato; Horie, Takafumi; Hubacz, Robert; Ohmura, Naoto; Shimoyamada, Makoto
2017-04-01
In food industries, enzymatic starch hydrolysis is an important process that consists of two steps: gelatinization and saccharification. One of the major difficulties in designing the starch hydrolysis process is the sharp change in its rheological properties. In this study, Taylor-Couette flow reactor was applied to continuous starch hydrolysis process. The concentration of reducing sugar produced via enzymatic hydrolysis was evaluated by varying operational variables: rotational speed of the inner cylinder, axial velocity (reaction time), amount of enzyme, and initial starch content in the slurry. When Taylor vortices were formed in the annular space, efficient hydrolysis occurred because Taylor vortices improved the mixing of gelatinized starch with enzyme. Furthermore, a modified inner cylinder was proposed, and its mixing performance was numerically investigated. The modified inner cylinder showed higher potential for enhanced mixing of gelatinized starch and the enzyme than the conventional cylinder.
Exploring the phase space of multiple states in highly turbulent Taylor-Couette flow
NASA Astrophysics Data System (ADS)
van der Veen, Roeland C. A.; Huisman, Sander G.; Dung, On-Yu; Tang, Ho L.; Sun, Chao; Lohse, Detlef
2016-06-01
We investigate the existence of multiple turbulent states in highly turbulent Taylor-Couette flow in the range of Ta =1011 to 9 ×1012 by measuring the global torques and the local velocities while probing the phase space spanned by the rotation rates of the inner and outer cylinders. The multiple states are found to be very robust and are expected to persist beyond Ta =1013 . The rotation ratio is the parameter that most strongly controls the transitions between the flow states; the transitional values only weakly depend on the Taylor number. However, complex paths in the phase space are necessary to unlock the full region of multiple states. By mapping the flow structures for various rotation ratios in a Taylor-Couette setup with an equal radius ratio but a larger aspect ratio than before, multiple states are again observed. Here they are characterized by even richer roll structure phenomena, including an antisymmetrical roll state.
Vortices and Particle-banding in Granular Taylor-Couette Flow
NASA Astrophysics Data System (ADS)
Mahajan, Achal; Alam, Meheboob
2016-11-01
A collection of smooth inelastic hard spheres is simulated between two rotating concentric cylinders, dubbed granular Taylor-Couette flow (gTCF), using event-driven molecular dynamics simulations. The inner cylinder is rotating with rotational speed ωi and the outer cylinder is kept stationary in the absence of gravity. The onset of Taylor-like vortices is studied as functions of the inner rotation ωi, the restitution coefficient (en) and the aspect ratio of the cylinder. The strength of vortices is found to decrease with increasing dissipation. A novel banding-pattern of particle-rich and particle-depleted regions along the axial direction is found - the density-contrast between the dense and dilute regions increases with decreasing restitution coefficient. The combined effect of inelastic dissipation and compressibility seems to be responsible for the genesis of Taylor-like vortices with axial-banding of particles.
Short-time Lyapunov exponent analysis and the transition to chaos in Taylor-Couette flow
NASA Technical Reports Server (NTRS)
Vastano, John A.; Moser, Robert D.
1991-01-01
The physical mechanism driving the weakly chaotic Taylor-Couette flow is investigated using the short-time Liapunov exponent analysis. In this procedure, the transition from quasi-periodicity to chaos is studied using direct numerical 3D simulations of axially periodic Taylor-Couette flow, and a partial Liapunov exponent spectrum for the flow is computed by simultaneously advancing the full solution and a set of perturbations. It is shown that the short-time Liapunov exponent analysis yields more information on the exponents and dimension than that obtained from the common Liapunov exponent calculations. Results show that the chaotic state studied here is caused by a Kelvin-Helmholtz-type instability of the outflow boundary jet of Taylor vortices.
Large eddy simulation of Rayleigh-Taylor instability using the arbitrary Lagrangian-Eulerian method
NASA Astrophysics Data System (ADS)
Darlington, Rebecca Mattson
This research addresses the application of a large eddy simulation (LES) to Arbitrary Lagrangian Eulerian (ALE) simulations of Rayleigh-Taylor instability. First, ALE simulations of simplified Rayleigh-Taylor instability are studied. The advantages of ALE over Eulerian simulations are shown. Next, the behavior of the LES is examined in a more complicated ALE simulation of Rayleigh-Taylor instability. The effects of eddy viscosity and stochastic backscatter are examined. The LES is also coupled with ALE to increase grid resolution in areas where it is needed. Finally, the methods studied above are applied to two sets of experimental simulations. In these simulations, ALE allows the mesh to follow expanding experimental targets, while LES can be used to mimic the effect of unresolved instability modes.
The evolution equations for Taylor vortices in the small gap limit
NASA Technical Reports Server (NTRS)
Hall, P.
1983-01-01
The centrifugal instability of the viscous fluid flow between concentric circular cylinders in the small gap limit is considered. The amplitude of the Taylor vortex is allowed to depend on a slow time variable, a slow axial variable, and the polar angle. It is shown that the amplitude of the vortex cannot in general be described by a single amplitude equation. However, if the axial variations are periodic a single amplitude equation can be derived. In the absence of any slow axial variations it is shown that a Taylor vortex remains stable to wavy vortex perturbations. Furthermore, in this situation, stable nonaxisymmetric modes can occur but do not bifurcate from the Taylor vortex state. The stability of these modes is shown to be governed by a modified form of the Eckhaus criterion.
Growth rate of Rayleigh-Taylor turbulent mixing layers with the foliation approach.
