bluuebunny/crossref_metadata_2025_split huggingface dataset:
The motion of an axisymmetric body falling in a tube at moderate Reynolds numbers
Authors: Brosse Nicolas , Ern Patricia 
Published: January 2013

AbstractThis study concerns the rectilinear and periodic paths of an axisymmetric solid body (short-length cylinder and disk of diameter $d$ and thickness $h$) falling in a vertical tube of diameter $D$. We investigated experimentally the influence of the confinement ratio ($S= d/ D\lt 0. 8$) on the motion of the body, for different aspect ratios ($\chi = d/ h= 3$, $6$ and $10$), Reynolds numbers ($80\lt Re\lt 320$) and a density ratio between the fluid and the body close to unity. For a given body, the Reynolds number based on its mean vertical velocity is observed to decrease when $S$ increases. The critical Reynolds number for the onset of the periodic motion decreases with $S$ in the case of thin bodies ($\chi = 10$), whereas it appears unaffected by $S$ for thicker bodies ($\chi = 3$ and $6$). The characteristics of the periodic motion are also strongly modified by the confinement ratio. A thick body ($\chi = 3$) tends to go back to a rectilinear path when $S$ increases, while a thin body ($\chi = 10$) displays oscillations of growing amplitude with $S$ until it touches the tube (at about $S= 0. 5$). For a given aspect ratio, however, the amplitudes of the oscillations follow a unique curve for all $S$, which depends only on the relative distance of the Reynolds number to the threshold of path instability. In parallel, numerical simulations of the wake of a body held fixed in a uniform confined flow were carried out. The simulations allowed us to determine in this configuration the effect of the confinement ratio on the thresholds for wake instability (loss of axial symmetry at $R{e}_{c 1} $ and loss of stationarity at $R{e}_{c 2} $) and on the maximal velocity ${V}_{w} $ in the recirculating region of the stationary axisymmetric wake. The evolution with $\chi $ and $S$ of ${V}_{w} $ at $R{e}_{c 1} $ was used to define a Reynolds number $R{e}^{\ast} $. Remarkably, for a freely moving body, $R{e}^{\ast} $ remains almost constant when $S$ varies, regardless of the nature of the path.
On the appearance of internal wave attractors due to an initial or parametrically excited disturbance
Authors: Bajars Janis , Frank Jason , Maas Leo R. M. 
Published: January 2013

AbstractIn this paper we solve two initial value problems for two-dimensional internal gravity waves. The waves are contained in a uniformly stratified, square-shaped domain whose sidewalls are tilted with respect to the direction of gravity. We consider several disturbances of the initial stream function field and solve both for its free evolution and for its evolution under parametric excitation. We do this by developing a structure-preserving numerical method for internal gravity waves in a two-dimensional stratified fluid domain. We recall the linearized, inviscid Euler–Boussinesq model, identify its Hamiltonian structure, and derive a staggered finite difference scheme that preserves this structure. For the discretized model, the initial condition can be projected onto normal modes whose dynamics is described by independent harmonic oscillators. This fact is used to explain the persistence of various classes of wave attractors in a freely evolving (i.e. unforced) flow. Under parametric forcing, the discrete dynamics can likewise be decoupled into Mathieu equations. The most unstable resonant modes dominate the solution, forming wave attractors.
On steady and pulsed low-blowing-ratio transverse jets
Authors: Bidan G. , Nikitopoulos D. E. 
Published: January 2013

AbstractThe present experimental and numerical study focuses on the vortical structures encountered in steady and pulsed low-blowing-ratio transverse jets ($0. 150\leq \mathit{BR}\leq 4. 2$), a configuration hardly discussed in the literature. Under unforced conditions at low blowing ratio, a stable leading-edge shear-layer rollup is identified inside the jet pipe. As the blowing ratio is increased, the destabilization and evolution of this structure sheds light on the formation mechanisms of the well-known transverse jet vortical system. A discussion on the nature of the counter-rotating vortex pair in low-blowing-ratio transverse jets is also provided. Under forced conditions, the experimental observations support and extend numerical results of previous fully modulated jet studies. Large-eddy simulation results provide scaling parameters for the classification of starting vortices for partly modulated jets, as well as information on their three-dimensional dynamics. The counter-rotating vortex pair initiation is observed and detailed in both Mie scattering visualizations and simulations. The observations support a mechanism based on stretching of the starting vortical structures because of inviscid induction and partial leapfrogging. Two modes of cross-flow ingestion inside the jet pipe are described as the pulsed jet cycles from high to low values of blowing ratio.
Coupled oscillations of deformable spherical-cap droplets. Part 1. Inviscid motions
Authors: Bostwick J. B. , Steen P. H. 
Published: January 2013

