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The contact dynamics (CD) method is an efficient simulation technique of dense granular media where unilateral and frictional contact problems for a large number of rigid bodies have to be solved. In this paper, we present a modified version of the CD to generate homogeneous random packings of rigid grains. CD simulations are performed at constant external pressure, which allows the variation of the size of a periodically repeated cell. We follow the concept of the Andersen dynamics and show how it can be applied within the framework of the CD method. The main challenge here is to handle the interparticle interactions properly, which are based on constraint forces in CD. We implement the proposed algorithm, perform test simulations, and investigate the properties of the final packings.

We present a numerical method to deal efficiently with large numbers of particles in incompressible fluids. The interactions between particles and fluid are taken into account by a physically motivated ansatz based on locally defined drag forces. We demonstrate the validity of our approach by performing numerical simulations of sedimenting non-Brownian spheres in two spatial dimensions and compare our results with experiments. Our method reproduces qualitatively important aspects of the experimental findings, in particular the strong anisotropy of the hydrodynamic bulk self-diffusivities.

We study experimentally the transport of heap formed by granular materials vertically vibrated on an inclined surface. A relationship is presented of how the velocity of heap changing with driving acceleration and frequency. The shape of the heap bottom is measured by detecting the colliding phase of the heap bottom with plane. An analogous experiment is performed with a heap shape block of Plexiglas. The mechanism for transport of the heap is presented.

The Great Hanshin-Awaji Earthquake of 1995 has left traces of its intense seismic motion in granular soils at various places in Kobe, and these signs are found to be somehow correlated with the features of the disaster at those places. Strong ground shaking was responsible for a number of slope failures. Considerable displacements seem to have been built up even within nearly flat sandy soil deposits, a fact proven by the data regarding dislocated rings of manholes. Thus the importance of studying behaviours of granular soil experiencing this large strain emerges from the findings obtained through the investigation. Irreversible deformation of a granular material is mainly due to a change in its fabric. This process is accompanied by noticeable dilation, through which a certain amount of energy is consumed. It is therefore noted that ground velocity as well as acceleration is another important key which provides a stability index. On the basis of findings through experiments using a new visualisation technique, Laser-Aided Tomography (LAT), a simple approach for evaluating granular soil deformation built up during intense ground shaking is discussed.