Poujade, Olivier; Peybernes, Mathieu
2010-01-01
For years, astrophysicists, plasma fusion, and fluid physicists have puzzled over Rayleigh-Taylor turbulent mixing layers. In particular, strong discrepancies in the growth rates have been observed between experiments and numerical simulations. Although two phenomenological mechanisms (mode-coupling and mode-competition) have brought some insight on these differences, convincing theoretical arguments are missing to explain the observed values. In this paper, we provide an analytical expression of the growth rate compatible with both mechanisms and is valid for a self-similar, low Atwood Rayleigh-Taylor turbulent mixing subjected to a constant or time-varying acceleration. The key step in this work is the presentation of foliated averages and foliated turbulent spectra highlighted in our three-dimensional numerical simulations. We show that the exact value of the Rayleigh-Taylor growth rate not only depends upon the acceleration history but is also bound to the power-law exponent of the foliated spectra at large scales.
Growth rate of Rayleigh-Taylor turbulent mixing layers with the foliation approach
Poujade, Olivier; Peybernes, Mathieu
2010-01-15
For years, astrophysicists, plasma fusion, and fluid physicists have puzzled over Rayleigh-Taylor turbulent mixing layers. In particular, strong discrepancies in the growth rates have been observed between experiments and numerical simulations. Although two phenomenological mechanisms (mode-coupling and mode-competition) have brought some insight on these differences, convincing theoretical arguments are missing to explain the observed values. In this paper, we provide an analytical expression of the growth rate compatible with both mechanisms and is valid for a self-similar, low Atwood Rayleigh-Taylor turbulent mixing subjected to a constant or time-varying acceleration. The key step in this work is the presentation of foliated averages and foliated turbulent spectra highlighted in our three-dimensional numerical simulations. We show that the exact value of the Rayleigh-Taylor growth rate not only depends upon the acceleration history but is also bound to the power-law exponent of the foliated spectra at large scales.
Short-time Lyapunov exponent analysis and the transition to chaos in Taylor-Couette flow
NASA Technical Reports Server (NTRS)
Vastano, John A.; Moser, Robert D.
1991-01-01
The physical mechanism driving the weakly chaotic Taylor-Couette flow is investigated using the short-time Liapunov exponent analysis. In this procedure, the transition from quasi-periodicity to chaos is studied using direct numerical 3D simulations of axially periodic Taylor-Couette flow, and a partial Liapunov exponent spectrum for the flow is computed by simultaneously advancing the full solution and a set of perturbations. It is shown that the short-time Liapunov exponent analysis yields more information on the exponents and dimension than that obtained from the common Liapunov exponent calculations. Results show that the chaotic state studied here is caused by a Kelvin-Helmholtz-type instability of the outflow boundary jet of Taylor vortices.
Investigation of Taylor bubble wake structure in liquid nitrogen by PIV technique
NASA Astrophysics Data System (ADS)
Liu, Yi-Peng; Wang, Ping-Yang; Wang, Jing; Du, Zhao-Hui
2013-05-01
The Taylor bubble wake structures of liquid nitrogen in circular tubes with five different inner diameters under various inclination angles were investigated using particle image velocimetry (PIV) technique. Optical distortions produced by tube curvature and the refractive index difference between the tube and fluid were corrected by a new correction algorithm, which requires fewer equations than the existing one. The uniform grid validation shows the maximum error of the developed algorithm is only 3%. Experimental results have shown that the criterion for determining the wake structure of Taylor bubble in normal atmospheric temperature fluid in vertical tube from reference is still applicable for liquid nitrogen at higher Eötvös numbers 173 and 226; but the criterion is no longer applicable when the Eötvös numbers are at lower values of 8, 22 and 57. For the inclined tube, the vortex size in Taylor bubble wake was found to increase with the decreasing of inclination angle.
Rayleigh-Taylor instability of crystallization waves at the superfluid-solid 4He interface.
Burmistrov, S N; Dubovskii, L B; Tsymbalenko, V L
2009-05-01
At the superfluid-solid 4He interface there exist crystallization waves having much in common with gravitational-capillary waves at the interface between two normal fluids. The Rayleigh-Taylor instability is an instability of the interface which can be realized when the lighter fluid is propelling the heavier one. We investigate here the analogs of the Rayleigh-Taylor instability for the superfluid-solid 4He interface. In the case of a uniformly accelerated interface the instability occurs only for a growing solid phase when the magnitude of the acceleration exceeds some critical value independent of the surface stiffness. For the Richtmyer-Meshkov limiting case of an impulsively accelerated interface, the onset of instability does not depend on the sign of the interface acceleration. In both cases the effect of crystallization wave damping is the reduction in the perturbation growth rate of the Taylor unstable interface.
NASA Astrophysics Data System (ADS)
Leahy, Brian; Ong, Desmond; Cheng, Xiang; Cohen, Itai
2013-03-01
The idea of Taylor dispersion - enhancement of translational diffusion under shear - has found applications in fields from pharmacology to chemical engineering. Here, in a combination of experiment and simulations, we study the translational and rotational diffusion of colloidal dimers under triangle-wave oscillatory shear. We find that the rotational diffusion is enhanced, in addition to the enhanced translational diffusion. This ``rotational Taylor dispersion'' depends strongly on the strain rate (Peclet number), aspect ratio, and the shear strain, in contradistinction to translational Taylor dispersion in a shear flow, which depends only weakly on strain rate and aspect ratio. This separate tunability of translations and orientations promises important applications in mixing and self-assembly of solutions of anisometric colloids. We discuss the corresponding effect on the structure and rheology of denser suspensions of rod-like particles. B. L. acknowledges supported by the Department of Defense (DoD) through the National Defense Science & Engineering Graduate Fellowship (NDSEG) Program.