AbstractA spherical drop is constrained by a solid support arranged as a latitudinal belt. This belt support splits the drop into two deformable spherical caps. The edges of the support are given by lower and upper latitudes yielding a ‘spherical belt’ of prescribed extent and position: a two-parameter family of constraints. This is a belt-constrained Rayleigh drop. In this paper we study the linear oscillations of the two coupled spherical-cap surfaces in the inviscid case, and the viscous case is studied in Part 2 (Bostwick & Steen, J. Fluid Mech., vol. 714, 2013, pp. 336–360), restricting to deformations symmetric about the axis of constraint symmetry. The integro-differential boundary-value problem governing the interface deformation is formulated as a functional eigenvalue problem on linear operators and reduced to a truncated set of algebraic equations using a Rayleigh–Ritz procedure on a constrained function space. This formalism allows mode shapes with different contact angles at the edges of the solid support, as observed in experiment, and readily generalizes to accommodate viscous motions (Part 2). Eigenvalues are mapped in the plane of constraints to reveal where near-multiplicities occur. The full problem is then approximated as two coupled harmonic oscillators by introducing a volume-exchange constraint. The approximation yields eigenvalue crossings and allows post-identification of mass and spring constants for the oscillators.
Shallow two-component gravity-driven flows with vertical variation
Authors: Kowalski Julia , McElwaine Jim N. 
Published: January 2013

AbstractGravity-driven geophysical mass flows often consist of a heterogeneous fluid–solid mixture. The complex interplay between the components leads to phenomena such as lateral levee formation in avalanches, or a granular front and an excess fluid pore pressure in debris flows. These effects are very important for predicting runout and the forces on structures, yet they are only partially represented in simplified shallow flow theories, since rearrangement of the mixture composition perpendicular to the main flow direction is neglected. In realistic flows, however, rheological properties and effective basal drag may depend strongly on the relative concentration of the components. We address this problem and present a depth-averaged model for shallow mixtures that explicitly allows for rearrangement in this direction. In particular we consider a fluid–solid mixture that experiences bulk horizontal motion, as well as internal sedimentation and resuspension of the particles, and therefore resembles the case of a debris flow. Starting from general mixture theory we derive bulk balance laws and an evolution equation for the particle concentration. Depth-integration yields a shallow mixture flow model in terms of bulk mass, depth-averaged particle concentration, the particle vertical centre of mass and the depth-averaged velocity. This new equation in this model for the particle vertical centre of mass is derived by taking the first moment, with respect to the vertical coordinate, of the particle mass conservation equation. Our approach does not make the Boussinesq approximation and results in additional terms coupling the momentum flux to the vertical centre of mass. The system is hyperbolic and reduces to the shallow-water equations in the homogeneous limit of a pure fluid or perfect mixing. We highlight the effects of sedimentation on resuspension and finally present a simple friction feedback which qualitatively resembles a large-scale experimental debris flow data set acquired at the Illgraben, Switzerland.
Stability of high-Reynolds-number flow in a collapsible channel
Authors: Pihler-Puzović D. , Pedley T. J. 
Published: January 2013

