bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of late season insect infestation on yield, yield
components and oil quality of Brassica napus, B. rapa,
B. juncea and Sinapis alba in the Pacific Northwest
region of the United States
Authors: BROWN J. , McCAFFREY J. P. , HARMON B. L. , DAVIS J. B. , BROWN A. P. , ERICKSON D. A.
Published: July 2002

The effect of late season insect infestation on seed yield, yield components, oil content and oil quality
of two canola species (Brassica napus L. and B. rapa L.) and two mustard species (B. juncea L. and
Sinapis alba L.) was examined over 2 years. In each year, ten genotypes from each species were
evaluated with late season insects controlled with either methyl parathion or endosulfan insecticides,
and without insecticides. Major late season insect damage in 1992 was caused by cabbage seedpod
weevil (Ceutorhynchus assimilis Paykull), while diamondback moth (Plutella xylostella L.) and aphids
(primarily cabbage aphids, Brevicoryne brassicae L.) were major insect pests in 1993. Insecticide
application was very effective in controlling diamondback moth larvae and adult cabbage seedpod
weevils, but only partially effective in controlling aphids. Higher numbers of diamondback moth
larvae were observed on mustard species compared to canola species. S. alba was completely resistant
to cabbage seedpod weevil and there was no damage due to this pest observed. Aphid colonization
was observed on plants from all species, but infestation on S. alba and B. rapa occurred too late to
have a major effect on seed yield. Seed oil content of canola species was significantly reduced by insect
damage although oil quality (indicated by fatty acid profile) was not affected by insect attack.
Uncontrolled insect infestation reduced seed yield of canola species by 37 and 32% in B. napus and
B. rapa, respectively. Least yield reduction occurred in S. alba, where average yield reduction from
plants in untreated control plots was <10% of insecticide treated plants. S. alba, therefore, has good
potential as an alternative crop suitable for northern Idaho because it can be grown with reduced late
season insecticide application.
Effects of irrigation water salinity and leaching fraction on the growth of six halophyte species
Authors: NOAMAN MAHER N. , EL-HADDAD EL-SAYED
Published: July 2002

A pot experiment was carried out at Nahshala Farm, about 50 km from Al-Ain, UAE, during the
1998/99 growing seasons, using six halophytes: Spartina sp., Distichlis palmeri, Paspalum vaginatum,
Juncus roemerianus, Salicornia bigelovii and Batis maritima, under two levels of leaching fraction, 0·25
and 0·50 and three levels of irrigation salinity, 10, 20 and 40 g/l. The objectives of the experiment were
twofold: (1) to find out the optimum and threshold of saline water irrigation to keep salinity level
down as much as possible in the soil using the leaching fraction technique; and (2) to study the
response (growth and biomass production) of some halophytes to different levels of salinity. The
experiment was conducted in triplicate with a split-plot design arranged in a randomized complete
block. Results indicate that these halophyte species can be grown productively at a leaching fraction
between 0·25 and 0·50 when salinity of the irrigation water is less than 20 g/l. At higher salinities,
Salicornia bigelovii can grow and yield satisfactorily under these conditions, while the other species
may require more frequent irrigation at higher leaching fractions. Some of these tested halophytes
may be able to revegetate the salt-affected lands and be a potential source of forage in these harsh
habitats. This study supports the idea of seawater agriculture by demonstrating the possibility of
using some high salt-tolerant halophytes at relatively higher leaching fraction in order to maintain
satisfactory yield production of such halophytes.
COLOSTRUM FEEDING BEHAVIOUR AND INITIATION OF BREAST-FEEDING IN RURAL BANGLADESH
Authors: HOLMAN DARRYL J. , GRIMES MICHAEL A.
Published: July 2002

Human breast milk is primarily colostrum immediately following birth. Colostrum gradually changes to mature milk over the next several days. The role of colostrum in fighting infections and promoting growth and development of the newborn is widely acknowledged. This role is mediated by differences across cultures in the acceptability of colostrum and the prevalence of colostrum feeding. This study examined the prevalence of colostrum feeding and time to initiation of breast-feeding in 143 rural Bangladeshi women in Matlab thana. Structured interviews were collected during a 9-month prospective study conducted in 1993. Women were usually interviewed within 4 days of giving birth and were asked about whether or not they fed their child colostrum and the number of hours until they began breast-feeding the baby. Ninety per cent of the mothers reported feeding their newborn colostrum. A logistic regression found no effect on the prevalence of colostrum feeding from the following covariates: mother's age, parity, history of pregnancy loss, child's sex, mother's self-report of delivery complications, and the time from birth to interview. Fifty-nine per cent of mothers initiated breast-feeding within 4 h, and 88% within 12 h of parturition. Survival analysis was used to estimate the effects of covariates on the time from delivery to initial breast-feeding. Time to initial breast-feeding was delayed slightly, but significantly, for older mothers, for male infants, and by mothers who did not report delivery complications. The percentage of mothers who fed their child colostrum was higher, and times to initial breast-feeding were shorter, than almost all previous reports from South Asia. These findings might be explained, in part, by methodological differences among studies, but it is suggested that recent changes towards earlier initiation of breast-feeding have taken place in rural Bangladesh.
THE CONSISTENCY AND VALIDITY OF REPRODUCTIVE ATTITUDES: EVIDENCE FROM MOROCCO
Authors: BANKOLE AKINRINOLA , WESTOFF CHARLES F.
Published: July 2002

