Super water-repellent surfaces occur naturally on plants and aquatic insects and are created in the laboratory by combining micro or nano-scale surface topographic features with hydrophobic surface chemistry. When such types of water-repellent surfaces are submerged they can retain a film of air (a plastron). In this work, we report measurements of the terminal velocity of solid acrylic spheres...

A dilute suspension of uniform, non-Brownian spheres settles slowly in a viscous solvent. The initially well-mixed system showing Poisson or random occupancy statistics evolves to a system having reduced number fluctuations, but otherwise appearing random. The reduced number fluctuations are consistent with recent measurements of velocity fluctuations in settling suspensions. These experimental...

We use a combination of original light scattering techniques and particles with unique optical properties to investigate the behavior of suspensions of attractive colloids under gravitational stress, following over time the concentration profile, the velocity profile, and the microscopic dynamics. During the compression regime, the sedimentation velocity grows nearly linearly with height, imply...

The focus of this paper is on the development of an input shaper/time-delay filter that permits the precise tracking of a ramp input, while eliminating residual vibrations. Zero phase error velocity tracking is often required in applications where moving parts have to be mated, such as manufacturing lines with high production output. A closed form solution to a pre-filtering technique is presen...

Dispersed multiphase flows occur in many biological, engineering and geophysical applications such as fluidized beds, soot particle dispersion and pyroclastic flows. Understanding the behavior of suspensions is a very difficult task. Indeed particles may differ in size, shape, density and stiffness, their concentration varies from one case to another, and the carrier fluid may be quiescent or t...

This article takes insights from a previously derived mathematical framework for the free settling velocity of particles any shape to model analytical constructs solve hindered hard shape. Because geometry physical environment and continuity can be strictly enforced in construct model, relative fluid front pumped upward by found, thus allowing calculation subtracting calculated velocity.

The interplay between the resultant of the hydrodynamic forces on a falling particle and of its weight represents the physical mechanism of sediment motion in streams. Transport of sediment occurs because of interaction of fluids with loose material of confined boundaries, which create a very complex set of conditions. The loose boundaries deform due to erosion and deposition. Moreover, the cas...

1. In open loop, the velocity response depends on the mechanical time constant of the DC machine (time response) and the value of the power supply. Indeed, for each value of power supply, a velocity value is reached in steady state. Therefore the DC machine can reach any value of velocity which depends only of the power supply. In this case no possibility to improve performances. 2. For a speci...