bluuebunny/crossref_metadata_2025_split huggingface dataset:
Revisionism and the Irish Reformation
Authors: BOTTIGHEIMER KARL 
Published: July 2002

The Irish Reformation remains a troubled subject, and not from
lack of recent scholarly attention. It has attracted an abundance
of high-quality work, but its vexed nature as a topic is illuminated
by a long, authoritative essay published in 1998 by Brendan Bradshaw,
one of the foremost students of early-modern Irish history. The essay is
entitled ‘The English Reformation and identity formation in Ireland and
Wales’, as befits the volume in which it appeared: British consciousness and
identity: the making of Britain, 1533–1707. But the pageheads of the sixty-nine-page article call it ‘The Reformation in Ireland’, and this is a much
more accurate description of its contents, as even its author might agree.Whether denominated ‘The Irish Reformation’ or ‘The Reformation
in Ireland’, the event lacks the familiarity of historical chestnuts like the
Congress of Vienna or The Thirty-Years War, well-worn, frequently-taught subjects (at least in the old canon of European history) about
which there was a modicum of consensus, sufficient at least to allow them
to be discussed. But in order for events to be debated, there needs to be
agreement that they happened, and in that respect the Irish Reformation
is something of a non-starter.
Saltation and incipient suspension above a flat particle bed below a turbulent boundary layer
Authors: NISHIMURA K. , HUNT J. C. R. 
Published: July 2002

Experiments were conducted in a wind tunnel in which a turbulent boundary layer
was naturally grown over flat beds of three types of nearly mono-disperse spherical
particles with different diameters, densities and coefficient of restitution (r) (snow,
0.48 mm, 910 kg m−3; mustard seeds, 1.82 mm, 1670 kg m−3,
r = 0.7; ice particles, 2.80 mm, 910 kg m−3, r = 0.8–0.9).
The surface wind speeds (defined by the friction
velocity u∗) were varied between 1.0 and 1.9 times the threshold surface wind speed
(defined by u∗t). The trajectories, and ejection and impact velocities of the particles
were recorded and analysed, even those that were raised only about one diameter into the flow.Measurements of the average horizontal flux of saltating particles per unit area, f(z),
at each level z above the surface showed that, for
u∗/u∗t [les ] 1.5, f(z) is approximately
independent of the particle density and decreases exponentially over a vertical scale
length lf, that is about 3 to 4 times the estimated mean height of the particle
trajectories 〈h〉. Numerical simulations of saltating grains were computed using the
measured probabilities of ejection velocities and the mean velocity profile of the air
flow, but neglecting the direct effect of the turbulence. The calculated mean values
of the impact velocities and the trajectory dimensions were found to agree with the
measurements in the saltation range, where
u∗/u∗t < 1.5. Similarly, in this range
the simulations of the horizontal flux profile and integral are also consistent with the
measurements and with Bagnold's u∗3 formula, respectively.When u∗/u∗t [ges ] 1.5, and
u∗/VT [ges ] 1/10, where VT
is the settling velocity, a transition
from saltation to suspension occurs. This is indicated by the change in the mean mass
flux profile which effectively becomes uniform with height (z) up to the top of
the boundary layer. An explanation is provided for this low value of turbulence
at transition relative to the settling velocity in terms of the random motion of
the particles under the action of the turbulence when they reach the tops of their
parabolic trajectories. The experiments show that, as u∗/u∗t
increases from 1.0 to 1.9 the normalized mean vertical impact velocity
〈V3I〉/u∗ decreases by nearly 60% to
about 0.6, which is less than 50% of the value for fluid particles. There is also a
decrease in the vertical and horizontal component of the ejection velocity to values
of 0.8 and 2.3, which are much less than their values in the saltation regime. We
hypothesize that at the transition from saltation to suspension the ejection process
changes quite sharply from being determined by impact collisions to being the result
of aerodynamic lift forces and upward eddy motions.
Transient response of a compressible fluid in a rapidly rotating circular pipe
Authors: PARK JUN SANG , HYUN JAE MIN 
Published: July 2002