Information on reproductive attitudes is now routinely collected in fertility surveys in developing countries, and has become very important for understanding fertility behaviour. The quality of this information, however, is rarely assessed, partly due to lack of necessary data. In this paper, the recently completed panel survey in Morocco by the Demographic and Health Surveys (DHS) was used to investigate the consistency of reporting of ideal number of children, reproductive intentions and the planning status of the last birth. The validity of reproductive intentions for subsequent fertility behaviour was also examined. The findings indicate that the three measures of reproductive attitudes are subject to different degrees of measurement error. The measure of reproductive intentions is the most consistent of the three, followed by ideal number of children. The latter is much more consistent at the aggregate level than at the individual level. The reliability of the planning status of the last birth is marred, mainly by an unwanted child being reclassified as 'wanted' with time since the birth of the child. The reproductive intentions of women were also found to be positively related to their subsequent fertility.
THE RELATION OF BIRTH ORDER TO SEXUAL ORIENTATION IN MEN AND WOMEN
Authors: BLANCHARD RAY , ZUCKER KENNETH J. , SIEGELMAN MARVIN , DICKEY ROBERT , KLASSEN PHILIP
Published: July 2002

Homosexual men have a higher mean birth order than do heterosexual men, primarily because they have a greater number of older brothers. The purpose of this study was to determine whether the same difference occurs in homosexual vs heterosexual women. The probands were 964 homosexual and heterosexual, male and female volunteers, from whom birth order data were collected with self-administered questionnaires. The homosexual men had more older brothers than the heterosexual men, but they did not have more older sisters, younger brothers, or younger sisters. The homosexual women did not differ from the heterosexual women with regard to any class of sibling. These results are consistent with the hypothesis that the high birth order of homosexual men reflects the progressive immunization of certain mothers to H-Y antigen by succeeding male fetuses, and the increasing effects of H-Y antibodies on sexual differentiation of the brain in succeeding male fetuses.
Method of quantifying the loss of acidification activity of lactic acid
starters during freezing and frozen storage
Authors: FONSECA FERNANDA , BÉAL CATHERINE , CORRIEU GEORGES
Published: July 2002

We have developed a method to quantify the resistance to freezing and
frozen storage of lactic acid starters, based on measuring the time necessary to reach
the maximum acidification rate in milk (tm) using the Cinac system. Depending on
the operating conditions, tm increased during the freezing step and storage. The loss
of acidification activity during freezing was quantified by the difference (Δtm)
between the tm values of the concentrated cell suspension before and after freezing.
During storage at −20 °C, linear relationships between tm and the storage time were
established. Their slope, k, allowed the quantitation of the decrease in acidification
activity during 9–14 weeks of frozen storage. The method was applied to determine
the resistance to freezing and frozen storage of four strains of lactic acid bacteria
and to quantify the cryoprotective effect of glycerol.
The Second Generation of the 'Sambin Revolution': New Writings on the Humiliati
Authors: ANDREWS FRANCES
Published: July 2002

Until recently, the Humiliati of northern Italy have
not been fortunate in their historiography. If they are
known to Anglophone medievalists, it is usually in walk-on
parts, either as the heretics condemned in the bull
Ad abolendam at the Council of Verona in
1184, or as the pious enthusiasts, precursors of the
mendicants, who were
recognised and approved by Innocent III in 1201.
Although they went on
to play a prominent role in many north Italian regions,
the later history
of the Humiliati has frequently been treated with
indifference, except
perhaps by those interested in the development of the
north Italian wool
industry. This is partly because, unlike their contemporaries
the Waldensians, the Humiliati did not have to keep defending
themselves: their orthodoxy was not long questioned and they
became part of the backbone of the religious communities of
north Italian cities, taken for
granted and largely untrumpeted. Their lack of
‘history’ also reflects the
failure of the order to survive the Counter-Reformation.
When one of the brethren, objecting strongly to attempts
by Carlo Borromeo to reform
their much decayed houses, tried quite literally to
shoot the messenger,
the male order was abruptly disbanded and most of the
sources for their
communities were dispersed. They thus lack either the
later brethren interested in the origins of their own
congregation who have so often
driven the history industry of other religious orders,
or a convenient body
of sources on which to base such work.
The Parochial Roots of Laudianism
Revisited: Catholics, Anti-Calvinists
and ‘Parish Anglicans’ in Early
Stuart England
Authors: WALSHAM ALEXANDRA
Published: July 2002

