Avalanching flow of cohesive powders

Alexander, Albert; Chaudhuri, Bodhisattwa; Faqih, AbdulMobeen; Muzzio, Fernando J.; Davies, Clive E; Tomassone, M. Silvina

doi:10.1016/j.powtec.2006.01.017

Cited by 118 publications

(58 citation statements)

References 32 publications

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“…The results show a periodic motion in the free-flowing LH100, as expected from the study by Alexander et al [2], with a turnover time of approximately 5 seconds. However, there is no clear periodic behaviour in the other samples.…”

Section: Resultssupporting

confidence: 87%

“…However, there is no clear periodic behaviour in the other samples. Figure 9 shows the coupling between the X and Y coordinates, consistent with previous studies as a slumping motion [2,5]. Comparing the X and Y deviations in mm around the average value for LH100 at a rotation speed of 20 revolutions per minute (0.33Hz).…”

Section: Resultssupporting

confidence: 86%

“…The experiment was repeated with LH100 at the increased drum rotation speeds of 36 revolutions per minute (0.66Hz) and 66 revolutions per minute (1.1Hz) to see whether this coupled behaviour would persist, or, as anticipated by previous studies [2], reduce significantly. Figure 10 shows the comparison between the X and Y coordinates for LH100 at 0.33Hz, 0.66Hz and 1.1 Hz.…”

Section: Resultsmentioning

confidence: 92%

“…Clearly the use of avalanche testers is not new, and a thorough study of both free-flowing and cohesive powder behaviour in testers of this nature has been done by Alexander et al [2], including the use of variants of lactose. However, the tester used had a diameter of 140mm and a length of 420mm, compared to a diameter of 20mm and length 35mm in this study.…”

Section: Introductionmentioning

confidence: 99%

“…However, the tester used had a diameter of 140mm and a length of 420mm, compared to a diameter of 20mm and length 35mm in this study. Alexander et al [2] demonstrated that free-flowing materials in avalanche showed a periodic behaviour at low agitation with a smoother, more continuous behaviour at high rotational speeds. Particles that were "drycohesive", where interparticle liquid bridges were not the main source of cohesion, showed more hysteresis and localised responses to agitation that did not show the periodic motion displayed by the free-flowing material.…”

Section: Introductionmentioning

confidence: 99%

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Measuring the flow properties of small powder samples using an avalanche tester

2015

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Citation: JAGGI, V., LEAPER, M. and INGHAM, A., 2016. Measuring the flow properties of small powder samples using an avalanche tester. Drying Technology, 34 (6), pp.723-728. Abstract -The feasibility of using a small-scale avalanche tester to measure the flow properties of pharmaceutical lactose powders was examined. The modes of behaviour observed in larger systems were displayed and showed a clear distinction between angular, free-flowing particles and more spherical particles of similar flow characteristics. Angular Lactohale LH100 particles showed slumping behaviour at a rotational frequency of 0.33Hz which disappeared at higher frequencies. Spherical lactose powder with a similar flow function to LH100 only showed rolling behaviour under the same conditions, as did more cohesive powders LH200 and LH300. Further investigation of the LH100 data using Fast Fourier analysis showed that the slumping frequency was 1/10 th of the rotational frequency.

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Section: Resultssupporting

confidence: 87%

Section: Resultssupporting

confidence: 86%

Section: Resultsmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Measuring the flow properties of small powder samples using an avalanche tester

2015

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Granulation of snow: From tumbler experiments to discrete element simulations