AbstractWe study high-Reynolds-number flow in a two-dimensional collapsible channel in the asymptotic limit of wall deformations confined to the viscous boundary layer. The system is modelled using interactive boundary-layer equations for a Newtonian incompressible fluid coupled to the freely moving elastic wall under constant tension and external pressure. The deformation of the membrane is assumed to have small amplitude and long wavelength, whereas the flow comprises the inviscid core and the viscous boundary layers on both walls coupled to each other and to the membrane deformation. Firstly, by linking the interactive boundary-layer model to the small-amplitude, long-wavelength inviscid analysis, we conclude that the model is valid only when the pressure perturbations are fixed downstream from the wall indentation, contrary to the common assumption of classical boundary-layer theory. Next we explore possible steady states of the system, showing that a unique steady solution exists when the pressure is fixed precisely at the downstream end of the membrane, but there are multiple states possible if the pressure is specified further downstream. We examine the stability of these states by solving the generalized eigenvalue problem for perturbations to the nonlinear steady solutions and also by performing time integration of the full boundary-layer equations. Surprisingly, we find that no self-excited oscillations develop in the collapsible channel systems with finite-amplitude deformations. Instead, for each point in the parameter space, with the exception of points subject to numerical instabilities associated with the boundary-layer equations, exactly one of the steady states is predicted to be stable. We discuss these findings in relation to the results reported previously in the literature.
The motion of ice stream margins
Authors: Fowler A. C. 
Published: January 2013

AbstractThe recent article by Schoof (J. Fluid Mech., vol. 712, 2012, pp. 552–578) provides a technically demanding solution to the problem of determining ice-stream margin evolution. It is important in opening the way to the future theoretical description of how the ice sheets will melt and sea level will rise as the climate warms. But the sophistication of the mathematics should not operate as a mask to an examination of the credibility of the model.
Magnetic field driven micro-convection in the Hele-Shaw cell
Authors: Ērglis K. , Tatulcenkov A. , Kitenbergs G. , Petrichenko O. , Ergin F. G. , Watz B. B. , Cēbers A. 
Published: January 2013

AbstractMicro-convection caused by ponderomotive forces of the self-magnetic field of a magnetic fluid in the Hele-Shaw cell under the action of a vertical homogeneous magnetic field is studied both experimentally and numerically. It is shown that a non-potential magnetic force at magnetic Rayleigh numbers greater than the critical value causes fingering at the interface between the miscible magnetic and non-magnetic fluids. The threshold value of the magnetic Rayleigh number depends on the smearing of the interface between fluids. Fingering with its subsequent decay due to diffusion of particles significantly increases the mixing at the interface. Velocity and vorticity fields at fingering are determined by particle image velocimetry measurements and qualitatively correspond well to the results of numerical simulations of the micro-convection in the Hele-Shaw cell carried out in the Darcy approximation, which account for ponderomotive forces of the self-magnetic field of the magnetic fluid. Gravity plays an important role at the initial stage of the fingering observed in the experiments.
EFFECT OF LONG-TERM USE OF TILLAGE, RESIDUES AND N LEVELS IN SORGHUM (SORGHUM VULGARE (L)) – CASTOR (RICINUS COMMUNIS) CROPPING SYSTEM UNDER RAINFED CONDITIONS – CROP RESPONSES AND ECONOMIC PERFORMANCE – PART I
Authors: KUSUMA GRACE J. , SHARMA K. L. , SUMACHANDRIKA D. , SRINIVAS K. , MANDAL U. K. , RAJU B. M. K. , KORWAR G. R. , VENKATESWARLU B. , KUMAR SHALANDER , MARUTHI SANKAR G. R. , MUNNALAL  , KUMAR T. SATISH , SAMMI REDDY K. , SHINDE RESHMA 
Published: January 2013

SUMMARYThis experiment was conducted to study the long-term effect of soil management treatments on crop yields, sustainability yield indices (SYI) and soil fertility in rainfed semi-arid tropical Alfisol at Hayathnagar Research Farm, Hyderabad, India, during the period 1995 to 2009. The experiment was conducted in a split–split plot design with conventional tillage (CT) and minimum tillage (MT) as main factors, surface application of sorghum stover @ 2 t ha−1 (SS), fresh Gliricidia loppings @ 2 t ha−1 (GL) and ‘no’ residue (NR) as sub-factors and levels of N viz. 0 (N0), 30 (N30), 60 (N60) and 90 (N90) kg N ha−1 as sub–sub factors in a castor–sorghum two-year rotation. On an average, CT maintained 30.4 and 57.0% higher grain yields of sorghum and castor, respectively, over MT. Between two residues, GL performed well in both the crops. The highest yields of sorghum (1425 kg ha−1) and castor (876 kg ha−1) were recorded at 90 kg N ha−1. CT maintained higher SYI of 0.44 compared to MT (0.38) and higher agronomic efficiency (AE) of 13.5 and 6.76 kg grain kg−1 N for sorghum and castor crop, respectively. Use of crop residue as mulch had an advantage in increasing the yield of both the crops with increase in rainfall under CT even without N application (control), probably by making the soil more receptive to water infiltration, better moisture storage and by reducing the evaporative losses. Using response functions, the optimum fertilizer N requirement was also computed for a given set of tillage and residue combinations. The revised optimum fertilizer N doses for sorghum and castor varied from 45 to 56 kg ha−1 and 46 to 74 kg ha−1, respectively, under different tillage and residue combinations and could be recommended depending upon the soil management practices.
Parasite identification, succession and infection pathways in perch fry (Perca fluviatilis): new insights through a combined morphological and genetic approach
Authors: BEHRMANN-GODEL JASMINCA 
Published: January 2013

