Giant bubble pinch-off

Self-similarity has been the paradigmatic picture for the pinch-off of a drop. Here we will show through high-speed imaging and boundary integral simulations that the inverse problem, the pinch-off of an air bubble in water, is not self-similar in a strict sense: A disk is quickly pulled through a water surface, leading to a giant, cylindrical void which after collapse creates an upward and a downward jet. Only in the limiting case of large Froude number the neck radius $h$ scales as $h(-\log h)^{1/4} \propto \tau^{1/2}$, the purely inertial scaling. For any finite Froude number the collapse is slower, and a second length-scale, the curvature of the void, comes into play. Both length-scales are found to exhibit power-law scaling in time, but with different exponents depending on the Froude number, signaling the non-universality of the bubble pinch-off.Comment: 5 pages, 2 figures. Figure quality was reduced considerably and converted to greyscale to decrease file siz

Towards device-size atomistic models of amorphous silicon

The atomic structure of amorphous materials is believed to be well described by the continuous random network model. We present an algorithm for the generation of large, high-quality continuous random networks. The algorithm is a variation of the "sillium" approach introduced by Wooten, Winer, and Weaire. By employing local relaxation techniques, local atomic rearrangements can be tried that scale almost independently of system size. This scaling property of the algorithm paves the way for the generation of realistic device-size atomic networks.Comment: 7 pages, 3 figure

The Early Royal Society and Visual Culture

Recent studies have fruitfully examined the intersection between early modern science and visual culture by elucidating the functions of images in shaping and disseminating scientific knowledge. Given its rich archival sources, it is possible to extend this line of research in the case of the Royal Society to an examination of attitudes towards images as artefacts –manufactured objects worth commissioning, collecting and studying. Drawing on existing scholarship and material from the Royal Society Archives, I discuss Fellows’ interests in prints, drawings, varnishes, colorants, images made out of unusual materials, and methods of identifying the painter from a painting. Knowledge of production processes of images was important to members of the Royal Society, not only as connoisseurs and collectors, but also as those interested in a Baconian mastery of material processes, including a “history of trades”. Their antiquarian interests led to discussion of painters’ styles, and they gradually developed a visual memorial to an institution through portraits and other visual records.AH/M001938/1 (AHRC

Shape-induced capilary interactions of colloidal particles

We show that near-spherical micrometer-sized colloidal particles at an interface of two fluids experience inter-particle forces merely as a consequence of their shape-induced capillary interaction. The interaction is strong even if the deviations from sphericity are on the nm-scale, and can hardly be avoided in experiment. For particles of 2 μm radius, a deformation of 20 nm can result in an attractive potential of 2kBT at a distance of 4 particle radii. Dynamical simulations of many particles confirm that the forces lead to aggregates of dendritic or hexagonal-lattice type. The latter pattern exhibits strong herringbone-phase orientational order

Shape-induced capillary interactions of colloidal particles

We show that near-spherical micrometer-sized colloidal particles at an interface of two fluids experience inter-particle forces merely as a consequence of their shape-induced capillary interaction. The interaction is strong even if the deviations from sphericity are on the nm-scale, and can hardly be avoided in experiment. For particles of 2 μm radius, a deformation of 20 nm can result in an attractive potential of 2kBT at a distance of 4 particle radii. Dynamical simulations of many particles confirm that the forces lead to aggregates of dendritic or hexagonal-lattice type. The latter pattern exhibits strong herringbone-phase orientational order

Archeologisch onderzoek Diedensche Uiterdijk, deelproject Oeverzone, te Megen en Dieden : bureauonderzoek

Lit.opg. en begrippenlijst