Periodic Reporting for period 2 - CALIPER (Creating Granular Materials Experts by Developing Experimental Calibrations for Computational Methods)
Reporting period: 2021-09-01 to 2024-02-29
Granular materials such as sand, salt grains and coffee beans are everywhere. Predicting how granular materials flow and deform is obviously important for a wide range of sectors, yet still a highly challenging task. Computational methods to assist in handling granular materials have greatly improved in the past decades. However, these computational methods need more and more experimental calibration. Current calibration technology is completely insufficient to provide the required information to calibrate computational methods.
CALIPER has trained a cohort of experimental and computational experts by letting them develop and use innovative granular calibration technologies for industrial and academic purposes. The calibration methodologies are based primarily on three dimensional imaging methods and advanced mechanical characterization techniques, of which we have explored many. CALIPER has so provided Europe with new knowledge and a unique team of professionals that will enhance the academic and industrial innovation capacity in a wide range of sectors for years to come.
CALIPER has trained a cohort of experimental and computational experts by letting them develop and use innovative granular calibration technologies for industrial and academic purposes. The calibration methodologies are based primarily on three dimensional imaging methods and advanced mechanical characterization techniques, of which we have explored many. CALIPER has so provided Europe with new knowledge and a unique team of professionals that will enhance the academic and industrial innovation capacity in a wide range of sectors for years to come.
CALIPER has resulted in 10+ PhD theses, 30+ scientic peer reviewed publications, dozens of conference posters and presentations, over 30 outreach events for the general public, an Instagram channel @caliper_itn and website (www.caliper-itn.org). The total reach of these efforts can be estimates by conference session attendences and site visits and easily reaches into the hundreds of specialists and thousands of members of the general public reached.
CALIPER has resulted in the creation of an online MOOC to train newcomers in numerical methods at https://imoox.at/course/dem(opens in new window). This MOOC has been further supported by the eScienceCenter from Amsterdam, and in its initial run already reached hundreds of participants. The course will remain hosted by TU Graz and available into the foreseeable future.
We have defined a custom set of particle shapes called "Caliparticles" that granular materials researchers can use to calibrate flow measurements on granular materials, both experimentally and numerically. The shapes are published in an open source community page on Zenodo (https://zenodo.org/communities/caliper/(opens in new window)). The data from the public repository has already been downloaded hundreds of times.
CALIPER has trained its students in four online and in-person training schools, and has organized a further four regional meetings to facilitate networking. Several trainers have fostered team work, provided CV, resume and LinkedIn training for the students working in CALIPER. Much of the training materials covered in these training sessions has made it into the MOOC.
CALIPER also co-financed an international workshop at the Lorentz Center in Leiden, where many of the CALIPER participants could attend and present and discuss their results. Besides a significant CALIPER attendance, 30+ international scientific experts convended for one week to use Open Space Technology discussion techniques and online sketchbooks to connect the results from CALIPER and many other research efforts across a range of disciplines. CALIPER is even able to contribute to a well known conference in the field, the Granular Matter session of the Gordon Research Seminar.
CALIPER has resulted in the creation of an online MOOC to train newcomers in numerical methods at https://imoox.at/course/dem(opens in new window). This MOOC has been further supported by the eScienceCenter from Amsterdam, and in its initial run already reached hundreds of participants. The course will remain hosted by TU Graz and available into the foreseeable future.
We have defined a custom set of particle shapes called "Caliparticles" that granular materials researchers can use to calibrate flow measurements on granular materials, both experimentally and numerically. The shapes are published in an open source community page on Zenodo (https://zenodo.org/communities/caliper/(opens in new window)). The data from the public repository has already been downloaded hundreds of times.
CALIPER has trained its students in four online and in-person training schools, and has organized a further four regional meetings to facilitate networking. Several trainers have fostered team work, provided CV, resume and LinkedIn training for the students working in CALIPER. Much of the training materials covered in these training sessions has made it into the MOOC.
CALIPER also co-financed an international workshop at the Lorentz Center in Leiden, where many of the CALIPER participants could attend and present and discuss their results. Besides a significant CALIPER attendance, 30+ international scientific experts convended for one week to use Open Space Technology discussion techniques and online sketchbooks to connect the results from CALIPER and many other research efforts across a range of disciplines. CALIPER is even able to contribute to a well known conference in the field, the Granular Matter session of the Gordon Research Seminar.