SUMMARYIdentification of parasite species is particularly challenging in larval and juvenile hosts, and this hampers the understanding of parasite acquisition in early life. The work described here employs a new combination of methods to identify parasite species and study parasite succession in fry of perch (Perca fluviatilis) from Lake Constance, Germany. Classical morphological diagnostics are combined with sequence comparisons between parasite life-stages collected from various hosts within the same ecosystem. In perch fry at different stages of development, 13 different parasite species were found. Incomplete morphological identifications of cestodes of the order Proteocephalidea, and trematodes of the family Diplostomatidae were complemented with sequences of mitochondrial DNA (cytochrome oxidase 1) and/or nuclear (28 s rDNA) genes. Sequences were compared to published data and used to link the parasites in perch to stages from molluscs, arthropods and more easily identifiable developmental stages from other fishes collected in Lake Constance, which both aided parasite identification and clarified transmission pathways. There were distinct changes in parasite community composition and abundance associated with perch fry age and habitat shifts. Some parasites became more abundant in older fish, whereas the composition of parasite communities was more strongly affected by the ontogenetic shifts from the pelagic to the littoral zone.
Religion and political form: Carl Schmitt's genealogy of politics as critique of Jürgen Habermas's post-secular discourse
Authors: CERELLA ANTONIO 
Published: January 2013

AbstractJürgen Habermas's post-secular account is rapidly attracting attention in many fields as a theoretical framework through which to reconsider the role of religion in contemporary societies. This work seeks to go beyond Habermas's conceptualisation by placing the post-secular discourse within a broader genealogy of the relationships between space, religion, and politics. Drawing on the work of Carl Schmitt, the aim of this article is to contrast the artificial separation between private and public, religious and secular, state and church, and the logic of inclusion/exclusion on which modernity was established. Revisiting this genealogy is also crucial to illustrating, in light of Schmitt's political theory, the problems underlying Habermas's proposal, emphasising its hidden homogenising and universalist logic in an attempt to offer an alternative reflection on the contribution of religious and cultural pluralism within Western democracies.
Postsecular revolution: religion after the end of history
Authors: BARBATO MARIANO 
Published: January 2013

AbstractThis article claims that the revolutions in the Arab world foster insight into more than the spread of liberalism. Fukuyama's end of history has not just reached the Muslim world faster than expected. These revolutions show that strong religion and liberal democracy are compatible: they are postsecular revolutions. As already the revolutions of 1989 proved in some respect, in contrast to the secular ideals of the French Revolution, revolution and religion can go hand in hand in a postsecular way. Praying and making revolution does not need to end in a religious autocracy as 1979 in Iran. Religious citizens stood up praying for democracy and the rule of law against secular regimes which legitimised themselves as a bulwark against sinister forces of religion. Analysing the revolutions of 1989, Jürgen Habermas speaks of ‘catching-up revolutions’ which brought nothing new to the course of history. Yet after 9/11 he started to develop his idea of a postsecular society in which secular and religious citizens are equally entitled to make their arguments in a public sphere. Criticising the early Habermas with the later, the article argues that the postsecular revolutions of 1989 and 2011 are preparing the ground for a postsecular democracy.
Civilisation, dialogue, security: the challenge of post-secularism and the limits of civilisational dialogue
Authors: BILGIN PINAR 
Published: January 2013