A modified Taylor rule for dealing with demand shocks and uncertain potential macroeconomic output
NASA Astrophysics Data System (ADS)
Alvarez-Ramirez, Jose; Ibarra-Valdez, Carlos; Fernandez-Anaya, Guillermo; Villarreal, Francisco
2008-02-01
A critical issue for central banks in modern economies is the inflation stabilization about a prescribed level. The best-known simple instrumental rule to guide monetary policy to control inflation is the Taylor rule, where the instrument (e.g., a short interest rate) responds to changes in the inflation and the output gaps. The objective of this paper is to introduce some modifications to the Taylor rule in order to improve its robustness with respect to uncertainties about potential output and unanticipated shocks. To this end, departing from feedback control theory, the Taylor rule is equipped with an adaptive control scheme to reject the adverse effects of shocks and to estimate the deviations of the potential output. It is shown that the proposed adaptation procedure is equivalent to a classical integral feedback controller whose characteristics and implementation issues are well understood in practical control engineering. Singular perturbation methods are used to establish the stability properties of the resulting control system.
Large eddy simulation of Rayleigh-Taylor instability using the arbitrary Lagrangian-Eulerian method
Darlington, Rebecca Mattson
1999-12-01
This research addresses the application of a large eddy simulation (LES) to Arbitrary Lagrangian Eulerian (ALE) simulations of Rayleigh-Taylor instability. First, ALE simulations of simplified Rayleigh-Taylor instability are studied. The advantages of ALE over Eulerian simulations are shown. Next, the behavior of the LES is examined in a more complicated ALE simulation of Rayleigh-Taylor instability. The effects of eddy viscosity and stochastic backscatter are examined. The LES is also coupled with ALE to increase grid resolution in areas where it is needed. Finally, the methods studied above are applied to two sets of experimental simulations. In these simulations, ALE allows the mesh to follow expanding experimental targets, while LES can be used to mimic the effect of unresolved instability modes.
Tweedie convergence: A mathematical basis for Taylor's power law, 1/f noise, and multifractality
NASA Astrophysics Data System (ADS)
Kendal, Wayne S.; Jørgensen, Bent
2011-12-01
Plants and animals of a given species tend to cluster within their habitats in accordance with a power function between their mean density and the variance. This relationship, Taylor's power law, has been variously explained by ecologists in terms of animal behavior, interspecies interactions, demographic effects, etc., all without consensus. Taylor's law also manifests within a wide range of other biological and physical processes, sometimes being referred to as fluctuation scaling and attributed to effects of the second law of thermodynamics. 1/f noise refers to power spectra that have an approximately inverse dependence on frequency. Like Taylor's law these spectra manifest from a wide range of biological and physical processes, without general agreement as to cause. One contemporary paradigm for 1/f noise has been based on the physics of self-organized criticality. We show here that Taylor's law (when derived from sequential data using the method of expanding bins) implies 1/f noise, and that both phenomena can be explained by a central limit-like effect that establishes the class of Tweedie exponential dispersion models as foci for this convergence. These Tweedie models are probabilistic models characterized by closure under additive and reproductive convolution as well as under scale transformation, and consequently manifest a variance to mean power function. We provide examples of Taylor's law, 1/f noise, and multifractality within the eigenvalue deviations of the Gaussian unitary and orthogonal ensembles, and show that these deviations conform to the Tweedie compound Poisson distribution. The Tweedie convergence theorem provides a unified mathematical explanation for the origin of Taylor's law and 1/f noise applicable to a wide range of biological, physical, and mathematical processes, as well as to multifractality.
NASA Astrophysics Data System (ADS)
Couque, Hervé
2015-09-01
Taylor tests are a mean to investigate the dynamic plastic and failure behaviour of metals under compression. By taking in account the strengthening occurring at high strain rates, the Taylor final diameter of a pure nickel impacted at 453 m/s have been numerically reproduced by 13%. Through post-mortem observations of the specimen impacted at 453 m/s, a recrystallization process has been found to occur resulting in a softening of the pure nickel. Subsequent numerical simulations taking in account this softening have been found to reduce the difference between experimental and numerical diameter by 10%.
Study of Rayleigh-Taylor growth in directly driven cryogenic-deuterium targets
Hager, J. D.; Hu, S. X.; Knauer, J. P.; Meyerhofer, D. D.; Sangster, T. C.; Smalyuk, V. A.
2012-07-15
Direct-drive, Rayleigh-Taylor growth experiments in liquid deuterium (D{sub 2}) were performed on the OMEGA laser [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] using planar cryogenic targets at a laser intensity of {approx}4 Multiplication-Sign 10{sup 14} W/cm{sup 2}. These are the first Rayleigh-Taylor measurements in deuterium at conditions relevant to inertial confinement fusion using a mass preimposed initial modulation. The measured modulation optical depths are in agreement with the 2D hydrodynamics code DRACO using flux-limited local thermal transport, providing an important step in the experimental validation of simulations for direct-drive ignition.
Toward analytic theory of the Rayleigh-Taylor instability: lessons from a toy model
NASA Astrophysics Data System (ADS)
Mailybaev, Alexei A.
2017-06-01
In this work we suggest that a turbulent phase of the Rayleigh-Taylor instability can be explained as a universal stochastic wave traveling with constant speed in a properly renormalized system. This wave, originating from ordinary deterministic chaos in a renormalized time, has two constant limiting states at both sides. These states are related to the initial discontinuity at large scales and to stationary turbulence at small scales. The theoretical analysis is confirmed with extensive numerical simulations made for a new shell model, which features basic properties of the phenomenological theory for the Rayleigh-Taylor instability.
