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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Experiments in fluids 15 (1993), S. 33-41 
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A method for producing oscillatory flow in open-circuit wind tunnels driven by centrifugal fans is described. Performance characteristics of a new device installed on two such tunnels of greatly differing size are presented. It is shown that sinusoidal variations of the working section flow, having peak-to-peak amplitudes up to at least 30% of the mean flow speed and frequencies up to, typically, that corresponding to the acoustic quarter-wave-length frequency determined by the tunnel size, can be obtained with negligible harmonic distortion or acoustic noise difficulties. A brief review of the various methods that have been used previously is included and the advantages and disadvantages of these different techniques are highlighted. The present technique seems to represent a significant improvement over many of them.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Experiments in fluids 7 (1989), S. 119-124 
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Details of a new technique in pulsed wire anemometry, developed to allow measurement of two-point spatial velocity correlations in highly turbulent flows, are described. An outline of the interface devices necessary for linking two anemometers to a microcomputer is given and examples of the use of the technique are presented. Firstly, measurements of spatial correlations with and without time delay in the near wake of a nominally two-dimensional cylinder normal to a uniform stream confirmed the viability of the technique. Secondly, measurements in the highly turbulent, separated region behind a normal flat plate fitted with a downstream splitter plate are presented as a demonstration of the effectiveness of the technique in such ‘difficult’ flows. We believe that these are the first direct measurement of spatial correlation functions within a separated flow.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Experiments in fluids 24 (1998), S. 375-381 
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  combined laser-doppler and cold wire anemometry technique for determining turbulent heat flux is described. The system can be used in flows of arbitrarily high turbulent intensity and large temperature variations. Its potential is demonstrated via measurements in a simulated stable atmospheric boundary layer, for which the Monin-Obukhov length scale was about 70% of the boundary layer depth. Mean and turbulence properties were obtained throughout the boundary layer and the results are shown to be both internally consistent and similar to corresponding field data. Measurements in the highly turbulent, separated flow behind a bluff body mounted in the stable boundary layer are also presented.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Experiments in fluids 8 (1990), S. 343-352 
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A new pulsed wire probe for making velocity and turbulence measurements in the near wall region of incompressible, isothermal boundary layers of all kinds is described. Results of careful calibrations of the probe response in both laminar and turbulent flows are presented, with particular emphasis on the effects of diffusion in the very near wall region. Analytic results for the motion and distortion of a heat puff in linear shear flow near a wall are developed and these are shown to validate a very simple approximate theory that accounts for the diffusional effects. It is demonstrated that correction procedures based on the theory can be successfully implemented. Examples of the use of the probe in highly turbulent, separated flows, as well as more standard boundary layers, are given and its response near the wall is contrasted with that of the corresponding (parallel wire) probe used for surface shear stress measurements.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Flow, turbulence and combustion 51 (1993), S. 173-178 
    ISSN: 1573-1987
    Keywords: separated flow ; turbulence ; end effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Recent measurements show substantial differences in levels of Reynolds stress in otherwise nominally similar separations. No explanation for these differences is know, but it appears they are not associated with end effects. End effects appear to be significant only for unexpectedly small flow width.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Scientometrics 38 (1997), S. 295-308 
    ISSN: 1588-2861
    Source: Springer Online Journal Archives 1860-2000
    Topics: Information Science and Librarianship , Nature of Science, Research, Systems of Higher Education, Museum Science
    Notes: Abstract This work reports on the subject content analysis performed to 1323 records retrieved from international databases, related to the Mexican production on environmental health. The U.S. National Library of Medicine's Medical Subject Headings (MeSH) and BIREME's Health Sciences Descriptors (DeCS) were used as guiding tools to select the subject content of records. Overall, 97 descriptors were identified; 65 corresponded to MeSH terms and 32 were, generated by the authors. Results indicated that most of the production was related to environmental pollution studies focused on water and air pollution, and environmental monitoring. Through the development of hierarchical models, patterns of subjects covered and uncovered could be easily identified. Further lines of action and research are proposed by the authors.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 2 (1982), S. 61-88 
    ISSN: 0271-2091
    Keywords: Vector ; Differencing ; Finite ; lEement ; Scheme ; Recirculating ; Laminar ; Flow ; False ; Diffusion ; Conservation of Energy ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Finite-difference and finite-element techniques have been used to calculate the steady laminar flow over a flat plate normal to an air stream, up to a Reynolds number, Re, based on the plate half-width, of 100. The boundary conditions simulate a central splitter plate downstream of the body, to prevent vortex shedding, so the flow is characterized by a closed recirculation region which grows with increasing Re but at Re = O(100) is very similar in size to the turbulent recirculating region that occurs in the corresponding high Reynolds-number flow. Motivation came, in part, from the increasing efforts of turbulence modellers to calculate complex turbulent flows (containing elliptic regions) and our belief that the numerical methods commonly employed for such work can be inaccurate. The predictions are compared with each other and with some expectations based on classic solutions of the Navier-Stokes equations, and the nature of the numerical errors is demonstrated. It is concluded that effort comparable with that expended in developing turbulence models should be directed to developing higher-order numerical methods, before the numerical accuracy of predictions of, for example, bluff-body flows can be made sufficiently high to sustain detailed discussion of the adequacy of turbulence models in such situations.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 7 (1987), S. 793-823 
    ISSN: 0271-2091
    Keywords: Finite Differencing ; Viscous Flow ; Flow with Recirculation ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: This paper considers the use of various finite differencing schemes for the computation of flows involving regions of recirculation. Standard first-order hybrid schemes, vector (or skew) schemes and second-order schemes are used to predict laminar flows in a channel containing a constriction and over a normal flat plate with a downstream splitter plate. In the former case the results are compared with those of other workers and with the implications of analytic theories for the viscous dominated flow around the sharp corner.Attention is concentrated on the effects of errors arising from the use of non-uniform grids and it is shown that higher-order differencing schemes are generally much less susceptible to these than the simpler schemes. The major conclusion is that for flows containing regions where pressure gradients largely balance the convective terms in the momentum equations, in addition to other regions where convection and diffusion balance, higher order differencing schemes are likely to be essential if accurate predictions are required on grids without excessive numbers of nodes. It is argued that similar conclusions must hold for high Reynolds number turbulent flows.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
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