There is no end in sight to historical squabbles about the speed,

impact and enduring cultural and ecclesiastical legacies of the
English Reformation. The past two decades have witnessed a
lively and stimulating debate about the reception and entrenchment of
Protestant belief and practice in local contexts. Over the same period
we
have seen a series of heated and animated exchanges about the
developments taking place within the early Stuart Church and the role
they played in triggering the outbreak of hostilities between Charles I
and
Parliament in 1642. While the focus of the first controversy has been the

relationship between zealous Protestantism and the vast mass of the
ordinary people, the second has been conducted almost exclusively at the

level of the learned polemical literature of the clerical elite. So far
little
attempt has been made to bridge and span the gap. This is hardly
surprising – sensible scholars think twice before venturing into
two
historiographical minefields simultaneously. Nevertheless the problem of

reconciling these parallel but largely discrete bodies of interpretation
and
evidence remains, and it is one which historians like myself, whose
interests straddle the sixteenth- and seventeenth-century divide and the

Catholic–Protestant confessional fence, can no longer afford to sidestep

and ignore. This essay represents a set of tentative reflections and
speculations on recent research, a cautious exploration of three clusters
of
inter-related issues and themes.
Numerical simulation of turbulent flow in a pipe oscillating around its axis
Authors: QUADRIO MAURIZIO , SIBILLA STEFANO
Published: July 2002

The turbulent flow in a cylindrical pipe oscillating around its longitudinal axis is
studied via direct numerical solution of the Navier–Stokes equations, and compared
to the reference turbulent flow in a fixed pipe and in a pipe with steady rotation. The
maximum amount of drag reduction achievable with appropriate oscillations of the
pipe wall is found to be of the order of 40%, hence comparable to that of similar
flows in planar geometry. The transverse shear layer due to the oscillations induces
substantial modifications to the turbulence statistics in the near-wall region, indicating
a strong effect on the vortical structures. These modifications are illustrated, together
with the implications for the drag-reducing mechanism. A conceptual model of the
interaction between the moving wall and a streamwise vortex is discussed.
A note on single bubble motion in surfactant solutions
Authors: ZHANG YONGQIN , FINCH J. A.
Published: July 2002

This note addresses measurement of single bubble velocity in surfactant solutions
and the physical model of the effect of surfactant concentration on the steady-state
velocity. Continuous tracking of the bubble along the rise path is used as the
measurement method. Using this technique, the steady-state velocity is found to be
independent of surfactant concentration over a wide range, which contradicts the
data frequently used to develop models.
A numerical study of viscoelastic effects in chaotic mixing between eccentric cylinders
Authors: FAN YURUN , TANNER ROGER I. , PHAN-THIEN NHAN
Published: July 2002

In this paper, we are concerned with the effect of fluid elasticity and shear-thinning
viscosity on the chaotic mixing of the flow between two eccentric, alternately rotating
cylinders. We employ the well-developed h-p finite element method to achieve a high
accuracy and efficiency in calculating steady solutions, and a full unsteady algorithm
for creeping viscoelastic flows to study the transient process in this periodic viscoelastic
flow. Since the distribution of periodic points of the viscoelastic flow is not symmetric,
we have developed a domain-search algorithm based on Newton iteration for locating
the periodic points. With the piecewise-steady approximation, our computation for
the upper-convected Maxwell fluid predicts no noticeable changes of the advected
coverage of a passive tracer from Newtonian flow, with elasticity levels up to a
Deborah number of 1.0. The stretching of the fluid elements, quantified by the
geometrical mean of the spatial distribution, remains exponential up to a Deborah
number of 6.0, with only slight changes from Newtonian flow. On the other hand,
the shear-thinning viscosity, modelled by the Carreau equation, has a large impact on
both the advection of a passive tracer and the mean stretching of the fluid elements.
The creeping, unsteady computations show that the transient period of the velocity is
much shorter than the transient period of the stress, and from a pragmatic point of
view, this transient process caused by stress relaxation due to sudden switches of the
cylinder rotation can be neglected for predicting the advective mixing in this time-
periodic flow. The periodic points found up to second order and their eigenvalues
are indeed very informative in understanding the chaotic mixing patterns and the
qualitative changes of the mean stretching of the fluid elements. The comparison
between our computations and those of Niederkorn & Ottino (1993) reveals the
importance of reducing the discretization error in the computation of chaotic mixing.
The causes of the discrepancy between our prediction of the tracer advection and
Niederkorn & Ottino's (1993) experiment are discussed, in which the influence of
the shear-thinning first normal stress difference is carefully examined. The discussion
leads to questions on whether small elasticity of the fluid has a large effect on the
chaotic mixing in this periodic flow.
Destabilization of a vortex by acoustic waves
Authors: LEBLANC STÉPHANE
Published: July 2002

The linear stability of a circular vortex interacting with two plane acoustic waves
propagating in opposite directions is investigated. When the wavelength is large compared
to the size of the vortex, the core is subjected to time-periodic compressions and
strains. A stability analysis is performed with the geometrical optics approximation,
which considers short-wavelength perturbations evolving along the trajectories of the
basic flow. On the vortex core, the problem is reduced to a single Hill–Schrödinger
equation with periodic or almost-periodic potential, the solution to which grows
exponentially when parametric resonances occur. On interacting with the acoustic
waves, the circular vortex is thus unstable to three-dimensional perturbations.
Plume generation in natural thermal convection at high Rayleigh and Prandtl numbers
Authors: LITHGOW-BERTELLONI C. , RICHARDS M. A. , CONRAD C. P. , GRIFFITHS R. W.
Published: July 2002