NASA Astrophysics Data System (ADS)
Wu, Qian
2015-09-01
Using the National Center for Atmospheric Research Thermosphere Ionosphere Electrodynamics General Circulation Model (TIEGCM), the ionospheric Rayleigh-Taylor instability growth rate is calculated. The seasonal and longitudinal variations of the growth rate from the TIEGCM appear to match that of the spread F observed by various satellite missions. The growth rate is strongly dependent on the angle between the sunset terminator and the geomagnetic field line near the magnetic equator. The TIEGCM simulations with nonmigrating tides show the zonal wave number 4 structure in the Rayleigh-Taylor instability due to the inclusion of the nonmigrating diurnal eastward zonal wave number 3 and semidiurnal eastward zonal wave number 2 tides.
Corrections to the theory and the optimal line in the swimming diagram of Taylor (1952).
Humphrey, Joseph A C; Chen, Jun; Iwasaki, Tetsuya; Friesen, W Otto
2010-08-06
The analysis of undulatory swimming gaits requires knowledge of the fluid forces acting on the animal body during swimming. In his classical 1952 paper, Taylor analysed this problem using a 'resistive-force' theory. The theory was used to characterize the undulatory gaits that result in the smallest energy dissipation to the fluid for a given swim velocity. The optimal gaits thus found were compared with data recorded from movies of a snake and a leech swimming. This report identifies and corrects a mathematical error in Taylor's paper, showing that his theory applies even better to animals of circular cross section.
A Variational Approach to the Rayleigh-Taylor Instability of an Accelerating Plasma Slab.
1981-12-01
William Strutt . Scientific Papers. New York: Dover. 1964. 16. Reid, W. H. and Harris, D. L. "On Orthogonal Func- tions which Satisfy Four Boundary...AD-AL18 074 AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOO -ETC P 5 18/3 VARIATIONAL APPROACH TO THE RAYLEIGH -TAYLOR INSTABILITY OF AN--ETC(U...16, Yl4~ ’.~t~ -’ - -~ ~ r dmA ak -’I t. 4 Ar * 1- ______Z"__7 AFI/GEP/PH/81D-11 A VARIATIONAL APPROACH TO0 TE RAYLEIGH -TAYLOR INSTABILITY OF
Magnetic field generation by the Rayleigh-Taylor instability in laser-driven planar plastic targets.
Gao, L; Nilson, P M; Igumenschev, I V; Hu, S X; Davies, J R; Stoeckl, C; Haines, M G; Froula, D H; Betti, R; Meyerhofer, D D
2012-09-14
Magnetic fields generated by the Rayleigh-Taylor instability were measured in laser-accelerated planar foils using ultrafast proton radiography. Thin plastic foils were irradiated with ∼4-kJ, 2.5-ns laser pulses focused to an intensity of ∼10(14) W/cm(2) on the OMEGA EP Laser System. Target modulations were seeded by laser nonuniformities and amplified during target acceleration by the Rayleigh-Taylor instability. The experimental data show the hydrodynamic evolution of the target and MG-level magnetic fields generated in the broken foil. The experimental data are in good agreement with predictions from 2-D magnetohydrodynamic simulations.
Suppressing the Rayleigh-Taylor instability with a rotating magnetic field.
Rannacher, Dirk; Engel, Andreas
2007-01-01
The Rayleigh-Taylor instability of a magnetic fluid superimposed on a nonmagnetic liquid of lower density may be suppressed with the help of a spatially homogeneous magnetic field rotating in the plane of the undisturbed interface. Starting from the complete set of Navier-Stokes equations for both liquids a Floquet analysis is performed which consistently takes into account the viscosities of the fluids. Using experimentally relevant values of the parameters we suggest to use this stabilization mechanism to provide controlled initial conditions for an experimental investigation of the Rayleigh-Taylor instability.
Masse, L; Casner, A; Galmiche, D; Huser, G; Liberatore, S; Theobald, M
2011-05-01
A laminated ablator is explored as an alternative concept for stabilizing the ablative Rayleigh-Taylor instability which develops in inertial fusion targets. Experiments measuring the growth of the Rayleigh-Taylor instability of laminated planar foils are reported. Consistent with both theory and simulations, a significant reduction of the perturbation growth is experimentally observed for laminated ablators in comparison to what is observed for classical uniform ablators. Such an enhanced hydrodynamic stability opens opportunities for the design of high-gain inertial fusion targets. © 2011 American Physical Society
Masse, L.; Casner, A.; Galmiche, D.; Huser, G.; Liberatore, S.; Theobald, M.
2011-05-15
A laminated ablator is explored as an alternative concept for stabilizing the ablative Rayleigh-Taylor instability which develops in inertial fusion targets. Experiments measuring the growth of the Rayleigh-Taylor instability of laminated planar foils are reported. Consistent with both theory and simulations, a significant reduction of the perturbation growth is experimentally observed for laminated ablators in comparison to what is observed for classical uniform ablators. Such an enhanced hydrodynamic stability opens opportunities for the design of high-gain inertial fusion targets.
Suppression of the Rayleigh-Taylor instability due to self-radiation in a multiablation target.