The transient adjustment process of a compressible fluid in a rapidly rotating pipe is
studied. The system Ekman number E is small, and the assumptions of small Mach
number and the heavy-gas limit (γ = 1.0) are invoked. Fluid motion is generated
by imposing a step-change perturbation in the temperature at the pipe wall Tw.
Comprehensive analytical solutions are obtained by deploying the matched asymptotic
technique with proper timescales O(E−1/2) and
O(E−1). These analytical solutions are
shown to be consistent with corresponding full numerical solutions. The detailed
profiles of major variables are delineated, and evolution of velocity and temperature
fields is portrayed. At moderate times, the entire flow field can be divided into two
regions. In the inner inviscid region, thermo-acoustic compression takes place, and
the process is isothermal–isentropic with the angular momentum being conserved.
In the outer viscous region, diffusion of angular momentum occurs. The principal
dynamic mechanisms are discussed, and physical rationalizations are offered. The
essential differences between the responses of a compressible and an incompressible
fluid are highlighted.The issue of stability of the analytically obtained flow is addressed by undertaking
a formal stability analysis. It is illustrated that, within the range of parameters of
present concern, the flow is stable when ε ∼ O(E).
The anatomy of the mixing transition in homogeneous and stratified free shear layers
Authors: CAULFIELD C. P. , PELTIER W. R. 
Published: July 2002

We investigate the detailed nature of the ‘mixing transition’ through which turbulence
may develop in both homogeneous and stratified free shear layers. Our focus is
upon the fundamental role in transition, and in particular the associated ‘mixing’
(i.e. small-scale motions which lead to an irreversible increase in the total potential
energy of the flow) that is played by streamwise vortex streaks, which develop once
the primary and typically two-dimensional Kelvin–Helmholtz (KH) billow saturates
at finite amplitude.Saturated KH billows are susceptible to a family of three-dimensional secondary
instabilities. In homogeneous fluid, secondary stability analyses predict that the stream-wise vortex streaks originate through a ‘hyperbolic’ instability that is localized in the
vorticity braids that develop between billow cores. In sufficiently strongly stratified
fluid, the secondary instability mechanism is fundamentally different, and is associated
with convective destabilization of the statically unstable sublayers that are created as
the KH billows roll up.We test the validity of these theoretical predictions by performing a sequence of
three-dimensional direct numerical simulations of shear layer evolution, with the
flow Reynolds number (defined on the basis of shear layer half-depth and half
the velocity difference) Re = 750, the Prandtl number of the fluid Pr = 1, and
the minimum gradient Richardson number Ri(0) varying between 0 and 0.1. These
simulations quantitatively verify the predictions of our stability analysis, both as to
the spanwise wavelength and the spatial localization of the streamwise vortex streaks.
We track the nonlinear amplification of these secondary coherent structures, and
investigate the nature of the process which actually triggers mixing. Both in stratified
and unstratified shear layers, the subsequent nonlinear amplification of the initially
localized streamwise vortex streaks is driven by the vertical shear in the evolving
mean flow. The two-dimensional flow associated with the primary KH billow plays
an essentially catalytic role. Vortex stretching causes the streamwise vortices to extend
beyond their initially localized regions, and leads eventually to a streamwise-aligned
collision between the streamwise vortices that are initially associated with adjacent
cores.It is through this collision of neighbouring streamwise vortex streaks that a final
and violent finite-amplitude subcritical transition occurs in both stratified and
unstratified shear layers, which drives the mixing process. In a stratified flow with
appropriate initial characteristics, the irreversible small-scale mixing of the density
which is triggered by this transition leads to the development of a third layer within
the flow of relatively well-mixed fluid that is of an intermediate density, bounded by
narrow regions of strong density gradient.
Downstream and upstream influence in river meandering. Part 2. Planimetric development
Authors: SEMINARA G. , ZOLEZZI G. , TUBINO M. , ZARDI D. 
Published: July 2002

