arXiv subjects

Michel Versluis

Publications and source records attributed to Michel Versluis.

41 records · Page 3Linked to original sources

arXiv2009

Collapse of Non-Axisymmetric Cavities

A round disk with a harmonic disturbance impacts on a water surface and creates a non-axisymmetric cavity which collapses under the influence of hydrostatic pressure. We use disks deformed with mode m=2 to m=6. For all mode numbers we find clear evidence for a phase inversion of the cavity wall during the collapse. We present a fluid dynamics video showing high speed imaging of different modes, pointing out the characteristic features during collapse.

physics.flu-dyn↗

arXiv2007

On the sound of snapping shrimp

Fluid dynamics video: Snapping shrimp produce a snapping sound by an extremely rapid closure of their snapper claw. Our high speed imaging of the claw closure has revealed that the sound is generated by the collapse of a cavitation bubble formed in a fast flowing water jet forced out from the claws during claw closure. The produced sound originates from the cavitation collapse of the bubble. At collapse a short flash of light is emitted, just as in single bubble sonoluminescence. A model based on the Rayleigh-Plesset equation can quantitatively account for the visual and acoustical observations.

physics.flu-dyn↗

arXiv2006

Leaping shampoo and the stable Kaye effect

Shear-thinning fluids exhibit surprisingly rich behaviour. One example is the Kaye effect which occurs when a thin stream of a solution of polyisobutylene in Decalin is poured into a dish of the fluid. As pouring proceeds, a small stream of liquid occasionally leaps upward from the heap. This surprising effect, which lasts only a second or so, is named after its first observer A. Kaye, who could offer no explanation for this behaviour. Later, Collyer and Fischer suggested from 250 frames per second cine recordings that the fluid must be highly shear thinning as well as elastic and 'pituitous'. In addition, they concluded that a rigid surface is required to back the reflected liquid stream. While the words bouncing and reflection are associated with non-continuous and elastic effects, we will show here that the Kaye effect is in fact a continuous flow phenomenon. We show that the Kaye effect works for many common fluids, including shampoos and liquid soaps. We reveal its physical mechanism (formation, stability and disruption) through high-speed imaging. The measurements are interpreted with a simple theoretical model including only the shear thinning behaviour of the liquid; elastic properties of the liquid play no role. We show that the Kaye effect can be stable and that it can be directed. We even demonstrate a stable Kaye effect on a thin soap film excluding the necessity of a rigid backing surface.

physics.flu-dyn↗

arXiv2004

Impact

According to Shoemaker, the "impact of solid bodies is the most fundamental process that has taken place on the terrestrial planets", as they shape the surfaces of all solar system bodies. A lot of information on this process has been extracted from remote observations of impact craters on planetary surfaces. However, the nature of the geophysical impact events is that they are non-reproducible. Moreover, their scale is enormous and direct observations are not possible. Therefore, we choose an alternate and of course downscaled experimental approach in order to guarantee reproducible results: We prepare very fine sand in a well defined and fully decompactified state by letting gas bubble through it. After turning off the gas stream, we let a steel ball fall on the sand. The series of events in the experiments and corresponding discrete particle simulations is as follows: On impact of the ball, sand is blown away in all directions ("splash") and an impact crater forms. When this cavity collapses, a granular jet emerges and is driven straight into the air. A second jet goes downwards into the air bubble entrained during the process, thus pushing surface material deep into the ground. The air bubble rises slowly towards the surface, causing a granular eruption. In addition to the experiments and the discrete particle simulations we present a simple continuum theory to account for the void collapse leading to the formation of the upward and downward jets. We show that the phenomenon is robust and even works for oblique impacts: the upward jet is then shooting backwards, in the direction where the projectile came from.

cond-mat.other↗

arXiv2001

Hysteretic clustering in granular gas

Granular material is vibro-fluidized in N=2 and N=3 connected compartments, respectively. For sufficiently strong shaking the granular gas is equi-partitioned, but if the shaking intensity is lowered, the gas clusters in one compartment. The phase transition towards the clustered state is of 2nd order for N=2 and of 1st order for N=3. In particular, the latter is hysteretic. The experimental findings are accounted for within a dynamical model that exactly has the above properties.

nlin.CD↗