arXiv subjects

H. A. Knudsen

Publications and source records attributed to H. A. Knudsen.

2 recordsLinked to original sources

arXiv2009

Snell's Law for Shear Zone Refraction in Granular Materials

We present experiments on slow shear flow in a split-bottom linear shear cell, filled with layered granular materials. Shearing through two different materials separated by a flat material boundary is shown to give narrow shear zones, which refract at the material boundary in accordance with Snell's law in optics. The shear zone is the one that minimizes the dissipation rate upon shearing, i.e.a manifestation of the principle of least dissipation. We have prepared the materials as to form a granular lens. Shearing through the lens is shown to give a very broad shear zone, which corresponds to fulfilling Snell's law for a continuous range of paths through the cell.

cond-mat.soft↗

arXiv2005

Aggregation in Charged Nano Suspensions

In order to control aggregation phenomena in suspensions of nanoparticles, one often charges the particles electrically, e.g. by triboelectric charging. Stabilization of suspensions against aggregation of particles is an important issue, which may be realized by monopolar charging, where particles repel each other. Contrarily, bipolar charging may be used in coating processes, where smaller particles of one material coat larger particles of another material. When the two particle fractions are charged oppositely, aggregation between equally charged particles is hindered whereas aggregation between oppositely charged particles is preferred, thereby improving the coating process. We study various aspects of these two situations by theoretical investigations and computer simulations.

physics.gen-ph↗