Turbulent structures in smooth and rough open channel flows: effect of depth

In this thesis, detailed experiments are performed to study the effect of the flow depth on turbulent structures in smooth and rough bed open channel flow. When the rough bed is introduced in the shallow flow, the local turbulence near the roughness element intensifies and becomes highly heterogeneous. The model roughness under study consists of a train of two dimensional square ribs spanning the whole length of the channel. The height of the ribs (k) occupy 10-15% of the depth of flow (d) and falls in the category of large roughness. Velocity measurements were conducted using laser Doppler velocimetry (LDV) and particle image velocimetry (PIV) systems. While on the smooth bed, mean velocity scaling in the classical logarithmic format was confirmed from the present experiments, for the deep-flow cases, turbulence quantities were found to be influenced by the free surface. A modified length scale based on a region of constant turbulence intensity is proposed to account for the effect of the free surface. Two-dimensional PIV measurements were made in the streamwise-wall normal plane of the smooth open channel flow at d = 0.10 m and Red = 21,000 to further study the influence of the free surface on the turbulent structures. Proper orthogonal decomposition (POD) and swirling strength analysis were employed to investigate the structures present in the flow. Analysis of the POD reconstructed velocity fields reveals the presence of large-scale energetic structures near the free surface

Particle Image Velocimetry (PIV) Investigation of Local Scour Around Emergent and Submerged Circular Cylinders

Analysis of the velocity field surrounding a circular cylinder under equilibrium of local scour has been restricted due to practical limitations of commonly used measurement techniques. This investigation summarizes select cases in the literature which have attempted to circumvent such limitations and presents flow field measurements using Particle Image Velocimetry (PIV). Scour tests were conducted in a horizontal flume fitted with a sediment recess containing erodible bed material. Tests were conducted with both emergent and submerged circular cylinders for a period of 24 hours, after which equilibrium was achieved and planar PIV measurements were obtained in the streamwise-vertical symmetry plane. Analysis of bed profiles and the distribution of the mean velocity indicated that the scour depth upstream of the cylinder was slightly (2 percent) higher for the emergent case, and separation of flow over the top of the submerged cylinder affected the formation of the dune in the wake of the cylinder

Assisting Communities to Access EU Funds for Inclusion

National governments in Europe can greatly enhance the implementation of their National Roma Integration Strategies and social inclusion more broadly. One proven way of doing this is by providing assistance to local authorities and organizations to access and implement projects financed by European Structural and Investment Funds.The Making the Most of EU Funds for Roma Program of the Open Society Foundations has worked for more than five years with local communities to leverage EU funds for social inclusion projects targeting Roma, as well as other disadvantaged communities. This paper summarizes the experiences and methodologies employed by the program, bearing in mind that national authorities—particularly in new member states benefiting from Structural Funds—might be keen to replicate a similar model to advance their own social inclusion goals.National governments can establish similar support mechanisms for local communities in order to intensify local spending of EU funds for social inclusion. This assistance is most relevant for EU Member States with sizeable Roma communities including Bulgaria, Czech Republic, Hungary, Romania, and Slovakia

Scaling up Roma Inclusion Strategies Truth, reconciliation and justice for addressing antigypsyism. Study. Study requested by the LIBE committee. CEPS Special Report, February 2019

This study, commissioned by the European Parliament’s Policy Department for Citizens’ Rights and Constitutional Affairs at the request of the LIBE Committee, aims to promote a better understanding of the Roma minority and communities’ situation in the EU. The study explores concrete proposals to upscale the post-2020 Roma framework strategy via a Rule of Law, Democracy and Fundamental Rights (DRF) Periodic Review/Mechanism and a Truth and Reconciliation Process at the EU level. It proposes ways to strengthen the role of the European Parliament in ensuring democratic accountability and the right to truth and effective justice for past and current human rights violations

Optimised mixing and flow resistance during shear flow over a rib roughened boundary