Fujioka, Shinsuke; Sunahara, Atsushi; Nishihara, Katsunobu; Ohnishi, Naofumi; Johzaki, Tomoyuki; Shiraga, Hiroyuki; Shigemori, Keisuke; Nakai, Mitsuo; Ikegawa, Tadashi; Murakami, Masakatsu; Nagai, Keiji; Norimatsu, Takayoshi; Azechi, Hiroshi; Yamanaka, Tatsuhiko
2004-05-14
A scheme to suppress the Rayleigh-Taylor instability has been investigated for a direct-drive inertial fusion target. In a high-Z doped-plastic target, two ablation surfaces are formed separately-one driven by thermal radiation and the other driven by electron conduction. The growth of the Rayleigh-Taylor instability is significantly suppressed on the radiation-driven ablation surface inside the target due to the large ablation velocity and long density scale length. A significant reduction of the growth rate was observed in simulations and experiments using a brominated plastic target. A new direct-drive pellet was designed using this scheme.
Viscous Rayleigh-Taylor instability experiments at high pressure and strain rate.
Park, Hye-Sook; Lorenz, K T; Cavallo, R M; Pollaine, S M; Prisbrey, S T; Rudd, R E; Becker, R C; Bernier, J V; Remington, B A
2010-04-02
Experimental results showing significant reductions from classical in the Rayleigh-Taylor instability growth rate due to high pressure effective lattice viscosity are presented. Using a laser created ramped drive, vanadium samples are compressed and accelerated quasi-isentropically at approximately 1 Mbar peak pressures, while maintaining the sample in the solid state. Comparisons with simulations and theory indicate that the high pressure, high strain rate conditions trigger a phonon drag mechanism, resulting in the observed high effective lattice viscosity and strong stabilization of the Rayleigh-Taylor instability.
Error estimate of Taylor's frozen-in flow hypothesis in the spectral domain
NASA Astrophysics Data System (ADS)
Narita, Yasuhito
2017-03-01
The quality of Taylor's frozen-in flow hypothesis can be measured by estimating the amount of the fluctuation energy mapped from the streamwise wavenumbers onto the Doppler-shifted frequencies in the spectral domain. For a random sweeping case with a Gaussian variation of the large-scale flow, the mapping quality is expressed by the error function which depends on the mean flow speed, the sweeping velocity, the frequency bin, and the frequency of interest. Both hydrodynamic and magnetohydrodynamic treatments are presented on the error estimate of Taylor's hypothesis with examples from the solar wind measurements.
Application of the Taylor transformation to the transient temperature response of an annular fin
Yu, L.T.; Chen, C.K.
1999-01-01
This article presents the transient temperature response of a convective-radiative rectangular profile annular fin under a step temperature change occurring in its base. A convection-radiation fin tip is considered. The nonlinear transient heat transfer and boundary conditions are solved by using the hybrid method of Taylor transformation and finite-difference approximation. Also, time domain is controlled by Taylor transformation, and the spatial coordinates are handled by finite-difference approximation. Temperature distribution is implemented by employing natural cubic spline fitting.
Patil, Amarjeet Dnyandeo; Bapat, Manasi; Patil, Sunita A.; Gogna, Roshan Lal
2015-01-01
The case history of a 35-year-old female patient with short stature is presented. She was posted for rectopexy in view of rectal prolapse. She was a known case of bronchial asthma. She had crowding of intervertebral spaces, which made administration of spinal anesthesia via the normal route very difficult. Taylor's approach for administration of the same was tried and proved successful, thus saving the patient from receiving general anesthesia in the presence of bronchial asthma, for a perineal surgery. The possible cause for the difficulty in administration of spinal anesthesia and the Taylor's approach are discussed, and reports of similar cases reviewed. PMID:26543472
Taylor Series Trajectory Calculations Including Oblateness Effects and Variable Atmospheric Density
NASA Technical Reports Server (NTRS)
Scott, James R.
2011-01-01
Taylor series integration is implemented in NASA Glenn's Spacecraft N-body Analysis Program, and compared head-to-head with the code's existing 8th- order Runge-Kutta Fehlberg time integration scheme. This paper focuses on trajectory problems that include oblateness and/or variable atmospheric density. Taylor series is shown to be significantly faster and more accurate for oblateness problems up through a 4x4 field, with speedups ranging from a factor of 2 to 13. For problems with variable atmospheric density, speedups average 24 for atmospheric density alone, and average 1.6 to 8.2 when density and oblateness are combined.
Alon, U.; Hecht, J.; Ofer, D.; Shvarts, D. Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 )
1995-01-23
The nonlinear evolution of large structure in Rayleigh-Taylor and Richtmyer-Meshkov bubble and spike fronts is studied numerically and explained theoretically on the basis of single-mode and two-bubble interaction physics at Atwood numbers ([ital A]). Multimode Rayleigh-Taylor bubble (spike) fronts are found as [ital h][sub [ital B
Code of Federal Regulations, 2011 CFR
2011-01-01
... to the former Liberian regime of Charles Taylor, pursuant to the International Emergency Economic... extraordinary threat to the foreign policy of the United States constituted by the actions and policies of..., and economic institutions and resources. The actions and policies of Charles Taylor and others...
ERIC Educational Resources Information Center
Stuart, Reginald
2011-01-01
When veteran educator Dr. N. Joyce Payne handed the reins of the organization she founded, the Thurgood Marshall College Fund, to entertainment lawyer and board member Johnny Taylor, Taylor began pursuing a remake of the prestigious group that has turned it on its head in just a matter of months. Today, with just more than a year of leading the…
ERIC Educational Resources Information Center
Stuart, Reginald
2011-01-01
When veteran educator Dr. N. Joyce Payne handed the reins of the organization she founded, the Thurgood Marshall College Fund, to entertainment lawyer and board member Johnny Taylor, Taylor began pursuing a remake of the prestigious group that has turned it on its head in just a matter of months. Today, with just more than a year of leading the…
Authority in Engineering Education
ERIC Educational Resources Information Center
Stephan, Karl D.
