The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
J. C. Ruiz-suárez - One of the best experts on this subject based on the ideXlab platform.
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Infinite Penetration of a Projectile into a Granular Medium
Physical review letters, 2011Co-Authors: F. Pacheco-vázquez, Gabriel A. Caballero-robledo, J. M. Solano-altamirano, Ernesto Altshuler, A. J. Batista-leyva, J. C. Ruiz-suárezAbstract:An object falling in a fluid reaches a terminal velocity when the drag force and its weight are balanced. Contrastingly, an object impacting into a Granular Medium rapidly dissipates all its energy and comes to rest always at a shallow depth. Here we study, experimentally and theoretically, the penetration dynamics of a projectile in a very long silo filled with expanded polystyrene particles. We discovered that, above a critical mass, the projectile reaches a terminal velocity and, therefore, an endless penetration.
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Cooperative dynamics in the penetration of a group of intruders in a Granular Medium
Nature Communications, 2010Co-Authors: F. Pacheco-vázquez, J. C. Ruiz-suárezAbstract:Objects moving through fluids and Granular media experience drag forces that determine their dynamics. The authors consider the case of multiple objects moving through a low-density Granular material and show that their dynamics are cooperative. An object moving in a fluid experiences a drag force that depends on its velocity, shape and the properties of the Medium. From this simplest case to the motion of a flock of birds or a school of fish, the drag forces and the hydrodynamic interactions determine the full dynamics of the system. Similar drag forces appear when a single projectile impacts and moves through a Granular Medium, and this case is well studied in the literature. On the other hand, the case in which a group of intruders impact a Granular material has never been considered. Here, we study the simultaneous penetration of several intruders in a very low-density Granular Medium. We find that the intruders move through it in a collective way, following a cooperative dynamics, whose complexity resembles flocking phenomena in living systems or the movement of reptiles in sand, wherein changes in drag are exploited to efficiently move or propel.
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Sliding through a superlight Granular Medium.
Physical Review E, 2009Co-Authors: F. Pacheco-vázquez, J. C. Ruiz-suárezAbstract:We explore the penetration dynamics of an intruder in a Granular Medium composed of expanded polystyrene spherical particles. Three features distinguish our experiment from others studied so far in Granular physics: (a) the impact is horizontal, decoupling the effects of gravity and the drag force; (b) the density of the intruder ${\ensuremath{\rho}}_{i}$ is up to 350 times larger than the density of the Granular Medium ${\ensuremath{\rho}}_{m}$; and (c) the way the intruder moves through the material, sliding at the bottom of the column with small friction. Under these conditions we find that the final penetration $D$ scales with $({\ensuremath{\rho}}_{i}/{\ensuremath{\rho}}_{m})$ and the drag force ${F}_{d}$ and $D$ saturate with the height of the Granular bed.
Pierre Jop - One of the best experts on this subject based on the ideXlab platform.
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Erosion dynamics of a wet Granular Medium
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics, 2013Co-Authors: G Lefebvre, Pierre JopAbstract:Liquid may give strong cohesion properties to a Granular Medium, and confer a solidlike behavior. We study the erosion of a fixed circular aggregate of wet Granular matter subjected to a flow of dry grains inside a half-filled rotating drum. During the rotation, the dry grains flow around the fixed obstacle. We show that its diameter decreases linearly with time for low liquid content, as wet grains are pulled out of the aggregate. This erosion phenomenon is governed by the properties of the liquids. The erosion rate decreases exponentially with the surface tension while it depends on the viscosity to the power -1. We propose a model based on the force fluctuations arising inside the flow, explaining both dependencies: The capillary force acts as a threshold and the viscosity controls the erosion time scale. We also provide experiments using different flowing grains, confirming our model.
