1,720,969 research outputs found
Racing Car Airbox Performance Prediction Using LES Simulation Approach
No full textThis paper deals with the assessment of the use of LES
simulation technique on a real airbox geometry designed
for a high-performance engine.
Large Eddy Simulation is a promising technique to yield a
CFD tool able to predict flow unsteadiness: in LES
modeling only a small part of the energy spectrum is
modeled while the large scales of motion (correlated with
the energy transport phenomena) are directly resolved.
Given this observation, LES model becomes a very
attractive tool for the fluid dynamic analysis of
components characterized by a strong dynamic flow
behavior like an airbox geometry.
The airbox simulations were performed by Fluent v6.3
CFD code and the Wall Adaptive Local Eddy-Viscosity
(WALE) sub-grid (sgs) stress model was used. A
bounded second order central differencing scheme
(BCD) was adopted and a discussion of the kinetic
energy conservation attitude of this scheme was
performed.
In order to perform a reliable airbox LES simulation, the
computational domain was constructed on the basis of a
classic experimental test bench flow layout used to test
the airbox performance. Results obtained by LES
simulations were analyzed in terms of mean evolution
and rms fluctuations of both pressure and velocity
components.
The numerical results obtained from the LES simulation
showed as this simulation approach could be used to
clearly understand the dynamic interaction between
airbox flow behavior and flow conditions on the inlet
trumpet sections and to optimize the airbox layout. It is
concluded that, today, LES technique is being a very
proficient approach to obtain a high fluid dynamic
resolution level on industrial cases
Toward the Use of LES in Industrial Application
No full textReciprocating engine development toward better performance (less consumption and/or raw
gaseous emissions) is asking for more accurate tools of investigation. During the last years,
the Computational Fluid Dynamic (CFD) approach has become one of the most used
numerical tool to study the fluid dynamic behaviour of Internal Combustion Engines (ICE)
and to optimise their thermo physical behaviour. In particular, recently, thanks to computer
evolution, the application and the development of Large Edddy Simulatio (LES) methods to
reciprocating Internal Combustion Engine have become stronger and wider since their
potential have become clear. With respect to RANS approach, LES approach is expected to
be successful in predicting momentum transfer since the rate controlling-processes are
dominated by the large scales of motion thus, most of the large scale unsteadiness is directly
solved. LES characteristics make this approach a strong candidate to be an unavoidable tool
to perform detailed fluid dynamic analysis of unsteady flows inside ICE. Nevertheless, for a
LES simulation an accurate numerical set-up must be performed in order to achieve accurate
and grounded numerical results.
This paper would contribute in bridging LES toward industrial application showing
capabilities, potential and limits.
The aim of this paper is to present the application of the LES simulation approach for the
analysis of a real airbox flow of an high performance race car. High performance race car
efficiency is based on a very fine equilibrium between aerodynamic efficiency, engine
performance and chassis behaviour. In order to maximize the overall performance of a
naturally aspirated engine, it is necessary to optimise the boosting capability of the air box. It
must be noted that air box must convert the external flow dynamic pressure into static
pressure thus increasing the air density available over trumpets. Moreover it should minimize
the unsteady effects induced by the intake process of each cylinders by a proper design.
Thus as a first step of the development, the air box is analysed under “steady” flow
conditions, checking its capability to increase air density from the ambient value taken as
reference. The airbox simulations consider a non-reactive flow in a fixed grid.
In order to guarantee realistic fluid dynamic conditions on the airbox inlet section, a part of
the car body was considered too. The airbox simulations were performed by using the
commercial CFD code Fluent v6.3. Since LES results are strongly affected by the numerical
setup used and by the wall-bounded flow condition typical of real flows, a robust LES
methodology was previously defined by the authors on a Backward Facing Step (BFS) test
case and subsequently tested on an IC engine-like intake flow
Design of heat pipes on board accelerating vehicles using the 1D/3D co-simulation approach
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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
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