2012-01-01
Authority as a philosophical concept is defined both in general and as it applies to engineering education. Authority is shown to be a good and necessary part of social structures, in contrast to some cultural trends that regard it as an unnecessary and outmoded evil. Technical, educational, and organizational authority in their normal functions…
ERIC Educational Resources Information Center
Williams, Connie
2010-01-01
Over breakfast at the American Library Association (ALA) Annual Conference, this author was asked, "What is authority? What does one know about the ways in which he/she determines credibility? Whom do you trust?" In this article, the author focuses on these questions in terms of administrators who have control over libraries. She provides a…
ERIC Educational Resources Information Center
Locatis, Craig; Carr, Victor
1985-01-01
Presents suggestions for selecting authoring systems based on reviews of over one dozen systems; defines authoring systems; discusses their potential benefits; introduces background evaluation concepts; describes procedures for collecting information about system attributes; and presents a system selection checklist and an authoring system…
ERIC Educational Resources Information Center
Williams, Connie
2010-01-01
Over breakfast at the American Library Association (ALA) Annual Conference, this author was asked, "What is authority? What does one know about the ways in which he/she determines credibility? Whom do you trust?" In this article, the author focuses on these questions in terms of administrators who have control over libraries. She provides a…
Author! Author! Seymour Simon: Science Writer Extraordinaire
ERIC Educational Resources Information Center
Brodie, Carolyn S.
2005-01-01
This column presents a brief biography of author Seymour Simon, whose topics for children's photo essays include icebergs, gorillas, thunderstorms, optical illusions, snakes, air, water, planets, airplanes, volcanoes, cars, the brain, bridges, bugs, crocodiles, skyscrapers, sharks, and paper airplanes. Though he is best known in the style and an…
Author! Author! Seymour Simon: Science Writer Extraordinaire
ERIC Educational Resources Information Center
Brodie, Carolyn S.
2005-01-01
This column presents a brief biography of author Seymour Simon, whose topics for children's photo essays include icebergs, gorillas, thunderstorms, optical illusions, snakes, air, water, planets, airplanes, volcanoes, cars, the brain, bridges, bugs, crocodiles, skyscrapers, sharks, and paper airplanes. Though he is best known in the style and an…
Author! Author! Making Kids Laugh: Jon Scieszka
ERIC Educational Resources Information Center
Brodie, Carolyn S.
2004-01-01
This article presents a brief biography of author Jon Scieszka, best known for his first published title, "The True Story of the Three Little Pigs!" which has become a modern classic. The publication of this creative and inventive title led to the numerous fractured fairy tales published since its release in 1989. His books have received numerous…
Author! Author! Making Kids Laugh: Jon Scieszka
ERIC Educational Resources Information Center
Brodie, Carolyn S.
2004-01-01
This article presents a brief biography of author Jon Scieszka, best known for his first published title, "The True Story of the Three Little Pigs!" which has become a modern classic. The publication of this creative and inventive title led to the numerous fractured fairy tales published since its release in 1989. His books have received numerous…
Approximate Expressions for the Period of a Simple Pendulum Using a Taylor Series Expansion
ERIC Educational Resources Information Center
Belendez, Augusto; Arribas, Enrique; Marquez, Andres; Ortuno, Manuel; Gallego, Sergi
2011-01-01
An approximate scheme for obtaining the period of a simple pendulum for large-amplitude oscillations is analysed and discussed. When students express the exact frequency or the period of a simple pendulum as a function of the oscillation amplitude, and they are told to expand this function in a Taylor series, they always do so using the…
An optimized formulation for Deprit-type Lie transformations of Taylor maps for symplectic systems
Shi, Jicong; Yan, Yiton T.
1993-06-01
An optimized iterative formulation is presented for directly transforming a Taylor map of a symplectic system into a Deprit-type Lie transformation, which is a composition of a linear transfer matrix and a single Lie transformation, to an arbitrary order.
Applications of Taylor-Galerkin finite element method to compressible internal flow problems
NASA Technical Reports Server (NTRS)
Sohn, Jeong L.; Kim, Yongmo; Chung, T. J.
1989-01-01
A two-step Taylor-Galerkin finite element method with Lapidus' artificial viscosity scheme is applied to several test cases for internal compressible inviscid flow problems. Investigations for the effect of supersonic/subsonic inlet and outlet boundary conditions on computational results are particularly emphasized.
ERIC Educational Resources Information Center
Martin, Jason
2013-01-01
Taylor series convergence is a complicated mathematical structure which incorporates multiple concepts. Therefore, it can be very difficult for students to initially comprehend. How might students make sense of this structure? How might experts make sense of this structure? To answer these questions, an exploratory study was conducted using…
Forty years later at Taylor Woods: Merging the old and new
John D. Bailey
2008-01-01
The Taylor Woods "Levels-of-Growing-Stock" study was established in 1962 to create a replicated ponderosa pine density experiment for the Southwest, making a valuable addition to research in the Fort Valley Experimental Forest. Basal area treatments ranged from 5-20 m2/ha (19-80 ft2/ac) when installed, designed as...
NASA Astrophysics Data System (ADS)
Mitra, A.; Roychoudhury, R.; Khan, M.
2016-02-01
The stabilization of the Rayleigh-Taylor instability growth rate due to the combined effect of viscosity and compressibility has been studied. A detailed explanation of the observed results has been made from theoretical point of view. The numerical results have been compared qualitatively with those of Plesset and Whipple [Phys. Fluids 17, 1 (1974)] and Bernstein and Book [Phys. Fluids 26, 453 (1983)].