F. Pacheco-vázquez - One of the best experts on this subject based on the ideXlab platform.
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Infinite Penetration of a Projectile into a Granular Medium
Physical review letters, 2011Co-Authors: F. Pacheco-vázquez, Gabriel A. Caballero-robledo, J. M. Solano-altamirano, Ernesto Altshuler, A. J. Batista-leyva, J. C. Ruiz-suárezAbstract:An object falling in a fluid reaches a terminal velocity when the drag force and its weight are balanced. Contrastingly, an object impacting into a Granular Medium rapidly dissipates all its energy and comes to rest always at a shallow depth. Here we study, experimentally and theoretically, the penetration dynamics of a projectile in a very long silo filled with expanded polystyrene particles. We discovered that, above a critical mass, the projectile reaches a terminal velocity and, therefore, an endless penetration.
-
Cooperative dynamics in the penetration of a group of intruders in a Granular Medium
Nature Communications, 2010Co-Authors: F. Pacheco-vázquez, J. C. Ruiz-suárezAbstract:Objects moving through fluids and Granular media experience drag forces that determine their dynamics. The authors consider the case of multiple objects moving through a low-density Granular material and show that their dynamics are cooperative. An object moving in a fluid experiences a drag force that depends on its velocity, shape and the properties of the Medium. From this simplest case to the motion of a flock of birds or a school of fish, the drag forces and the hydrodynamic interactions determine the full dynamics of the system. Similar drag forces appear when a single projectile impacts and moves through a Granular Medium, and this case is well studied in the literature. On the other hand, the case in which a group of intruders impact a Granular material has never been considered. Here, we study the simultaneous penetration of several intruders in a very low-density Granular Medium. We find that the intruders move through it in a collective way, following a cooperative dynamics, whose complexity resembles flocking phenomena in living systems or the movement of reptiles in sand, wherein changes in drag are exploited to efficiently move or propel.
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Sliding through a superlight Granular Medium.
Physical Review E, 2009Co-Authors: F. Pacheco-vázquez, J. C. Ruiz-suárezAbstract:We explore the penetration dynamics of an intruder in a Granular Medium composed of expanded polystyrene spherical particles. Three features distinguish our experiment from others studied so far in Granular physics: (a) the impact is horizontal, decoupling the effects of gravity and the drag force; (b) the density of the intruder ${\ensuremath{\rho}}_{i}$ is up to 350 times larger than the density of the Granular Medium ${\ensuremath{\rho}}_{m}$; and (c) the way the intruder moves through the material, sliding at the bottom of the column with small friction. Under these conditions we find that the final penetration $D$ scales with $({\ensuremath{\rho}}_{i}/{\ensuremath{\rho}}_{m})$ and the drag force ${F}_{d}$ and $D$ saturate with the height of the Granular bed.
G Lefebvre - One of the best experts on this subject based on the ideXlab platform.
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Erosion dynamics of a wet Granular Medium
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics, 2013Co-Authors: G Lefebvre, Pierre JopAbstract:Liquid may give strong cohesion properties to a Granular Medium, and confer a solidlike behavior. We study the erosion of a fixed circular aggregate of wet Granular matter subjected to a flow of dry grains inside a half-filled rotating drum. During the rotation, the dry grains flow around the fixed obstacle. We show that its diameter decreases linearly with time for low liquid content, as wet grains are pulled out of the aggregate. This erosion phenomenon is governed by the properties of the liquids. The erosion rate decreases exponentially with the surface tension while it depends on the viscosity to the power -1. We propose a model based on the force fluctuations arising inside the flow, explaining both dependencies: The capillary force acts as a threshold and the viscosity controls the erosion time scale. We also provide experiments using different flowing grains, confirming our model.
J C Ruizsuarez - One of the best experts on this subject based on the ideXlab platform.
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sliding through a superlight Granular Medium
Physical Review E, 2009Co-Authors: F Pachecovazquez, J C RuizsuarezAbstract:: We explore the penetration dynamics of an intruder in a Granular Medium composed of expanded polystyrene spherical particles. Three features distinguish our experiment from others studied so far in Granular physics: (a) the impact is horizontal, decoupling the effects of gravity and the drag force; (b) the density of the intruder rho(i) is up to 350 times larger than the density of the Granular Medium rho(m); and (c) the way the intruder moves through the material, sliding at the bottom of the column with small friction. Under these conditions we find that the final penetration D scales with (rho(i)/rho(m)) and the drag force Fd and D saturate with the height of the Granular bed.
