High Reynolds Channel Flows: Variable curvature

Two-dimensional laminar flow, at high Reynolds number Re, of an incompressible Newtonian fluid in a curved channel connected to 2 fitting tangent straight channels at its upstream and downstream extremities is considered. The Successive Complementary Expansion Method (SCEM) is adopted. This method leads to an asymptotic reduced model called Global Interactive Boundary Layer (GIBL) which gives a uniformly valid approximate solution of the flow field in the whole domain. To explore the effect of the variable curvature on the flow field, the bend has an elliptical median line. The validity of the proposed GIBL model is confronted to the numerical solution of complete Navier- Stokes equations. This comparison includes the wall shear stress which is a very sensitive measure of the flow field. The GIBL results match very well the complete Navier-stokes results for curvatures $K_{max}$ up to 0.4, curvature variations $\vert K'_{max}\vert$ up to 0.7 and eccentricities $e$ up to $\simeq 0.943$ in the whole geometrical domain. The upstream and downstream effects as well as the impact of the curvature discontinuities and the behaviour in the entire bend are well captured by the GIBL model

Nonlinear aspects of high Reynolds number channel flows

This paper considers the flow in a two-dimensional channel at high Reynolds number, with wall deformations which can lead to flow separation. An asymptotic model is proposed by using the successive complementary expansion method with generalized asymptotic expansions. In particular, the model emphasizes the asymmetry of the channel geometry by introducing a change of variables. It is shown that the model is more general than the models developed with the method of matched asymptotic expansions. Comparisons with Navier–Stokes solutions show that the model is well founded and enables us to treat original problems

Uniformly Valid Asymptotic Flow Analysis in Curved Channels

The laminar incompressible flow in a two-dimensional curved channel having at its upstream and downstream extremities two tangent straight channels is considered. A global interactive boundary layer (GIBL) model is developed using the approach of the successive complementary expansions method (SCEM) which is based on generalized asymptotic expansions leading to a uniformly valid approximation. The GIBL model is valid when the non dimensional number μ = δmath is O(1) and gives predictions in agreement with numerical Navier-Stokes solutions for Reynolds numbers Re ranging from 1 to 10 puissance 4 and for constant curvatures δ = math ranging from 0.1 to 1, where H is the channel width and Rc the curvature radius. The asymptotic analysis shows that μ, which is the ratio between the curvature and the thickness of the boundary layer of any perturbation to the Poiseuille flow, is a key parameter upon which depends the accuracy of the GIBL model. The upstream influence length is found asymptotically and numerically to be O(math)

Curved channel flow with stenoses and aneurysms

Curvature is everywhere, in man or nature made devices. Its implication on physiological flows may be as important as other inertial or viscous effects. Relatively to an otherwise straight vessel, the so called centrifugal forces induce secondary flow that modify the whole flow structure and give rise to Dean vortices. Since the pioneering work of Dean many fundamental and applied investigations were performed. More specifically, in the blood dynamics studies, experimental and numerical simulations were also achieved. On the other hand many studies dealt with stenoses or aneurysms mainly situated in otherwise straight vessels. Thus the coupling between the global curvature effects and local section variations due to stenoses or aneurysms is not enough investigated. In the present work we will quantify how the impact of a stenosis or an aneurysm is modified when it occurs in a curved vessel compared to when it is located in a straight environment

El debate sobre las desigualdades contemporáneas: ¿puede excluirse la exclusión social?

This article examines the current scenario of the global crisis. We focus our attention on the mode of organization of contemporary society, which admits inequalities of all kinds, while determines the reactions to this situation. We intend to temper the optimism of the interpretations of inequalities -listed from the side of social exclusion- especially when they are pointed out as anomalies susceptible of being corrected with decisions or moral instructions; also when their dynamical and multi-dimensional character, are reduced to poverty or wealth distribution issues. It is concluded that inequalities have multiplied and are determined by the forms that the structures of society have taken on; at the same time, explain how globally, or from their different systems, these inequalities are not acceptable and it is anticipated that their demands to political system will increase, requiring it's overcoming or contention.El presente artículo examina el escenario actual de la crisis mundial. Concentra nuestra atención la modalidad de organización de la sociedad contemporánea que, admite desigualdades sociales de todo tipo, mientras determina las reacciones frente dicha situación. Se propone moderar el optimismo de las interpretaciones sobre las desigualdades -indicadas desde el lado de la exclusión social-, especialmente cuando se las señala como anomalías corregibles con decisiones o instructivos morales; también cuando se descuida su carácter dinámico y multidimensional, reduciéndolas a temas de pobreza o de distribución de riqueza. Se concluye que las desigualdades se han multiplicado y están determinadas por las formas que han asumido las estructuras de la sociedad; al mismo tiempo, explicamos cómo globalmente, o desde sus distintos sistemas, esas desigualdades no son aceptables y se anticipa que aumentaran las demandas hacia el sistema político exigiendo su superación o contención