A series of numerical investigations has been performed to study the effect of lower boundary roughness on turbulent flow in a two-dimensional channel. The roughness spacing to height ratio, w/k, has been investigated over the range 0.12 to 402 by varying the horizontal rib spacing. The square roughness elements each have a cross-sectional area of (0.05 H)2, where H is the full channel height. The Reynolds number, Reτ is fixed based on the value of the imposed pressure gradient, dp/dx, and is in the range 6.3 × 103 − 4.5 × 104. A Reynolds Averaged Navier–Stokes (RANS) based turbulence modelling approach is adopted using a commercial CFD code, ANSYS-CFX 14.0. Measurements of eddy viscosity and friction factor have been made over this range to establish the optimum spacings to produce maximum turbulence enhancement, mixing and resistance to flow. These occur when w/k is approximately 7. It is found that this value is only weakly dependent on Reynolds number, and the decay rate of turbulence enhancement as a function of w/k ratio beyond this optimum spacing is slow. The implications for heat transfer design optimisation and particle transport are considered

The Art of Pleasing the Eye : Portraits by Nicolas de Largillierre and Spectatorship with Taste for Colour in the Early Eighteenth Century

This study examines the interaction between portraits by the exponent of French colourist painting Nicolas de Largillierre (1656–1745) and elite spectatorship in the early eighteenth century as enactment of the idea of painting as an art of pleasing the eye. As developed in the theory of art of Roger de Piles (1635–1709), the idea of painting as an art of pleasing the eye coexisted with the classicist view, which in turn emphasised the potential of painting to communicate discursive meanings and hence to engage the mind. The idea of painting as an art of pleasing the eye was associated with a taste that valued the pictorial effects of painting and related to the ideal of honnêteté, which expanded on the art of pleasing in polite society by means of external appearances as a sign of social distinction. The aim of the study is to explore how portraits by Nicolas de Largillierre address the spectator and how such paintings might have come to have meaning for spectators in the early eighteenth century. To do this, the study takes a performative approach and defines meaning as a product of the interplay of pictorial effects and spectatorial response, progressing from the initial encounter throughout the sustained exploration of the paintings. Building on close analyses of selected paintings and readings of texts that bear on issues of pictorial imitation, spectatorship and social interaction, the study brings into focus the interplay of cognitive and sensory activities, including verbal articulation and bodily movement, which come into play in the production of meanings through the act of spectatorial experience. The study also emphasises the interplay of the mimetic and the material aspects of the paintings as an important bearer of meanings and identifies several interrelated sites of tension in which the pictorial effectiveness of the portraits resides. The study concludes by suggesting that to infer such meanings, the spectator should be prepared to respond to the address of the paintings actively, by engaging the mind, the senses and the body. Such an interpretation of the interaction between portrait paintings and spectators proposes a complex view of the ways in which artistic and spectatorial practices in the early eighteenth century might have interacted to create meanings while reproducing at the same time social and aesthetic conventions and ideals, such as the art of pleasing the eye.Fulltexten går inte att ladda ned eller att skriva ut pga upphovsrättslliga skäl. Går endast att läsa på skärmen.</p

Turbulence structure of non-uniform rough open channel flow

This paper focuses on the turbulence structure in a non-uniform, gradually varied, sub-critical open channel flow (OCF) on a rough bed. The flow field is analysed under accelerating, near-uniform and decelerating conditions. Information for the flow and turbulence parameters was obtained at multiple sections and planes using two different techniques: two-component laser Doppler velocimetry (LDV) and particle image velocimetry (PIV). Different outer region velocity scaling methods were explored for evaluation of the local friction velocity. Analysis of the mean velocity profiles showed that the overlap layer exists for all flow cases. The outer layer of the decelerated velocity profile was strongly affected by the pressure gradient, where a large wake was noted. Due to the prevailing nature of the experimental setup it was found that the time-averaged flow quantities do not attained equilibrium conditions and the flow is spatially heterogeneous. The roughness generally increases the friction velocity and its effect was stronger than the effect of the pressure gradient. It was found that for the decelerated flow section over a rough bed, the mean flow and turbulence intensities were affected throughout the flow depth. The flow features presented in this study can be used to develop a model for simulating flow over a block ramp. The effect of the non-uniformity and roughness on turbulence intensities and Reynolds shear stresses was further investigated