The exact solution of the problem of river morphodynamics derived in Part 1 is
employed to formulate and solve the problem of planimetric evolution of river
meanders. A nonlinear integrodifferential evolution equation in intrinsic coordinates
is derived. An exact periodic solution of such an equation is then obtained in terms
of a modified Fourier series expansion such that the wavenumbers of the various
Fourier modes are time dependent. The amplitudes of the Fourier modes and their
wavenumbers satisfy a nonlinear system of coupled ordinary differential equations
of the Landau type. Solutions of this system display the occurrence of two possible
scenarios. In the sub-resonant regime, i.e. when the aspect ratio of the channel is
smaller than the resonant value, meandering evolves according to the classical picture:
a periodic train of small-amplitude sine-generated meanders migrating downstream
evolve into the classical, upstream skewed, train of meanders of Kinoshita type.
Evolution displays all the experimentally observed features: the meander growth rate
increases up to a maximum and then decreases, while the migration speed decreases
monotonically. No equilibrium solutions are found. In the super-resonant regime the
picture is essentially reversed: downstream skewing develops while meanders migrate
upstream.Numerical solutions of the planimetric evolution equation are obtained for the
case when the initial channel pattern exhibits random small perturbations of the
straight configuration. Under these conditions, the evolution displays the typical
features of solutions of the Ginzburg–Landau equation, in particular, the occurrence
of spatial modulations of the meandering pattern which organizes itself in the form of
wavegroups. Furthermore, multiple loops develop in the advanced stage of meander
growth.
The horizontal scale of rotating convection in the

geostrophic regime
Authors: SAKAI SATOSHI 
Published: July 2002

The horizontal scale of rotating convection with rigid boundary

conditions is studied.

The range of Rayleigh number concerned is moderate, i.e. large enough

to induce a finite-amplitude convection but small enough so that the

geostrophic processes are significant.On considering an experimental law of the Nusselt number and some

constraints of elemental geostrophic processes, the horizontal scale

of the convection can be estimated. This estimation strongly depends

on the ratio between the thicknesses of the Ekman layer and the

thermal boundary layer, and does not depend monotonically on the

Rayleigh number. This dependency is compatible with the experimental

results of Rossby (1969).The estimated horizontal scale was checked by laboratory experiments.

The horizontal temperature distribution was visualized by thermal

liquid-crystal capsules dispersed in the working fluid. The horizontal

scale was measured by counting vortices. The experimental results

agree fairly well with the estimated scale.
Strongly turbulent Rayleigh–Bénard

convection in mercury: comparison with results

at moderate Prandtl number
Authors: CIONI S. , CILIBERTO S. , SOMMERIA J. 
Published: July 2002

An experimental study of Rayleigh–Bénard convection
in

the strongly turbulent

regime is presented. We report results obtained at low Prandtl number (in
mercury,

Pr = 0.025), covering a range of Rayleigh numbers

5 × 106 < Ra < 5 × 109, and

compare them with results at Pr∼1.

The convective chamber consists of a cylindrical cell of aspect ratio 1.Heat flux measurements indicate a regime with Nusselt number increasing
as

Ra0.26, close to the 2/7 power observed at

Pr∼1, but with a smaller prefactor, which

contradicts recent theoretical predictions. A transition to a new turbulent

regime is suggested for Ra ≃ 2 × 109,

with significant increase of the Nusselt number. The

formation of a large convective cell in the bulk is revealed by its thermal

signature on the bottom and top plates. One frequency of the temperature

oscillation is related

to the velocity of this convective cell. We then obtain the typical temperature
and

velocity in the bulk versus the Rayleigh number, and compare them with
similar

results known for Pr∼1.We review two recent theoretical models, namely the mixing zone model
of Castaing

et al. (1989), and a model of the turbulent boundary layer by

Shraiman & Siggia

(1990). We discuss how these models fail at low Prandtl number, and propose

modifications for this case. Specific scaling laws for fluids at low Prandtl

number are then obtained, providing an interpretation of our experimental

results in mercury, as well as extrapolations for other liquid metals.
Three-dimensional effects in turbulent bluff-body wakes
Authors: PRASAD ANIL , WILLIAMSON CHARLES H. K. 
Published: July 2002

There has recently been a surge in activity concerning the

development of three-dimensionality in the wakes of nominally two-dimensional

bluff bodies, yielding the

realization that end effects can influence the

wake vortex shedding pattern over long

spanlengths. Much of this work has been focused on low Reynolds

numbers (Re),

but virtually no studies have investigated to what extent it is possible
to control

shedding patterns at higher Reynolds numbers, through the use of end manipulation.

