scholarly journals Determination of mean pressure from PIV in compressible flows using the Reynolds-averaging approach

2018 ◽  
Vol 59 (3) ◽  
Author(s):  
Paul L. van Gent ◽  
Bas W. van Oudheusden ◽  
Ferry F. J. Schrijer
Keyword(s):  
Compressible Flows ◽  
Mean Pressure ◽  
Reynolds Averaging

scholarly journals Quantitative Visualisation of Compressible Flows

2018 ◽  
Vol 2018 (1) ◽  
pp. 137-145
Author(s):  
Wit Stryczniewicz
Keyword(s):  
Transonic Flow ◽  
Compressible Flows ◽  
Flow Visualisation ◽  
Image Velocimetry ◽  
Boundary Layer Interaction ◽  
Field Velocity ◽  
Induced Flow ◽  
Transonic And Supersonic Flows ◽  
Quantitative Flow

Abstract The paper demonstrates the feasibility of quantitative flow visualisation methods for investigation of transonic and supersonic flows. Two methods and their application for retrieving compressible flow field properties has been described: Background Oriented Schlieren (BOS) and Particle Image Velocimetry (PIV). Recently introduced BOS technique extends the capabilities of classical Schlieren technique by use of digital image processing and allow to measure density gradients field. In the presented paper a review of applications of BOS technique has been presented. The PIV is well established technique for whole field velocity measurements. This paper presents application of PIV for determination of the shock wave position above airfoil in transonic flow regime. The study showed that application of quantitative flow visualisation techniques allows to gain new insights on the complex phenomenon of supersonic and transonic flow over airfoils like shock-boundary layer interaction and shock induced flow separation.

scholarly journals The intradiscal failure pressure on porcine lumbar intervertebral discs: an experimental approach

2015 ◽  
Vol 6 (2) ◽  
pp. 255-263 ◽  
Author(s):  
A. R. G. Araújo ◽  
N. Peixinho ◽  
A. Pinho ◽  
J. C. P. Claro
Keyword(s):  
Hydrostatic Pressure ◽  
Intervertebral Disc ◽  
Complex Loading ◽  
Hydraulic Cylinder ◽  
Intervertebral Discs ◽  
Failure Pressure ◽  
Mean Pressure ◽  
Disc Injury ◽  
Pressure Failure

Abstract. The intervertebral disc is submitted to complex loading during its normal daily activities which are responsible for variations of the hydrostatic pressure in its structure. Thus, the determination of the magnitude of failure hydrostatic pressure is essential as a potential for the evaluation of the mechanisms that promote the weakening and the disruption of the annular fibers, commonly linked to herniation process on the spine column. However, few studies include the determination of the failure pressure on discs and the results are widely contradictory. Therefore, the objective of the present work is to determine the values of IDP that promotes the disc disruption. To achieve this goal, the tests were performed using a hydraulic cylinder that inflates the intervertebral disc. The results revealed a mean pressure failure of 0.62 ± 0.08 MPa for lumbar porcine samples (n = 6). From this approach it can be concluded that (1) the potential for disc injury may exist at low pressures for lumbar porcine discs when compared several animal and human ones; (2) the rupture of human cervical and porcine lumbar annular fibers could occur for values of intradiscal pressure that are within the physiological range.

An illustration of the experimental range of variation of blood pressure

1984 ◽  
Vol 246 (4) ◽  
pp. R516-R532 ◽  
Author(s):  
A. S. Iberall
Keyword(s):  
Blood Pressure ◽  
Longitudinal Data ◽  
Frequency Domain ◽  
Time Scales ◽  
Mammalian Species ◽  
Office Visits ◽  
Mean Pressure ◽  
Range Of Variation

