Non-invasive measurements of granular flows by magnetic resonance imaging

Nakagawa, Masami; Altobelli, Stephen A.; Caprihan, Arvind; Fukushima, Eiichi; Jeong, EunHa

doi:10.1007/bf00188507

Cited by 287 publications

(106 citation statements)

References 11 publications

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“…There are several common methods used to characterize grain ensembles, irrespective of grain shapes. Modern experimental tools like X-ray Computed Tomography (X-ray CT) or Magnetic Resonance Imaging (MRI) are increasingly used for characterizing not only coarse grain packing [24][25][26], but also local packing structures and orientation at the grain level [27][28][29]. Grain sizes accessible with X-ray CT equipment range from several micrometers [30] to centimeters [28].…”

Section: B Characterization Methods and Modelingmentioning

confidence: 99%

“…MRI, on the other hand, requires the presence of liquids containing NMR sensitive nuclei, the most abundant ones being protons. In order to employ this method for the analysis of granular beds, one is either restricted to NMR sensitive grains like seeds [24] or pharmaceutic pills, or one has to study solid particles immersed in a liquid [26]. One can mark and trace particles with appropriate radio frequency and magnetic field gradient pulse sequences [31].…”

Section: B Characterization Methods and Modelingmentioning

confidence: 99%

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Granular materials composed of shape-anisotropic grains

2013

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Granulate physics has made considerable progress during the past decades in the understanding of static and dynamic properties of large ensembles of interacting macroscopic particles, including the modeling of phenomena like jamming, segregation and pattern formation, the development of related industrial applications or traffic flow control. The specific properties of systems composed of shape-anisotropic (elongated or flattened) particles have attracted increasing interest in recent years. Orientational order and self-organization are among the characteristic phenomena that add to the special features of granular matter of spherical or irregular particles. An overview of this research field is given.Final version published in Soft Matter,

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Section: B Characterization Methods and Modelingmentioning

confidence: 99%

Section: B Characterization Methods and Modelingmentioning

confidence: 99%

Granular materials composed of shape-anisotropic grains

2013

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“…Indeed, when L increases, the second term in Eq. (6) vanishes and the free surface should tend toward a flat plane. This is demonstrated by Fig.…”

Section: Figmentioning

confidence: 99%

“…Depending on the angular velocities, two different regimes occur. At low rotation speed the free surface of the pile is inclined and flat, but a significant curvature appears at high rotation speed: the so called S shape [4,5,6]. Up until now this transition remains relatively unexplored [1,7].…”

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confidence: 99%

Sshape of a granular pile in a rotating drum

2006

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The shape of a granular pile in a rotating drum is investigated. Using Discrete Elements Method (DEM) simulations we show that the "S shape" obtained for high rotation speed can be accounted for by the friction on the end plates. A theoretical model which accounts for the effect of the end plates is presented and the equation of the shape of the free surface is derived. The model reveals a dimensionless number which quantifies the influence of the end plates on the shape of the pile. Finally, the scaling laws of the system are discussed and numerical results support our conclusions.

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“…Three-dimensional granular systems have been studied experimentally by external probes such as capacitance [28], mutual inductance [29] and diffusingwave spectroscopy [30], as well as by non-invasive internal probes including NMR [31,32,33,34,35,36] and positron-emission particle tracking (PEPT) [37]. The PEPT method has been used to measure the granular temperature profile of a vibrofluidized bed at volume filling fractions up to 0.15 [37].…”

Section: Introductionmentioning

confidence: 99%

NMR experiments on a three-dimensional vibrofluidized granular medium

et al. 2004

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A three-dimensional granular system fluidized by vertical container vibrations was studied using pulsed field gradient (PFG) NMR coupled with one-dimensional magnetic resonance imaging (MRI). The system consisted of mustard seeds vibrated vertically at 50 Hz, and the number of layers N ℓ ≤ 4 was sufficiently low to achieve a nearly time-independent granular fluid. Using NMR, the vertical profiles of density and granular temperature were directly measured, along with the distributions of vertical and horizontal grain velocities. The velocity distributions showed modest deviations from Maxwell-Boltzmann statistics, except for the vertical velocity distribution near the sample bottom which was highly skewed and non-Gaussian. Data taken for three values of N ℓ and two dimensionless accelerations Γ = 15, 18 were fit to a hydrodynamic theory, which successfully models the density and temperature profiles including a temperature inversion near the free upper surface.

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Non-invasive measurements of granular flows by magnetic resonance imaging

Abstract: • ._, DOE/PC/90184--T9

Cited by 287 publications

References 11 publications

Granular materials composed of shape-anisotropic grains

Granular materials composed of shape-anisotropic grains

Sshape of a granular pile in a rotating drum

NMR experiments on a three-dimensional vibrofluidized granular medium

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