bluuebunny/crossref_metadata_2025_split huggingface dataset:
An experimental study of round jets in cross-flow
Authors: Kelso R. M. , Lim T. T. , Perry A. E. 
Published: April 2006

The structure of round jets in cross-flow was studied using flow visualization techniques and flying-hot-wire measurements. The study was restricted to jet to freestream velocity ratios ranging from 2.0 to 6.0 and Reynolds numbers based on the jet diameter and free-stream velocity in the range of 440 to 6200.Flow visualization studies, together with time-averaged flying-hot-wire measurements in both vertical and horizontal sectional planes, have allowed the mean topological features of the jet in cross-flow to be identified using critical point theory. These features include the horseshoe (or necklace) vortex system originating just upstream of the jet, a separation region inside the pipe upstream of the pipe exit, the roll-up of the jet shear layer which initiates the counter-rotating vortex pair and the separation of the flat-wall boundary layer leading to the formation of the wake vortex system beneath the downstream side of the jet.The topology of the vortex ring roll-up of the jet shear layer was studied in detail using phase-averaged flying-hot-wire measurements of the velocity field when the roll-up was forced. From these data it is possible to examine the evolution of the shear layer topology. These results are supported by the flow visualization studies which also aid in their interpretation.The study also shows that, for velocity ratios ranging from 4.0 to 6.0, the unsteady upright vortices in the wake may form by different mechanisms, depending on the Reynolds number. It is found that at high Reynolds numbers, the upright vortex orientation in the wake may change intermittently from one configuration of vortex street to another. Three mechanisms are proposed to explain these observations.
The effect of free-stream turbulence on sectional lift forces on a circular cylinder
Authors: Blackburn H. M. , Melbourne W. H. 
Published: April 2006

Wind-tunnel experiments were conducted to examine the effect of grid-generated turbulence on lift forces at sections of a circular cylinder. Turbulence of longitudinal intensity between 0.6% and 18% was employed, with cylinder Reynolds numbers in the range 1 × 105to 5 × 105. Addition of low-intensity turbulence had the primary effect of inducing the critical transition at Reynolds numbers below that for smooth flow; above transition there was little difference between the forces experienced by the cylinder in smooth or turbulent flow, with no sign of organized vortex shedding.At higher turbulence intensities effects consistent with a return to organized vortex shedding were observed, particularly for the highest intensity and at the upper end of the Reynolds number range; lift coefficients were greater than in smooth supercritical flow, with a broad spectral peak centred near a Strouhal number of 0.23 accompanied by an increase in spanwise correlation lengths of lift force.
Unsteady transonic nozzle flow of dense gases
Authors: Kluwick A. , Scheichl St. 
Published: April 2006

Vapours of retrograde fluids, i.e. media with large values of the specific heats, may have the remarkable property that sonic conditions are reached three times rather than once during isentropic expansion or compression. As a result, the acceleration of such a fluid through a converging-diverging Laval nozzle under steady flow conditions may lead to the occurrence of an expansion shock discontinuity. Theoretical considerations then suggest that nozzles with two throats should be designed to achieve a full shock-free subsonic-supersonic expansion.In this study the unsteady flow of a dense, retrograde gas through slender nozzles (with one and two throats) is considered. The combination of the Navier-Stokes equations supplemented with a non-classical equation of state for the fluid yields a generalized wave equation, with its validity restricted to flow conditions near the critical value M = 1. This equation is used to study the transition process which sets in if a steady subsonic solution is perturbed by lowering the pressure at the end of the nozzle.
Self-diffusion in sheared suspensions
Authors: Morris Jeffrey F. , Brady John F. 
Published: April 2006

