Pulsed field-gradient spin echo N.M.R. studies of flow in fluids

Hayward, Rhodri; Packer, Kenneth J.; Tomlinson, David

doi:10.1080/00268977200101061

Cited by 69 publications

(27 citation statements)

References 24 publications

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“…1 In 1996, Lebon et al 2 used PGSE NMR methods to measure the displacements of molecules in the stochastic flow as fluid was forced through a random porous medium, and in 1997, Seymour and Callaghan 3 carried out an extensive PGSE NMR investigation of time scale dependence of dispersion. These authors made comparisons, with literature data from other methods, of Peclet number dependence of nondimensionalized, asymptotic dispersion coefficients, measured transverse, and longitudinal to the flow direction, while subsequent studies by other groups [4][5][6] extended this work.…”

Section: Introductionmentioning

confidence: 99%

Nuclear magnetic resonance measurement and lattice-Boltzmann simulation of the nonlocal dispersion tensor

2010

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The nonlocal dispersion tensor D NL provides a fundamental description of velocity correlations and displacement information in a dispersive system. It is shown that pulsed gradient spin echo nuclear magnetic resonance can be used to measure this tensor, and we present here the first measurement of D NL in a complex flow by this or any other methods. These measurements are complemented by simulations based on a lattice-Boltzmann calculation of the fluid flow. For dispersive flow in a random bead pack of monosized spheres, six nonzero, independent components remain. These components have been measured at three times less than v , the time to flow one bead diameter. It is shown here that the various elements of D NL provide insights regarding the dispersive flow, which are extremely sensitive to the details of local correlations.

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Section: Introductionmentioning

confidence: 99%

Nuclear magnetic resonance measurement and lattice-Boltzmann simulation of the nonlocal dispersion tensor

2010

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“…This phenomenon, which does not infer structural information, 6 but rather, details of the flow field, has recently been termed "displacement diffraction" [24]. This effect was first observed in liquid laminar flow 30 years ago by Hayward et al [28], and has also been seen in samples suffering convection [29]. The first minimum occurs at the reciprocal of the maximum spin displacement during the flow encode time, allowing an estimation of the maximum velocity being experienced in the flow field.…”

Section: Resultsmentioning

confidence: 99%

Applications of controlled-flow laser-polarized xenon gas to porous and granular media study

Mair

Wang

Rosen

et al. 2003

Magnetic Resonance Imaging

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We report initial NMR studies of continuous flow laser-polarized xenon gas, both in unrestricted tubing, and in a model porous media. The study uses Pulsed Gradient Spin Echo-based techniques in the gas-phase, with the aim of obtaining more sophisticated information than just translational selfdiffusion coefficients. Pulsed Gradient Echo studies of continuous flow laser-polarized xenon gas in unrestricted tubing indicate clear diffraction minima resulting from a wide distribution of velocities in the flow field. The maximum velocity experienced in the flow can be calculated from this minimum, and is seen to agree with the information from the complete velocity spectrum, or motion propagator, as well as previously published images. The susceptibility of gas flows to parameters such as gas mixture content, and hence viscosity, are observed in experiments aimed at identifying clear structural features from echo attenuation plots of gas flow in porous media. Gas-phase NMR scattering, or position correlation flow-diffraction, previously clearly seen in the echo attenuation data from laserpolarized xenon flowing through a 2 mm glass bead pack is not so clear in experiments using a different gas mixture. A propagator analysis shows most gas in the sample remains close to static, while a small portion moves through a presumably near-unimpeded path at high velocities.

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“…Nous allons maintenant examiner une autre possibilité d 'exploiter la relation (8). Notons Mo(t) et MI (t, k ), les valeurs moyennes dans le temps de Mo (t ) et MI (t, k), deux valeurs accessibles par RMN.…”

Section: Boucle Diphasiqueunclassified

“…Notons Mo(t) et MI (t, k ), les valeurs moyennes dans le temps de Mo (t ) et MI (t, k), deux valeurs accessibles par RMN. En combinant les équations (8) et (9), on obtient:…”

Section: Boucle Diphasiqueunclassified

“…L'analyse des écoulements de fluide grâce à des techniques d'écho de spins a eu un développe-ment plus lent. Les premières études ont essentiellement porté sur des écoulements lents en canal [3, [6][7][8][9]. Toutefois, dès 1969, de GENNES [10] établissait que le temps de corrélation des vitesses pouvait être relié à l'atténuation des échos pairs dans une séquence de CARR-PURCELL [II].…”

Section: Introductionunclassified

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