Steinkogler

Gaume²,

Löwe³

et al. 2015

J. Geophys. Res. Earth Surf.

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It is well known that snow avalanches exhibit granulation phenomena, i.e., the formation of large and apparently stable snow granules during the flow. The size distribution of the granules has an influence on flow behavior which, in turn, affects runout distances and avalanche velocities. The underlying mechanisms of granule formation are notoriously difficult to investigate within large-scale field experiments, due to limitations in the scope for measuring temperatures, velocities, and size distributions. To address this issue we present experiments with a concrete tumbler, which provide an appropriate means to investigate granule formation of snow. In a set of experiments at constant rotation velocity with varying temperatures and water content, we demonstrate that temperature has a major impact on the formation of granules. The experiments showed that granules only formed when the snow temperature exceeded −1 ∘ C. No evolution in the granule size was observed at colder temperatures. Depending on the conditions, different granulation regimes are obtained, which are qualitatively classified according to their persistence and size distribution. The potential of granulation of snow in a tumbler is further demonstrated by showing that generic features of the experiments can be reproduced by cohesive discrete element simulations. The proposed discrete element model mimics the competition between cohesive forces, which promote aggregation, and impact forces, which induce fragmentation, and supports the interpretation of the granule regime classification obtained from the tumbler experiments. Generalizations, implications for flow dynamics, and experimental and model limitations as well as suggestions for future work are discussed.

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Rising Like a Phoenix from the Ashes: Fire‐Proof Magnetically Retrievable Supraparticles with an Optical Fingerprint for Postmortem Identification of Products

Miller

Wenderoth

Wintzheimer

et al. 2022

Advanced Optical Materials

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correctly and rarely meet the required safety standards. [1,2] Frequently, counterfeit components cause a short circuit, overheat, and subsequently catch fire. Manufacturers are liable in such a scenario and face an enormous reputational loss unless they can prove forgery. This topic is highly relevant for forward-looking industries such as electromobility and automatization, since counterfeit battery cells, for example, can result in vehicle fires.Fire-proof postmortem labels could, for example, enable publicly appointed and sworn experts to verify the originality of a product even after a fire. To our knowledge, however, there are currently no suitable marking technologies available to prove beyond doubt the originality of an object after a fire.In forensic science, comprehensive analytical methods have been applied and further developed to characterize fire debris. Examples include gas chromatography coupled with a mass spectrometry detector, [3][4][5] isotopic ratio mass spectrometry, [6,7] capillary electrophoresis, [8][9][10] or vibrational spectroscopic analysis methods, such as Raman or infrared spectroscopy. [11][12][13] All established methods for the characterization of fire residues have in common that they are complicated, as well as time-and cost-intensive, since also partly complex extraction steps of the analyte are necessary. Moreover, they are based exclusively on the analysis of the intrinsic material properties of burned objects, which, however, can change considerably and manifold depending on the fire condition. [14] Conventional anticounterfeiting features, such as miniaturized printed watermarks or quick response (QR) codes, as well as radio-frequency Identification (RFID) chips, show a sufficient performance during the useful life of a product but are unsuitable for postmortem identification as they are to a large extent not fire-proof. There have been attempts to coat RFID chips with anti-fire materials to increase their resistance when exposed to fire. However, tests were successful only up to 250 °C and the tags are limited in that their components decompose thermally above temperatures beyond ≈500 °C. [15] In addition, these tags are in the macroscopic size range and are not suitable for marking components of electronic devices (e.g., microchips).For these reasons, novel approaches are needed to verify the originality of burned electronic devices. Within the last Counterfeit electronic products not only cause financial losses but also come with safety risks. The worst-case failure scenario certainly is a fire event. Since manufacturers are liable for damages and suffer image loss, fire-proof postmortem taggants are needed, enabling differentiation between originals and counterfeits even after a fire incident. This work presents such taggants: optomagnetic supraparticles (SPs), i.e., complex microscale particles composed of luminescent and magnetic nanoparticles (NPs) are generated. Their hybrid nature is pivotal, as magnetic separation can effectively remove the tags from light-absorb...

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Avalanching flow of cohesive powders

Cited by 118 publications

References 32 publications

Measuring the flow properties of small powder samples using an avalanche tester

Measuring the flow properties of small powder samples using an avalanche tester

Granulation of snow: From tumbler experiments to discrete element simulations

Rising Like a Phoenix from the Ashes: Fire‐Proof Magnetically Retrievable Supraparticles with an Optical Fingerprint for Postmortem Identification of Products

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