1,721,162 research outputs found
Doolan, C F, SX9917
No full textThis record was harvested from a previous catalogue system and will be withdrawn in 2025. Information in this record may be superseded or incomplete. Visit this record in UMA's new catalogue at: https://archives.library.unimelb.edu.au/nodes/view/382270Surname: DOOLAN. Given Name(s) or Initials: C F. Military Service Number or Last Known Location: SX9917. Missing, Wounded and Prisoner of War Enquiry Card Index Number: 30914.213323
Item: [2016.0049.14563] "Doolan, C F, SX9917
Tandem cylinder flow and noise predictions using a hybrid RANS/LES approach
Full text linkThe performance of a novel hybrid RANS/LES methodology for accurate flow and noise predictions of the NASA Tandem Cylinder Experiment is investigated. The proposed approach, the modified Flow Simulation Methodology (FSM), is based on scaling the turbulence viscosity and the turbulence kinetic energy dissipation rate with a damping function. This damping function consists of three individual components, a function based on the Kolmogorov length-scale ensuring correct behaviour in the direct numerical simulation (DNS) limit, a function ensuring that FSM provides the correct damping in large-eddy simulation (LES) mode, and a shielding function that forces the switch from Reynolds-Averaged Navier–Stokes (RANS) to LES to occur outside the boundary layer. The FSM is proposed for the kω-SST two-equation model (FSM-SST) and for an Explicit-Algebraic-Stress-Model (FSM-EASM), which is better suited to resolve anisotropy and non-equilibrium of the unresolved scales and the strain and rotation-rate dependent coefficients introduce a dynamic response of the model to the resolved flow field. Simulations are performed on a relatively coarse grid and the FSM data are compared with results obtained from the Scale-Adaptive-Simulation (SAS) and IDDES approaches. Acoustic predictions are obtained using an acoustic analogy approach based on Curle’s theory. The FSM-SST approach was found to predict the hydrodynamic field in very good agreement with reference data, whereas the FSM-EASM did not improve the predictions. The acoustic spectra predicted show good agreement with experimental results at various microphone positions, with some deficiencies in capturing the broadband noise levels at high Strouhal numbers
AN EXPERIMENTAL INVESTIGATION OF TURBULENT BOUNDARY- LAYER INTERACTION WITH DIFFERENT SERRATED TRAILING-EDGE CONFIGURATIONS
Full text linkThe paper presents an experimental investigation of a turbulent boundary-layer interaction over a single large triangular serration at the Trailing-Edge (TE) of an airfoil on the flow-induced noise. Experiments were conducted at low-to-moderate Reynolds number given by 1.8 105 < Rec < 5.7 105, where c is the chord of airfoil. Six different TE serration geometries were studied: Three serrations with a single large triangular geometry at the TE, two serrations with varying orientation relative to the airfoil, and a straight-edged reference plate (in which the TE triangular serration is not considered). The airfoils with different TE configurations were placed in an anechoic wind tunnel in a
mean flow field with free-stream velocities of 25, 30 and 35 ms1. The radiated acoustic pressure field was recorded using a spiral microphone array located in the far-field. It was found that a significant noise reduction up to 6 dB was obtained when the included angle of the triangular serration was less
than 45,which was in agreement with Howe’s theory. The Conventional Beamforming (CB) source maps confirmed that the noise reduction was obtained by varying the included angle of the triangular serrations. It was observed that the maximum noise attenuation occurred at frequencies above 5 kHz, where the TE noise dominates over the Leading-Edge (LE) noise. For frequencies below 5 kHz, the LE noise sources dominate over the TE noise
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
Statistical estimation of turbulent trailing edge noise
No full textThe efficient computation of turbulent airfoil trailing edge noise is important for the cost-effective design of fixed and rotary-wing aircraft, wind turbines, fans and submarines. Recently, the computation of trailing edge noise has mainly been attempted using either direct or hybrid methods of computational aeroacoustics (CAA). However, many of these approaches rely on expensive transient flow solution methods for acoustic source term calculation, such as direct numerical simulation (DNS) or large eddy simulation (LES), which aren't appropriate for engineering design purposes. This paper will present a new approach for calculating turbulent trailing edge noise. Instead of using DNS or LES for a flow solution, the method uses mean flow solutions (Reynolds Averaged Navier Stokes or RANS) and a statistical model to calculate acoustic source terms and radiated far-field noise. After the method is presented, results showing the noise generated by the passage of turbulent flow past a sharp edged flat plate will be shown. For the purposes of validation, the model will use mean flow data from both DNS and RANS solutions to calculate the acoustic source terms. Simulated noise will then be compared with an empirical model of flat-plate trailing edge noise. The paper will conclude with remarks on the accuracy of the method and a discussion of future test cases required to test its validity in more challenging flow conditions.C. J. Doolan, C. Albarracin Gonzalez and C. H. Hanse
- …