Self-diffusion in a suspension of spherical particles in steady linear shear flow is investigated by following the time evolution of the correlation of number density fluctuations. Expressions are presented for the evaluation of the self-diffusivity in a suspension which is either raacroscopically quiescent or in linear flow at arbitrary Peclet number $Pe = \dot{\gamma}a^2/2D$, where $\dot{\gamma}$ is the shear rate, a is the particle radius, and D = kBT/6πa is the diffusion coefficient of an isolated particle. Here, kB is Boltzmann's constant, T is the absolute temperature, and η is the viscosity of the suspending fluid. The short-time self-diffusion tensor is given by kBT times the microstructural average of the hydrodynamic mobility of a particle, and depends on the volume fraction $\phi = \frac{4}{3}\pi a^3n$ and Pe only when hydrodynamic interactions are considered. As a tagged particle moves through the suspension, it perturbs the average microstructure, and the long-time self-diffusion tensor, D∞s, is given by the sum of D0s and the correlation of the flux of a tagged particle with this perturbation. In a flowing suspension both D0s and D∞ are anisotropic, in general, with the anisotropy of D0s due solely to that of the steady microstructure. The influence of flow upon D∞s is more involved, having three parts: the first is due to the non-equilibrium microstructure, the second is due to the perturbation to the microstructure caused by the motion of a tagged particle, and the third is by providing a mechanism for diffusion that is absent in a quiescent suspension through correlation of hydrodynamic velocity fluctuations.The self-diffusivity in a simply sheared suspension of identical hard spheres is determined to O(øPe3/2) for Pe ≤ 1 and ø ≤ 1, both with and without hydro-dynamic interactions between the particles. The leading dependence upon flow of D0s is 0.22DøPeÊ, where Ê is the rate-of-strain tensor made dimensionless with $\dot{\gamma}$. Regardless of whether or not the particles interact hydrodynamically, flow influences D∞s at O(øPe) and O(øPe3/2). In the absence of hydrodynamics, the leading correction is proportional to øPeDÊ. The correction of O(øPe3/2), which results from a singular advection-diffusion problem, is proportional, in the absence of hydrodynamic interactions, to øPe3/2DI; when hydrodynamics are included, the correction is given by two terms, one proportional to Ê, and the second a non-isotropic tensor.At high ø a scaling theory based on the approach of Brady (1994) is used to approximate D∞s. For weak flows the long-time self-diffusivity factors into the product of the long-time self-diffusivity in the absence of flow and a non-dimensional function of $\bar{P}e = \dot{\gamma}a^2/2D^s_0(\phi)$. At small $\bar{P}e$ the dependence on $\bar{P}e$ is the same as at low ø.
Low Reynolds number fully developed two-dimensional turbulent channel flow with system rotation
Authors: Nakabayashi Koichi , Kitoh Osami 
Published: April 2006

Theoretical and experimental studies have been performed on fully developed twodimensional turbulent channel flows in the low Reynolds number range that are subjected to system rotation. The turbulence is affected by the Coriolis force and the low Reynolds number simultaneously. Using dimensional analysis, the relevant parameters of this flow are found to be Reynolds number Re* = u*D/v (u* is the friction velocity, D the channel half-width) and Ωv/u2* (Ω is the angular velocity of the channel) for the inner region, and Re* and ΩD/u* for the core region. Employing these parameters, changes of skin friction coefficients and velocity profiles compared to nonrotating flow can be reasonably well understood. A Coriolis region where the Coriolis force effect predominates is shown to exist in addition to conventional regions such as viscous and buffer regions. A flow regime diagram that indicates ranges of these regions as a function of Re* and |Ω|v/u2* is given from which the overall flow structure in a rotating channel can be obtained.Experiments have been made in the range of 56 ≤ Re* ≤ 310 and -0.0057 ≤ Ωv/u2* ≤ 0.0030 (these values correspond to Re = 2UmD/v from 1700 to 10000 and rotation number R0 = 2|Ω|D/Um up to 0.055; Um is bulk mean velocity). The characteristic features of velocity profiles and the variation of skin friction coefficients are discussed in relation to the theoretical considerations.
Magnetohydrodynamic flow in a right-angle bend in a strong magnetic field
Authors: Stieglitz R. , Barleon L. , BüHler L. , Molokov S. 
Published: April 2006

