Clogging of granular materials in a horizontal hopper: Effect of outlet size, hopper angle, and driving velocity

Numerical study of granular flow in a slit funnel with a novel structure to avoid particle clogging

To solve the problem of particle clogging in slit funnels and to obtain a stable discharge flow rate, we proposed a new funnel structure, namely the slit baffle funnel. We conducted a systematic investigation using the discrete element method (DEM) to study the effects of funnel half-angle θ, outlet width W, and baffle height H on flow rate and flow pattern. We found that the proposed structure could effectively avoid particle clogging and guarantee a continuous and stable flow rate with small outlet width. Under the condition of H >3 d, a bigger flow rate was obtained at a smaller funnel half-angle. This new funnel structure could be applied to solve clogging problems associated with granular matter in the slit geometry in mining, agriculture, food, and pharmaceuticals.

Mixing particle softness in a two-dimensional hopper: Particle rigidity and friction enable variable arch geometry to cause clogging

Understanding the clogging of mixtures of soft and rigid particles flowing through hoppers becomes important as soft particle usage increases in consumer products. We investigate this clogging under varying particle size and rigid fraction by quantifying various properties of arches formed in the neck of a quasi-two-dimensional hopper. As more soft particles are added to the mixture, the arch tends to become both narrower and more curved. This effect arises from the fact that soft particles have less ability to sustain a clog than rigid particles. The clogging probability is seen to have a linear correlation with the span (width) of the arch. The angles between the arch particles are shown to have higher values as rigid fraction increases. The arch occasionally shows a partially convex shape at high rigid fractions when rigid particles are sitting next to each other, while soft particles can form angles of less than 180^{∘} only. The relation between the span and aspect ratio (width to height) of the arch is theoretically formulated for three-particle arches and extended to arches of more than three particles, using an asymptotic parameter that represents the width of a flat arch. Finally, it is concluded that clogging probability closely correlates with both the arch span and the variation of other geometric arch properties.