In the present paper, we demonstrate that it is possible to induce parallel
shedding,

oblique shedding and vortex dislocations, by manipulation of the end conditions,
over

a large range of Reynolds number. Such patterns affect the frequency of
primary

wake instability and its amplitude of fluctuation, as they do at low Reynolds
number,

although distinct differences are found at the higher Reynolds numbers.We find that imposition of oblique shedding conditions at high Reynolds
number

leads to a spatial variation of both the oblique shedding

angle and shedding frequency

across the span, and to sparse dislocations which are not

restricted to the spanwise end

regions, as they are at low Reynolds numbers (under similar geometrical
conditions).

In the wake transition regime (Re=190–250), it is

confirmed that the spontaneous

appearance of vortex dislocations in mode-A shedding precludes the control
of

shedding patterns using end manipulation. However, it has proven possible
to extend

the regime of Reynolds number where dislocations ‘naturally’

exist to Re>250,

by introducing them artificially through end control, where they would
otherwise

not occur. The possibility of introducing dislocations and of inducing
oblique vortex

shedding at higher Reynolds numbers has practical significance,

if one can deliberately

decorrelate the vortex shedding, and hence reduce the spanwise-integrated
unsteady

fluid forces on the body.We confirm the existence of a transition in the mode of shedding at

Re≈5000

(originally found by Norberg 1987) under conditions where parallel shedding
is

attempted. This mode transition displays similarities to an inverse

of the mode A→mode B transition that is found in the

wake transition regime. It is clear that vortex

dislocations occur beyond Re=5000, although it is

not clear why the flow is unstable

to such a mode. Furthermore, there appears to be some support for the suggestion

that vortex dislocations may be a feature of the flow for Re

at least up to 30×103,

as evidenced by the work of Norberg (1994).
The anomalous wake accompanying bubbles

rising in a thin gap: a mechanically forced Marangoni flow
Authors: BUSH JOHN W. M. 
Published: July 2002

A novel wake structure, observed as penny-shaped air bubbles rise
at moderate

Reynolds number through a thin layer of water bound between parallel glass
plates

inclined at a shallow angle relative to the horizontal, is reported. The
structure of

the wake is revealed through tracking particles suspended in the water.
The wake

completely encircles the rising bubble, and is characterized by a reverse

surface flow or ‘edge jet’ which transports fluid in a thin
boundary

layer along the bubble surface from

the tail to the nose at speeds which are typically an order of magnitude

larger than the

bubble rise speed. A consistent physical explanation for the wake structure

is proposed.

The wake is revealed to be a manifestation of the three-dimensionality
of the flow

in the suspending fluid. The bubble surface advances through a rolling
motion, thus

generating regions of surface divergence and convergence at, respectively,

the leading and trailing edges of the bubble. A nose-to-tail gradient in
surfactant

concentration is

thus established, and the associated surface tension gradient drives the
edge

jet. The dependence of the wake structure on the suspending fluid is

examined experimentally.Surfactants play an anomalous role in the reported flow, serving to
promote rather

than suppress surface motions. The wake structure is an example of a mechanically

forced Marangoni flow, and so represents a mechanical analogue of that

accompanying thermocapillary drop motion in microgravity. A theoretical
model

is developed

which reproduces the salient features of the flow, and on the basis of
which an

estimate is made of the mechanically induced surface tension gradient

along the bubble surface.
Strongly nonlinear convection cells in a rapidly
rotating fluid layer: the tilted f-plane
Authors: JULIEN KEITH , KNOBLOCH EDGAR 
Published: July 2002

