1,721,069 research outputs found
Simulation strategies for complex turbulent flows
No full textComputational fluid dynamics in conjunction with the Reynolds-Averaged Navier-Stokes approach is nowadays routinely employed in a large variety of engineering andindustrial applications despite some well-known reliability issues in more complex flows. In this study, the performance of a state-of-the-art Explicit-Algebraic-StressModel (EASM) and a promising elliptic-blending approach is assessed on a range of test cases to predict complex turbulent flows. In an attempt to improve the quality of the predictions, near-wall-anisotropy modifications are introduced to the EASM, which provide better predictions for the Reynolds-stress and anisotropy tensor close to solid walls. In addition, a novel elliptic-blending RANS model is presented, which is based on the inverse turbulence time scale w, and which is equipped with a non-linear constitutive stress-strain relationship. The coefficients of the non-linear stress-strain relationship are obtained from the explicit solution of a Second-Moment Closure in the limit of weak equilibrium, and by imposing an internal consistency constraint and near-wall-anisotropy modifications, such that the highly anisotropic state of turbulence and the limiting two-component state is correctly reproduced at solid boundaries. The performance of the modified EASM and the novel elliptic-blending model are illustrated and assessed for a range of complex turbulent flows. It is expected that, due to ever increasing computational resources, unified or hybrid RANS/LES approaches will slowly penetrate into engineering applications where improved accuracy and reliability is needed. For this reason, a unified RANS/LES/DNS framework is presented, which is expected to provide the required amount of turbulence modelling for any mesh resolution and seamlessly operates between RANS and DNS mode. This is achieved by a revised Flow Simulation Methodology where the turbulence modelling contribution of a RANS model is rescaled using a damping function. The Flow Simulation Methodology is operating in conjunction with a newly developed damping function and a tailored convection discretisation scheme. In addition, a thorough calibration study is performed, which ensures proper turbulence resolving capabilities. It is conjectured that a sophisticated RANS model will also improve the overall quality of the predictions of any hybrid RANS/LES model. For this reason, the new elliptic-blending RANS model is incorporated, together with two successively simpler turbulence models, into the unified RANS/LES/DNS framework and the performance are assessed on a range of test cases, and compared to other widely used hybrid RANS/LES methods
Applicability of RANS models for accurate computation of flow over airfoils with serrated trailing edges
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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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Carsharing Business Model Optimization – A Comparative Analysis of Consumer Demands and Market Offerings for Market Strategy Transformation
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