1,720,953 research outputs found
A new correlation of average temperature and maximum heat flux for turbulent supersonic flow in a large size channel up to Mach 5
No full textSupersonic compressible turbulent flow through a large size channel is studied numerically. The flow is modeled by the Favre averaged Navier-Stokes (FANS) equation with k−ω as turbulence model, the resulting governing equations are solved by employing an in-house unsteady state density based solver developed using sixth order accuracy compact finite difference schemes. The effect of Mach number and different wall thermal boundary conditions influencing, the variation of velocity, temperature and density across the channel height are reported in the present study. In the present study, the height of the channel is considered as 10 mm and the bulk Reynolds number is in the range of 3.42×105 to 1.14×106 which is higher compared to previous studies. Furthermore, the present Reynolds number represents a fully turbulent flow scenario, common in many aerospace applications. The results indicate that for an adiabatic wall with higher Mach number, there is a substantial increase in the wall temperature. The flow characteristics for a heated wall carried at low and medium Mach numbers indicate that for higher wall temperature, the behaviour of flow characteristics shifts towards that of the adiabatic wall behaviour. However, for higher Mach numbers the flow characteristics behaves like that of isothermal wall condition. In the present work, mathematical correlations for average temperature and maximum heat flux based on the Mach number are developed for adiabatic and isothermal wall conditions, respectively. The present results are validated with direct numerical simulation (DNS) results reported in the literature
Numerical investigation of aerospike semi-cone angle and a small bump on the spike stem in reducing the aerodynamic drag and heating of spiked blunt-body: New correlations for drag and surface temperature
No full textAerodynamic drag and heat reduction effectivity of the aerospike attached to the blunt-body at various aerospike semi-cone angles (θ S), lateral injection from the aerospike stem, and a small bump on the aerospike stem, at different Mach number is numerically investigated. An open-source computational fluid dynamics code, i.e., rhoCentralFoam, a density-based solver in OpenFOAM is employed to solve the governing equations of supersonic turbulent flow. Menter's two-equation turbulence model, i.e., k - ω shear stress transport model is employed for turbulence modeling. A significant reduction in the total drag force (T D f) on the blunt-body is observed with the increase in aerospike θS at a fixed spike length (L)/blunt-body diameter (D) ratio for Mach 2 and 5. With the increase in θ S > 15 ° for L/D = 1 and θ S > 10 ° for L/D = 2, a significant decrease in the magnitude of coefficient of pressure is observed for Mach 5. Results show a maximum percentage reduction of 23.611% and 61.414% in TDf at L/D = 2 and θ S = 45 ° for Mach 2 and 5, respectively. Correlations are developed for the estimation of total drag force on the blunt-body and average surface temperature of the nose at Mach 2 and 5. Lateral injection substantially improves the aerodynamic heat reduction capability of the aerospike owing to the rapid expansion of the injectant in the main flow. An alternate passive technique (a small bump on the spike stem) capable of producing higher aerodynamic drag reduction compared to the active technique (i.e., lateral injection) is proposed. The small bump on the spike facilitates an early initiation of boundary layer separation and leads to the formation of a large recirculation zone ahead of the nose. Results indicate a higher reduction in aerodynamic drag with the increase in bump height (H B) compared to lateral and no injection at Mach 2 and 5. Present results have been validated with the experimental results available in the literature. © 2021 Author(s)
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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