INSTITUTO DE FISICA DE LIQUIDOS Y SISTEMAS BIOLOGICOS
Unidad Ejecutora - UE
congresos y reuniones científicas
"Faster is slower" effect in granular flows
P. A. GAGO; D. R. PARISI; L. A. PUGNALONI; J. P. PERALTA ; R. M. IRASTORZA
Workshop; Southern Workshop on Granular Materials; 2012
Universidad de Chile, Universidad de Santiago y Universidad del Bío-Bío Chile.
A key problem in evacuation dynamics is the escape of highly competitive pedestrians through a narrow door. A so called faster is slower (FIS) effect has been predicted according to which there exists an optimum pedestrian desired velocity that yields the shortest mean evacuation time. This is related with the appearance of blocking clusters that intermittently clog the exit door. In the case of granular flow, we can make an analogy with pedestrian flow based on the contact forces. It was shown that the contact forces play a key role in the FIS effect found in simulations. The social forces are not relevant here since pedestrians behave under panic conditions. We have carried out an experiment that consists of a quasi two-dimensional silo and hopper placed on a vibrating inclined plane. Increasing the angle of the plane leads to an increase in the component of the force of gravity parallel to the incline. This is similar to increasing the driving force for model pedestrians. Since blocking arches are much more stable in granular flows than in self-propelled particle flows, we add an external perturbation by applying an external vibration which is an aid to the rearrangement of grains that promote breaking of blockages. In this work we show that the experimental system do exhibit the FIS effect.