Investigation of the linear stability problem for rapidly rotating
convection on an
f-plane has revealed the existence of two distinct scales in the
vertical structure of
the critical eigenfunctions: a small length scale whose vertical wavenumber

kz is
comparable with the large horizontal wavenumber k⊥ selected at onset,
and a
large-scale modulation which forms an envelope on the order of the layer
depth d. The
small-scale structure in the vertical results from a geostrophic balance
imposed by the
Taylor–Proudman constraint. This primary balance forces rotational
alignment and
confines fluid motions to planes perpendicular to the rotation axis. For
convective
transport in the vertical this constraint must be relaxed. This is achieved
by molecular
dissipation which allows weak upward (downward) spiralling of hot (cold)
fluid
elements across the Taylor–Proudman planes and results in a large-scale
vertical
modulation of the Taylor columns.In the limit of fast rotation (i.e. large Taylor number) a multiple-scales
analysis leads
to the determination of a critical Rayleigh number as a function of wavenumber,
roll
orientation and the tilt angle of the f-plane. The corresponding

critical eigenfunction
represents the core solution; matching to passive Ekman boundary layers
is required
for a complete solution satisfying boundary conditions.An extension of this analysis, introduced by Bassom & Zhang (1994),
is used to
describe strongly nonlinear two-dimensional convection, characterized by
significant
departures of the mean thermal field from its conduction profile. The analysis
requires
the solution of a nonlinear eigenvalue problem for the Nusselt number (for
steady
convection) and the Nusselt number and oscillation frequency (for the overstable

problem). The solutions of this problem are used to calculate horizontal
and vertical
heat fluxes, as well as Reynolds stresses, as functions of both the latitude
and roll
orientation in the horizontal, and these are used to calculate self-consistently

north–south and east–west mean flows. These analytical predictions

are in good agreement with the results of three-dimensional simulations
reported
by Hathaway & Somerville (1983).
Lagrangian accelerations in geostrophic turbulence
Authors: HUA BACH LIEN , McWILLIAMS JAMES C. , KLEIN PATRICE 
Published: July 2002

A distinctive property of Lagrangian accelerations in geostrophic
turbulence is that
they are governed by the large and intermediate scales of the flow, both
in time
and space, so that the inertial part of the dynamics plays a much larger
role than
in three-dimensional turbulence where viscous effects are stronger. For
the case
of geostrophic turbulence on a β-plane, three terms contribute to
the Lagrangian
accelerations: the ageostrophic pressure gradient which often is the largest
term, a
meridional acceleration due to the β-effect, and an acceleration due
to horizontally
divergent ageostrophic motions. Both their spectral characteristics and
patterns in
physical space are studied in this paper. In particular the total accelerations
field has
an inertial spectrum slope which is identical to the geostrophic velocity
field inertial
slope.The accelerations gradient tensor is shown to govern the topology of
quasi-geostrophic
stirring and transport properties. Its positive eigenvalues locate accurately

the position of extrema of potential vorticity gradients. The three-dimensional

distribution of tracer gradients is such that the vertical distribution
is entirely constrained
by the horizontal one, while the reverse is not true. We make explicit
analytically
their dependence on the three-dimensional accelerations gradient.
Examination of the flow near the
leading edge of attached cavitation.
Part 1. Detachment of two-dimensional
and axisymmetric cavities
Authors: LEGER A. TASSIN , CECCIO S. L. 
Published: July 2002

The flow near the cavity detachment region of stable attached cavitation
was
examined using qualitative and quantitative flow visualization. The non-cavitating
and
cavitating flows around a hydrophilic brass and hydrophobic Teflon sphere
and cylinder
were examined. The location of non-cavitating boundary layer separation
and
cavity detachment was related to the free-stream Reynolds and cavitation
numbers.
The shape of the cavity near the detachment was greatly affected by the
material
of the cavitating object. The cavity interface on the hydrophilic test
objects curved
downstream to form a forward facing step. A region of recirculating fluid
existed
upstream of the cavity interface. The cavity detachment on the hydrophobic
test
objects was much closer to the location of boundary layer separation. The
forward
facing step and the recirculating region were nearly absent.The measured flow field near the surface of the brass sphere, cylinder,
and hydrofoils
under cavitating and non-cavitating conditions was used to calculate the
position
of two-dimensional laminar boundary layer separation.
Thwaites' and Stratford's
methods were used to predict the location of boundary layer separation
upstream of
the cavity detachment. The predictions compared well with the observed
position of
separation.