The magnetohydrodynamic (MHD) flow through sharp 90° bends of rectangular cross-section, in which the flow turns from a direction almost perpendicular to the magnetic field to a direction almost aligned with the magnetic field, is investigated experimentally for high values of the Hartmann number M and of the interaction parameter N. The bend flow is characterized by strong three-dimensional effects causing a large pressure drop and large deformations in the velocity profile. Since such bends are basic elements of fusion reactors, the scaling laws of magnetohydrodynamic bends flows with the main flow parameters such as M and N as well as the sensitivity to small magnetic field inclinations are of major importance. The obtained experimental results are compared to those of an asymptotic theory.In the case where one branch of the bend is perfectly aligned with the magnetic field good agreement between the results obtained by the asymptotic model and by the experiments was found at high M ≈ 8 × 10 and N ≈ 105 for pressure as well as for electric potentials on the duct surface. At lower values of N a significant influence of inertia has been detected. The pressure drop due to inertial effects was found to scale with N−1/3. The same – 1/3-power dependency on N has been found in the vicinity of the bend for the electric potentials at walls aligned with the magnetic field. At walls with a significant normal component of the field an influence neither of the Hartmann number nor of the interaction parameter has been found. This suggests that the inertial part of the pressure drop arises from inertial side layers, whereas the core flow remains inertialess and inviscid. A variation of the Hartmann number is of negligible influence compared to inertia effects with respect to pressure drop and surface potential distribution. The viscous part of the pressure drop scales with M−½.Changes of the magnetic field orientation with respect to the bend lead in general to different flow patterns in the duct, because the electric current paths are changed. The inertia–electromagnetic interaction determines the magnitude of the inertial part of the pressure drop, which scales with N−1/3 for any magnetic field orientation. The dependence of the pressure drop on M remains proportional to M−½. With increasing M and N the measured data tend to those predicted by the asymptotic model. Local measurements within the liquid metal exhibit discrepancies with the model predictions for which no adequate explanation has been found. But they show that below a critical interaction parameter flow regions exist in which the flow is time dependent. These regions are highly localized, whereas the flow in the rest of the bend remains steady.
Self-similarity of decaying two-dimensional turbulence
Authors: Bartello Peter , Warn Tom 
Published: April 2006

Simulations of decaying two-dimensional turbulence suggest that the one-point vorticity density has the self-similar form
$P_\omega \sim t\;\;f(\omega t)$implied by Batchelor's (1969) similarity hypothesis, except in the tails. Specifically, similarity holds for |ω| < ωm, while pω falls off rapidly above. The upper bound of the similarity range, ωm, is also nearly conserved in high-Reynolds-number hyperviscosity simulations and appears to be related to the average amplitude of the most intense vortices (McWilliams 1990), which was an important ingredient in the vortex scaling theory of Carnevale et al. (1991).The universal function f also appears to be hyperbolic, i.e.
$f(x) \sim c/2\vert x \vert^{1+q_c}$
for |x| > x*, where qc = 0.4 and x* = 70, which along with the truncated similarity form implies a phase transition in the vorticity moments
$\langle \vert \omega\vert ^q\rangle \sim \left\{\begin{array}{ll}
c_q t^{-q}, & -1 < q < q_c\cr
c(q - q_c)^{-1} \omega _m^{q-q_c} t^{-q_c} & q > q_c,
\end{array}\right.$
between the self-similar 'background sea' and the coherent vortices. Here Cq and c are universal. Low-order moments are therefore consistent with Batchelor's similarity hypothesis whereas high-order moments are similar to those predicted by Carnevale et al. (1991). A self-similar but less well-founded expression for the energy spectrum is also proposed.It is also argued that ωc = x*/t represents 'mean sea-level', i.e. the (average) threshold separating the vortices and the sea, and that there is a spectrum of vortices with amplitudes in the range (ωs,ωm). The total area occupied by vortices is also found to remain constant in time, with losses due to mergers of large-amplitude vortices being balanced by gains due to production of weak vortices. By contrast, the area occupied by vortices above afixed threshold decays in time as observed by McWilliams (1990).
Exploring counsellor perceptions of the impact of counselling supervision on clients
Authors: Vallance Kate 
Published: April 2006