A depositional model for the Taylor coal bed, Martin and Johnson counties, eastern Kentucky
Andrews, W.M.; Hower, J.C.; Ferm, J.C.; Evans, S.D.; Sirek, N.S.; Warrell, M.; Eble, C.F.
1996-01-01
This study investigated the Taylor coal bed in Johnson and Martin counties, eastern Kentucky, using field and petrographic techniques to develop a depositional model of the coal bed. Petrography and chemistry of the coal bed were examined. Multiple benches of the Taylor coal bed were correlated over a 10 km distance. Three sites were studied in detail. The coal at the western and eastern sites were relatively thin and split by thick clastic partings. The coal at the central site was the thickest and unsplit. Two major clastic partings are included in the coal bed. Each represents a separate and distinct fluvial splay. The Taylor is interpreted to have developed on a coastal plain with periodic flooding from nearby, structurally-controlled fluvial systems. Doming is unlikely due to the petrographic and chemical trends, which are inconsistent with modern Indonesian models. The depositional history and structural and stratigraphic setting suggest contemporaneous structural influence on thickness and quality of the Taylor coal bed in this area.
Transition to Taylor vortex flow between combinations of circular and conical cylinders
NASA Astrophysics Data System (ADS)
Lalaoua, Adel
2017-01-01
The stability and flow transitions in the annular gap between two coaxial rotating bodies, termed Taylor-Couette flow, presents a great importance in the field of fluid dynamics. In this paper, the fluid motion in an annulus between cylinder-cone combinations is investigated numerically using CFD simulations for a three dimensional viscous and incompressible flow. The transitional phenomena occurring in this flow are discussed under the effect of opening angles of the outer cylinder. The main goal it is to show how operates the change in the structure of the movement when changing the geometry of the flow through angular deviation, i.e., from coaxial rotating cylinders to an inner cylinder rotating in a conical container. Particular attention is given to the transitional regime and the onset of Taylor vortices when the outer cylinder is replaced with a cone. The numerical calculations are carried out over a range of apex angle α from 0 (classical case) up to 12°. The critical Taylor number, Tac1, characterizing the occurrence of Taylor vortices in the flow, decreases drastically: the first instability mode of transition changes from Tac1 = 41.6, corresponding to the classical case to Tac1 = 20.3 when the apex angle reaches 12°. The velocity distribution and the wavelengths are also presented. It is established that the number of vortices occurring in the gap between rotating cylinder in a cone is inversely proportional to the apex angles.
Ethics, organ donation and tax: a reply to Quigley and Taylor.
Lippert-Rasmussen, Kasper; Petersen, Thomas Søbirk
2012-08-01
A national opt-out system of post-mortem donation of scarce organs is preferable to an opt-in system. Unfortunately, the former system is not always feasible, and so in a recent JME article we canvassed the possibility of offering people a tax break for opting-in as a way of increasing the number of organs available for donation under an opt-in regime. Muireann Quigley and James Stacey Taylor criticize our proposal. Roughly, Quigley argues that our proposal is costly and, hence, is unlikely to be implemented, while Taylor contests our response to a Titmuss-style objection to our scheme. In response to Quigley, we note that our proposal's main attraction lies in gains not reflected in the figures presented by Quigley and that the mere fact that it is costly does not imply that it is unfeasible. In response to Taylor, we offer some textual evidence in support of our interpretation of Taylor and responds to his favoured interpretation of the Titmuss-style objection that many people seem to want to donate to charities even if they can deduct their donations from their income tax. Finally, we show why our views do not commit us to endorsing a free organ-market.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 33 Navigation and Navigable Waters 3 2013-07-01 2013-07-01 false Taylors Bayou, Tex., Beaumont Navigation District Lock; use, administration, and navigation. 207.185 Section 207.185 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE NAVIGATION...
Code of Federal Regulations, 2012 CFR
2012-07-01
... 33 Navigation and Navigable Waters 3 2012-07-01 2012-07-01 false Taylors Bayou, Tex., Beaumont Navigation District Lock; use, administration, and navigation. 207.185 Section 207.185 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE NAVIGATION...
The role of the modified taylor impact test in dynamic material research
NASA Astrophysics Data System (ADS)
Bagusat, Frank; Rohr, Ingmar
2015-09-01
Dynamic material research with strain rates of more than 1000 1/s is experimentally very often done with a Split-Hopkinson Bar, Taylor impact tests or planar plate impact test investigations. At the Ernst-Mach-Institut (EMI), a variant of an inverted classical Taylor impact test is used by application of velocity interferometers of the VISAR type ("Modified Taylor Impact Test", MTT). The conduction of the experiments is similar to that of planar plate impact tests. The data reduction and derivation of dynamic material data can also be restricted to an analysis of the VISAR signal. Due to these properties, nearly each highly dynamic material characterization in our institute done by planar plate investigations is usually accompanied by MTT experiments. The extended possibilities and usefulness of a combined usage of these two highly dynamic characterization methods are explained. Recently, further developed MTT experiments with very small specimen sizes are presented. For the first time, Taylor impact and planar impact specimen can be used for which the load directions even in case of thin plate test material are identical and not perpendicular to each other. Consequences for testing construction elements are discussed.
Taylor Approximations to Logistic IRT Models and Their Use in Adaptive Testing.
ERIC Educational Resources Information Center
Veerkamp, Wim J. J.
