相关论文: Rise or sink: spherical intruder in density freque…

The intruder segregation dependence on size and density is investigated in the framework of a hydrodynamic theoretical model for vibrated granular media. We propose a segregation mechanism based on the difference of densities between…

Large objects, immersed in a homogeneous granular system, migrate when subjected to vibrations. Under certain conditions large heavy objects rise and similar light ones sink to the bottom. This is called reverse buoyancy. We report an…

Using MRI and high-speed video we investigate the motion of a large intruder particle inside a vertically shaken bed of smaller particles. We find a pronounced, non-monotonic density dependence, with both light and heavy intruders moving…

The segregation of large spheres in a granular bed under vertical vibrations is studied. In our experiments we systematically measure rise times as a function of density, diameter and depth; for two different sinusoidal excitations. The…

We study experimentally the dynamics of a dense intruder sinking under gravity inside a vibrated 2D granular packing. The surrounding flow patterns are characterized and the falling trajectories are interpreted in terms of an effectivive…

We computationally determine the force on single spherical intruder particles in sheared granular flows as a function of particle size, particle density, shear rate, overburden pressure, and gravitational acceleration. The force scales…

We investigate the effect of shape and orientation for a horizontally oscillating intruder on its vertical dynamics in a granular medium via Discrete Element Method (DEM) simulations. Five distinct intruder shapes were considered in this…

We study the behavior of cylindrical objects as they sink into a drygranular bed fluidized due to lateral oscillations. Somewhat unexpectedly, we have found that, within a large range of lateral shaking powers,cylinders with flat bottoms…

Sand is a highly dissipative system, where the local spatial arrangements and densities depend strongly on the applied forces, resulting in fluid-like or solid-like behaviour. This makes sand swimming challenging and intriguing, raising…

Using high-speed video and magnetic resonance imaging (MRI) we study the motion of a large sphere in a vertically vibrated bed of smaller grains. As previously reported we find a non-monotonic density dependence of the rise and sink time of…

We study the behavior of cylindrical objects as they sink into a dry granular bed fluidized due to lateral oscillations, in order to shed light on human constructions and other objects. Somewhat unexpectedly, we have found that, within a…

It has been recently reported that irregular objects sink irregularly when released in a granular medium: a subtle lack of symmetry in the density or shape of a macroscopic object may produce a large tilting and deviation from the vertical…

Recently, the existence of so-called granular bubbles and droplets has been demonstrated experimentally. Granular bubbles and droplets are clusters of particles that respectively rise and sink if submerged in an aerated and vibrated bed of…

The rise dynamics of a large spherical particle, in a granular bed under vertical vibrations, is experimentally studied. An inductive device has been designed to track the particle while it climbs through the bed under different conditions.…

The behaviour of a vertically vibrated granular bed is reminiscent of a liquid in that it exhibits many phenomena such as convection and Faraday-like surface waves. However, when the lateral dimensions of the bed are confined such that a…

This fluid dynamics video was submitted to the Gallery of Fluid Motion for the 2009 APS Division of Fluid Dynamics Meeting in Minneapolis, Minnesota. In this video we show some results from a simple experiment where air was injected by a…

We present experimental results for spherical particles rising and settling in a still fluid. Imposing a well-controlled center of mass offset enables us to vary the rotational dynamics selectively by introducing an intrinsic rotational…

We use a DEM simulation and analytical considerations to study the dynamics of a self-energised object, modelled as a disc, oscillating horizontally within a two-dimesional bed of denser and smaller particles. We find that, for given…

We investigate the effective friction encountered by an intruder moving through a sedimented medium which consists of transparent granular hydrogels immersed in water, and the resulting motion of the medium. We show that the effective…

We study the dynamics of an intruder moving through a fluidized granular medium in three dimensions ($d=3$). The intruder and grains have both translational and rotational degrees of freedom. The energy-dissipation mechanism is solid…