1,720,969 research outputs found
Dataset supporting the paper "Scalar transport in flow past finite circular patches of tall roughness".
No full textThis archive contains the minimal dataset necessary to reproduce the plots reported in the paper "Scalar transport in flow past finite circular patches of tall roughness", (2023), Int. J. Heat Fluid Flow 102:109167 (DOI: 10.1016/j.ijheatfluidflow.2023.109167). Data for all figures, as well as scripts necessary to reproduce these, are included in the archive.</span
Dispersion over multiscale rough patches
No full textIn this work, we experimentally investigate the effect of a multiscale patch of roughness on the dispersion of a passive scalar near the ground. Passive fluorescent dye is released from a ground level point source upstream of the patch in a boundary layer that is naturally developing in a water tunnel. Planar laser-induced fluorescence (PLIF) and particle image velocimetry (PIV) are used to carry out measurements of concentration and velocity in the domain downstream of the point source. The spread of the mean concentration distributions for several different patches are compared with the smooth wall case to investigate the effect of patch solidity. These effects are then related to measurements of the internal boundary layer of the patch’s wake.</p
Time-averaged velocity and scalar fields of the flow over and around a group of cylinders: a model experiment for canopy flows
No full textWe conduct a well-controlled model experiment for a wide variety of canopy flows. Examples of these include engineering flows such as wind flow, dispersion of scalars through and over urban areas, and the convective heat transfer in many heat exchangers, as well as natural canopies such as flows through terrestrial or aquatic vegetation. We aim to shed the light on fundamental flow and transport phenomena common to these applications. Specifically, the characteristics of mean flow and scalar concentration characteristics of a turbulent boundary layer flow impinging on a canopy, which comprises a cluster of tall obstacles (this can also be interpreted as a porous obstruction). The cluster is created with a group of cylinders of diameter d and height h arranged in a circular patch of diameter D . The solidity of the patch/obstruction is defined by ϕ (the total planar area covered by cylinders), which is systematically varied ( 0.098≤ϕ≤1 ) by increasing the number of cylinders in a patch ( Nc ). A point source is placed at ground level upstream of the patch and its transport over and around the patch is examined. Time-averaged velocity and scalar fields, obtained from simultaneous planar particle image velocimetry-planar laser-induced fluorescence (PIV-PLIF) measurements, reveal that the characteristics of wake and flow above porous patches are heavily influenced by ϕ . In particular, we observe that the horizontal and vertical extent of the wake and scalar concentration downstream of the patches decreases and increases with ϕ , respectively. Here, the recirculation bubble is shifted closer to the trailing edge (TE) of the patches as ϕ increases, limiting the flow from convecting downstream, decreasing the scalar concentration and virtually ‘extending’ the patch in the streamwise direction. As the bubble forms in the TE, vertical bleeding increases and hence the concentration increases above the patch where the cylinders appear to ‘extend’ vertically towards the freestream.<br/
Inertial particles in homogeneous shear turbulence: Experiments and direct numerical simulation
Full text linkThe properties of the transport of heavy inertial particles in a uniformly sheared turbulent flow have been investigated by combining experimental and numerical data at particle Stokes number St ≈ 0.3 ÷ 0.5 respectively. As in isotropic turbulence, particles are observed to avoid zones of intense enstrophy and to cluster in strain-dominated regions, resulting in highly intermittent spatial distributions. Moreover, the anisotropy of the mean flow is found to imprint a clear preferential orientation of the particle clusters in the direction of the maximum mean strain. These features are observed both in the numerics and in the experiments, and have been consistently quantified by a number of complementary statistical tools, such as the Voronoï tessellations and the pair correlation function. The latter quantity has been generalized in the form of the Angular Distribution Function and has allowed to evaluate the anisotropy content of the particle field at each scale. The behavior of this observable exhibits the same trend in the two datasets and suggests that, owing to increased inertia, the particle distribution starts to recover isotropy at scales smaller than the carrier velocity field. A proper rescaling of the two datasets in terms of their respective values of the shear scale allows to account for differences in the Reynolds number of experiments and numerics in the range of scales dominated by the mean shear. © 2013 Springer Science+Business Media Dordrecht
Dataset for: Wakes of wall bounded turbulent flows past patches of circular cylinders
No full textThe .txt files in the compressed .rar file here contain data to reproduce figures that appear in the paper: C. Nicolai , S. Taddei, C. Manes and B. Ganapathisubramani, "Wakes of wall-bounded turbulent flows past patches of circular cylinders", doi:10.1017/jfm.2020.102.
If you use this data, please cite the above mentioned paper as well as the preceding work that used this dataset: "Characterisation of drag and wake properties of canopy patches immersed in turbulent boundary layers"
S. Taddei, C. Manes and B. Ganapathisubramani, DOI: 10.1017/jfm.2016.312.</span
Wakes of wall-bounded turbulent flows past patches of circular cylinders
No full textThe properties of the wake generated by a porous body fully immersed in a turbulent boundary layer are experimentally assessed. The body consists of an array of cylinders, with diameter d, covering a circular patch of diameter D. For fixed d and D, by increasing the number of cylinders, Nc, within the patch, the wake properties are systematically tested under different levels of density (ϕ = covered planar area per total surface) and compared to the flow past a solid body of equivalent diameter and height (H). Some insights on the complex flow developing in the wake are captured: ϕ varying in the range (2−24)% results in the flow meandering among the cylinders and bleeding from the top, the sides and the trailing edge of the patch. The interplay between trailing edge and top bleeding prevents wake entrainment, locking the wake longitudinal extent to 5-7 patch diameters, regardless of the density level. Due to the finite body vertical extent, a third shear layer develops from the top of the patch. The interaction between the top shear layer and the lateral ones leads to a mutual alteration, namely a non-linear growth not captured by the classical mixing layer theory. Nevertheless, on the horizontal plane at the patch mid height, the mean flow recovers exhibiting a self-similar decay. Surprisingly, the recovery is well described by the classical planar wake theory and the characteristics scales, namely the maximum velocity deficit and the wake half width, evolve linearly as proposed by Wygnanski et al. (1986)
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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