The nominal uniformity of long-term mean pressure (approximately 100 mmHg at heart level) for all mammalian species belies the broad nature of its variance, which is found at many time scales. Such variations should be a useful index of physiologically normal and pathological processes. However, it is dubious whether a scientifically meaningful determination of central blood pressure at its many process scales can be achieved from a few isolated measurements: to cite a common and highly significant instance, measurement made by a physician on a patient during one or two office visits. The data presented here are far from exhaustive (a few reports in the literature and detailed longitudinal data on 1 subj), but they serve to illustrate a protocol and a sample of the physiological results that might be expected if data were gathered for larger populations. The basic scales of interest lie in the lower-frequency domain, involving periods of fluctuations longer than tens of minutes.

scholarly journals Estimation of Seams in Paraglider Wing

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Paulina Maślanka ◽  
Ryszard Korycki ◽  
Halina Szafrańska
Keyword(s):  
Pressure Difference ◽  
Relative Elongation ◽  
Test Results ◽  
Physical Strength ◽  
Covering Material ◽  
Mean Pressure ◽  
Maximal Pressure ◽  
Flight Parameters ◽  
The Mean

AbstractThe aim of the article is to analyze the seams connecting the covering textiles in paraglider wing and estimate their physical strength. The most extreme flight parameters (the angle of attack and velocity) in the numerical model of the wing allow the determination of the mean pressure inside the contour and the maximal difference between the pressures on the inner and the outer material surfaces. The preprocessing stage and numerical calculations in Ansys environment consider three different covering materials. The tool Porous Media is used to create the objects of a given value of air permeability. The estimated parameter of seam is the maximal pressure difference between both sides of the covering material, which that interacts with the test results. The quality index of the seam is defined by the maximal force to seam rupture and relative elongation during rupture. The obtained results indicate that the seams are resistant to the pressure difference caused by the most extreme flight parameters.

Galactic orbits of stars

1966 ◽  
Vol 25 ◽  
pp. 93-97
Author(s):  
Richard Woolley
Keyword(s):  
Globular Cluster ◽  
Potential Field ◽  
High Velocity ◽  
Velocity Vector ◽  
Variable Stars ◽  
The Sun ◽  
Proper Motions ◽  
Rr Lyrae ◽  
The Galaxy

It is now possible to determine proper motions of high-velocity objects in such a way as to obtain with some accuracy the velocity vector relevant to the Sun. If a potential field of the Galaxy is assumed, one can compute an actual orbit. A determination of the velocity of the globular clusterωCentauri has recently been completed at Greenwich, and it is found that the orbit is strongly retrograde in the Galaxy. Similar calculations may be made, though with less certainty, in the case of RR Lyrae variable stars.

Distance to SN 1987A and the LMC

1999 ◽  
Vol 190 ◽  
pp. 549-554
Author(s):  
Nino Panagia
Keyword(s):  
Angular Size ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Light Curves ◽  
Distance Modulus ◽  
Absolute Size ◽  
Sn 1987A

Using the new reductions of the IUE light curves by Sonneborn et al. (1997) and an extensive set of HST images of SN 1987A we have repeated and improved Panagia et al. (1991) analysis to obtain a better determination of the distance to the supernova. In this way we have derived an absolute size of the ringRabs= (6.23 ± 0.08) x 1017cm and an angular sizeR″ = 808 ± 17 mas, which give a distance to the supernovad(SN1987A) = 51.4 ± 1.2 kpc and a distance modulusm–M(SN1987A) = 18.55 ± 0.05. Allowing for a displacement of SN 1987A position relative to the LMC center, the distance to the barycenter of the Large Magellanic Cloud is also estimated to bed(LMC) = 52.0±1.3 kpc, which corresponds to a distance modulus ofm–M(LMC) = 18.58±0.05.

International determination of the total motion of the pole

1961 ◽  
Vol 13 ◽  
pp. 29-41
Author(s):  
Wm. Markowitz
Keyword(s):  
Secular Motion ◽  
The Future

A symposium on the future of the International Latitude Service (I. L. S.) is to be held in Helsinki in July 1960. My report for the symposium consists of two parts. Part I, denoded (Mk I) was published [1] earlier in 1960 under the title “Latitude and Longitude, and the Secular Motion of the Pole”. Part II is the present paper, denoded (Mk II).

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