Article
Geochemistry & Geophysics
Elbasher Mohamed Elbasher Ahmed, Indresan Govender, Aubrey Njema Mainza
Summary: Experiments and simulations show that polydisperse granular mixtures in rotating drums exhibit axial segregation, forming (alternating) bands which coarsen over time due to logarithmic merging. Current models mainly focus on bidisperse mixtures and struggle to reproduce band coarsening, with one suggesting that grains diffuse into axial bands due to concentration fluctuations caused by limited mobility. Generalizing this model to multi-species mixtures reveals more complex banding evolution compared to binary mixtures, including sinusoidal-like variations that evolve nonlinearly in time. Interestingly, the study successfully recovers band coarsening over time, a phenomenon that is generally difficult to reproduce, even experimentally. Contrary to previous findings, configurations in this study did not produce nested bands for ternary and quaternary mixtures.
Article
Engineering, Chemical
Siyuan He, Yuelei Wang, Zongyan Zhou, Jieqing Gan, Aibing Yu, David Pinson
Summary: Granular materials of different sizes and shapes tend to segregate in the axial direction in a rotating drum. Previous studies have mainly focused on spherical particles, while the segregation of non-spherical particles has received limited attention. In this study, we found that ellipsoidal particles with aspect ratio varying from 0.5 to 2.0 can form bands. The results demonstrate that ellipsoids have lower flowability, which reduces the tendency of band formation. Additionally, small particles in the bands come from different regions depending on the particle shape, and the radial size-induced segregation pattern develops quickly.
Article
Engineering, Chemical
S. Y. He, J. Q. Gan, D. Pinson, A. B. Yu, Z. Y. Zhou
Summary: The study reveals that in rotating drums, spheres in ellipsoid-sphere mixtures tend to segregate axially to the middle section, with lower segregation degree as the aspect ratio increases. The axial flow induced by frictional end walls and radial segregation are essential for the development of particle shape-induced axial segregation.
CHEMICAL ENGINEERING SCIENCE
(2021)
Article
Engineering, Chemical
Zhijian Zuo, Jiajie Wang, Xintao Chen, Shuguang Gong, Haishan Lu
Summary: This study explores a novel horizontal split drum design to drive axial segregation of granular matter by two reverse rotating sub-drums. It was found that true axial segregation occurs in the split drum with heavier particles accumulating near the split. Increasing the drum speed accelerates the segregation process but has no significant influence on the final particle distribution. These findings have important implications for the design of particle processing industries.
ADVANCED POWDER TECHNOLOGY
(2022)
Article
Engineering, Chemical
Wenzheng Xiu, Ra Li, Quan Chen, Qicheng Sun, Vladimir Zivkovic, Hui Yang
Summary: This paper investigates particle sorting in a binary granular system composed of particles with different sizes and the same density. The segregation pattern is mainly influenced by the granular velocity and concentration in the flow layer. Experimental measurements of velocity and concentration were conducted in a quasi-two-dimensional rotating drum to establish the relationship between granular velocity and concentration, and to analyze the corresponding relationships with the segregation pattern. This research aims to improve theoretical models of segregation and provide guidance for granular segregation control in production processes.
Article
Mechanics
P. Brockmann, M. Tvarozek, M. Lausch, J. Hussong
Summary: In this study, previously unreported particle patterns are observed in completely filled rotating drum flows and completely filled co-rotating Taylor-Couette flows for suspensions of initially uniform dispersed non-Brownian particles under the influence of gravity. The experiments include thorough phase mapping for both drum flow and Taylor-Couette flow, and a total of 55 different geometrical combinations are considered. The results show that the pattern formation in drum flow is strongly dependent on the outer cylinder diameter, while in Taylor-Couette flow, the gap height has a strong effect on the pattern formation. Additionally, the wavelength of all band patterns in Taylor-Couette flow is found to be dependent on the cylinder radius and system curvature.