AbstractThis qualitative study explores counsellors’ experiences and perceptions of how counselling supervision impacts upon their clients. Data collection combined open‐ended questionnaires (n = 13) and semi‐structured interviews (n = 6). The findings indicate that supervision impacts client work both helpfully and unhelpfully. Areas that emerged as having the most direct impact on client work were the counselling relationship dynamics and self‐awareness, professional development, emotional support, clients not discussed in supervision and the quality of the supervisory relationship. Congruence and confidence were the most direct link between supervision and client work.
Counselling children and young people who attend a school for children with complex needs: A Case Study
Authors: Flitton Beverley , Buckroyd Julia 
Published: April 2006

AbstractWe report the findings of a case study exploring the views of the student, teacher, teaching assistant and counsellor who participated in a project to evaluate counselling with young people who attend a school for children with complex needs in the UK. The student was offered twenty six weeks of humanistic counselling. The student, teacher and teaching assistant were interviewed pre and post counselling using a semi structured format. They were asked about the student's development in the seven areas of self concept which are named in the quantitative scale Piers Harris 2, which was used elsewhere in the project. Data was also gathered from the notes and transcripts of the counselling sessions. The case study describes an approach to the use of language and the counselling process with a student with complex needs. Staff were not able to report any significant changes in the student, yet the student reported a change in herself and an awareness of the process in the counselling relationship and the counsellor identified improvements in communication, self awareness and self confidence.
Making a difference for young people with learning disabilities: A model for inclusive counselling practice
Authors: Pattison Susan 
Published: April 2006

AbstractThe prevalence of mental health problems in young people with learning disabilities and the disability rights movement provide the background to this paper. The aims are to investigate the inclusivity of counselling; gain insight into inclusive practices; and put forward a model for inclusive counselling practice. Mixed methodology provides quantitative and qualitative data through a survey of counsellors (n = 396) and a series of semi‐structured interviews (n = 15). The results produce six indicators of inclusive counselling, which are used to build a model for inclusive counselling practice: proactive approach to inclusion; focus on building relationships; operationalising equal opportunities policies; inclusive initial assessments; adopting flexible and creative approaches to counselling; and training and awareness raising. The implications for research and practice are to acknowledge the exclusive nature of the profession and address the issue of inclusion through training, professional development and further research in the field. The model for inclusive counselling practice is put forward as a tool for auditing existing counselling provision and as guidance for counsellors and policy makers in increasing inclustion of young people with learning disabilities in mainstream counselling.
Dynamical forcing of circular groups
Authors: Calegari Danny 
Published: April 2006

In this paper we introduce and study the notion of dynamical forcing. Basically, we develop a toolkit of techniques to produce finitely presented groups which can only act on the circle with certain prescribed dynamical properties. As an application, we show that the set

X
⊂

R

/

Z

X \subset \mathbb {R}/\mathbb {Z}

consisting of rotation numbers

θ
\theta

which can be forced by finitely presented groups is an infinitely generated

Q

\mathbb {Q}

–module, containing countably infinitely many algebraically independent transcendental numbers. Here a rotation number

θ
\theta

is forced by a pair

(

G
θ

,
α
)

(G_\theta ,\alpha )

, where

G
θ

G_\theta

is a finitely presented group

G
θ

G_\theta

and

α
∈

G
θ

\alpha \in G_\theta

is some element, if the set of rotation numbers of

ρ
(
α
)

\rho (\alpha )

as

ρ
\rho

varies over

ρ
∈
Hom
⁡
(

G
θ

,

Homeo
+

⁡
(

S
1

)
)

\rho \in \operatorname {Hom}(G_\theta ,\operatorname {Homeo}^+(S^1))

is precisely the set

{
0
,
±
θ
}

\lbrace 0, \pm \theta \rbrace

. We show that the set of subsets of

R

/

Z

\mathbb {R}/\mathbb {Z}

which are of the form
\[

rot
⁡
(
X
(
G
,
α
)
)
=
{
r
∈

R

/

Z

|

r
=
rot
⁡
(
ρ
(
α
)
)
,
ρ
∈
Hom
⁡
(
G
,

Homeo
+

⁡
(

S
1

)
)
}
,

\operatorname {rot}(X(G,\alpha )) = \lbrace r \in \mathbb {R}/\mathbb {Z} \; | \; r = \operatorname {rot}(\rho (\alpha )), \rho \in \operatorname {Hom}(G,\operatorname {Homeo}^+(S^1)) \rbrace ,