We study natural thermal convection of a fluid (corn syrup) with a large Prandtl
number (103–107) and temperature-dependent viscosity. The experimental tank (1 × 1 × 0.3m) is heated from below with insulating top and side boundaries, so that the
fluid experiences secular heating as experiments proceed. This setup allows a focused
study of thermal plumes from the bottom boundary layer over a range of Rayleigh
numbers relevant to convective plumes in the deep interior of the Earth's mantle. The
effective value of Ra, based on the viscosity of the fluid at the interior temperature,
varies from 105 at the beginning to almost 108 toward the end of the experiments.
Thermals (plumes) from the lower boundary layer are trailed by continuous conduits
with long residence times. Plumes dominate flow in the tank, although there is a
weaker large-scale circulation induced by material cooling at the imperfectly insulating
top and sidewalls. At large Ra convection is extremely time-dependent and exhibits
episodic bursts of plumes, separated by periods of quiescence. This bursting behaviour
probably results from the inability of the structure of the thermal boundary layer
and its instabilities to keep pace with the rate of secular change in the value of Ra.
The frequency of plumes increases and their size decreases with increasing Ra, and
we characterize these changes via in situ thermocouple measurements, shadowgraph
videos, and videos of liquid crystal films recorded during several experiments. A scaling
analysis predicts observed changes in plume head and tail radii with increasing Ra.
Since inertial effects are largely absent no transition to ‘hard’ thermal turbulence is
observed, in contrast to a previous conclusion from numerical calculations at similar
Rayleigh numbers. We suggest that bursting behaviour similar to that observed may
occur in the Earth's mantle as it undergoes secular cooling on the billion-year time
scale.
Scale-dependent droplet clustering in turbulent clouds
Authors: KOSTINSKI A. B. , SHAW R. A.
Published: July 2002

The current understanding of fundamental processes in atmospheric clouds, such as
nucleation, droplet growth, and the onset of precipitation (collision–coalescence), is
based on the assumption that droplets in undiluted clouds are distributed in space in
a perfectly random manner, i.e. droplet positions are independently distributed with
uniform probability. We have analysed data from a homogeneous cloud core to test
this assumption and gain an understanding of the nature of droplet transport. This
is done by examining one-dimensional cuts through clouds, using a theory originally
developed for x-ray scattering by liquids, and obtaining statistics of droplet spacing.
The data reveal droplet clustering even in cumulus cloud cores free of entrained
ambient air. By relating the variance of droplet counts to the integral of the pair
correlation function, we detect a systematic, scale-dependent clustering signature. The
extracted signal evolves from sub- to super-Poissonian as the length scale increases.
The sub-Poisson tail observed below mm-scales is a result of finite droplet size and
instrument resolution. Drawing upon an analogy with the hard-sphere potential from
the theory of liquids, this sub-Poisson part of the signal can be effectively removed.
The remaining part displays unambiguous clustering at mm- and cm-scales. Failure
to detect this phenomenon until now is a result of the previously unappreciated
cumulative nature, or ‘memory,’ of the common measures of droplet clustering.
An experimental study of the influence of a rotating magnetic field on Rayleigh–Bénard convection
Authors: VOLZ M. P. , MAZURUK K.
Published: July 2002

A destabilizing vertical temperature gradient and a rotating magnetic field have been
applied to a cylindrical column of liquid gallium. The convective flows which arise
as a function of these parameters are identified. For small magnetic field strengths,
a regime of stationary flow is observed. This regime is bounded by critical values
of the Rayleigh and magnetic Taylor numbers. As the rotating magnetic field is
increased, the critical Rayleigh number can increase by more than a factor of 10.
The rotating magnetic field itself induces an instability at a critical value of the
magnetic Taylor number independent of the Rayleigh number. The nature of the
bifurcations (whether subcritical or supercritical) and the convective flows occurring
at the critical Rayleigh numbers are dependent upon the magnetic Taylor number.
For small magnetic Taylor numbers, the experimental observations are consistent
with the occurrence of a single asymmetric meridional roll which is driven around
the cylinder by the rotating magnetic field.
Reappraisal of the Kelvin–Helmholtz problem.

Part 1. Hamiltonian structure
Authors: BENJAMIN T. BROOKE , BRIDGES THOMAS J.
Published: July 2002

This paper and Part 2 report various new insights into the

classic Kelvin–Helmholtz

problem which models the instability of a plane vortex sheet and the

complicated motions arising therefrom. The full nonlinear version of

the hydrodynamic problem is treated, with allowance for gravity and

surface tension, and the account deals in precise fashion with

several inherently peculiar properties of the mathematical model.