Article
Engineering, Chemical
Mohammed Istafaul Haque Ansari, Ashish Bhateja, Ishan Sharma
Summary: We investigate axial segregation of binary mixtures in a laterally shaken horizontal channel formed by ratchet-like sidewalls. The segregation process is influenced by parameters such as grain size ratio, shaking frequency, and channel geometry. The quality of segregation depends on shaking frequency, with an optimal frequency for segregation. The segregation quality correlates with the interfacial pressure gradient.
Article
Engineering, Chemical
Hongyu Chen, Milind A. Jog, Douglas E. Evans, Leonid A. Turkevich
Summary: Dustiness evaluation is crucial in estimating potential exposure to toxic, hazardous, or irritant powders. The Rotating Drum is a widely used instrument for assessing powder dustiness, but its aerodynamics during operation is not fully understood. Utilizing computational fluid dynamics to study the flow inside the Rotating Drum can aid in interpreting dustiness measurements and guiding manufacturing processes to generate less dust.
Article
Engineering, Chemical
A. N. Huang, X. Wang, W. Y. Hsu, H. P. Kuo
Summary: By studying the effects of the position and size of inner segmentation rings on axial and radial segregation patterns in a rotating drum, it was found that the rings located outside the shear zone independently affect local mixing. The drum mixing index monotonically increases with ring width, and a specific ring width can cause a long-term segregation pattern change.
Article
Engineering, Chemical
A. N. Huang, T. H. Cheng, W. Y. Hsu, C. C. Huang, H. P. Kuo
Summary: DEM simulations were used to study size segregation of binary mixture in a rotating drum with inner diameter variations. The results showed that larger particle enrichment occurs in the smaller inner diameter regions. The effect of inner diameter contracting ratio (CR) on particle dynamics was further investigated, with CR of 0.9 leading to smaller particles moving towards dilated larger inner diameter regions.
Article
Engineering, Chemical
W. Z. Xiu, R. Li, Q. Chen, Q. C. Sun, V. Zivkovic, H. Yang
Summary: In binary-size granular segregation models, the relationship between control parameters and kinetic parameters was studied using machine vision and particle image velocimetry. It was found that the configuration of segregation pattern changes with control parameters, with the ratio of segregation effects to diffusion effects decreasing approximately linearly as the volume flow rate decreases. These experimental results help reveal the mechanism of segregation and provide reference data for improving theoretical models.
Article
Mechanics
Veronika Dyakova, Denis Polezhaev
Summary: The stability of the interface between a low-viscosity fluid and a granular medium in a horizontally rotating cylinder is experimentally investigated. Two cases are considered, namely, plastic particles in a more dense fluid and plastic particles in a less dense fluid. The stability threshold and size of regular ripples are studied in relation to rotation rate, relative density of the two media, and volume of granular material. The observed instability is similar to the Kelvin-Helmholtz instability observed in classical fluids, but with potential differences due to the specific characteristics of granular rheology.
Article
Mechanics
Jannike Solsvik, Eirik Manger
Summary: The kinetic theory for granular mixtures considers a separate granular temperature for each solid phase, with particle phases assumed to follow a Maxwellian distribution and a zero-order approximation of the Boltzmann equation. A solution strategy is presented for solving the integrals of the collisional closure relations, allowing for the consideration of solid particle hydrodynamic velocities in the distribution function. However, the strategy limits the validity of the closure relations to relatively small and moderate hydrodynamic velocity differences, which can significantly differ from simplified models traditionally neglecting such differences.
Article
Engineering, Chemical
Sunil Kumar, Salma Khatoon, Jeetram Yogi, Sanjay Kumar Verma, Anshu Anand
Summary: The current investigation focuses on studying the impact of particle shape on the segregation of a bi-disperse mixture of particles in a rotating drum. Various particle parameters such as shape, size, density, and size ratio, as well as system parameters like time and rotational speed, are examined. The results indicate that both the shape of coarse and fine particles influence the mixing process. The choice of particle shape can be used to control segregation in different industrial scenarios.