High Reynolds Channel Flows: Upstream interaction of various wall deformations

The flow at high Reynolds number in the entrance of distorted channel is considered. We analyse the anticipated fluid responds to a downstream wall distortion, and we find that the non linear upstream length \Delta={\mbox{O}}(R_e^{1/7}), using either a new asymptotic approach called Successive Complementary Expansions Method (SCEM) with generalized asymptotic expansions and a modal analysis of the perturbed flow. Comparisons with Navier-Stokes solutions show that the mathematical model is well founded

The flow structure behind vortex generators embedded in a decelerating turbulent boundary layer

The objective of the present work is to analyse the behaviour of a turbulent decelerating boundary layer under the effect of both passive and active jets vortex generators (VGs). The stereo PIV database of Godard and Stanislas [1, 2] obtained in an adverse pressure gradient boundary layer is used for this study. After presenting the effect on the mean velocity field and the turbulent kinetic energy, the line of analysis is extended with two points spatial correlations and vortex detection in instantaneous velocity fields. It is shown that the actuators concentrate the boundary layer turbulence in the region of upward motion of the flow, and segregate the near-wall streamwise vortices of the boundary layer based on their vorticity sign

Ruled By Venus

The following report contains a plan for the creation of and marketing of my own brand, Ruled By Venus. The report describes plans for brand development, segmentation and targeting, competition research, positioning, and social media marketing. All of the clothes seen in this report were designed and sewed by me. My passion for creative, sustainable fashion is the foundation for this brand

A comunicação genetica do perspective dos sistemas sociais

In this article social system theory was applied in order to analyze the repercussions of bioscientific applications in contemporary society, and furthermore in order to explain the risk status of a habitual means of communication. From this perspective, genetic research is treated as an emerging problem one, which is self-made, that aims at situations which Latin American society has only just recently begun to face. The objectives of this study were to relate, from an observation of the second order, reports that were from genetically modified foodstuffs to the expectations generated by genetics research. Finally, this article indicates that the complexity is raised in social operations which will involve communication in genetics, communication that will guide its evolution, as is the case with communication in Bioethics.En este artículo se aplica la teoría de los sistemas sociales para analizar las repercusiones de las aplicaciones biocientíficas en la sociedad contemporánea y explicar el posicionamiento del riesgo como un medio habitual de comunicación. Desde esta perspectiva, trata la investigación genética como un problema emergente y autoproducido, que apunta a situaciones que las sociedades latinoamericanas recién empiezan a enfrentar. Los objetivos fueron relacionar, desde una observación de segundo orden, comunicaciones que van desde los alimentos transgénicos hasta las expectativas generadas por la investigación genómica. Finalmente, se indican los medios que incrementan en complejidad las operaciones sociales involucradas en la comunicación genética y que guían su evolución, como es el caso de la comunicación bioética.Este artigo aplica a teoria dos sistemas sociais para analisar as repercussões das intervenções biotecnocientíficas na sociedade contemporânea; busca, também, explicar o posicionamento do risco como meio habitual de comunicação. Nessa perspectiva, considera a investigação genética como problema emergente e autoproduzido que aponta para situações que as sociedades latinoamericanas apenas começam a enfrentar. Os objetivos são de relacionar as comunicações relativas ao espectro que vai dos alimentos transgênicos até as expectativas geradas pela investigação genômica. Finalmente, apontam-se os meios que aumentam em complexidade as operações sociais envolvidas na comunicação genética e que orientam sua evolução, como é o caso da comunicação bioética

DIVERSIDAD Y EDUCACIÓN INTERCULTURAL

Este artículo contiene breves reflexiones en torno a la diversidad cultural y a la educación intercultural. Se refiere a los conflictos latentes que se desprenden del hecho que la diversidad cultural no ha constituido base para la construcción de las instituciones políticas de la modernidad. Esto conlleva una escalada de exclusiones entre las cuales se destaca la ausencia de discusión pública, en los diversos estamentos sociales, sobre derechos y/o condiciones de grupos étnico-culturales. Mayorías etnoculturales, igualmente, no demandan su visibilidad. Se plantea el tratamiento de la diversidad e identidades culturales develando sus limitaciones a través de tres aproximaciones: (1) las consecuencias perversas del supuesto que el vínculo cultural sostiene la unidad de la sociedad, en estados soberanos; (2) el conceptualizar identidad cultural como revitalización de prácticas ancestrales. Las estrategias y motivaciones de los movimientos responden más bien a condiciones de la globalización y efectos de programas económicos; (3) partir del supuesto que la constitución de estados-nacionales es un recurso para alcanzar reconocimiento pleno de un grupo etnocultural, es incongruente con la internalización de organizaciones poderosas, entre otros factores