The main achievement of the paper, presented in §3, is to

demonstrate that the problem admits a canonical Hamiltonian

formulation, which represents a novel variational definition

of a functional representing perturbations in kinetic energy. The

Hamiltonian structure thus revealed is then used to account

systematically for relations between symmetries and conservation

laws, and none of those examined appears to have been noticed

before. In §4, a generalized, non-canonical Hamiltonian

structure is shown to apply when the vortex sheet becomes

folded, so requiring a parametric representation, as is well

known to occur in the later stages of evolution from

Kelvin–Helmholtz instability. Further invariant properties are

demonstrated in this context. Finally, §5, the linearized

version of the problem – reviewed briefly in §2.1 –

is reappraised in the light of Hamiltonian structure, and it is shown

how Kelvin–Helmholtz instability can be interpreted as the

coincidence of wave modes characterized respectively by positive

and negative values of the Hamiltonian functional representing

perturbations in total energy.
The influence of surface roughness on the particle-pair
distribution function of dilute suspensions of non-colloidal spheres in simple
shear flow
Authors: RAMPALL INDRESH , SMART JEFFREY R. , LEIGHTON DAVID T.
Published: July 2002

The pair distribution function of 3.18 mm diameter particles was
measured in the
plane of shear of a simple shear flow at concentrations of 5%, 10% and 15% by
volume. A new direct flow-visualization procedure and a new pattern recognition
algorithm were used in the investigation. The measurements show a depletion of bound
pairs of particles in the direction of flow. A simple model which includes the
effect of
particle surface roughness on the particle interactions and the pair distribution
function is presented. An important effect of surface roughness is that the
particles in
a suspension can experience irreversible interactions in the presence of
an externally
imposed simple shear flow. The model shows that such irreversibilities eliminate all
bound pairs of particles in the plane of shear by displacing particles out
of the closed
orbit trajectory region. Surface roughness is found to induce significant
asymmetry in
the fore and aft region of a two-particle interaction. The measurements
and predictions
are in qualitative agreement with these conclusions.
Ensemble-averaged measurements in the turbulent near wake of

two side-by-side square cylinders
Authors: KOLÁŘ V. , LYN D. A. , RODI W.
Published: July 2002

The ensemble-averaged characteristics of the turbulent near-wake

flow around two side-by-side identical square cylinders at a Reynolds number

≈23100 have been

studied using a two-component laser-Doppler velocimeter system. The work
focuses

on a single case with a gap/diameter ratio of 2, for which the

resulting individual

vortex streets are coupled so as to yield a flow predominantly symmetric
about

the line midway between the two cylinders. Data sorting or conditioning
according

to phase was performed with the aid of pressure signals taken from taps
on a

sidewall of each cylinder. The two-cylinder results are compared in detail
to results

from a previous study of the one-cylinder case. Vortex structures shed
on the side

towards the flow centreline, termed inner structures, are distinguished
from those

shed on the free-stream side, termed outer structures, and the

differences between the

features associated with the two different structures are examined. The
circulation

associated with outer structures evolves downstream in a manner similar
to that

observed in the one-cylinder case, but the circulation of the inner structures
is

found to decrease dramatically downstream. This not only gives support
to previous

theoretical predictions but also reconciles these with

previously apparently conflicting

experimental observations. Information regarding vortex structure motion
and the

relevant length and time scales is obtained. Differences between momentum
and

vorticity transport, particularly across the flow centreline are

pointed out, and effective

turbulent vorticity fluxes are defined. Similarities in local flow

topologies in one- and

two-cylinder cases are discussed, and the role of local velocity-gradient

invariants and

their relationship to critical points and turbulence statistics are examined.
Lateral straining of turbulent boundary layers.

Part 2. Streamline convergence
Authors: PANCHAPAKESAN N. R. , NICKELS T. B. , JOUBERT P. N. , SMITS A. J.
Published: July 2002

Experimental measurements are presented showing the effects

of streamline convergence on developing turbulent boundary layers. The

longitudinal pressure-gradient

in these experiments is nominally zero so the only extra rate-of-strain

is the lateral

convergence. Measurements have been made of mean flow and turbulence quantities

at two different Reynolds numbers. The results show that convergence leads
to a

significant reduction in the skin-friction and an increase in the boundary
layer

thickness. There are also large changes in the Reynolds stresses with reductions

occurring in the inner region and some increase in the outer flow.

This is in contrast

to the results of Saddoughi & Joubert (1991) for a diverging flow of

the same included

angle and zero pressure-gradient which show much smaller changes in the
stresses and

an approach to equilibrium. A new non-dimensional parameter,

βD, is proposed to

characterize the local effect of the convergence and it is shown how

this parameter is

related to Clauser's pressure-gradient parameter, βx.

It is suggested that this is an

equilibrium parameter for turbulent boundary layers with lateral straining.
In the

present flow case βD increases rapidly with

streamwise distance leading to a significant

departure from equilibrium. Measurement of terms in the transport equations
suggest

that streamline convergence leads to a reduction in production and generation
and

large increases in mean advection. The recovery of the flow after the removal
of

convergence has been shown to be characterized by a significant increase
in the

turbulent transport of shear-stress and turbulent kinetic energy from the

very near-wall

region to the flow further out where the stresses have been depleted by
convergence.
Kidney and anti-kidney vortices in crossflow jets
Authors: HAVEN B. A. , KUROSAKA M.
Published: July 2002

Water tunnel experiments were conducted to examine the effect

of hole exit geometry

on the near-field characteristics of crossflow jets. Hole shapes investigated
were

round, elliptical, square, and rectangular, all having the same cross-sectional
area.

Laser-induced fluorescence (LIF) and particle image velocimetry (PIV) were
used.