Article
Mechanics
Mingrui Dong, Zhongzheng Wang, Benjy Marks, Yu Chen, Yixiang Gan
Summary: This study investigates partially saturated granular flows in rotating drums through experiments and simulations. It explores the effects of cohesion and rotation rate on the flow patterns and flow depth. Additionally, the study reveals that stronger cohesion promotes the formation of larger clusters.
Article
Physics, Multidisciplinary
Tivadar Pongo, Viktoria Stiga, Janos Torok, Sara Levay, Balazs Szabo, Ralf Stannarius, Raul Cruz Hidalgo, Tamas Borzsonyi
Summary: This study investigated the discharge process of granular flow from a silo through experimental and numerical methods. It found that particle stiffness significantly affects the discharge characteristics, with differences in discharge behavior observed between deformable and hard grains at different friction coefficients. The study also analyzed the pressure fields during discharge and proposed a formulation to predict the flow rate decrease with decreasing filling height for soft particles with low friction coefficient.
NEW JOURNAL OF PHYSICS
(2021)
Article
Astronomy & Astrophysics
Birko-Katarina Ruzicka, Matthias Schroeter, Andreas Pack, Hermann Boehnhardt
Summary: The method utilizes properties of the frequency domain in images found by using the Fourier transform and effectively detects and analyzes lineament structures on the Hathor cliff of comet 67P, revealing important insights into the comet's formation and evolution.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Multidisciplinary Sciences
Dmitry Puzyrev, David Fischer, Kirsten Harth, Torsten Trittel, Raul Cruz Hidalgo, Eric Falcon, Martial Noirhomme, Eric Opsomer, Nicolas Vandewalle, Yves Garrabos, Carole Lecoutre, Fabien Palencia, Ralf Stannarius
Summary: Studying the dynamics of granular multiparticle ensembles requires optical analysis methods. Numerical simulations similar to experiments can be used to validate the reliability of analysis methods. This approach not only confirms the accuracy of simulations, but also tests the applicability of visual analysis.
SCIENTIFIC REPORTS
(2021)
Article
Crystallography
Amine Missaoui, Emmanuelle Lacaze, Alexey Eremin, Ralf Stannarius
Summary: This study experimentally confirmed the theoretical prediction using fluorescence labeling, showing that defects with different strengths in freely suspended films in the smectic C phase move at different speeds during annihilation.
Article
Astronomy & Astrophysics
Marius Pfeifer, Jessica Agarwal, Matthias Schroeter
Summary: This study used data from the European Space Agency's Rosetta mission to track the motion of particles in image sequences and derive their velocities and accelerations. An algorithm was developed to locate the particles and reconstruct their tracks using the image sequences' pair-nature. The study found significant information about potential genuine particle tracks and obtained preliminary results on velocity, acceleration, and radius distributions.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Materials Science, Multidisciplinary
Ralf Stannarius, Jonas Schulze
Summary: This study investigates the packing problem of crosses and examines the packing density achieved by random packing, as well as the local correlations of orientations and positions. The results suggest that there are typical local configurations that affect the orientational correlations.
Article
Instruments & Instrumentation
P. Born, M. Braibanti, L. Cristofolini, S. Cohen-Addad, D. J. Durian, S. U. Egelhaaf, M. A. Escobedo-Sanchez, R. Hoehler, T. D. Karapantsios, D. Langevin, L. Liggieri, M. Pasquet, E. Rio, A. Salonen, M. Schroeter, M. Sperl, R. Suetterlin, A. B. Zuccolotto-Bernez
Summary: An experiment container with light scattering and imaging diagnostics has been developed for studying soft matter aboard the ISS. It offers measurement capabilities to study different materials using exchangeable sample cell units. The experiment container has shown its capabilities in studying various materials based on initial results obtained on ground and during commissioning on the ISS.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2021)
Article
Crystallography
Torsten Trittel, Christoph Klopp, Kirsten Harth, Ralf Stannarius
Summary: Liquid-crystal columns were prepared and observed under microgravity conditions during suborbital rocket flights. The collapse of the columns was observed in the isotropic and nematic phases, but they survived in the smectic A and C mesophases due to the different yield stress of the material. The research provides important experimental data for understanding the behavior of liquid-crystal materials in microgravity.