Our three scientific Work Packages considered deformable, irregular and cohesive granular materials, and for each of these types of grains we have developed new scientific perspectives, sometimes combining the work from different work packages. We have advanced calibration methods for granular materials to better characterize these materials both on their mechanical behavior and their microstructural evolution. We have advanced several numerical methods to better simulate soft particles flows, and particle flows of anisometric grains. We have been able to image the swelling of soft, deformable, anisometric couscous particles in 3D with both X-ray tomography and neutron tomography, providing the highest detail so far of a granular process that involves soft, sticky particles. These results have even been combined with NMR confirmation of hydration levels, which is an industry first.
We have extensively studied deformable, irregular and cohesive granular flows in silos and hoppers, revealing new important couplings between the frictional and elastic behavior of granular materials, the role of deformability and shape in classic equations such as the Hagen-Beverloo equation. We have additionally characterized frictional and adhesive contacts in deformable and irregular flows and have cross-calibrated numerical particle models on experimental results for different flow geometries, including more classic floe geometries such as a Schulze ring-shear tester. We have developed novel discrete element method code to simulate the continuous and oscillatory flow behavior of deformable particles, the interactions among them and their coarse-grained mechanical response.
Scientifically, the network has studied a very broad array of granular samples, ranging from ceramic particles used in ceramic tile production, to rice grains, macaroni particles, mustard seeds, couscous grains and hydrogel beads and an array of model shapes including non-convex tripods and hexapods. We have developed custom flow geometries for slow flow imaging in special rheometric configurations, allowing for full characterization of flow behavior. The flow geometries are suitable for slow and fast flow imaging. In general, we have used an extremely wide range of flow imaging modalities: slow and high speed X-ray, MRI, high speed imaging and neutron tomography. We have also combined some of these imaging modalities. We have used and developed various numerical methods to study granular materials, including hybrid GPU-CPU frameworks. An extensive calibration workflow scheme is also developed that works together with industry-standard discrete element method simulation codes.
Summarizing, the scientific work has resulted in many new perspectives on hopper flow physics as relevant for industrial practice, new three dimensional flow rules for slow flows of non-convex particles shapes, a new understanding of the cohesive nature of ceramic particles, the establishment of new microscopic pictures behind the role of rotations of grains in geophysical context, new modeling perspectives for the elastic behavior of soft particle packings among others.
We have extensively studied deformable, irregular and cohesive granular flows in silos and hoppers, revealing new important couplings between the frictional and elastic behavior of granular materials, the role of deformability and shape in classic equations such as the Hagen-Beverloo equation. We have additionally characterized frictional and adhesive contacts in deformable and irregular flows and have cross-calibrated numerical particle models on experimental results for different flow geometries, including more classic floe geometries such as a Schulze ring-shear tester. We have developed novel discrete element method code to simulate the continuous and oscillatory flow behavior of deformable particles, the interactions among them and their coarse-grained mechanical response.
Scientifically, the network has studied a very broad array of granular samples, ranging from ceramic particles used in ceramic tile production, to rice grains, macaroni particles, mustard seeds, couscous grains and hydrogel beads and an array of model shapes including non-convex tripods and hexapods. We have developed custom flow geometries for slow flow imaging in special rheometric configurations, allowing for full characterization of flow behavior. The flow geometries are suitable for slow and fast flow imaging. In general, we have used an extremely wide range of flow imaging modalities: slow and high speed X-ray, MRI, high speed imaging and neutron tomography. We have also combined some of these imaging modalities. We have used and developed various numerical methods to study granular materials, including hybrid GPU-CPU frameworks. An extensive calibration workflow scheme is also developed that works together with industry-standard discrete element method simulation codes.
Summarizing, the scientific work has resulted in many new perspectives on hopper flow physics as relevant for industrial practice, new three dimensional flow rules for slow flows of non-convex particles shapes, a new understanding of the cohesive nature of ceramic particles, the establishment of new microscopic pictures behind the role of rotations of grains in geophysical context, new modeling perspectives for the elastic behavior of soft particle packings among others.