The vorticity around the circumference of the jet

was tracked to identify its relative

contributions to the nascent streamwise vortices, which evolve eventually
into kidney

vortices downstream. The distinction between sidewall vorticity and that
from the

leading and trailing edges, though blurred for a round hole,

became clear for a square

or a rectangular hole. The choice of non-circular holes also made it

possible to reveal

the unexpected double-decked structures of streamwise vortices and link
them to the

vorticity generated along the wall of the hole.

The lowermost vortex pair of the double-decked structures,

located beneath the jet, is what we call a ‘steady’ vortex
pair. This

pair is always present and has the same

sense of rotation as the kidney vortices. The origin of these lower-deck

vortices is the hole sidewall boundary layer: as the jet emanates from
the hole,

the crossflow forces the sidewall boundary layer to roll up into nascent

kidney vortices. Here, hole width

sets the lateral separation of these steady sidewall vortices.

The vortices comprising the upper deck ride intermittently over the
top of the

‘steady’ lower pair. The sense of rotation of

these upper-deck vortices depends on

hole geometry and can be the same as, or opposite to, the lower pair.

The origin of the

upper deck is the hole leading-edge boundary layer. This vorticity, initially
aligned

transverse to the crossflow direction, is realigned by the entrainment
of crossflow

momentum and thus induces a streamwise component of vorticity. Depending
on

hole geometry, this induced streamwise vorticity can be opposite to the
lower-deck

vortex pair. The opposing pair, called the ‘anti-kidney’

pair, competes with the nascent

kidney-vortices and affects the jet lift-off. The hole

trailing-edge boundary layer can

likewise be turned toward the streamwise direction. In this case, the

turning is caused

by the strong reverse flow just downstream of the jet.

In the present range of parameters, all hole boundary

layer vorticity, regardless

of its origin along the hole circumference, is found to influence

the kidney vortices downstream.
A numerical investigation of steady convection

in mushy layers during the directional

solidification of binary alloys
Authors: SCHULZE T. P. , WORSTER M. GRAE
Published: July 2002

We present a numerical study of steady convection in

a two-dimensional mushy layer

during the directional solidification of a binary mixture.

The calculations reveal the

internal structure of strongly nonlinear states featuring

upflow which has been focused

into solid-free regions known as chimneys. The mushy layer

is modelled as a porous

medium whose permeability is a function of the local solid

fraction. The mushy layer is

coupled to a chimney that is modelled as a narrow vertical

channel where lubrication

scalings are used to simplify the Navier–Stokes

equations. We use these methods to

exhibit solutions which give the detailed structure of the

temperature, solute, flow

and solid-fraction fields within the mushy layer. A key

finding of the numerics is

that there are two distinct chimney solutions at low

Rayleigh numbers, presumably

corresponding to stable and unstable portions of a

subcritical solution branch. We

also explore the relationship between convective solutions

with and without chimneys.
Inertial and viscous effects on dynamic contact angles
Authors: COX R. G.
Published: July 2002

An investigation is made into the dynamics involved in the movement
of the contact
line when a single liquid with an interface moves into a vacuum over a
smooth solid
surface. In order to remove the stress singularity at the contact line,
it is postulated
that slip between the liquid and the solid or some other mechanism occurs
very
close to the contact line. It is assumed that the flow produced is inertia
dominated
with the Reynolds number based on the slip length being very large. Following
a
procedure similar to that used by Cox (1986) for the viscous-dominated
situation
(in which the Reynolds number based on the macroscopic length scale was
assumed
very small) using matched asymptotic expansions, we obtain the dependence
of the
macroscopic dynamic contact angle on the contact line velocity over the
solid surface
for small capillary number and small slip length to macroscopic lengthscale
ratio.
These results for the inertia-dominated situation are then extended (at
the lowest
order in capillary number) to an intermediate Reynolds number situation
with the
Reynolds number based on the slip length being very small and that based
on the
macroscopic lengthscale being very large.
Instability of thermocapillary–buoyancy convection in shallow
layers.
Part 1. Characterization of steady and oscillatory instabilities
Authors: RILEY R. J. , NEITZEL G. P.
Published: July 2002

Combined thermocapillary–buoyancy convection in a thin rectangular
geometry is
investigated experimentally, with an emphasis on the generation of hydrothermal-wave

instabilities. For sufficiently thin layers, pure hydrothermal waves are
observed,
and are found to be oblique as predicted by a previous linear-stability
analysis (Smith
& Davis 1983). For thicker layers, both a steady multicell state and
an oscillatory
state are found to exist, but the latter is not in the form of a pure hydrothermal
wave.
Driven and freely decaying nonlinear shape
oscillations of drops and bubbles immersed
in a liquid: experimental results
Authors: TRINH E. H. , THIESSEN D. B. , HOLT R. G.
Published: July 2002