Article
Materials Science, Multidisciplinary
Jing Wang, Zohreh Farmani, Joshua A. Dijksman, Cindy Luebeck, Oliver Speck, Ralf Stannarius
Summary: We introduce a new Magnetic Resonance Imaging technique to study the geometry of shear zones of soft, low-frictional and hard, frictional granular materials and their mixtures. Our findings show that the shear zone geometry differs considerably between soft grains submersed in water and the same material without the embedding fluid.
Article
Physics, Multidisciplinary
Jing Wang, Kirsten Harth, Dmitry Puzyrev, Ralf Stannarius
Summary: This study investigates the discharge behavior of soft particles in the presence of an obstacle, finding that the obstacle reduces the flow rates and increases the clogging probabilities, contrary to the effect observed in pedestrian dynamics.
NEW JOURNAL OF PHYSICS
(2022)
Article
Physics, Multidisciplinary
Tivadar Pongo, Bo Fan, Dariel Hernandez-Delfin, Janos Torok, Ralf Stannarius, Raul Cruz Hidalgo, Tamas Borzsonyi
Summary: This study investigates the time evolution of silo discharge for different granular materials, including spherical and elongated grains, using laboratory experiments and discrete element model (DEM) calculations. It is found that spherical grains exhibit a constant discharge rate, while elongated particles show a peculiar flow rate increase for larger orifices before the end of the discharge process. Furthermore, the flow field is practically homogeneous for spherical grains but has strong gradients for elongated particles, with a fast-flowing region in the middle of the silo surrounded by a stagnant zone.
NEW JOURNAL OF PHYSICS
(2022)
Article
Physics, Fluids & Plasmas
Mahdieh Mohammadi, Dmitry Puzyrev, Torsten Trittel, Ralf Stannarius
Summary: This study demonstrates that nonconvex grain shapes can lead to qualitatively novel macroscopic dynamics, different from convex grains. Hexapod grains at the surface migrate towards the rotation center and sink, mimicking a reverse Weissenberg effect. The observed surface flow field suggests a radial outward flow in the depth of the granular bed, forming a convection cell.
Article
Multidisciplinary Sciences
Alexey Eremin, Hajnalka Nadasi, Ralf Stannarius
Summary: Interactions between magnetic nanoparticles and an anisotropic environment lead to new magneto-optical, rheological, and mechanical phenomena, providing opportunities for developing novel multifunctional materials.
PHYSICAL SCIENCES REVIEWS
(2022)
Article
Chemistry, Physical
Amine Missaoui, Kirsten Harth, Torsten Trittel, Christoph Klopp, Ralf Stannarius, Emmanuelle Lacaze
Summary: This study reports the wrinkling and bulging phenomenon of thin freely floating films of smectic liquid crystals under rapid compression in-plane. Different patterns, including specifically shaped bulges, radial wrinkles, and target-like wrinkle structures, were observed depending on the external stress and dimensions of the films. These patterns disappear reversibly when the external stress is relaxed.
Article
Physics, Fluids & Plasmas
Sara Levay, David Fischer, Ralf Stannarius, Ellak Somfai, Tamas Borzsonyi, Lothar Brendel, Janos Torok
Summary: The study introduced a simple system to analyze the statistical properties of jammed granular ensembles and test Edwards' theory. Results showed that in a coupled system of two subsystems with different properties, the system must be considered as a single entity to be described by Edwards' theory, as constraints in stresses lead to counterintuitive effects.
