Positron Emission Particle Tracking of Granular Flows

Abstract

Positron emission particle tracking (PEPT) is a noninvasive technique capable of imaging the three-dimensional dynamics of a wide variety of powders, particles, grains, and/or fluids. The PEPT technique can track the motion of particles with high temporal and spatial resolution and can be used to study various phenomena in systems spanning a broad range of scales, geometries, and physical states. We provide an introduction to the PEPT technique, an overview of its fundamental principles and operation, and a brief review of its application to a diverse range of scientific and industrial systems.

Positron Emission Particle Tracking for Liquid‐Solid Mixing in Stirred Tanks

“…If, as is the case in the present work, a system exists in a dynamic steady state and can be considered ergodic, i.e., a time average is equivalent to an ensemble average, the packing fraction of particles, i.e., their solids fraction, can be measured indirectly using the occupancy values acquired [47,63]. To put it more simply, for such a system it is safe to assume that if over a suitably long measurement period a given particle within said system spends 1 % of its time in a given subvolume or 'voxel', then at any given point in time one may expect, on average, 1 % of all the particles in the system to be found in this voxel.…”

“…It is important to note that the above represents a significantly abridged and simplified explanation of the PEPT technique. Further details relating to PEPT and its application to chemical engineering systems can be found in a recent review [47] and references therein.…”

“…With PEPT, a pseudo-continuous measurement may be obtained with arbitrarily fine resolution, limited only by the amount of data available [47]. The former issue is in fact addressed in the 2014 work of Carletti et al [69], who consider the overall mean conductivity, as opposed to that specific to a given slice.…”

“…(6) may be used on the resultant data to obtain a value for the ''overall'' homogeneity of the solids distribution. Finally, in addition to looking simply at the homogeneity of the particle distributions in absolute terms, one may also look at segregation between the different particle species using methodologies described in detail in [47,66,71].…”

Liquid Metal Flow Studied by Positron Emission Tracking

“…More details of the PEPT technique and its uses can be found elsewhere. [10][11][12][13][14][15][16] The PEPT experiments have been compared with CFD simulations [17,18] and other commonly used visualization techniques, such as Particle Image Velocimetry (PIV) [19] with good agreement being obtained. Previous studies carried out on the application of this technique for opaque liquid, which included tracking of radioactive particles in steel castings, [20] and Al alloy sand castings [21] showed promising results to observe liquid metal flow and locate tracked particles in cast metals.…”