Large-amplitude oscillations of drops and bubbles immersed in an
immiscible liquid
host have been investigated using ultrasonic radiation pressure techniques.
Single
levitated or trapped drops and bubbles with effective radius between 0.2
and 0.8 cm
have been driven into resonant shape oscillations of the first few orders.
The direct
coupling of driven drop shape oscillations between the axisymmetric
l=6 and l=3
modes has been documented as well as the interaction between axisymmetric
and
non-axisymmetric l=3 and l=2 modes. Effective resonant
energy transfer from
higher- to lower-order modes has been observed together with a much less
efficient
energy transfer in the reverse direction. The first three resonant modes
for bubbles
trapped in water have also been excited, and mode coupling during driven
and free-decaying
oscillations has been measured. The evidence gathered thus far indicates

that efficient drop resonant coupling between a higher- and a lower-order
mode
occurs when the characteristic frequency of the latter mode roughly coincides
with a
harmonic resonance.
Numerical simulation of superoscillations of a
Triton-bearing drop in microgravity
Authors: CHEN XIAOHUI , SHI TAO , TIAN YUREN , JANKOVSKY JOESEPH , HOLT R. GLYNN , APFEL ROBERT E.
Published: July 2002

Large-amplitude nonlinear oscillations of an axially symmetric
water drop of volume
7.33 cm3, initial aspect ratio 3.4, with surfactant Triton X-100
of
1.4×10−4 g ml−1 (1 CMC), in microgravity
are compared
with predictions of the boundary-integral
method. The small shear viscosity of the bulk phase, as well as the surface
dilatational
viscosity and surface shear viscosity are considered. When a very specific
set of
material properties is assumed, numerical simulations of the drop oscillations
are in
good agreement with the experimental results of drop oscillations measured
in space
during the second United States Microgravity Laboratory, USML-2. The obtained

surface viscosities are in rough agreement with literature values.
Mean-flow scaling of turbulent pipe flow
Authors: ZAGAROLA MARK V. , SMITS ALEXANDER J.
Published: July 2002

Measurements of the mean velocity profile and pressure drop were
performed in a fully
developed, smooth pipe flow for Reynolds numbers from 31×103

to 35×106. Analysis
of the mean velocity profiles indicates two overlap regions: a power law
for
60<y+<500 or
y+<0.15R+, the outer limit
depending on whether the Kármán number R+

is greater or less than 9×103; and a log law for
600<y+<0.07R+. The log law
is only
evident if the Reynolds number is greater than approximately 400×103

(R+>9×103). Von Kármán's

constant was shown to be 0.436 which is consistent with the friction
factor data and the mean velocity profiles for
600<y+<0.07R+, and the additive

constant was shown to be 6.15 when the log law is expressed in inner scaling
variables.

A new theory is developed to explain the scaling in both overlap regions.
This theory
requires a velocity scale for the outer region such that the ratio of the
outer velocity
scale to the inner velocity scale (the friction velocity) is a function
of Reynolds number
at low Reynolds numbers, and approaches a constant value at high Reynolds
numbers.
A reasonable candidate for the outer velocity scale is the velocity deficit
in the pipe,
UCL−Ū, which is a
true outer velocity scale, in contrast to the friction velocity which
is a velocity scale associated with the near-wall region which
is ‘impressed’ on the outer
region. The proposed velocity scale was used to normalize the velocity
profiles in the
outer region and was found to give significantly better agreement between
different
Reynolds numbers than the friction velocity.

The friction factor data at high Reynolds numbers were found to be significantly

larger (>5%) than those predicted by Prandtl's relation. A new
friction factor relation
is proposed which is within ±1.2% of the data for Reynolds
numbers between 10×103 and 35×106,
and includes a term to account for the near-wall velocity profile.
Magnetohydrodynamic convection in molten gallium
Authors: JUEL A. , MULLIN T. , BEN HADID H. , HENRY D.
Published: July 2002

We present the results of an experimental and numerical study of
the effects of
a steady magnetic field on sidewall convection in molten gallium. The magnetic

field is applied in a direction which is orthogonal to the main flow which
reduces the
convection and good agreement is found for the scaling of this effect with
the relevant
parameters. Moreover, qualitatively similar changes in the structure of
the bulk of
the flow are observed in the experiment and the numerical simulations.
In particular,
the flow is restricted to two dimensions by the magnetic field, but it
remains different
to that found in two-dimensional free convection calculations. We also
show that
oscillations found at even greater temperature gradients can be suppressed
by the
magnetic field.
Laboratory observations of wave group
evolution, including breaking effects
Authors: TULIN MARSHALL P. , WASEDA TAKUJI
Published: July 2002

The nonlinear evolution of deep-water wave groups, which are initiated
by unstable
three-wave systems, have been observed in a large wave tank (50 m long,
4.2 m
wide, 2.1 m deep), equipped with a programmable, high-resolution wave generator.
A
large number of experiments were conducted (over 80 cases) for waves 1.0–4.0
m long,
initial steepness ε=0.10–0.28, and normalized sideband
frequency differences, δω=δω,
0.2–1.4. Using an array of eight high-resolution wave wires distributed
in range (up to
43 m fetch), spectral evolution was studied in detail including the effect
of background
disturbances on the evolution. Minimizing those, new observations were
made which
extend the pioneering work of Lake et al. (1977) and of Melville
(1982). Foremost, near
recurrence without downshifting was observed without breaking, despite
a significant
but reversible energy transfer to the lower sideband at peak modulation;
complete
recurrence was prevented by the spreading of discretized energy to higher
frequencies.
Strong breaking was found to increase the transfer of energy from the higher
to the
lower sideband and to render that transfer irreversible. The end state
of the evolution
following strong breaking is an effective downshifting of the spectral
energy, where the
lower and the carrier wave amplitudes nearly coincide; the further evolution
of this
almost two-wave system was not studied here. Breaking during strong modulation

