We show that, when a mixture of small and large grains is simply poured in a g̀ranular Hele± Shaw cell’ (two transparent slabs separated by a gap of about 5mm), the grains spontaneously stratify in alternating layers of small and large grains parallel to the surface of the pile. The spontaneous self-strati® cation occurs only when the large grains have a larger angle of repose than the small gra...

We observe the formation of heaps of repulsive microspheres, created by flowing a colloidal microsphere suspension towards a flat-topped ridge placed within a quasi two-dimensional microfluidic channel. This configuration allows for both shear and normal forces on the microspheres in contact with the ridge. The heaps, which are formed against the ridge, are characterized by two distinct phases:...

Particle size and shape influence the production of solid dosage forms. This study aimed to use the three shape descriptors available in the literature to describe the shapes of six compounds, and evaluate whether angle of repose might predict the flowability of a powder sample the same as those made by compressibility index and Hausner ratio. Images of cephalexin monohydrate, niacin, nystatin,...

– We investigate the effects of lateral walls on the angle of movement and on the angle of repose of a granular pile. Our experimental results for beads immersed in water are similar to previous results obtained in air and to recent numerical simulations. All of these results, showing an increase of pile angles with a decreasing gap width, are explained by a model based on the redirection of st...