1,721,051 research outputs found
Non-equilibrium near wall velocity profiles in the flow around a cylinder mounted on a flat plate
No full textWe consider fully turbulent flow around a cylinder mounted on a flat plate. We performed a highly resolved Large Eddy Simulation using zonally refined grids around the cylinder and a fully turbulent inflow condition. The flow is characterized by strongly non-equilibrium near wall velocity profiles which deviate from the equilibrium law of the wall. We assess the prediction of wall shear stresses in those regions which has an impact on wall modeling and prediction of erosion and scour development
Near Wall PIV-Measurements on the Windward Slope of a Hill
No full textThe turbulent flow over periodic hills was measured near to the wall, using planar Particle-Image-Velocimetry (PIV) at high spatial resolution. Our focus is on the near wall turbulence structure on the windward slope of the hill. For large-eddy simulation (LES) we suspect that, if this was not predicted accurately, it affects the prediction of the velocity profiles over the hill crest which in turn will affect the recirculation length downstream of the hill. Regarding the time averaged velocities, we were able to resolve the linear viscous region of the boundary layer. The velocity distribution and also the Reynolds stress does not comply with the law of the wall as it is valid for a turbulent boundary layer at equilibrium
Uncertainty of noise porediction in case of flow over a over forward-facing step
No full textThe demand of development and application of computational aeroacoustic (CAA) prediction tools for turbulence related noise is increasing to overcome the future requirements of low noise design. Fast and accurate prediction methods are necessary to be integrated into early design processes. Several numerical and experimental studies show that the complex flow physics even of simple geometries is still not fully understood. A great interest is the identification and quantification of noise sources. Hence, immense effort has to be spent for a detailed investigation of the capability of experimental and numerical methods with respect to industrial applications. In this context the uncertainty analysis of aeroacoustic computation is a key issue for the evaluation of low-noise design
Analysis and low order modeling of the inhomogeneous transitional flow inside a T-mixer
No full textA direct numerical simulation of the transitional flow (Re=300 to Re=700) inside a T-mixer configuration has been carried out. Time records were collected and used to perform a proper orthogonal decomposition (POD) of the flow. Changes of the flow characteristics in the frequency spectra and extracted coherent spatial structures indicate flow transition across the investigated Reynolds numbers. The POD modes were used to derive a low-order model of the flow. An a priori test limits the possibilities of the modeling; for the periodic case it demonstrates that the flow can be reduced to a system of a few degrees of freedom, while for the turbulent ones this results to be extremely difficult because of the large number of degrees of freedom that are necessary to describe the flow
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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