was observed not only for the fastest growing initial condition, but over
a wide
parameter range. An explanation of the sideband behaviour in both the breaking
and
non-breaking case was given based on wave energy and momentum considerations,

including the separate effects of energy and momentum loss due to breaking,
and
transfer to discretized higher frequencies throughout the spectra. Attention
was drawn
to the latter, which was almost universally observed.
Gravity currents descending a ramp in a stratified tank
Authors: MONAGHAN J. J. , CAS R. A. F. , KOS A. M. , HALLWORTH M.
Published: July 2002

This paper describes experiments and numerical simulations of a
gravity current
flowing down a ramp in a tank stratified in two layers. We study the dynamics
of the
configuration for different densities of the gravity current and different
ramp angles.
The experiments show that waves of large amplitude can be generated easily
and that,
depending on the density of the gravity current, the initial gravity current
splits into a
gravity current along the interface of the stratified layers, and a gravity
current along
the bottom of the tank. We also describe numerical simulations which give
results
in agreement with the results of the experiments and enable us to study
three-fluid
configurations with wider ranges of density than is possible in the laboratory.
Radial pulsations of a fluid sphere in a sound wave
Authors: TEMKIN S.
Published: July 2002

This paper presents analytical results for the temperature and
pressure fluctuations
in a droplet or bubble pulsating in a sound wave, the related damping coefficients,
as
well as the corresponding sound attenuation coefficients for dilute suspensions.
The
study is limited to small-amplitude motions but includes the effects of
compressibility
and heat conduction in the fluid outside the particle. Results are obtained
for both
average and surface values of the particle's temperature and pressure
fluctuations
that are applicable to droplets in gases and liquids, and to gas bubbles
in liquids.
In the latter instance, it is found that the bubble's response exhibits
a clear resonant
peak at the isothermal natural frequency, that acoustic radiation is the
dominant
dissipation mechanism near resonance, and that the disturbances produced
by the
bubble in the liquid significantly reduce the thermal damping at most frequencies.

Similar conclusions apply for droplets in liquids, except that the effects
of resonance
are significantly diminished.
Properties of large-amplitude internal waves
Authors: GRUE JOHN , JENSEN ATLE , RUSÅS PER-OLAV , SVEEN J. KRISTIAN
Published: July 2002

Properties of solitary waves propagating in a two-layer fluid are
investigated comparing
experiments and theory. In the experiments the velocity field induced by
the
waves, the propagation speed and the wave shape are quite accurately measured

using particle tracking velocimetry (PTV) and image analysis. The experiments
are
calibrated with a layer of fresh water above a layer of brine. The depth
of the brine
is 4.13 times the depth of the fresh water. Theoretical results are given
for this depth
ratio, and, in addition, in a few examples for larger ratios, up to 100[ratio ]1.
The wave
amplitudes in the experiments range from a small value up to almost maximal
amplitude.
The thickness of the pycnocline is in the range of approximately 0.13–0.26
times
the depth of the thinner layer. Solitary waves are generated by releasing
a volume
of fresh water trapped behind a gate. By careful adjustment of the length
and depth
of the initial volume we always generate a single solitary wave, even for
very large
volumes. The experiments are very repeatable and the recording technique
is very
accurate. The error in the measured velocities non-dimensionalized by the
linear long
wave speed is less than about 7–8% in all cases. The experiments
are compared with
a fully nonlinear interface model and weakly nonlinear Korteweg–de
Vries (KdV)
theory. The fully nonlinear model compares excellently with the experiments
for all
quantities measured. This is true for the whole amplitude range, even for
a pycnocline
which is not very sharp. The KdV theory is relevant for small wave amplitude
but
exhibit a systematic deviation from the experiments and the fully nonlinear
theory
for wave amplitudes exceeding about 0.4 times the depth of the thinner
layer. In the
experiments with the largest waves, rolls develop behind the maximal displacement
of
the wave due to the Kelvin–Helmholtz instability. The recordings
enable evaluation of
the local Richardson number due to the flow in the pycnocline. We find
that stability
or instability of the flow occurs in approximate agreement with the theorem
of Miles
and Howard.
A note on uniqueness in the linearized water-wave problem
Authors: KUZNETSOV N. G. , SIMON M. J.
Published: July 2002

The uniqueness theorem of Simon & Ursell (1984), concerning the linearized two-dimensional water-wave problem in a fluid of infinite depth, is extended in two
directions. First, we consider a two-dimensional geometry involving two submerged
symmetric bodies placed sufficiently far apart that they are not confined in the
vertical right angle having its vertex on the free surface as the theorem of Simon &
Ursell requires. A condition is obtained guaranteeing the uniqueness outside a finite
number of bounded frequency intervals. Secondly, the method of Simon & Ursell
is generalized to prove uniqueness in the axisymmetric problem for bodies violating
John's condition provided the free surface is a connected plane region.