\]
where

G
G

varies over countable groups, are exactly the set of closed subsets which contain

0
0

and are invariant under

x
→
−
x

x \to -x

. Moreover, we show that every such subset can be approximated from above by

rot
⁡
(
X
(

G
i

,

α
i

)
)

\operatorname {rot}(X(G_i,\alpha _i))

for finitely presented

G
i

G_i

. As another application, we construct a finitely generated group

Γ
\Gamma

which acts faithfully on the circle, but which does not admit any faithful

C
1

C^1

action, thus answering in the negative a question of John Franks.
Prime geodesic theorem for higher-dimensional hyperbolic manifold
Authors: Nakasuji Maki 
Published: April 2006

For a

(
d
+
1
)

(d+1)

-dimensional hyperbolic manifold

M

\mathcal {M}

, we consider an estimate of the error term of the prime geodesic theorem. Put the fundamental group

Γ
\Gamma

of

M

\mathcal {M}

to be a discrete subgroup of

S

O
e

(
d
+
1
,
1
)

SO_e(d+1, 1)

with cofinite volume. When the contribution of the discrete spectrum of the Laplace-Beltrami operator is larger than that of the continuous spectrum in Weyl’s law, we obtained a lower estimate

Ω

±

(

x

d

/

2

(
log
⁡
log
⁡
x

)

1

/

(
d
+
1
)

log
⁡
x

)

\Omega _{\pm }(\tfrac {x^{d/2}(\log \log x)^{1/(d+1)}}{\log x})

as

x
x

goes to

∞
\infty

.
Vision screening in a national sample of ii‐year‐old children
Authors: PECKHAM CATHERINE , ADAMS BRYAN 
Published: April 2006

SUMMARY
This report describes the results of vision screening carried out by local health authorities on a national sample of 11‐year‐old schoolchildren using a standard Snellen‐chart. Of the 12 772 children tested, 78% had an unaided distant visual acuity of 6/6 or better in both eyes (optimal vision), 10% had a distant visual acuity of 6/9 in the worse or both eyes (near‐optimal vision) and 12% had a visual acuity of 6/12 or worse in one or both eyes (definite visual defect). In addition, near visual acuity was tested for 12 737 children and 5% were found to have defective near vision.Glasses had been prescribed for current use in 12% of children but ac quarter of those prescribed glasses did not have them available at the time of the test. Testing revealed that 22% of children whose glasses were available had optimal or near‐optimal unaided distant vision, the number increasing to 68% when retested wearing glasses. In contrast, 43% of the children who were without their glasses had optimal or near‐optimal vision; 27% had a bilateral defect. Amongst the children for whom glasses had not been prescribed 4–6% had a visual defect.A higher proportion of children from non‐manual family background than from manual family background had visual impairment and had been prescribed glasses, but there was no significant social class difference amongst the children with visual defects for whom no glasses had been prescribed.A defect of red/green colour vision was recorded in 6% of boys and 1% of girls. The proportion of children with poor visual acuity was similar in the group of children with defective colour vision and the group with normal colour vision.
Loreto House: a pattern of care
Authors: CHARLTON PETER , FELL RICHARD , HENSHALL ANNE 
Published: April 2006

SUMMARY
This short article is primarily concerned with, what the authors consider to be, two important considerations in any form of residential child care, particularly long‐term:1 The great need for a coherent overall philosophy, which is clearly understood by all members of staff. It is felt that, all too often, assumptions are made about general agreement, which are not necessarily borne out by observed practice.2 The need for the meticulous selection of primary caring staff, followed by relevant in‐service training rather than an overreliance upon, what are sometimes, quite arbitrary qualifications.The article attempts to present a broad profile of a unit which, although it does not claim to represent the ideal, is nonetheless beginning to assume a purposive and identifiable character. The point is made that clinicism, professionalism and academic discussion are important but they are not the only considerations. The children must remain the raison d'être for such a unit, not the justification.The authors hope to have conveyed their conviction that cooperation and communication between the members of a multidisciplinary team presents the most practical and the most productive approach to the care of profoundly and multiply handicapped children.