2000-01-01
Showed how Taylor approximation can be used to generate a linear approximation to a logistic item characteristic curve and a linear ability estimator. Demonstrated how, for a specific simulation, this could result in the special case of a Robbins-Monro item selection procedure for adaptive testing. (SLD)
Approximate Expressions for the Period of a Simple Pendulum Using a Taylor Series Expansion
ERIC Educational Resources Information Center
Belendez, Augusto; Arribas, Enrique; Marquez, Andres; Ortuno, Manuel; Gallego, Sergi
2011-01-01
An approximate scheme for obtaining the period of a simple pendulum for large-amplitude oscillations is analysed and discussed. When students express the exact frequency or the period of a simple pendulum as a function of the oscillation amplitude, and they are told to expand this function in a Taylor series, they always do so using the…
Validity of the Taylor Hypothesis for Linear Kinetic Waves in the Weakly Collisional Solar Wind
NASA Astrophysics Data System (ADS)
Howes, G. G.; Klein, K. G.; TenBarge, J. M.
2014-07-01
The interpretation of single-point spacecraft measurements of solar wind turbulence is complicated by the fact that the measurements are made in a frame of reference in relative motion with respect to the turbulent plasma. The Taylor hypothesis—that temporal fluctuations measured by a stationary probe in a rapidly flowing fluid are dominated by the advection of spatial structures in the fluid rest frame—is often assumed to simplify the analysis. But measurements of turbulence in upcoming missions, such as Solar Probe Plus, threaten to violate the Taylor hypothesis, either due to slow flow of the plasma with respect to the spacecraft or to the dispersive nature of the plasma fluctuations at small scales. Assuming that the frequency of the turbulent fluctuations is characterized by the frequency of the linear waves supported by the plasma, we evaluate the validity of the Taylor hypothesis for the linear kinetic wave modes in the weakly collisional solar wind. The analysis predicts that a dissipation range of solar wind turbulence supported by whistler waves is likely to violate the Taylor hypothesis, while one supported by kinetic Alfvén waves is not.
Correction of tibial deformity in Paget's disease using the Taylor spatial frame.
Tsaridis, E; Sarikloglou, S; Papasoulis, E; Lykoudis, S; Koutroumpas, I; Avtzakis, V
2008-02-01
A 64-year-old man presented with a severe deformity of the tibia caused by Paget's disease and osteoarthritis of the ipsilateral knee. Total knee replacement required preliminary correction of the tibial deformity. This was successfully achieved by tibial osteotomy followed by distraction osteogenesis using the Taylor spatial frame. The subsequent knee replacement was successful, with no recurrence of deformity.
Treatment of complex foot deformities in children with the taylor spatial frame.
Eidelman, Mark; Katzman, Alexander
2008-10-01
The Taylor spatial frame is a relatively new external fixator able to correct 6-axis deformities with computer accuracy using a virtual hinge. The Taylor spatial frame has gained tremendous popularity, but its use for the correction of foot deformities is still limited. Various ring configurations and a new foot program have recently become available and allow correction of the most difficult foot deformities. This article reports the results of 13 patients (15 frames) with various foot deformities treated at our institution with 3 different Taylor spatial frame configurations (standard rings construction, miter frame, and butt frame). Treatment goals were achieved in 11 patients, while mild residual deformities persisted in 2 patients. Most complications during treatment consisted of pin tract infections. One patient had premature consolidation, which was treated with additional midtarsal osteotomy; 1 had metatarsophalangeal joint subluxation, which was fixed with tendon lengthening and pining of the joint; and 1 had talar subluxation, which was reduced with residual program correction. Based on our experience, we believe the Taylor spatial frame is a very powerful and accurate surgical modality with a relatively short learning curve for the correction for most difficult foot deformities.
Validity of the Taylor hypothesis for linear kinetic waves in the weakly collisional solar wind
Howes, G. G.; Klein, K. G.; TenBarge, J. M.
2014-07-10
The interpretation of single-point spacecraft measurements of solar wind turbulence is complicated by the fact that the measurements are made in a frame of reference in relative motion with respect to the turbulent plasma. The Taylor hypothesis—that temporal fluctuations measured by a stationary probe in a rapidly flowing fluid are dominated by the advection of spatial structures in the fluid rest frame—is often assumed to simplify the analysis. But measurements of turbulence in upcoming missions, such as Solar Probe Plus, threaten to violate the Taylor hypothesis, either due to slow flow of the plasma with respect to the spacecraft or to the dispersive nature of the plasma fluctuations at small scales. Assuming that the frequency of the turbulent fluctuations is characterized by the frequency of the linear waves supported by the plasma, we evaluate the validity of the Taylor hypothesis for the linear kinetic wave modes in the weakly collisional solar wind. The analysis predicts that a dissipation range of solar wind turbulence supported by whistler waves is likely to violate the Taylor hypothesis, while one supported by kinetic Alfvén waves is not.
Taylor Spatial Frame application with the aid of a fine wire half frame.
Whitehouse, Michael R; Livingstone, James A
2008-04-01
The Taylor Spatial Frame has become an important part of the trauma and reconstruction surgeon's armamentarium. We describe a technique to assist in the application of this device that does not hinder the use of the image intensifier or rely on an assistant to hold a constant position and aids provisional fracture reduction.
A New NPGS Special Collection: Norman L. Taylor University of Kentucky Clover Collection
USDA-ARS?s Scientific Manuscript database
Dr. Norman L. Taylor was a world renowned Professor and clover breeder in the Department of Plant and Soil Sciences at the University of Kentucky for 48 years. Following retirement in 2001, he continued working on clovers up until his death in 2010. Dr. Taylor’s entire career was devoted to enhancin...