AbstractThe purposes of this article are twofold: (1) to consider the extent to which Dialogue of Civilisations (DoC) initiatives, as alternative visions of post-secular world order, are likely to address insecurities that they identify; and (2) to point to other insecurities that are likely to remain unidentified and unaddressed in the process. In their present conception, DoC initiatives risk falling short of addressing the very insecurities they prioritise (the stability of inter-state order) let alone attending to those experienced by non-state referents, which they overlook. The article advances three points in three steps. First, I point to how projects of civilisational dialogue have bracketed civilisation, thereby leaving intact the Huntingtonian notion of civilisations as religiously unified autochthonous entities. Second, I argue that while contributing to opening up space for communication, DoC initiatives have nevertheless failed to employ a dialogical approach to dialogue between civilisations. Third, I tease out the notion of security underpinning DoC initiatives and argue that the proponents DoC, in their haste to avert a clash, have defined security narrowly as the absence of war between states belonging to different civilisations. Theirs is also a shallow notion of security insofar as it fails to capture the derivative character of security and insecurity.
Outbreak investigation and case-control study: penta-resistant Salmonella Typhimurium DT104 associated with biltong in London in 2008
Authors: MINDLIN M. J. , LANG N. , MAGUIRE H. , WALSH B. , VERLANDER N. Q. , LANE C. , TAYLOR C. , BISHOP L. A. , CROOK P. D. 
Published: January 2013

SUMMARYIn August 2008 an outbreak of Salmonella Typhimurium DT104 occurred in South West London. Sixteen cases were identified with a particular multilocus variable number tandem repeat analysis (MLVA) pattern. In a matched case-control study 14 primary cases were included. These were defined as individuals with gastrointestinal symptoms and Salmonella Typhimurium DT104 isolated from a stool specimen, with a characteristic antibiotic resistance profile and MLVA pattern, and diagnosed in a local laboratory. Four controls per case were matched on age, gender and area of residence. Cases were 26 times more likely than controls to have eaten beef biltong, a South African speciality meat product (odds ratio 25·83, 95% confidence interval 4·92–135·59, P < 0·01). Although environmental investigation failed to identify Salmonella in the food product we conclude that beef biltong consumption led to this outbreak. This conclusion has importance in informing the ongoing risk assessment relating to uncontrolled foodstuffs.
Sampling methane in basalt on Earth and Mars
Authors: McMahon Sean , Parnell John , Blamey Nigel J.F. 
Published: January 2013

AbstractIf confirmed, the extremely low concentrations of methane (CH4) detected in the Martian atmosphere may represent reservoirs and emission processes that would normally be considered negligible on Earth. One such process is the release of ancient volatiles from fluid inclusions and interstitial sites in rocks and minerals during erosion or geothermal activity. Using a highly sensitive rock-crushing and mass-spectrometry technique previously shown to detect CH4 in serpentinites and hydrothermal mineral deposits, we have demonstrated that CH4 and other ancient volatiles can be recovered from basalt, the dominant rock type on the Martian surface. Basalt samples from a wide range of ages and geological systems were tested, all of which released CH4 when crushed. Oxidative weathering was associated with lower quantities of CH4. Otherwise, CH4 recoverability showed no relationship with age or geological context. Mineral veins, cross-cutting one locality were found to share the volatile composition of the basalt. In general, the results suggest that CH4-release from ancient basalts could be a significant process on Mars, which could be further investigated by Martian rovers using a similar rock-crushing and mass spectrometry technique in situ.
On The Identity of Weelkes’ ‘Fogo’
Authors: Milne J. G. C. 
Published: January 2013

Recently I found myself again singing Weelkes' “Thule, the period of cosmography” from the Madrigals of Six Parts published in 1600 and, not for the first time, wondered where Fogo is:-“The Andalusian merchant, that returnsLaden with cochineal and China dishes,Reports in Spain how strangely Fogo burnsAmidst an ocean full of flying fishes.”The first part of the madrigal refers to Hekla and Etna, both well-known volcanoes of the present day, but the location of Fogo is much less certain. E.H. Fellowes stated that it was a volcano in Tierra del Fuego but gave no evidence to support such an identification. It seems that everyone nowadays merely repeats Fellowes’ opinion, and it is quoted unchanged in the latest edition of English Madrigal Verse.