Quantitative analysis of flow dynamics of organic granular materials inside a versatile silo model during time-lapse X-ray tomography experiments

• Published in: Computers and electronics in agriculture Vol. 172; p. 105346
• Main Authors: Babout, Laurent, Grudzień, Krzysztof, Waktola, Selam, Miśkiewicz, Konrad, Adrien, Jerome, Maire, Eric
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-05-2020; Elsevier BV; Elsevier
• Subjects: 3D particle analysis; Asymmetric flows; Coordination numbers; Discharge; Elongation; Funnel flow; Granular materials; Image processing; Image quality; Material properties; Mechanical properties; Numerical prediction; Packing density; Parameter identification; Physics; Quantitative analysis; Silo construction; Sorghum; Tomography; X-ray tomography; X-ray tomography; Silo construction; Asymmetric flows; 3D particle analysis; Funnel flow
• ISSN: 0168-1699; 1872-7107
• DOI: 10.1016/j.compag.2020.105346

•A new X-ray CT compatible-like silo generation was designed to explore asymmetric flow dynamics.•Proposed image processing strategy allows to investigate at different scales bulk granular behavior.•Dense flow zone appears in eccentric funnel flow above larger hopper inclination.•Coordination number distributions match well with observed changes in packing density.•X-ray tomography results show more marked orientation changes for rice than sorghum.
Gravitational flows, like silo discharge, vary in mode and are complex to identify since they depend on various parameters, ranging from silo structural properties to granular material properties. Moreover, the way cohesionless particles arrange themselves during the flow is still a matter of study and new experimental approaches are needed. Here, the paper introduces a new versatile silo model that was specially designed for in situ X-ray tomography studies of silo discharge for various flow conditions, namely concentric and eccentric. The presented work focuses on organic granular materials, i.e. sorghum and rice, which present relatively similar physico-mechanical properties but different elongation. The high-quality tomography images combined with adequate image processing strategy allow to unambiguously analyse individual grains dynamic behaviour during silo discharge for different hopper configurations. The paper focuses on the analysis of packing density, coordination number and grain rotation changes during funnel flow. The quantitative analysis essentially shows that hopper eccentricity and particle elongation influence flow dynamics of funnel flow. The proposed experimental methodology is proven to be solid enough to investigate in more detail dynamic phenomena during silo discharge. It can also serve as a strong baseline for numerical calibration and predictions.